1. Introduction
1.1. Background
This section is non-normative.
HTML is the World Wide Web’s core markup language. Originally, HTML was primarily designed as a language for semantically describing scientific documents. Its general design, however, has enabled it to be adapted, over the subsequent years, to describe a number of other types of documents and even applications.
1.2. Audience
This section is non-normative.
This specification is intended for authors of documents and scripts that use the features defined in this specification, implementors of tools that operate on pages that use the features defined in this specification, and individuals wishing to establish the correctness of documents or implementations with respect to the requirements of this specification.
This document is probably not suited to readers who do not already have at least a passing familiarity with Web technologies, as in places it sacrifices clarity for precision, and brevity for completeness. More approachable tutorials and authoring guides can provide a gentler introduction to the topic.
In particular, familiarity with the basics of DOM is necessary for a complete understanding of some of the more technical parts of this specification. An understanding of Web IDL, HTTP, XML, Unicode, character encodings, JavaScript, and CSS will also be helpful in places but is not essential.
1.3. Scope
This section is non-normative.
This specification is limited to providing a semantic-level markup language and associated semantic-level scripting APIs for authoring accessible pages on the Web ranging from static documents to dynamic applications.
The scope of this specification does not include providing mechanisms for media-specific customization of presentation (although default rendering rules for Web browsers are included at the end of this specification, and several mechanisms for hooking into CSS are provided as part of the language).
The scope of this specification is not to describe an entire operating system. In particular, hardware configuration software, image manipulation tools, and applications that users would be expected to use with high-end workstations on a daily basis are out of scope. In terms of applications, this specification is targeted specifically at applications that would be expected to be used by users on an occasional basis, or regularly but from disparate locations, with low CPU requirements. Examples of such applications include online purchasing systems, searching systems, games (especially multiplayer online games), public telephone books or address books, communications software (e-mail clients, instant messaging clients, discussion software), document editing software, etc.
1.4. History
This section is non-normative.
For its first five years (1990-1995), HTML went through a number of revisions and experienced a number of extensions, primarily hosted first at CERN, and then at the IETF.
With the creation of the W3C, HTML’s development changed venue again. A first abortive attempt at extending HTML in 1995 known as HTML 3.0 then made way to a more pragmatic approach known as HTML 3.2, which was completed in 1997. HTML 4.01 quickly followed later that same year.
The following year, the W3C membership decided to stop evolving HTML and instead begin work on an XML-based equivalent, called XHTML. This effort started with a reformulation of HTML 4.01 in XML, known as XHTML 1.0, which added no new features except the new serialization, and which was completed in 2000. After XHTML 1.0, the W3C’s focus turned to making it easier for other working groups to extend XHTML, under the banner of XHTML Modularization. In parallel with this, the W3C also worked on a new language that was not compatible with the earlier HTML and XHTML languages, calling it XHTML 2.0.
Around the time that HTML’s evolution was stopped in 1998, parts of the API for HTML developed by browser vendors were specified and published under the name DOM Level 1 (in 1998) and DOM Level 2 Core and DOM Level 2 HTML (starting in 2000 and culminating in 2003). These efforts then petered out, with some DOM Level 3 specifications published in 2004 but the working group being closed before all the Level 3 drafts were completed.
In 2003, the publication of XForms, a technology which was positioned as the next generation of Web forms, sparked a renewed interest in evolving HTML itself, rather than finding replacements for it. This interest was borne from the realization that XML’s deployment as a Web technology was limited to entirely new technologies (like RSS and later Atom), rather than as a replacement for existing deployed technologies (like HTML).
A proof of concept to show that it was possible to extend HTML 4.01’s forms to provide many of the features that XForms 1.0 introduced, without requiring browsers to implement rendering engines that were incompatible with existing HTML Web pages, was the first result of this renewed interest. At this early stage, while the draft was already publicly available, and input was already being solicited from all sources, the specification was only under Opera Software’s copyright.
The idea that HTML’s evolution should be reopened was tested at a W3C workshop in 2004, where some of the principles that underlie the HTML work (described below), as well as the aforementioned early draft proposal covering just forms-related features, were presented to the W3C jointly by Mozilla and Opera. The proposal was rejected on the grounds that the proposal conflicted with the previously chosen direction for the Web’s evolution; the W3C staff and membership voted to continue developing XML-based replacements instead.
Shortly thereafter, Apple, Mozilla, and Opera jointly announced their intent to continue working on the effort under the umbrella of a new venue called the WHATWG. A public mailing list was created, and the draft was moved to the WHATWG site. The copyright was subsequently amended to be jointly owned by all three vendors, and to allow reuse of the specification.
The WHATWG was based on several core principles, in particular that technologies need to be backwards compatible, that specifications and implementations need to match even if this means changing the specification rather than the implementations, and that specifications need to be detailed enough that implementations can achieve complete interoperability without reverse-engineering each other.
The latter requirement in particular required that the scope of the HTML specification include what had previously been specified in three separate documents: HTML 4.01, XHTML 1.1, and DOM Level 2 HTML. It also meant including significantly more detail than had previously been considered the norm.
In 2006, the W3C indicated an interest to participate in the development of HTML 5.0 after all, and in 2007 formed a working group chartered to work with the WHATWG on the development of the HTML specification. Apple, Mozilla, and Opera allowed the W3C to publish the specification under the W3C copyright, while keeping a version with the less restrictive license on the WHATWG site.
For a number of years, both groups then worked together under the same editor: Ian Hickson. In 2011, the groups came to the conclusion that they had different goals: the W3C wanted to draw a line in the sand for features for a HTML 5.0 Recommendation, while the WHATWG wanted to continue working on a Continually Updated Specification for HTML, continuously maintaining the specification and adding new features. In mid 2012, a new editing team was introduced at the W3C to take care of creating a HTML 5.0 Recommendation and prepare a Working Draft for the next HTML version.
Since then, the W3C HTML WG has been cherry picking patches from the WHATWG that resolved bugs registered on the W3C HTML specification or more accurately represented implemented reality in user agents. At time of publication of this document, patches from the WHATWG HTML specification have been merged until January 12, 2016. The W3C HTML editors have also added patches that resulted from discussions and decisions made by the W3C HTML WG as well a bug fixes from bugs not shared by the WHATWG.
A separate document is published to document the differences between the HTML specified in this document and the language described in the HTML 4.01 specification. [HTML5-DIFF]
1.5. Design notes
This section is non-normative.
It must be admitted that many aspects of HTML appear at first glance to be nonsensical and inconsistent.
HTML, its supporting DOM APIs, as well as many of its supporting technologies, have been developed over a period of several decades by a wide array of people with different priorities who, in many cases, did not know of each other’s existence.
Features have thus arisen from many sources, and have not always been designed in especially consistent ways. Furthermore, because of the unique characteristics of the Web, implementation bugs have often become de-facto, and now de-jure, standards, as content is often unintentionally written in ways that rely on them before they can be fixed.
Despite all this, efforts have been made to adhere to certain design goals. These are described in the next few subsections.
1.5.1. Serializability of script execution
This section is non-normative.
To avoid exposing Web authors to the complexities of multithreading, the HTML and DOM APIs are
designed such that no script can ever detect the simultaneous execution of other scripts. Even
with workers
, the intent is that the behavior of implementations
can be thought of as completely serializing the execution of all scripts in all browsing contexts.
1.5.2. Compliance with other specifications
This section is non-normative.
This specification interacts with and relies on a wide variety of other specifications. In certain circumstances, unfortunately, conflicting needs have led to this specification violating the requirements of these other specifications. Whenever this has occurred, the transgressions have each been noted as a "willful violation", and the reason for the violation has been noted.
1.5.3. Extensibility
This section is non-normative.
HTML has a wide array of extensibility mechanisms that can be used for adding semantics in a safe manner:
-
Authors can use the
class
attribute to extend elements, effectively creating their own elements, while using the most applicable existing "real" HTML element, so that browsers and other tools that don’t know of the extension can still support it somewhat well. This is the tack used by microformats, for example. -
Authors can include data for inline client-side scripts or server-side site-wide scripts to process using the
data-*=""
attributes. These are guaranteed to never be touched by browsers, and allow scripts to include data on HTML elements that scripts can then look for and process. -
Authors can use the
meta name="" content=""
mechanism to include page-wide metadata by registering extensions to the predefined set of metadata names. -
Authors can use the
rel=""
mechanism to annotate links with specific meanings by registering extensions to the predefined set of link types. This is also used by microformats. -
Authors can embed raw data using the
script type=""
mechanism with a custom type, for further handling by inline or server-side scripts. -
Authors can create plugins and invoke them using the
embed
element. This is how Flash works. -
Authors can extend APIs using the JavaScript prototyping mechanism. This is widely used by script libraries, for instance.
1.6. HTML vs XHTML
This section is non-normative.
This specification defines an abstract language for describing documents and applications, and some APIs for interacting with in-memory representations of resources that use this language.
The in-memory representation is known as "DOM HTML", or "the DOM" for short.
There are various concrete syntaxes that can be used to transmit resources that use this abstract language, two of which are defined in this specification.
The first such concrete syntax is the HTML syntax. This is the format suggested for most authors.
It is compatible with most legacy Web browsers. If a document is transmitted with the text/html
MIME type, then it will be processed as an
HTML document by Web browsers. This specification defines the latest version of the HTML syntax,
known as "HTML 5.1".
The second concrete syntax is the XHTML syntax, which is an application of XML. When a document
is transmitted with an XML MIME type, such as application/xhtml+xml
, then it is treated as an
XML document by Web browsers, to be parsed by an XML processor. Authors are reminded that the
processing for XML and HTML differs; in particular, even minor syntax errors will prevent a
document labeled as XML from being rendered fully, whereas they would be ignored in the HTML
syntax. This specification defines the latest version of the XHTML syntax, known as "XHTML
5.1".
The DOM, the HTML syntax, and the XHTML syntax cannot all represent the same content. For
example, namespaces cannot be represented using the HTML syntax, but they are supported in the
DOM and in the XHTML syntax. Similarly, documents that use the noscript
feature can
be represented using the HTML syntax, but cannot be represented with the DOM or in the XHTML
syntax. Comments that contain the string "-->
" can only be represented in the
DOM, not in the HTML and XHTML syntaxes.
1.7. Structure of this specification
This section is non-normative.
This specification is divided into the following major sections:
-
Non-normative materials providing a context for the HTML standard.
-
The conformance classes, algorithms, definitions, and the common underpinnings of the rest of the specification.
-
Documents are built from elements. These elements form a tree using the DOM. This section defines the features of this DOM, as well as introducing the features common to all elements, and the concepts used in defining elements.
-
Each element has a predefined meaning, which is explained in this section. Rules for authors on how to use the element, along with user agent requirements for how to handle each element, are also given. This includes large signature features of HTML such as video playback and subtitles, form controls and form submission, and a 2D graphics API known as the HTML canvas.
-
HTML documents can provide a number of mechanisms for users to interact with and modify content, which are described in this section, such as how focus works, and drag-and-drop.
-
HTML documents do not exist in a vacuum — this section defines many of the features that affect environments that deal with multiple pages, such as Web browsers and offline caching of Web applications.
-
This section introduces basic features for scripting of applications in HTML.
-
-
All of these features would be for naught if they couldn’t be represented in a serialized form and sent to other people, and so these sections define the syntaxes of HTML and XHTML, along with rules for how to parse content using those syntaxes.
-
This section defines the default rendering rules for Web browsers.
There are also some appendices, listing §11 Obsolete features and §12 IANA considerations, and several indices.
1.7.1. How to read this specification
This specification should be read like all other specifications. First, it should be read cover-to-cover, multiple times. Then, it should be read backwards at least once. Then it should be read by picking random sections from the contents list and following all the cross-references.
As described in the conformance requirements section below, this specification describes conformance criteria for a variety of conformance classes. In particular, there are conformance requirements that apply to producers, for example authors and the documents they create, and there are conformance requirements that apply to consumers, for example Web browsers. They can be distinguished by what they are requiring: a requirement on a producer states what is allowed, while a requirement on a consumer states how software is to act.
foo
attribute’s value must be a valid integer" is a
requirement on producers, as it lays out the allowed values; in contrast, the requirement "the foo
attribute’s value must be parsed using the rules for parsing integers"
is a requirement on consumers, as it describes how to process the content. Requirements on producers have no bearing whatsoever on consumers.
1.7.2. Typographic conventions
This is a note.
This is an open issue.
This is a warning.
interface Example { // this is an IDL definition };
- variable = object .
method
( [ optionalArgument ] ) - This is a note to authors describing the usage of an interface.
/* this is a CSS fragment */
The defining instance of a term is marked up like this. Uses of that term are marked up like this or like this.
The defining instance of an element, attribute, or API is marked up like this
. References to that element, attribute, or API are
marked up like this
.
Other code fragments are marked up like this
.
Byte sequences with bytes in the range 0x00 to 0x7F, inclusive, are marked up like
`this
`.
Variables are marked up like this.
In an algorithm, steps in synchronous sections are marked with ⌛.
In some cases, requirements are given in the form of lists with conditions and corresponding requirements. In such cases, the requirements that apply to a condition are always the first set of requirements that follow the condition, even in the case of there being multiple sets of conditions for those requirements. Such cases are presented as follows:
- This is a condition
- This is another condition
- This is the requirement that applies to the conditions above.
- This is a third condition
- This is the requirement that applies to the third condition.
1.8. Privacy concerns
This section is non-normative.
Some features of HTML trade user convenience for a measure of user privacy.
In general, due to the Internet’s architecture, a user can be distinguished from another by the user’s IP address. IP addresses do not perfectly match to a user; as a user moves from device to device, or from network to network, their IP address will change; similarly, NAT routing, proxy servers, and shared computers enable packets that appear to all come from a single IP address to actually map to multiple users. Technologies such as onion routing can be used to further anonymize requests so that requests from a single user at one node on the Internet appear to come from many disparate parts of the network.
However, the IP address used for a user’s requests is not the only mechanism by which a user’s requests could be related to each other.
Cookies, for example, are designed specifically to enable this, and are the basis of most of the Web’s session features that enable you to log into a site with which you have an account.
Application caches have similar implications with respect to privacy, for example if the site can identify the user when providing the cache, it can store data in the cache that can be used for cookie resurrection.
There are other mechanisms that are more subtle. Certain characteristics of a user’s system can be used to distinguish groups of users from each other; by collecting enough such information, an individual user’s browser’s "digital fingerprint" can be computed, which can be as good, if not better, as an IP address in ascertaining which requests are from the same user.
Grouping requests in this manner, especially across multiple sites, can be used for both benign (and even arguably positive) purposes, as well as for malevolent purposes. An example of a reasonably benign purpose would be determining whether a particular person seems to prefer sites with dog illustrations as opposed to sites with cat illustrations (based on how often they visit the sites in question) and then automatically using the preferred illustrations on subsequent visits to participating sites. Malevolent purposes, however, could include governments combining information such as the person’s home address (determined from the addresses they use when getting driving directions on one site) with their apparent political affiliations (determined by examining the forum sites that they participate in) to determine whether the person should be prevented from voting in an election.
Since the malevolent purposes can be remarkably evil, user agent implementors are encouraged to consider how to provide their users with tools to minimize leaking information that could be used to fingerprint a user.
Unfortunately, as the first paragraph in this section implies, sometimes there is great benefit to be derived from exposing the very information that can also be used for fingerprinting purposes, so it’s not as easy as simply blocking all possible leaks. For instance, the ability to log into a site to post under a specific identity requires that the user’s requests be identifiable as all being from the same user. More subtly, though, information such as how wide text is, which is necessary for many effects that involve drawing text onto a canvas (e.g., any effect that involves drawing a border around the text) also leaks information that can be used to group a user’s requests. (In this case, by potentially exposing, via a brute force search, which fonts a user has installed, information which can vary considerably from user to user.)
Features in this specification which can be used to fingerprint the user are marked as
this paragraph is.
Other features in the platform can be used for the same purpose, though, including, though not limited to:
-
The exact list of which features a user agents supports.
-
The maximum allowed stack depth for recursion in script.
-
Features that describe the user’s environment, like Media Queries and the
Screen
object. [MEDIAQ] [CSSOM-VIEW] -
The user’s time zone.
1.9. A quick introduction to HTML
This section is non-normative.
A basic HTML document looks like this:
<!DOCTYPE html> <html> <head> <title>Sample page</title> </head> <body> <h1>Sample page</h1> <p>This is a <a href="demo.html">simple</a> sample.</p> <!-- this is a comment --> </body> </html>
HTML documents consist of a tree of elements and text. Each element is denoted in the source by
a start tag, such as "<body>
", and an end tag, such as
"</body>
". (Certain start tags and end tags can in certain cases be omitted and are implied by other tags.)
Tags have to be nested such that elements are all completely within each other, without overlapping:
<p>This is <em>very <strong>wrong</em>!</strong></p>
<p>This <em>is <strong>correct</strong>.</em></p>
This specification defines a set of elements that can be used in HTML, along with rules about the ways in which the elements can be nested.
Elements can have attributes, which control how the elements work. In the example below, there
is a hyperlink, formed using the a
element and its href
attribute:
<a href="demo.html">simple</a>
Attributes are placed inside the start tag, and consist of a name and a value, separated by an
"=
" character. The attribute value can remain unquoted if it doesn’t contain space characters or any of "
'
`
=
<
or >
. Otherwise, it has to be quoted using either single or
double quotes. The value, along with the "=
" character, can be omitted altogether if
the value is the empty string.
<!-- empty attributes --> <input name=address disabled> <input name=address disabled=""> <!-- attributes with a value --> <input name=address maxlength=200> <input name=address maxlength='200'> <input name=address maxlength="200">
HTML user agents (e.g., Web browsers) then parse this markup, turning it into a DOM (Document Object Model) tree. A DOM tree is an in-memory representation of a document.
DOM trees contain several kinds of nodes, in particular a DocumentType
node, Element
nodes, Text
nodes, Comment
nodes, and in some cases ProcessingInstruction
nodes.
The markup snippet at the top of this section would be turned into the following DOM tree:
- DOCTYPE:
html
-
html
The root element of this tree is the html
element, which is the element always found at
the root of HTML documents. It contains two elements, head
and body
, as well as a Text
node between them.
There are many more Text
nodes in the DOM tree than one would initially expect,
because the source contains a number of spaces (represented here by "␣") and line breaks
("⏎") that all end up as Text
nodes in the DOM. However, for historical
reasons not all of the spaces and line breaks in the original markup appear in the DOM. In
particular, all the whitespace before head
start tag ends up being dropped silently, and all
the whitespace after the body
end tag ends up placed at the end of the body
.
The head
element contains a title
element, which itself
contains a Text
node with the text "Sample page". Similarly, the body
element
contains an h1
element, a p
element, and a comment.
This DOM tree can be manipulated from scripts in the page. Scripts (typically in JavaScript)
are small programs that can be embedded using the script
element or using event handler content attributes. For example, here is a form with a script that sets the
value of the form’s output
element to say "Hello World"
<form name="main"> Result: <output name="result"></output> <script> document.forms.main.elements.result.value = 'Hello World'; </script> </form>
Each element in the DOM tree is represented by an object, and these objects have APIs so that
they can be manipulated. For instance, a link (e.g., the a
element in the tree above) can have
its "href
" attribute changed in several ways:
var a = document.links[0]; // obtain the first link in the document a.href = 'sample.html'; // change the destination URL of the link a.protocol = 'https'; // change just the scheme part of the URL a.setAttribute('href', 'https://example.com/'); // change the content attribute directly
Since DOM trees are used as the way to represent HTML documents when they are processed and presented by implementations (especially interactive implementations like Web browsers), this specification is mostly phrased in terms of DOM trees, instead of the markup described above.
HTML documents represent a media-independent description of interactive content. HTML documents might be rendered to a screen, or through a speech synthesizer, or on a braille display. To influence exactly how such rendering takes place, authors can use a styling language such as CSS.
In the following example, the page has been made yellow-on-blue using CSS.
<!DOCTYPE html> <html> <head> <title>Sample styled page</title> <style> body { background: navy; color: yellow; } </style> </head> <body> <h1>Sample styled page</h1> <p>This page is just a demo.</p> </body> </html>
For more details on how to use HTML, authors are encouraged to consult tutorials and guides. Some of the examples included in this specification might also be of use, but the novice author is cautioned that this specification, by necessity, defines the language with a level of detail that might be difficult to understand at first.
1.9.1. Writing secure applications with HTML
This section is non-normative.
When HTML is used to create interactive sites, care needs to be taken to avoid introducing vulnerabilities through which attackers can compromise the integrity of the site itself or of the site’s users.
A comprehensive study of this matter is beyond the scope of this document, and authors are strongly encouraged to study the matter in more detail. However, this section attempts to provide a quick introduction to some common pitfalls in HTML application development.
The security model of the Web is based on the concept of "origins", and correspondingly many of the potential attacks on the Web involve cross-origin actions. [ORIGIN]
-
Not validating user input
Cross-site scripting (XSS)
SQL injection
-
When accepting untrusted input, e.g., user-generated content such as text comments, values in URL parameters, messages from third-party sites, etc, it is imperative that the data be validated before use, and properly escaped when displayed. Failing to do this can allow a hostile user to perform a variety of attacks, ranging from the potentially benign, such as providing bogus user information like a negative age, to the serious, such as running scripts every time a user looks at a page that includes the information, potentially propagating the attack in the process, to the catastrophic, such as deleting all data in the server.
When writing filters to validate user input, it is imperative that filters always be safelist-based, allowing known-safe constructs and disallowing all other input. Blocklist-based filters that disallow known-bad inputs and allow everything else are not secure, as not everything that is bad is yet known (for example, because it might be invented in the future).
For example, suppose a page looked at its URL’s query string to determine what to display, and the site then redirected the user to that page to display a message, as in:<ul> <li><a href="message.cgi?say=Hello">Say Hello</a> <li><a href="message.cgi?say=Welcome">Say Welcome</a> <li><a href="message.cgi?say=Kittens">Say Kittens</a> </ul>
If the message was just displayed to the user without escaping, a hostile attacker could then craft a URL that contained a script element:
https://example.com/message.cgi?say=%3Cscript%3Ealert%28%27Oh%20no%21%27%29%3C/script%3E
If the attacker then convinced a victim user to visit this page, a script of the attacker’s choosing would run on the page. Such a script could do any number of hostile actions, limited only by what the site offers: if the site is an e-commerce shop, for instance, such a script could cause the user to unknowingly make arbitrarily many unwanted purchases.
This is called a cross-site scripting attack.
There are many constructs that can be used to try to trick a site into executing code. Here are some that authors are encouraged to consider when writing safelist filters:
-
When allowing harmless-seeming elements like
img
, exercise the principle of least-privilege and limit the element’s attributes to only those that are needed (e.g., via a safelist). If one allowed all attributes then an attacker could, for instance, use theonload
attribute to run arbitrary script. -
When allowing URLs to be provided (e.g., for links), the scheme of each URL also needs to be explicitly safelisted, as there are many schemes that can be abused. The most prominent example is "
javascript:
", but user agents can implement (and indeed, have historically implemented) others. -
Allowing a
base
element to be inserted means anyscript
elements in the page with relative links can be hijacked, and similarly that any form submissions can get redirected to a hostile site.
-
-
Cross-site request forgery (CSRF)
-
If a site allows a user to make form submissions with user-specific side-effects, for example posting messages on a forum under the user’s name, making purchases, or applying for a passport, it is important to verify that the request was made by the user intentionally, rather than by another site tricking the user into making the request unknowingly.
This problem exists because HTML forms can be submitted to other origins.
Sites can prevent such attacks by populating forms with user-specific hidden tokens, or by checking
Origin
headers on all requests. -
Clickjacking
-
A page that provides users with an interface to perform actions that the user might not wish to perform needs to be designed so as to avoid the possibility that users can be tricked into activating the interface.
One way that a user could be so tricked is if a hostile site places the victim site in a small
iframe
and then convinces the user to click, for instance by having the user play a reaction game. Once the user is playing the game, the hostile site can quickly position theiframe
under the mouse cursor just as the user is about to click, thus tricking the user into clicking the victim site’s interface.To avoid this, sites that do not expect to be used in frames are encouraged to only enable their interface if they detect that they are not in a frame (e.g., by comparing the
Window
object to the value of thetop
attribute).
1.9.2. Common pitfalls to avoid when using the scripting APIs
This section is non-normative.
Scripts in HTML have "run-to-completion" semantics, meaning that the browser will generally run the script uninterrupted before doing anything else, such as firing further events or continuing to parse the document.
On the other hand, parsing of HTML files happens in parallel and incrementally, meaning that the parser can pause at any point to let scripts run. This is generally a good thing, but it does mean that authors need to be careful to avoid hooking event handlers after the events could have possibly fired.
There are two techniques for doing this reliably: use event handler content attributes, or create the element and add the event handlers in the same script. The latter is safe because, as mentioned earlier, scripts are run to completion before further events can fire.
img
elements and the load
event.
The event could fire as soon as the element has been parsed, especially if the image has already
been cached (which is common).
Here, the author uses the onload
handler
on an img
element to catch the load
event:
<img src="games.png" alt="Games" onload="gamesLogoHasLoaded(event)">
If the element is being added by script, then so long as the event handlers are added in the same script, the event will still not be missed:
<script> var img = new Image(); img.src = 'games.png'; img.alt = 'Games'; img.onload = gamesLogoHasLoaded; // img.addEventListener('load', gamesLogoHasLoaded, false); // would work also </script>
However, if the author first created the img
element and then in a separate
script added the event listeners, there’s a chance that the load
event would be
fired in between, leading it to be missed:
<!-- Do not use this style, it has a race condition! --> <img id="games" src="games.png" alt="Games"> <!-- the 'load' event might fire here while the parser is taking a break, in which case you will not see it! --> <script> var img = document.getElementById('games'); img.onload = gamesLogoHasLoaded; // might never fire! </script>
1.9.3. How to catch mistakes when writing HTML: validators and conformance checkers
This section is non-normative.
Authors are encouraged to make use of conformance checkers (also known as validators) to catch common mistakes. The W3C provides a number of online validation services, including the Nu Markup Validation Service.
1.10. Conformance requirements for authors
This section is non-normative.
Unlike previous versions of the HTML specification, this specification defines in some detail the required processing for invalid documents as well as valid documents.
However, even though the processing of invalid content is in most cases well-defined, conformance requirements for documents are still important: in practice, interoperability (the situation in which all implementations process particular content in a reliable and identical or equivalent way) is not the only goal of document conformance requirements. This section details some of the more common reasons for still distinguishing between a conforming document and one with errors.
1.10.1. Presentational markup
This section is non-normative.
The majority of presentational features from previous versions of HTML are no longer allowed. Presentational markup in general has been found to have a number of problems:
-
The use of presentational elements leads to poorer accessibility
-
While it is possible to use presentational markup in a way that provides users of assistive technologies (ATs) with an acceptable experience (e.g., using ARIA), doing so is significantly more difficult than doing so when using semantically-appropriate markup. Furthermore, presentational markup does not guarantee accessibility for users of non-AT, non-graphical user agents (such as text-mode browsers).
Using media-independent markup, on the other hand, provides an easy way for documents to be authored in such a way that they are "accessible" for more users (e.g., users of text browsers).
-
Higher cost of maintenance
-
It is significantly easier to maintain a site written in such a way that the markup is style-independent. For example, changing the color of a site that uses
<font color="">
throughout requires changes across the entire site, whereas a similar change to a site based on CSS can be done by changing a single file. -
Larger document sizes
-
Presentational markup tends to be much more redundant, and thus results in larger document sizes.
For those reasons, presentational markup has been removed from HTML in this version. This change should not come as a surprise; HTML 4.0 deprecated presentational markup many years ago and provided a mode (HTML Transitional) to help authors move away from presentational markup; later, XHTML 1.1 went further and obsoleted those features altogether.
The only remaining presentational markup features in HTML are the style
attribute
and the style
element. Use of the style
attribute is somewhat discouraged in
production environments, but it can be useful for rapid prototyping (where its rules can be
directly moved into a separate style sheet later) and for providing specific styles in unusual
cases where a separate style sheet would be inconvenient. Similarly, the style
element can
be useful for grouping or for page-specific styles, but in general an external style sheet
is likely to be more convenient when the styles apply to multiple pages.
It is also worth noting that some elements that were previously presentational have been
redefined in this specification to be media-independent: b
, i
, hr
, s
, small
, and u
.
1.10.2. Syntax errors
This section is non-normative.
The syntax of HTML is constrained to avoid a wide variety of problems.
-
Unintuitive error-handling behavior
-
Certain invalid syntax constructs, when parsed, result in DOM trees that are highly unintuitive.
-
Errors with optional error recovery
-
To allow user agents to be used in controlled environments without having to implement the more bizarre and convoluted error handling rules, user agents are permitted to fail whenever encountering a parse error.
-
Errors where the error-handling behavior is not compatible with streaming user agents
-
Some error-handling behavior, such as the behavior for the
<table><hr>...
example mentioned above, are incompatible with streaming user agents (user agents that process HTML files in one pass, without storing state). To avoid interoperability problems with such user agents, any syntax resulting in such behavior is considered invalid. -
Errors that can result in infoset coercion
-
When a user agent based on XML is connected to an HTML parser, it is possible that certain invariants that XML enforces, such as comments never containing two consecutive hyphens, will be violated by an HTML file. Handling this can require that the parser coerce the HTML DOM into an XML-compatible infoset. Most syntax constructs that require such handling are considered invalid.
-
Errors that result in disproportionately poor performance
-
Certain syntax constructs can result in disproportionately poor performance. To discourage the use of such constructs, they are typically made non-conforming.
For example, the following markup results in poor performance, since all the unclosedi
elements have to be reconstructed in each paragraph, resulting in progressively more elements in each paragraph:<p><i>He dreamt. <p><i>He dreamt that he ate breakfast. <p><i>Then lunch. <p><i>And finally dinner.
The resulting DOM for this fragment would be:
-
Errors involving fragile syntax constructs
-
There are syntax constructs that, for historical reasons, are relatively fragile. To help reduce the number of users who accidentally run into such problems, they are made non-conforming.
For example, the parsing of certain named character references in attributes happens even with the closing semicolon being omitted. It is safe to include an ampersand followed by letters that do not form a named character reference, but if the letters are changed to a string that does form a named character reference, they will be interpreted as that character instead.In this fragment, the attribute’s value is "
?bill&ted
":<a href="?bill&ted">Bill and Ted</a>
In the following fragment, however, the attribute’s value is actually "
?art©
", not the intended "?art©
", because even without the final semicolon, "©
" is handled the same as "©
" and thus gets interpreted as "©
":<a href="?art©">Art and Copy</a>
To avoid this problem, all named character references are required to end with a semicolon, and uses of named character references without a semicolon are flagged as errors.
Thus, the correct way to express the above cases is as follows:
<a href="?bill&ted">Bill and Ted</a> <!-- &ted is ok, since it’s not a named character reference -->
<a href="?art&copy">Art and Copy</a> <!-- the & has to be escaped, since © is a named character reference -->
-
Errors involving known interoperability problems in legacy user agents
-
Certain syntax constructs are known to cause especially subtle or serious problems in legacy user agents, and are therefore marked as non-conforming to help authors avoid them.
For example, this is why the U+0060 GRAVE ACCENT character (`) is not allowed in unquoted attributes. In certain legacy user agents, it is sometimes treated as a quote character.
Another example of this is the DOCTYPE, which is required to trigger no-quirks mode, because the behavior of legacy user agents in quirks mode is often largely undocumented.
-
Errors that risk exposing authors to security attacks
-
Certain restrictions exist purely to avoid known security problems.
For example, the restriction on using UTF-7 exists purely to avoid authors falling prey to a known cross-site-scripting attack using UTF-7. [RFC2152]
-
Cases where the author’s intent is unclear
-
Markup where the author’s intent is very unclear is often made non-conforming. Correcting these errors early makes later maintenance easier.
For example, it is unclear whether the author intended the following to be an
h1
heading or anh2
heading:<h2>Contact details</h1>
-
Cases that are likely to be typos
-
When a user makes a simple typo, it is helpful if the error can be caught early, as this can save the author a lot of debugging time. This specification therefore usually considers it an error to use element names, attribute names, and so forth, that do not match the names defined in this specification.
For example, if the author typed
<capton>
instead of<caption>
, this would be flagged as an error and the author could correct the typo immediately. -
Errors that could interfere with new syntax in the future
-
In order to allow the language syntax to be extended in the future, certain otherwise harmless features are disallowed.
For example, attributes in end tags are currently invalid and ignored. A future change to the language may make use of this syntax feature and can do so without conflicting with already-deployed (and valid!) content.
Some authors find it helpful to be in the practice of always quoting all attributes and always including all optional tags, preferring the consistency derived from such custom over the minor benefits of terseness afforded by making use of the flexibility of the HTML syntax. To aid such authors, conformance checkers can provide modes of operation wherein such conventions are enforced.
1.10.3. Restrictions on content models and on attribute values
This section is non-normative.
Beyond the syntax of the language, this specification also places restrictions on how elements and attributes can be specified. These restrictions are present for similar reasons:
-
Errors involving content with dubious semantics
-
To avoid misuse of elements with defined meanings, content models are defined that restrict how elements can be nested when such nestings would be of dubious value.
For example, this specification disallows nesting a
section
element inside akbd
element, since it is highly unlikely for an author to indicate that an entire section should be keyed in. -
Errors that involve a conflict in expressed semantics
-
Similarly, to draw the author’s attention to mistakes in the use of elements, clear contradictions in the semantics expressed are also considered conformance errors.
In the fragments below, for example, the semantics are nonsensical: a separator cannot simultaneously be a cell, nor can a radio button be a progress bar.<hr role="cell">
<input type=radio role=progressbar>
Another example is the restrictions on the content models of the
ul
element, which only allowsli
element children. Lists by definition consist just of zero or more list items, so if aul
element contains something other than anli
element, it’s not clear what was meant. -
Cases where the default styles are likely to lead to confusion
-
Certain elements have default styles or behaviors that make certain combinations likely to lead to confusion. Where these have equivalent alternatives without this problem, the confusing combinations are disallowed.
For example,
div
elements are rendered as block boxes, andspan
elements as inline boxes. Putting a block box in an inline box is unnecessarily confusing; since either nesting justdiv
elements, or nesting justspan
elements, or nestingspan
elements insidediv
elements all serve the same purpose as nesting adiv
element in aspan
element, but only the latter involves a block box in an inline box, the latter combination is disallowed.Another example would be the way interactive content cannot be nested. For example, a
button
element cannot contain atextarea
element. This is because the default behavior of such nesting interactive elements would be highly confusing to users. Instead of nesting these elements, they can be placed side by side. -
Errors that indicate a likely misunderstanding of the specification
-
Sometimes, something is disallowed because allowing it would likely cause author confusion.
For example, setting the
disabled
attribute to the value "false
" is disallowed, because despite the appearance of meaning that the element is enabled, it in fact means that the element is disabled (what matters for implementations is the presence of the attribute, not its value). -
Errors involving limits that have been imposed merely to simplify the language
-
Some conformance errors simplify the language that authors need to learn.
For example, the
area
element’sshape
attribute, despite accepting bothcirc
andcircle
values in practice as synonyms, disallows the use of thecirc
value, so as to simplify tutorials and other learning aids. There would be no benefit to allowing both, but it would cause extra confusion when teaching the language. -
Errors that involve peculiarities of the parser
-
Certain elements are parsed in somewhat eccentric ways (typically for historical reasons), and their content model restrictions are intended to avoid exposing the author to these issues.
For example, aform
element isn’t allowed inside phrasing content, because when parsed as HTML, aform
element’s start tag will imply ap
element’s end tag. Thus, the following markup results in two paragraphs, not one:<p>Welcome. <form><label>Name:</label> <input></form>
It is parsed exactly like the following:
<p>Welcome. </p><form><label>Name:</label> <input></form>
-
Errors that would likely result in scripts failing in hard-to-debug ways
-
Some errors are intended to help prevent script problems that would be hard to debug.
This is why, for instance, it is non-conforming to have two
id
attributes with the same value. Duplicate IDs lead to the wrong element being selected, with sometimes disastrous effects whose cause is hard to determine. -
Errors that waste authoring time
-
Some constructs are disallowed because historically they have been the cause of a lot of wasted authoring time, and by encouraging authors to avoid making them, authors can save time in future efforts.
For example, a
script
element’ssrc
attribute causes the element’s contents to be ignored. However, this isn’t obvious, especially if the element’s contents appear to be executable script — which can lead to authors spending a lot of time trying to debug the inline script without realizing that it is not executing. To reduce this problem, this specification makes it non-conforming to have executable script in ascript
element when thesrc
attribute is present. This means that authors who are validating their documents are less likely to waste time with this kind of mistake. -
Errors that involve areas that affect authors migrating to and from XHTML
-
Some authors like to write files that can be interpreted as both XML and HTML with similar results. Though this practice is discouraged in general due to the myriad of subtle complications involved (especially when involving scripting, styling, or any kind of automated serialization), this specification has a few restrictions intended to at least somewhat mitigate the difficulties. This makes it easier for authors to use this as a transitionary step when migrating between HTML and XHTML.
For example, there are somewhat complicated rules surrounding the
lang
andxml:lang
attributes intended to keep the two synchronized.Another example would be the restrictions on the values of
xmlns
attributes in the HTML serialization, which are intended to ensure that elements in conforming documents end up in the same namespaces whether processed as HTML or XML. -
Errors that involve areas reserved for future expansion
-
As with the restrictions on the syntax intended to allow for new syntax in future revisions of the language, some restrictions on the content models of elements and values of attributes are intended to allow for future expansion of the HTML vocabulary.
For example, limiting the values of the
target
attribute that start with an U+005F LOW LINE character (_) to only specific predefined values allows new predefined values to be introduced at a future time without conflicting with author-defined values. -
Errors that indicate a mis-use of other specifications
-
Certain restrictions are intended to support the restrictions made by other specifications.
For example, requiring that attributes that take media query lists use only valid media query lists reinforces the importance of following the conformance rules of that specification.
1.11. Suggested reading
This section is non-normative.
The following documents might be of interest to readers of this specification.
-
Character Model for the World Wide Web 1.0: Fundamentals [CHARMOD]
-
This Architectural Specification provides authors of specifications, software developers, and content developers with a common reference for interoperable text manipulation on the World Wide Web, building on the Universal Character Set, defined jointly by the Unicode Standard and ISO/IEC 10646. Topics addressed include use of the terms "character", "encoding" and "string", a reference processing model, choice and identification of character encodings, character escaping, and string indexing.
-
Unicode Security Considerations [UNICODE-SECURITY]
-
Because Unicode contains such a large number of characters and incorporates the varied writing systems of the world, incorrect usage can expose programs or systems to possible security attacks. This is especially important as more and more products are internationalized. This document describes some of the security considerations that programmers, system analysts, standards developers, and users should take into account, and provides specific recommendations to reduce the risk of problems.
-
Web Content Accessibility Guidelines (WCAG) 2.0 [WCAG20]
-
Web Content Accessibility Guidelines (WCAG) 2.0 covers a wide range of recommendations for making Web content more accessible. Following these guidelines will make content accessible to a wider range of people with disabilities, including blindness and low vision, deafness and hearing loss, learning disabilities, cognitive limitations, limited movement, speech disabilities, photosensitivity and combinations of these. Following these guidelines will also often make your Web content more usable to users in general.
-
Authoring Tool Accessibility Guidelines (ATAG) 2.0 [ATAG20]
-
This specification provides guidelines for designing Web content authoring tools that are more accessible for people with disabilities. An authoring tool that conforms to these guidelines will promote accessibility by providing an accessible user interface to authors with disabilities as well as by enabling, supporting, and promoting the production of accessible Web content by all authors.
-
User Agent Accessibility Guidelines (UAAG) 2.0 [UAAG20]
-
This document provides guidelines for designing user agents that lower barriers to Web accessibility for people with disabilities. User agents include browsers and other types of software that retrieve and render Web content. A user agent that conforms to these guidelines will promote accessibility through its own user interface and through other internal facilities, including its ability to communicate with other technologies (especially assistive technologies). Furthermore, all users, not just users with disabilities, should find conforming user agents to be more usable.
-
Polyglot Markup: HTML-Compatible XHTML Documents [HTML-POLYGLOT]
-
A document that uses polyglot markup is a document that is a stream of bytes that parses into identical document trees (with the exception of the xmlns attribute on the root element) when processed as HTML and when processed as XML. Polyglot markup that meets a well defined set of constraints is interpreted as compatible, regardless of whether they are processed as HTML or as XHTML, per the HTML specification. Polyglot markup uses a specific DOCTYPE, namespace declarations, and a specific case — normally lower case but occasionally camel case — for element and attribute names. Polyglot markup uses lower case for certain attribute values. Further constraints include those on empty elements, named entity references, and the use of scripts and style.
-
HTML Accessibility APIs Mappings 1.0 [HTML-AAM-1.0]
-
Defines how user agents map HTML 5.1 elements and attributes to platform accessibility APIs. Documenting these mappings promotes interoperable exposure of roles, states, properties, and events implemented by accessibility APIs and helps to ensure that this information appears in a manner consistent with author intent.
2. Common infrastructure
2.1. Terminology
This specification refers to both HTML and XML attributes and IDL attributes, often in the same context. When it is not clear which is being referred to, they are referred to as content attributes for HTML and XML attributes, and IDL attributes for those defined on IDL interfaces. Similarly, the term "properties" is used for both JavaScript object properties and CSS properties. When these are ambiguous they are qualified as object properties and CSS properties respectively.
Generally, when the specification states that a feature applies to the HTML syntax or the XHTML syntax, it also includes the other. When a feature specifically only applies to one of the two languages, it is called out by explicitly stating that it does not apply to the other format, as in "for HTML, ... (this does not apply to XHTML)".
This specification uses the term document to refer to any use of HTML, ranging from
short static documents to long essays or reports with rich multimedia, as well as to fully-fledged
interactive applications. The term is used to refer both to Document
objects and
their descendant DOM trees, and to serialized byte streams using the HTML syntax or XHTML syntax, depending on context.
In the context of the DOM structures, the terms HTML document and XML document are
used as defined in the DOM specification, and refer specifically to two different modes that Document
objects can find themselves in. [DOM] (Such uses are always hyperlinked
to their definition.)
In the context of byte streams, the term HTML document refers to resources labeled as text/html
, and the term XML document refers to resources labeled with an XML MIME type.
The term XHTML document is used to refer to both documents in the XML document mode that contain element nodes in the HTML namespace, and byte streams labeled with an XML MIME type that contain elements from the HTML namespace, depending on context.
For simplicity, terms such as shown, displayed, and visible are used (sometimes) when referring to the way a document is rendered to the user. These terms are not meant to imply a visual medium; they must be considered to apply to other media in equivalent ways.
When an algorithm B says to return to another algorithm A, it implies that A called B. Upon returning to A, the implementation must continue from where it left off in calling B. Some algorithms run in parallel; this means that the algorithm’s subsequent steps are to be run, one after another, at the same time as other logic in the specification (e.g., at the same time as the event loop). This specification does not define the precise mechanism by which this is achieved, be it time-sharing cooperative multitasking, fibers, threads, processes, using different hyperthreads, cores, CPUs, machines, etc. By contrast, an operation that is to run immediately must interrupt the currently running task, run itself, and then resume the previously running task.
The term "transparent black" refers to the color with red, green, blue, and alpha channels all set to zero.
2.1.1. Resources
The specification uses the term supported when referring to whether a user agent has an implementation capable of decoding the semantics of an external resource. A format or type is said to be supported if the implementation can process an external resource of that format or type without critical aspects of the resource being ignored. Whether a specific resource is supported can depend on what features of the resource’s format are in use.
For example, a PNG image would be considered to be in a supported format if its pixel data could be decoded and rendered, even if, unbeknownst to the implementation, the image also contained animation data.
An MPEG-4 video file would not be considered to be in a supported format if the compression format used was not supported, even if the implementation could determine the dimensions of the movie from the file’s metadata.
What some specifications, in particular the HTTP specification, refer to as a representation is referred to in this specification as a resource. [HTTP]
The term MIME type is used to refer to what is sometimes called an Internet media type in protocol literature. The term media type in this specification is used to refer to the type of media intended for presentation, as used by the CSS specifications. [RFC2046] [MEDIAQ]
A string is a valid MIME type if it matches the media-type
rule. In particular, a valid mime type may include
MIME type parameters. [HTTP]
A string is a valid MIME type with no parameters if it matches the media-type
rule, but does not
contain any U+003B SEMICOLON characters (;). In other words, if it consists only of a type and
subtype, with no MIME Type parameters. [HTTP]
The term HTML MIME type is used to refer to the MIME type text/html
.
A resource’s critical subresources are those that the resource needs to have available to be correctly processed. Which resources are considered critical or not is defined by the specification that defines the resource’s format.
The term data:
URL refers to URLs that use the data:
scheme. [RFC2397]
2.1.2. XML
To ease migration from HTML to XHTML, user agents conforming to this specification will place elements in
HTML in the https://www.w3.org/1999/xhtml
namespace, at least for the purposes of the
DOM and CSS. The term "HTML elements", when used in this specification, refers to any
element in that namespace, and thus refers to both HTML and XHTML elements.
Except where otherwise stated, all elements defined or mentioned in this specification are in the HTML namespace ("https://www.w3.org/1999/xhtml
"), and all attributes defined or
mentioned in this specification have no namespace.
The term element type is used to refer to the set of elements that have a given local
name and namespace. For example, button
elements are elements with the element type button
, meaning they have the local name "button
" and (implicitly as
defined above) the HTML namespace.
Attribute names are said to be XML-compatible if they match the Name
production defined in XML and they contain no U+003A COLON characters
(:). [XML]
The term XML MIME type is used to refer to the MIME types text/xml
, application/xml
, and any MIME type whose subtype ends with the four characters
"+xml
". [RFC7303]
2.1.3. DOM trees
The root element of a Document
object is that Document
's
first element child, if any. If it does not have one then the Document
has no root
element.
The term root element, when not referring to a Document
object’s root
element, means the furthest ancestor element node of whatever node is being discussed, or the node
itself if it has no ancestors. When the node is a part of the document, then the node’s root element is indeed the document’s root element; however, if the node is not currently
part of the document tree, the root element will be an orphaned node.
When an element’s root element is the root element of a Document
object,
it is said to be in a Document
. An element is said to have been inserted into a document when its root element changes and is now the document’s root element. Analogously, an element is said to have been removed from a document when its root element changes from being the document’s root element to being another element.
A node’s home subtree is the subtree rooted at that node’s root element. When a
node is in a Document
, its home subtree is that Document
's tree.
The Document
of a Node
(such as an element) is the Document
that the Node
's ownerDocument
IDL attribute returns. When a Node
is in a Document
then that Document
is
always the Node
's Document
, and the Node
's ownerDocument
IDL attribute thus always returns that Document
.
The Document
of a content attribute is the Document
of the attribute’s
element.
The term tree order means a pre-order, depth-first traversal of DOM nodes involved
(through the parentNode
/childNodes
relationship).
When it is stated that some element or attribute is ignored, or treated as some other value, or handled as if it was something else, this refers only to the processing of the node after it is in the DOM. A user agent must not mutate the DOM in such situations.
A content attribute is said to change value only if its new value is different than its previous value; setting an attribute to a value it already has does not change it.
When an attribute value, Text
node, or string is described as empty, it means that the length of the text is zero (i.e., not even containing spaces or control characters).
An element’s child text content is the concatenation of the data of all the Text
nodes that are children of the element (ignoring any other nodes such as comments or
elements), in tree order.
A node A is inserted into a node B when the insertion steps are invoked with A as the argument and A’s new parent is B. Similarly, a node A is removed from a node B when the removing steps are invoked with A as the removedNode argument and B as the oldParent argument.
2.1.4. Scripting
The construction "a Foo
object", where Foo
is actually an interface,
is sometimes used instead of the more accurate "an object implementing the interface Foo
".
An IDL attribute is said to be getting when its value is being retrieved (e.g., by author script), and is said to be setting when a new value is assigned to it.
If a DOM object is said to be live, then the attributes and methods on that object must operate on the actual underlying data, not a snapshot of the data.
In the contexts of events, the terms fire and dispatch are used as defined in the
DOM specification: firing an event means to create and dispatch it, and dispatching an event means to follow the steps that propagate the event through the
tree. The term trusted event is used to refer to events whose isTrusted
attribute is initialized to true. [DOM]
2.1.5. Plugin
Content Handlers
The term plugin refers to a user-agent defined set of content
handlers that can be used by the user agent. The content handlers can take part in the user
agent’s rendering of a Document
object, but that neither act as child browsing contexts of the Document
nor introduce any Node
objects to the Document
's DOM.
Typically such content handlers are provided by third parties, though a user agent can also designate built-in content handlers as plugins.
A user agent must not consider the types text/plain
and application/octet-stream
as having a registered plugin.
One example of a plugin would be a PDF viewer that is instantiated in a browsing context when the user navigates to a PDF file. This would count as a plugin regardless of whether the party that implemented the PDF viewer component was the same as that which implemented the user agent itself. However, a PDF viewer application that launches separate from the user agent (as opposed to using the same interface) is not a plugin by this definition.
This specification does not define a mechanism for interacting with plugins, as it is expected to be user-agent- and platform-specific. Some user agents might opt to support a plugin mechanism such as the Netscape Plugin API; others might use remote content converters or have built-in support for certain types. Indeed, this specification doesn’t require user agents to support plugins at all. [NPAPI]
A plugin can be secured if it honors the semantics of the sandbox
attribute.
For example, a secured plugin would prevent its contents from creating pop-up windows when the
plugin is instantiated inside a sandboxed iframe
.
Browsers should take extreme care when interacting with external content intended for plugins. When third-party software is run with the same privileges as the user agent itself, vulnerabilities in the third-party software become as dangerous as if they were vulnerabilities of the user agent itself.
Since different users having different sets of plugins provides a fingerprinting vector
that increases the chances of users being uniquely identified, user agents are encouraged to
support the exact same set of plugins for each user.
2.1.6. Character encodings
A character encoding, or just encoding where that is not ambiguous, is a defined way to convert between byte streams and Unicode strings, as defined in the WHATWG Encoding specification. An encoding has an encoding name and one or more encoding labels, referred to as the encoding’s name and labels in the Encoding standard. [ENCODING]
A UTF-16 encoding is UTF-16BE or UTF-16LE. [ENCODING]
An ASCII-compatible encoding is any encoding that is not a UTF-16 encoding. [ENCODING]
Since support for encodings that are not defined in the WHATWG Encoding specification is prohibited, UTF-16 encodings are the only encodings that this specification needs to treat as not being ASCII-compatible encodings.
The term code unit is used as defined in the Web IDL specification: a 16 bit unsigned
integer, the smallest atomic component of a DOMString
. (This is a narrower definition
than the one used in Unicode, and is not the same as a code point.) [WEBIDL]
The term Unicode code point means a Unicode scalar value where possible, and an isolated surrogate code point when not. When a conformance requirement is defined in terms of characters or Unicode code points, a pair of code units consisting of a high surrogate followed by a low surrogate must be treated as the single code point represented by the surrogate pair, but isolated surrogates must each be treated as the single code point with the value of the surrogate. [UNICODE]
In this specification, the term character, when not qualified as Unicode character, is synonymous with the term Unicode code point.
The term Unicode character is used to mean a Unicode scalar value (i.e. any Unicode code point that is not a surrogate code point). [UNICODE]
The code-unit length of a string is the number of code units in that string.
This complexity results from the historical decision to define the DOM API in terms of 16 bit (UTF-16) code units, rather than in terms of Unicode characters.
2.2. Conformance requirements
All diagrams, examples, and notes in this specification are non-normative, as are all sections explicitly marked non-normative. Everything else in this specification is normative.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC2119. The key word "OPTIONALLY" in the normative parts of this document is to be interpreted with the same normative meaning as "MAY" and "OPTIONAL". For readability, these words do not appear in all uppercase letters in this specification. [RFC2119]
Requirements phrased in the imperative as part of algorithms (such as "strip any leading space characters" or "return false and abort these steps") are to be interpreted with the meaning of the key word ("must", "should", "may", etc) used in introducing the algorithm.
To eat an orange, the user must: 1. Peel the orange. 2. Separate each slice of the orange. 3. Eat the orange slices.
...it would be equivalent to the following:
To eat an orange: 1. The user must peel the orange. 2. The user must separate each slice of the orange. 3. The user must eat the orange slices.
Here the key word is "must".
The former (imperative) style is generally preferred in this specification for stylistic reasons.
Conformance requirements phrased as algorithms or specific steps may be implemented in any manner, so long as the end result is equivalent. (In particular, the algorithms defined in this specification are intended to be easy to follow, and not intended to be performant.)
2.2.1. Conformance classes
This specification describes the conformance criteria for user agents (relevant to implementors) and documents (relevant to authors and authoring tool implementors).
Conforming documents are those that comply with all the conformance criteria for documents. For readability, some of these conformance requirements are phrased as conformance requirements on authors; such requirements are implicitly requirements on documents: by definition, all documents are assumed to have had an author. (In some cases, that author may itself be a user agent — such user agents are subject to additional rules, as explained below.)
For example, if a requirement states that "authors must not use the foobar
element", it would imply that documents are not allowed to contain elements named foobar
.
There is no implied relationship between document conformance requirements and implementation conformance requirements. User agents are not free to handle non-conformant documents as they please; the processing model described in this specification applies to implementations regardless of the conformity of the input documents.
User agents fall into several (overlapping) categories with different conformance requirements.
-
Web browsers and other interactive user agents
-
Web browsers that support the XHTML syntax must process elements and attributes from the HTML namespace found in XML documents as described in this specification, so that users can interact with them, unless the semantics of those elements have been overridden by other specifications.
A conforming XHTML processor would, upon finding an XHTML
script
element in an XML document, execute the script contained in that element. However, if the element is found within a transformation expressed in XSLT (assuming the user agent also supports XSLT), then the processor would instead treat thescript
element as an opaque element that forms part of the transform.Web browsers that support the HTML syntax must process documents labeled with an HTML MIME type as described in this specification, so that users can interact with them.
User agents that support scripting must also be conforming implementations of the IDL fragments in this specification, as described in the Web IDL specification. [WEBIDL]
Unless explicitly stated, specifications that override the semantics of HTML elements do not override the requirements on DOM objects representing those elements. For example, the
script
element in the example above would still implement theHTMLScriptElement
interface. -
Non-interactive presentation user agents
-
User agents that process HTML and XHTML documents purely to render non-interactive versions of them must comply to the same conformance criteria as Web browsers, except that they are exempt from requirements regarding user interaction.
Typical examples of non-interactive presentation user agents are printers (static user agents) and overhead displays (dynamic user agents). It is expected that most static non-interactive presentation user agents will also opt to lack scripting support.
A non-interactive but dynamic presentation user agent would still execute scripts, allowing forms to be dynamically submitted, and so forth. However, since the concept of "focus" is irrelevant when the user cannot interact with the document, the user agent would not need to support any of the focus-related DOM APIs.
-
Visual user agents that support the suggested default rendering
-
User agents, whether interactive or not, may be designated (possibly as a user option) as supporting the suggested default rendering defined by this specification.
This is not required. In particular, even user agents that do implement the suggested default rendering are encouraged to offer settings that override this default to improve the experience for the user, e.g., changing the color contrast, using different focus styles, or otherwise making the experience more accessible and usable to the user.
User agents that are designated as supporting the suggested default rendering must, while so designated, implement the rules in §10 Rendering. That section defines the behavior that user agents are expected to implement.
-
User agents with no scripting support
-
Implementations that do not support scripting (or which have their scripting features disabled entirely) are exempt from supporting the events and DOM interfaces mentioned in this specification. For the parts of this specification that are defined in terms of an events model or in terms of the DOM, such user agents must still act as if events and the DOM were supported.
Scripting can form an integral part of an application. Web browsers that do not support scripting, or that have scripting disabled, might be unable to fully convey the author’s intent.
-
Conformance checkers
-
Conformance checkers must verify that a document conforms to the applicable conformance criteria described in this specification. Automated conformance checkers are exempt from detecting errors that require interpretation of the author’s intent (for example, while a document is non-conforming if the content of a
blockquote
element is not a quote, conformance checkers running without the input of human judgement do not have to check thatblockquote
elements only contain quoted material).Conformance checkers must check that the input document conforms when parsed without a browsing context (meaning that no scripts are run, and that the parser’s scripting flag is disabled), and should also check that the input document conforms when parsed with a browsing context in which scripts execute, and that the scripts never cause non-conforming states to occur other than transiently during script execution itself. (This is only a "SHOULD" and not a "MUST" requirement because it has been proven to be impossible. [COMPUTABLE])
The term "HTML validator" can be used to refer to a conformance checker that itself conforms to the applicable requirements of this specification.
XML DTDs cannot express all the conformance requirements of this specification. Therefore, a validating XML processor and a DTD cannot constitute a conformance checker. Also, since neither of the two authoring formats defined in this specification are applications of SGML, a validating SGML system cannot constitute a conformance checker either.To put it another way, there are three types of conformance criteria:
-
Criteria that can be expressed in a DTD.
-
Criteria that cannot be expressed by a DTD, but can still be checked by a machine.
-
Criteria that can only be checked by a human.
A conformance checker must check for the first two. A simple DTD-based validator only checks for the first class of errors and is therefore not a conforming conformance checker according to this specification.
-
-
Data mining tools
-
Applications and tools that process HTML and XHTML documents for reasons other than to either render the documents or check them for conformance should act in accordance with the semantics of the documents that they process.
A tool that generates document outlines but increases the nesting level for each paragraph and does not increase the nesting level for each section would not be conforming.
-
Authoring tools and markup generators
-
Authoring tools and markup generators must generate conforming documents. Conformance criteria that apply to authors also apply to authoring tools, where appropriate.
Authoring tools are exempt from the strict requirements of using elements only for their specified purpose, but only to the extent that authoring tools are not yet able to determine author intent. However, authoring tools must not automatically misuse elements or encourage their users to do so.
For example, it is not conforming to use an
address
element for arbitrary contact information; that element can only be used for marking up contact information for the author of the document or section. However, since an authoring tool is likely unable to determine the difference, an authoring tool is exempt from that requirement. This does not mean, though, that authoring tools can useaddress
elements for any block of italics text (for instance); it just means that the authoring tool doesn’t have to verify, if a user inserts contact information for a section or something else.In terms of conformance checking, an editor has to output documents that conform to the same extent that a conformance checker will verify.
When an authoring tool is used to edit a non-conforming document, it may preserve the conformance errors in sections of the document that were not edited during the editing session (i.e., an editing tool is allowed to round-trip erroneous content). However, an authoring tool must not claim that the output is conformant if errors have been so preserved.
Authoring tools are expected to come in two broad varieties: tools that work from structure or semantic data, and tools that work on a What-You-See-Is-What-You-Get media-specific editing basis (WYSIWYG).
The former is the preferred mechanism for tools that author HTML, since the structure in the source information can be used to make informed choices regarding which HTML elements and attributes are most appropriate.
However, WYSIWYG tools are legitimate. WYSIWYG tools should use elements they know are appropriate, and should not use elements that they do not know to be appropriate. This might in certain extreme cases mean limiting the use of flow elements to just a few elements, like
div
,b
,i
, andspan
and making liberal use of thestyle
attribute.All authoring tools, whether WYSIWYG or not, should make a best effort attempt at enabling users to create well-structured, semantically rich, media-independent content.
User agents may impose implementation-specific limits on otherwise unconstrained inputs, e.g., to
prevent denial of service attacks, to guard against running out of memory, or to work around
platform-specific limitations.
For compatibility with existing content and prior specifications, this specification describes two authoring formats: one based on XML (referred to as the XHTML syntax), and one using a custom format inspired by SGML (referred to as the HTML syntax). Implementations must support at least one of these two formats, although supporting both is encouraged.
Some conformance requirements are phrased as requirements on elements, attributes, methods or objects. Such requirements fall into two categories: those describing content model restrictions, and those describing implementation behavior. Those in the former category are requirements on documents and authoring tools. Those in the second category are requirements on user agents. Similarly, some conformance requirements are phrased as requirements on authors; such requirements are to be interpreted as conformance requirements on the documents that authors produce. (In other words, this specification does not distinguish between conformance criteria on authors and conformance criteria on documents.)
2.2.2. Dependencies
This specification relies on several other underlying specifications.
-
Unicode and Encoding
-
The Unicode character set is used to represent textual data, and the Encoding standard defines requirements around character encodings. [UNICODE]
This specification introduces terminology based on the terms defined in those specifications, as described earlier.
The following terms are used as defined in the Encoding standard: [ENCODING]
-
Getting an encoding
-
Get an output encoding
-
The generic decode algorithm which takes a byte stream and an encoding and returns a character stream
-
The UTF-8 decode algorithm which takes a byte stream and returns a character stream, additionally stripping one leading UTF-8 Byte Order Mark (BOM), if any
-
The UTF-8 decode without BOM algorithm which is identical to UTF-8 decode except that it does not strip one leading UTF-8 Byte Order Mark (BOM)
-
The UTF-8 decode without BOM or fail algorithm which is identical to UTF-8 decode without BOM except that it returns failure upon encountering an error
-
The encode algorithm which takes a character stream and an encoding and returns a byte stream
-
The UTF-8 encode algorithm which takes a character stream and returns a byte stream.
-
-
XML and related specifications
-
Implementations that support the XHTML syntax must support some version of XML, as well as its corresponding namespaces specification, because that syntax uses an XML serialization with namespaces. [XML] [XML-NAMES]
The attribute with the tag name
xml:space
in the XML namespace is defined by the XML specification. [XML]This specification also references the
<?xml-stylesheet?>
processing instruction, defined in the Associating Style Sheets with XML documents specification. [XML-STYLESHEET]This specification also non-normatively mentions the
XSLTProcessor
interface and itstransformToFragment()
andtransformToDocument()
methods. -
URLs
-
The following terms are defined in the WHATWG URL specification: [URL]
-
Origin of URLs
-
The URL parser and basic URL parser as well as these parser states:
-
URL record, as well as its individual components:
-
The URL serializer
-
The host parser
-
The host serializer
-
The domain to ASCII algorithm
-
The domain to Unicode algorithm
-
Parse errors from the URL parser
A number of schemes and protocols are referenced by this specification also:
-
HTTP and related specifications
-
The following terms are defined in the HTTP specifications: [HTTP]
-
Accept
header -
Accept-Language
header -
Cache-Control
header -
Content-Disposition
header -
Content-Language
header -
Content-Length
header -
Last-Modified
header -
Referer
header
The following terms are defined in the Cookie specification: [COOKIES]
-
cookie-string
The following term is defined in the Web Linking specification: [RFC5988]
-
-
Fetch
-
The following terms are defined in the WHATWG Fetch specification: [FETCH]
-
the
RequestCredentials
enumeration -
response and its associated:
-
request and its associated:
-
Web IDL
-
The IDL fragments in this specification must be interpreted as required for conforming IDL fragments, as described in the Web IDL specification. [WEBIDL]
The following terms are defined in the Web IDL specification:
-
Global environment associated with a platform object
-
Read only (when applied to arrays)
-
Converting between WebIDL types and JS types
The Web IDL specification also defines the following types that are used in Web IDL fragments in this specification:
The term throw in this specification is used as defined in the WebIDL specification. The following exception names are defined by WebIDL and used by this specification:
When this specification requires a user agent to create a
Date
object representing a particular time (which could be the special value Not-a-Number), the milliseconds component of that time, if any, must be truncated to an integer, and the time value of the newly createdDate
object must represent the resulting truncated time.For instance, given the time 23045 millionths of a second after 01:00 UTC on January 1st 2000, i.e., the time 2000-01-01T00:00:00.023045Z, then the
Date
object created representing that time would represent the same time as that created representing the time 2000-01-01T00:00:00.023Z, 45 millionths earlier. If the given time is NaN, then the result is aDate
object that represents a time value NaN (indicating that the object does not represent a specific instant of time). -
JavaScript
-
Some parts of the language described by this specification only support JavaScript as the underlying scripting language. [ECMA-262]
The term "JavaScript" is used to refer to ECMA262, rather than the official term ECMAScript, since the term JavaScript is more widely known. Similarly, the MIME type used to refer to JavaScript in this specification is
text/javascript
, since that is the most commonly used type, despite it being an officially obsoleted type according to RFC 4329. [RFC4329]The following terms are defined in the JavaScript specification and used in this specification [ECMA-262]:
-
Well-Known Symbols, including:
-
@@hasInstance
-
@@isConcatSpreadable
-
@@toPrimitive
-
@@toStringTag
-
-
Well-Known Intrinsic Objects, including:
-
The FunctionBody production
-
The Pattern production
-
The Script production
-
The Type notation
-
The Property Descriptor specification type
-
The ArrayCreate abstract operation
-
The Call abstract operation
-
The CloneArrayBuffer abstract operation
-
The Construct abstract operation
-
The CreateDataProperty abstract operation
-
The DetachArrayBuffer abstract operation
-
The EnqueueJob abstract operation
-
The FunctionCreate abstract operation
-
The Get abstract operation
-
The GetActiveScriptOrModule abstract operation
-
The GetFunctionRealm abstract operation
-
The HasOwnProperty abstract operation
-
The HostEnsureCanCompileStrings abstract operation
-
The HostPromiseRejectionTracker abstract operation
-
The InitializeHostDefinedRealm abstract operation
-
The IsAccessorDescriptor abstract operation
-
The IsCallable abstract operation
-
The IsConstructor abstract operation
-
The IsDataDescriptor abstract operation
-
The IsDetachedBuffer abstract operation
-
The NewObjectEnvironment abstract operation
-
The OrdinaryGetPrototypeOf abstract operation
-
The OrdinarySetPrototypeOf abstract operation
-
The OrdinaryIsExtensible abstract operation
-
The OrdinaryPreventExtensions abstract operation
-
The OrdinaryGetOwnProperty abstract operation
-
The OrdinaryDefineOwnProperty abstract operation
-
The OrdinaryGet abstract operation
-
The OrdinarySet abstract operation
-
The OrdinaryDelete abstract operation
-
The OrdinaryOwnPropertyKeys abstract operation
-
The ParseScript abstract operation
-
The RunJobs abstract operation
-
The SameValue abstract operation
-
The ScriptEvaluation abstract operation
-
The ToBoolean abstract operation
-
The ToString abstract operation
-
The ToUint32 abstract operation
-
The TypedArrayCreate abstract operation
-
The Abstract Equality Comparison algorithm
-
The Strict Equality Comparison algorithm
-
The
ArrayBuffer
object -
The
Date
object -
The
SyntaxError
object -
The
TypeError
object -
The
RangeError
object -
The
RegExp
object -
The typeof operator
-
DOM
-
The Document Object Model (DOM) is a representation — a model — of a document and its content. The DOM is not just an API; the conformance criteria of HTML implementations are defined, in this specification, in terms of operations on the DOM. [DOM]
Implementations must support DOM and the events defined in UI Events, because this specification is defined in terms of the DOM, and some of the features are defined as extensions to the DOM interfaces. [DOM] [UIEVENTS]
In particular, the following features are defined in the DOM specification: [DOM]
-
Attr
interface -
Comment
interface -
DOMImplementation
interface -
Document
interface -
XMLDocument
interface -
DocumentFragment
interface -
DocumentType
interface -
DOMException
interface -
ChildNode
interface -
Element
interface -
Node
interface -
NodeList
interface -
ProcessingInstruction
interface -
Text
interface -
HTMLCollection
interface -
item()
method -
The terms collections and represented by the collection
-
DOMTokenList
interface -
createDocument()
method -
createHTMLDocument()
method -
createElement()
method -
createElementNS()
method -
getElementById()
method -
getElementsByClassName()
method -
insertBefore()
method -
appendChild()
method -
cloneNode()
method -
importNode()
method -
childNodes
attribute -
localName
attribute -
parentNode
attribute -
namespaceURI
attribute -
tagName
attribute -
id
attribute -
textContent
attribute -
The insert, append, remove, replace, and adopt algorithms for nodes
-
The insertion steps, removing steps, and adopting steps hooks
-
The attribute list concept.
-
The data of a text node.
-
Event
interface -
EventTarget
interface -
EventInit
dictionary type -
target
attribute -
currentTarget
attribute -
isTrusted
attribute -
initEvent()
method -
addEventListener()
method -
The
type
of an event -
The concept of an event listener and the event listeners associated with an
EventTarget
-
The concept of a regular event parent and a cross-boundary event parent
-
The encoding (herein the character encoding) and content type of a
Document
-
The distinction between XML documents and HTML documents
-
The terms quirks mode, limited-quirks mode, and no-quirks mode
-
The algorithm to clone a
Node
, and the concept of cloning steps used by that algorithm -
The concept of base URL change steps and the definition of what happens when an element is affected by a base URL change
-
The concept of an element’s unique identifier (ID)
-
The term supported tokens
-
The concept of a DOM range, and the terms start, end, and boundary point as applied to ranges.
-
MutationObserver
interface and mutation observers in general
The term throw in this specification is used as defined in the DOM specification. The following DOMException types are defined in the DOM specification: [DOM]
For example, to throw a
TimeoutError
exception, a user agent would construct a DOMException object whose type was the string "TimeoutError
" (and whose code was the number 23, for legacy reasons) and actually throw that object as an exception.The following features are defined in the UI Events specification: [UIEVENTS]
-
MouseEvent
interface and the following interface members:-
The
relatedTarget
attribute -
The
button
attribute -
The
ctrlKey
attribute -
The
shiftKey
attribute -
The
altKey
attribute -
The
metaKey
attribute -
The
getModifierState()
method
-
-
MouseEventInit
dictionary type -
The
FocusEvent
interface and itsrelatedTarget
attribute -
click event
-
dblclick event
-
mousedown event
-
mouseenter event
-
mouseleave event
-
mousemove event
-
mouseout event
-
mouseover event
-
mouseup event
-
wheel event
-
keydown event
-
keyup event
-
keypress event
The following features are defined in the Touch Events specification: [TOUCH-EVENTS]
-
Touch
interface -
Touch point concept
This specification sometimes uses the term name to refer to the event’s
type
; as in, "an event namedclick
" or "if the event name iskeypress
". The terms "name" and "type" for events are synonymous.The following features are defined in the DOM Parsing and Serialization specification: [DOM-Parsing]
The
Selection
interface is defined in the Selection API specification. [SELECTION-API]User agents are also encouraged to implement the features described in the HTML Editing APIs and
UndoManager
and DOM Transaction specifications. [EDITING] [UNDO]The following parts of the Fullscreen specification are referenced from this specification, in part to define how the Fullscreen API interacts with the sandboxing features in HTML: [FULLSCREEN]
-
The top layer concept
-
The fully exit fullscreen algorithm
The High Resolution Time specification provides the
DOMHighResTimeStamp
typedef and thePerformance
object’snow()
method. [HR-TIME-2] -
-
File API
-
This specification uses the following features defined in the File API specification: [FILEAPI]
-
Media Source Extensions
-
The following terms are defined in the Media Source Extensions specification: [MEDIA-SOURCE]
-
Detaching from a media element
-
-
Media Capture and Streams
-
The following term is defined in the Media Capture and Streams specification: [MEDIACAPTURE-STREAMS]
-
XMLHttpRequest
-
This specification references the XMLHttpRequest specification to describe how the two specifications interact. The following features and terms are defined in the XMLHttpRequest specification: [XHR]
-
XMLHttpRequest
interface -
XMLHttpRequest.responseXML
attribute
-
-
This specification references the Progress Events specification to describe how the two specifications interact and to use its
ProgressEvent
feature. The following feature are defined in the Progress Events specification: [PROGRESS-EVENTS]-
ProgressEvent
interface -
ProgressEvent.lengthComputable
attribute -
ProgressEvent.loaded
attribute -
ProgressEvent.total
attribute
-
-
Server-Sent Events
-
This specification references
EventSource
which is specified in the Server-Sent Events specification [EVENTSOURCE] -
Media Queries
-
Implementations must support the Media Queries language. [MEDIAQ]
-
CSS modules
-
While support for CSS as a whole is not required of implementations of this specification (though it is encouraged, at least for Web browsers), some features are defined in terms of specific CSS requirements.
In particular, some features require that a string be parsed as a CSS <color> value. When parsing a CSS value, user agents are required by the CSS specifications to apply some error handling rules. These apply to this specification also. [CSS3COLOR] [CSS-2015]
For example, user agents are required to close all open constructs upon finding the end of a style sheet unexpectedly. Thus, when parsing the string "
rgb(0,0,0
" (with a missing close-parenthesis) for a color value, the close parenthesis is implied by this error handling rule, and a value is obtained (the color black). However, the similar construct "rgb(0,0,
" (with both a missing parenthesis and a missing "blue" value) cannot be parsed, as closing the open construct does not result in a viable value.The following terms and features are defined in the CSS specification: [CSS-2015]
-
viewport
-
replaced element
-
intrinsic dimensions
The term named color is defined in the CSS Color specification. [CSS3COLOR]
The terms intrinsic width and intrinsic height refer to the width dimension and the height dimension, respectively, of intrinsic dimensions.
The term provides a paint source is used as defined in the CSS Image Values and Replaced Content specification to define the interaction of certain HTML elements with the CSS 'element()' function. [CSS3-IMAGES]
The term default object size is also defined in the CSS Image Values and Replaced Content specification. [CSS3-IMAGES]
Implementations that support scripting must support the CSS Object Model. The following features and terms are defined in the CSSOM specifications: [CSSOM] [CSSOM-VIEW]
-
cssText
attribute ofCSSStyleDeclaration
-
CSS style sheets and their properties: type, location, parent CSS style sheet, owner node, owner CSS rule, media, title, alternate flag, disabled flag, CSS rules, origin-clean flag
-
Alternative style sheet sets and the preferred style sheet set
-
The
resize
event -
The
scroll
event
The following features and terms are defined in the CSS Syntax specifications: [CSS-SYNTAX-3]
The feature <length> is defined in the CSS Values and Units specification. [CSS-VALUES]
The term CSS styling attribute is defined in the CSS Style Attributes specification. [CSS-STYLE-ATTR]
The
CanvasRenderingContext2D
object’s use of fonts depends on the features described in the CSS Fonts and Font Loading specifications, including in particularFontFace
objects and the font source concept. [CSS-FONTS-3] [CSS-FONT-LOADING-3]The following interface is defined in the Geometry Interfaces Module specification: [GEOMETRY-1]
-
DOMMatrix
interface
-
-
SVG
-
The
CanvasRenderingContext2D
object’s use of fonts depends on the features described in the CSS Fonts and Font Loading specifications, including in particularFontFace
objects and the font source concept. [CSS-FONTS-3] [CSS-FONT-LOADING-3]The following interface is defined in the SVG specification: [SVG11]
-
WebGL
-
The following interface is defined in the WebGL specification: [WEBGL]
-
WebVTT
-
Implementations may support WebVTT as a text track format for subtitles, captions, chapter titles, metadata, etc, for media resources. [WEBVTT]
The following terms, used in this specification, are defined in the WebVTT specification:
-
The WebSocket protocol
-
The following terms are defined in the WebSocket protocol specification: [RFC6455]
-
ARIA
-
The
role
attribute is defined in the ARIA specification, as are the following roles: [WAI-ARIA]In addition, the following
aria-*
content attributes are defined in the ARIA specification: [WAI-ARIA] -
Content Security Policy
-
The following terms are defined in Content Security Policy: [CSP3]
-
The parse a serialized Content Security Policy algorithm
-
The Initialize a global object’s CSP list algorithm
-
The Initialize a Document’s CSP list algorithm
-
The Should element’s inline behavior be blocked by Content Security Policy? algorithm
-
The
report-uri
,frame-ancestors
, andsandbox
directives -
The EnsureCSPDoesNotBlockStringCompilation abstract algorithm
-
The Is base allowed for Document? algorithm
The following terms are defined in Content Security Policy: Document Features
-
Service Workers
-
The following terms are defined in Service Workers: [SERVICE-WORKERS]
-
match service worker registration
-
This specification does not require support of any particular network protocol, style sheet language, scripting language, or any of the DOM specifications beyond those required in the list above. However, the language described by this specification is biased towards CSS as the styling language, JavaScript as the scripting language, and HTTP as the network protocol, and several features assume that those languages and protocols are in use.
A user agent that implements the HTTP protocol must implement the Web Origin Concept specification and the HTTP State Management Mechanism specification (Cookies) as well. [HTTP] [ORIGIN] [COOKIES]
This specification might have certain additional requirements on character encodings, image formats, audio formats, and video formats in the respective sections.
2.2.3. Extensibility
Vendor-specific proprietary user agent extensions to this specification are strongly discouraged. Documents must not use such extensions, as doing so reduces interoperability and fragments the user base, allowing only users of specific user agents to access the content in question.
If such extensions are nonetheless needed, e.g., for experimental purposes, then vendors are strongly urged to use one of the following extension mechanisms:
-
For markup-level features that can be limited to the XML serialization and need not be supported in the HTML serialization, vendors should use the namespace mechanism to define custom namespaces in which the non-standard elements and attributes are supported.
-
For markup-level features that are intended for use with the HTML syntax, extensions should be limited to new attributes of the form "
x-vendor-feature
", where vendor is a short string that identifies the vendor responsible for the extension, and feature is the name of the feature. New element names should not be created. Using attributes for such extensions exclusively allows extensions from multiple vendors to co-exist on the same element, which would not be possible with elements. Using the "x-vendor-feature
" form allows extensions to be made without risk of conflicting with future additions to the specification.For instance, a browser named "FerretBrowser" could use "ferret" as a vendor prefix, while a browser named "Mellblom Browser" could use "mb". If both of these browsers invented extensions that turned elements into scratch-and-sniff areas, an author experimenting with these features could write:<p>This smells of lemons! <span x-ferret-smellovision x-ferret-smellcode="LEM01" x-mb-outputsmell x-mb-smell="lemon juice"></span></p>
Attribute names beginning with the two characters "x-
" are reserved for
user agent use and are guaranteed to never be formally added to the HTML language. For
flexibility, attributes names containing underscores (the U+005F LOW LINE character) are also
reserved for experimental purposes and are guaranteed to never be formally added to the HTML
language.
Pages that use such attributes are by definition non-conforming.
For DOM extensions, e.g., new methods and IDL attributes, the new members should be prefixed by vendor-specific strings to prevent clashes with future versions of this specification.
For events, experimental event types should be prefixed with vendor-specific strings.
pleasold
" and
thus name the event "pleasoldgoingup
", possibly with an event handler attribute
named "onpleasoldgoingup
". All extensions must be defined so that the use of extensions neither contradicts nor causes the non-conformance of functionality defined in the specification.
fooTypeTime
" to a control’s DOM interface that returned
the time it took the user to select the current value of a control (say). On the other hand,
defining a new control that appears in a form’s elements
array would be in
violation of the above requirement, as it would violate the definition of elements
given in this specification. When adding new reflecting IDL attributes corresponding to content attributes of the form
"x-vendor-feature
", the IDL attribute should be named
"vendorFeature
" (i.e., the "x
" is dropped from
the IDL attribute’s name).
When vendor-neutral extensions to this specification are needed, either this specification can be updated accordingly, or an extension specification can be written that overrides the requirements in this specification. When someone applying this specification to their activities decides that they will recognize the requirements of such an extension specification, it becomes an applicable specification for the purposes of conformance requirements in this specification.
Someone could write a specification that defines any arbitrary byte stream as conforming, and then claim that their random junk is conforming. However, that does not mean that their random junk actually is conforming for everyone’s purposes: if someone else decides that the specification does not apply to their work, then they can quite legitimately say that the aforementioned random junk is just that, junk, and not conforming at all. As far as conformance goes, what matters in a particular community is what that community agrees is applicable.
applicable specification.
The conformance terminology for documents depends on the nature of the changes introduced by such applicable specifications, and on the content and intended interpretation of the document. Applicable specifications MAY define new document content (e.g., a foobar element), MAY prohibit certain otherwise conforming content (e.g., prohibit use of <table>s), or MAY change the semantics, DOM mappings, or other processing rules for content defined in this specification. Whether a document is or is not a conforming HTML document does not depend on the use of applicable specifications: if the syntax and semantics of a given conforming HTML document is unchanged by the use of applicable specification(s), then that document remains a conforming HTML document. If the semantics or processing of a given (otherwise conforming) document is changed by use of applicable specification(s), then it is not a conforming HTML document. For such cases, the applicable specifications SHOULD define conformance terminology.
As a suggested but not required convention, such specifications might define conformance terminology such as: "Conforming HTML+XXX document", where XXX is a short name for the applicable specification. (Example: "Conforming HTML+AutomotiveExtensions document").
a consequence of the rule given above is that certain syntactically correct HTML documents may not be conforming HTML documents in the presence of applicable specifications. (Example: the applicable specification defines <table> to be a piece of furniture — a document written to that specification and containing a <table> element is NOT a conforming HTML document, even if the element happens to be syntactically correct HTML.)
User agents must treat elements and attributes that they do not understand as semantically neutral; leaving them in the DOM (for DOM processors), and styling them according to CSS (for CSS processors), but not inferring any meaning from them.
When support for a feature is disabled (e.g., as an emergency measure to mitigate a security problem, or to aid in development, or for performance reasons), user agents must act as if they had no support for the feature whatsoever, and as if the feature was not mentioned in this specification. For example, if a particular feature is accessed via an attribute in a Web IDL interface, the attribute itself would be omitted from the objects that implement that interface — leaving the attribute on the object but making it return null or throw an exception is insufficient.
2.2.4. Interactions with XPath and XSLT
Implementations of XPath 1.0 that operate on HTML documents parsed or created in the
manners described in this specification (e.g., as part of the document.evaluate()
API)
must act as if the following edit was applied to the XPath 1.0 specification.
First, remove this paragraph:
A QName in the node test is expanded into an expanded-name using the namespace
declarations from the expression context. This is the same way expansion is done for element
type names in start and end-tags except that the default namespace declared with xmlns
is not used: if the QName does not have a prefix, then the namespace
URI is null (this is the same way attribute names are expanded). It is an error if the QName has a prefix for which there is no namespace declaration in the expression context.
Then, insert in its place the following:
A QName in the node test is expanded into an expanded-name using the namespace declarations from the expression context. If the QName has a prefix, then there must be a namespace declaration for this prefix in the expression context, and the corresponding namespace URI is the one that is associated with this prefix. It is an error if the QName has a prefix for which there is no namespace declaration in the expression context.If the QName has no prefix and the principal node type of the axis is element, then the default element namespace is used. Otherwise if the QName has no prefix, the namespace URI is null. The default element namespace is a member of the context for the XPath expression. The value of the default element namespace when executing an XPath expression through the DOM3 XPath API is determined in the following way:
If the context node is from an HTML DOM, the default element namespace is "https://www.w3.org/1999/xhtml".
Otherwise, the default element namespace URI is null.
This is equivalent to adding the default element namespace feature of XPath 2.0 to XPath 1.0, and using the HTML namespace as the default element namespace for HTML documents. It is motivated by the desire to have implementations be compatible with legacy HTML content while still supporting the changes that this specification introduces to HTML regarding the namespace used for HTML elements, and by the desire to use XPath 1.0 rather than XPath 2.0.
This change is a willful violation of the XPath 1.0 specification, motivated by desire to have implementations be compatible with legacy content while still supporting the changes that this specification introduces to HTML regarding which namespace is used for HTML elements. [XPATH]
XSLT 1.0 processors outputting to a DOM when the output method is "html" (either explicitly or via the defaulting rule in XSLT 1.0) are affected as follows:
If the transformation program outputs an element in no namespace, the processor must, prior to constructing the corresponding DOM element node, change the namespace of the element to the HTML namespace, ASCII-lowercase the element’s local name, and ASCII-lowercase the names of any non-namespaced attributes on the element.
This requirement is a willful violation of the XSLT 1.0 specification, required because this specification changes the namespaces and case-sensitivity rules of HTML in a manner that would otherwise be incompatible with DOM-based XSLT transformations. (Processors that serialize the output are unaffected.) [XSLT]
This specification does not specify precisely how XSLT processing interacts with the HTML parser infrastructure (for example, whether an XSLT processor acts as if it puts any
elements into a stack of open elements). However, XSLT processors must stop parsing if they successfully complete, and must set the current document readiness first to
"interactive
" and then to "complete
" if they are aborted.
This specification does not specify how XSLT interacts with the navigation algorithm, how it fits in with the event loop, nor how error pages are to be handled (e.g., whether XSLT errors are to replace an incremental XSLT output, or are rendered inline, etc).
There are also additional non-normative comments regarding the interaction of XSLT and HTML in the script
element section,
and of XSLT, XPath, and HTML in the template
element section.
2.3. Case-sensitivity and string comparison
Comparing two strings in a case-sensitive manner means comparing them exactly, code point for code point.
Comparing two strings in an ASCII case-insensitive manner means comparing them exactly, code point for code point, except that the characters in the range U+0041 to U+005A (i.e., LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and the corresponding characters in the range U+0061 to U+007A (i.e., LATIN SMALL LETTER A to LATIN SMALL LETTER Z) are considered to also match.
Comparing two strings in a compatibility caseless manner means using the Unicode compatibility caseless match operation to compare the two strings, with no language-specific tailorings. [UNICODE]
Except where otherwise stated, string comparisons must be performed in a case-sensitive manner.
Converting a string to ASCII uppercase means replacing all characters in the range U+0061 to U+007A (i.e., LATIN SMALL LETTER A to LATIN SMALL LETTER Z) with the corresponding characters in the range U+0041 to U+005A (i.e., LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z).
Converting a string to ASCII lowercase means replacing all characters in the range U+0041 to U+005A (i.e., LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) with the corresponding characters in the range U+0061 to U+007A (i.e., LATIN SMALL LETTER A to LATIN SMALL LETTER Z).
A string pattern is a prefix match for a string s when pattern is not longer than s and truncating s to pattern’s length leaves the two strings as matches of each other.
2.4. Common microsyntaxes
There are various places in HTML that accept particular data types, such as dates or numbers. This section describes what the conformance criteria for content in those formats is, and how to parse them.
Implementors are strongly urged to carefully examine any third-party libraries they might consider using to implement the parsing of syntaxes described below. For example, date libraries are likely to implement error handling behavior that differs from what is required in this specification, since error-handling behavior is often not defined in specifications that describe date syntaxes similar to those used in this specification, and thus implementations tend to vary greatly in how they handle errors.
2.4.1. Common parser idioms
The space characters, for the purposes of this specification, are U+0020 SPACE, U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED (LF), U+000C FORM FEED (FF), and U+000D CARRIAGE RETURN (CR).
The White_Space characters are those that have the Unicode property "White_Space" in
the Unicode PropList.txt
data file. [UNICODE]
This should not be confused with the "White_Space" value (abbreviated "WS") of the "Bidi_Class"
property in the Unicode.txt
data file.
The control characters are those whose Unicode "General_Category" property has the
value "Cc" in the Unicode UnicodeData.txt
data file. [UNICODE]
The uppercase ASCII letters are the characters in the range U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z.
The lowercase ASCII letters are the characters in the range U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER Z.
The ASCII digits are the characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).
The alphanumeric ASCII characters are those that are either uppercase ASCII letters, lowercase ASCII letters, or ASCII digits.
The ASCII hex digits are the characters in the ranges U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F, and U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F.
The uppercase ASCII hex digits are the characters in the ranges U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) and U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F only.
The lowercase ASCII hex digits are the characters in the ranges U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) and U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F only.
Some of the micro-parsers described below follow the pattern of having an input variable that holds the string being parsed, and having a position variable pointing at the next character to parse in input.
For parsers based on this pattern, a step that requires the user agent to collect a sequence of characters means that the following algorithm must be run, with characters being the set of characters that can be collected:
-
Let input and position be the same variables as those of the same name in the algorithm that invoked these steps.
-
Let result be the empty string.
-
While position doesn’t point past the end of input and the character at position is one of the characters, append that character to the end of result and advance position to the next character in input.
-
Return result.
The step skip whitespace means that the user agent must collect a sequence of characters that are space characters. The collected characters are not used.
When a user agent is to strip line breaks from a string, the user agent must remove any U+000A LINE FEED (LF) and U+000D CARRIAGE RETURN (CR) characters from that string.
When a user agent is to strip leading and trailing whitespace from a string, the user agent must remove all space characters that are at the start or end of the string.
When a user agent is to strip and collapse whitespace in a string, it must replace any sequence of one or more consecutive space characters in that string with a single U+0020 SPACE character, and then strip leading and trailing whitespace from that string.
When a user agent has to strictly split a string on a particular delimiter character delimiter, it must use the following algorithm:
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Let tokens be an ordered list of tokens, initially empty.
-
While position is not past the end of input:
-
Collect a sequence of characters that are not the delimiter character.
-
Append the string collected in the previous step to tokens.
-
Advance position to the next character in input.
-
-
Return tokens.
For the special cases of splitting a string on spaces and on commas, this algorithm does not apply (those algorithms also perform whitespace trimming).
2.4.2. Boolean attributes
A number of attributes are boolean attributes. The presence of a boolean attribute on an element represents the true value, and the absence of the attribute represents the false value.
If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute’s canonical name, with no leading or trailing whitespace.
The values "true" and "false" are not allowed on boolean attributes. To represent a false value, the attribute has to be omitted altogether.
checked
and disabled
attributes are the boolean attributes.
<label><input type=checkbox checked name=cheese disabled> Cheese</label>
This could be equivalently written as this:
<label><input type=checkbox checked=checked name=cheese disabled=disabled> Cheese</label>
You can also mix styles; the following is still equivalent:
<label><input type='checkbox' checked name=cheese disabled=""> Cheese</label>
2.4.3. Keywords and enumerated attributes
Some attributes are defined as taking one of a finite set of keywords. Such attributes are called enumerated attributes. The keywords are each defined to map to a particular state (several keywords might map to the same state, in which case some of the keywords are synonyms of each other; additionally, some of the keywords can be said to be non-conforming, and are only in the specification for historical reasons). In addition, two default states can be given. The first is the invalid value default, the second is the missing value default.
If an enumerated attribute is specified, the attribute’s value must be an ASCII case-insensitive match for one of the given keywords that are not said to be non-conforming, with no leading or trailing whitespace.
When the attribute is specified, if its value is an ASCII case-insensitive match for one of the given keywords then that keyword’s state is the state that the attribute represents. If the attribute value matches none of the given keywords, but the attribute has an invalid value default, then the attribute represents that state. Otherwise, if the attribute value matches none of the keywords but there is a missing value default state defined, then that is the state represented by the attribute. Otherwise, there is no default, and invalid values mean that there is no state represented.
When the attribute is not specified, if there is a missing value default state defined, then that is the state represented by the (missing) attribute. Otherwise, the absence of the attribute means that there is no state represented.
The empty string can be a valid keyword.
2.4.4. Numbers
2.4.4.1. Signed integers
A string is a valid integer if it consists of one or more ASCII digits, optionally prefixed with a U+002D HYPHEN-MINUS character (-).
A valid integer without a U+002D HYPHEN-MINUS (-) prefix represents the number that is represented in base ten by that string of digits. A valid integer with a U+002D HYPHEN-MINUS (-) prefix represents the number represented in base ten by the string of digits that follows the U+002D HYPHEN-MINUS, subtracted from zero.
The rules for parsing integers are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either an integer or an error.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Let sign have the value "positive".
-
If position is past the end of input, return an error.
-
If the character indicated by position (the first character) is a U+002D HYPHEN-MINUS character (-):
-
Let sign be "negative".
-
Advance position to the next character.
-
If position is past the end of input, return an error.
Otherwise, if the character indicated by position (the first character) is a U+002B PLUS SIGN character (+):
-
Advance position to the next character. (The "
+
" is ignored, but it is not conforming.) -
If position is past the end of input, return an error.
-
-
If the character indicated by position is not an ASCII digit, then return an error.
-
Collect a sequence of characters that are ASCII digits, and interpret the resulting sequence as a base-ten integer. Let value be that integer.
-
If sign is "positive", return value, otherwise return the result of subtracting value from zero.
2.4.4.2. Non-negative integers
A string is a valid non-negative integer if it consists of one or more ASCII digits.
A valid non-negative integer represents the number that is represented in base ten by that string of digits.
The rules for parsing non-negative integers are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either zero, a positive integer, or an error.
-
Let input be the string being parsed.
-
Let value be the result of parsing input using the rules for parsing integers.
-
If value is an error, return an error.
-
If value is less than zero, return an error.
-
Return value.
2.4.4.3. Floating-point numbers
A string is a valid floating-point number if it consists of:
-
Optionally, a U+002D HYPHEN-MINUS character (-).
-
One or both of the following, in the given order:
-
A series of one or more ASCII digits.
-
Both of the following, in the given order:
-
A single U+002E FULL STOP character (.).
-
A series of one or more ASCII digits.
-
-
-
Optionally:
-
Either a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN CAPITAL LETTER E character (E).
-
Optionally, a U+002D HYPHEN-MINUS character (-) or U+002B PLUS SIGN character (+).
-
A series of one or more ASCII digits.
-
A valid floating-point number represents the number obtained by multiplying the significand by ten raised to the power of the exponent, where the significand is the first number, interpreted as base ten (including the decimal point and the number after the decimal point, if any, and interpreting the significand as a negative number if the whole string starts with a U+002D HYPHEN-MINUS character (-) and the number is not zero), and where the exponent is the number after the E, if any (interpreted as a negative number if there is a U+002D HYPHEN-MINUS character (-) between the E and the number and the number is not zero, or else ignoring a U+002B PLUS SIGN character (+) between the E and the number if there is one). If there is no E, then the exponent is treated as zero.
The Infinity and Not-a-Number (NaN) values are not valid floating-point numbers.
The best representation of the number n as a floating-point number is the string obtained from running ToString(n). The abstract operation ToString is not uniquely determined. When there are multiple possible strings that could be obtained from ToString for a particular value, the user agent must always return the same string for that value (though it may differ from the value used by other user agents).
The rules for parsing floating-point number values are as given in the following algorithm. This algorithm must be aborted at the first step that returns something. This algorithm will return either a number or an error.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Let value have the value 1.
-
Let divisor have the value 1.
-
Let exponent have the value 1.
-
If position is past the end of input, return an error.
-
If the character indicated by position is a U+002D HYPHEN-MINUS character (-):
-
Change value and divisor to -1.
-
Advance position to the next character.
-
If position is past the end of input, return an error.
Otherwise, if the character indicated by position (the first character) is a U+002B PLUS SIGN character (+):
-
Advance position to the next character. (The "
+
" is ignored, but it is not conforming.) -
If position is past the end of input, return an error.
-
-
If the character indicated by position is a U+002E FULL STOP (.), and that is not the last character in input, and the character after the character indicated by position is an ASCII digit, then set value to zero and jump to the step labeled fraction.
-
If the character indicated by position is not an ASCII digit, then return an error.
-
Collect a sequence of characters that are ASCII digits, and interpret the resulting sequence as a base-ten integer. Multiply value by that integer.
-
If position is past the end of input, jump to the step labeled conversion.
-
Fraction: If the character indicated by position is a U+002E FULL STOP (.), run these substeps:
-
Advance position to the next character.
-
If position is past the end of input, or if the character indicated by position is not an ASCII digit, U+0065 LATIN SMALL LETTER E (e), or U+0045 LATIN CAPITAL LETTER E (E), then jump to the step labeled conversion.
-
If the character indicated by position is a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN CAPITAL LETTER E character (E), skip the remainder of these substeps.
-
Fraction loop: Multiply divisor by ten.
-
Add the value of the character indicated by position, interpreted as a base-ten digit (0..9) and divided by divisor, to value.
-
Advance position to the next character.
-
If position is past the end of input, then jump to the step labeled conversion.
-
If the character indicated by position is an ASCII digit, jump back to the step labeled fraction loop in these substeps.
-
-
If the character indicated by position is a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN CAPITAL LETTER E character (E), run these substeps:
-
Advance position to the next character.
-
If position is past the end of input, then jump to the step labeled conversion.
-
If the character indicated by position is a U+002D HYPHEN-MINUS character (-):
-
Change exponent to -1.
-
Advance position to the next character.
-
If position is past the end of input, then jump to the step labeled conversion.
Otherwise, if the character indicated by position is a U+002B PLUS SIGN character (+):
-
Advance position to the next character.
-
If position is past the end of input, then jump to the step labeled conversion.
-
-
If the character indicated by position is not an ASCII digit, then jump to the step labeled conversion.
-
Collect a sequence of characters that are ASCII digits, and interpret the resulting sequence as a base-ten integer. Multiply exponent by that integer.
-
Multiply value by ten raised to the exponentth power.
-
-
Conversion: Let S be the set of finite IEEE 754 double-precision floating-point values except -0, but with two special values added: 21024 and -21024.
-
Let rounded-value be the number in S that is closest to value, selecting the number with an even significand if there are two equally close values. (The two special values 21024 and -21024 are considered to have even significands for this purpose.)
-
If rounded-value is 21024 or -21024, return an error.
-
Return rounded-value.
2.4.4.4. Percentages and lengths
The rules for parsing dimension values are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either a number greater than or equal to 0.0, or an error; if a number is returned, then it is further categorized as either a percentage or a length.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
If position is past the end of input, return an error.
-
If the character indicated by position is a U+002B PLUS SIGN character (+), advance position to the next character.
-
If position is past the end of input, return an error.
-
If the character indicated by position is not an ASCII digit, then return an error.
-
Collect a sequence of characters that are ASCII digits, and interpret the resulting sequence as a base-ten integer. Let value be that number.
-
If position is past the end of input, return value as a length.
-
If the character indicated by position is a U+002E FULL STOP character (.):
-
Advance position to the next character.
-
If position is past the end of input, or if the character indicated by position is not an ASCII digit, then return value as a length.
-
Let divisor have the value 1.
-
Fraction loop: Multiply divisor by ten.
-
Add the value of the character indicated by position, interpreted as a base-ten digit (0..9) and divided by divisor, to value.
-
Advance position to the next character.
-
If position is past the end of input, then return value as a length.
-
If the character indicated by position is an ASCII digit, return to the step labeled fraction loop in these substeps.
-
-
If position is past the end of input, return value as a length.
-
If the character indicated by position is a U+0025 PERCENT SIGN character (%), return value as a percentage.
-
Return value as a length.
2.4.4.5. Non-zero percentages and lengths
The rules for parsing non-zero dimension values are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either a number greater than 0.0, or an error; if a number is returned, then it is further categorized as either a percentage or a length.
-
Let input be the string being parsed.
-
Let value be the result of parsing input using the rules for parsing dimension values.
-
If value is an error, return an error.
-
If value is zero, return an error.
-
If value is a percentage, return value as a percentage.
-
Return value as a length.
2.4.4.6. Lists of floating-point numbers
A valid list of floating-point numbers is a number of valid floating-point numbers separated by U+002C COMMA characters, with no other characters (e.g. no space characters). In addition, there might be restrictions on the number of floating-point numbers that can be given, or on the range of values allowed.
The rules for parsing a list of floating-point numbers are as follows:
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Let numbers be an initially empty list of floating-point numbers. This list will be the result of this algorithm.
-
Collect a sequence of characters that are space characters, U+002C COMMA, or U+003B SEMICOLON characters. This skips past any leading delimiters.
-
While position is not past the end of input:
-
Collect a sequence of characters that are not space characters, U+002C COMMA, U+003B SEMICOLON, ASCII digits, U+002E FULL STOP, or U+002D HYPHEN-MINUS characters. This skips past leading garbage.
-
Collect a sequence of characters that are not space characters, U+002C COMMA, or U+003B SEMICOLON characters, and let unparsed number be the result.
-
Let number be the result of parsing unparsed number using the rules for parsing floating-point number values.
-
If number is an error, set number to zero.
-
Append number to numbers.
-
Collect a sequence of characters that are space characters, U+002C COMMA, or U+003B SEMICOLON characters. This skips past the delimiter.
-
-
Return numbers.
2.4.4.7. Lists of dimensions
The rules for parsing a list of dimensions are as follows. These rules return a list of zero or more pairs consisting of a number and a unit, the unit being one of percentage, relative, and absolute.
-
Let raw input be the string being parsed.
-
If the last character in raw input is a U+002C COMMA character (,), then remove that character from raw input.
-
Split the string raw input on commas. Let raw tokens be the resulting list of tokens.
-
Let result be an empty list of number/unit pairs.
-
For each token in raw tokens, run the following substeps:
-
Let input be the token.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Let value be the number 0.
-
Let unit be absolute.
-
If position is past the end of input, set unit to relative and jump to the last substep.
-
If the character at position is an ASCII digit, collect a sequence of characters that are ASCII digits, interpret the resulting sequence as an integer in base ten, and increment value by that integer.
-
If the character at position is a U+002E FULL STOP character (.), run these substeps:
-
Collect a sequence of characters consisting of space characters and ASCII digits. Let s be the resulting sequence.
-
Remove all space characters in s.
-
If s is not the empty string, run these subsubsteps:
-
Let length be the number of characters in s (after the spaces were removed).
-
Let fraction be the result of interpreting s as a base-ten integer, and then dividing that number by 10length.
-
Increment value by fraction.
-
-
-
If the character at position is a U+0025 PERCENT SIGN character (%), then set unit to percentage.
Otherwise, if the character at position is a U+002A ASTERISK character (*), then set unit to relative.
-
Add an entry to result consisting of the number given by value and the unit given by unit.
-
-
Return the list result.
2.4.5. Dates and times
This means that encoded dates will look like 1582-03-01, 0033-03-27, or 2016-03-01, and date-times will look like 1929-11-13T19:00Z, 0325-06-03T00:21+10:30. The format is approximately YYYY-MM-DDTHH:MM:SS.DD±HH:MM, although some parts are optional, for example to express a month and day as in a birthday, a time without time-zone information, and the like.
Times are expressed using the 24-hour clock, and it is as error to express leap seconds.
Dates are expressed in the proleptic Gregorian calendar between the proleptic year 0000, and the year
-
Other years cannot be encoded.
The proleptic Gregorian calendar is the calendar most common globally since around 1950, and is likely to be understood by almost everyone for dates between the years 1950 and 9999, and for many people for dates in the last few decades or centuries.
The Gregorian calendar was adopted officially in different countries at different times, between the years 1582 when it was proposed by Pope Gregory XIII as a replacement for the Julian calendar, and 1949 when it was adopted by the People’s republic of China.
For most practical purposes, dealing with the present, recent past, or the next few thousand years, this will work without problems. For dates before the adoption of the Gregorian Calendar - for example prior to 1917 in Russia or Turkey, prior to 1752 in Britain or the then British colonies of America, or prior to 1582 in Spain, the Spanish colonies in America, and the rest of the world, dates will not match those written at the time.
The use of the Gregorian calendar as an underlying encoding is a somewhat arbitrary choice. Many other calendars were or are in use, and the interested reader should look for information on the Web.
See also the discussion of date, time, and number formats in forms (for authors), implementation
notes regarding localization of form controls, and the time
element.
In the algorithms below, the number of days in month month of year year is: 31 if month is 1, 3, 5, 7, 8, 10, or 12; 30 if month is 4, 6, 9, or 11; 29 if month is 2 and year is a number divisible by 400, or if year is a number divisible by 4 but not by 100; and 28 otherwise. This takes into account leap years in the Gregorian calendar. [GREGORIAN]
When ASCII digits are used in the date and time syntaxes defined in this section, they express numbers in base ten.
While the formats described here are intended to be subsets of the corresponding ISO8601 formats, this specification defines parsing rules in much more detail than ISO8601. Implementors are therefore encouraged to carefully examine any date parsing libraries before using them to implement the parsing rules described below; ISO8601 libraries might not parse dates and times in exactly the same manner. [ISO8601]
Where this specification refers to the proleptic Gregorian calendar, it means the modern Gregorian calendar, extrapolated backwards to year 1. A date in the proleptic Gregorian calendar, sometimes explicitly referred to as a proleptic-Gregorian date, is one that is described using that calendar even if that calendar was not in use at the time (or place) in question. [GREGORIAN]
2.4.5.1. Months
A month consists of a specific proleptic-Gregorian date with no time-zone information and no date information beyond a year and a month. [GREGORIAN]
A string is a valid month string representing a year year and month month if it consists of the following components in the given order:
-
Four or more ASCII digits, representing year, where year > 0
-
A U+002D HYPHEN-MINUS character (-)
-
Two ASCII digits, representing the month month, in the range 1 ≤ month ≤ 12
For example, February 2005 is encoded 2005-02, and March of the year 33AD (as a proleptic
gregorian date) is encoded 0033-03
. The expression 325-03
does not mean March in the year 325, it is an error, because it does not have 4 digits for
the year.
The rules to parse a month string are as follows. This will return either a year and month, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Parse a month component to obtain year and month. If this returns nothing, then fail.
-
If position is not beyond the end of input, then fail.
-
Return year and month.
The rules to parse a month component, given an input string and a position, are as follows. This will return either a year and a month, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Collect a sequence of characters that are ASCII digits. If the collected sequence is not at least four characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the year.
-
If year is not a number greater than zero, then fail.
-
If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail. Otherwise, move position forwards one character.
-
Collect a sequence of characters that are ASCII digits. If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the month.
-
If month is not a number in the range 1 ≤ month ≤ 12, then fail.
-
Return year and month.
2.4.5.2. Dates
A date consists of a specific proleptic-Gregorian date with no time-zone information, consisting of a year, a month, and a day. [GREGORIAN]
A string is a valid date string representing a year year, month month, and day day if it consists of the following components in the given order:
-
A valid month string, representing year and month
-
A U+002D HYPHEN-MINUS character (-)
-
Two ASCII digits, representing day, in the range 1 ≤ day ≤ maxday where maxday is the number of days in the month month and year year
For example, 29 February 2016 is encoded 2016-02-29, and 3 March of the year 33AD (as a
proleptic gregorian date) is encoded 0033-03-03
. The expression 325-03-03
does not mean 3 March in the year 325, it is an error, because
it does not have 4 digits for the year.
The rules to parse a date string are as follows. This will return either a date, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
-
If position is not beyond the end of input, then fail.
-
Let date be the date with year year, month month, and day day.
-
Return date.
The rules to parse a date component, given an input string and a position, are as follows. This will return either a year, a month, and a day, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Parse a month component to obtain year and month. If this returns nothing, then fail.
-
Let maxday be the number of days in month month of year year.
-
If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail. Otherwise, move position forwards one character.
-
Collect a sequence of characters that are ASCII digits. If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the day.
-
If day is not a number in the range 1 ≤ day ≤ maxday, then fail.
-
Return year, month, and day.
2.4.5.3. Yearless dates
A yearless date consists of a Gregorian month and a day within that month, but with no associated year. [GREGORIAN]
A string is a valid yearless date string representing a month month and a day day if it consists of the following components in the given order:
-
Optionally, two U+002D HYPHEN-MINUS characters (-)
-
Two ASCII digits, representing the month month, in the range 1 ≤ month ≤ 12
-
A U+002D HYPHEN-MINUS character (-)
-
Two ASCII digits, representing day, in the range 1 ≤ day ≤ maxday where maxday is the number of days in the month month and any arbitrary leap year (e.g., 4 or 2000)
In other words, if the month is "02
", meaning February, then the day can
be 29, as if the year was a leap year.
For example, 29 February is encoded 02-29
, and 3 March is encoded 03-03
.
The rules to parse a yearless date string are as follows. This will return either a month and a day, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Parse a yearless date component to obtain month and day. If this returns nothing, then fail.
-
If position is not beyond the end of input, then fail.
-
Return month and day.
The rules to parse a yearless date component, given an input string and a position, are as follows. This will return either a month and a day, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Collect a sequence of characters that are U+002D HYPHEN-MINUS characters (-). If the collected sequence is not exactly zero or two characters long, then fail.
-
Collect a sequence of characters that are ASCII digits. If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the month.
-
If month is not a number in the range 1 ≤ month ≤ 12, then fail.
-
Let maxday be the number of days in month month of any arbitrary leap year (e.g., 4 or 2000).
-
If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail. Otherwise, move position forwards one character.
-
Collect a sequence of characters that are ASCII digits. If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the day.
-
If day is not a number in the range 1 ≤ day ≤ maxday, then fail.
-
Return month and day.
2.4.5.4. Times
A time consists of a specific time with no time-zone information, consisting of an hour, a minute, a second, and a fraction of a second.
A string is a valid time string representing an hour hour, a minute minute, and a second second if it consists of the following components in the given order:
-
Two ASCII digits, representing hour, in the range 0 ≤ hour ≤ 23
-
A U+003A COLON character (:)
-
Two ASCII digits, representing minute, in the range 0 ≤ minute ≤ 59
-
If second is non-zero, or optionally if second is zero:
-
A U+003A COLON character (:)
-
Two ASCII digits, representing the integer part of second, in the range 0 ≤ s ≤ 59
-
If second is not an integer, or optionally if second is an integer:
-
A 002E FULL STOP character (.)
-
One, two, or three ASCII digits, representing the fractional part of second
-
-
The second component cannot be 60 or 61; leap seconds cannot be represented.
Times are encoded using the 24 hour clock, with optional seconds, and optional decimal fractions
of seconds. Thus 7.45pm is encoded as 19:45
. Note that parsing that time will return
19:45:00, or 7.45pm and zero seconds. 19:45:45.456
is 456 thousandths of
a second after 7.45pm and 45 seconds.
The rules to parse a time string are as follows. This will return either a time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
-
If position is not beyond the end of input, then fail.
-
Let time be the time with hour hour, minute minute, and second second.
-
Return time.
The rules to parse a time component, given an input string and a position, are as follows. This will return either an hour, a minute, and a second, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Collect a sequence of characters that are ASCII digits. If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the hour.
-
If hour is not a number in the range 0 ≤ hour ≤ 23, then fail.
-
If position is beyond the end of input or if the character at position is not a U+003A COLON character, then fail. Otherwise, move position forwards one character.
-
Collect a sequence of characters that are ASCII digits. If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the minute.
-
If minute is not a number in the range 0 ≤ minute ≤ 59, then fail.
-
Let second be a string with the value "0".
-
If position is not beyond the end of input and the character at position is a U+003A COLON, then run these substeps:
-
Advance position to the next character in input.
-
If position is beyond the end of input, or at the last character in input, or if the next two characters in input starting at position are not both ASCII digits, then fail.
-
Collect a sequence of characters that are either ASCII digits or U+002E FULL STOP characters. If the collected sequence is three characters long, or if it is longer than three characters long and the third character is not a U+002E FULL STOP character, or if it has more than one U+002E FULL STOP character, then fail. Otherwise, let second be the collected string.
-
-
Interpret second as a base-ten number (possibly with a fractional part). Let second be that number instead of the string version.
-
If second is not a number in the range 0 ≤ second < 60, then fail.
-
Return hour, minute, and second.
2.4.5.5. Floating dates and times
A floating date and time consists of a specific proleptic-Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, but expressed without a time zone. [GREGORIAN]
A string is a valid floating date and time string representing a date and time if it consists of the following components in the given order:
-
A valid date string representing the date
-
A U+0054 LATIN CAPITAL LETTER T character (T) or a U+0020 SPACE character
-
A valid time string representing the time
A string is a valid normalized floating date and time string representing a date and time if it consists of the following components in the given order:
-
A valid date string representing the date
-
A U+0054 LATIN CAPITAL LETTER T character (T)
-
A valid time string representing the time, expressed as the shortest possible string for the given time (e.g., omitting the seconds component entirely if the given time is zero seconds past the minute)
The rules to parse a floating date and time string are as follows. This will return either a date and time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
-
If position is beyond the end of input or if the character at position is neither a U+0054 LATIN CAPITAL LETTER T character (T) nor a U+0020 SPACE character, then fail. Otherwise, move position forwards one character.
-
Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
-
If position is not beyond the end of input, then fail.
-
Let date be the date with year year, month month, and day day.
-
Let time be the time with hour hour, minute minute, and second second.
-
Return date and time.
2.4.5.6. Time zones
A time-zone offset consists of a signed number of hours and minutes.
A string is a valid time-zone offset string representing a time-zone offset if it consists of either:
-
A U+005A LATIN CAPITAL LETTER Z character (Z), allowed only if the time zone is UTC
-
Or, the following components, in the given order:
-
Either a U+002B PLUS SIGN character (+) or, if the time-zone offset is not zero, a U+002D HYPHEN-MINUS character (-), representing the sign of the time-zone offset
-
Two ASCII digits, representing the hours component hour of the time-zone offset, in the range 0 ≤ hour ≤ 23
-
Optionally, a U+003A COLON character (:)
-
Two ASCII digits, representing the minutes component minute of the time-zone offset, in the range 0 ≤ minute ≤ 59
-
This format allows for time-zone offsets from -23:59 to +23:59. In practice, however, right now the range of offsets of actual time zones is -12:00 to +14:00, and the minutes component of offsets of actual time zones is always either 00, 30, or 45. There is no guarantee that this will remain so forever, however; time zones are changed by countries at will and do not follow a standard.
See also the usage notes and examples in the global date and time section below for details on using time-zone offsets with historical times that predate the formation of formal time zones.
The rules to parse a time-zone offset string are as follows. This will return either a time-zone offset, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Parse a time-zone offset component to obtain timezonehours and timezoneminutes. If this returns nothing, then fail.
-
If position is not beyond the end of input, then fail.
-
Return the time-zone offset that is timezonehours hours and timezoneminutes minutes from UTC.
The rules to parse a time-zone offset component, given an input string and a position, are as follows. This will return either time-zone hours and time-zone minutes, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
If the character at position is a U+005A LATIN CAPITAL LETTER Z character (Z), then:
-
Let timezonehours be 0.
-
Let timezoneminutes be 0.
-
Advance position to the next character in input.
Otherwise, if the character at position is either a U+002B PLUS SIGN (+) or a U+002D HYPHEN-MINUS (-), then:
-
If the character at position is a U+002B PLUS SIGN (+), let sign be "positive". Otherwise, it’s a U+002D HYPHEN-MINUS (-); let sign be "negative".
-
Advance position to the next character in input.
-
Collect a sequence of characters that are ASCII digits. Let s be the collected sequence.
-
If s is exactly two characters long, then run these substeps:
-
Interpret s as a base-ten integer. Let that number be the timezonehours.
-
If position is beyond the end of input or if the character at position is not a U+003A COLON character, then fail. Otherwise, move position forwards one character.
-
Collect a sequence of characters that are ASCII digits. If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the timezoneminutes.
If s is exactly four characters long, then run these substeps:
-
Interpret the first two characters of s as a base-ten integer. Let that number be the timezonehours.
-
Interpret the last two characters of s as a base-ten integer. Let that number be the timezoneminutes.
Otherwise, fail.
-
-
If timezonehours is not a number in the range 0 ≤ timezonehours ≤ 23, then fail.
-
If sign is "negative", then negate timezonehours.
-
If timezoneminutes is not a number in the range 0 ≤ timezoneminutes ≤ 59, then fail.
-
If sign is "negative", then negate timezoneminutes.
Otherwise, fail.
-
-
Return timezonehours and timezoneminutes.
2.4.5.7. Global dates and times
A global date and time consists of a specific proleptic-Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, expressed with a time-zone offset, consisting of a signed number of hours and minutes. [GREGORIAN]
A string is a valid global date and time string representing a date, time, and a time-zone offset if it consists of the following components in the given order:
-
A valid date string representing the date
-
A U+0054 LATIN CAPITAL LETTER T character (T) or a U+0020 SPACE character
-
A valid time string representing the time
-
A valid time-zone offset string representing the time-zone offset
Times in dates before the formation of UTC in the mid twentieth century must be expressed and interpreted in terms of UT1 (contemporary Earth mean solar time at the 0° longitude), not UTC (the approximation of UT1 that ticks in SI seconds). Time before the formation of time zones must be expressed and interpreted as UT1 times with explicit time zones that approximate the contemporary difference between the appropriate local time and the time observed at the location of Greenwich, London.
-
"
0037-12-13 00:00Z
" -
Midnight in areas using London time on the birthday of Nero (the Roman Emperor). See below for further discussion on which date this actually corresponds to.
-
"
1979-10-14T12:00:00.001-04:00
" -
One millisecond after noon on October 14th 1979, in the time zone in use on the east coast of the USA during daylight saving time.
-
"
8592-01-01T02:09+02:09
" -
Midnight UTC on the 1st of January, 8592. The time zone associated with that time is two hours and nine minutes ahead of UTC, which is not currently a real time zone, but is nonetheless allowed.
Several things are notable about these dates:
-
Years with fewer than four digits have to be zero-padded. The date "37-12-13" would not be a valid date.
-
If the "
T
" is replaced by a space, it must be a single space character. The string "2001-12-21 12:00Z
" (with two spaces between the components) would not be parsed successfully. -
To unambiguously identify a moment in time prior to the introduction of the Gregorian calendar (insofar as moments in time before the formation of UTC can be unambiguously identified), the date has to be first converted to the Gregorian calendar from the calendar in use at the time (e.g., from the Julian calendar). The date of Nero’s birth is the 15th of December 37, in the Julian Calendar, which is the 13th of December 37 in the proleptic Gregorian calendar.
-
The time and time-zone offset components are not optional.
-
Dates before the year one can’t be represented as a datetime in this version of HTML.
-
Times of specific events in ancient times are, at best, approximations, since time was not well coordinated or measured until relatively recent decades.
-
Time-zone offsets differ based on daylight savings time.
The zone offset is not a complete time zone specification. When working with real date and time values, consider using a separate field for time zone, perhaps using IANA time zone IDs. [TIMEZONE]
A string is a valid normalized global date and time string representing a date, time, and a time-zone offset if it consists of the following components in the given order:
-
A valid date string representing the date converted to the UTC time zone
-
A U+0054 LATIN CAPITAL LETTER T character (T)
-
A valid time string representing the time converted to the UTC time zone and expressed as the shortest possible string for the given time (e.g., omitting the seconds component entirely if the given time is zero seconds past the minute)
-
A U+005A LATIN CAPITAL LETTER Z character (Z)
The rules to parse a global date and time string are as follows. This will return either a time in UTC, with associated time-zone offset information for round-tripping or display purposes, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
-
If position is beyond the end of input or if the character at position is neither a U+0054 LATIN CAPITAL LETTER T character (T) nor a U+0020 SPACE character, then fail. Otherwise, move position forwards one character.
-
Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
-
If position is beyond the end of input, then fail.
-
Parse a time-zone offset component to obtain timezonehours and timezoneminutes. If this returns nothing, then fail.
-
If position is not beyond the end of input, then fail.
-
Let time be the moment in time at year year, month month, day day, hours hour, minute minute, second second, subtracting timezonehours hours and timezoneminutes minutes. That moment in time is a moment in the UTC time zone.
-
Let timezone be timezonehours hours and timezoneminutes minutes from UTC.
-
Return time and timezone.
2.4.5.8. Weeks
A week consists of a week-year number and a week number representing a seven-day period starting on a Monday. Each week-year in this calendaring system has either 52 or 53 such seven-day periods, as defined below. The seven-day period starting on the Gregorian date Monday December 29th 1969 (1969-12-29) is defined as week number 1 in week-year 1970. Consecutive weeks are numbered sequentially. The week before the number 1 week in a week-year is the last week in the previous week-year, and vice versa. [GREGORIAN]
A week-year with a number year has 53 weeks if it corresponds to either a year year in the proleptic Gregorian calendar that has a Thursday as its first day (January 1st), or a year year in the proleptic Gregorian calendar that has a Wednesday as its first day (January 1st) and where year is a number divisible by 400, or a number divisible by 4 but not by 100. All other week-years have 52 weeks.
The week number of the last day of a week-year with 53 weeks is 53; the week number of the last day of a week-year with 52 weeks is 52.
The week-year number of a particular day can be different than the number of the year that contains that day in the proleptic Gregorian calendar. The first week in a week-year y is the week that contains the first Thursday of the Gregorian year y.
For modern purposes, a week as defined here is equivalent to ISO weeks as defined in ISO 8601. [ISO8601]
A string is a valid week string representing a week-year year and week week if it consists of the following components in the given order:
-
Four or more ASCII digits, representing year, where year > 0
-
A U+002D HYPHEN-MINUS character (-)
-
A U+0057 LATIN CAPITAL LETTER W character (W)
-
Two ASCII digits, representing the week week, in the range 1 ≤ week ≤ maxweek, where maxweek is the week number of the last day of week-year year
The rules to parse a week string are as follows. This will return either a week-year number and week number, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Collect a sequence of characters that are ASCII digits. If the collected sequence is not at least four characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the year.
-
If year is not a number greater than zero, then fail.
-
If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail. Otherwise, move position forwards one character.
-
If position is beyond the end of input or if the character at position is not a U+0057 LATIN CAPITAL LETTER W character (W), then fail. Otherwise, move position forwards one character.
-
Collect a sequence of characters that are ASCII digits. If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the week.
-
Let maxweek be the week number of the last day of year year.
-
If week is not a number in the range 1 ≤ week ≤ maxweek, then fail.
-
If position is not beyond the end of input, then fail.
-
Return the week-year number year and the week number week.
2.4.5.9. Durations
A duration consists of a number of seconds.
Since months and seconds are not comparable (a month is not a precise number of seconds, but is instead a period whose exact length depends on the precise day from which it is measured) a duration as defined in this specification cannot include months (or years, which are equivalent to twelve months). Only durations that describe a specific number of seconds can be described.
A string is a valid duration string representing a duration t if it consists of either of the following:
-
A literal U+0050 LATIN CAPITAL LETTER P character followed by one or more of the following subcomponents, in the order given, where the number of days, hours, minutes, and seconds corresponds to the same number of seconds as in t:
-
One or more ASCII digits followed by a U+0044 LATIN CAPITAL LETTER D character, representing a number of days.
-
A U+0054 LATIN CAPITAL LETTER T character followed by one or more of the following subcomponents, in the order given:
-
One or more ASCII digits followed by a U+0048 LATIN CAPITAL LETTER H character, representing a number of hours.
-
One or more ASCII digits followed by a U+004D LATIN CAPITAL LETTER M character, representing a number of minutes.
-
The following components:
-
One or more ASCII digits, representing a number of seconds.
-
Optionally, a U+002E FULL STOP character (.) followed by one, two, or three ASCII digits, representing a fraction of a second.
-
A U+0053 LATIN CAPITAL LETTER S character.
-
-
This, as with a number of other date- and time-related microsyntaxes defined in this specification, is based on one of the formats defined in ISO 8601. [ISO8601]
-
-
One or more duration time components, each with a different duration time component scale, in any order; the sum of the represented seconds being equal to the number of seconds in t.
A duration time component is a string consisting of the following components:
-
Zero or more space characters.
-
One or more ASCII digits, representing a number of time units, scaled by the duration time component scale specified (see below) to represent a number of seconds.
-
If the duration time component scale specified is 1 (i.e., the units are seconds), then, optionally, a U+002E FULL STOP character (.) followed by one, two, or three ASCII digits, representing a fraction of a second.
-
Zero or more space characters.
-
One of the following characters, representing the duration time component scale of the time unit used in the numeric part of the duration time component:
-
U+0057 LATIN CAPITAL LETTER W character
U+0077 LATIN SMALL LETTER W character
-
Weeks. The scale is 604800.
-
U+0044 LATIN CAPITAL LETTER D character
U+0064 LATIN SMALL LETTER D character
-
Days. The scale is 86400.
-
U+0048 LATIN CAPITAL LETTER H character
U+0068 LATIN SMALL LETTER H character
-
Hours. The scale is 3600.
-
U+004D LATIN CAPITAL LETTER M character
U+006D LATIN SMALL LETTER M character
-
Minutes. The scale is 60.
-
U+0053 LATIN CAPITAL LETTER S character
U+0073 LATIN SMALL LETTER S character
-
Seconds. The scale is 1.
-
-
Zero or more space characters.
This is not based on any of the formats in ISO 8601. It is intended to be a more human-readable alternative to the ISO 8601 duration format.
-
The rules to parse a duration string are as follows. This will return either a duration or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Let months, seconds, and component count all be zero.
-
Let M-disambiguator be minutes.
This flag’s other value is months. It is used to disambiguate the "M" unit in ISO8601 durations, which use the same unit for months and minutes. Months are not allowed, but are parsed for future compatibility and to avoid misinterpreting ISO8601 durations that would be valid in other contexts.
-
If position is past the end of input, then fail.
-
If the character in input pointed to by position is a U+0050 LATIN CAPITAL LETTER P character, then advance position to the next character, set M-disambiguator to months, and skip whitespace.
-
Run the following substeps in a loop, until a step requiring the loop to be broken or the entire algorithm to fail is reached:
-
Let units be undefined. It will be assigned one of the following values: years, months, weeks, days, hours, minutes, and seconds.
-
Let next character be undefined. It is used to process characters from the input.
-
If position is past the end of input, then break the loop.
-
If the character in input pointed to by position is a U+0054 LATIN CAPITAL LETTER T character, then advance position to the next character, set M-disambiguator to minutes, skip whitespace, and return to the top of the loop.
-
Set next character to the character in input pointed to by position.
-
If next character is a U+002E FULL STOP character (.), then let N equal zero. (Do not advance position. That is taken care of below.)
Otherwise, if next character is an ASCII digit, then collect a sequence of characters that are ASCII digits, interpret the resulting sequence as a base-ten integer, and let N be that number.
Otherwise next character is not part of a number; fail.
-
If position is past the end of input, then fail.
-
Set next character to the character in input pointed to by position, and this time advance position to the next character. (If next character was a U+002E FULL STOP character (.) before, it will still be that character this time.)
-
If next character is a U+002E FULL STOP character (.), then run these substeps:
-
Collect a sequence of characters that are ASCII digits. Let s be the resulting sequence.
-
If s is the empty string, then fail.
-
Let length be the number of characters in s.
-
Let fraction be the result of interpreting s as a base-ten integer, and then dividing that number by 10length.
-
Increment N by fraction.
-
If position is past the end of input, then fail.
-
Set next character to the character in input pointed to by position, and advance position to the next character.
-
If next character is neither a U+0053 LATIN CAPITAL LETTER S character nor a U+0073 LATIN SMALL LETTER S character, then fail.
-
Set units to seconds.
Otherwise, run these substeps:
-
If next character is a space character, then skip whitespace, set next character to the character in input pointed to by position, and advance position to the next character.
-
If next character is a U+0059 LATIN CAPITAL LETTER Y character, or a U+0079 LATIN SMALL LETTER Y character, set units to years and set M-disambiguator to months.
If next character is a U+004D LATIN CAPITAL LETTER M character or a U+006D LATIN SMALL LETTER M character, and M-disambiguator is months, then set units to months.
If next character is a U+0057 LATIN CAPITAL LETTER W character or a U+0077 LATIN SMALL LETTER W character, set units to weeks and set M-disambiguator to minutes.
If next character is a U+0044 LATIN CAPITAL LETTER D character or a U+0064 LATIN SMALL LETTER D character, set units to days and set M-disambiguator to minutes.
If next character is a U+0048 LATIN CAPITAL LETTER H character or a U+0068 LATIN SMALL LETTER H character, set units to hours and set M-disambiguator to minutes.
If next character is a U+004D LATIN CAPITAL LETTER M character or a U+006D LATIN SMALL LETTER M character, and M-disambiguator is minutes, then set units to minutes.
If next character is a U+0053 LATIN CAPITAL LETTER S character or a U+0073 LATIN SMALL LETTER S character, set units to seconds and set M-disambiguator to minutes.
Otherwise if next character is none of the above characters, then fail.
-
-
Increment component count.
-
Let multiplier be 1.
-
If units is years, multiply multiplier by 12 and set units to months.
-
If units is months, add the product of N and multiplier to months.
Otherwise, run these substeps:
-
If units is weeks, multiply multiplier by 7 and set units to days.
-
If units is days, multiply multiplier by 24 and set units to hours.
-
If units is hours, multiply multiplier by 60 and set units to minutes.
-
If units is minutes, multiply multiplier by 60 and set units to seconds.
-
Forcibly, units is now seconds. Add the product of N and multiplier to seconds.
-
-
-
If component count is zero, fail.
-
If months is not zero, fail.
-
Return the duration consisting of seconds seconds.
2.4.5.10. Vaguer moments in time
A string is a valid date string with optional time if it is also one of the following:
The rules to parse a date or time string are as follows. The algorithm will return either a date, a time, a global date and time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Set start position to the same position as position.
-
Set the date present and time present flags to true.
-
Parse a date component to obtain year, month, and day. If this fails, then set the date present flag to false.
-
If date present is true, and position is not beyond the end of input, and the character at position is either a U+0054 LATIN CAPITAL LETTER T character (T) or a U+0020 SPACE character, then advance position to the next character in input.
Otherwise, if date present is true, and either position is beyond the end of input or the character at position is neither a U+0054 LATIN CAPITAL LETTER T character (T) nor a U+0020 SPACE character, then set time present to false.
Otherwise, if date present is false, set position back to the same position as start position.
-
If the time present flag is true, then parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
-
If the date present and time present flags are both true, but position is beyond the end of input, then fail.
-
If the date present and time present flags are both true, parse a time-zone offset component to obtain timezonehours and timezoneminutes. If this returns nothing, then fail.
-
If position is not beyond the end of input, then fail.
-
If the date present flag is true and the time present flag is false, then let date be the date with year year, month month, and day day, and return date.
Otherwise, if the time present flag is true and the date present flag is false, then let time be the time with hour hour, minute minute, and second second, and return time.
Otherwise, let time be the moment in time at year year, month month, day day, hours hour, minute minute, second second, subtracting timezonehours hours and timezoneminutes minutes, that moment in time being a moment in the UTC time zone; let timezone be timezonehours hours and timezoneminutes minutes from UTC; and return time and timezone.
2.4.6. Colors
A simple color consists of three 8-bit numbers in the range 0..255, representing the red, green, and blue components of the color respectively, in the sRGB color space. [SRGB]
A string is a valid simple color if it is exactly seven characters long, and the first character is a U+0023 NUMBER SIGN character (#), and the remaining six characters are all ASCII hex digits, with the first two digits representing the red component, the middle two digits representing the green component, and the last two digits representing the blue component, in hexadecimal.
A string is a valid lowercase simple color if it is a valid simple color and doesn’t use any characters in the range U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F.
The rules for parsing simple color values are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either a simple color or an error.
-
Let input be the string being parsed.
-
If input is not exactly seven characters long, then return an error.
-
If the first character in input is not a U+0023 NUMBER SIGN character (#), then return an error.
-
If the last six characters of input are not all ASCII hex digits, then return an error.
-
Let result be a simple color.
-
Interpret the second and third characters as a hexadecimal number and let the result be the red component of result.
-
Interpret the fourth and fifth characters as a hexadecimal number and let the result be the green component of result.
-
Interpret the sixth and seventh characters as a hexadecimal number and let the result be the blue component of result.
-
Return result.
The rules for serializing simple color values given a simple color are as given in the following algorithm:
-
Let result be a string consisting of a single U+0023 NUMBER SIGN character (#).
-
Convert the red, green, and blue components in turn to two-digit hexadecimal numbers using lowercase ASCII hex digits, zero-padding if necessary, and append these numbers to result, in the order red, green, blue.
-
Return result, which will be a valid lowercase simple color.
Some obsolete legacy attributes parse colors in a more complicated manner, using the rules for parsing a legacy color value, which are given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either a simple color or an error.
-
Let input be the string being parsed.
-
If input is the empty string, then return an error.
-
Strip leading and trailing whitespace from input.
-
If input is an ASCII case-insensitive match for the string "
transparent
", then return an error. -
If input is an ASCII case-insensitive match for one of the named colors, then return the simple color corresponding to that keyword. [CSS3COLOR]
CSS2 System Colors are not recognized.
-
If input is four characters long, and the first character in input is a U+0023 NUMBER SIGN character (#), and the last three characters of input are all ASCII hex digits, then run these substeps:
-
Let result be a simple color.
-
Interpret the second character of input as a hexadecimal digit; let the red component of result be the resulting number multiplied by 17.
-
Interpret the third character of input as a hexadecimal digit; let the green component of result be the resulting number multiplied by 17.
-
Interpret the fourth character of input as a hexadecimal digit; let the blue component of result be the resulting number multiplied by 17.
-
Return result.
-
-
Replace any characters in input that have a Unicode code point greater than U+FFFF (i.e., any characters that are not in the basic multilingual plane) with the two-character string "
00
". -
If input is longer than 128 characters, truncate input, leaving only the first 128 characters.
-
If the first character in input is a U+0023 NUMBER SIGN character (#), remove it.
-
Replace any character in input that is not an ASCII hex digit with the character U+0030 DIGIT ZERO (0).
-
While input’s length is zero or not a multiple of three, append a U+0030 DIGIT ZERO (0) character to input.
-
Split input into three strings of equal length, to obtain three components. Let length be the length of those components (one third the length of input).
-
If length is greater than 8, then remove the leading length-8 characters in each component, and let length be 8.
-
While length is greater than two and the first character in each component is a U+0030 DIGIT ZERO (0) character, remove that character and reduce length by one.
-
If length is still greater than two, truncate each component, leaving only the first two characters in each.
-
Let result be a simple color.
-
Interpret the first component as a hexadecimal number; let the red component of result be the resulting number.
-
Interpret the second component as a hexadecimal number; let the green component of result be the resulting number.
-
Interpret the third component as a hexadecimal number; let the blue component of result be the resulting number.
-
Return result.
2.4.7. Space-separated tokens
A set of space-separated tokens is a string containing zero or more words (known as tokens) separated by one or more space characters, where words consist of any string of one or more characters, none of which are space characters.
A string containing a set of space-separated tokens may have leading or trailing space characters.
An unordered set of unique space-separated tokens is a set of space-separated tokens where none of the tokens are duplicated.
An ordered set of unique space-separated tokens is a set of space-separated tokens where none of the tokens are duplicated but where the order of the tokens is meaningful.
Sets of space-separated tokens sometimes have a defined set of allowed values. When a set of allowed values is defined, the tokens must all be from that list of allowed values; other values are non-conforming. If no such set of allowed values is provided, then all values are conforming.
How tokens in a set of space-separated tokens are to be compared (e.g., case-sensitively or not) is defined on a per-set basis.
When a user agent has to split a string on spaces, it must use the following algorithm:
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Let tokens be an ordered list of tokens, initially empty.
-
While position is not past the end of input:
-
Collect a sequence of characters that are not space characters.
-
Append the string collected in the previous step to tokens.
-
-
Return tokens.
2.4.8. Comma-separated tokens
A set of comma-separated tokens is a string containing zero or more tokens each separated from the next by a single U+002C COMMA character (,), where tokens consist of any string of zero or more characters, neither beginning nor ending with space characters, nor containing any U+002C COMMA characters (,), and optionally surrounded by space characters.
For instance, the string " a ,b,d d
" consists of four tokens:
"a", "b", the empty string, and "d d". Leading and trailing whitespace around each token
doesn’t count as part of the token, and the empty string can be a token.
Sets of comma-separated tokens sometimes have further restrictions on what consists a valid token. When such restrictions are defined, the tokens must all fit within those restrictions; other values are non-conforming. If no such restrictions are specified, then all values are conforming.
When a user agent has to split a string on commas, it must use the following algorithm:
-
Let input be the string being parsed.
-
Let position be a pointer into input, initially pointing at the start of the string.
-
Let tokens be an ordered list of tokens, initially empty.
-
Token: If position is past the end of input, jump to the last step.
-
Collect a sequence of characters that are not U+002C COMMA characters (,). Let s be the resulting sequence (which might be the empty string).
-
Append s to tokens.
-
If position is not past the end of input, then the character at position is a U+002C COMMA character (,); advance position past that character.
-
Jump back to the step labeled token.
-
Return tokens.
2.4.9. References
A valid hash-name reference to an element of type type is a
string consisting of a U+0023 NUMBER SIGN character (#) followed by a string which exactly matches
the value of the name
attribute of an element with type type in
the document.
The rules for parsing a hash-name reference to an element of type type, given a context node scope, are as follows:
-
If the string being parsed does not contain a U+0023 NUMBER SIGN character, or if the first such character in the string is the last character in the string, then return null and abort these steps.
-
Let s be the string from the character immediately after the first U+0023 NUMBER SIGN character in the string being parsed up to the end of that string.
-
Return the first element of type type in tree order in the subtree rooted at scope that has an
id
attribute whose value is a case-sensitive match for s or aname
attribute whose value is a compatibility caseless match for s.
2.4.10. Media queries
A string is a valid media query list if it matches the <media-query-list>
production of the Media Queries specification. [MEDIAQ]
A string matches the environment of the user if it is the empty string, a string consisting of only space characters, or is a media query list that matches the user’s environment according to the definitions given in the Media Queries specification. [MEDIAQ]
2.5. URLs
2.5.1. Terminology
A URL is a valid URL if it conforms to the authoring conformance requirements in the WHATWG URL specification. [URL]
A string is a valid non-empty URL if it is a valid URL but it is not the empty string.
A string is a valid URL potentially surrounded by spaces if, after stripping leading and trailing whitespace from it, it is a valid URL.
A string is a valid non-empty URL potentially surrounded by spaces if, after stripping leading and trailing whitespace from it, it is a valid non-empty URL.
This specification defines the URL about:legacy-compat
as a reserved,
though unresolvable, about:
URL, for use in DOCTYPEs in HTML documents when needed for compatibility with XML tools. [RFC6694]
This specification defines the URL about:srcdoc
as a reserved, though
unresolvable, about:
URL, that is used as the document’s address of iframe
srcdoc
documents. [RFC6694]
The fallback base URL of a Document
object is the absolute URL obtained by running these substeps:
-
If document is an
iframe
srcdoc
document, then return the document base URL of the Document’s browsing context’s browsing context container’s node document. -
If document’s URL is
about:blank
, and the Document’s browsing context has a creator browsing context, then return the creator base URL. -
Return document’s URL.
The document base URL of a Document
object is the absolute URL obtained by running these substeps:
-
If there is no
base
element that has anhref
attribute in theDocument
, then the document base URL is theDocument
's fallback base URL; abort these steps. -
Otherwise, the document base URL is the frozen base URL of the first
base
element in theDocument
that has anhref
attribute, in tree order.
2.5.2. Parsing URLs
Parsing a URL is the process of taking a URL string and obtaining the URL record that it implies. While this process is defined in the WHATWG URL specification, this specification defines a wrapper for convenience. [URL]
This wrapper is only useful when the character encoding for the URL parser has to match that of the document or environment settings object for legacy reasons. When that is not the case the URL parser can be used directly.
To parse a URL url, relative to either a document or environment settings object, the user agent must use the following steps. Parsing a URL either results in failure or a resulting URL string and resulting URL record.
-
Let encoding be document’s character encoding, if document was given, and environment settings object’s API URL character encoding otherwise.
-
Let baseURL be document’s base URL, if document was given, and environment settings object’s API base URL otherwise.
-
Let urlRecord be the result of applying the URL parser to url, with baseURL and encoding.
-
If urlRecord is failure, then abort these steps with an error.
-
Let urlString be the result of applying the URL serializer to urlRecord.
-
Return urlString as the resulting URL string and urlRecord as the resulting URL record.
2.5.3. Dynamic changes to base URLs
When a document’s document base URL changes, all elements in that document are affected by a base URL change.
The following are base URL change steps, which run when an element is affected by a base URL change (as defined by the DOM specification):
- If the element creates a hyperlink
-
If the URL identified by the hyperlink is being shown to the user, or if any
data derived from that URL is affecting the display, then the
href
attribute should be reparsed relative to the element’s node document and the UI updated appropriately.For example, the CSS
:link
/:visited
pseudo-classes might have been affected. - If the element is a
q
,blockquote
,ins
, ordel
element with acite
attribute - If the URL identified by the
cite
attribute is being shown to the user, or if any data derived from that URL is affecting the display, then the URL should be reparsed relative to the element’s node document and the UI updated appropriately. - Otherwise
-
The element is not directly affected.
For instance, changing the base URL doesn’t affect the image displayed by
img
elements, although subsequent accesses of thesrc
IDL attribute from script will return a new absolute URL that might no longer correspond to the image being shown.
2.6. Fetching resources
2.6.1. Terminology
User agents can implement a variety of transfer protocols, but this specification mostly defines behavior in terms of HTTP. [HTTP]
The HTTP GET method is equivalent to the default retrieval action of the protocol. For example, RETR in FTP. Such actions are idempotent and safe, in HTTP terms.
The HTTP response codes are equivalent to statuses in other protocols that have the same basic meanings. For example, a "file not found" error is equivalent to a 404 code, a server error is equivalent to a 5xx code, and so on.
The HTTP headers are equivalent to fields in other protocols that have the same basic meaning. For example, the HTTP authentication headers are equivalent to the authentication aspects of the FTP protocol.
A referrer source is either a Document
or a URL.
To create a potential-CORS request, given a url, corsAttributeState, and an optional same-origin fallback flag, run these steps:
-
Let mode be "
no-cors
" if corsAttributeState is No CORS, and "cors
" otherwise. -
If same-origin fallback flag is set and mode is "
no-cors
", set mode to "same-origin
". -
Let credentialsMode be "
include
". -
If corsAttributeState is Anonymous, set credentialsMode to "
same-origin
". -
Let request be a new request whose URL is url, destination is "
subresource
", mode is mode, credentials mode is credentialsMode, and whose use-URL-credentials flag is set.
2.6.2. Processing model
When a user agent is to fetch a resource or URL, optionally from an origin origin, optionally using a specific referrer source as an override referrer source, and optionally with any of a synchronous flag, a manual redirect flag, a force same-origin flag, and a block cookies flag, the following steps must be run. (When a URL is to be fetched, the URL identifies a resource to be obtained.)
-
If there is a specific override referrer source, and it is a URL, then let referrer be the override referrer source, and jump to the step labeled clean referrer.
-
Let document be the appropriate
Document
as given by the following list:- If there is a specific override referrer source
- The override referrer source.
- When navigating
- The active document of the source browsing context.
- When fetching resources for an element
- The element’s
Document
.
-
While document is an
iframe
srcdoc
document, let document be document’s browsing context’s browsing context container’sDocument
instead. -
If the origin of Document is not a scheme/host/port tuple, then set referrer to the empty string and jump to the step labeled Clean referrer.
-
Let referrer be the document’s address of document.
-
Clean referrer: Apply the URL parser to referrer and let parsed referrer be the resulting URL record.
-
Let referrer be the result of applying the URL serializer to parsed referrer, with the exclude fragment flag set.
-
If referrer is not the empty string, is not a
data:
URL, and is not the URL "about:blank
", then generate the address of the resource from which Request-URIs are obtained as required by HTTP for theReferer
(sic) header from referrer. [HTTP]Otherwise, the
Referer
(sic) header must be omitted, regardless of its value. -
If the algorithm was not invoked with the synchronous flag, perform the remaining steps in parallel.
-
If the
Document
with which any tasks queued by this algorithm would be associated doesn’t have an associated browsing context, then abort these steps. -
This is the main step.
If the resource is to be obtained from an application cache, then use the data from that application cache, as if it had been obtained in the manner appropriate given its URL.
If the resource is identified by an absolute URL, and the resource is to be obtained using an idempotent action (such as an HTTP GET or equivalent), and it is already being downloaded for other reasons (e.g., another invocation of this algorithm), and this request would be identical to the previous one (e.g., same
Accept
andOrigin
headers), and the user agent is configured such that it is to reuse the data from the existing download instead of initiating a new one, then use the results of the existing download instead of starting a new one.Otherwise, if the resource is identified by an absolute URL with a scheme that does not define a mechanism to obtain the resource (e.g., it is a
mailto:
URL) or that the user agent does not support, then act as if the resource was an HTTP 204 No Content response with no other metadata.Otherwise, if the resource is identified by the URL
about:blank
, then the resource is immediately available and consists of the empty string, with no metadata.Otherwise, at a time convenient to the user and the user agent, download (or otherwise obtain) the resource, applying the semantics of the relevant specifications (e.g., performing an HTTP GET or POST operation, or reading the file from disk, or expanding
data:
URLs, etc).For the purposes of the
Referer
(sic) header, use the address of the resource from which Request-URIs are obtained generated in the earlier step.For the purposes of the
Origin
header, if the fetching algorithm was explicitly initiated from an origin, then the origin that initiated the HTTP request is origin. Otherwise, this is a request from a "privacy-sensitive" context. [ORIGIN] -
If the algorithm was not invoked with the block cookies flag, and there are cookies to be set, update the cookies. [COOKIES]
-
If the fetched resource is an HTTP redirect or equivalent, then:
- If the force same-origin flag is set and the URL of the target of the redirect does not have the same origin as the URL for which the fetch algorithm was invoked
- Abort these steps and return failure from this algorithm, as if the remote host could not be contacted.
- If the manual redirect flag is set
- Continue, using the fetched resource (the redirect) as the result of the algorithm. If the calling algorithm subsequently requires the user agent to transparently follow the redirect, then the user agent must resume this algorithm from the main step, but using the target of the redirect as the resource to fetch, rather than the original resource.
- Otherwise
-
First, apply any relevant requirements for redirects (such as showing any appropriate
prompts). Then, redo main step, but using the target of the redirect as the
resource to fetch, rather than the original resource. For HTTP requests, the new request
must include the same headers as the original request, except for headers for which
other requirements are specified (such as the
Host
header). [HTTP]The HTTP specification requires that 301, 302, and 307 redirects, when applied to methods other than the safe methods, not be followed without user confirmation. That would be an appropriate prompt for the purposes of the requirement in the paragraph above. [HTTP]
-
If the algorithm was not invoked with the synchronous flag: When the resource is available, or if there is an error of some description, queue a task that uses the resource as appropriate. If the resource can be processed incrementally, as, for instance, with a progressively interlaced JPEG or an HTML file, additional tasks may be queued to process the data as it is downloaded. The task source for these tasks is the networking task source.
Otherwise, return the resource or error information to the calling algorithm.
If the user agent can determine the actual length of the resource being fetched for an
instance of this algorithm, and if that length is finite, then that length is the file’s size. Otherwise, the subject of the algorithm (that is, the resource being fetched)
has no known size. (For example, the HTTP Content-Length
header might
provide this information.)
The user agent must also keep track of the number of bytes downloaded for each instance of this algorithm. This number must exclude any out-of-band metadata, such as HTTP headers.
The navigation processing model handles redirects itself, overriding the redirection handling that would be done by the fetching algorithm.
Whether the type sniffing rules apply to the fetched resource depends on the algorithm that invokes the rules — they are not always applicable.
2.6.3. Encrypted HTTP and related security concerns
Anything in this specification that refers to HTTP also applies to HTTP-over-TLS, as represented
by URLs representing the https
scheme. [HTTP]
User agents should report certificate errors to the user and must either refuse to download resources sent with erroneous certificates or must act as if such resources were in fact served with no encryption.
User agents should warn the user that there is a potential problem whenever the user visits a page that the user has previously visited, if the page uses less secure encryption on the second visit.
Not doing so can result in users not noticing man-in-the-middle attacks.
If a user connects to a server with full encryption, but the page then refers to an external resource that has an expired certificate, then the user agent will act as if the resource was unavailable, possibly also reporting the problem to the user. If the user agent instead allowed the resource to be used, then an attacker could just look for "secure" sites that used resources from a different host and only apply man-in-the-middle attacks to that host, for example taking over scripts in the page.
If a user bookmarks a site that uses a CA-signed certificate, and then later revisits that site directly but the site has started using a self-signed certificate, the user agent could warn the user that a man-in-the-middle attack is likely underway, instead of simply acting as if the page was not encrypted.
2.6.4. Determining the type of a resource
The Content-Type metadata of a resource must be obtained and interpreted in a manner consistent with the requirements of the MIME Sniffing specification. [MIMESNIFF]
The computed type of a resource must be found in a manner consistent with the requirements given in the MIME Sniffing specification for finding the computed media type of the relevant sequence of octets. [MIMESNIFF]
The rules for sniffing images specifically and the rules for distinguishing if a resource is text or binary are also defined in the MIME Sniffing specification. Both sets of rules return a MIME type as their result. [MIMESNIFF]
It is imperative that the rules in the MIME Sniffing specification be followed exactly. When a user agent uses different heuristics for content type detection than the server expects, security problems can occur. For more details, see the MIME Sniffing specification. [MIMESNIFF]
2.6.5. Extracting character encodings from meta
elements
The algorithm for extracting a character encoding from a meta
element,
given a string s, is as follows. It either returns a character encoding or nothing.
-
Let position be a pointer into s, initially pointing at the start of the string.
-
Loop: Find the first seven characters in s after position that are an ASCII case-insensitive match for the word "
charset
". If no such match is found, return nothing and abort these steps. -
Skip any space characters that immediately follow the word "
charset
" (there might not be any). -
If the next character is not a U+003D EQUALS SIGN (=), then move position to point just before that next character, and jump back to the step labeled loop.
-
Skip any space characters that immediately follow the equals sign (there might not be any).
-
Process the next character as follows:
- If it is a U+0022 QUOTATION MARK character (") and there is a later U+0022 QUOTATION
MARK character (") in s
- If it is a U+0027 APOSTROPHE character (') and there is a later U+0027 APOSTROPHE character (') in s
- Return the result of getting an encoding from the substring that is between this character and the next earliest occurrence of this character.
- If it is an unmatched U+0022 QUOTATION MARK character (")
- If it is an unmatched U+0027 APOSTROPHE character (')
- If there is no next character
- If it is an unmatched U+0027 APOSTROPHE character (')
- Return nothing.
- Otherwise
- Return the result of getting an encoding from the substring that consists of this character up to but not including the first space character or U+003B SEMICOLON character (;), or the end of s, whichever comes first.
- If it is a U+0022 QUOTATION MARK character (") and there is a later U+0022 QUOTATION
MARK character (") in s
This algorithm is distinct from those in the HTTP specification (for example, HTTP doesn’t allow the use of single quotes and requires supporting a backslash-escape mechanism that is not supported by this algorithm). While the algorithm is used in contexts that, historically, were related to HTTP, the syntax as supported by implementations diverged some time ago. [HTTP]
2.6.6. CORS settings attributes
A CORS settings attribute is an enumerated attribute. The following table lists the keywords and states for the attribute — the keywords in the left column map to the states in the cell in the second column on the same row as the keyword.
Keyword | State | Brief description |
---|---|---|
anonymous
| Anonymous | Requests for the element will have their mode set to "cors " and
their credentials mode set to "same-origin ".
|
use-credentials
| Use Credentials | Requests for the element will have their mode set to "cors " and
their credentials mode set to "include ".
|
The empty string is also a valid keyword, and maps to the Anonymous state. The attribute’s invalid value default is the Anonymous state. For the purposes of reflection,
the canonical case for the Anonymous state is the anonymous
keyword. The missing value default, used when the attribute is omitted, is the No CORS state.
2.7. Common DOM interfaces
2.7.1. Reflecting content attributes in IDL attributes
Some IDL attributes are defined to reflect a particular content attribute. This means that on getting, the IDL attribute returns the current value of the content attribute, and on setting, the IDL attribute changes the value of the content attribute to the given value.
In general, on getting, if the content attribute is not present, the IDL attribute must act as if the content attribute’s value is the empty string; and on setting, if the content attribute is not present, it must first be added.
If a reflecting IDL attribute is a DOMString
attribute whose content attribute is
defined to contain a URL, then on getting, the IDL attribute must parse the
value of the content attribute relative to the element and return the resulting absolute URL if that was successful, or the empty string otherwise; and on setting, must
set the content attribute to the specified literal value. If the content attribute is absent,
the IDL attribute must return the default value, if the content attribute has one, or else the
empty string.
If a reflecting IDL attribute is a DOMString
attribute whose content attribute is
defined to contain one or more URLs, then on getting, the IDL attribute must split the
content attribute on spaces and return the concatenation of parsing each token URL
to an absolute URL relative to the element, with a single U+0020 SPACE character between
each URL, ignoring any tokens that did not resolve successfully. If the content attribute is
absent, the IDL attribute must return the default value, if the content attribute has one, or
else the empty string. On setting, the IDL attribute must set the content attribute to the
specified literal value.
If a reflecting IDL attribute is a DOMString
attribute whose content attribute is
an enumerated attribute, and the IDL attribute is limited to only known values,
then, on getting, the IDL attribute must return the conforming value associated with the state
the attribute is in (in its canonical case), if any, or the empty string if the attribute is in
a state that has no associated keyword value or if the attribute is not in a defined state (e.g.,
the attribute is missing and there is no missing value default); and on setting, the
content attribute must be set to the specified new value.
If a reflecting IDL attribute is a nullable DOMString
attribute whose content
attribute is an enumerated attribute, then, on getting, if the corresponding content
attribute is in its missing value default then the IDL attribute must return null,
otherwise, the IDL attribute must return the conforming value associated with the state the
attribute is in (in its canonical case); and on setting, if the new value is null, the content
attribute must be removed, and otherwise, the content attribute must be set to the specified new
value.
If a reflecting IDL attribute is a DOMString
attribute but doesn’t fall into any
of the above categories, then the getting and setting must be done in a transparent,
case-preserving manner.
If a reflecting IDL attribute is a boolean
attribute, then on getting the IDL
attribute must return true if the content attribute is set, and false if it is absent. On
setting, the content attribute must be removed if the IDL attribute is set to false, and must be
set to the empty string if the IDL attribute is set to true. (This corresponds to the rules for boolean content attributes.)
If a reflecting IDL attribute has a signed integer type (long
) then, on getting,
the content attribute must be parsed according to the rules for parsing signed integers,
and if that is successful, and the value is in the range of the IDL attribute’s type, the
resulting value must be returned. If, on the other hand, it fails or returns an out of range
value, or if the attribute is absent, then the default value must be returned instead, or 0 if
there is no default value. On setting, the given value must be converted to the shortest
possible string representing the number as a valid integer and then that string must be
used as the new content attribute value.
If a reflecting IDL attribute has a signed integer type (long
)
that is limited to only non-negative numbers then, on getting, the content attribute
must be parsed according to the rules for parsing non-negative integers, and if that
is successful, and the value is in the range of the IDL attribute’s type, the resulting value
must be returned. If, on the other hand, it fails or returns an out of range value, or if the
attribute is absent, the default value must be returned instead, or -1 if there is no
default value. On setting, if the value is negative, the user agent must throw an IndexSizeError
exception. Otherwise, the given value must be converted to the
shortest possible string representing the number as a valid non-negative integer and then
that string must be used as the new content attribute value.
If a reflecting IDL attribute has an unsigned integer type (unsigned long
)
then, on getting, the content attribute must be parsed according to the rules for parsing
non-negative integers, and if that is successful, and the value is in the range 0 to
2147483647 inclusive, the resulting value must be returned. If, on the other hand, it fails or
returns an out of range value, or if the attribute is absent, the default value must be returned
instead, or 0 if there is no default value. On setting, first, if the new value is in the range
0 to 2147483647, then let n be the new value, otherwise let n be the
default value, or 0 if there is no default value; then, n must be converted to the
shortest possible string representing the number as a valid non-negative integer and that
string must be used as the new content attribute value.
If a reflecting IDL attribute has an unsigned integer type (unsigned long
) that is limited to only non-negative numbers greater than zero, then the behavior is similar
to the previous case, but zero is not allowed. On getting, the content attribute must first be
parsed according to the rules for parsing non-negative integers, and if that is
successful, and the value is in the range 1 to 2147483647 inclusive, the resulting value must be
returned. If, on the other hand, it fails or returns an out of range value, or if the attribute
is absent, the default value must be returned instead, or 1 if there is no default value. On
setting, if the value is zero, the user agent must throw an IndexSizeError
exception. Otherwise, first, if the new value is in the range 1 to 2147483647, then let n be the new value, otherwise let n be the default value, or 1 if there is
no default value; then, n must be converted to the shortest possible string
representing the number as a valid non-negative integer and that string must be used as
the new content attribute value.
If a reflecting IDL attribute has a floating-point number type (double
or unrestricted double
), then, on getting, the content attribute must be parsed
according to the rules for parsing floating-point number values, and if that is
successful, the resulting value must be returned. If, on the other hand, it fails, or if the
attribute is absent, the default value must be returned instead, or 0.0 if there is no default
value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then that string must be used as the new content attribute value.
If a reflecting IDL attribute has a floating-point number type (double
or unrestricted double
) that is limited to numbers greater than zero, then
the behavior is similar to the previous case, but zero and negative values are not allowed. On
getting, the content attribute must be parsed according to the rules for parsing
floating-point number values, and if that is successful and the value is greater than 0.0,
the resulting value must be returned. If, on the other hand, it fails or returns an out of range
value, or if the attribute is absent, the default value must be returned instead, or 0.0 if
there is no default value. On setting, if the value is less than or equal to zero, then the
value must be ignored. Otherwise, the given value must be converted to the best representation of the number as a floating-point number and then that string must be used as the new content attribute value.
The values Infinity and Not-a-Number (NaN) values throw an exception on setting, as defined in the Web IDL specification. [WEBIDL]
If a reflecting IDL attribute has the type DOMTokenList
, then on getting it must return a DOMTokenList
object whose associated element is the element in question and whose associated
attribute’s local name is the name of the attribute in question. The same DOMTokenList
object must be returned every time for each attribute.
If a reflecting IDL attribute has the type HTMLElement
, or an interface that
descends from HTMLElement
, then, on getting, it must run the following algorithm
(stopping at the first point where a value is returned):
-
If the corresponding content attribute is absent, then the IDL attribute must return null.
-
Let candidate be the element that the
document.getElementById()
method would find when called on the content attribute’s element’s node document if it were passed as its argument the current value of the corresponding content attribute. -
If candidate is null, or if it is not type-compatible with the IDL attribute, then the IDL attribute must return null.
-
Otherwise, it must return candidate.
On setting, if the given element has an id
attribute, and has the same home subtree as the element of the attribute being set, and the given element is the
first element in that home subtree whose ID is the value of that id
attribute, then the content attribute must be set to the value of that id
attribute. Otherwise, the content attribute must be set to the empty string.
2.7.2. Collections
The HTMLFormControlsCollection
and HTMLOptionsCollection
interfaces are collections derived from the HTMLCollection
interface. The HTMLAllCollection
however, is independent as it has a variety of unique quirks that are not
desirable to inherit from HTMLCollection
.
2.7.2.1. The HTMLAllCollection
interface
The HTMLAllCollection
interface is used for the legacy document.all
attribute. It operates similarly to HTMLCollection
; it also supports a variety of
other legacy features required for web compatibility such as the ability to be invoked like a
function (legacycaller
).
All HTMLAllCollection
objects are rooted at a Document
and have a filter that
matches all elements, so the elements represented by the collection of an HTMLAllCollection
object consist of all the descendant elements of the root Document
.
[LegacyUnenumerableNamedProperties] interface HTMLAllCollection { readonly attribute unsigned long length; getter Element? (unsigned long index); getter (HTMLCollection or Element)? namedItem(DOMString name); legacycaller (HTMLCollection or Element)? item(optional DOMString nameOrItem); };
- collection .
length
- Returns the number of elements in the collection.
- element = collection .
item
(index)- element = collection(index)
- element = collection[index]
- element = collection(index)
- Returns the item with index index from the collection (determined by tree order.
- element = collection .
item
(name)- collection = collection .
item
(name)- element = collection .
namedItem
(name)- collection = collection .
namedItem
(name)- element = collection(name)
- collection = collection(name)
- element = collection[name]
- collection = collection[name]
- collection = collection .
-
Returns the item with ID or name name from the collection.
If there are multiple matching items, then an
HTMLCollection
object containing all those elements is returned.The
name
attribute’s value provides a name forbutton
,input
,select
, andtextarea
. Similarly,iframe
'sname
,object
'sname
,meta
'sname
,map
'sname
, andform
'sname
attribute’s value provides a name for their respective elements. Only the elements mentioned have a name for the purpose of this method.
The object’s supported property indices are as defined for HTMLCollection
objects.
The supported property names consist of the non-empty values of all the id
and name attributes of all the elements represented by the collection, in tree order, ignoring later duplicates, with the id
of an element preceding its name if it
contributes both, they differ from each other, and neither is the duplicate of an earlier entry.
On getting, the length
attribute must
return the number of nodes represented by the collection.
The indexed property getter must return the result of getting the "all"-indexed element from this HTMLAllCollection
given the passed index.
The namedItem(name)
method
must return the result of getting the "all"-named element or elements from this HTMLAllCollection
given name.
The item(nameOrIndex)
method
(and the legacycaller
behavior) must act according to the following algorithm:
-
If nameOrIndex was not provided, return null.
-
If nameOrIndex, converted to a JavaScript string value, is an array index property name, return the result of getting the "all"-indexed element from this
HTMLAllCollection
given the number represented by nameOrIndex. -
Return the result of getting the "all"-named element or elements from this
HTMLAllCollection
given nameOrIndex.
The following elements are considered "all"-named elements: a
, applet
, button
, embed
, form
, frame
, frameset
, iframe
, img
, input
, map
, meta
, object
, select
, and textarea
.
To get the "all"-indexed element from an HTMLAllCollection
collection given an index index, return the element
with index index in collection, or null if there is no such element at index.
To get the "all"-named element or elements from an HTMLAllCollection
collection given a name name, run the
following algorithm:
-
If name is the empty string, return null.
-
Let subCollection be an
HTMLCollection
object rooted at the sameDocument
as collection, whose filter matches only elements that are either:-
"all"-named elements with a name attribute equal to name, or,
-
elements with an ID equal to name.
-
-
If there is exactly one element in subCollection, then return that element.
-
Otherwise, if subCollection is empty, return null.
-
Otherwise, return subCollection.
2.7.2.2. The HTMLFormControlsCollection
interface
The HTMLFormControlsCollection
interface is used for collections of listed elements in form
elements.
interface HTMLFormControlsCollection : HTMLCollection { // inherits length and item() getter (RadioNodeList or Element)? namedItem(DOMString name); // shadows inherited namedItem() };
interface RadioNodeList : NodeList { attribute DOMString value; };
- collection .
length
- Returns the number of elements in the collection.
- element = collection .
item
(index)- element = collection[index]
- Returns the item with index index from the collection. The items are sorted in tree order.
- element = collection .
namedItem
(name)- radioNodeList = collection .
namedItem
(name)- element = collection[name]
- radioNodeList = collection[name]
- radioNodeList = collection .
-
Returns the item with ID or
name
name from the collection.If there are multiple matching items, then a
RadioNodeList
object containing all those elements is returned. - radioNodeList . value [ = value ]
-
Returns the value of the first checked radio button represented by the object.
Can be set, to check the first radio button with the given value represented by the object.
The object’s supported property indices are as defined for HTMLCollection
objects.
The supported property names consist of the non-empty values of all the id
and name
attributes of all the elements represented by the collection, in tree order, ignoring later duplicates, with the id
of an element preceding
its name
if it contributes both, they differ from each other, and neither is the
duplicate of an earlier entry.
The properties exposed in this way must be unenumerable.
The namedItem(name)
method must act according to the
following algorithm:
-
If name is the empty string, return null and stop the algorithm.
-
If, at the time the method is called, there is exactly one node in the collection that has either an
id
attribute or aname
attribute equal to name, then return that node and stop the algorithm. -
Otherwise, if there are no nodes in the collection that have either an
id
attribute or aname
attribute equal to name, then return null and stop the algorithm. -
Otherwise, create a new
RadioNodeList
object representing a live view of theHTMLFormControlsCollection
object, further filtered so that the only nodes in theRadioNodeList
object are those that have either anid
attribute or aname
attribute equal to name. The nodes in theRadioNodeList
object must be sorted in tree order. -
Return that
RadioNodeList
object.
Members of the RadioNodeList
interface inherited from the NodeList
interface must behave as they would on a NodeList
object.
The value
IDL attribute on the RadioNodeList
object, on
getting, must return the value returned by running the following steps:
-
Let element be the first element in tree order represented by the
RadioNodeList
object that is aninput
element whosetype
attribute is in the Radio Button state and whose checkedness is true. Otherwise, let it be null. -
If element is null, return the empty string.
-
If element is an element with no
value
attribute, return the string "on
". -
Otherwise, return the value of element’s
value
attribute.
On setting, the value
IDL attribute must run the following steps:
-
If the new value is the string "
on
": let element be the first element in tree order represented by theRadioNodeList
object that is aninput
element whosetype
attribute is in the Radio Button state and whosevalue
content attribute is either absent, or present and equal to the new value, if any. If no such element exists, then instead let element be null.Otherwise: let element be the first element in tree order represented by the
RadioNodeList
object that is aninput
element whosetype
attribute is in the Radio Button state and whosevalue
content attribute is present and equal to the new value, if any. If no such element exists, then instead let element be null. -
If element is not null, then set its checkedness to true.
2.7.2.3. The HTMLOptionsCollection
interface
The HTMLOptionsCollection
interface is used for collections of option
elements. It is always rooted on a select
element and has
attributes and methods that manipulate that element’s descendants.
interface HTMLOptionsCollection : HTMLCollection { // inherits item(), namedItem() attribute unsigned long length; // shadows inherited length setter void (unsigned long index, HTMLOptionElement? option); void add((HTMLOptionElement or HTMLOptGroupElement) element, optional (HTMLElement or long)? before = null); void remove(long index); attribute long selectedIndex; };
- collection .
length
[ = value ] -
Returns the number of elements in the collection.
When set to a smaller number, truncates the number of
option
elements in the corresponding container.When set to a greater number, adds new blank
option
elements to that container. - element = collection .
item
(index)- element = collection[index]
- Returns the item with index index from the collection. The items are sorted in tree order.
- collection[index] = element
-
When index is a greater number than the number of items in the collection, adds
new blank
option
elements in the corresponding container.When set to null, removes the item at index index from the collection.
When set to an
option
element, adds or replaces it at index index from the collection. - element = collection .
namedItem
(name)- element = collection[name]
-
Returns the item with ID or
name
name from the collection.If there are multiple matching items, then the first is returned.
- collection .
add
(element [, before ] ) -
Inserts element before the node given by before.
The before argument can be a number, in which case element is inserted before the item with that number, or an element from the collection, in which case element is inserted before that element.
If before is omitted, null, or a number out of range, then element will be added at the end of the list.
This method will throw a
HierarchyRequestError
exception if element is an ancestor of the element into which it is to be inserted. - collection .
remove
(index) - Removes the item with index index from the collection.
- collection .
selectedIndex
[ = value ] -
Returns the index of the first selected item, if any, or -1 if there is no selected
item.
Can be set, to change the selection.
The object’s supported property indices are as defined for HTMLCollection
objects.
On getting, the length
attribute must return the number of nodes represented by the collection.
On setting, the behavior depends on whether the new value is equal to, greater than, or less than
the number of nodes represented by the collection at that time. If the number is the same,
then setting the attribute must do nothing. If the new value is greater, then n new option
elements with no attributes and no child nodes must be appended to the select
element on which the HTMLOptionsCollection
is rooted, where n is the difference between the two numbers (new value minus old value). Mutation
events must be fired as if a DocumentFragment
containing the new option
elements had been inserted. If the new value is lower, then the last n nodes in the
collection must be removed from their parent nodes, where n is the difference between
the two numbers (old value minus new value).
Setting length
never removes or adds any optgroup
elements, and never
adds new children to existing optgroup
elements (though it can remove children from
them).
The supported property names consist of the non-empty values of all the id
and name
attributes of all the elements represented by the collection, in tree order, ignoring later duplicates, with the id
of an element preceding its name
if it contributes both, they differ from each other, and neither is the
duplicate of an earlier entry.
The properties exposed in this way must be unenumerable.
When the user agent is to set the value of a new indexed property or set the value of an existing indexed property for a given property index index to a new value value, it must run the following algorithm:
-
If value is null, invoke the steps for the
remove
method with index as the argument, and abort these steps. -
Let length be the number of nodes represented by the collection.
-
Let n be index minus length.
-
If n is greater than zero, then append a
DocumentFragment
consisting of n-1 newoption
elements with no attributes and no child nodes to theselect
element on which theHTMLOptionsCollection
is rooted. -
If n is greater than or equal to zero, append value to the
select
element. Otherwise, replace the indexth element in the collection by value.
The add(element, before)
method must act according
to the following algorithm:
-
If element is an ancestor of the
select
element on which theHTMLOptionsCollection
is rooted, then throw aHierarchyRequestError
exception and abort these steps. -
If before is an element, but that element isn’t a descendant of the
select
element on which theHTMLOptionsCollection
is rooted, then throw aNotFoundError
exception and abort these steps. -
If element and before are the same element, then return and abort these steps.
-
If before is a node, then let reference be that node. Otherwise, if before is an integer, and there is a beforeth node in the collection, let reference be that node. Otherwise, let reference be null.
-
If reference is not null, let parent be the parent node of reference. Otherwise, let parent be the
select
element on which theHTMLOptionsCollection
is rooted. -
Act as if the DOM
insertBefore()
method was invoked on the parent node, with element as the first argument and reference as the second argument.
The remove(index)
method must act according to the following
algorithm:
-
If the number of nodes represented by the collection is zero, abort these steps.
-
If index is not a number greater than or equal to 0 and less than the number of nodes represented by the collection, abort these steps.
-
Let element be the indexth element in the collection.
-
Remove element from its parent node.
The selectedIndex
IDL attribute must act like the identically named
attribute on the select
element on which the HTMLOptionsCollection
is
rooted
2.7.3. The DOMStringMap
interface
The DOMStringMap
interface represents a set of name-value pairs. It exposes these
using the scripting language’s native mechanisms for property access.
When a DOMStringMap
object is instantiated, it is associated with three algorithms,
one for getting the list of name-value pairs, one for setting names to certain values, and one for
deleting names.
[OverrideBuiltins] interface DOMStringMap { getter DOMString (DOMString name); setter void (DOMString name, DOMString value); deleter void (DOMString name); };
The supported property names on a DOMStringMap
object at any instant are the
names of each pair returned from the algorithm for getting the list of name-value pairs at that
instant, in the order returned.
To determine the value of a named property name in a DOMStringMap
, the user agent must return the value component of the name-value pair
whose name component is name in the list returned by the algorithm for getting the list
of name-value pairs.
To set the value of a named property name to value value, the algorithm for setting names to certain values must be run, passing name as the name and value as the value.
To delete an existing named property name, the algorithm for deleting names must be run, passing name as the name.
The DOMStringMap
interface definition here is only intended for JavaScript
environments. Other language bindings will need to define how DOMStringMap
is to be
implemented for those languages.
dataset
attribute on elements exposes the data-*
attributes on the
element.
Given the following fragment and elements with similar constructions:
<img class="tower" id="tower5" data-x="12" data-y="5" data-ai="robotarget" data-hp="46" data-ability="flames" src="towers/rocket.png" alt="Rocket Tower">
...one could imagine a function splashDamage()
that takes some arguments, the first
of which is the element to process:
function splashDamage(node, x, y, damage) { if (node.classList.contains('tower') && // checking the 'class' attribute node.dataset.x == x && // reading the 'data-x' attribute node.dataset.y == y) { // reading the 'data-y' attribute var hp = parseInt(node.dataset.hp); // reading the 'data-hp' attribute hp = hp - damage; if (hp < 0) { hp = 0; node.dataset.ai = 'dead'; // setting the 'data-ai' attribute delete node.dataset.ability; // removing the 'data-ability' attribute } node.dataset.hp = hp; // setting the 'data-hp' attribute } }
2.7.4. The DOMElementMap
interface
The DOMElementMap
interface represents a set of name-element mappings. It exposes
these using the scripting language’s native mechanisms for property access.
When a DOMElementMap
object is instantiated, it is associated with three algorithms,
one for getting the list of name-element mappings, one for mapping a name to a certain element,
and one for deleting mappings by name.
interface DOMElementMap { getter Element (DOMString name); setter creator void (DOMString name, Element value); deleter void (DOMString name); };
The supported property names on a DOMElementMap
object at any instant are the
names for each mapping returned from the algorithm for getting the list of name-element mappings
at that instant, in the order returned.
To determine the value of a named property name in a DOMElementMap
, the user agent must return the element component of the name-element
mapping whose name component is name in the list returned by the algorithm for getting
the list of name-element mappings.
To set the value of a new or existing named property name to value value, the algorithm for mapping a name to a certain element must be run, passing name as the name value as the element.
To delete an existing named property name, the algorithm for deleting mappings must be run, passing name as the name component of the mapping to be deleted.
The DOMElementMap
interface definition here is only intended for JavaScript
environments. Other language bindings will need to define how DOMElementMap
is to
be implemented for those languages.
2.7.5. Garbage collection
There is an implied strong reference from any IDL attribute that returns a pre-existing object to that object.
window.document
attribute on the Window
object means that there is a strong reference
from a Window
object to its Document
object. Similarly, there is
always a strong reference from a Document
to any descendant nodes, and from any
node to its owner node document. 2.8. Namespaces
The HTML namespace is: http://www.w3.org/1999/xhtml
The MathML namespace is: http://www.w3.org/1998/Math/MathML
The SVG namespace is: http://www.w3.org/2000/svg
The XLink namespace is: http://www.w3.org/1999/xlink
The XML namespace is: http://www.w3.org/XML/1998/namespace
The XMLNS namespace is: http://www.w3.org/2000/xmlns/
Data mining tools and other user agents that perform operations on content without running scripts, evaluating CSS or XPath expressions, or otherwise exposing the resulting DOM to arbitrary content, may "support namespaces" by just asserting that their DOM node analogs are in certain namespaces, without actually exposing the above strings.
In the HTML syntax, namespace prefixes and namespace declarations do not have the same effect as in XML. For instance, the colon has no special meaning in HTML element names.
2.9. Safe passing of structured data
This section uses the terminology and typographic conventions from the JavaScript specification. [ECMA-262]
2.9.1. Cloneable objects
Cloneable objects support being cloned across event loops. That is, they support
being cloned across Document
and Worker
boundaries, including across Document
s of
different origins. Not all objects are cloneable objects and not all
aspects of objects that are cloneable objects are necessarily preserved when cloned.
Platform objects have the following internal method:
[[Clone]] ( targetRealm, memory )
Unless specified otherwise, invoking the [[Clone]] internal method must
throw a "DataCloneError
" DOMException
. (By default, platform objects are not cloneable objects.)
Platform objects that are cloneable objects have a [[Clone]] internal method which is specified to run a series of steps. The result of running those steps must be a thrown exception or a clone of this, created in targetRealm. It is up such objects to define what cloning means for them.
Objects defined in the JavaScript specification are handled by the StructuredClone abstract operation directly.
2.9.2. Transferable objects
Transferable objects support being transferred across event loops. Transferring is effectively recreating the object while sharing a reference to the underlying data and then detaching the object being transferred. This is useful to transfer ownership of expensive resources. Not all objects are transferable objects and not all aspects of objects that are transferable objects are necessarily preserved when transferred.
Transferring is an irreversible and non-idempotent operation. Once an object has been transferred, it cannot be transferred, or indeed used, again.
Platform objects that are transferable objects have a [[Detached]] internal slot and the following internal method:
[[Transfer]] ( targetRealm )
Whereas all platform objects have a [[Clone]] internal method, not all have a [[Detached]] internal slot and a [[Transfer]] internal method.
Platform objects that are transferable objects must define the [[Transfer]] internal method such that it either throws an exception or returns a clone of this, created in targetRealm, with this’s underlying data shared with the return value, and this’s [[Detached]] internal slot value set to true. It is up to such objects to define what transfering means for them.
Objects defined in the JavaScript specification are handled by the StructuredCloneWithTransfer abstract operation directly. (Technically, by IsTransferable and TransferHelper.)
2.9.3. StructuredCloneWithTransfer ( input, transferList, targetRealm )
-
Let memory be an empty map.
The purpose of the memory map, both here and in the StructuredClone abstract operation, is to avoid cloning objects twice. This ends up preserving cycles and the identity of duplicate objects in graphs.
-
For each object transferable in transferList:
-
If IsTransferable(transferable) is false, then throw a "
DataCloneError
"DOMException
. -
Let placeholder be a user-agent-defined placeholder object.
-
Create an entry in memory with key transferable and value placeholder.
-
-
Let clone be the result of ? StructuredClone(input, targetRealm, memory).
-
Let outputTransferList be a new empty List.
-
For each object transferable in transferList:
-
Let placeholderResult be the value of the entry in memory whose key is transferable.
-
Let transferResult be ? TransferHelper(transferable, targetRealm).
-
Within clone, replace references to placeholderResult with transferResult, such that everything holding a reference to placeholderResult, now holds a reference to transferResult.
This is a rather unusual low-level operation for which no primitives are defined by JavaScript.
-
Add transferResult as the last element of outputTransferList.
-
-
Return { [[Clone]]: clone, [[transferList]]: outputTransferList }.
Originally the StructuredCloneWithTransfer abstract operation was known as
the "structured clone" algorithm. The StructuredClone abstract operation was known as the
"internal structured clone" algorithm. Transferring objects, now handled by the StructuredCloneWithTransfer abstract operation, were formerly handled by parts of the
algorithm of the postMessage()
method on the Window
object and the Window/postMessage()
method on the MessagePort
object.
2.9.4. StructuredClone ( input, targetRealm [ , memory ] )
-
If memory was not supplied, let memory be an empty map.
-
If memory contains an entry with key input, then return that entry’s value.
-
If Type(input) is Undefined, Null, Boolean, String, or Number, then return input.
-
If Type(input) is Symbol, then throw a "
DataCloneError
"DOMException
. -
Let deepClone be false.
-
If input has a [[BooleanData]] internal slot, then let output be a new Boolean object in targetRealm whose [[BooleanData]] internal slot value is the [[BooleanData]] internal slot value of input.
-
Otherwise, if input has a [[NumberData]] internal slot, then let output be a new Number object in targetRealm whose [NumberData]] internal slot value is the [[NumberData]] internal slot value of input.
-
Otherwise, if input has a [[StringData]] internal slot, then let output be a new String object in targetRealm whose [[StringData]] internal slot value is the [[StringData]] internal slot value of input.
-
Otherwise, if input has a [[DateValue]] internal slot, then let output be a new Date object in targetRealm whose [[DateValue]] internal slot value is the [[DateValue]] internal slot value of input.
-
Otherwise, if input has a [[RegExpMatcher]] internal slot, then let output be a new RegExp object in targetRealm whose [[RegExpMatcher]] internal slot value is the [[RegExpMatcher]] internal slot value of input, whose [[OriginalSource]] internal slot value is the [[OriginalSource]] internal slot value of input, and whose whose [[OriginalFlags]] internal slot value is the [[OriginalFlags]] internal slot value of input.
-
Otherwise, if input has an [[ArrayBufferData]] internal slot, then:
-
If IsDetachedBuffer(input) is true, then throw a "
DataCloneError
"DOMException
. -
Let outputArrayBuffer be the %ArrayBuffer% intrinsic object in targetRealm.
-
Let output be ? CloneArrayBuffer(input, 0, outputArrayBuffer).
-
-
Otherwise, if input has a [[ViewedArrayBuffer]] internal slot, then:
-
Let buffer be the value of input’s [[ViewedArrayBuffer]] internal slot.
-
Let bufferClone be ? StructuredClone(buffer, targetRealm, memory)}}.
-
If input has a [[DataView]] internal slot, then let output be a new DataView object in targetRealm whose [[DataView]] internal slot value is true, whose [[ViewedArrayBuffer]] internal slot value is bufferClone, whose [[ByteLength]] internal slot value is the [[ByteLength]] internal slot value of input, and whose [[ByteOffset]] internal slot value is the [[ByteOffset]] internal slot value of input.
-
Otherwise:
-
Assert: input has a [[TypedArrayName]] internal slot.
-
Let constructor be the intrinsic object listed in column one of The TypedArray Constructors table for the value of input’s [[TypedArrayName]] internal slot in targetRealm.
-
Let byteOffset be input’s [[ByteOffset]] internal slot value.
-
Let length be input’s [[ArrayLength]] internal slot value.
-
Let output be ? TypedArrayCreate(constructor, « bufferClone, byteOffset, length »).
-
-
-
Otherwise, if input has [[MapData]] internal slot, then:
-
Let output be a new Map object in targetRealm whose [[MapData]] internal slot value is a new empty List.
-
Set deepClone to true.
-
-
Otherwise, if input has [[SetData]] internal slot, then:
-
Let output be a new Set object in targetRealm whose [[SetData]] internal slot value is a new empty List.
-
Set deepClone to true.
-
-
Otherwise, if input is an Array exotic object, then:
-
Let inputLen be OrdinaryGetOwnProperty(input, "
length
").[[value]]. -
Let outputProto be the %ArrayPrototype% intrinsic object in targetRealm.
-
Let output be ! ArrayCreate(inputLen, outputProto).
-
Set deepClone to true.
-
-
Otherwise, if input has a [[Clone]] internal method, then let output be ? input.[[Clone]](targetRealm, memory).
-
Otherwise, if IsCallable(input)}} is true, then throw a "
DataCloneError
"DOMException
. -
Otherwise, if input has any internal slot other than [[Prototype]] or [[Extensible]], then throw a "
DataCloneError
"DOMException
.For instance, a [[PromiseState]] or [[WeakMapData]] internal slot.
-
Otherwise, if input is an exotic object, then throw a "
DataCloneError
"DOMException
. -
Otherwise:
-
Let output be a new Object in targetRealm.
-
Set deepClone to true.
-
-
Create an entry in memory whose key is input and value is output.
-
If deepClone is true, then:
-
If input has a [[MapData]] internal slot, then:
-
Let inputList the value of input’s [[MapData]] internal slot.
-
Let copiedList be a new empty List.
-
Repeat for each Record { [[key]], [[value]] } entry that is an element of inputList,
-
Let copiedEntry be a new Record { [[key]]: entry.[[key]], [[value]]: entry.[[value]] }.
-
If copiedEntry.[[key]] is not empty, append copiedEntry as the last element of copiedList.
-
-
Let outputList be the value of output’s [[MapData]] internal slot.
-
For each Record { [[key]], [[value]] } entry that is an element of copiedList,
-
Let outputKey be ? StructuredClone(entry.[[key]], targetRealm, memory).
-
Let outputValue be ? StructuredClone(entry.[[value]], targetRealm, memory).
-
Add { [[key]]: outputKey, [[value]]: outputValue } as the last element of outputList.
-
-
-
Otherwise, if input has a [[SetData]] internal slot, then:
-
Let copiedList be a copy of the value of input’s [[SetData]] internal slot.
-
Let outputList be the value of output’s [[SetData]] internal slot.
-
For each entry that is an element of copiedList that is not empty,
-
Let outputEntry be ? StructuredClone(entry, targetRealm, memory).
-
Add outputEntry as the last element of outputList.
-
-
-
Otherwise:
-
Let enumerableKeys be a new empty List.
-
For each key in ! input.[[OwnPropertyKeys]]():
-
If Type(key) is String, then:
-
Let inputDesc be ! input.[[GetOwnProperty]](key).
-
If inputDesc.[[Enumerable]] is true, then add key as the last element of enumerableKeys.
-
-
-
For each key in enumerableKeys:
-
If ! HasOwnProperty(input, key) is true, then:
-
Let inputValue be ? input.[[Get]](key, input).
-
Let outputValue be ? StructuredClone(inputValue, targetRealm, memory).
-
Perform ? CreateDataProperty(output, key, outputValue).
-
-
-
-
-
Return output.
In general implementations will need to use some kind of serialization and marshalling to implement the creation of objects in targetRealm, as targetRealm could be in a different event loop and not easily accessible to the code that invokes StructuredCloneWithTransfer or StructuredClone.
2.9.5. IsTransferable ( O )
-
Assert: Type(O) is Object.
-
If O has an [[ArrayBufferData]] internal slot, then:
-
If IsDetachedBuffer(O) is true, then return false.
-
Return true.
-
-
Otherwise, if O has a [[Detached]] internal slot, then:
-
If O’s [[Detached]] internal slot value is true, then return false.
-
Return true.
-
-
Return false.
2.9.6. TransferHelper ( input, targetRealm )
-
If input has an [[ArrayBufferData]] internal slot, then:
-
Let output be a new
ArrayBuffer
object in targetRealm whose [[ArrayBufferByteLength]] internal slot value is the [[ArrayBufferByteLength]] internal slot value of input, and whose [[ArrayBufferData]] internal slot value is the [[ArrayBufferData]] internal slot value of input. -
Perform ! DetachArrayBuffer(input).
-
Return output.
-
-
Return ? input.[[Transfer]](targetRealm).
3. Semantics, structure, and APIs of HTML documents
3.1. Documents
Every XML and HTML document in an HTML user agent is represented by a Document
object. [DOM]
The document’s address is the URL associated with a Document
(as
defined in the DOM standard). It is initially set when the Document
is created, but
that can change during the lifetime of the Document
; for example, it changes when
the user navigates to a fragment identifier on the page and when the pushState()
method is called with a new URL. [DOM]
Interactive user agents typically expose the document’s address in their user interface. This is the primary mechanism by which a user can tell if a site is attempting to impersonate another.
When a Document
is created by a script using the createDocument()
or createHTMLDocument()
APIs, the document’s address is the same as the document’s address of the responsible document specified by the script’s settings object, and the Document
is both ready for post-load tasks and completely loaded immediately.
The document’s referrer is an absolute URL that can be set when the Document
is created. If it is not explicitly set, then its value is the empty string.
Each Document
object has a reload override flag that is originally unset.
The flag is set by the document.open()
and document.write()
methods in
certain situations. When the flag is set, the Document
also has a reload override buffer which is a Unicode string that is used as the source of the
document when it is reloaded.
When the user agent is to perform an overridden reload, given a source browsing context, it must act as follows:
-
Let source be the value of the browsing context’s active document’s reload override buffer.
-
Let address be the browsing context’s active document’s URL.
-
Let HTTPS state be the HTTPS state of the browsing context’s active document.
-
Let CSP list be the CSP list of the browsing context’s active document.
-
Navigate the browsing context to a new response whose body is source, CSP list is CSP list and HTTPS state is HTTPS state, with the exceptions enabled flag and replacement enabled. The source browsing context is that given to the overridden reload algorithm. When the navigate algorithm creates a
Document
object for this purpose, set thatDocument
's reload override flag and set its reload override buffer to source. Rethrow any exceptions.When it comes time to set the document’s address in the navigation algorithm, use address as the override URL.
3.1.1. The Document object
The DOM specification defines a Document
interface, which this specification extends
significantly:
enum DocumentReadyState { "loading", "interactive", "complete" }; [OverrideBuiltins] partial /*sealed*/ interface Document { // resource metadata management [PutForwards=href, Unforgeable] readonly attribute Location? location; attribute DOMString domain; readonly attribute DOMString referrer; attribute DOMString cookie; readonly attribute DOMString lastModified; readonly attribute DocumentReadyState readyState; // DOM tree accessors getter object (DOMString name); attribute DOMString title; attribute DOMString dir; attribute HTMLElement? body; readonly attribute HTMLHeadElement? head; [SameObject] readonly attribute HTMLCollection images; [SameObject] readonly attribute HTMLCollection embeds; [SameObject] readonly attribute HTMLCollection plugins; [SameObject] readonly attribute HTMLCollection links; [SameObject] readonly attribute HTMLCollection forms; [SameObject] readonly attribute HTMLCollection scripts; NodeList getElementsByName(DOMString elementName); readonly attribute HTMLScriptElement? currentScript; // dynamic markup insertion Document open(optional DOMString type = "text/html", optional DOMString replace = ""); WindowProxy open(DOMString url, DOMString name, DOMString features, optional boolean replace = false); void close(); void write(DOMString... text); void writeln(DOMString... text); // user interaction readonly attribute WindowProxy? defaultView; readonly attribute Element? activeElement; boolean hasFocus(); attribute DOMString designMode; boolean execCommand(DOMString commandId, optional boolean showUI = false, optional DOMString value = ""); boolean queryCommandEnabled(DOMString commandId); boolean queryCommandIndeterm(DOMString commandId); boolean queryCommandState(DOMString commandId); boolean queryCommandSupported(DOMString commandId); DOMString queryCommandValue(DOMString commandId); // special event handler IDL attributes that only apply to Document objects [LenientThis] attribute EventHandler onreadystatechange; }; Document implements GlobalEventHandlers; Document implements DocumentAndElementEventHandlers;
The Document
has an HTTPS state (an HTTPS state value),
initially "none
", which represents the security properties of the network channel
used to deliver the Document
's data.
The Document
has a CSP list, which is a list of Content Security Policy objects active in this context. The list is empty unless otherwise
specified.
3.1.2. Resource metadata management
- document .
referrer
-
Returns the address of the
Document
from which the user navigated to this one, unless it was blocked or there was no such document, in which case it returns the empty string.The
noreferrer
link type can be used to block the referrer.
referrer
attribute must return the document’s referrer. - document .
cookie
[ = value ] -
Returns the HTTP cookies that apply to the
Document
. If there are no cookies or cookies can’t be applied to this resource, the empty string will be returned.Can be set, to add a new cookie to the element’s set of HTTP cookies.
If the contents are sandboxed into a unique origin (e.g., in an
iframe
with thesandbox
attribute), a "SecurityError
"DOMException
will be thrown on getting and setting.
The cookie
attribute represents the cookies of
the resource identified by the document’s address.
A Document
object that falls into one of the following conditions is a cookie-averse Document
object:
-
A
Document
that has no browsing context. -
A
Document
whose address does not use a server-based naming authority.
On getting, if the document is a cookie-averse Document
object, then
the user agent must return the empty string. Otherwise, if the Document
's origin is an opaque origin, the user agent must throw a
"SecurityError
" DOMException
. Otherwise, the user agent must return the cookie-string for the document’s address for a "non-HTTP" API, decoded
using UTF-8 decode without BOM. [COOKIES]
On setting, if the document is a cookie-averse Document
object, then
the user agent must do nothing. Otherwise, if the Document
's origin is
an opaque origin, the user agent must throw a "SecurityError
" DOMException
.
Otherwise, the user agent must act as it would when receiving a set-cookie-string for the document’s address via a "non-HTTP" API, consisting of the new value encoded as UTF-8. [COOKIES] [ENCODING]
Since the cookie
attribute is accessible across frames, the path restrictions on
cookies are only a tool to help manage which cookies are sent to which parts of the site, and
are not in any way a security feature.
The cookie
attribute’s getter and setter synchronously access shared state. Since
there is no locking mechanism, other browsing contexts in a multiprocess user agent can modify
cookies while scripts are running. A site could, for instance, try to read a cookie, increment
its value, then write it back out, using the new value of the cookie as a unique identifier
for the session; if the site does this twice in two different browser windows at the same
time, it might end up using the same "unique" identifier for both sessions, with potentially
disastrous effects.
- document .
lastModified
-
Returns the date of the last modification to the document, as reported by the server, in the
form "
MM/DD/YYYY hh:mm:ss
", in the user’s local time zone.If the last modification date is not known, the current time is returned instead.
lastModified
attribute, on getting, must return the date and time of
the Document
's source file’s last modification, in the user’s local time zone, in
the following format:
-
The month component of the date.
-
A U+002F SOLIDUS character (/).
-
The day component of the date.
-
A U+002F SOLIDUS character (/).
-
The year component of the date.
-
A U+0020 SPACE character.
-
The hours component of the time.
-
A U+003A COLON character (:).
-
The minutes component of the time.
-
A U+003A COLON character (:).
-
The seconds component of the time.
All the numeric components above, other than the year, must be given as two ASCII digits representing the number in base ten, zero-padded if necessary. The year must be given as the shortest possible string of four or more ASCII digits representing the number in base ten, zero-padded if necessary.
The Document
's source file’s last modification date and time must be derived from
relevant features of the networking protocols used, e.g., from the value of the HTTP Last-Modified
header of the document, or from metadata in the file system for local
files. If the last modification date and time are not known, the attribute must return the
current date and time in the above format.
- document .
readyState
-
Returns "
loading
" while theDocument
is loading, "interactive
" once it is finished parsing but still loading sub-resources, and "complete
" once it has loaded.The
readystatechange
event fires on theDocument
object when this value changes.
Document
object
is created, it must have its current document readiness set to the string
"loading
" if the document is associated with an HTML parser, an XML parser, or an XSLT processor, and to the string "complete
"
otherwise. Various algorithms during page loading affect this value. When the value is set, the
user agent must fire a simple event named readystatechange
at the Document
object.
A Document
is said to have an active parser if it is associated with an HTML parser or an XML parser that has not yet been stopped or
The readyState
IDL attribute must, on getting, return the current
document readiness.
3.1.3. DOM tree accessors
The html
element of a document is the document’s root element, if there is
one and it’s an html
element, or null otherwise.
- document .
head
- Returns the
head
element.
The head
element of a document is the first head
element that
is a child of the html
element, if there is one, or null otherwise.
head
attribute, on getting, must return
the head
element of the document (a head
element or null). - document .
title
[ = value ] -
Returns the document’s title, as given by the
title
element for HTML and as given by the SVGtitle
element for SVG.Can be set, to update the document’s title. If there is no appropriate element to update, the new value is ignored.
The title
element of a document is the first title
element
in the document (in tree order), if there is one, or null otherwise.
title
attribute must, on getting, run the following algorithm:
-
If the root element is an
svg
element in the SVG namespace, then let value be a concatenation of the data of all the childText
nodes of the firsttitle
element in the SVG namespace that is a child of the root element. [SVG11] -
Otherwise, let value be a concatenation of the data of all the child
Text
nodes of thetitle
element, in tree order, or the empty string if thetitle
element is null. -
Strip and collapse whitespace in value.
-
Return value.
On setting, the steps corresponding to the first matching condition in the following list must be run:
- If the root element is an
svg
element in the SVG namespace [SVG11] -
-
Let element be the first
title
element in the SVG namespace that is a child of the root element, if any. If there isn’t one, create atitle
element in the SVG namespace, insert it as the first child of the root element, and let element be that element. [SVG11] -
Act as if the
textContent
IDL attribute of element was set to the new value being assigned.
-
- If the root element is in the HTML namespace
-
-
If the
title
element is null and thehead
element is null, then abort these steps. -
If the
title
element is null, then create a newtitle
element and append it to thehead
element, and let element be the newly created element; otherwise, let element be thetitle
element. -
Act as if the
textContent
IDL attribute of element was set to the new value being assigned.
-
- Otherwise
- Do nothing.
- document .
body
[ = value ] -
Returns the
body
element.Can be set, to replace the
body
element.If the new value is not a
body
orframeset
element, this will throw aHierarchyRequestError
exception.
The body
element of a document is the first child of
the html
element that is either a body
element or a frameset
element. If there is no such element, it is null.
body
attribute, on getting, must return the body
element of
the document (either a body
element, a frameset
element, or null). On
setting, the following algorithm must be run:
-
If the new value is not a
body
orframeset
element, then throw aHierarchyRequestError
exception and abort these steps. -
Otherwise, if the new value is the same as the
body
element, do nothing. Abort these steps. -
Otherwise, if the
body
element is not null, then replace that element with the new value in the DOM, as if the root element’sreplaceChild()
method had been called with the new value and the incumbentbody
element as its two arguments respectively, then abort these steps. -
Otherwise, if there is no root element, throw a
HierarchyRequestError
exception and abort these steps. -
Otherwise, the
body
element is null, but there’s a root element. Append the new value to the root element.
- document .
images
- Returns an
HTMLCollection
of theimg
elements in theDocument
. - document .
embeds
- document .
plugins
- document .
- Return an
HTMLCollection
of theembed
elements in theDocument
. - document .
links
- Returns an
HTMLCollection
of thea
andarea
elements in theDocument
that havehref
attributes. - document .
forms
- Return an
HTMLCollection
of theform
elements in theDocument
. - document .
scripts
- Return an
HTMLCollection
of thescript
elements in theDocument
.
images
attribute must return an HTMLCollection
rooted
at the Document
node, whose filter matches only img
elements.
The embeds
attribute must return an HTMLCollection
rooted
at the Document
node, whose filter matches only embed
elements.
The plugins
attribute must return the same object as that returned by
the embeds
attribute.
The links
attribute must return an HTMLCollection
rooted at
the Document
node, whose filter matches only a
elements with href
attributes and area
elements with href
attributes.
The forms
attribute must return an HTMLCollection
rooted at
the Document
node, whose filter matches only form
elements.
The scripts
attribute must return an HTMLCollection
rooted
at the Document
node, whose filter matches only script
elements.
- collection = document .
getElementsByName
(name) - Returns a
NodeList
of elements in theDocument
that have aname
attribute with the value name.
getElementsByName(name)
method takes a string name, and must return a live NodeList
containing all the html elements in that document that have a name
attribute whose value is
equal to the name argument (in a case-sensitive manner), in tree order.
When the method is invoked on a Document
object again with the same argument, the
user agent may return the same as the object returned by the earlier call. In other cases, a new NodeList
object must be returned. - document .
currentScript
-
Returns the
script
element that is currently executing. In the case of reentrantscript
execution, returns the one that most recently started executing amongst those that have not yet finished executing.Returns null if the
Document
is not currently executing ascript
element (e.g., because the running script is an event handler, or a timeout).
currentScript
attribute, on getting, must return the value to which
it was most recently initialized. When the Document
is created, the currentScript
must be initialized to null. The Document
interface supports named properties. The supported property names at any moment consist of the values of the name
content attributes of all the applet
, exposed embed
, form
, iframe
, img
, and exposed object
elements in the Document
that have non-empty name
content attributes,
and the values of the id
content attributes of all the applet
and exposed object
elements in the Document
that have non-empty id
content attributes, and the values of the id
content attributes of
all the img
elements in the Document
that have both non-empty name
content attributes and non-empty id
content attributes. The supported property names must be in tree order, ignoring later duplicates, with
values from id
attributes coming before values from name
attributes
when the same element contributes both.
To determine the value of a named property name when the Document
object is indexed for property retrieval, the user agent
must return the value obtained using the following steps:
-
Let elements be the list of named elements with the name name in the
Document
.There will be at least one such element, by definition.
-
If elements has only one element, and that element is an
iframe
element, then return theWindowProxy
object of the nested browsing context represented by thatiframe
element, and abort these steps. -
Otherwise, if elements has only one element, return that element and abort these steps.
-
Otherwise return an
HTMLCollection
rooted at theDocument
node, whose filter matches only named elements with the name name.
Named elements with the name name, for the purposes of the above algorithm, are those that are either:
-
applet
, exposedembed
,form
,iframe
,img
, or exposedobject
elements that have aname
content attribute whose value is name, or -
applet
or exposedobject
elements that have anid
content attribute whose value is name, or -
img
elements that have anid
content attribute whose value is name, and that have a non-emptyname
content attribute present also.
An embed
or object
element is said to be exposed if it has
no exposed object
ancestor, and, for object
elements, is
additionally either not showing its fallback content or has no object
or embed
descendants.
The dir
attribute on the Document
interface is defined along with the dir
content attribute.
3.1.4. Loading XML documents
partial interface XMLDocument { boolean load(DOMString url); };
The load(url)
method must run the following steps:
-
Let document be the
XMLDocument
object on which the method was invoked. -
Parse url, relative to the entry settings object. If this is not successful, throw a "
SyntaxError
"DOMException
and abort these steps. Otherwise, let urlRecord be the resulting URL record. -
If urlRecord’s origin is not the same as the origin of document, throw a "
SecurityError
"DOMException
and abort these steps. -
Remove all child nodes of document, without firing any mutation events.
-
Set the current document readiness of document to "
loading
". -
Run the remainder of these steps in parallel, and return true from the method.
-
Let result be a
Document
object. -
Let success be false.
-
Let request be a new request whose URL is urlRecord, client is entry settings object, destination is "
subresource
", synchronous flag is set, mode is "same-origin
", credentials mode is "same-origin
", and whose use-URL-credentials flag is set. -
Let response be the result of fetching request.
-
If response’s Content-Type metadata is an XML MIME type, then run these substeps:
-
Create a new XML parser associated with the result document.
-
Pass this parser response’s body.
-
If there is an XML well-formedness or XML namespace well-formedness error, then remove all child nodes from result. Otherwise let success be true.
-
-
Queue a task to run the following steps.
-
Set the current document readiness of document to "
complete
". -
Replace all the children of document by the children of result (even if it has no children), firing mutation events as if a
DocumentFragment
containing the new children had been inserted. -
Fire a simple event named
load
at document.
-
3.2. Elements
3.2.1. Semantics
Elements, attributes, and attribute values in HTML are defined (by this specification) to have
certain meanings (semantics). For example, the ol
element represents an ordered list,
and the lang
attribute represents the language of the content.
These definitions allow HTML processors, like web browsers and search engines, to present documents and applications consistently in different contexts.
h1
and h2
elements represent headings.
<!doctype html> <html lang="en"> <head> <title>Favorite books</title> </head> <body> <header> <img src="logo.png" alt="Favorite books logo"> </header> <main> <h1>Favorite books</h1> <p>These are a few of my favorite books.</p> <h2>The Belgariad</h2> <p>Five books by David and Leigh Eddings.</p> <h2>The Hitchhiker’s Guide to the Galaxy</h2> <p>A trilogy of five books by Douglas Adams.</p> </main> </body> </html>
This semantic information is critical to assistive technologies. For example, a screen reader will query the browser for semantic information and use that information to present the document or application in synthetic speech.
In some cases assistive technologies use semantic information to provide additional functionality.
A speech recognition tool might provide a voice command for moving focus to the start of the main
element for example.
When the appropriate HTML element or attribute is not used, it deprives HTML processors of valuable semantic information.
<!doctype html> <html lang="en"> <head> <title>Favorite books</title> </head> <body> <div class="header"> <img src="logo.png" alt="Favorite books logo"> </div> <div class="main"> <span class="largeHeading">Favorite books</span> <p>These are a few of my favorite books.</p> <span class="smallHeading">The Belgariad</span> <p>Five books by David and Leigh Eddings.</p> <span class="smallHeading">The Hitchhiker’s Guide to the Galaxy</span> <p>A trilogy of five books by Douglas Adams.</p> </div> </body> </html>
A document can change dynamically while it is being processed. Scripting and other mechanisms can be used to change attribute values, text, or the entire document structure. The semantics of a document are therefore based on the document’s state at a particular instance in time, but may also change in response to external events. User agents must update their presentation of the document to reflect these changes.
audio
element is used to play a music track. The controls
attribute is used to show the user
agent player, and as the music plays the controls are updated to indicate progress. The available
semantic information is updated in response to these changes.
<audio src="comfortablynumb.mp3" controls>
3.2.2. Elements in the DOM
The nodes representing html elements in the DOM must implement, and expose to scripts, the interfaces listed for them in the relevant sections of this specification. This includes html elements in XML documents, even when those documents are in another context (e.g., inside an XSLT transform).
Elements in the DOM represent things; that is, they have intrinsic meaning, also known as semantics.
For example, an ol
element represents an ordered list.
The basic interface, from which all the html elements' interfaces inherit, and which must be used by elements that have no additional requirements, is the HTMLElement
interface.
interface HTMLElement : Element { // metadata attributes attribute DOMString title; attribute DOMString lang; attribute boolean translate; attribute DOMString dir; [SameObject] readonly attribute DOMStringMap dataset; // user interaction attribute boolean hidden; void click(); attribute long tabIndex; void focus(); void blur(); attribute DOMString accessKey; attribute boolean draggable; [PutForwards=value] readonly attribute DOMTokenList dropzone; attribute HTMLMenuElement? contextMenu; attribute boolean spellcheck; void forceSpellCheck(); }; HTMLElement implements GlobalEventHandlers; HTMLElement implements DocumentAndElementEventHandlers; HTMLElement implements ElementContentEditable;
interface HTMLUnknownElement : HTMLElement { };
The HTMLElement
interface holds methods and attributes related to a number of
disparate features, and the members of this interface are therefore described in various different
sections of this specification.
HTMLUnknownElement
interface must be used for html elements that are not
defined by this specification (or other applicable specifications). 3.2.3. Element definitions
Each element in this specification has a definition that includes the following information:
-
Categories
-
A list of categories to which the element belongs. These are used when defining the content models for each element.
-
Contexts in which this element can be used
-
A non-normative description of where the element can be used. This information is redundant with the content models of elements that allow this one as a child, and is provided only as a convenience.
For simplicity, only the most specific expectations are listed. For example, an element that is both flow content and phrasing content can be used anywhere that either flow content or phrasing content is expected, but since anywhere that flow content is expected, phrasing content is also expected (since all phrasing content is flow content), only "where phrasing content is expected" will be listed.
-
Content model
-
A normative description of what content must be included as children and descendants of the element.
-
Tag omission in text/html
-
A non-normative description of whether, in the
text/html
syntax, the start and end tags can be omitted. This information is redundant with the normative requirements given in the optional tags section, and is provided in the element definitions only as a convenience. -
Content attributes
-
A normative list of attributes that may be specified on the element (except where otherwise disallowed), along with non-normative descriptions of those attributes. (The content to the left of the dash is normative, the content to the right of the dash is not.)
-
Allowed ARIA role attribute values
-
A normative list of ARIA role attribute values that may be specified on the element (except where otherwise disallowed). Each value is linked to a non normative description.
-
Links to the Global aria-* attributes list and the allowed roles, states and properties table.
-
DOM interface
-
A normative definition of a DOM interface that such elements must implement.
This is then followed by a description of what the element represents, along with any additional normative conformance criteria that may apply to authors and implementations. Examples are sometimes also included.
3.2.3.1. Attributes
Except where otherwise specified, attributes on html elements may have any string value, including the empty string. Except where explicitly stated, there is no restriction on what text can be specified in such attributes.
3.2.4. Content models
Each element defined in this specification has a content model: a description of the element’s
expected contents. An HTML element must have contents that match the requirements
described in the element’s content model. The contents of an element are its children
in the DOM, except for template
elements, where the children are those in the template contents (a separate DocumentFragment
assigned to the element when
the element is created).
The space characters are always allowed between elements. User agents represent these
characters between elements in the source markup as Text
nodes in the DOM. Empty Text
nodes and Text
nodes consisting of just sequences of those
characters are considered inter-element whitespace.
Inter-element whitespace, comment nodes, and processing instruction nodes must be ignored when establishing whether an element’s contents match the element’s content model or not, and must be ignored when following algorithms that define document and element semantics.
Thus, an element A is said to be preceded or followed by a second element B if A and B have the same parent node and there are no other
element nodes or Text
nodes (other than inter-element whitespace) between
them. Similarly, a node is the only child of an element if that element contains no other
nodes other than inter-element whitespace, comment nodes, and processing instruction
nodes.
Authors must not use html elements anywhere except where they are explicitly allowed, as defined for each element, or as explicitly required by other specifications. For XML compound documents, these contexts could be inside elements from other namespaces, if those elements are defined as providing the relevant contexts.
content
element. When its type
attribute has the value xhtml
, the Atom specification requires
that it contain a single HTML div
element. Thus, a div
element is
allowed in that context, even though this is not explicitly normatively stated by this
specification. [RFC4287] In addition, html elements may be orphan nodes (i.e., without a parent node).
td
element and storing it in a global variable in a
script is conforming, even though td
elements are otherwise only supposed to be
used inside tr
elements.
var data = { name: "Banana", cell: document.createElement('td'), };
3.2.4.1. The "nothing" content model
When an element’s content model is nothing, the element must contain no Text
nodes (other than inter-element whitespace) and no element nodes.
Most HTML elements whose content model is "nothing" are also, for convenience, void elements (elements that have no end tag in the HTML syntax). However, these are entirely separate concepts.
3.2.4.2. Kinds of content
Each element in HTML falls into zero or more categories that group elements with similar characteristics together. The following broad categories are used in this specification:
- §3.2.4.2.1 Metadata content
- §3.2.4.2.2 Flow content
- §3.2.4.2.3 Sectioning content
- §3.2.4.2.4 Heading content
- §3.2.4.2.5 Phrasing content
- §3.2.4.2.6 Embedded content
- §3.2.4.2.7 Interactive content
Some elements also fall into other categories, which are defined in other parts of this specification.
These categories are related as follows:
Sectioning content, heading content, phrasing content, embedded content, and interactive content are all types of flow content. Metadata is sometimes flow content. Metadata and interactive content are sometimes phrasing content. Embedded content is also a type of phrasing content, and sometimes is interactive content.
Other categories are also used for specific purposes, e.g., form controls are specified using a number of categories to define common requirements. Some elements have unique requirements and do not fit into any particular category.
3.2.4.2.1. Metadata content
Metadata content is content that sets up the presentation or behavior of the rest of the content, or that sets up the relationship of the document with other documents, or that conveys other "out of band" information.
3.2.4.2.2. Flow content
Most elements that are used in the body of documents and applications are categorized as flow content.
a
abbr
address
area
(if it is a descendant of amap
element)article
aside
audio
b
bdi
bdo
blockquote
br
button
canvas
cite
code
data
datalist
del
details
dfn
div
dl
em
embed
fieldset
figure
footer
form
h1
h2
h3
h4
h5
h6
header
hr
i
iframe
img
input
ins
kbd
keygen
label
main
map
mark
math
menu
meter
nav
noscript
object
ol
output
p
picture
pre
progress
q
ruby
s
samp
script
section
select
small
span
strong
sub
sup
svg
table
template
textarea
time
u
ul
var
video
wbr
- Text
3.2.4.2.3. Sectioning content
Sectioning content is content that defines the scope of headings and footers.
Each sectioning content element potentially has a heading and an outline. See the section on §4.3.10 Headings and sections for further details.
There are also certain elements that are sectioning roots. These are distinct from sectioning content, but they can also have an outline.
3.2.4.2.4. Heading content
Heading content defines the header of a section (whether explicitly marked up using sectioning content elements, or implied by the heading content itself).
3.2.4.2.5. Phrasing content
Phrasing content is the text of the document, as well as elements that mark up that text at the intra-paragraph level. Runs of phrasing content form paragraphs.
a
abbr
area
(if it is a descendant of amap
element)audio
b
bdi
bdo
br
button
canvas
cite
code
data
datalist
del
dfn
em
embed
i
iframe
img
input
ins
kbd
keygen
label
map
mark
math
meter
noscript
object
output
picture
progress
q
ruby
s
samp
script
select
small
span
strong
sub
sup
svg
template
textarea
time
u
var
video
wbr
- Text
Most elements that are categorized as phrasing content can only contain elements that are themselves categorized as phrasing content, not any flow content.
Text, in the context of content models, means either nothing, or Text
nodes. Text is sometimes used as a content model on its own, but is also phrasing content, and can be inter-element whitespace (if the Text
nodes are empty or contain just space characters).
Text
nodes and attribute values must consist of Unicode characters, must not
contain U+0000 characters, must not contain permanently undefined Unicode characters
(noncharacters), and must not contain control characters other than space characters.
This specification includes extra constraints on the exact value of Text
nodes and
attribute values depending on their precise context.
For elements in HTML, the constraints of the Text content model also depends on the kind of element. For instance, an "<
" inside a textarea
element does
not need to be escaped in HTML because textarea
is an escapable raw text element.
(This does not apply to XHTML. In XHTML, the kind of element doesn’t affect the constraints
of content model: Text.)
3.2.4.2.6. Embedded content
Embedded content is content that imports another resource into the document, or content from another vocabulary that is inserted into the document.
Elements that are from namespaces other than the HTML namespace and that convey content but not metadata, are embedded content for the purposes of the content models defined in this specification. (For example, MathML, or SVG.)
Some embedded content elements can have fallback content: content that is to be used when the external resource cannot be used (e.g., because it is of an unsupported format). The element definitions state what the fallback is, if any.
3.2.4.2.7. Interactive content
Interactive content is content that is specifically intended for user interaction.
a
(if thehref
attribute is present)audio
(if thecontrols
attribute is present)button
details
embed
iframe
img
(if theusemap
attribute is present)-
input
(if thetype
attribute is not in the state) keygen
label
select
textarea
video
(if thecontrols
attribute is present)
The tabindex
attribute can also make any element into interactive content.
3.2.4.2.8. Palpable content
As a general rule, elements whose content model allows any flow content or phrasing content should have at least one node in its contents that is palpable content and that does not have the hidden
attribute specified.
Palpable content makes an element non-empty by providing either some descendant non-empty text, or else something users can hear (audio
elements) or view
(video
or img
or canvas
elements) or otherwise interact
with (for example, interactive form controls).
This requirement is not a hard requirement, however, as there are many cases where an element can be empty legitimately, for example when it is used as a placeholder which will later be filled in by a script, or when the element is part of a template and would on most pages be filled in but on some pages is not relevant.
Conformance checkers are encouraged to provide a mechanism for authors to find elements that fail to fulfill this requirement, as an authoring aid.
The following elements are palpable content:
a
abbr
address
article
aside
audio
(if thecontrols
attribute is present)b
bdi
bdo
blockquote
button
canvas
cite
code
data
details
dfn
div
dl
(if the element’s children include at least one name-value group)em
embed
fieldset
figure
footer
form
h1
h2
h3
h4
h5
h6
header
i
iframe
img
-
input
(if thetype
attribute is not in the state) ins
kbd
keygen
label
main
map
mark
math
meter
nav
object
-
ol
(if the element’s children include at least oneli
element) output
p
pre
progress
q
ruby
s
samp
section
select
small
span
strong
sub
sup
svg
table
textarea
time
u
-
ul
(if the element’s children include at least oneli
element) var
video
- Text that is not inter-element whitespace
3.2.4.2.9. Script-supporting elements
Script-supporting elements are those that do not represent anything themselves (i.e., they are not rendered), but are used to support scripts, e.g., to provide functionality for the user.
The following elements are script-supporting elements:
3.2.4.3. Transparent content models
Some elements are described as transparent; they have "transparent" in the description of their content model. The content model of a transparent element is derived from the content model of its parent element: the elements required in the part of the content model that is "transparent" are the same elements as required in the part of the content model of the parent of the transparent element in which the transparent element finds itself.
ins
element inside a ruby
element cannot contain an rt
element, because the part of the ruby
element’s content model that
allows ins
elements is the part that allows phrasing content, and the rt
element is not phrasing content. In some cases, where transparent elements are nested in each other, the process has to be applied iteratively.
<p><object><param><ins><map><a href="/">Apples</a></map></ins></object></p>
To check whether "Apples" is allowed inside the a
element, the content models are
examined. The a
element’s content model is transparent, as is the map
element’s, as is the ins
element’s, as is the part of the object
element’s in which the ins
element is found. The object
element is
found in the p
element, whose content model is phrasing content. Thus,
"Apples" is allowed, as text is phrasing content.
When a transparent element has no parent, then the part of its content model that is "transparent" must instead be treated as accepting any flow content.
3.2.4.4. Paragraphs
The term paragraph as defined in this section is used for more than just the definition
of the p
element. The paragraph concept defined here is used to describe how
to interpret documents. The p
element is merely one of several ways of marking up a paragraph.
A paragraph is typically a run of phrasing content that forms a block of text with one or more sentences that discuss a particular topic, as in typography, but can also be used for more general thematic grouping. For instance, an address is also a paragraph, as is a part of a form, a byline, or a stanza in a poem.
<section> <h2>Example of paragraphs</h2> This is the <em>first</em> paragraph in this example. <p>This is the second.</p> <!-- This is not a paragraph. --> </section>
Paragraphs in flow content are defined relative to what the document looks like without the a
, ins
, del
, and map
elements complicating
matters, since those elements, with their hybrid content models, can straddle paragraph
boundaries, as shown in the first two examples below.
Generally, having elements straddle paragraph boundaries is best avoided. Maintaining such markup can be difficult.
ins
and del
elements around some of the markup to show that the text was changed (though in
this case, the changes admittedly don’t make much sense). Notice how this example has exactly
the same paragraphs as the previous one, despite the ins
and del
elements — the ins
element straddles the heading and the first paragraph, and
the del
element straddles the boundary between the two paragraphs.
<section> <ins><h1>Example of paragraphs</h1> This is the <em>first</em> paragraph in</ins> this example<del>. <p>This is the second.</p></del> <!-- This is not a paragraph. --> </section>
a
, ins
, del
, and map
elements in the document with their contents. Then, in view, for each run of sibling phrasing content nodes uninterrupted by other types of content, in an element that accepts content other than phrasing content as well as phrasing content, let first be the first
node of the run, and let last be the last node of the run. For each such run that
consists of at least one node that is neither embedded content nor inter-element whitespace, a paragraph exists in the original DOM from immediately before first to immediately after last. (Paragraphs can thus span across a
, ins
, del
, and map
elements.)
Conformance checkers may warn authors of cases where they have paragraphs that overlap each
other (this can happen with object
, video
, audio
, and canvas
elements, and indirectly through elements in other namespaces that allow
HTML to be further embedded therein, like svg
or math
).
A paragraph is also formed explicitly by p
elements.
The p
element can be used to wrap individual paragraphs when there would otherwise
not be any content other than phrasing content to separate the paragraphs from each other.
<header> Welcome! <a href="about.html"> This is home of... <h1>The Falcons!</h1> The Lockheed Martin multirole jet fighter aircraft! </a> This page discusses the F-16 Fighting Falcon’s innermost secrets. </header>
Here is another way of marking this up, this time showing the paragraphs explicitly, and splitting the one link element into three:
<header> <p>Welcome! <a href="about.html">This is home of...</a></p> <h1><a href="about.html">The Falcons!</a></h1> <p><a href="about.html">The Lockheed Martin multirole jet fighter aircraft!</a> This page discusses the F-16 Fighting Falcon’s innermost secrets.</p> </header>
<section> <h2>My Cats</h2> You can play with my cat simulator. <object data="cats.sim"> To see the cat simulator, use one of the following links: <ul> <li><a href="cats.sim">Download simulator file</a> <li><a href="https://sims.example.com/watch?v=LYds5xY4INU">Use online simulator</a> </ul> Alternatively, upgrade to the Mellblom Browser. </object> I’m quite proud of it. </section>
There are five paragraphs:
-
The paragraph that says "You can play with my cat simulator. object I’m quite proud of it.", where object is the
object
element. -
The paragraph that says "To see the cat simulator, use one of the following links:".
-
The paragraph that says "Download simulator file".
-
The paragraph that says "Use online simulator".
-
The paragraph that says "Alternatively, upgrade to the Mellblom Browser.".
The first paragraph is overlapped by the other four. A user agent that supports the "cats.sim" resource will only show the first one, but a user agent that shows the fallback will confusingly show the first sentence of the first paragraph as if it was in the same paragraph as the second one, and will show the last paragraph as if it was at the start of the second sentence of the first paragraph.
To avoid this confusion, explicit p
elements can be used. For example:
<section> <h2>My Cats</h2> <p>You can play with my cat simulator.</p> <object data="cats.sim"> <p>To see the cat simulator, use one of the following links:</p> <ul> <li><a href="cats.sim">Download simulator file</a> <li><a href="https://sims.example.com/watch?v=LYds5xY4INU">Use online simulator</a> </ul> <p>Alternatively, upgrade to the Mellblom Browser.</p> </object> <p>I’m quite proud of it.</p> </section>
3.2.5. Global attributes
The following attributes are common to and may be specified on all html elements (even those not defined in this specification):
-
class
-
hidden
-
spellcheck
-
style
-
tabindex
-
translate
bogus
" element does not have a dir
attribute as defined in this specification, despite having an attribute with
the literal name "dir
". Thus, the directionality of the inner-most span
element is "rtl
", inherited from the div
element
indirectly through the "bogus
" element.
<div xmlns="https://www.w3.org/1999/xhtml" dir="rtl"> <bogus xmlns="https://example.net/ns" dir="ltr"> <span xmlns="https://www.w3.org/1999/xhtml"> </span> </bogus> </div>
To enable assistive technology products to expose a more fine-grained interface than is otherwise
possible with HTML elements and attributes, a set of
annotations for assistive technology products can be specified (the ARIA role
and aria-*
attributes). [WAI-ARIA]
The following event handler content attributes may be specified on any HTML element:
-
onabort
-
onblur
* -
oncancel
-
oncanplay
-
oncanplaythrough
-
onchange
-
onclick
-
onclose
-
oncontextmenu
-
oncopy
-
oncuechange
-
oncut
-
ondblclick
-
ondrag
-
ondragend
-
ondragenter
-
ondragexit
-
ondragleave
-
ondragover
-
ondragstart
-
ondrop
-
ondurationchange
-
onemptied
-
onended
-
onerror
* -
onfocus
* -
oninput
-
oninvalid
-
onkeydown
-
onkeypress
-
onkeyup
-
onload
* -
onloadeddata
-
onloadedmetadata
-
onloadstart
-
onmousedown
-
onmouseenter
-
onmouseleave
-
onmousemove
-
onmouseout
-
onmouseover
-
onmouseup
-
onwheel
-
onpaste
-
onpause
-
onplay
-
onplaying
-
onprogress
-
onratechange
-
onreset
-
onresize
* -
onscroll
* -
onseeked
-
onseeking
-
onselect
-
onshow
-
onstalled
-
onsubmit
-
onsuspend
-
ontimeupdate
-
ontoggle
-
onvolumechange
-
onwaiting
The attributes marked with an asterisk have a different meaning when specified on body
elements as those elements expose event handlers of the Window
object with the same names.
While these attributes apply to all elements, they are not useful on all elements. For example,
only media elements will ever receive a volumechange
event fired by the user agent.
Custom data attributes (e.g., data-foldername
or data-msgid
) can
be specified on any HTML element, to store custom data specific to the page.
In HTML documents, elements in the HTML namespace may have an xmlns
attribute specified, if, and only if, it has the exact value
"https://www.w3.org/1999/xhtml
". This does not apply to XML documents.
In HTML, the xmlns
attribute has absolutely no effect. It is basically a talisman.
It is allowed merely to make migration to and from XHTML mildly easier. When parsed by an HTML parser, the attribute ends up in no namespace, not the
"https://www.w3.org/2000/xmlns/
" namespace like namespace declaration attributes in
XML do.
In XML, an xmlns
attribute is part of the namespace declaration mechanism, and an
element cannot actually have an xmlns
attribute in no namespace specified.
The XML specification also allows the use of the xml:space
attribute in the XML namespace on any element in an XML document. This attribute has no effect on html elements, as the default behavior in HTML is to preserve whitespace. [XML]
There is no way to serialize the xml:space
attribute on html elements in the text/html
syntax.
3.2.5.1. The id
attribute
The id
attribute specifies its element’s unique identifier (ID). [DOM]
The value must be unique amongst all the IDs in the element’s home subtree and must contain at least one character. The value must not contain any space characters.
There are no other restrictions on what form an ID can take; in particular, IDs can consist of just digits, start with a digit, start with an underscore, consist of just punctuation, etc.
An element’s unique identifier can be used for a variety of purposes, most notably as a way to link to specific parts of a document using fragment identifiers, as a way to target an element when scripting, and as a way to style a specific element from CSS.
id
attribute. 3.2.5.2. The title
attribute
The title
attribute represents advisory information for the
element, such as would be appropriate for a tooltip. On a link, this could be the title or a
description of the target resource; on an image, it could be the image credit or a description of
the image; on a paragraph, it could be a footnote or commentary on the text; on a citation, it
could be further information about the source; on interactive content, it could be a label
for, or instructions for, use of the element; and so forth. The value is text.
Relying on the title
attribute is currently discouraged as many user agents do not
expose the attribute in an accessible manner as required by this specification (e.g., requiring a
pointing device such as a mouse to cause a tooltip to appear, which excludes keyboard-only users
and touch-only users, such as anyone with a modern phone or tablet).
If this attribute is omitted from an element, then it implies that the title
attribute of the nearest ancestor HTML element with a title
attribute set is
also relevant to this element. Setting the attribute overrides this, explicitly stating that the
advisory information of any ancestors is not relevant to this element. Setting the attribute to
the empty string indicates that the element has no advisory information.
If the title
attribute’s value contains U+000A LINE FEED (LF) characters, the content
is split into multiple lines. Each U+000A LINE FEED (LF) character represents a line break.
title
attributes.
For instance, the following snippet actually defines an abbreviation’s expansion with a line break in it:
<p>My logs show that there was some interest in <abbr title="Hypertext Transport Protocol">HTTP</abbr> today.</p>
Some elements, such as link
, abbr
, and input
, define
additional semantics for the title
attribute beyond the semantics described above.
-
If the element is a
link
,style
,dfn
,abbr
, ormenuitem
element, then: if the element has atitle
attribute, return the value of that attribute, otherwise, return the empty string. -
Otherwise, if the element has a
title
attribute, then return its value. -
Otherwise, if the element has a parent element, then return the parent element’s advisory information.
-
Otherwise, return the empty string.
User agents should inform the user when elements have advisory information, otherwise the information would not be discoverable.
The title
IDL attribute must reflect the title
content attribute.
3.2.5.3. The lang
and xml:lang
attributes
The lang
attribute (in no namespace) specifies the primary language for
the element’s contents and for any of the element’s attributes that contain text. Its value must
be a valid BCP 47 language tag, or the empty string. Setting the attribute to the empty string
indicates that the primary language is unknown. [BCP47]
The lang
attribute in the XML namespace is defined in XML. [XML]
If these attributes are omitted from an element, then the language of this element is the same as the language of its parent element, if any.
The lang
attribute in no namespace may be used on any HTML element.
The lang
attribute in the XML namespace may be used on html elements in XML documents, as well as elements in other namespaces if the
relevant specifications allow it (in particular, MathML and SVG allow lang
attributes in the XML namespace to be specified on their elements). If both the lang
attribute in no namespace and the lang
attribute in the XML namespace are specified on the same element, they must have exactly the same value
when compared in an ASCII case-insensitive manner.
Authors must not use the lang
attribute in the XML namespace on html elements in HTML documents. To ease migration to and from XHTML, authors may
specify an attribute in no namespace with no prefix and with the literal localname
"xml:lang
" on html elements in HTML documents, but such attributes must
only be specified if a lang
attribute in no namespace is also specified, and both
attributes must have the same value when compared in an ASCII case-insensitive manner.
The attribute in no namespace with no prefix and with the literal localname
"xml:lang
" has no effect on language processing.
The language of HTML documents is indicated using a lang
attribute (on the HTML
element itself, to indicate the primary language of the document, and on individual elements,
to indicate a change in language). It provides an explicit indication to user agents about the
language of content, so an appropriate language dictionary can be used and, in the case of screen
readers and similar assistive technologies with voice output, the content is pronounced using the
correct voice / language library (where available). Setting of a language using the lang
attribute which does not match the language of the document or document parts will result in some
users being unable to understand the content.
To determine the language of a node, user agents must look at the nearest ancestor
element (including the element itself if the node is an element) that has a lang
attribute in the XML namespace set or is an HTML element and has a lang
in no namespace attribute set. That attribute specifies the language
of the node (regardless of its value).
If both the lang
attribute in no namespace and the lang
attribute in the XML namespace are set on an element, user
agents must use the lang
attribute in the XML namespace, and the lang
attribute in no namespace must be ignored for the purposes of
determining the element’s language.
If neither the node nor any of the node’s ancestors, including the root element, have either attribute set, but there is a pragma-set default language set, then that is the language of the node. If there is no pragma-set default language set, then language information from a higher-level protocol (such as HTTP), if any, must be used as the final fallback language instead. In the absence of any such language information, and in cases where the higher-level protocol reports multiple languages, the language of the node is unknown, and the corresponding language tag is the empty string.
For example, if a document is delivered over HTTP and the Content-Language
HTTP
header is specified with a value "en
" (and there is no pragma-set default
language), then for any element in the document that does not itself have a lang
attribute nor any ancestor of that element, the fallback language for the element will be
English. If the value of the Content-Language
header was
"de, fr, it
" then the language of the node is unknown. This article provides some additional guidance on the use of HTTP headers, and meta
elements for
providing language information.
If the resulting value is not a recognized language tag, then it must be treated as an unknown language having the given language tag, distinct from all other languages. For the purposes of round-tripping or communicating with other services that expect language tags, user agents should pass unknown language tags through unmodified, and tagged as being BCP 47 language tags, so that subsequent services do not interpret the data as another type of language description. [BCP47]
Thus, for instance, an element with lang="xyzzy"
would be matched by the selector :lang(xyzzy)
(e.g., in CSS), but it would not be matched by :lang(abcde)
, even though both are equally invalid. Similarly, if a Web browser
and screen reader working in unison communicated about the language of the element, the
browser would tell the screen reader that the language was "xyzzy", even if it knew it was
invalid, just in case the screen reader actually supported a language with that tag after all.
Even if the screen reader supported both BCP 47 and another syntax for encoding language
names, and in that other syntax the string "xyzzy" was a way to denote the Belarusian
language, it would be incorrect for the screen reader to then start treating text as
Belarusian, because "xyzzy" is not how Belarusian is described in BCP 47 codes (BCP 47 uses
the code "be" for Belarusian).
If the resulting value is the empty string, then it must be interpreted as meaning that the language of the node is explicitly unknown.
User agents may use the element’s language to determine proper processing or rendering (e.g., in the selection of appropriate fonts or pronunciations, for dictionary selection, or for the user interfaces of form controls such as date pickers).
The lang
IDL attribute must reflect the lang
content
attribute in no namespace.
3.2.5.4. The translate
attribute
The translate
attribute is an enumerated attribute that is used to
specify whether an element’s attribute values and the values of its Text
node
children are to be translated when the page is localized, or whether to leave them unchanged.
The attribute’s keywords are the empty string, yes
, and no
. The empty
string and the yes
keyword map to the yes state. The no
keyword
maps to the no state. In addition, there is a third state, the inherit state, which
is the missing value default (and the invalid value default).
Each element (even non-HTML elements) has a translation mode, which is in either the translate-enabled state or the no-translate state. If an HTML element’s translate
attribute is in the yes state, then the element’s translation mode is in the translate-enabled state; otherwise, if the element’s translate
attribute is in the no state, then the element’s translation mode is in the no-translate state. Otherwise, either the element’s translate
attribute is in the inherit state, or the element is not an HTML element and thus does not have a translate
attribute; in either case, the
element’s translation mode is in the same state as its parent element’s, if any, or in the translate-enabled state, if the element is a root element.
When an element is in the translate-enabled state, the element’s translatable attributes and the values of its Text
node children are to be
translated when the page is localized.
When an element is in the no-translate state, the element’s attribute values and the
values of its Text
node children are to be left as-is when the page is localized,
e.g., because the element contains a person’s name or a name of a computer program.
The following attributes are translatable attributes:
-
abbr
onth
elements -
content
onmeta
elements, if thename
attribute specifies a metadata name whose value is known to be translatable -
label
onmenuitem
,menu
,optgroup
,option
, andtrack
elements -
lang
on html elements; must be "translated" to match the language used in the translation -
placeholder
oninput
andtextarea
elements -
srcdoc
oniframe
elements; must be parsed and recursively processed -
style
on html elements; must be parsed and recursively processed (e.g., for the values of "content" properties) -
title
on all html elements -
value
oninput
elements with atype
attribute in the Button, submit button, or reset button state
The translate
IDL attribute must, on getting, return true if the
element’s translation mode is translate-enabled, and false otherwise. On setting,
it must set the content attribute’s value to "yes
" if the new value is true, and
set the content attribute’s value to "no
" otherwise.
<!DOCTYPE HTML> <html> <!-- default on the root element is translate=yes --> <head> <title>The Bee Game</title> <!-- implied translate=yes inherited from ancestors --> </head> <body> <p>The Bee Game is a text adventure game in English.</p> <p>When the game launches, the first thing you should do is type <kbd translate=no>eat honey</kbd>. The game will respond with:</p> <pre><samp translate=no>Yum yum! That was some good honey!</samp></pre> </body> </html>
3.2.5.5. The xml:base
attribute (XML only)
The xml:base
attribute is defined in XML Base. [XMLBASE]
The xml:base
attribute may be used on html elements of XML documents.
Authors must not use the xml:base
attribute on html elements in HTML documents.
3.2.5.6. The dir
attribute
The dir
attribute specifies the element’s text directionality. The attribute is an enumerated attribute with the following keywords and states:
-
The
ltr
keyword, which maps to the ltr state -
Indicates that the contents of the element are explicitly directionally isolated left-to-right text.
-
The
rtl
keyword, which maps to the rtl state -
Indicates that the contents of the element are explicitly directionally isolated right-to-left text.
-
The
auto
keyword, which maps to the auto state -
Indicates that the contents of the element are explicitly directionally isolated text, but that the direction is to be determined programmatically using the contents of the element (as described below).
The heuristic used by this state is very crude (it just looks at the first character with a strong directionality, in a manner analogous to the Paragraph Level determination in the bidirectional algorithm). Authors are urged to only use this value as a last resort when the direction of the text is truly unknown and no better server-side heuristic can be applied. [BIDI]
For
textarea
andpre
elements, the heuristic is applied on a per-paragraph level.
The attribute has no invalid value default and no missing value default.
The directionality of an element (any element, not just an HTML element) is
either "ltr
" or "rtl
", and is determined as per the first appropriate set of
steps from the following list:
- If the element’s
dir
attribute is in the ltr state- If the element is a root element and the
dir
attribute is not in a defined state (i.e., it is not present or has an invalid value)- If the element is an
input
element whosetype
attribute is in the Telephone state, and thedir
attribute is not in a defined state (i.e., it is not present or has an invalid value) - If the element is a root element and the
- The directionality of the element is "ltr".
- If the element’s
dir
attribute is in thertl
state - The directionality of the element is "rtl".
- If the element is an
input
element whosetype
attribute is in the Text, Search, Telephone, URL, or E-mail state, and thedir
attribute is in the auto state- If the element is a
textarea
element and thedir
attribute is in the auto state - If the element is a
-
If the element’s value contains a character of bidirectional character type AL or R,
and there is no character of bidirectional character type L anywhere before it in the
element’s value, then the directionality of the element is "rtl". [BIDI]
Otherwise, if the element’s value is not the empty string, or if the element is a root element, the directionality of the element is "ltr".
Otherwise, the directionality of the element is the same as the element’s parent element’s directionality.
- If the element’s
dir
attribute is in the auto state- If the element is a
bdi
element and thedir
attribute is not in a defined state (i.e., it is not present or has an invalid value) - If the element is a
-
Find the first character in tree order that matches the following criteria:
-
The character is from a
Text
node that is a descendant of the element whose directionality is being determined. -
The character is of bidirectional character type L, AL, or R. [BIDI]
-
The character is not in a
Text
node that has an ancestor element that is a descendant of the element whose directionality is being determined and that is either:
If such a character is found and it is of bidirectional character type AL or R, the directionality of the element is "rtl".
If such a character is found and it is of bidirectional character type L, the directionality of the element is "ltr".
Otherwise, if the element is a root element, the directionality of the element is "ltr".
Otherwise, the directionality of the element the same as the element’s parent element’s directionality.
-
- If the element has a parent element and the
dir
attribute is not in a defined state (i.e., it is not present or has an invalid value) - The directionality of the element is the same as the element’s parent element’s directionality.
Since the dir
attribute is only defined for html elements, it cannot be
present on elements from other namespaces. Thus, elements from other namespaces always just
inherit their directionality from their parent element, or, if they don’t have one,
default to "ltr
".
This attribute has rendering requirements involving the bidirectional algorithm.
The directionality of an attribute of an HTML element, which is used when the text of that attribute is to be included in the rendering in some manner, is determined as per the first appropriate set of steps from the following list:
- If the attribute is a directionality-capable attribute and the element’s
dir
attribute is in the auto state -
Find the first character (in logical order) of the attribute’s value that is of bidirectional
character type L, AL, or R. [BIDI]
If such a character is found and it is of bidirectional character type AL or R, the directionality of the attribute is "
rtl
".Otherwise, the directionality of the attribute is "
ltr
". - Otherwise
- The directionality of the attribute is the same as the element’s directionality.
The following attributes are directionality-capable attributes:
-
abbr
onth
elements -
content
onmeta
elements, if thename
attribute specifies a metadata name whose value is primarily intended to be human-readable rather than machine-readable -
label
onmenuitem
,menu
,optgroup
,option
, andtrack
elements -
title
on all html elements
- document .
dir
[ = value ] -
Returns the
html
element’sdir
attribute’s value, if any.Can be set, to either "
ltr
", "rtl
", or "auto
" to replace thehtml
element’sdir
attribute’s value.If there is no
html
element, returns the empty string and ignores new values.
dir
IDL attribute on an element must reflect the dir
content attribute of that element, limited to only known values.
The dir
IDL attribute on Document
objects must reflect the dir
content attribute of the html
element,
if any, limited to only known values. If there is no such element, then the attribute
must return the empty string and do nothing on setting.
Authors are strongly encouraged to use the dir
attribute to indicate text direction
rather than using CSS, since that way their documents will continue to render correctly even in
the absence of CSS (e.g., as interpreted by search engines).
<p dir=auto class="u1"><b><bdi>Student</bdi>:</b> How do you write "What’s your name?" in Arabic?</p> <p dir=auto class="u2"><b><bdi>Teacher</bdi>:</b> ما اسمك؟</p> <p dir=auto class="u1"><b><bdi>Student</bdi>:</b> Thanks.</p> <p dir=auto class="u2"><b><bdi>Teacher</bdi>:</b> That’s written "شكرًا".</p> <p dir=auto class="u2"><b><bdi>Teacher</bdi>:</b> Do you know how to write "Please"?</p> <p dir=auto class="u1"><b><bdi>Student</bdi>:</b> "من فضلك", right?</p>
Given a suitable style sheet and the default alignment styles for the p
element,
namely to align the text to the start edge of the paragraph, the resulting rendering could
be as follows:
As noted earlier, the auto
value is not a panacea. The final paragraph in this
example is misinterpreted as being right-to-left text, since it begins with an Arabic character,
which causes the "right?" to be to the left of the Arabic text.
3.2.5.7. The class
attribute
Every HTML element may have a class
attribute specified.
The attribute, if specified, must have a value that is a set of space-separated tokens representing the various classes that the element belongs to.
class
attribute is split on spaces. (Duplicates are
ignored.) Assigning classes to an element affects class matching in selectors in CSS, the getElementsByClassName()
method in the DOM, and other such features.
There are no additional restrictions on the tokens authors can use in the class
attribute, but authors are encouraged to use values that describe the nature of the content,
rather than values that describe the desired presentation of the content.
The className
and classList
IDL attributes,
defined in the DOM specification, reflect the class
content attribute. [DOM]
3.2.5.8. The style
attribute
There are no known native implementations of blocking the style
content attribute based on CSP3 directives. Therefore this feature should not be relied upon.
All html elements may have the style
content attribute set. This is a CSS styling attribute as defined by the CSS Styling Attribute Syntax specification. [CSS-STYLE-ATTR]
In user agents that support CSS, the attribute’s value must be parsed when the attribute is added or has its value changed, according to the rules given for CSS styling attributes. [CSS-STYLE-ATTR]
However, if the Should element’s inline behavior be blocked by Content Security Policy? algorithm returns
"Blocked
" when executed upon the
attribute’s element and "style attribute
", then the style
rules defined in the attribute’s value must not be applied to the element. [CSP3]
Documents that use style
attributes on any of their elements must still be
comprehensible and usable if those attributes were removed.
In particular, using the style
attribute to hide and show content, or to convey
meaning that is otherwise not included in the document, is non-conforming. (To hide and show
content, use the hidden
attribute.)
- element .
style
- Returns a
CSSStyleDeclaration
object for the element’sstyle
attribute.
style
IDL attribute is defined in the CSS Object Model (CSSOM)
specification. [CSSOM] span
element and the style
attribute to make those words show up in
the relevant colors in visual media.
<p>My sweat suit is <span style="color: green; background: transparent">green</span> and my eyes are <span style="color: blue; background: transparent">blue</span>.</p>
3.2.5.9. Embedding custom non-visible data with the data-*
attributes
A custom data attribute is an attribute in no namespace whose name starts with the
string "data-
", has at least one character after the hyphen, is XML-compatible, and contains no uppercase ASCII letters.
All attribute names on html elements in HTML documents get ASCII-lowercased automatically, so the restriction on ASCII uppercase letters doesn’t affect such documents.
Custom data attributes are intended to store custom data private to the page or application, for which there are no more appropriate attributes or elements.
These attributes are not intended for use by software that is not known to the administrators of the site that uses the attributes. For generic extensions that are to be used by multiple independent tools, either this specification should be extended to provide the feature explicitly, or a technology like microdata should be used (with a standardized vocabulary).
<ol> <li data-length="2m11s">Beyond The Sea</li> ... </ol>
It would be inappropriate, however, for the user to use generic software not associated with that music site to search for tracks of a certain length by looking at this data.
This is because these attributes are intended for use by the site’s own scripts, and are not a generic extension mechanism for publicly-usable metadata.
<p>The third <span data-mytrans-de="Anspruch">claim</span> covers the case of <span translate="no">HTML</span> markup.</p>
In this example, the "data-mytrans-de
" attribute gives specific text for the
MyTrans product to use when translating the phrase "claim" to German. However, the standard translate
attribute is used to tell it that in all languages, "HTML" is to remain
unchanged. When a standard attribute is available, there is no need for a custom data attribute to be used.
Every HTML element may have any number of custom data attributes specified, with any value.
- element .
dataset
-
Returns a
DOMStringMap
object for the element’sdata-*
attributes.Hyphenated names become camel-cased. For example,
data-foo-bar=""
becomeselement.dataset.fooBar
.
dataset
IDL attribute provides convenient
accessors for all the data-*
attributes on an element. On
getting, the dataset
IDL attribute must return a DOMStringMap
object, associated with the following algorithms, which expose these
attributes on their element:
-
The algorithm for getting the list of name-value pairs
-
-
Let list be an empty list of name-value pairs.
-
For each content attribute on the element whose first five characters are the string "
data-
" and whose remaining characters (if any) do not include any uppercase ASCII letters, in the order that those attributes are listed in the element’s attribute list, add a name-value pair to list whose name is the attribute’s name with the first five characters removed and whose value is the attribute’s value. -
For each name in list, for each U+002D HYPHEN-MINUS character (-) in the name that is followed by a lowercase ASCII letter, remove the U+002D HYPHEN-MINUS character (-) and replace the character that followed it by the same character converted to ASCII uppercase.
-
Return list.
-
-
The algorithm for setting names to certain values
-
-
Let name be the name passed to the algorithm.
-
Let value be the value passed to the algorithm.
-
If name contains a U+002D HYPHEN-MINUS character (-) followed by a lowercase ASCII letter, throw a "
SyntaxError
"DOMException
and abort these steps. -
For each uppercase ASCII letter in name, insert a U+002D HYPHEN-MINUS character (-) before the character and replace the character with the same character converted to ASCII lowercase.
-
Insert the string
data-
at the front of name. -
Set the value of the attribute with the name name, to the value value, replacing any previous value if the attribute already existed. If
setAttribute()
would have thrown an exception when setting an attribute with the name name, then this must throw the same exception.
-
-
The algorithm for deleting names
-
-
Let name be the name passed to the algorithm.
-
For each uppercase ASCII letter in name, insert a U+002D HYPHEN-MINUS character (-) before the character and replace the character with the same character converted to ASCII lowercase.
-
Insert the string
data-
at the front of name. -
Remove the attribute with the name name, if such an attribute exists. Do nothing otherwise.
This algorithm will only get invoked by the Web IDL specification for names that are given by the earlier algorithm for getting the list of name-value pairs. [WEBIDL]
-
class
attribute along with data-*
attributes:
<div class="spaceship" data-ship-id="30"> <button class="fire" onclick="spaceships[this.parentNode.dataset.shipId].fire()"> Fire </button> </div>
Notice how the hyphenated attribute name becomes camel-cased in the API.
Authors should carefully design such extensions so that when the attributes are ignored and any associated CSS dropped, the page is still usable.
JavaScript libraries may use the custom data attributes, as they are considered to be part of the page on which they are used. Authors of libraries that are reused by many authors are encouraged to include their name in the attribute names, to reduce the risk of clashes. Where it makes sense, library authors are also encouraged to make the exact name used in the attribute names customizable, so that libraries whose authors unknowingly picked the same name can be used on the same page, and so that multiple versions of a particular library can be used on the same page even when those versions are not mutually compatible.
data-doquery-range
, and a library called "jJo" could use attributes names like data-jjo-range
. The jJo library could also provide an API to set which prefix to
use (e.g., J.setDataPrefix("j2")
, making the attributes have names like data-j2-range
). 3.2.6. Requirements relating to the bidirectional algorithm
3.2.6.1. Authoring conformance criteria for bidirectional-algorithm formatting characters
Text content in html elements with Text
nodes in their contents,
and text in attributes of html elements that allow free-form text, may contain characters
in the ranges U+202A to U+202E and U+2066 to U+2069 (the bidirectional-algorithm formatting
characters). However, the use of these characters is restricted so that any embedding or overrides
generated by these characters do not start and end with different parent elements, and so that all
such embeddings and overrides are explicitly terminated by a U+202C POP DIRECTIONAL FORMATTING
character. This helps reduce incidences of text being reused in a manner that has unforeseen
effects on the bidirectional algorithm. [BIDI]
The aforementioned restrictions are defined by specifying that certain parts of documents form bidirectional-algorithm formatting character ranges, and then imposing a requirement on such ranges.
The strings resulting from applying the following algorithm to an HTML element element are bidirectional-algorithm formatting character ranges:
-
Let output be an empty list of strings.
-
Let string be an empty string.
-
Let node be the first child node of element, if any, or null otherwise.
-
Loop: If node is null, jump to the step labeled end.
-
Process node according to the first matching step from the following list:
- If node is a
Text
node - Append the text data of node to string.
- If node is a
br
element- If node is an HTML element that is flow content but that is not also phrasing content
- If string is not the empty string, push string onto output, and let string be empty string.
- Otherwise
- Do nothing.
- If node is a
-
Let node be node’s next sibling, if any, or null otherwise.
-
Jump to the step labeled loop.
-
End: If string is not the empty string, push string onto output.
-
Return output as the bidirectional-algorithm formatting character ranges.
The value of a namespace-less attribute of an HTML element is a bidirectional-algorithm formatting character range.
Any strings that, as described above, are bidirectional-algorithm formatting character ranges must match the string
production in the following ABNF, the character set for which is Unicode. [ABNF]
string = *( plaintext ( embedding / override / isolation ) ) plaintext embedding = ( lre / rle ) string pdf override = ( lro / rlo ) string pdf isolation = ( lri / rli / fsi ) string pdi lre = %x202A ; U+202A LEFT-TO-RIGHT EMBEDDING rle = %x202B ; U+202B RIGHT-TO-LEFT EMBEDDING lro = %x202D ; U+202D LEFT-TO-RIGHT OVERRIDE rlo = %x202E ; U+202E RIGHT-TO-LEFT OVERRIDE pdf = %x202C ; U+202C POP DIRECTIONAL FORMATTING lri = %x2066 ; U+2066 LEFT-TO-RIGHT ISOLATE rli = %x2067 ; U+2067 RIGHT-TO-LEFT ISOLATE fsi = %x2068 ; U+2068 FIRST STRONG ISOLATE pdi = %x2069 ; U+2069 POP DIRECTIONAL ISOLATE plaintext = *( %x0000-2029 / %x202F-2065 / %x206A-10FFFF ) ; any string with no bidirectional-algorithm formatting characters
While the U+2069 POP DIRECTIONAL ISOLATE character implicitly also ends open embeddings and overrides, text that relies on this implicit scope closure is not conforming to this specification. All strings of embeddings, overrides, and isolations need to be explicitly terminated to conform to this section’s requirements.
Authors are encouraged to use the dir
attribute, the bdo
element, and
the bdi
element, rather than maintaining the bidirectional-algorithm formatting
characters manually. The bidirectional-algorithm formatting characters interact poorly with CSS.
3.2.6.2. User agent conformance criteria
User agents must implement the Unicode bidirectional algorithm to determine the proper ordering of characters when rendering documents and parts of documents. [BIDI]
The mapping of HTML to the Unicode bidirectional algorithm must be done in one of three ways. Either the user agent must implement CSS, including in particular the CSS unicode-bidi, direction, and content properties, and must have, in its user agent style sheet, the rules using those properties given in this specification’s §10 Rendering section, or, alternatively, the user agent must act as if it implemented just the aforementioned properties and had a user agent style sheet that included all the aforementioned rules, but without letting style sheets specified in documents override them, or, alternatively, the user agent must implement another styling language with equivalent semantics. [CSS-WRITING-MODES-3] [CSS3-CONTENT]
The following elements and attributes have requirements defined by the §10 Rendering section that, due to the requirements in this section, are requirements on all user agents (not just those that support the suggested default rendering):
3.2.7. WAI-ARIA and HTML Accessibility API Mappings
3.2.7.1. ARIA Authoring Requirements
Authors may use the ARIArole
and aria-*
attributes on HTML elements, in accordance with the requirements described in the
ARIA specifications, except where these conflict with the requirements specified in
ARIA in HTML [html-aria]. These exceptions are intended to prevent authors from making assistive technology
products report nonsensical states that do not represent the actual state of the document. [WAI-ARIA]
In the majority of cases setting an ARIA role
and/or aria-*
attribute that matches the default implicit ARIA semantics is unnecessary and
not recommended as these properties are already set by the browser.
Authors are encouraged to make use of the following documents for guidance on using ARIA in HTML beyond that which is provided in this section:
- Notes on Using ARIA in HTML - A practical guide for developers on how to to add accessibility information to HTML elements using the Accessible Rich Internet Applications specification [WAI-ARIA].
- WAI-ARIA 1.1 Authoring Practices - An author’s guide to understanding and implementing Accessible Rich Internet Applications.
3.2.7.2. Conformance Checker Implementation Requirements
Conformance checkers are required to implement document conformance requirements for use of the
ARIA role
and aria-*
attributes on HTML elements , as defined in ARIA in HTML. [html-aria]
3.2.7.3. User Agent Implementation Requirements
User agents are required to implement ARIA semantics on all HTML elements , as defined in the ARIA specifications [WAI-ARIA] and [core-aam-1.1].
User agents are required to implement Accessibility API semantics on all HTML elements, as defined in the HTML Accessibility API Mappings specification [html-aam-1.0].
The ARIA attributes defined in the ARIA specifications do not have any effect on CSS pseudo-class matching, user interface modalities that don’t use assistive technologies, or the default actions of user interaction events as described in this specification.
3.2.7.3.1. ARIA Role Attribute
Every HTML element may have an ARIArole
attribute specified. This is an ARIA Role
attribute as defined by [WAI-ARIA].
The attribute, if specified, must have a value that is a set of space-separated tokens; each token must be a non-abstract role defined in the WAI-ARIA specification [WAI-ARIA].
role
attribute is split on spaces. 3.2.7.3.2. State and Property Attributes
Every HTML element may have ARIA state and property attributes specified. These attributes are defined by [WAI-ARIA].A subset of the ARIA State and Property attributes are defined as "Global States and Properties" in the [WAI-ARIA] Specification.
These attributes, if specified, must have a value that is the ARIA value type in the "Value" field of the definition for the state or property, mapped to the appropriate HTML value type according to [WAI-ARIA].
ARIA State and Property attributes can be used on any element. They are not always meaningful, however, and in such cases user agents might not perform any processing aside from including them in the DOM. State and property attributes are processed according to the requirements of the HTML Accessibility API Mappings specification [html-aam-1.0], as well as [WAI-ARIA] and , as defined in the ARIA specifications [WAI-ARIA] and [core-aam-1.1].
3.2.7.4. Allowed ARIA roles, states and properties
This section is non-normative.
The following table provides an informative reference to the ARIA roles, states and properties permitted for use in HTML. All ARIA roles, states and properties are normatively defined in the [WAI-ARIA] specification. Links to ARIA roles, states and properties in the table reference the normative [WAI-ARIA] definitions.
Role | Description | Required Properties | Supported Properties |
---|---|---|---|
any | ARIA global states and properties can be used on any HTML element. | none |
|
alert
| A message with important, and usually time-sensitive, information. See related alertdialog and status .
| none |
|
alertdialog
| A type of dialog that contains an alert message, where initial focus goes to an element
within the dialog. See related alert and dialog .
| none |
|
application
| A region declared as a web application, as opposed to a web document. | none |
|
article
| A section of a page that consists of a composition that forms an independent part of a document, page, or site. | none |
|
banner
| A region that contains mostly site-oriented content, rather than page-specific content. | none |
|
button
| An input that allows for user-triggered actions when clicked or pressed. See related link .
| none |
|
checkbox
| A checkable input that has three possible values: true, false, or mixed. |
| |
columnheader
| A cell containing header information for a column. | none |
|
combobox
| A presentation of a select; usually similar to a textbox where users can type ahead to
select an option, or type to enter arbitrary text as a new item in the list. See related listbox .
|
|
|
complementary
| A supporting section of the document, designed to be complementary to the main content at a similar level in the DOM hierarchy, but remains meaningful when separated from the main content. | none |
|
contentinfo
| A large perceivable region that contains information about the parent document. | none |
|
definition
| A definition of a term or concept. | none |
|
dialog
| A dialog is an application window that is designed to interrupt the current processing of
an application in order to prompt the user to enter information or require a response. See
related alertdialog .
| none |
|
directory
| A list of references to members of a group, such as a static table of contents. | none |
|
document
| A region containing related information that is declared as document content, as opposed to a web application. | none |
|
form
| A landmark region that contains a collection of items and objects that, as a whole,
combine to create a form. See related search .
| none |
|
grid
| A grid is an interactive control which contains cells of tabular data arranged in rows and columns, like a table. | none |
|
gridcell
| A cell in a grid or treegrid. | none |
|
group
| A set of user interface objects which are not intended to be included in a page summary or table of contents by assistive technologies. | none |
|
heading
| A heading for a section of the page. | none |
|
img
| A container for a collection of elements that form an image. | none |
|
link
| An interactive reference to an internal or external resource that, when activated, causes
the user agent to navigate to that resource. See related button .
| none |
|
list
| A group of non-interactive list items. See related listbox .
| none |
|
listbox
| A widget that allows the user to select one or more items from a list of choices. See
related combobox and list .
| none |
|
listitem
| A single item in a list or directory .
| none |
|
log
| A type of live region where new information is added in meaningful order and old
information may disappear. See related marquee .
| none |
|
main
| The main content of a document. | none |
|
marquee
| A type of live region where non-essential information changes frequently. See related log .
| none |
|
math
| Content that represents a mathematical expression. | none |
|
menu
| A type of widget that offers a list of choices to the user. | none |
|
menubar
| A presentation of menu that usually remains visible and is usually presented horizontally. | none |
|
menuitem
| An option in a group of choices contained by a menu or menubar .
| none | |
menuitemcheckbox
| A checkable menuitem that has three possible values: true, false, or mixed. |
| |
menuitemradio
| A checkable menuitem in a group of menuitemradio roles, only one of which can
be checked at a time.
|
|
|
navigation
| A collection of navigational elements (usually links) for navigating the document or related documents. | none |
|
note
| A section whose content is parenthetic or ancillary to the main content of the resource. | none |
|
option
| A selectable item in a select list. | none |
|
presentation
| An element whose implicit native role semantics will not be mapped to the accessibility API. | none | |
progressbar
| An element that displays the progress status for tasks that take a long time. | none |
|
radio
| A checkable input in a group of radio roles, only one of which can be checked at a time. |
|
|
radiogroup
| A group of radio buttons. | none |
|
region
| A large perceivable section of a web page or document, that the author feels is important enough to be included in a page summary or table of contents, for example, an area of the page containing live sporting event statistics. | none |
|
row
| A row of cells in a grid. | none |
|
rowgroup
| A group containing one or more row elements in a grid. | none |
|
rowheader
| A cell containing header information for a row in a grid. | none |
|
scrollbar
| A graphical object that controls the scrolling of content within a viewing area, regardless of whether the content is fully displayed within the viewing area. |
|
|
search
| A landmark region that contains a collection of items and objects that, as a whole,
combine to create a search facility. See related form .
| none |
|
separator
| A divider that separates and distinguishes sections of content or groups of menuitems. | none |
|
slider
| A user input where the user selects a value from within a given range. |
|
|
spinbutton
| A form of range that expects the user to select from among discrete choices. |
|
|
status
| A container whose content is advisory information for the user but is not important enough
to justify an alert, often but not necessarily presented as a status bar. See related alert .
| none |
|
tab
| A grouping label providing a mechanism for selecting the tab content that is to be rendered to the user. | none |
|
tablist
| A list of tab elements, which are references to tabpanel elements. | none |
|
tabpanel
| A container for the resources associated with a tab , where each tab is contained in a tablist .
| none |
|
textbox
| Input that allows free-form text as its value. | none |
|
timer
| A type of live region containing a numerical counter which indicates an amount of elapsed time from a start point, or the time remaining until an end point. | none |
|
toolbar
| A collection of commonly used function buttons represented in compact visual form. | none |
|
tooltip
| A contextual popup that displays a description for an element. | none |
|
tree
| A type of list that may contain sub-level nested groups that can be collapsed and expanded. | none |
|
treegrid
| A grid whose rows can be expanded and collapsed in the same manner as for a tree. | none |
|
treeitem
| An option item of a tree. This is an element within a tree that may be expanded or collapsed if it contains a sub-level group of treeitems. | none |
|
4. The elements of HTML
4.1. The root element
4.1.1. The html
element
- Categories:
- None.
- Contexts in which this element can be used:
- As the root element of a document.
- Wherever a subdocument fragment is allowed in a compound document.
- Content model:
- A
head
element followed by abody
element. - Tag omission in text/html:
- An
html
element’s start tag can be omitted if the first thing inside thehtml
element is not a comment.- An
html
element’s end tag can be omitted if thehtml
element is not immediately followed by a comment. - An
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLHtmlElement : HTMLElement {};
The html
element represents the root of an HTML document.
Authors are encouraged to specify a lang
attribute on the root html
element, giving
the document’s language. This aids speech synthesis tools to determine what pronunciations to use,
translation tools to determine what rules to use, and so forth.
It is recommended to keep the usage of attributes and their values defined on the html
element to a minimum to allow for proper detection of the character encoding declaration within the first 1024 bytes.
html
element in the following example declares that the document’s language is
English.
<!DOCTYPE html> <html lang="en"> <head> <title>Swapping Songs</title> </head> <body> <h1>Swapping Songs</h1> <p>Tonight I swapped some of the songs I wrote with some friends, who gave me some of the songs they wrote. I love sharing my music.</p> </body> </html>
4.2. Document metadata
4.2.1. The head
element
- Categories:
- None.
- Contexts in which this element can be used:
- As the first element in an
html
element. - Content model:
- If the document is an
iframe
srcdoc
document or if title information is available from a higher-level protocol: Zero or more elements of metadata content, of which no more than one is atitle
element and no more than one is abase
element.- Otherwise: One or more elements of metadata content, of which exactly one is a
title
element and no more than one is abase
element. - Otherwise: One or more elements of metadata content, of which exactly one is a
- Tag omission in text/html:
- A
head
element’s start tag may be omitted if the element is empty, or if the first thing inside thehead
element is an element.- A
head
element’s end tag may be omitted if thehead
element is not immediately followed by a space character or a comment. - A
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLHeadElement : HTMLElement {};
The head
element represents a collection of metadata for the Document
.
head
element can be large or small. Here is an
example of a very short one:
<!doctype html> <html> <head> <title>A document with a short head</title> </head> <body> ...
Here is an example of a longer one:
<!DOCTYPE HTML> <HTML> <HEAD> <META CHARSET="UTF-8"> <BASE HREF="https://www.example.com/"> <TITLE>An application with a long head</TITLE> <LINK REL="STYLESHEET" HREF="default.css"> <LINK REL="STYLESHEET ALTERNATE" HREF="big.css" TITLE="Big Text"> <SCRIPT SRC="support.js"></SCRIPT> <META NAME="APPLICATION-NAME" CONTENT="Long headed application"> </HEAD> <BODY> ...
The title
element is a required child in most situations, but when a higher-level
protocol provides title information, e.g., in the Subject line of an e-mail when HTML is used as
an e-mail authoring format, the title
element can be omitted.
It is recommended to keep the usage of attributes and their values defined on the head
element to a minimum to allow for proper detection of the character encoding declaration within the first 1024 bytes.
4.2.2. The title
element
- Categories:
- Metadata content.
- Contexts in which this element can be used:
- In a
head
element containing no othertitle
elements. - Content model:
- Text that is not inter-element whitespace.
- Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLTitleElement : HTMLElement { attribute DOMString text; };
The title
element represents the document’s title or name. Authors should use
titles that identify their documents even when they are used out of context, for example in a
user’s history or bookmarks, or in search results. The document’s title is often different from
its first heading, since the first heading does not have to stand alone when taken out of context.
There must be no more than one title
element per document.
If it’s reasonable for the Document
to have no title, then the title
element is probably not required. See the head
element’s content model for a
description of when the element is required.
- title .
text
[ = value ] -
Returns the contents of the element, ignoring child nodes that aren’t
Text
nodes.Can be set, to replace the element’s children with the given value.
text
must return a concatenation of the contents of
all the Text
nodes that are children of the title
element (ignoring
any other nodes such as comments or elements), in tree order. On setting, it must act the
same way as the textContent
IDL attribute. <title>Introduction to The Mating Rituals of Bees</title> ... <h1>Introduction</h1> <p>This companion guide to the highly successful <cite>Introduction to Medieval Bee-Keeping</cite> book is...
The next page might be a part of the same site. Note how the title describes the subject matter unambiguously, while the first heading assumes the reader knows what the context is and therefore won’t wonder if the dances are Salsa or Waltz:
<title>Dances used during bee mating rituals</title> ... <h2>The Dances</h2>
The string to use as the document’s title is given by the document.title
IDL
attribute.
title
element are used in this way, the directionality of that title
element should be used to set the
directionality of the document’s title in the user interface. 4.2.3. The base
element
- Categories:
- Metadata content.
- Contexts in which this element can be used:
- In a
head
element containing no otherbase
elements. - Content model:
- Nothing.
- Tag omission in text/html:
- No end tag.
- Content attributes:
- Global attributes
href
— Document base URLtarget
— Default browsing context for hyperlink navigation and §4.10.22 Form submission - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes.
- DOM interface:
-
interface HTMLBaseElement : HTMLElement { attribute DOMString href; attribute DOMString target; };
The base
element allows authors to specify the document base URL for the
purposes of parsing relative URLs, and the name of the default browsing context for the purposes of following hyperlinks. The element does not represent any content
beyond this information.
There must be no more than one base
element per document.
A base
element must have either an href
attribute, a target
attribute, or both.
The href
content attribute, if specified, must
contain a valid URL potentially surrounded by spaces.
A base
element, if it has an href
attribute, must come before any other elements in
the tree that have attributes defined as taking URLs except the html
element.
The target
attribute, if specified, must contain a valid browsing
context name or keyword, which specifies which browsing context is to be used as the
default when hyperlinks and forms in the Document
cause navigation.
A base
element, if it has a target
attribute, must come before any
elements in the tree that represent hyperlinks.
If there are multiple base
elements with target
attributes, all but
the first are ignored.
A base
element that is the first base
element with an href
content attribute in a particular Document
has a frozen base URL. The frozen base URL must be immediately set for an element whenever any of the following situations
occur:
-
The
base
element becomes the firstbase
element in tree order with anhref
content attribute in itsDocument
. -
The
base
element is the firstbase
element in tree order with anhref
content attribute in itsDocument
, and itshref
content attribute is changed.
To set the frozen base URL, for an element element:
-
Let document be element’s node document.
-
Let urlRecord be the result of parsing the value of element’s
href
content attribute with document’s fallback base URL, and document’s character encoding. (Thus thebase
element isn’t affected by itself.) -
Set elements’s frozen base URL to document’s fallback base URL, if urlRecord is failure or running Is base allowed for Document? on the resulting URL record and document returns "
Blocked
", and to urlRecord otherwise.
The href
IDL attribute, on getting, must
return the result of running the following algorithm:
-
Let document be element’s node document.
-
Let url be the value of the
href
attribute of thebase
element, if it has one, and the empty string otherwise. -
Let urlRecord be the result of parsing url with document’s fallback base url, and document’s character encoding. (Thus, the
base
element isn’t affected by otherbase
elements or itself). -
If urlRecord is failure, return url.
-
Return the serialization of urlRecord.
The href
IDL attribute, on setting, must set the href
content
attribute to the given new value.
The target
IDL attribute must reflect the content attribute of the same name.
base
element is used to set the document base URL:
<!DOCTYPE html> <html> <head> <title>This is an example for the <base> element</title> <base href="https://www.example.com/news/index.html"> </head> <body> <p>Visit the <a href="archives.html">archives</a>.</p> </body> </html>
The link in the above example would be a link to
"https://www.example.com/news/archives.html
".
4.2.4. The link
element
- Categories:
- Metadata content.
- Contexts in which this element can be used:
- Where metadata content is expected.
- In a
noscript
element that is a child of ahead
element. - In a
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag.
- Content attributes:
- Global attributes
href
— Address of the hyperlinkcrossorigin
— How the element handles crossorigin requestsrel
— Relationship of this document (or subsection/topic) to the destination resourcerev
— Reverse link relationship of the destination resource to this document (or subsection/topic)media
— Applicable mediahreflang
— Language of the linked resourcetype
— Hint for the type of the referenced resourcesizes
— Sizes of the icons (forrel
="icon
")- Also, the
title
attribute has special semantics on this element: Title of the link; alternative style sheet set name. - Allowed ARIA role attribute values:
link
(default - do not set).- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles.- For
role
value - Any
- DOM interface:
-
interface HTMLLinkElement : HTMLElement { attribute DOMString href; attribute DOMString? crossOrigin; attribute DOMString rel; attribute DOMString rev; [SameObject, PutForwards=value]readonly attribute DOMTokenList relList; attribute DOMString media; attribute DOMString hreflang; attribute DOMString type; [SameObject, PutForwards=value] readonly attribute DOMTokenList sizes; }; HTMLLinkElement implements LinkStyle;
The link
element allows authors to link their document to other resources.
The destination of the link(s) is given by the href
attribute, which must
be present and must contain a valid non-empty URL potentially surrounded by spaces. If the href
attribute is absent, then the element does not define
a link.
A link
element must have a rel
attribute.
If the rel
attribute is used, the element is restricted to the head
element.
The types of link indicated (the relationships) are given by the value of the rel
attribute, which, if present, must have a
value that is a set of space-separated tokens. The allowed keywords and their
meanings are defined in a later section. If the rel
attribute is absent, has no
keywords, or if none of the keywords used are allowed according to the definitions in this
specification, then the element does not create any links.
Two categories of links can be created using the link
element: Links to external resources and hyperlinks. The §4.8.6 Link types section defines
whether a particular link type is an external resource or a hyperlink. One link
element can create multiple links (of which some might be external resource links and some might
be hyperlinks); exactly which and how many links are created depends on the keywords given in the rel
attribute. User agents must process the links on a per-link
basis, not a per-element basis.
Each link created for a link
element is handled separately. For instance, if there
are two link
elements with rel="stylesheet"
, they each count as a
separate external resource, and each is affected by its own attributes independently. Similarly,
if a single link
element has a rel
attribute with the value next stylesheet
, it creates both a hyperlink (for the next
keyword) and an external resource link (for the stylesheet
keyword), and
they are affected by other attributes (such as media
or title
)
differently.
link
element creates two hyperlinks (to the same page):
<link rel="author license" href="/about">
The two links created by this element are one whose semantic is that the target page has information about the current page’s author, and one whose semantic is that the target page has information regarding the license under which the current page is provided.
link
and a
elements may also have a rev
attribute, which is used to describe
a reverse link relationship from the resource specified by the href
to the
current document. If present, the value of this attribute must be a set of space-separated
tokens. Like the rel
attribute, §4.8.6 Link types describes the allowed
keywords and their meanings for the rev
attribute. Both the rel
and rev
attributes may be present on the same element.
Reverse links are a way to express the reverse
directional relationship of a link. In contrast to the rel
attribute, whose value
conveys a forward directional relationship ("how is the link related to me"), the rev
attribute allows for similiar relationships to be expressed in the reverse direction ("how am I
related to this link"). These values can enable user agents to build a more comprehensive map of
linked documents.
rel
and rev
attributes as follows:
Document with URL "chapter1.html"
<link href="chapter2.html" rel="next" rev="prev">
Document with URL "chapter2.html"
<link href="chapter1.html" rel="prev" rev="next"> <link href="chapter3.html" rel="next" rev="prev">
From chapter1.html, the link to chapter2.html is the "next
" chapter in the series in the
forward direction, and the "previous
" chapter in the reverse diretion (from
chapter2.html to chapter1.html).
rel
and rev
as follows:
<ol> <li><a href="chapter1.html" rev="toc" rel="next">chapter 1</a></li> <li><a href="chapter2.html" rev="toc"></a>chapter 2</li> <li><a href="chapter3.html" rev="toc"></a>chapter 3</li> </ol>
From the table of contents, the "next
" logical path is to the first chapter,
expressed using rel
. Each chapter link has a "toc
" rev
value
which indicates that the current document is the table of contents document for every chapter.
The crossorigin
attribute is a CORS settings attribute. It is
intended for use with external resource links.
The exact behavior for links to external resources depends on the exact relationship, as defined for the relevant link type. Some of the attributes control whether or not the external resource is to be applied (as defined below).
For external resources that are represented in the DOM (for example, style sheets), the DOM representation must be made available (modulo cross-origin restrictions) even if the resource is not applied. To obtain the resource, the user agent must run the following steps:
-
If the
href
attribute’s value is the empty string, then abort these steps. -
Parse the URL given by the
href
attribute, relative to the element’s node document. If that fails, then abort these steps. Otherwise, let url be the resulting URL record. -
Let corsAttributeState be the current state of the element’s
crossorigin
content attribute. -
Let request be the result of creating a potential-CORS request given url and corsAttributeState.
-
Set request’s client to the
link
element’s node document’sWindow
object’s environment settings object. -
Fetch request.
User agents may opt to only try to obtain such resources when they are needed, instead of pro-actively fetching all the external resources that are not applied.
The semantics of the protocol used (e.g., HTTP) must be followed when fetching external resources. (For example, redirects will be followed and 404 responses will cause the external resource to not be applied.)
Once the attempts to obtain the resource and its critical subresources are complete, the
user agent must, if the loads were successful, queue a task to fire a simple event named load
at the link
element, or, if the resource or one of its critical subresources failed to completely load for any reason (e.g., DNS error, HTTP 404
response, a connection being prematurely closed, unsupported Content-Type), queue a task to fire a simple event named error
at the link
element.
Non-network errors in processing the resource or its subresources (e.g., CSS parse errors, PNG
decoding errors) are not failures for the purposes of this paragraph.
The task source for these tasks is the DOM manipulation task source.
The element must delay the load event of the element’s node document until all the attempts to obtain the resource and its critical subresources are complete. (Resources that the user agent has not yet attempted to obtain, e.g., because it is waiting for the resource to be needed, do not delay the load event.)
Interactive user agents may provide users with a means to follow the hyperlinks created
using the link
element, somewhere within their user interface. The exact interface
is not defined by this specification, but it could include the following information (obtained
from the element’s attributes, again as defined below), in some form or another (possibly
simplified), for each hyperlink created with each link
element in the document:
-
The relationship between this document and the resource (given by the
rel
attribute) -
The title of the resource (given by the
title
attribute). -
The address of the resource (given by the
href
attribute). -
The language of the resource (given by the
hreflang
attribute). -
The optimum media for the resource (given by the
media
attribute).
User agents could also include other information, such as the type of the resource (as given by
the type
attribute).
Hyperlinks created with the link
element and its rel
attribute apply
to the whole page. This contrasts with the rel
attribute of a
and area
elements, which indicates the type of a link whose context is given by the
link’s location within the document.
The media
attribute says which media the resource applies to. The value
must be a valid media query list.
media
attribute is purely advisory, and
describes for which media the document in question was designed.
However, if the link is an external resource link, then the media
attribute
is prescriptive. The user agent must apply the external resource when the media
attribute’s value matches the environment and the other relevant conditions apply, and
must not apply it otherwise.
The external resource might have further restrictions defined within that limit its
applicability. For example, a CSS style sheet might have some @media
blocks. This
specification does not override such further restrictions or requirements.
The default, if the media
attribute is omitted, is "all
", meaning that
by default links apply to all media.
The hreflang
attribute on the link
element has the same
semantics as the hreflang
attribute on the a
element.
The type
attribute gives the MIME type of the linked resource. It
is purely advisory. The value must be a valid mime type.
For external resource links, the type
attribute is used as a hint to user
agents so that they can avoid fetching resources they do not support. If the
attribute is present, then the user agent must assume that the resource is of the given type (even
if that is not a valid mime type, e.g., the empty string). If the attribute is omitted, but
the external resource link type has a default type defined, then the user agent must assume that
the resource is of that type. If the user agent does not support the given MIME type for the given
link relationship, then the user agent should not obtain the resource; if the user agent does support the
given MIME type for the given link relationship, then the user agent should obtain the
resource at the appropriate time as specified for the external resource link’s particular
type. If the attribute is omitted, and the external resource link type does not have a default
type defined, but the user agent would obtain the resource if the type was known and
supported, then the user agent should obtain the resource under the assumption that it will
be supported.
type
attribute authoritative — upon
fetching the resource, user agents must not use the type
attribute to determine its
actual type. Only the actual type (as defined in the next paragraph) is used to determine
whether to apply the resource, not the aforementioned assumed type.
If the external resource link type defines rules for processing the resource’s Content-Type metadata, then those rules apply. Otherwise, if the resource is expected to be an image, user agents may apply the image sniffing rules, with the official type being the type determined from the resource’s Content-Type metadata, and use the resulting computed type of the resource as if it was the actual type. Otherwise, if neither of these conditions apply or if the user agent opts not to apply the image sniffing rules, then the user agent must use the resource’s Content-Type metadata to determine the type of the resource. If there is no type metadata, but the external resource link type has a default type defined, then the user agent must assume that the resource is of that type.
The stylesheet
link type defines rules for processing the resource’s Content-Type metadata.
Once the user agent has established the type of the resource, the user agent must apply the resource if it is of a supported type and the other relevant conditions apply, and must ignore the resource otherwise.
<link rel="stylesheet" href="A" type="text/plain"> <link rel="stylesheet" href="B" type="text/css"> <link rel="stylesheet" href="C">
...then a compliant user agent that supported only CSS style sheets would fetch the B and C files, and
skip the A file (since text/plain
is not the MIME type for CSS style
sheets).
For files B and C, it would then check the actual types returned by the server. For those that
are sent as text/css
, it would apply the styles, but for those labeled as text/plain
, or any other type, it would not.
If one of the two files was returned without a Content-Type metadata, or with a
syntactically incorrect type like Content-Type: "null"
, then the default type
for stylesheet
links would kick in. Since that default type is text/css
, the style sheet would nonetheless be applied.
The title
attribute gives the title of the link. With one exception, it is
purely advisory. The value is text. The exception is for style sheet links, where the title
attribute defines alternative style sheet sets.
The title
attribute on link
elements differs from the global title
attribute of most other elements in that a link without a title does not
inherit the title of the parent element: it merely has no title.
The sizes
attribute is used with the icon
link type. The attribute must
not be specified on link
elements that do not have a rel
attribute that
specifies the icon
keyword.
link
elements that create hyperlinks is to
run the following steps:
-
If the
link
element’s node document is not fully active, then abort these steps. -
Follow the hyperlink created by the
link
element.
HTTP Link:
headers, if supported, must be assumed to come before any links in the
document, in the order that they were given in the HTTP message. These headers are to be
processed according to the rules given in the relevant specifications. [HTTP] [RFC5988]
Registration of relation types in HTTP Link: headers is distinct from HTML link types, and thus their semantics can be different from same-named HTML types.
The IDL attributes href
, rel
, rev
, media
, hreflang
, type
, and sizes
each must reflect the
respective content attributes of the same name.
The crossOrigin
IDL attribute must reflect the crossorigin
content attribute.
The IDL attribute relList
must reflect the rel
content attribute.
relList
’s DOMTokenList
’s supported tokens are the keywords
defined in HTML link types which are allowed on link
elements and supported
by the user agent.
rel
's supported tokens are the keywords defined in HTML link types which are allowed on link
elements, impact
the processing model, and are supported by the user agent. The possible supported tokens are alternate
, dns-prefetch, icon
, preconnect, prefetch, prerender, and stylesheet
. rel
's supported tokens must only include the tokens from
this list that the user agent implements the processing model for.
Other specifications may add HTML link types as
defined in Other link types, such as [RESOURCE-HINTS]. These specifications may require
that their link types be included in rel
's supported
tokens.
The LinkStyle
interface is also implemented by this element. [CSSOM]
link
elements provide some style sheets:
<!-- a persistent style sheet --> <link rel="stylesheet" href="default.css"> <!-- the preferred alternate style sheet --> <link rel="stylesheet" href="green.css" title="Green styles"> <!-- some alternate style sheets --> <link rel="alternate stylesheet" href="contrast.css" title="High contrast"> <link rel="alternate stylesheet" href="big.css" title="Big fonts"> <link rel="alternate stylesheet" href="wide.css" title="Wide screen">
<link rel=alternate href="/en/html" hreflang=en type=text/html title="English HTML"> <link rel=alternate href="/fr/html" hreflang=fr type=text/html title="French HTML"> <link rel=alternate href="/en/html/print" hreflang=en type=text/html media=print title="English HTML (for printing)"> <link rel=alternate href="/fr/html/print" hreflang=fr type=text/html media=print title="French HTML (for printing)"> <link rel=alternate href="/en/pdf" hreflang=en type=application/pdf title="English PDF"> <link rel=alternate href="/fr/pdf" hreflang=fr type=application/pdf title="French PDF">
4.2.5. The meta
element
- Categories:
- Metadata content.
- Contexts in which this element can be used:
- If the
charset
attribute is present, or if the element’shttp-equiv
attribute is in the encoding declaration state: in ahead
element.- If the
http-equiv
attribute is present but not in the encoding declaration state: in ahead
element.- If the
http-equiv
attribute is present but not in the encoding declaration state: in anoscript
element that is a child of ahead
element.- If the
name
attribute is present: where metadata content is expected. - If the
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag.
- Content attributes:
- Global attributes
name
— Metadata namehttp-equiv
— Pragma directivecontent
— Value of the elementcharset
— Character encoding declaration - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLMetaElement : HTMLElement { attribute DOMString name; attribute DOMString httpEquiv; attribute DOMString content; };
The meta
element represents various kinds of metadata that cannot be
expressed using the title
, base
, link
, style
,
and script
elements.
The meta
element can represent document-level metadata with the name
attribute, pragma directives with the http-equiv
attribute, and the file’s character encoding declaration when an HTML document is serialized to string form (e.g., for
transmission over the network or for disk storage) with the charset
attribute.
Exactly one of the name
, http-equiv
, and charset
attributes must be specified.
If either name
or http-equiv
is
specified, then the content
attribute must also be
specified. Otherwise, it must be omitted.
The charset
attribute specifies the character
encoding used by the document. This is a character encoding declaration. If the
attribute is present in an XML document, its value must be an ASCII case-insensitive match for the string "utf-8
" (and the
document is therefore forced to use UTF-8 as its encoding).
The charset
attribute on the meta
element has no effect in XML documents, and is only allowed in order to
facilitate migration to and from XHTML.
There must not be more than one meta
element with a charset
attribute
per document.
The content
attribute gives the value of the
document metadata or pragma directive when the element is used for those purposes. The allowed
values depend on the exact context, as described in subsequent sections of this specification.
If a meta
element has a name
attribute, it sets document metadata. Document metadata is expressed in terms of name-value pairs,
the name
attribute on the meta
element giving the
name, and the content
attribute on the same element giving
the value. The name specifies what aspect of metadata is being set; valid names and the meaning of
their values are described in the following sections. If a meta
element has no content
attribute, then the value part of the metadata name-value pair is the empty
string.
The name
and content
IDL attributes must reflect the respective content attributes of the same name. The IDL attribute httpEquiv
must reflect the content attribute http-equiv
.
4.2.5.1. Standard metadata names
This specification defines a few names for the name
attribute of the meta
element.
Names are case-insensitive, and must be compared in an ASCII case-insensitive manner.
-
The value must be a short free-form string giving the name of the Web application that the page represents. If the page is not a Web application, the
application-name
metadata name must not be used. Translations of the Web application’s name may be given, using thelang
attribute to specify the language of each name.There must not be more than one
meta
element with a given language and with itsname
attribute set to the valueapplication-name
per document.User agents may use the application name in UI in preference to the page’stitle
, since the title might include status messages and the like relevant to the status of the page at a particular moment in time instead of just being the name of the application.To find the application name to use given an ordered list of languages (e.g., British English, American English, and English), user agents must run the following steps:
-
Let languages be the list of languages.
-
Let default language be the language of the
Document
's root element, if any, and if that language is not unknown. -
If there is a default language, and if it is not the same language as any of the languages in languages, append it to languages.
-
Let winning language be the first language in languages for which there is a
meta
element in theDocument
that has itsname
attribute set to the valueapplication-name
and whose language is the language in question.If none of the languages have such a
meta
element, then abort these steps; there’s no given application name. -
Return the value of the
content
attribute of the firstmeta
element in theDocument
in tree order that has itsname
attribute set to the valueapplication-name
and whose language is winning language.
This algorithm would be used by a browser when it needs a name for the page, for instance, to label a bookmark. The languages it would provide to the algorithm would be the user’s preferred languages.
-
-
The value must be a free-form string giving the name of one of the page’s authors.
-
The value must be a free-form string that describes the page. The value must be appropriate for use in a directory of pages, e.g., in a search engine. There must not be more than one
meta
element with itsname
attribute set to the valuedescription
per document. -
The value must be a free-form string that identifies one of the software packages used to generate the document. This value must not be used on pages whose markup is not generated by software, e.g., pages whose markup was written by a user in a text editor.
Here is what a tool called "Frontweaver" could include in its output, in the page’shead
element, to identify itself as the tool used to generate the page:<meta name=generator content="Frontweaver 8.2">
-
The value must be a set of comma-separated tokens, each of which is a keyword relevant to the page.
This page about typefaces on British motorways uses ameta
element to specify some keywords that users might use to look for the page:<!DOCTYPE HTML> <html lang="en-GB"> <head> <title>Typefaces on UK motorways</title> <meta name="keywords" content="british,type face,font,fonts,highway,highways"> </head> <body> ...
Many search engines do not consider such keywords, because this feature has historically been used unreliably and even misleadingly as a way to spam search engine results in a way that is not helpful for users.
To obtain the list of keywords that the author has specified as applicable to the page, the user agent must run the following steps:-
Let keywords be an empty list.
-
For each
meta
element with aname
attribute and acontent
attribute and whosename
attribute’s value iskeywords
, run the following substeps:-
Split the value of the element’s
content
attribute on commas. -
Add the resulting tokens, if any, to keywords.
-
-
Remove any duplicates from keywords.
-
Return keywords. This is the list of keywords that the author has specified as applicable to the page.
User agents should not use this information when there is insufficient confidence in the reliability of the value.
For instance, it would be reasonable for a content management system to use the keyword information of pages within the system to populate the index of a site-specific search engine, but a large-scale content aggregator that used this information would likely find that certain users would try to game its ranking mechanism through the use of inappropriate keywords.
-
4.2.5.2. Other metadata names
Extensions to the predefined set of metadata names may be registered in the WHATWG Wiki MetaExtensions page. [WHATWGWIKI]
Anyone is free to edit the WHATWG Wiki MetaExtensions page at any time to add a type. These new names must be specified with the following information:
-
Keyword
-
The actual name being defined. The name should not be confusingly similar to any other defined name (e.g., differing only in case).
-
Brief description
-
A short non-normative description of what the metadata name’s meaning is, including the format the value is required to be in.
-
Specification
-
A link to a more detailed description of the metadata name’s semantics and requirements. It could be another page on the Wiki, or a link to an external page.
-
Synonyms
-
A list of other names that have exactly the same processing requirements. Authors should not use the names defined to be synonyms, they are only intended to allow user agents to support legacy content. Anyone may remove synonyms that are not used in practice; only names that need to be processed as synonyms for compatibility with legacy content are to be registered in this way.
-
Status
-
One of the following:
-
Proposed
-
The name has not received wide peer review and approval. Someone has proposed it and is, or soon will be, using it.
-
Ratified
-
The name has received wide peer review and approval. It has a specification that unambiguously defines how to handle pages that use the name, including when they use it in incorrect ways.
-
Discontinued
-
The metadata name has received wide peer review and it has been found wanting. Existing pages are using this metadata name, but new pages should avoid it. The "brief description" and "specification" entries will give details of what authors should use instead, if anything.
If a metadata name is found to be redundant with existing values, it should be removed and listed as a synonym for the existing value.
If a metadata name is registered in the "proposed" state for a period of a month or more without being used or specified, then it may be removed from the registry.
If a metadata name is added with the "proposed" status and found to be redundant with existing values, it should be removed and listed as a synonym for the existing value. If a metadata name is added with the "proposed" status and found to be harmful, then it should be changed to "discontinued" status.
Anyone can change the status at any time, but should only do so in accordance with the definitions above.
-
When an author uses a new metadata name not defined by either this specification or the Wiki page, conformance checkers should offer to add the value to the Wiki, with the details described above, with the "proposed" status.
Metadata names whose values are to be URLs must not be proposed or accepted. Links must be
represented using the link
element, not the meta
element.
4.2.5.3. Pragma directives
When the http-equiv
attribute is specified on a meta
element,
the element is a pragma directive.
The http-equiv
attribute is an enumerated attribute. The following table lists
the keywords defined for this attribute. The states given in the first cell of the rows with
keywords give the states to which those keywords map. Some of the keywords are
non-conforming, as noted in the last column.
State | Keyword | Notes |
---|---|---|
Content Language | content-language
| Non-conforming |
Encoding declaration | content-type
| |
Default style | default-style
| |
Refresh | refresh
| |
Cookie setter | set-cookie
| Non-conforming |
meta
element is inserted into the document, if its http-equiv
attribute is present and represents one of the above states, then the
user agent must run the algorithm appropriate for that state, as described in the following
list: -
Content language state (
http-equiv="content-language"
) -
This feature is non-conforming. Authors are encouraged to use the
lang
attribute instead.This pragma sets the pragma-set default language. Until such a pragma is successfully processed, there is no pragma-set default language.
-
If the
meta
element has nocontent
attribute, then abort these steps. -
If the element’s
content
attribute contains a U+002C COMMA character (,) then abort these steps. -
Let input be the value of the element’s
content
attribute. -
Let position point at the first character of input.
-
Collect a sequence of characters that are not space characters.
-
Let candidate be the string that resulted from the previous step.
-
If candidate is the empty string, abort these steps.
-
Set the pragma-set default language to candidate.
If the value consists of multiple space-separated tokens, tokens after the first are ignored.
This pragma is not the same as the HTTP
Content-Language
header of the same name. HTTPContent-Language
values with more than one language tag will be rejected as invalid by this pragma. [HTTP] -
-
Encoding declaration state (
http-equiv="content-type"
) -
The encoding declaration state is just an alternative form of setting the
charset
attribute: it is a character encoding declaration. This state’s user agent requirements are all handled by the parsing section of the specification.For
meta
elements with anhttp-equiv
attribute in the encoding declaration state, thecontent
attribute must have a value that is an ASCII case-insensitive match for a string that consists of: the literal string "text/html;
", optionally followed by any number of space characters, followed by the literal string "charset=
", followed by one of the labels of the character encoding of the character encoding declaration.A document must not contain both a
meta
element with anhttp-equiv
attribute in the encoding declaration state and ameta
element with thecharset
attribute present.The encoding declaration state may be used in HTML documents and in XML Documents. If the encoding declaration state is used in XML Documents, the name of the character encoding must be an ASCII case-insensitive match for the string "
UTF-8
" (and the document is therefore forced to use UTF-8 as its encoding).The encoding declaration state has no effect in XML documents, and is only allowed in order to facilitate migration to and from XHTML.
-
Default style state (
http-equiv="default-style"
) -
This pragma sets the name of the default alternative style sheet set.
-
If the
meta
element has nocontent
attribute, or if that attribute’s value is the empty string, then abort these steps. -
Set the preferred style sheet set to the value of the element’s
content
attribute. [CSSOM]
-
-
Refresh state (
http-equiv="refresh"
) -
This pragma acts as timed redirect.
-
If another
meta
element with anhttp-equiv
attribute in the Refresh state has already been successfully processed (i.e., when it was inserted the user agent processed it and reached the step labeled end), then abort these steps. -
If the
meta
element has nocontent
attribute, or if that attribute’s value is the empty string, then abort these steps. -
Let input be the value of the element’s
content
attribute. -
Let position point at the first character of input.
-
Collect a sequence of characters that are ASCII digits, and parse the resulting string using the rules for parsing non-negative integers. If the sequence of characters collected is the empty string, then no number will have been parsed; abort these steps. Otherwise, let time be the parsed number.
-
Collect a sequence of characters that are ASCII digits and U+002E FULL STOP characters (.). Ignore any collected characters.
-
Let url be the
meta
element’s node document’s URL. -
If position is past the end of input, jump to the step labeled end.
-
If the character in input pointed to by position is not a U+003B SEMICOLON character (;), a U+002C COMMA character (,), or a space character, then abort these steps.
-
If the character in input pointed to by position is a U+003B SEMICOLON character (;), a U+002C COMMA character (,), then advance position to the next character.
-
If position is past the end of input, jump to the step labeled end.
-
Let url be equal to the substring of input from the character at position to the end of the string.
-
If the character in input pointed to by position is a U+0055 LATIN CAPITAL LETTER U character (U) or a U+0075 LATIN SMALL LETTER U character (u), then advance position to the next character. Otherwise, jump to the step labeled skip quotes.
-
If the character in input pointed to by position is a U+0052 LATIN CAPITAL LETTER R character (R) or a U+0072 LATIN SMALL LETTER R character (r), then advance position to the next character. Otherwise, jump to the step labeled Parse.
-
If the character in input pointed to by position is s U+004C LATIN CAPITAL LETTER L character (L) or a U+006C LATIN SMALL LETTER L character (l), then advance position to the next character. Otherwise, jump to the step labeled Parse.
-
If the character in input pointed to by position is a U+003D EQUALS SIGN (=), then advance position to the next character. Otherwise, jump to the step step labeled Parse.
-
Skip quotes: If the character in input pointed to by position is either a U+0027 APOSTROPHE character (') or U+0022 QUOTATION MARK character ("), then let quote be that character, and advance position to the next character. Otherwise, let quote be the empty string.
-
Let url be equal to the substring of input from the character at position to the end of the string.
-
If quote is not the empty string, and there is a character in url equal to quote, then truncate url at that character, so that it and all subsequent characters are removed.
-
Parse: Parse url relative to the
meta
element’s node document. If that fails, abort these steps. Otherwise, let urlRecord be the resulting URL record. -
End: Perform one or more of the following steps:
-
After the refresh has come due (as defined below), if the user has not canceled the redirect and if the
meta
element’s node document’s active sandboxing flag set does not have the sandboxed automatic features browsing context flag set, navigate theDocument
's browsing context to urlRecord, with replacement enabled, and with theDocument
's browsing context as the source browsing context.For the purposes of the previous paragraph, a refresh is said to have come due as soon as the later of the following two conditions occurs:
-
At least time seconds have elapsed since the document has completely loaded, adjusted to take into account user or user agent preferences.
-
At least time seconds have elapsed since the
meta
element was inserted into the document, adjusted to take into account user or user agent preferences.
-
-
Provide the user with an interface that, when selected, navigates a browsing context to urlRecord, with the
Document
's browsing context as the source browsing context. -
Do nothing.
In addition, the user agent may, as with anything, inform the user of any and all aspects of its operation, including the state of any timers, the destinations of any timed redirects, and so forth.
-
For
meta
elements with anhttp-equiv
attribute in the Refresh state, thecontent
attribute must have a value consisting either of:-
just a valid non-negative integer, or
-
a valid non-negative integer, followed by a U+003B SEMICOLON character (;), followed by one or more space characters, followed by a substring that is an ASCII case-insensitive match for the string "
URL
", followed by a U+003D EQUALS SIGN character (=), followed by a valid URL that does not start with a literal U+0027 APOSTROPHE (') or U+0022 QUOTATION MARK (") character.
In the former case, the integer represents a number of seconds before the page is to be reloaded; in the latter case the integer represents a number of seconds before the page is to be replaced by the page at the given URL.
A news organization’s front page could include the following markup in the page’shead
element, to ensure that the page automatically reloads from the server every five minutes:<meta http-equiv="Refresh" content="300">
A sequence of pages could be used as an automated slide show by making each page refresh to the next page in the sequence, using markup such as the following:<meta http-equiv="Refresh" content="20; URL=page4.html">
-
Cookie setter (
http-equiv="set-cookie"
) -
This pragma sets an HTTP cookie. [COOKIES]
It is non-conforming. Real HTTP headers should be used instead.
-
If the
meta
element has nocontent
attribute, or if that attribute’s value is the empty string, then abort these steps. -
Act as if receiving a set-cookie-string for the document’s address via a "non-HTTP" API, consisting of the value of the element’s
content
attribute encoded as UTF-8. [COOKIES] [ENCODING]
-
-
Content security policy state (
http-equiv="content-security-policy"
) -
This pragma enforces a Content Security Policy on a
Document
. [CSP3]-
If the
meta
element is not a child of ahead
element, abort these steps. -
If the
meta
element has nocontent
attribute, or if that attribute’s value is the empty string, then abort these steps. -
Let policy be the result of executing Content Security Policy’s parse a serialized Content Security Policy algorithm on the
meta
element’scontent
attribute’s value. -
Remove all occurrences of the
report-uri
,frame-ancestors
, andsandbox
directives from policy. -
Enforce the policy policy.
For
meta
elements with anhttp-equiv
attribute in the Content security policy state, thecontent
attribute must have a value consisting of a valid Content Security Policy, but must not contain anyreport-uri
,frame-ancestors
, orsandbox
directives. The Content Security Policy given in thecontent
attribute will be enforced upon the current document. [CSP3] -
-
There must not be more than one meta
element with any particular state in the
document at a time.
4.2.5.4. Other pragma directives
Extensions to the predefined set of pragma directives may, under certain conditions, be registered in the WHATWG Wiki PragmaExtensions page. [WHATWGWIKI]
Such extensions must use a name that is identical to an HTTP header registered in the Permanent Message Header Field Registry, and must have behavior identical to that described for the HTTP header. [IANAPERMHEADERS]
Pragma directives corresponding to headers describing metadata, or not requiring specific user agent processing, must not be registered; instead, use metadata names. Pragma directives corresponding to headers that affect the HTTP processing model (e.g., caching) must not be registered, as they would result in HTTP-level behavior being different for user agents that implement HTML than for user agents that do not.
Anyone is free to edit the WHATWG Wiki PragmaExtensions page at any time to add a pragma directive satisfying these conditions. Such registrations must specify the following information:
-
Keyword
-
The actual name being defined. The name must match a previously-registered HTTP name with the same requirements.
-
Brief description
-
A short non-normative description of the purpose of the pragma directive.
-
Specification
-
A link to the specification defining the corresponding HTTP header.
4.2.5.5. Specifying the document’s character encoding
A character encoding declaration is a mechanism by which the character encoding used to store or transmit a document is specified.
The following restrictions apply to character encoding declarations:
-
The character encoding name given must be an ASCII case-insensitive match for one of the labels of the character encoding used to serialize the file. [ENCODING]
-
The character encoding declaration must be serialized without the use of character references or character escapes of any kind.
-
The element containing the character encoding declaration must be serialized completely within the first 1024 bytes of the document.
In addition, due to a number of restrictions on meta
elements, there can only be one meta
-based character encoding declaration per document.
If an HTML document does not start with a BOM, and its encoding is not explicitly
given by Content-Type metadata, and the document is not an iframe
srcdoc
document, then the character encoding used must be an ASCII-compatible encoding, and the encoding must be specified using a meta
element with a charset
attribute or a meta
element with an http-equiv
attribute in the encoding declaration state.
A character encoding declaration is required (either in the Content-Type metadata or explicitly in the file) even if the encoding is US-ASCII, because a character encoding is needed to process non-ASCII characters entered by the user in forms, in URLs generated by scripts, and so forth.
If the document is an iframe
srcdoc
document, the document must
not have a character encoding declaration. (In this case, the source is already decoded,
since it is part of the document that contained the iframe
.)
If an HTML document contains a meta
element with a charset
attribute or a meta
element with an http-equiv
attribute in the encoding declaration state, then the character encoding used must be an ASCII-compatible encoding.
Authors should use UTF-8. Conformance checkers may advise authors against using legacy encodings. [ENCODING]
Authoring tools should default to using UTF-8 for newly-created documents. [ENCODING]
Authors must not use encodings that are not defined in the WHATWG Encoding specification. Additionally, authors should not use ISO-2022-JP. [ENCODING]
Some encodings that are not defined in the WHATWG Encoding specification use bytes in the range 0x20 to 0x7E, inclusive, to encode characters other than the corresponding characters in the range U+0020 to U+007E, inclusive, and represent a potential security vulnerability: A user agent might end up interpreting supposedly benign plain text content as HTML tags and JavaScript.
Using non-UTF-8 encodings can have unexpected results on form submission and URL encodings, which use the document’s character encoding by default.
In XHTML, the XML declaration should be used for inline character encoding information, if necessary.
head
element):
<meta charset="utf-8">
In XML, the XML declaration would be used instead, at the very top of the markup:
<?xml version="1.0" encoding="utf-8"?>
4.2.6. The style
element
- Categories:
- Metadata content.
- Contexts in which this element can be used:
- Where metadata content is expected.
- In a
noscript
element that is a child of ahead
element. - In a
- Content model:
- Depends on the value of the
type
attribute, but must match requirements described in prose below. - Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
media
— Applicable medianonce
- Cryptographic nonce used in Content Security Policy checks [CSP3]type
— Type of embedded resource- Also, the
title
attribute has special semantics on this element: Alternative style sheet set name. - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLStyleElement : HTMLElement { attribute DOMString media; attribute DOMString nonce; attribute DOMString type; }; HTMLStyleElement implements LinkStyle;
There are no known native implementations of blocking the style
element based on CSP3 directives. Therefore this feature should not be relied upon.
The style
element allows authors to embed style information in their documents. The style
element is one of several inputs to the styling processing model. The element
does not represent content for the user.
The type
attribute gives the styling language. If the attribute is
present, its value must be a valid mime type that designates a styling language. The charset
parameter must not be specified. The default value for the type
attribute, which is used if the attribute is absent, is "text/css
". [RFC2318]
charset
parameter must be treated as an unknown parameter for the purpose of
comparing MIME types here. The media
attribute says which media the styles apply to. The value must
be a valid media query list. The user agent must apply the styles when
the media
attribute’s value matches the environment and the other relevant
conditions apply, and must not apply them otherwise.
The styles might be further limited in scope, e.g., in CSS with the use of @media
blocks. This specification does not override such further restrictions or requirements.
The default, if the media
attribute is omitted, is "all
", meaning that
by default styles apply to all media.
A style
element is restricted to
appearing in the head
of the document.
The nonce
attribute represents a cryptographic
nonce ("number used once") which can be used by Content Security Policy to determine
whether or not the style specified by an element will be applied to the document. The value is
text. [CSP3]
The title
attribute on style
elements defines alternative style sheet sets. If the style
element has no title
attribute, then it has no title; the title
attribute of ancestors does not apply to
the style
element. [CSSOM]
The title
attribute on style
elements, like the title
attribute on link
elements, differs from the global title
attribute in
that a style
block without a title does not inherit the title of the parent
element: it merely has no title.
The textContent
of a style
element must match the style
production in the following ABNF, the character set for which is Unicode. [ABNF]
style = no-c-start *( c-start no-c-end c-end no-c-start ) no-c-start = < any string that doesn’t contain a substring that matches c-start > c-start = "<!--" no-c-end = < any string that doesn’t contain a substring that matches c-end > c-end = "-->"
style
block algorithm that
applies for the style sheet language specified by the style
element’s type
attribute, passing it the element’s style data, whenever one of the following
conditions occur:
-
the element is popped off the stack of open elements of an HTML parser or XML parser,
-
the element is not on the stack of open elements of an HTML parser or XML parser, and it is inserted into a document or removed from a document,
-
the element is not on the stack of open elements of an HTML parser or XML parser, and one of its child nodes is modified by a script,
For styling languages that consist of pure text (as opposed to XML), a style
element’s style data is the concatenation of the contents of all the Text
nodes that are children of the style
element (not any other nodes such as comments
or elements), in tree order. For XML-based styling languages, the style data consists of all the child nodes of the style
element.
The update a style
block algorithm for CSS (text/css
) is as
follows:
-
Let element be the
style
element. -
If element has an associated CSS style sheet, remove the CSS style sheet in question.
-
If element is not in a
Document
, then abort these steps. -
If the Should element’s inline behavior be blocked by Content Security Policy? algorithm returns "
Blocked
" when executed upon thestyle
element, "style
", and thestyle
element’s style data, then abort these steps. [CSP3] -
create a CSS style sheet with the following properties:
-
text/css
-
element
-
The
media
attribute of element.This is a reference to the (possibly absent at this time) attribute, rather than a copy of the attribute’s current value. The CSSOM specification defines what happens when the attribute is dynamically set, changed, or removed.
-
The
title
attribute of element.Again, this is a reference to the attribute.
-
Unset.
-
Set.
-
-
null
-
Left at its default value.
-
Left uninitialized.
This specification does not define any other styling language’s update a style
block algorithm.
Once the attempts to obtain the style sheet’s critical subresources, if any, are
complete, or, if the style sheet has no critical subresources, once the style sheet has
been parsed and processed, the user agent must, if the loads were successful or there were none, queue a task to fire a simple event named load
at the style
element, or, if one of the style sheet’s critical subresources failed
to completely load for any reason (e.g., DNS error, HTTP 404 response, a connection being
prematurely closed, unsupported Content-Type), queue a task to fire a simple event named error
at the style
element. Non-network errors in processing the
style sheet or its subresources (e.g., CSS parse errors, PNG decoding errors) are not failures
for the purposes of this paragraph.
The task source for these tasks is the DOM manipulation task source.
The element must delay the load event of the element’s node document until all the attempts to obtain the style sheet’s critical subresources, if any, are complete.
This specification does not specify a style system, but CSS is expected to be supported by most Web browsers. [CSS-2015]
media
, nonce
, and type
IDL attributes must reflect the respective content
attributes of the same name. The LinkStyle
interface is also implemented by this element. [CSSOM]
<!DOCTYPE html><html> <head> <title>My favorite book</title> <style> body { color: black; background: white; } em { font-style: normal; color: red; } </style> </head> <body> <p>My <em>favorite</em> book of all time has <em>got</em> to be <cite>A Cat’s Life</cite>. It is a book by P. Rahmel that talks about the <i lang="la">Felis Catus</i> in modern human society.</p> </body> </html>
4.2.7. Interactions of styling and scripting
Style sheets, whether added by a link
element, a style
element, an <?xml-stylesheet?>
PI, an HTTP Link
header, or some other
mechanism, have a style sheet ready flag, which is initially unset.
When a style sheet is ready to be applied, its style sheet ready flag must be set. If the
style sheet referenced no other resources (e.g., it was an internal style sheet given by a style
element with no @import
rules), then the style rules must be immediately made available to script; otherwise, the style rules must only be made
available to script once the event loop reaches its update the rendering step.
A style sheet in the context of the Document
of an HTML parser or XML parser is
said to be a style sheet that is blocking scripts if the element was created by that Document
's parser, and the element is either a style
element or a link
element that
was an external resource link when the element was created by
the parser, and the element’s style sheet was enabled when the element was created by the parser,
and the element’s style sheet ready flag is not yet set, and, the last time the event loop reached step 1, the element was in that Document
, and the user
agent hasn’t given up on that particular style sheet yet. A user agent may give up on a style
sheet at any time.
Giving up on a style sheet before the style sheet loads, if the style sheet eventually does still load, means that the script might end up operating with incorrect information. For example, if a style sheet sets the color of an element to green, but a script that inspects the resulting style is executed before the sheet is loaded, the script will find that the element is black (or whatever the default color is), and might thus make poor choices (e.g., deciding to use black as the color elsewhere on the page, instead of green). Implementors have to balance the likelihood of a script using incorrect information with the performance impact of doing nothing while waiting for a slow network request to finish.
A Document
has a style sheet that is blocking scripts if there is either a style sheet that is blocking scripts in the context of that Document
, or
if that Document
is in a browsing context that has a parent browsing context, and the active document of that parent browsing context itself has a style sheet that is blocking scripts.
A Document
has no style sheet that is blocking scripts if it does not have a style sheet that is blocking scripts as defined in the previous paragraph.
4.3. Sections
4.3.1. The body
element
- Categories:
- Sectioning root.
- Contexts in which this element can be used:
- As the second element in an
html
element. - Content model:
- Flow content.
- Tag omission in text/html:
- A
body
element’s start tag may be omitted if the element is empty, or if the first thing inside thebody
element is not a space character or a comment, except if the first thing inside thebody
element is ameta
,link
,script
,style
, ortemplate
element.- A
body
element’s end tag may be omitted if thebody
element is not immediately followed by a comment. - A
- Content attributes:
- Global attributes
onafterprint
onbeforeprint
onbeforeunload
onhashchange
onlanguagechange
onmessage
onoffline
ononline
onpagehide
onpageshow
onpopstate
onrejectionhandled
onstorage
onunhandledrejection
onunload
- Allowed ARIA role attribute values:
-
document
role (default - do not set),application
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLBodyElement : HTMLElement { }; HTMLBodyElement implements WindowEventHandlers;
The body
element represents the content of the document.
In conforming documents, there is only one body
element. The document.body
IDL attribute provides scripts with easy access to a document’s body
element.
Some DOM operations (for example, parts of the drag and drop model) are defined in terms
of "the body
element". This refers to a particular element in the DOM, as per the
definition of the term, and not any arbitrary body
element.
The body
element exposes as event handler content attributes a number of the event handlers of the Window
object. It also mirrors their event handler IDL attributes.
The onblur
, onerror
, onfocus
, onload
, onresize
, and onscroll
event handlers of the Window
object, exposed on the body
element, replace the generic event handlers with
the same names normally supported by html elements.
Thus, for example, a bubbling error
event dispatched on a child of the body
element of a Document
would first trigger the onerror
event handler content attributes of that element, then that of the root html
element, and only then would it trigger the onerror
event handler
content attribute on the body
element. This is because the event would bubble
from the target, to the body
, to the html
, to the Document
, to the Window
, and the event handler on the body
is watching the Window
not the body
. A regular event
listener attached to the body
using addEventListener()
, however, would
be run when the event bubbled through the body
and not when it reaches the Window
object.
<!DOCTYPE HTML> <html> <head> <title>Online or offline?</title> <script> function update(online) { document.getElementById('status').textContent = online ? 'Online' : 'Offline'; } </script> </head> <body ononline="update(true)" onoffline="update(false)" onload="update(navigator.onLine)"> <p>You are: <span id="status">(Unknown)</span></p> </body> </html>
4.3.2. The article
element
- Categories:
- Flow content, but with no
main
element descendants.- Sectioning content.
- Palpable content.
- Sectioning content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
article
(default - do not set),application
,document
ormain
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The article
element represents a complete, or self-contained, composition in a document,
page, application, or site. This could be a magazine, newspaper, technical or
scholarly article, an essay or report, a blog or other social media post.
A general rule is that the article
element is appropriate only if the element’s
contents would be listed explicitly in the document’s outline. Each article
should be
identified, typically by including a heading(h1
-h6
element) as a child of the article
element.
Assistive Technology may convey the semantics of the article
to users. This
information can provide a hint to users as to the type of content. For example the role
of
the element, which in this case matches the element name "article", can be announced by
screen reader software when a user navigates to an article
element. User Agents
may also provide methods to navigate to article
elements.
When article
elements are nested, the inner article
elements represent
articles that are in principle related to the contents of the outer article. For instance, a blog
entry on a site could consist of summaries of other blog entries in article
elements nested
within the article
element for the blog entry.
Author information associated with an article
element (q.v. the address
element) does not apply to nested article
elements.
The following is an example of a blog post extract, marked up using the article
element:
<article> <header> <h2><a href="https://herbert.io">Short note on wearing shorts</a></h2> <p>Posted on Wednesday, 10 February 2016 by Patrick Lauke. <a href="https://herbert.io/short-note/#comments">6 comments</a></p> </header> <p>A fellow traveller posed an interesting question: Why do you wear shorts rather than longs? The person was wearing culottes as the time, so I considered the question equivocal in nature, but I attempted to provide an honest answer despite the dubiousness of the questioner’s dress.</p> <p>The short answer is that I enjoy wearing shorts, the long answer is...</p> <p><a href="https://herbert.io/short-note/">Continue reading: Short note on wearing shorts</a></p> </article>
The schema.org vocabulary can be used to provide more granular information about the type of article, using the CreativeWork - Article subtypes, other information such as the publication date for the article can also be provided.
This example shows a blog post using the article
element, with some schema.org
annotations:
<article itemscope itemtype="https://schema.org/BlogPosting"> <header> <h2 itemprop="headline">The Very First Rule of Life</h2> <p><time itemprop="datePublished" datetime="2016-02-28">3 days ago</time></p> </header> <p>If there’s a microphone anywhere near you, assume it’s hot and sending whatever you’re saying to the world. Seriously.</p> <p>...</p> <footer> <a itemprop="discussionUrl" href="?comments=1">Show comments...</a> </footer> </article>
Here is that same blog post, but showing some of the comments:
<article itemscope itemtype="https://schema.org/BlogPosting"> <header> <h2 itemprop="headline">The Very First Rule of Life</h2> <p><time itemprop="datePublished" datetime="2009-10-09">3 days ago</time></p> </header> <p>If there’s a microphone anywhere near you, assume it’s hot and sending whatever you’re saying to the world. Seriously.</p> <p>...</p> <section> <h3>Comments</h3> <ol> <li itemprop="comment" itemscope itemtype="https://schema.org/UserComments" id="c1"> <p>Posted by: <span itemprop="creator" itemscope itemtype="https://schema.org/Person"> <span itemprop="name">George Washington</span> </span></p> <p><time itemprop="commentTime" datetime="2009-10-10">15 minutes ago</time></p> <p>Yeah! Especially when talking about your lobbyist friends!</p> <li itemprop="comment" itemscope itemtype="https://schema.org/UserComments" id="c2"> <p>Posted by: <span itemprop="creator" itemscope itemtype="https://schema.org/Person"> <span itemprop="name">George Hammond</span> </span></p> <p><time itemprop="commentTime" datetime="2009-10-10">5 minutes ago</time></p> <p>Hey, you have the same first name as me.</p> </li> </ol> </section> </article>
Notice the use of an ordered list ol
to organize the comments. Also note the
comments are a subsection of the article, identified using a section
element.
4.3.3. The section
element
- Categories:
- Flow content.
- Sectioning content.
- Palpable content.
- Sectioning content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
region
role (default - do not set),alert
,alertdialog
,application
,contentinfo
,dialog
,document
,log
,main
,marquee
,presentation
,search
orstatus
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The section element represents a generic section of a document or application.
A section, in this context, is a thematic grouping of content. Each section
should be
identified, typically by including a heading (h1
-h6
element) as a child
of the section element.
Examples of sections would be chapters, the various tabbed pages in a tabbed dialog box, or the numbered sections of a thesis. A Web site’s home page could be split into sections for an introduction, news items, and contact information.
Authors are encouraged to use the article
element instead of the section
element when the content is complete, or self-contained, composition.
The section
element is not a generic container element. When an element is needed
only for styling purposes or as a convenience for scripting, authors are encouraged to use the div
element instead. A general rule is that the section
element is
appropriate only if the element’s contents would be listed explicitly in the document’s outline.
Assistive Technology may convey the semantics of the section
to users when
the element has an explicit label. This information can provide a hint to users as to the type of content.
For example the role
of the element, which in this case is "region",
can be announced by screen reader software when a user navigates to an section
element. User Agents
may also provide methods to navigate to section
elements.
The section
has an aria-label
attribute providing a brief description of
the contents. Assistive technology may convey the region
role
along with the aria-label
value as a hint to users.
<article> <header> <h2>Apples</h2> <p>Tasty, delicious fruit!</p> </header> <p>The apple is the pomaceous fruit of the apple tree.</p> <section aria-label="Red apples."> <h3>Red Delicious</h3> <p>These bright red apples are the most common found in many supermarkets.</p> </section> <section aria-label="Green apples."> <h3>Granny Smith</h3> <p>These juicy, green apples make a great filling for apple pies.</p> </section> </article>
<!DOCTYPE Html> <html ><head ><title >Graduation Ceremony Summer 2022</title ></head ><body ><h1 >Graduation</h1 ><section ><h2 >Ceremony</h2 ><p >Opening Procession</p ><p >Speech by Validactorian</p ><p >Speech by Class President</p ><p >Presentation of Diplomas</p ><p >Closing Speech by Headmaster</p ></section ><section ><h2 >Graduates</h2 ><ul ><li >Molly Carpenter</li ><li >Anastasia Luccio</li ><li >Ebenezar McCoy</li ><li >Karrin Murphy</li ><li >Thomas Raith</li ><li >Susan Rodriguez</li ></ul ></section ></body ></html>
article
element as part of an even larger document containing other
books.
<style> section { border: double medium; margin: 2em; } section.chapter h3 { font: 2em Roboto, Helvetica Neue, sans-serif; } section.appendix h3 { font: small-caps 2em Roboto, Helvetica Neue, sans-serif; } </style> ... <article class="book"> <header> <h2>My Book</h2> <p>A sample with not much content</p> <p><small>Published by Dummy Publicorp Ltd.</small></p> </header> <section class="chapter"> <h3>My First Chapter</h3> <p>This is the first of my chapters. It doesn’t say much.</p> <p>But it has two paragraphs!</p> </section> <section class="chapter"> <h3>It Continues: The Second Chapter</h3> <p>Bla dee bla, dee bla dee bla. Boom.</p> </section> <section class="chapter"> <h3>Chapter Three: A Further Example</h3> <p>It’s not like a battle between brightness and earthtones would go unnoticed.</p> <p>But it might ruin my story.</p> </section> <section class="appendix"> <h3>Appendix A: Overview of Examples</h3> <p>These are demonstrations.</p> </section> <section class="appendix"> <h3>Appendix B: Some Closing Remarks</h3> <p>Hopefully this long example shows that you <em>can</em> style sections, so long as they are used to indicate actual sections.</p> </section> </article>
4.3.4. The nav
element
- Categories:
- Flow content.
- Sectioning content.
- Palpable content.
- Sectioning content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content, but with no
main
element descendants. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
navigation
role (default - do not set) orpresentation
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The nav
element represents a section of a page that links to other pages or to
parts within the page: a section with navigation links.
Assistive Technology may convey the semantics of the nav
to users.
This information can provide a hint to users as to the type of content. For example the role
of the element, which in this case is "navigation", can be announced by screen reader software when a
user navigates to an nav
element. User Agents may also provide methods to navigate to nav
elements.
In cases where the content of a nav
element represents a list of items, use list
markup to aid understanding and navigation.
Not all groups of links on a page need to be in a nav
element — the element is
primarily intended for sections that consist of major navigation blocks. In particular, it is
common for footers to have a short list of links to various pages of a site, such as the terms
of service, the home page, and a copyright page. The footer
element alone is
sufficient for such cases; while a nav
element can be used in such cases, it is
usually unnecessary.
User agents (such as screen readers) that are targeted at users who can benefit from navigation information being omitted in the initial rendering, or who can benefit from navigation information being immediately available, can use this element as a way to determine what content on the page to initially skip or provide on request (or both).
nav
elements, one for primary navigation
around the site, and one for secondary navigation around the page itself.
<body> <h1>The Wiki Center Of Exampland</h1> <nav> <ul> <li><a href="/">Home</a></li> <li><a href="/events">Current Events</a></li> ...more... </ul> </nav> <article> <header> <h2>Demos in Exampland</h2> <p>Written by A. N. Other.</p> </header> <nav> <ul> <li><a href="#public">Public demonstrations</a></li> <li><a href="#destroy">Demolitions</a></li> ...more... </ul> </nav> <div> <section id="public"> <h2>Public demonstrations</h2> <p>...more...</p> </section> <section id="destroy"> <h2>Demolitions</h2> <p>...more...</p> </section> ...more... </div> <footer> <p><a href="?edit">Edit</a> | <a href="?delete">Delete</a> | <a href="?Rename">Rename</a></p> </footer> </article> <footer> <p><small>© copyright 1998 Exampland Emperor</small></p> </footer> </body>
<body typeof="schema:Blog"> <header> <h1>Wake up sheeple!</h1> <p><a href="news.html">News</a> - <a href="blog.html">Blog</a> - <a href="forums.html">Forums</a></p> <p>Last Modified: <span property="schema:dateModified">2009-04-01</span></p> <nav> <h2>Navigation</h2> <ul> <li><a href="articles.html">Index of all articles</a></li> <li><a href="today.html">Things sheeple need to wake up for today</a></li> <li><a href="successes.html">Sheeple we have managed to wake</a></li> </ul> </nav> </header> <main> <article property="schema:blogPosts" typeof="schema:BlogPosting"> <header> <h2 property="schema:headline">My Day at the Beach</h2> </header> <main property="schema:articleBody"> <p>Today I went to the beach and had a lot of fun.</p> ...more content... </main> <footer> <p>Posted <time property="schema:datePublished" datetime="2009-10-10">Thursday</time>.</p> </footer> </article> ...more blog posts... </main> <footer> <p>Copyright © <span property="schema:copyrightYear">2010</span> <span property="schema:copyrightHolder">The Example Company</span> </p> <p><a href="about.html">About</a> - <a href="policy.html">Privacy Policy</a> - <a href="contact.html">Contact Us</a></p> </footer> </body>
Notice the main
element being used to wrap the main content of the page. In this
case, all content other than the page header and footer.
You can also see microdata annotations in the above example that use the schema.org vocabulary to provide the publication date and other metadata about the blog post.
nav
element doesn’t have to contain a list, it can contain other kinds of content
as well. In this navigation block, links are provided in prose:
<nav> <h2>Navigation</h2> <p>You are on my home page. To the north lies <a href="/blog">my blog</a>, from whence the sounds of battle can be heard. To the east you can see a large mountain, upon which many <a href="/school">school papers</a> are littered. Far up thus mountain you can spy a little figure who appears to be me, desperately scribbling a <a href="/school/thesis">thesis</a>.</p> <p>To the west are several exits. One fun-looking exit is labeled <a href="https://games.example.com/">"games"</a>. Another more boring-looking exit is labeled <a href="https://isp.example.net/">ISP™</a>.</p> <p>To the south lies a dark and dank <a href="/about">contacts page</a>. Cobwebs cover its disused entrance, and at one point you see a rat run quickly out of the page.</p> </nav>
nav
is used in an e-mail application, to let the user switch
folders:
<p><input type=button value="Compose" onclick="compose()"></p> <nav> <h2>Folders</h2> <ul> <li> <a href="/inbox" onclick="return openFolder(this.href)">Inbox</a> <span class=count></span> <li> <a href="/sent" onclick="return openFolder(this.href)">Sent</a> <li> <a href="/drafts" onclick="return openFolder(this.href)">Drafts</a> <li> <a href="/trash" onclick="return openFolder(this.href)">Trash</a> <li> <a href="/customers" onclick="return openFolder(this.href)">Customers</a> </ul> </nav>
4.3.5. The aside
element
- Categories:
- Flow content.
- Sectioning content.
- Palpable content.
- Sectioning content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content, but with no
main
element descendants. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
complementary
role (default - do not set),note
,search
orpresentation
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The aside
element represents a section of a page that consists of content that
is tangentially related to the content of the parenting sectioning content, and which
could be considered separate from that content. Such sections are often represented as sidebars
in printed typography.
The element can be used for typographical effects like pull quotes or sidebars, for advertising,
for groups of nav
elements, and for other content that is considered separate from
the main content of the nearest ancestor sectioning content.
Assistive Technology may convey the semantics of the aside
to users. This
information can provide a hint to users as to the type of content. For example the role
of
the element, which in this case is "complementary", can be announced by screen reader software when a user
navigates to an aside
element. User Agents may also provide methods to navigate to aside
elements.
It’s not appropriate to use the aside
element just for parentheticals, since those
are part of the main flow of the document.
<aside> <h2>Switzerland</h2> <p>Switzerland, a land-locked country in the middle of geographic Europe, has not joined the geopolitical European Union, though it is a signatory to a number of European treaties.</p> </aside>
... <p>He later joined a large company, continuing on the same work. <q>I love my job. People ask me what I do for fun when I’m not at work. But I’m paid to do my hobby, so I never know what to answer. Some people wonder what they would do if they didn’t have to work... but I know what I would do, because I was unemployed for a year, and I filled that time doing exactly what I do now.</q></p> <aside> <q> People ask me what I do for fun when I’m not at work. But I’m paid to do my hobby, so I never know what to answer. </q> </aside> <p>Of course his work — or should that be hobby? —isn’t his only passion. He also enjoys other pleasures.</p> ...
aside
can be used for blogrolls and other side
content on a blog:
<body> <header> <h1>My wonderful blog</h1> <p>My tagline</p> </header> <aside> <!-- this aside contains two sections that are tangentially related to the page, namely, links to other blogs, and links to blog posts from this blog --> <nav> <h2>My blogroll</h2> <ul> <li><a href="https://blog.example.com/">Example Blog</a> </ul> </nav> <nav> <h2>Archives</h2> <ol reversed> <li><a href="/last-post">My last post</a> <li><a href="/first-post">My first post</a> </ol> </nav> </aside> <aside> <!-- this aside is tangentially related to the page also, it contains twitter messages from the blog author --> <h2>Twitter Feed</h2> <blockquote cite="https://twitter.example.net/t31351234"> I’m on vacation, writing my blog. </blockquote> <blockquote cite="https://twitter.example.net/t31219752"> I’m going to go on vacation soon. </blockquote> </aside> <article> <!-- this is a blog post --> <h2>My last post</h2> <p>This is my last post.</p> <footer> <p><a href="/last-post" rel=bookmark>Permalink</a> </footer> </article> <article> <!-- this is also a blog post --> <h2>My first post</h2> <p>This is my first post.</p> <aside> <!-- this aside is about the blog post, since it’s inside the <article> element; it would be wrong, for instance, to put the blogroll here, since the blogroll isn’t really related to this post specifically, only to the page as a whole --> <h1>Posting</h1> <p>While I’m thinking about it, I wanted to say something about posting. Posting is fun!</p> </aside> <footer> <p><a href="/first-post" rel=bookmark>Permalink</a> </footer> </article> <footer> <nav> <a href="/archives">Archives</a> —<a href="/about">About me</a> — <a href="/copyright">Copyright</a> </nav> </footer> </body>
4.3.6. The h1
, h2
, h3
, h4
, h5
, and h6
elements
- Categories:
- Flow content.
- Heading content.
- Palpable content.
- Heading content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
heading
role (default - do not set),tab
orpresentation
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLHeadingElement : HTMLElement {};
These elements represent headings for their sections.
These elements have a rank given by the number in their name. The h1
element has the highest rank, the h6
element has the lowest rank, and two
elements with the same name have equal rank.
Use the rank of heading elements to create the document outline.
<body> <h1>top level heading</h1> <section><h2>2nd level heading</h2> <section><h3>3nd level heading</h3> <section><h4>4th level heading</h4> <section><h5>5th level heading</h5> <section><h6>6th level heading</h6> </section> </section> </section> </section> </section> </body>
The document outline would be the same if the section
elements were not used.
h2
–h6
elements must not be used to markup subheadings, subtitles,
alternative titles and taglines unless intended to be the heading for a new section or subsection.
Instead use the markup patterns in the §4.13 Common idioms without dedicated elements section of
the specification.
Assistive technology often announces the presence and level of a heading to users, as a hint
to understand the structure of a document and construct a 'mental model' of its outline. For example
the role
of the element, which in this case is "heading" and the heading level "1" to "6", can be
announced by screen reader software when a user navigates to an h1
–h6
element.
User Agents may also provide methods to navigate to h1
–h6
elements.
<body> <h1>Let’s call it a draw(ing surface)</h1> <h2>Diving in</h2> <h2>Simple shapes</h2> <h2>Canvas coordinates</h2> <h3>Canvas coordinates diagram</h3> <h2>Paths</h2> </body>
<body> <h1>Let’s call it a draw(ing surface)</h1> <section> <h2>Diving in</h2> </section> <section> <h2>Simple shapes</h2> </section> <section> <h2>Canvas coordinates</h2> <section> <h3>Canvas coordinates diagram</h3> </section> </section> <section> <h2>Paths</h2> </section> </body>
Authors might prefer the former style for its terseness, or the latter style for its convenience in the face of heavy editing; which is best is purely an issue of preferred authoring style.
The two styles can be combined, for compatibility with legacy tools while still future-proofing for when that compatibility is no longer needed.
The semantics and meaning of the h1
–h6
elements are further
detailed in the section on §4.3.10 Headings and sections.
4.3.7. The header
element
- Categories:
- Flow content.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content, but with no
main
element descendants, orheader
,footer
elements that are not descendants of sectioning content which is a descendant of theheader
. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
banner
role (default - do not set) orpresentation
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The header
element represents introductory content for its nearest ancestor sectioning content or sectioning root element. A header
typically
contains a group of introductory or navigational aids.
When the nearest ancestor sectioning content or sectioning root element is the body
element, then it applies to the whole page.
A header
element is intended to usually contain the section’s heading (an h1
–h6
element), but this is not required. The header
element can also be used to wrap a section’s table of contents, a search form, or any relevant
logos.
Assistive Technology may convey the semantics of the header
to users when the
nearest ancestor sectioning content or sectioning root element is the body
element.
This information can provide a hint to users as to the type of content. For example the role
of the element, which in this case is "banner", can be announced by screen reader software when a
user navigates to an header
element that is scoped to the body
element. User Agents may
also provide methods to navigate to header
elements scoped to the body
element.
<header> <p>Welcome to...</p> <h1>Voidwars!</h1> </header>
The following snippet shows how the element can be used to mark up a specification’s header:
<header> <h1>Scalable Vector Graphics (SVG) 1.2</h1> <p>W3C Working Draft 27 October 2004</p> <dl> <dt>This version:</dt> <dd><a href="https://www.w3.org/TR/2004/WD-SVG12-20041027/">https://www.w3.org/TR/2004/WD-SVG12-20041027/</a></dd> <dt>Previous version:</dt> <dd><a href="https://www.w3.org/TR/2004/WD-SVG12-20040510/">https://www.w3.org/TR/2004/WD-SVG12-20040510/</a></dd> <dt>Latest version of SVG 1.2:</dt> <dd><a href="https://www.w3.org/TR/SVG12/">https://www.w3.org/TR/SVG12/</a></dd> <dt>Latest SVG Recommendation:</dt> <dd><a href="https://www.w3.org/TR/SVG/">https://www.w3.org/TR/SVG/</a></dd> <dt>Editor:</dt> <dd>Dean Jackson, W3C, <a href="mailto:dean@w3.org">dean@w3.org</a></dd> <dt>Authors:</dt> <dd>See <a href="#authors">Author List</a></dd> </dl> <p class="copyright"><a href="https://www.w3.org/Consortium/Legal/ipr-notic ... </header>
The header
element is not sectioning content; it doesn’t introduce a new
section.
h1
element, and two
subsections whose headings are given by h2
elements. The content after the header
element is still part of the last subsection started in the header
element, because the header
element doesn’t take part in the outline algorithm.
<body> <header> <h1>Little Green Guys With Guns</h1> <nav> <ul> <li><a href="/games">Games</a> <li><a href="/forum">Forum</a> <li><a href="/download">Download</a> </ul> </nav> <h2>Important News</h2> <!-- this starts a second subsection --> <!-- this is part of the subsection entitled "Important News" --> <p>To play today’s games you will need to update your client.</p> <h2>Games</h2> <!-- this starts a third subsection --> </header> <p>You have three active games:</p> <!-- this is still part of the subsection entitled "Games" --> ...
For cases where an developer wants to nest a header
or footer
within
another header
: The header
element can only contain a header
or footer
if they are themselves contained within sectioning content.
In this example, the article
has a header
which contains an aside
which itself contains a header
. This is conforming as the descendant header
is contained
within the aside
element.
<article> <header> <h1>Flexbox: The definitive guide</h1> <aside> <header> <h2>About the author: Wes McSilly</h2> <p><a href="./wes-mcsilly/">Contact him! (Why would you?)</a></p> </header> <p>Expert in nothing but Flexbox. Talented circus sideshow.</p> </aside> </header> <p><ins>The guide about Flexbox was supposed to be here, but it turned out Wes wasn’t a Flexbox expert either.</ins></p> </article>
4.3.8. The footer
element
- Categories:
- Flow content.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content, but with no
main
element descendants, orheader
,footer
elements that are not descendants of sectioning content which is a descendant of thefooter
. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
contentinfo
role (default - do not set) orpresentation
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The footer
element represents a footer for its nearest ancestor sectioning content or sectioning root element. A footer typically contains
information about its section such as who wrote it, links to related documents, copyright data,
and the like.
When the footer
element contains entire sections, they represent appendices,
indexes, long colophons, verbose license agreements, and other such content.
Assistive Technology may convey the semantics of the footer
to users when the
nearest ancestor sectioning content or sectioning root element is the body
element.
This information can provide a hint to users as to the type of content. For example the role
of the element, which in this case is "content information", can be announced by screen reader software when a
user navigates to an footer
element that is scoped to the body
element. User Agents may
also provide methods to navigate to footer
elements scoped to the body
element.
Contact information for the author or editor of a section belongs in an address
element, possibly itself inside a footer
. Bylines and other information that could
be suitable for both a header
or a footer
can be placed in either (or
neither). The primary purpose of these elements is merely to help the author write
self-explanatory markup that is easy to maintain and style; they are not intended to impose
specific structures on authors.
Footers don’t necessarily have to appear at the end of a section, though they usually do.
When the nearest ancestor sectioning content or sectioning root element is the body
element, then it applies to the whole page.
The footer
element is not sectioning content; it doesn’t introduce a new
section.
<body> <footer><a href="../">Back to index...</a></footer> <div> <h1>Lorem ipsum</h1> <p>The ipsum of all lorems</p> </div> <p>A dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p> <footer><a href="../">Back to index...</a></footer> </body>
footer
element being used both for a site-wide
footer and for a section footer.
<!DOCTYPE HTML> <HTML><HEAD> <TITLE>The Ramblings of a Scientist</TITLE> <BODY> <h1>The Ramblings of a Scientist</h1> <MAIN> <ARTICLE> <H2>Episode 15</H2> <VIDEO SRC="/fm/015.ogv" CONTROLS PRELOAD> <P><A HREF="/fm/015.ogv">Download video</A>.</P> </VIDEO> <FOOTER> <!-- footer for article --> <P>Published <TIME DATETIME="2009-10-21T18:26-07:00">on 2009/10/21 at 6:26pm</TIME></P> </FOOTER> </ARTICLE> <ARTICLE> <H2>My Favorite Trains</H2> <P>I love my trains. My favorite train of all time is a Köf.</P> <P>It is fun to see them pull some coal cars because they look so dwarfed in comparison.</P> <FOOTER> <!-- footer for article --> <P>Published <TIME DATETIME="2009-09-15T14:54-07:00">on 2009/09/15 at 2:54pm</TIME></P> </FOOTER> </ARTICLE> </MAIN> <FOOTER> <!-- site wide footer --> <NAV> <P><A HREF="/credits.html">Credits</A> —<A HREF="/tos.html">Terms of Service</A> — <A HREF="/index.html">Blog Index</A></P> </NAV> <P>Copyright © 2009 Gordon Freeman</P> </FOOTER> </BODY> </HTML>
This fragment shows the bottom of a page on a site with a "fat footer":
... <footer> <nav> <section> <h2>Articles</h2> <p><img src="images/somersaults.jpeg" alt=""> Go to the gym with our somersaults class! Our teacher Jim takes you through the paces in this two-part article. <a href="articles/somersaults/1">Part 1</a> · <a href="articles/somersaults/2">Part 2</a></p> <p><img src="images/kindplus.jpeg"> Tired of walking on the edge of a clif<!-- sic -->? Our guest writer Lara shows you how to bumble your way through the bars. <a href="articles/kindplus/1">Read more...</a></p> <p><img src="images/crisps.jpeg"> The chips are down, now all that’s left is a potato. What can you do with it? <a href="articles/crisps/1">Read more...</a></p> </section> <ul> <li> <a href="/about">About us...</a> <li> <a href="/feedback">Send feedback!</a> <li> <a href="/sitemap">Sitemap</a> </ul> </nav> <p><small>Copyright © 2015 The Snacker —<a href="/tos">Terms of Service</a></small></p> </footer> </body>
4.3.9. The address
element
- Categories:
- Flow content.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content, but with no heading
content descendants, no sectioning content descendants, and no
header
,footer
, oraddress
element descendants. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
contentinfo
role.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The address
element represents the contact information for its nearest article
or body
element ancestor. If that is the body
element,
then the contact information applies to the document as a whole.
<ADDRESS> <A href="../People/Raggett/">Dave Raggett</A>, <A href="../People/Arnaud/">Arnaud Le Hors</A>, contact persons for the <A href="Activity">W3C HTML Activity</A> </ADDRESS>
The address
element must not be used to represent arbitrary addresses (e.g., postal
addresses), unless those addresses are in fact the relevant contact information. (The p
element is the appropriate element for marking up postal addresses in general.)
The address
element must not contain information other than contact information.
address
element:
<ADDRESS>Last Modified: 1999/12/24 23:37:50</ADDRESS>
Typically, the address
element would be included along with other information in a footer
element.
address
elements defined by the first applicable entry from the following list:
- If node is an
article
element- If node is a
body
element - If node is a
- The contact information consists of all the
address
elements that have node as an ancestor and do not have anotherbody
orarticle
element ancestor that is a descendant of node. - If node has an ancestor element that is an
article
element- If node has an ancestor element that is a
body
element - If node has an ancestor element that is a
- The contact information of node is the same as the contact information of the
nearest
article
orbody
element ancestor, whichever is nearest. - If node’s node document has a
body
element - The contact information of node is the same as the contact information of the
body
element of theDocument
. - Otherwise
- There is no contact information for node.
User agents may expose the contact information of a node to the user, or use it for other purposes, such as indexing sections based on the sections' contact information.
<footer> <address> For more details, contact <a href="mailto:js@example.com">John Smith</a>. </address> <p><small>© copyright 2038 Example Corp.</small></p> </footer>
4.3.10. Headings and sections
The h1
–h6
elements are headings.
The first element of heading content in an element of sectioning content represents the heading for that section. Subsequent headings of equal or higher rank start new (implied) sections, headings of lower rank start implied subsections that are part of the previous one. In both cases, the element represents the heading of the implied section.
h1
–h6
elements must not be used to markup subheadings, subtitles,
alternative titles and taglines unless intended to be the heading for a new section or subsection.
Instead use the markup patterns in the §4.13 Common idioms without dedicated elements section of
the specification.
Certain elements are said to be sectioning roots, including blockquote
and td
elements. These elements can have their own outlines, but the sections and
headings inside these elements do not contribute to the outlines of their ancestors.
Sectioning content elements are always considered subsections of their nearest ancestor sectioning root or their nearest ancestor element of sectioning content, whichever is nearest, regardless of what implied sections other headings may have created.
<body> <h1>Foo</h1> <h2>Bar</h2> <blockquote> <h3>Bla</h3> </blockquote> <p>Baz</p> <h2>Quux</h2> <section> <h3>Thud</h3> </section> <p>Grunt</p> </body>
...the structure would be:
-
Foo (heading of explicit
body
section, containing the "Grunt" paragraph)-
Bar (heading starting implied section, containing a block quote and the "Baz" paragraph)
-
Quux (heading starting implied section with no content other than the heading itself)
-
Thud (heading of explicit
section
section)
-
Notice how the section
ends the earlier implicit section so that a later paragraph
("Grunt") is back at the top level.
Sections may contain headings of a rank equal to their section nesting level. Authors should use headings of the appropriate rank for the section’s nesting level.
Authors are also encouraged to explicitly wrap sections in elements of sectioning content, instead of relying on the implicit sections generated by having multiple headings in one element of sectioning content.
<body> <h1>Apples</h1> <p>Apples are fruit.</p> <section> <h2>Taste</h2> <p>They taste lovely.</p> <h3>Sweet</h3> <p>Red apples are sweeter than green ones.</p> <h3>Color</h3> <p>Apples come in various colors.</p> </section> </body>
However, the same document would be more clearly expressed as:
<body> <h1>Apples</h1> <p>Apples are fruit.</p> <section> <h2>Taste</h2> <p>They taste lovely.</p> <section> <h3>Sweet</h3> <p>Red apples are sweeter than green ones.</p> </section> </section> <section> <h3>Color</h3> <p>Apples come in various colors.</p> </section> </body>
Both of the documents above are semantically identical and would produce the same outline in compliant user agents.
4.3.10.1. Creating an outline
There are currently no known native implementations of the outline algorithm in graphical browsers or
assistive technology user agents, although the algorithm is implemented in other software such
as conformance checkers and browser extensions. Therefore the outline algorithm
cannot be relied upon to convey document structure to users. Authors should use heading rank (h1
-h6
) to convey document structure.
This section is non-normative
The outline for a sectioning content element or a sectioning root element consists of a list of one or more potentially nested sections. The element for which an outline is created is said to be the outline’s owner.
A section is a container that corresponds to some nodes in the original DOM tree. Each section can have one heading associated with it, and can contain any number of further nested sections. The algorithm for the outline also associates each node in the DOM tree with a particular section and potentially a heading. (The sections in the outline aren’t section elements, though some may correspond to such elements — they are merely conceptual sections.)
<body> <h1>A</h1> <p>B</p> <h2>C</h2> <p>D</p> <h2>E</h2> <p>F</p> </body>
...results in the following outline being created for the body
node (and thus the
entire document):
-
Section created for
body
node. Associated with heading "A". Also associated with paragraph "B". Nested sections:-
Section implied for first
h2
element. Associated with heading "C". Also associated with paragraph "D". No nested sections. -
Section implied for second
h2
element. Associated with heading "E". Also associated with paragraph "F". No nested sections.
-
-
Let current outline target be null. (It holds the element whose outline is being created.)
-
Let current section be null. (It holds a pointer to a section, so that elements in the DOM can all be associated with a section.)
-
Create a stack to hold elements, which is used to handle nesting. Initialize this stack to empty.
-
Walk over the DOM in tree order, starting with the sectioning content element or sectioning root element at the root of the subtree for which an outline is to be created, and trigger the first relevant step below for each element as the walk enters and exits it.
- When exiting an element, if that element is the element at the top of the stack
-
The element being exited is a heading content element or an element with a
hidden
attribute.Pop that element from the stack.
- If the top of the stack is a heading content element or an element with a
hidden
attribute - Do nothing.
- When entering an element with a
hidden
attribute - Push the element being entered onto the stack. (This causes the algorithm to skip that element and any descendants of the element.)
- When entering a sectioning content element
-
Run these steps:
-
If current outline target is not null, run these substeps:
-
If the current section has no heading, create an implied heading and let that be the heading for the current section.
-
Push current outline target onto the stack.
-
-
Let current outline target be the element that is being entered.
-
Let current section be a newly created section for the current outline target element.
-
Associate current outline target with current section.
-
Let there be a new outline for the new current outline target, initialized with just the new current section as the only section in the outline.
-
- When exiting a sectioning content element, if the stack is not empty
-
Run these steps:
-
If the current section has no heading, create an implied heading and let that be the heading for the current section.
-
Pop the top element from the stack, and let the current outline target be that element.
-
Let current section be the last section in the outline of the current outline target element.
-
Append the outline of the sectioning content element being exited to the current section. (This does not change which section is the last section in the outline.)
-
- When entering a sectioning root element
-
Run these steps:
-
If current outline target is not null, push current outline target onto the stack.
-
Let current outline target be the element that is being entered.
-
Let current outline target’s parent section be current section.
-
Let current section be a newly created section for the current outline target element.
-
Let there be a new outline for the new current outline target, initialized with just the new current section as the only section in the outline.
-
- When exiting a sectioning root element, if the stack is not empty
-
Run these steps:
-
If the current section has no heading, create an implied heading and let that be the heading for the current section.
-
Let current section be current outline target’s parent section.
-
Pop the top element from the stack, and let the current outline target be that element.
-
- When exiting a sectioning content element or a sectioning root element (when the stack is empty)
-
The current outline target is the element being exited, and it is the sectioning content element or a sectioning root element at the root of the subtree for which an outline is being generated.
If the current section has no heading, create an implied heading and let that be the heading for the current section.
Skip to the next step in the overall set of steps. (The walk is over.)
- When entering a heading content element
-
If the current section has no heading, let the element being entered be the
heading for the current section.
Otherwise, if the element being entered has a rank equal to or higher than the heading of the last section of the outline of the current outline target, or if the heading of the last section of the outline of the current outline target is an implied heading, then create a new section and append it to the outline of the current outline target element, so that this new section is the new last section of that outline. Let current section be that new section. Let the element being entered be the new heading for the current section.
Otherwise, run these substeps:
-
Let candidate section be current section.
-
Heading loop: If the element being entered has a rank lower than the rank of the heading of the candidate section, then create a new section, and append it to candidate section. (This does not change which section is the last section in the outline.) Let current section be this new section. Let the element being entered be the new heading for the current section. Abort these substeps.
-
Let new candidate section be the section that contains candidate section in the outline of current outline target.
-
Let candidate section be new candidate section.
-
Return to the step labeled heading loop.
Push the element being entered onto the stack. (This causes the algorithm to skip any descendants of the element.)
Recall that
h1
has the highest rank, andh6
has the lowest rank. -
- Otherwise
- Do nothing.
In addition, whenever the walk exits a node, after doing the steps above, if the node is not associated with a section yet, associate the node with the section current section.
-
Associate all non-element nodes that are in the subtree for which an outline is being created with the section with which their parent element is associated.
-
Associate all nodes in the subtree with the heading of the section with which they are associated, if any.
The tree of sections created by the algorithm above, or a proper subset thereof, must be used when generating document outlines, for example when generating tables of contents.
The outline created for the body
element of a Document
is the outline of the entire document.
When creating an interactive table of contents, entries should jump the user to the relevant sectioning content element, if the section was created for a real element in the original document, or to the relevant heading content element, if the section in the tree was generated for a heading in the above process.
Selecting the first section of the document therefore always takes the user to the top
of the document, regardless of where the first heading in the body
is to be
found.
The outline depth of a heading content element associated with a section section is the number of sections that are ancestors of section in the outermost outline that section finds itself in when
the outlines of its Document
's elements are created, plus 1. The outline depth of a heading content element not associated with a section is 1.
User agents should provide default headings for sections that do not have explicit section headings.
<body> <nav> <p><a href="/">Home</a></p> </nav> <p>Hello world.</p> <aside> <p>My cat is cute.</p> </aside> </body>
Although it contains no headings, this snippet has three sections: a document (the body
) with two subsections (a nav
and an aside
). A user
agent could present the outline as follows:
-
Untitled document
-
Navigation
-
Sidebar
-
These default headings ("Untitled document", "Navigation", "Sidebar") are not specified by this specification, and might vary with the user’s language, the page’s language, the user’s preferences, the user agent implementor’s preferences, etc.
function (root, enter, exit) { var node = root; start: while (node) { enter(node); if (node.firstChild) { node = node.firstChild; continue start; } while (node) { exit(node); if (node == root) { node = null; } else if (node.nextSibling) { node = node.nextSibling; continue start; } else { node = node.parentNode; } } } }
4.3.11. Usage summary
This section is non-normative.
Element | Purpose |
---|---|
Example | |
body
| |
<!DOCTYPE HTML> <html> <head> <title>Steve Hill’s Home Page</title> </head> <body> <p>Hard Trance is My Life.</p> </body> </html> | |
article
| |
<article> <img src="/tumblr_masqy2s5yn1rzfqbpo1_500.jpg" alt="Yellow smiley face with the caption 'masif'"> <p>My fave Masif tee so far!</p> <footer>Posted 2 days ago</footer> </article> <article> <img src="/tumblr_m9tf6wSr6W1rzfqbpo1_500.jpg" alt=""> <p>Happy 2nd birthday Masif Saturdays!!!</p> <footer>Posted 3 weeks ago</footer> </article> | |
section
| |
<h1>Biography</h1> <section> <h1>The facts</h1> <p>1500+ shows, 14+ countries</p> </section> <section> <h1>2010/2011 figures per year</h1> <p>100+ shows, 8+ countries</p> </section> | |
nav
| |
<nav> <ul> <li><a href="/">Home</a> <li><a href="/biog.html">Bio</a> <li><a href="/discog.html">Discog</a> </ul> </nav> | |
aside
| |
<h1>Music</h1> <p>As any burner can tell you, the event has a lot of trance.</p> <aside>You can buy the music we played at our <a href="buy.html">playlist page</a>.</aside> <p>This year we played a kind of trance that originated in Belgium, Germany, and the Netherlands in the mid 90s.</p> | |
h1 –h6
| A section heading |
<h1>The Guide To Music On The Playa</h1> <h2>The Main Stage</h2> <p>If you want to play on a stage, you should bring one.</p> <h2>Amplified Music</h2> <p>Amplifiers up to 300W or 90dB are welcome.</p> | |
header
| |
<article> <header> <h1>Hard Trance is My Life</h1> <p>By DJ Steve Hill and Technikal</p> </header> <p>The album with the amusing punctuation has red artwork.</p> </article> | |
footer
| |
<article> <h1>Hard Trance is My Life</h1> <p>The album with the amusing punctuation has red artwork.</p> <footer> <p>Artists: DJ Steve Hill and Technikal</p> </footer> </article> | |
address
| |
<address> To book DJ Steve Hill and Technikal, contact our <a href="mailto:management@example.com">management</a>. </address> |
4.3.11.1. Article or section?
This section is non-normative.
A section
forms part of something else. An article
is its own thing. But
how does one know which is which? Mostly the real answer is "it depends on author intent".
For example, one could imagine a book with a "Granny Smith" chapter that just said "These juicy,
green apples make a great filling for apple pies."; that would be a section
because
there’d be lots of other chapters on (maybe) other kinds of apples.
On the other hand, one could imagine a tweet or tumblr post or newspaper
classified ad that just said "Granny Smith. These juicy, green apples make a great filling for
apple pies."; it would then be article
s because that was the whole thing.
Comments on an article are not part of the article
on which they are commenting, but are
related, therefore may be contained in their own nested article
.
4.4. Grouping content
4.4.1. The p
element
- Categories:
- Flow content.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- A
p
element’s end tag may be omitted if thep
element is immediately followed by anaddress
,article
,aside
,blockquote
,details
,div
,dl
,fieldset
,figcaption
,figure
,footer
,form
,h1
,h2
,h3
,h4
,h5
,h6
,header
,hr
,main
,menu
,nav
,ol
,p
,pre
,section
,table
, orul
, element, or if there is no more content in the parent element and the parent element is an HTML element that is not ana
,audio
,del
,ins
,map
,noscript
, orvideo
element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLParagraphElement : HTMLElement {};
The p
element represents a paragraph.
While paragraphs are usually represented in visual media by blocks of text that are physically separated from adjacent blocks through blank lines, a style sheet or user agent would be equally justified in presenting paragraph breaks in a different manner, for instance using inline pilcrows (¶).
<p>The little kitten gently seated itself on a piece of carpet. Later in his life, this would be referred to as the time the cat sat on the mat.</p>
<fieldset> <legend>Personal information</legend> <p> <label>Name: <input name="n"></label> <label><input name="anon" type="checkbox"> Hide from other users</label> </p> <p><label>Address: <textarea name="a"></textarea></label></p> </fieldset>
<p>There was once an example from Femley,<br> Whose markup was of dubious quality.<br> The validator complained,<br> So the author was pained,<br> To move the error from the markup to the rhyming.</p>
The p
element should not be used when a more specific element is more appropriate.
<section> <!-- ... --> <p>Last modified: 2001-04-23</p> <p>Author: fred@example.com</p> </section>
However, it would be better marked-up as:
<section> <!-- ... --> <footer>Last modified: 2001-04-23</footer> <address>Author: fred@example.com</address> </section>
Or:
<section> <!-- ... --> <footer> <p>Last modified: 2001-04-23</p> <address>Author: fred@example.com</address> </footer> </section>
ol
and ul
elements) cannot be children
of p
elements. When a sentence contains a bulleted list, therefore, one might
wonder how it should be marked up.
-
wizards,
-
faster-than-light travel, and
-
telepathy,
and is further discussed below.
The solution is to realize that a paragraph, in HTML terms, is not a logical concept, but a structural one. In the fantastic example above, there are actually five paragraphs as defined by this specification: one before the list, one for each bullet, and one after the list.
<p>For instance, this fantastic sentence has bullets relating to</p> <ul> <li>wizards, <li>faster-than-light travel, and <li>telepathy, </ul> <p>and is further discussed below.</p>
Authors wishing to conveniently style such "logical" paragraphs consisting of multiple
"structural" paragraphs can use the div
element instead of the p
element.
<div>For instance, this fantastic sentence has bullets relating to <ul> <li>wizards, <li>faster-than-light travel, and <li>telepathy, </ul> and is further discussed below.</div>
This example still has five structural paragraphs, but now the author can style just the div
instead of having to consider each part of the example separately.
4.4.2. The hr
element
- Categories:
- Flow content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag.
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
separator
(default - do not set) orpresentation
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLHRElement : HTMLElement {};
The hr
element represents a paragraph-level thematic break, e.g., a
scene change in a story, or a transition to another topic within a section of a reference book.
hr
element to separate topics within the section.
<section> <h1>Communication</h1> <p>There are various methods of communication. This section covers a few of the important ones used by the project.</p> <hr> <p>Communication stones seem to come in pairs and have mysterious properties:</p> <ul> <li>They can transfer thoughts in two directions once activated if used alone.</li> <li>If used with another device, they can transfer one’s consciousness to another body.</li> <li>If both stones are used with another device, the consciousnesses switch bodies.</li> </ul> <hr> <p>Radios use the electromagnetic spectrum in the meter range and longer.</p> <hr> <p>Signal flares use the electromagnetic spectrum in the nanometer range.</p> </section> <section> <h1>Food</h1> <p>All food at the project is rationed:</p> <dl> <dt>Potatoes</dt> <dd>Two per day</dd> <dt>Soup</dt> <dd>One bowl per day</dd> </dl> <hr> <p>Cooking is done by the chefs on a set rotation.</p> </section>
There is no need for an hr
element between the sections themselves, since the section
elements and the h1
elements imply thematic changes
themselves.
hr
element.
<p>Dudley was ninety-two, in his second life, and fast approaching
time for another rejuvenation. Despite his body having the physical
age of a standard fifty-year-old, the prospect of a long degrading
campaign within academia was one he regarded with dread. For a
supposedly advanced civilization, the Intersolar Commonwealth could be
appallingly backward at times, not to mention cruel.</p>
<p><i>Maybe it won’t be that bad</i>, he told himself. The lie was
comforting enough to get him through the rest of the night’s
shift.</p>
<hr>
<p>The Carlton AllLander drove Dudley home just after dawn. Like the
astronomer, the vehicle was old and worn, but perfectly capable of
doing its job. It had a cheap diesel engine, common enough on a
semi-frontier world like Gralmond, although its drive array was a
thoroughly modern photoneural processor. With its high suspension and
deep-tread tyres it could plough along the dirt track to the
observatory in all weather and seasons, including the metre-deep snow
of Gralmond’s winters.</p>
The hr
element does not affect the document’s outline.
4.4.3. The pre
element
- Categories:
- Flow content.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLPreElement : HTMLElement {};
The pre
element represents a block of preformatted text, in which structure is
represented by typographic conventions rather than by elements.
In the HTML syntax, a leading newline character immediately following the pre
element start tag is stripped.
Some examples of cases where the pre
element could be used:
-
Including an e-mail, with paragraphs indicated by blank lines, lists indicated by lines prefixed with a bullet, and so on.
-
Including fragments of computer code, with structure indicated according to the conventions of that language.
-
Displaying ASCII art.
Authors are encouraged to consider how preformatted text will be experienced when the formatting is lost, as will be the case for users of speech synthesizers, braille displays, and the like. For cases like ASCII art, it is likely that an alternative presentation, such as a textual description, would be more universally accessible to the readers of the document.
To represent a block of computer code, the pre
element can be used with a code
element; to represent a block of computer output the pre
element
can be used with a samp
element. Similarly, the kbd
element can be used
within a pre
element to indicate text that the user is to enter.
<p>This is the <code>Panel</code> constructor:</p> <pre><code>function Panel(element, canClose, closeHandler) { this.element = element; this.canClose = canClose; this.closeHandler = function () { if (closeHandler) closeHandler() }; }</code></pre>
samp
and kbd
elements are mixed in the
contents of a pre
element to show a session of Zork I.
<pre><samp>You are in an open field west of a big white house with a boarded front door. There is a small mailbox here. ></samp> <kbd>open mailbox</kbd> <samp>Opening the mailbox reveals: A leaflet. ></samp></pre>
pre
element to preserve its
unusual formatting, which forms an intrinsic part of the poem itself.
<pre> maxling it is with a heart heavy that i admit loss of a feline so loved a friend lost to the unknown (night) ~cdr 11dec07</pre>
4.4.4. The blockquote
element
- Categories:
- Flow content.
- Sectioning root.
- Palpable content.
- Sectioning root.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
cite
- Link to the source of the quotation. - Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLQuoteElement : HTMLElement { attribute DOMString cite; };
The
HTMLQuoteElement
interface is also used by theq
element.
The blockquote
element represents content that is quoted from another source,
optionally with a citation which must be within a footer
or cite
element, and optionally with in-line changes such as annotations and abbreviations.
Content inside a blockquote
other than citations and in-line changes must be quoted
from another source, whose address, if it has one, may be cited in the cite
attribute.
In cases where a page contains contributions from multiple people, such as comments on a blog post, 'another source' can include text from the same page, written by another person.
If the cite
attribute is present, it must be a valid URL potentially surrounded by spaces. To obtain the corresponding
citation link, the value of the attribute must be resolved relative to the element. User agents may allow users to follow such citation links, but they are primarily intended for
private use (e.g., by server-side scripts collecting statistics about a site’s use of quotations),
not for readers.
The content of a blockquote
may be abbreviated, may have context added or may have
annotations. Any such additions or changes to quoted text must be indicated in the text (at the
text level). This may mean the use of notational conventions or explicit remarks, such as
"emphasis mine".
<blockquote> <p>[Fred] then said he liked [...] fish.</p> </blockquote>
Quotation marks may be used to delineate between quoted text and annotations within a blockquote
.
<figure> <blockquote> "That monster custom, who all sense doth eat Of habit’s devil," <abbr title="et cetera">&c.</abbr> not in Folio "What a falling off was there ! From me, whose love was of that dignity That it went hand in hand even with the vow I made to her in marriage, and to decline Upon a wretch." </blockquote> <footer> — <cite class="title">Shakespeare manual</cite> by <cite class="author">Frederick Gard Fleay</cite>, p19 (in Google Books) </footer> </figure>
In the example above, the citation is contained within the footer
of a figure
element, this groups and associates the information, about the quote, with
the quote. The figcaption
element was not used, in this case, as a container for
the citation as it is not a caption.
Attribution for the quotation, may be be placed inside the blockquote
element, but
must be within a cite
element for in-text attributions or within a footer
element.
footer
after the quoted text, to
clearly relate the quote to its attribution:
<blockquote> <p>I contend that we are both atheists. I just believe in one fewer god than you do. When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours.</p> <footer>— <cite>Stephen Roberts</cite></footer> </blockquote>
cite
element on the last line of the quoted
text. Note that a link to the author is also included.
<blockquote> The people recognize themselves in their commodities; they find their soul in their automobile, hi-fi set, split-level home, kitchen equipment. — <cite><a href="https://en.wikipedia.org/wiki/Herbert_Marcuse">Herbert Marcuse</a></cite> </blockquote>
There is no formal method for indicating the markup in a blockquote
is from a
quoted source. It is suggested that if the footer
or cite
elements are
included and these elements are also being used within a blockquote
to identify
citations, the elements from the quoted source could be annotated with metadata to identify
their origin, for example by using the class
attribute (a defined
extensibility mechanism).
cite
element, which is annotated
using the class
attribute:
<blockquote> <p>My favorite book is <cite class="from-source">At Swim-Two-Birds</cite></p> <footer>- <cite>Mike[tm]Smith</cite></footer> </blockquote>
The other examples below show other ways of showing attribution.
blockquote
element is used in conjunction with a figure
element
and its figcaption
:
<figure> <blockquote> <p>The truth may be puzzling. It may take some work to grapple with. It may be counterintuitive. It may contradict deeply held prejudices. It may not be consonant with what we desperately want to be true. But our preferences do not determine what’s true. We have a method, and that method helps us to reach not absolute truth, only asymptotic approaches to the truth — never there, just closer and closer, always finding vast new oceans of undiscovered possibilities. Cleverly designed experiments are the key.</p> </blockquote> <figcaption><cite>Carl Sagan</cite>, in "<cite>Wonder and Skepticism</cite>", from the <cite>Skeptical Inquirer</cite> Volume 19, Issue 1 (January-February 1995)</figcaption> </figure>
cite
alongside blockquote
:
<p>His next piece was the aptly named <cite>Sonnet 130</cite>:</p> <blockquote cite="https://quotes.example.org/s/sonnet130.html"> <p>My mistress' eyes are nothing like the sun,<br> Coral is far more red, than her lips red,<br> ...
blockquote
to show what post a user
is replying to. The article
element is used for each post, to mark up the
threading.
<article> <h1><a href="https://bacon.example.com/?blog=109431">Bacon on a crowbar</a></h1> <article> <header><strong>t3yw</strong> 12 points 1 hour ago</header> <p>I bet a narwhal would love that.</p> <footer><a href="?pid=29578">permalink</a></footer> <article> <header><strong>greg</strong> 8 points 1 hour ago</header> <blockquote><p>I bet a narwhal would love that.</p></blockquote> <p>Dude narwhals don’t eat bacon.</p> <footer><a href="?pid=29579">permalink</a></footer> <article> <header><strong>t3yw</strong> 15 points 1 hour ago</header> <blockquote> <blockquote><p>I bet a narwhal would love that.</p></blockquote> <p>Dude narwhals don’t eat bacon.</p> </blockquote> <p>Next thing you’ll be saying they don’t get capes and wizard hats either!</p> <footer><a href="?pid=29580">permalink</a></footer> <article> <header><strong>boing</strong> -5 points 1 hour ago</header> <p>narwhals are worse than ceiling cat</p> <footer><a href="?pid=29581">permalink</a></footer> </article> </article> </article> <article> <header><strong>fred</strong> 1 points 23 minutes ago</header> <blockquote><p>I bet a narwhal would love that.</p></blockquote> <p>I bet they’d love to peel a banana too.</p> <footer><a href="?pid=29582">permalink</a></footer> </article> </article> </article>
blockquote
for short snippets, demonstrating that
one does not have to use p
elements inside blockquote
elements:
<p>He began his list of "lessons" with the following:</p> <blockquote>One should never assume that his side of the issue will be recognized, let alone that it will be conceded to have merits.</blockquote> <p>He continued with a number of similar points, ending with:</p> <blockquote>Finally, one should be prepared for the threat of breakdown in negotiations at any given moment and not be cowed by the possibility.</blockquote> <p>We shall now discuss these points...
Examples of how to represent a conversation are shown in a later section; it is not
appropriate to use the cite
and blockquote
elements for this purpose.
4.4.5. The ol
element
- Categories:
- Flow content.
- If the element’s children include at least one
li
element: Palpable content. - If the element’s children include at least one
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Zero or more
li
and script-supporting elements. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
reversed
- Number the list backwards.start
- Ordinal value of the first itemtype
- Kind of list marker. - Allowed ARIA role attribute values:
-
list
role (default - do not set),directory
,group
,listbox
,menu
,menubar
,presentation
,radiogroup
,tablist
,toolbar
ortree
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLOListElement : HTMLElement { attribute boolean reversed; attribute long start; attribute DOMString type; };
The ol
element represents a list of items, where the items have been
intentionally ordered, such that changing the order would change the meaning of the document.
The items of the list are the li
element child nodes of the ol
element,
in tree order.
The reversed
attribute is a boolean attribute. If present, it
indicates that the list is a descending list (..., 3, 2, 1). If the attribute is omitted, the list
is an ascending list (1, 2, 3, ...).
The start
attribute, if present, must be a valid integer giving the ordinal value of the first list item.
start
attribute is present, user agents must parse it as an integer,
in order to determine the attribute’s value. The default value, used if the attribute is missing
or if the value cannot be converted to a number according to the referenced algorithm, is 1 if
the element has no reversed
attribute, and is the number of child li
elements otherwise.
The first item in the list has the ordinal value given by the ol
element’s start
attribute, unless that li
element has a value
attribute with a value that can be successfully parsed, in which case it has the ordinal value given by that value
attribute.
Each subsequent item in the list has the ordinal value given by its value
attribute, if it has one, or, if it doesn’t, the ordinal value of the previous item, plus
one if the reversed
is absent, or minus one if it is present.
The type
attribute can be used to specify the kind of marker to use in the
list, in the cases where that matters (e.g., because items are to be referenced by their
number/letter). The attribute, if specified, must have a value that is a case-sensitive match for one of the characters given in the first cell of one of the rows of the following table. The type
attribute represents the state given in the cell in the
second column of the row whose first cell matches the attribute’s value; if none of the cells
match, or if the attribute is omitted, then the attribute represents the decimal state.
type
attribute of the ol
element. Numbers less than or equal to zero
should always use the decimal system regardless of the type
attribute.
For CSS user agents, a mapping for this attribute to the list-style-type CSS property is given in the §10 Rendering section (the mapping is straightforward: the states above have the same names as their corresponding CSS values).
It is possible to redefine the default CSS list styles used to implement this attribute in CSS user agents; doing so will affect how list items are rendered.
reversed
, start
, and type
IDL attributes must reflect the respective content
attributes of the same name. The start
IDL attribute has the same default as its
content attribute. ol
element is therefore appropriate. Compare this list to the equivalent list in the ul
section to see an example of the same items using the ul
element.
<p>I have lived in the following countries (given in the order of when I first lived there):</p> <ol> <li>Switzerland <li>United Kingdom <li>United States <li>Norway </ol>
Note how changing the order of the list changes the meaning of the document. In the following example, changing the relative order of the first two items has changed the birthplace of the author:
<p>I have lived in the following countries (given in the order of when I first lived there):</p> <ol> <li>United Kingdom <li>Switzerland <li>United States <li>Norway </ol>
4.4.6. The ul
element
- Categories:
- Flow content.
- If the element’s children include at least one
li
element: Palpable content. - If the element’s children include at least one
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Zero or more
li
and script-supporting elements. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
list
role (default - do not set),directory
,group
,listbox
,menu
,menubar
,presentation
,radiogroup
,tablist
,toolbar
ortree
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLUListElement : HTMLElement {};
The ul
element represents a list of items, where the order of the items is not
important — that is, where changing the order would not materially change the meaning of the
document.
The items of the list are the li
element child nodes of the ul
element.
ul
element is therefore appropriate. Compare this list to the equivalent list in the ol
section to see an example of the same items using the ol
element.
<p>I have lived in the following countries:</p> <ul> <li>Norway <li>Switzerland <li>United Kingdom <li>United States </ul>
Note that changing the order of the list does not change the meaning of the document. The items in the snippet above are given in alphabetical order, but in the snippet below they are given in order of the size of their current account balance in 2007, without changing the meaning of the document whatsoever:
<p>I have lived in the following countries:</p> <ul> <li>Switzerland <li>Norway <li>United Kingdom <li>United States </ul>
4.4.7. The li
element
- Categories:
- None.
- Contexts in which this element can be used:
- Inside
ol
elements.- Inside
ul
elements. - Inside
- Content model:
- Flow content.
- Tag omission in text/html:
- An
li
element’s end tag may be omitted if theli
element is immediately followed by anotherli
element or if there is no more content in the parent element. - Content attributes:
- Global attributes
- If the element is not a child of an
ul
ormenu
element:value
- If the element is not a child of an
- Allowed ARIA role attribute values:
-
listitem
role (default - do not set),menuitem
,menuitemcheckbox
,menuitemradio
,option
,presentation
,radio
,separator
,tab
ortreeitem
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLLIElement : HTMLElement { attribute long value; };
The li
element represents a list item. If its parent element is an ol
, ul
, or menu
element, then the element is an item of the
parent element’s list, as defined for those elements. Otherwise, the list item has no defined
list-related relationship to any other li
element.
If the parent element is an ol
element, then the li
element has an ordinal value.
The value
attribute, if present, must be a valid integer giving the ordinal value of the list item.
value
attribute is present, user agents must parse it as an integer,
in order to determine the attribute’s value. If the attribute’s value cannot be converted to a
number, the attribute must be treated as if it was absent. The attribute has no default value.
The value
attribute is processed relative to the element’s parent ol
element (q.v.), if there is one. If there is not, the attribute has no effect.
The value
IDL attribute must reflect the value of the value
content attribute.
figure
element and its figcaption
element.
<figure> <figcaption>The top 10 movies of all time</figcaption> <ol> <li value="10"><cite>Josie and the Pussycats</cite>, 2001</li> <li value="9"><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li> <li value="8"><cite>A Bug’s Life</cite>, 1998</li> <li value="7"><cite>Toy Story</cite>, 1995</li> <li value="6"><cite>Monsters, Inc</cite>, 2001</li> <li value="5"><cite>Cars</cite>, 2006</li> <li value="4"><cite>Toy Story 2</cite>, 1999</li> <li value="3"><cite>Finding Nemo</cite>, 2003</li> <li value="2"><cite>The Incredibles</cite>, 2004</li> <li value="1"><cite>Ratatouille</cite>, 2007</li> </ol> </figure>
The markup could also be written as follows, using the reversed
attribute on the ol
element:
<figure> <figcaption>The top 10 movies of all time</figcaption> <ol reversed> <li><cite>Josie and the Pussycats</cite>, 2001</li> <li><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li> <li><cite>A Bug’s Life</cite>, 1998</li> <li><cite>Toy Story</cite>, 1995</li> <li><cite>Monsters, Inc</cite>, 2001</li> <li><cite>Cars</cite>, 2006</li> <li><cite>Toy Story 2</cite>, 1999</li> <li><cite>Finding Nemo</cite>, 2003</li> <li><cite>The Incredibles</cite>, 2004</li> <li><cite>Ratatouille</cite>, 2007</li> </ol> </figure>
While it is conforming to include heading elements (e.g., h1
) inside li
elements, it likely does not convey the semantics that the author intended. A heading starts a
new section, so a heading in a list implicitly splits the list into spanning multiple sections.
4.4.8. The dl
element
- Categories:
- Flow content.
- If the element’s children include at least one name-value group: Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Zero or more groups each consisting of one or more
dt
elements followed by one or moredd
elements, optionally intermixed with script-supporting elements. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
list
role (default - do not set),directory
,group
,listbox
,menu
,menubar
,presentation
,radiogroup
,tablist
,toolbar
ortree
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLDListElement : HTMLElement {};
The dl
element represents a description list of zero or more term-description groups. Each term-description group consists of one or more terms (represented by dt
elements), and one or more descriptions (represented by dd
elements).
Term-description groups may be names and definitions, questions and answers, categories and topics, or any other groups of term-description pairs.
In this example a dl
is used to represent a simple list of names and descriptions:
<dl> <dt>Blanco tequila</dt> <dd>The purest form of the blue agave spirit...</dd> <dt>Reposado tequila</dt> <dd>Typically aged in wooden barrels for between two and eleven months...</dd> </dl>
Each term within a term-description group must be represented by a single dt
element. The descriptions within a term-description group are alternatives. Each description must be represented by a single dd
element.
In this example a dl
element represents a set of terms, each of which has multiple descriptions:
<p>Information about the rock band Queen:</p> <dl> <dt>Members</dt> <dd>Brian May</dd> <dd>Freddie Mercury</dd> <dd>John Deacon</dd> <dd>Roger Taylor</dd> <dt>Record labels</dt> <dd>EMI</dd> <dd>Parlophone</dd> <dd>Capitol</dd> <dd>Hollywood</dd> <dd>Island</dd> </dl>
The order of term-description groups within a dl
element, and the order of terms and descriptions within each group, may be significant.
In this example a dl
is used to show a set of instructions, where the order of the instructions is important:
<p>Determine the victory points as follows (use the first matching case):</p> <dl> <dt> If you have exactly five gold coins </dt> <dd> You get five victory points </dd> <dt> If you have one or more gold coins, and you have one or more silver coins </dt> <dd> You get two victory points </dd> <dt> If you have one or more silver coins </dt> <dd> You get one victory point </dd> <dt> Otherwise </dt> <dd> You get no victory points </dd> </dl>
If a dl
element contains no dt
or dd
child elements, it contains no term-description groups.
If a dl
element has one or more non-whitespace text node children, or has children that are neither dt
or dd
elements, then all such text nodes and elements as well as their descendants (including any dt
and dd
elements) do not form part of any term-description group within the dl
.
If a dl
element has one or more dt
element children, but no dd
element children, then it consists of one group with terms but no descriptions.
If a dl
element has one or more dd
element children, but no dt
element children, it consists of one group with descriptions but no terms.
If a dd
element is the first child of a dl
element (excepting a script-supporting element), the first group has no associated term.
If a dt
element is the last child of a dl
element (excepting a script-supporting element), the last group has no associated descriptions.
Note: when a dl
element does not match its content model, it is often because a dd
element has been used instead of a dt
element, or vice versa.
4.4.9. The dt
element
- Categories:
- None.
- Contexts in which this element can be used:
- Before
dd
ordt
elements insidedl
elements. - Content model:
- Flow content, but with no
header
,footer
, sectioning content, or heading content descendants. - Tag omission in text/html:
- A
dt
element’s end tag may be omitted if thedt
element is immediately followed by anotherdt
element or add
element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- None.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes None - Any
- DOM interface:
- Uses
HTMLElement
.
The dt
element represents a term, part of a term-description group in a description list (dl
element).
In this example the dt
elements represent questions and the dd
elements the answers:
<dl> <dt>What is my favorite drink?</dt> <dd>Tea</dd> <dt>What is my favorite food?</dt> <dd>Sushi</dd> <dt>What is my favourite film?</dt> <dd>What a Wonderful Life</dd> </dl>
When used within a dl
element, the dt
element does not necessarily represent the definition for a term. The dfn
element should be used to represent a definition.
In this example the dfn
element indicates that the dt
element contains a defined term, the definition for which is represented by the dd
element:
<dl> <dt lang="en-us"><dfn>Color</dfn></dt> <dt lang="en-gb"><dfn>Colour</dfn></dt> <dd>A sensation which (in humans) derives from the ability of the fine structure of the eye to distinguish three differently filtered analyses of a view.</dd> </dl>
4.4.10. The dd
element
- Categories:
- None.
- Contexts in which this element can be used:
- After
dt
ordd
elements insidedl
elements. - Content model:
- Flow content.
- Tag omission in text/html:
- A
dd
element’s end tag may be omitted if thedd
element is immediately followed by anotherdd
element or adt
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The dd
element represents a description, part of a term-description group in a description list (dl
element).
In this example the dd
elements represent the keys that invoke the keycodes indicated in the dt
elements:
<dl> <dt>37</dt> <dd>Left</dd> <dt>38</dt> <dd>Right</dd> <dt>39</dt> <dd>Up</dd> <dt>40</dt> <dd>Down</dd> </dl>
4.4.11. The figure
element
- Categories:
- Flow content.
- Sectioning root.
- Palpable content.
- Sectioning root.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content optionally including a
figcaption
child element. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The figure
element represents some flow content, optionally with a
caption, that is self-contained (like a complete sentence) and is typically referenced as a single
unit from the main flow of the document.
Self-contained in this context does not necessarily mean independent. For example, each sentence
in a paragraph is self-contained; an image that is part of a sentence would be inappropriate for figure
, but an entire sentence made of images would be fitting.
The element can thus be used to annotate illustrations, diagrams, photos, code listings, etc.
figure
is referred to from the main content of the document by identifying
it by its caption (e.g., by figure number), it enables such content to be easily moved away from
that primary content, e.g., to the side of the page, to dedicated pages, or to an appendix,
without affecting the flow of the document.
If a figure
element is referenced by its relative position, e.g., "in the photograph
above" or "as the next figure shows", then moving the figure would disrupt the page’s meaning.
Authors are encouraged to consider using labels to refer to figures, rather than using such
relative references, so that the page can easily be restyled without affecting the page’s
meaning.
The figcaption
descendant of figure
, if any, represents the caption of the figure
element’s contents. If there is no child figcaption
element, then there is no caption.
A figure
element’s contents are part of the surrounding flow. If the purpose of the
page is to display the figure, for example a photograph on an image sharing site, the figure
and figcaption
elements can be used to explicitly provide a
caption for that figure. For content that is only tangentially related, or that serves a separate
purpose than the surrounding flow, the aside
element should be used (and can itself
wrap a figure
). For example, a pull quote that repeats content from an article
would be more appropriate in an aside
than in a figure
, because it isn’t part of the content, it’s a repetition of the content for
the purposes of enticing readers or highlighting key topics.
figure
element to mark up a code listing.
<p>In <a href="#l4">listing 4</a> we see the primary core interface API declaration.</p> <figure id="l4"> <figcaption>Listing 4. The primary core interface API declaration.</figcaption> <pre><code>interface PrimaryCore { boolean verifyDataLine(); void sendData(in sequence<byte> data); void initSelfDestruct(); }</code></pre> </figure> <p>The API is designed to use UTF-8.</p>
figure
element to mark up a photo that is the main content of the
page (as in a gallery).
<!DOCTYPE HTML> <title>Bubbles at work — My Gallery™</title> <figure> <img src="bubbles-work.jpeg" alt="Bubbles, sitting in his office chair, works on his latest project intently."> <figcaption>Bubbles at work</figcaption> </figure> <nav><a href="19414.html">Prev</a> — <a href="19416.html">Next</a></nav>
figure
would be inappropriate.
<h2>Malinko’s comics</h2> <p>This case centered on some sort of "intellectual property" infringement related to a comic (see Exhibit A). The suit started after a trailer ending with these words: <blockquote> <img src="promblem-packed-action.png" alt="ROUGH COPY! Promblem-Packed Action!"> </blockquote> <p>...was aired. A lawyer, armed with a Bigger Notebook, launched a preemptive strike using snowballs. A complete copy of the trailer is included with Exhibit B. <figure> <img src="ex-a.png" alt="Two squiggles on a dirty piece of paper."> <figcaption>Exhibit A. The alleged <cite>rough copy</cite> comic.</figcaption> </figure> <figure> <video src="ex-b.mov"></video> <figcaption>Exhibit B. The <cite>Rough Copy</cite> trailer.</figcaption> </figure> <p>The case was resolved out of court.
figure
.
<figure> <p>'Twas brillig, and the slithy toves<br> Did gyre and gimble in the wabe;<br> All mimsy were the borogoves,<br> And the mome raths outgrabe.</p> <figcaption><cite>Jabberwocky</cite> (first verse). Lewis Carroll, 1832-98</figcaption> </figure>
figure
elements are used to provide both a group caption and individual captions for
each figure in the group:
<figure> <figcaption>The castle through the ages: 1423, 1858, and 1999 respectively.</figcaption> <figure> <figcaption>Etching. Anonymous, ca. 1423.</figcaption> <img src="castle1423.jpeg" alt="The castle has one tower, and a tall wall around it."> </figure> <figure> <figcaption>Oil-based paint on canvas. Maria Towle, 1858.</figcaption> <img src="castle1858.jpeg" alt="The castle now has two towers and two walls."> </figure> <figure> <figcaption>Film photograph. Peter Jankle, 1999.</figcaption> <img src="castle1999.jpeg" alt="The castle lies in ruins, the original tower all that remains in one piece."> </figure> </figure>
title
attributes in place of the nested figure
/figcaption
pairs):
<figure> <img src="castle1423.jpeg" title="Etching. Anonymous, ca. 1423." alt="The castle has one tower, and a tall wall around it."> <img src="castle1858.jpeg" title="Oil-based paint on canvas. Maria Towle, 1858." alt="The castle now has two towers and two walls."> <img src="castle1999.jpeg" title="Film photograph. Peter Jankle, 1999." alt="The castle lies in ruins, the original tower all that remains in one piece."> <figcaption>The castle through the ages: 1423, 1858, and 1999 respectively.</figcaption> </figure>
<article> <h1>Fiscal negotiations stumble in Congress as deadline nears</h1> <figure> <img src="obama-reid.jpeg" alt="Obama and Reid sit together smiling in the Oval Office."> <figcaption>Barack Obama and Harry Reid. White House press photograph.</figcaption> </figure> <p>Negotiations in Congress to end the fiscal impasse sputtered on Tuesday, leaving both chambers grasping for a way to reopen the government and raise the country’s borrowing authority with a Thursday deadline drawing near.</p> ... </article>
4.4.12. The figcaption
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a descendant of a
figure
element. - Content model:
- Flow content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The figcaption
element represents a caption or legend for the rest of the
contents of the figcaption
element’s parent figure
element, if any.
4.4.13. The main
element
- Categories:
- Flow content.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
-
main
role (default - do not set) orpresentation
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
The main
element represents the main content of the body of a document or application.
The main
element is not sectioning content and has no effect on the document outline
Authors must not include the main
element as a descendant of an article
, aside
, footer
, header
or nav
element.
The main
element is not suitable for use to identify the main content areas of sub
sections of a document or application. The simplest solution is to not mark up the main content
of a sub section at all, and just leave it as implicit, but an author could use a §4.4 Grouping content or sectioning content element as appropriate.
In the following example, we see 2 articles about skateboards (the main topic of a Web page) the
main topic content is identified by the use of the main
element.
<!-- other content --> <main> <h1>Skateboards</h1> <p>The skateboard is the way cool kids get around</p> <article> <h2>Longboards</h2> <p>Longboards are a type of skateboard with a longer wheelbase and larger, softer wheels.</p> <p>... </p> <p>... </p> </article> <article> <h2>Electric Skateboards</h2> <p>These no longer require the propelling of the skateboard by means of the feet; rather an electric motor propels the board, fed by an electric battery.</p> <p>... </p> <p>... </p> </article> </main> <!-- other content -->
Here is a graduation programme the main content section is defined by the use of the main
element. Note in this example the main
element contains a nav
element consisting of links to sub sections of the main content.
<!DOCTYPE html> <html lang="en"> <head> <title>Graduation Ceremony Summer 2022</title> </head> <body> <header>The Lawson Academy: <nav> <ul> <li><a href="courses.html">Courses</a></li> <li><a href="fees.html">Fees</a></li> <li><a>Graduation</a></li> </ul> </nav> </header> <main> <h1>Graduation</h1> <nav> <ul> <li><a href="#ceremony">Ceremony</a></li> <li><a href="#graduates">Graduates</a></li> <li><a href="#awards">Awards</a></li> </ul> </nav> <h2 id="ceremony">Ceremony</h2> <p>Opening Procession</p> <p>Speech by Valedictorian</p> <p>Speech by Class President</p> <p>Presentation of Diplomas</p> <p>Closing Speech by Headmaster</p> <h2 id="graduates">Graduates</h2> <ul> <li>Eileen Williams</li> <li>Andy Maseyk</li> <li>Blanca Sainz Garcia</li> <li>Clara Faulkner</li> <li>Gez Lemon</li> <li>Eloisa Faulkner</li> </ul> <h2 id="awards">Awards</h2> <ul> <li>Clara Faulkner</li> <li>Eloisa Faulkner</li> <li>Blanca Sainz Garcia</li> </ul> </main> <footer> Copyright 2012 B.lawson</footer> </body> </html>
In the next example, both the header
and the footer
are outside the main
element
because they are generic to the website and not specific to main
's content.
<!DOCTYPE html> <html lang="en"> <head> <title>Great Dogs for Families</title> </head> <body> <header> <h1>The Border Terrier</h1> <nav> <ul> <li><a href="index.html">Home</a></li> <li><a href="about.html">About</a></li> <li><a href="health.html">Health</a></li> </ul> </nav> </header> <main> <h2>Welcome!</h2> <p>This site is all about the Border Terrier, the best breed of dog that there is!</p> </main> <footer> <small>Copyright © <time datetime="2013">2013</time> by I. Devlin</small> </footer> </body> </html>
Here, the same generic header
and footer
elements remain outside main
, but there
is an additional header
element within the main
element as its content is relevant to
the content within main
because it contains a relevant heading and in-page navigation.
The in-page navigation is repeated within a footer
which is again within the main
element.
<!DOCTYPE html> <html lang="en"> <head> <title>Great Dogs for Families</title> </head> <body> <header> <h1>The Border Terrier</h1> <nav> <ul> <li><a href="index.html">Home</a></li> <li><a href="about.html">About</a></li> <li><a href="health.html">Health</a></li> </ul> </nav> </header> <main> <section> <header> <h2>About</h2> <nav> <ul> <li><a href="#basic">Basic</a></li> <li><a href="#app">Appearance</a></li> <li><a href="#temp">Temperament</a></li> </ul> </nav> </header> <section id="basic"> <h3>Basic Information</h3> <p>The Border Terrier is a small, rough-coated breed of dog of the terrier group, originally bred as fox and vermin hunters. [...]</p> </section> <section id="app"> <h3>Appearance</h3> <p>Identifiable by their otter-shaped heads, Border Terriers have a broad skull and short (although many be fairly long), strong muzzle with a scissors bite. [...]</p> </section> <section id="temp"> <h3>Temperament</h3> <p>Though sometimes stubborn and strong willed, border terriers are, on the whole very even tempered, and are friendly and rarely aggressive. [...] </p> </section> <footer> <a href="#basic">Basic</a> - <a href="#app">Appearance</a> - <a href="#temp">Temperament</a> </footer> </section> </main> <footer> <small>Copyright © <time datetime="2013">2013</time> by I. Devlin</small> </footer> </body> </html>
This example is largely the same as the previous one except that it includes an aside
.
The content of the aside
is considered to be relevant to the content within the main
element, which is all about the Border Terrier, so the aside
is placed within the main
element.
<!DOCTYPE html> <html lang="en"> <head> <title>Great Dogs for Families</title> </head> <body> <header> <h1>The Border Terrier</h1> <nav> <ul> <li><a href="index.html">Home</a></li> <li><a href="about.html">About</a></li> <li><a href="health.html">Health</a></li> </ul> </nav> </header> <main> <section> <header> <h2>About</h2> <nav> <ul> <li><a href="#basic">Basic</a></li> <li><a href="#app">Appearance</a></li> <li><a href="#temp">Temperament</a></li> </ul> </nav> </header> <section id="basic"> <h3>Basic Information</h3> <p>The Border Terrier is a small, rough-coated breed of dog of the terrier group, originally bred as fox and vermin hunters. [...]</p> </section> <section id="app"> <h3>Appearance</h3> <p>Identifiable by their otter-shaped heads, Border Terriers have a broad skull and short (although many be fairly long), strong muzzle with a scissors bite. [...]</p> </section> <section id="temp"> <h3>Temperament</h3> <p>Though sometimes stubborn and strong willed, border terriers are, on the whole very even tempered, and are friendly and rarely aggressive. [...] </p> </section> <aside> <h3>History</h3> <p>The Border Terrier originates in, and takes its name from the Scottish borders. [...] </p> </aside> <footer> <a href="#basic">Basic</a> - <a href="#app">Appearance</a> - <a href="#temp">Temperament</a> </footer> </section> </main> <footer> <small>Copyright © <time datetime="2013">2013</time> by I. Devlin</small> </footer> </body> </html>
In the following example, two aside
elements containg adverts have been placed outside
the main
element as their content is not specific to the content within main
. These aside
s could be on any page, as they are as generic as the header
and footer
shown.
<!DOCTYPE html> <html lang="en"> <head> <title>Great Dogs for Families</title> </head> <body> <header> <h1>The Border Terrier</h1> <nav> <ul> <li><a href="index.html">Home</a></li> <li><a href="about.html">About</a></li> <li><a href="health.html">Health</a></li> </ul> </nav> </header> <main> <h2>Welcome!</h2> <p>This site is all about the Border Terrier, the best breed of dog that there is!</p> </main> <aside class="advert"> <h2>Border Farm Breeders</h2> <p>We are a certified breeder of Border Terriers, contact us at...</p> </aside> <aside class="advert"> <h2>Grumpy’s Pet Shop</h2> <p>Get all your pet’s needs at our shop!</p> </aside> <footer> <small>Copyright © <time datetime="2013">2013</time> by I. Devlin</small> </footer> </body> </html>
4.4.14. The div
element
- Categories:
- Flow content.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLDivElement : HTMLElement {};
The div
element has no special meaning at all. It represents its children. It
can be used with the class
, lang
, and title
attributes to
mark up semantics common to a group of consecutive elements.
Authors are strongly encouraged to view the div
element as an element of last
resort, for when no other element is suitable. Use of more appropriate elements instead of the div
element leads to better accessibility for readers and easier maintainability
for authors.
article
, a chapter using section
, a page’s navigation aids using nav
, and a group of form
controls using fieldset
.
On the other hand, div
elements can be useful for stylistic purposes or to wrap
multiple paragraphs within a section that are all to be annotated in a similar way. In the
following example, we see div
elements used as a way to set the language of two
paragraphs at once, instead of setting the language on the two paragraph elements separately:
<article lang="en-US"> <h2>My use of language and my cats</h2> <p>My cat’s behavior hasn’t changed much since her absence, except that she plays her new physique to the neighbors regularly, in an attempt to get pets.</p> <div lang="en-GB"> <p>My other cat, colored black and white, is a sweetie. He followed us to the pool today, walking down the pavement with us. Yesterday he apparently visited our neighbours. I wonder if he recognizes that their flat is a mirror image of ours.</p> <p>Hm, I just noticed that in the last paragraph I used British English. But I’m supposed to write in American English. So I shouldn’t say "pavement" or "flat" or "color"...</p> </div> <p>I should say "sidewalk" and "apartment" and "color"!</p> </article>
4.5. Text-level semantics
4.5.1. The a
element
- Categories:
- Flow content.
- Phrasing content.
- If the element has an
href
attribute: Interactive content.- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Transparent, but there must be no interactive content or
a
element descendants. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
href
- Address of the hyperlinktarget
- Default browsing context for hyperlink navigation and §4.10.22 Form submissiondownload
- Whether to download the resource instead of navigating to it, and its file name if sorel
— Relationship of this document (or subsection/topic) to the destination resourcerev
— Reverse link relationship of the destination resource to this document (or subsection/topic)hreflang
- Language of the linked resourcetype
- Hint for the type of the referenced resource - Allowed ARIA role attribute values:
-
link
(default - do not set),button
,checkbox
,menuitem
,menuitemcheckbox
,menuitemradio
,radio
,switch
[WAI-ARIA-1.1],tab
ortreeitem
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLAnchorElement : HTMLElement { attribute DOMString target; attribute DOMString download; attribute DOMString rel; attribute DOMString rev; [SameObject, PutForwards=value] readonly attribute DOMTokenList relList; attribute DOMString hreflang; attribute DOMString type; attribute DOMString text; }; HTMLAnchorElement implements HTMLHyperlinkElementUtils;
If the a
element has an href
attribute, then it represents a hyperlink (a hypertext anchor) labeled by its contents.
If the a
element has no href
attribute, then the element represents a placeholder for where a link might otherwise have been placed, if it had been
relevant, consisting of just the element’s contents.
The target
, download
, rel
, rev
, hreflang
, and type
attributes must be omitted if the href
attribute is not present.
If a site uses a consistent navigation toolbar on every page, then the link that would
normally link to the page itself could be marked up using an a
element:
<nav> <ul> <li> <a href="/">Home</a> </li> <li> <a href="/news">News</a> </li> <li> <a>Examples</a> </li> <li> <a href="/legal">Legal</a> </li> </ul> </nav>
href
, target
, download
, and attributes affect what
happens when users follow hyperlinks or download hyperlinks created using the a
element. The rel
, rev
, hreflang
, and type
attributes may be used to indicate to the user the likely nature of the target resource before
the user follows the link.
The activation behavior of a
elements that create hyperlinks is to
run the following steps:
-
If the
a
element’sDocument
is not fully active, then abort these steps. -
If either the
a
element has adownload
attribute and the algorithm is not allowed to show a popup, or the element’starget
attribute is present and applying the rules for choosing a browsing context given a browsing context name, using the value of thetarget
attribute as the browsing context name, would result in there not being a chosen browsing context, then run these substeps:-
If there is an entry settings object, throw an
InvalidAccessError
exception. -
Abort these steps without following the hyperlink.
-
-
If the target of the
click
event is animg
element with anismap
attribute specified, then server-side image map processing must be performed, as follows:-
If the
click
event was a real pointing-device-triggeredclick
event on theimg
element, then let x be the distance in CSS pixels from the left edge of the image’s left border, if it has one, or the left edge of the image otherwise, to the location of the click, and let y be the distance in CSS pixels from the top edge of the image’s top border, if it has one, or the top edge of the image otherwise, to the location of the click. Otherwise, let x and y be zero. -
Let hyperlink suffix be a U+003F QUESTION MARK character, the value of x expressed as a base-ten integer using ASCII digits, a U+002C COMMA character (,), and the value of y expressed as a base-ten integer using ASCII digits.
-
-
Finally, the user agent must follow the hyperlink or download the hyperlink created by the
a
element, as determined by thedownload
attribute and any expressed user preference, passing hyperlink suffix, if the steps above defined it.
- a .
text
- Same as
textContent
.
download
, target
, rel
, rev
, hreflang
, and type
, must reflect the
respective content attributes of the same name.
The IDL attribute relList
must reflect the rel
content attribute.
The text
IDL attribute, on getting, must return the same value as the textContent
IDL attribute on the element, and on setting, must act as if the textContent
IDL attribute on the element had been set to the new value.
The a
element also supports the HTMLHyperlinkElementUtils
interface. [URL]
When the element is created, and whenever the element’s href
content attribute is
set, changed, or removed, the user agent must invoke the element’s HTMLHyperlinkElementUtils
interface’s set the input algorithm with the value of the href
content
attribute, if any, or the empty string otherwise, as the given value.
The element’s HTMLHyperlinkElementUtils
interface’s get the base algorithm must simply return
the document base URL.
The element’s HTMLHyperlinkElementUtils
interface’s query encoding is the document’s character encoding.
When the element’s HTMLHyperlinkElementUtils
interface invokes its update steps with a string value, the user agent must set the element’s href
content attribute to
the string value.
a
element may be wrapped around entire paragraphs, lists, tables, and so forth,
even entire sections, so long as there is no interactive content within (e.g., buttons or other
links). This example shows how this can be used to make an entire advertising block into a link:
<aside class="advertising"> <h1>Advertising</h1> <a href="https://ad.example.com/?adid=1929&pubid=1422"> <section> <h1>Mellblomatic 9000!</h1> <p>Turn all your widgets into mellbloms!</p> <p>Only $9.99 plus shipping and handling.</p> </section> </a> <a href="https://ad.example.com/?adid=375&pubid=1422"> <section> <h1>The Mellblom Browser</h1> <p>Web browsing at the speed of light.</p> <p>No other browser goes faster!</p> </section> </a> </aside>
4.5.2. The em
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The em
element represents stress emphasis of its contents.
The level of stress that a particular piece of content has is given by its number of ancestor em
elements.
The placement of stress emphasis changes the meaning of the sentence. The element thus forms an integral part of the content. The precise way in which stress is used in this way depends on the language.
<p>Cats are cute animals.</p>
By emphasizing the first word, the statement implies that the kind of animal under discussion is in question (maybe someone is asserting that dogs are cute):
<p><em>Cats</em> are cute animals.</p>
Moving the stress to the verb, one highlights that the truth of the entire sentence is in question (maybe someone is saying cats are not cute):
<p>Cats <em>are</em> cute animals.</p>
By moving it to the adjective, the exact nature of the cats is reasserted (maybe someone suggested cats were mean animals):
<p>Cats are <em>cute</em> animals.</p>
Similarly, if someone asserted that cats were vegetables, someone correcting this might emphasize the last word:
<p>Cats are cute <em>animals</em>.</p>
By emphasizing the entire sentence, it becomes clear that the speaker is fighting hard to get the point across. This kind of stress emphasis also typically affects the punctuation, hence the exclamation mark here.
<p><em>Cats are cute animals!</em></p>
Anger mixed with emphasizing the cuteness could lead to markup such as:
<p><em>Cats are <em>cute</em> animals!</em></p>
em
element isn’t a generic "italics" element. Sometimes, text is intended to
stand out from the rest of the paragraph, as if it was in a different mood or voice. For this,
the i
element is more appropriate.
The em
element also isn’t intended to convey importance; for that purpose, the strong
element is more appropriate.
4.5.3. The strong
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The strong
element represents strong importance, seriousness, or
urgency for its contents.
Importance: The strong
element can be used in a heading, caption,
or paragraph to distinguish the part that really matters from other parts that might be more
detailed, more jovial, or merely boilerplate.
For example, the first word of the previous paragraph is marked up with strong
to distinguish it from the more detailed text in the rest of the
paragraph.
Seriousness: The strong
element can be used to mark up a warning
or caution notice.
Urgency: The strong
element can be used to denote contents that
the user needs to see sooner than other parts of the document.
The relative level of importance of a piece of content is given by its number of ancestor strong
elements; each strong
element increases the importance of its
contents.
Changing the importance of a piece of text with the strong
element does not change
the meaning of the sentence.
strong
:
<h1>Chapter 1: <strong>The Praxis</strong></h1>
In the following example, the name of the diagram in the caption is marked up with strong
, to distinguish it from boilerplate text (before) and the description
(after):
<figcaption>Figure 1. <strong>Ant colony dynamics</strong>. The ants in this colony areaffected by the heat source (upper left) and the food source (lower right).</figcaption>
In this example, the heading is really "Flowers, Bees, and Honey", but the author has added a
light-hearted addition to the heading. The strong
element is thus used to mark up
the first part to distinguish it from the latter part.
<h1><strong>Flowers, Bees, and Honey</strong> and other things I don’t understand</h1>
<p><strong>Warning.</strong> This dungeon is dangerous. <strong>Avoid the ducks.</strong> Take any gold you find. <strong><strong>Do not take any of the diamonds</strong>, they are explosive and <strong>will destroy anything within ten meters.</strong></strong> You have been warned.</p>
strong
element is used to denote the part of the text that
the user is intended to read first.
<p>Welcome to Remy, the reminder system.</p> <p>Your tasks for today:</p> <ul> <li><p><strong>Turn off the oven.</strong></p></li> <li><p>Put out the trash.</p></li> <li><p>Do the laundry.</p></li> </ul>
4.5.4. The small
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The small
element represents side comments such as small print.
Small print typically features disclaimers, caveats, legal restrictions, or copyrights. Small print is also sometimes used for attribution, or for satisfying licensing requirements.
The small
element does not "de-emphasize" or lower the importance of text
emphasized by the em
element or marked as important with the strong
element. To mark text as not emphasized or important, simply do not mark it up with the em
or strong
elements respectively.
The small
element should not be used for extended spans of text, such as multiple
paragraphs, lists, or sections of text. It is only intended for short runs of text. The text of a
page listing terms of use, for instance, would not be a suitable candidate for the small
element: in such a case, the text is not a side comment, it is the main content
of the page.
small
element is used to indicate that value-added tax is
not included in a price of a hotel room:
<dl> <dt>Single room <dd>199 € <small>breakfast included, VAT not included</small> <dt>Double room <dd>239 € <small>breakfast included, VAT not included</small> </dl>
small
element is used for a side comment in an article.
<p>Example Corp today announced record profits for the second quarter <small>(Full Disclosure: Foo News is a subsidiary of Example Corp)</small>, leading to speculation about a third quarter merger with Demo Group.</p>
This is distinct from a sidebar, which might be multiple paragraphs long and is removed from the main flow of text. In the following example, we see a sidebar from the same article. This sidebar also has small print, indicating the source of the information in the sidebar.
<aside> <h1>Example Corp</h1> <p>This company mostly creates small software and Web sites.</p> <p>The Example Corp company mission is "To provide entertainment and news on a sample basis".</p> <p><small>Information obtained from <a href="https://example.com/about.html">example.com</a> home page.</small></p> </aside>
In this last example, the small
element is marked as being important small print.
<p><strong><small>Continued use of this service will result in a kiss.</small></strong></p>
4.5.5. The s
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The s
element represents contents that are no longer accurate or no longer
relevant.
The s
element is not appropriate when indicating document edits; to mark a span of
text as having been removed from a document, use the del
element.
<p>Buy our Iced Tea and Lemonade!</p> <p><s>Recommended retail price: $3.99 per bottle</s></p> <p><strong>Now selling for just $2.99 a bottle!</strong></p>
4.5.6. The cite
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The cite
element represents a reference to a creative work. It must include
the title of the work or the name of the author (person, people or organization) or an URL
reference, or a reference in abbreviated form as per the conventions used for the addition of
citation metadata.
Creative works include a book, a paper, an essay, a poem, a score, a song, a script, a film, a TV show, a game, a sculpture, a painting, a theatre production, a play, an opera, a musical, an exhibition, a legal case report, a computer program, , a web site, a web page, a blog post or comment, a forum post or comment, a tweet, a written or oral statement, etc.
cite
element:
<p>In the words of <cite>Charles Bukowski</cite> - <q>An intellectual says a simple thing in a hard way. An artist says a hard thing in a simple way.</q></p>
cite
element:
<blockquote class="twitter-tweet"> <p>♥ Bukowski in <a href="https://twitter.com/search?q=%23HTML5&src=hash">#HTML5</a> spec examples <a href="https://t.co/0FIEiYN1pC">https://t.co/0FIEiYN1pC</a></p><cite>— karl dubost (@karlpro) <a href="https://twitter.com/karlpro/statuses/370905307293442048">August 23, 2013</a></cite> </blockquote>
cite
element is used to reference the title of a work in a
bibliography:
<p><cite>Universal Declaration of Human Rights</cite>, United Nations, December 1948. Adopted by General Assembly resolution 217 A (III).</p>
cite
element is used to reference the title of a television
show:
<p>Who is your favorite doctor (in <cite>Doctor Who</cite>)?</p>
cite
element is to identify the author of a comment in a
blog post or forum, as in this example:
<article id="comment-1"> Comment by <cite><a href="https://oli.jp">Oli Studholme</a></cite> <time datetime="2013-08-19T16:01">August 19th, 2013 at 4:01 pm</time> <p>Unfortunately I don’t think adding names back into the definition of <code>cite</code> solves the problem: of the 12 blockquote examples in <a href="https://oli.jp/example/blockquote-metadata/">Examples of block quote metadata</a>, there’s not even one that’s <em>just</em> a person’s name.</p> <p>A subset of the problem, maybe…</p> </article>
cite
element is to reference the URL
of a search result, as in this example:
<div id="resultStats">About 416,000,000 results 0.33 seconds) </div> ... <p><a href="https://www.w3.org/html/wg/">W3C <i>HTML Working Group</i></a></p> <p><cite>www.w3.org/<b>html</b>/wg/</cite></p> <p>15 Apr 2013 - The <i>HTML Working Group</i> is currently chartered to continue its work through 31 December 2014. A Plan 2014 document published by the...</p> ...
cite
element is used to identify an abbreviated reference such as Ibid. it is suggested that this reference be linked to the base reference:
<article> <h2>Book notes</h2> ... ... <blockquote>"Money is the real cause of poverty," <footer> <cite id="baseref">The Ragged-Trousered Philanthropists, page 89.</cite> </footer> </blockquote> ... ... <blockquote>"Money is the cause of poverty because it is the device by which those who are too lazy to work are enabled to rob the workers of the fruits of their labour." <a href="#baseref"><cite>Ibid.</cite></a> </blockquote> ... </article>
A citation is not a quote (for which the q
element is
appropriate).
cite
is not for quotes:
<p><cite>This is wrong!, said Hillary.</cite> is a quote from the popular daytime TV drama When Ian became Hillary.</p>
This is an example of the correct usage:
<p><q>This is correct, said Hillary.</q> is a quote from the popular daytime TV drama <cite>When Ian became Hillary</cite>.</p>
4.5.7. The q
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
cite
- Link to the source of the quotation or more information about the edit - Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLQuoteElement
.
The q
element represents some phrasing content quoted from another
source.
Quotation punctuation (such as quotation marks) that is quoting the contents of the element must
not appear immediately before, after, or inside q
elements; they will be inserted
into the rendering by the user agent.
Content inside a q
element must be quoted from another source, whose address, if it
has one, may be cited in the cite
attribute. The source may be fictional,
as when quoting characters in a novel or screenplay.
If the cite
attribute is present, it must be a valid URL potentially surrounded by spaces. To obtain the corresponding citation link, the
value of the attribute must be parsed relative to the element’s node document.
User agents may allow users to follow such citation links, but they are primarily intended for
private use (e.g., by server-side scripts collecting statistics about a site’s use of quotations),
not for readers.
The q
element must not be used in place of quotation marks that do not represent
quotes; for example, it is inappropriate to use the q
element for marking up
sarcastic statements.
The use of q
elements to mark up quotations is entirely optional; using explicit
quotation punctuation without q
elements is just as correct.
q
element:
<p>The man said <q>Things that are impossible just take longer</q>. I disagreed with him.</p>
q
element, and an
explicit citation outside:
<p>The W3C page <cite>About W3C</cite> says the W3C’s mission is <q cite="https://www.w3.org/Consortium/">To lead the World Wide Web to its full potential by developing protocols and guidelines that ensure long-term growth for the Web</q>. I disagree with this mission.</p>
<p>In <cite>Example One</cite>, he writes <q>The man said <q>Things that are impossible just take longer</q>. I disagreed with him</q>. Well, I disagree even more!</p>
q
element:
<p>His best argument was ❝I disagree❞, which I thought was laughable.</p>
q
element in this case would be inappropriate.
<p>The word "ineffable" could have been used to describe the disaster resulting from the campaign’s mismanagement.</p>
4.5.8. The dfn
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content, but there must be no
dfn
element descendants. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Also, the
title
attribute has special semantics on this element. - Also, the
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The dfn
element represents the defining instance of a term. The paragraph, description list group, or section that is the nearest ancestor of
the dfn
element must also contain the definition(s) for the term given by the dfn
element.
Defining term: If the dfn
element has a title
attribute, then the exact value of that attribute is the term being defined. Otherwise, if it
contains exactly one element child node and no child Text
nodes, and that child
element is an abbr
element with a title
attribute, then the exact value
of that attribute is the term being defined. Otherwise, it is the exact textContent
of the dfn
element that gives the term being defined.
If the title
attribute of the dfn
element is present, then it must
contain only the term being defined.
The title
attribute of ancestor elements does not affect dfn
elements.
An a
element that links to a dfn
element represents an instance of the
term defined by the dfn
element.
<p>The <dfn><abbr title="Garage Door Opener">GDO</abbr></dfn> is a device that allows off-world teams to open the iris.</p> <!-- ... later in the document: --> <p>Teal’c activated his <abbr title="Garage Door Opener">GDO</abbr> and so Hammond ordered the iris to be opened.</p>
With the addition of an a
element, the reference can be made explicit:
<p>The <dfn id=gdo><abbr title="Garage Door Opener">GDO</abbr></dfn> is a device that allows off-world teams to open the iris.</p> <!-- ... later in the document: --> <p>Teal’c activated his <a href=#gdo><abbr title="Garage Door Opener">GDO</abbr></a> and so Hammond ordered the iris to be opened.</p>
4.5.9. The abbr
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Also, the
title
attribute has special semantics on this element. - Also, the
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The abbr
element represents an abbreviation or acronym, optionally with its
expansion. The title
attribute may be used to provide an expansion of the
abbreviation. The attribute, if specified, must contain an expansion of the abbreviation, and
nothing else.
abbr
element.
This paragraph defines the term "Web Hypertext Application
Technology Working Group".
<p>The <dfn id=whatwg><abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr></dfn> is a loose unofficial collaboration of Web browser manufacturers and interested parties who wish to develop new technologies designed to allow authors to write and deploy Applications over the World Wide Web.</p>
An alternative way to write this would be:
<p>The <dfn id=whatwg>Web Hypertext Application Technology Working Group</dfn> (<abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr>) is a loose unofficial collaboration of Web browser manufacturers and interested parties who wish to develop new technologies designed to allow authors to write and deploy Applications over the World Wide Web.</p>
abbr
element.
<p>The <abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr> started working on HTML in 2004.</p>
<p>The <a href="#whatwg"><abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr></a> community does not have much representation from Asia.</p>
<p>Philip and Dashiva both denied that they were going to get the issue counts from past revisions of the specification to backfill the <abbr>WHATWG</abbr> issue graph.</p>
If an abbreviation is pluralized, the expansion’s grammatical number (plural vs singular) must match the grammatical number of the contents of the element.
<p>Two <abbr title="Working Group">WG</abbr>s worked on this specification: the <abbr>WHATWG</abbr> and the <abbr>HTMLWG</abbr>.</p>
Here the plural is inside the element, so the expansion is in the plural:
<p>Two <abbr title="Working Groups">WGs</abbr> worked on this specification: the <abbr>WHATWG</abbr> and the <abbr>HTMLWG</abbr>.</p>
Abbreviations do not have to be marked up using this element. It is expected to be useful in the following cases:
-
Abbreviations for which the author wants to give expansions, where using the
abbr
element with atitle
attribute is an alternative to including the expansion inline (e.g., in parentheses). -
Abbreviations that are likely to be unfamiliar to the document’s readers, for which authors are encouraged to either mark up the abbreviation using an
abbr
element with atitle
attribute or include the expansion inline in the text the first time the abbreviation is used. -
Abbreviations whose presence needs to be semantically annotated, e.g., so that they can be identified from a style sheet and given specific styles, for which the
abbr
element can be used without atitle
attribute.
Providing an expansion in a title
attribute once will not necessarily cause other abbr
elements in the same document with the same contents but without a title
attribute to behave as if they had the same expansion. Every abbr
element is independent.
4.5.10. The ruby
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- See prose.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The ruby
element allows one or more spans of phrasing content to be marked with ruby
annotations. Ruby annotations are short runs of text presented alongside base text, primarily
used in East Asian typography as a guide for pronunciation or to include other annotations. In
Japanese, this form of typography is also known as furigana. Ruby text can appear on either
side, and sometimes both sides, of the base text, and it is possible to control its position using
CSS. A more complete introduction to ruby can be found in the Use Cases & Exploratory
Approaches for Ruby Markup document as well as in CSS Ruby. [RUBY-UC] [CSS3-RUBY]
The content model of ruby
elements consists of one or more of the following sequences:
-
One or more phrasing content nodes or
rb
elements. -
One or more
rt
orrtc
elements, each of which either immediately preceded or followed by anrp
elements.
The ruby
, rb
, rtc
, and rt
elements can be used
for a variety of kinds of annotations, including in particular (though by no means limited to)
those described below. For more details on Japanese Ruby in particular, and how to render Ruby for
Japanese, see Requirements for Japanese Text Layout. [JLREQ] The rp
element can be used as fallback content when ruby rendering is not supported.
-
Mono-ruby for individual base characters
-
Annotations (the ruby text) are associated individually with each ideographic character (the base text). In Japanese this is typically hiragana or katakana characters used to provide readings of kanji characters.
When no
rb
element is used, the base is implied, as above. But you can also make it explicit. This can be useful notably for styling, or when consecutive bases are to be treated as a group, as in the jukugo ruby example further down.In the following example, notice how each annotation corresponds to a single base character.
<ruby>日<rt>に</rt></ruby><ruby>本<rt>ほん</rt></ruby> <ruby>語<rt>ご</rt></ruby>で<ruby>書<rt>か</rt></ruby> いた<ruby>作<rt>さく</rt></ruby><ruby>文<rt>ぶん</rt></ruby>です。
Ruby text interspersed in regular text provides structure akin to the following image:
This example can also be written as follows, using one
ruby
element with two segments of base text and two annotations (one for each) rather than two back-to-backruby
elements each with one base text segment and annotation (as in the markup above):<ruby>日<rt>に</rt>本<rt>ほん</rt>語<rt>ご</rt></ruby> で<ruby>書<rt>か</rt></ruby> いた<ruby>作<rt>さく</rt>文<rt>ぶん</rt></ruby>です。
-
Group ruby
-
Group ruby is often used where phonetic annotations don’t map to discreet base characters, or for semantic glosses that span the whole base text. For example, the word "today" is written with the characters 今日, literally "this day". But it’s pronounced きょう (kyou), which can’t be broken down into a "this" part and a "day" part. In typical rendering, you can’t split text that is annotated with group ruby; it has to wrap as a single unit onto the next line. When a ruby text annotation maps to a base that is comprised of more than one character, then that base is grouped.
The following group ruby:
Can be marked up as follows:
-
Jukugo ruby
-
Jukugo refers to a Japanese compound noun, i.e., a word made up of more than one kanji character. Jukugo ruby is a term that is used not to describe ruby annotations over jukugo text, but rather to describe ruby with a behavior slightly different from mono or group ruby. Jukugo ruby is similar to mono ruby, in that there is a strong association between ruby text and individual base characters, but the ruby text is typically rendered as grouped together over multiple ideographs when they are on the same line.
The distinction is captured in this example:
Which can be marked up as follows:
In this example, each
rt
element is paired with its respectiverb
element, the difference with an interleavedrb
/rt
approach being that the sequences of both base text and ruby annotations are implicitly placed in common containers so that the grouping information is captured.For more details on Jukugo Ruby rendering, see Appendix F in the Requirements for Japanese Text Layout and Use Case C: Jukugo ruby in the Use Cases & Exploratory Approaches for Ruby Markup. [JLREQ] [RUBY-UC]
-
Inline ruby
-
In some contexts, for instance when the font size or line height are too small for ruby to be readable, it is desirable to inline the ruby annotation such that it appears in parentheses after the text it annotates. This also provides a convenient fallback strategy for user agents that do not support rendering ruby annotations.
Inlining takes grouping into account. For example, Tokyo is written with two kanji characters, 東, which is pronounced とう, and 京, which is pronounced きょう. Each base character should be annotated individually, but the fallback should be 東京(とうきょう) not 東(とう)京(きょう). This can be marked up as follows:
Note that the above markup will enable the usage of parentheses when inlining for browsers that support ruby layout, but for those that don’t it will fail to provide parenthetical fallback. This is where the
rp
element is useful. It can be inserted into the above example to provide the appropriate fallback when ruby layout is not supported:
-
Text with both phonetic and semantic annotations (double-sided ruby)
-
Sometimes, ruby can be used to annotate a base twice.
In the following example, the Chinese word for San Francisco (旧金山, i.e., "old gold mountain") is annotated both using pinyin to give the pronunciation, and with the original English.
Which is marked up as follows:
In this example, a single base run of three base characters is annotated with three pinyin ruby text segments in a first (implicit) container, and an
rtc
element is introduced in order to provide a second single ruby text annotation being the city’s English name.We can also revisit our jukugo example above with 上手 ("skill") to show how it can be annotation in both kana and romaji phonetics while at the same time maintaining the pairing to bases and annotation grouping information.
Which is marked up as follows:
Text that is a direct child of the
rtc
element implicitly produces a ruby text segment as if it were contained in anrt
element. In this contrived example, this is shown with some symbols that are given names in English and French with annotations intended to appear on either side of the base symbol.<ruby> ♥<rt>Heart<rtc lang=fr>Cœur</rtc> ☘<rt>Shamrock<rtc lang=fr>Trèfle</rtc> ✶<rt>Star<rtc lang=fr>Étoile </ruby>
Similarly, text directly inside a
ruby
element implicitly produces a ruby base as if it were contained in anrb
element, andrt
children ofruby
are implicitly contained in anrtc
container. In effect, the above example is equivalent (in meaning, though not in the DOM it produces) to the following:
-
-
Zero or more ruby bases, each of which is a DOM range that may contain phrasing content or an
rb
element. -
A base range, that is a DOM range including all the bases. This is the ruby base container.
-
Zero or more ruby text containers which may correspond to explicit
rtc
elements, or to sequences ofrt
elements implicitly recognized as contained in an anonymous ruby text container.
Each ruby text container is described by zero or more ruby text annotations each of which is a DOM range that may contain phrasing content
or an rt
element, and an annotations range that is a range including all the
annotations for that container. A ruby text container is also known (primarily in a CSS
context) as a ruby annotation container.
Furthermore, a ruby element contains ignored ruby content. Ignored ruby content does
not form part of the document’s semantics. It consists of some inter-element whitespace and rp
elements, the latter of which are used for legacy user agents that do not
support ruby at all.
The process of annotation pairing associates ruby annotations with ruby bases. Within each ruby segment, each ruby base in the ruby base container is paired with one ruby text annotation from the ruby text container, in order. If there are not enough ruby text annotations in a ruby annotation container, the last one is associated with any excess ruby bases. (If there are not any in the ruby annotation container, an anonymous empty one is assumed to exist.) If there are not enough ruby bases, any remaining ruby text annotations are assumed to be associated with empty, anonymous bases inserted at the end of the ruby base container.
Note that the terms ruby segment, ruby base, ruby text annotation, ruby text container, ruby base container, and ruby annotation container have their equivalents in CSS Ruby Module Level 3. [CSS3-RUBY]
Informally, the segmentation and categorization algorithm below performs a simple set of
tasks. First it processes adjacent rb
elements, text nodes, and non-ruby
elements into a list of bases. Then it processes any number of rtc
elements or
sequences of rt
elements that are considered to automatically map to an
anonymous ruby text container. Put together these data items form a ruby
segment as detailed in the data model above. It will continue to produce such segments
until it reaches the end of the content of a given ruby
element. The complexity
of the algorithm below compared to this informal description stems from the need to support
an author-friendly syntax and being mindful of inter-element white space.
At any particular time, the segmentation and categorization of content of a ruby
element is the result that would be obtained from running the following
algorithm:
- Let root be the
ruby
element for which the algorithm is being run. - Let index be 0.
- Let ruby segments be an empty list.
- Let current bases be an empty list of DOM ranges.
- Let current bases range be null.
- Let current bases range start be null.
- Let current annotations be an empty list of DOM ranges.
- Let current annotations range be null.
- Let current annotations range start be null.
- Let current annotation containers be an empty list.
- Let current automatic base nodes be an empty list of DOM Nodes.
- Let current automatic base range start be null.
- Process a ruby child: If index is equal to or greater than the number of child nodes in root, then run the steps to commit a ruby segment, return ruby segments, and abort these steps.
- Let current child be the indexth node in root.
- If current child is not a Text node and is not an
Element
node, then increment index by one and jump to the step labelled process a ruby child. - If current child is an
rp
element, then increment index by one and jump to the step labelled process a ruby child. (Note that this has the effect of including this element in any range that we are currently processing. This is done intentionally so that misplacedrp
can be processed correctly; semantically they are ignored all the same.) -
If current child is an
rt
element, then run these substeps:- Run the steps to commit an automatic base.
- Run the steps to commit the base range.
- If current annotations is empty, set current annotations range start to the value of index.
- Create a new DOM range whose start is the boundary point (root, index) and whose end is the boundary point (root, index plus one), and append it at the end of current annotations.
- Increment index by one and jump to the step labelled process a ruby child.
-
If current child is an
rtc
element, then run these substeps:- Run the steps to commit an automatic base.
- Run the steps to commit the base range.
- Run the steps to commit current annotations.
- Create a new ruby annotation container. It is described by the list of
annotations returned by running the steps to process an
rtc
element and a DOM range whose start is the boundary point (root, index) and whose end is the boundary point (root, index plus one). Append this new ruby annotation container at the end of current annotation containers. - Increment index by one and jump to the step labelled process a ruby child.
-
If current child is a
Text
node and is inter-element whitespace, then run these substeps:- If current annotations is not empty, increment index by one and jump to the step labelled process a ruby child.
-
Run the following substeps:
- Let lookahead index be set to the value of index.
- Peek ahead: Increment lookahead index by one.
- If lookahead index is equal to or greater than the number of child nodes in root, then abort these substeps.
- Let peek child be the lookahead indexth node in root.
- If peek child is a
Text
node and is inter-element whitespace, then jump to the step labelled peek ahead. - If peek child is an
rt
element, anrtc
element, or anrp
element, then set index to the value of lookahead index and jump to the step labelled process a ruby child.
- If current annotations is not empty or if current annotation containers is not empty, then run the steps to commit a ruby segment.
-
If current child is an
rb
element, then run these substeps:- Run the steps to commit an automatic base.
- If current bases is empty, then set current bases range start to the value of index.
- Create a new DOM range whose start is the boundary point (root, index) and whose end is the boundary point (root, index plus one), and append it at the end of current bases.
- Increment index by one and jump to the step labelled process a ruby child.
- If current automatic base nodes is empty, set current automatic base range start to the value of index.
- Append current child at the end of current automatic base nodes.
- Increment index by one and jump to the step labelled process a ruby child.
When the steps above say to commit a ruby segment, it means to run the following steps at that point in the algorithm:
- Run the steps to commit an automatic base.
- If current bases, current annotations, and current annotation containers are all empty, abort these steps.
- Run the steps to commit the base range.
- Run the steps to commit current annotations.
- Create a new ruby segment. It is described by a list of bases set to current bases, a base DOM range set to current bases range, and a list of ruby annotation containers that are the current annotation containers list. Append this new ruby segment at the end of ruby segments.
- Let current bases be an empty list.
- Let current bases range be null.
- Let current bases range start be null.
- Let current annotation containers be an empty list.
When the steps above say to commit the base range, it means to run the following steps at that point in the algorithm:
- If current bases is empty, abort these steps.
- If current bases range is not null, abort these steps.
- Let current bases range be a DOM range whose start is the boundary point (root, current bases range start) and whose end is the boundary point (root, index).
When the steps above say to commit current annotations, it means to run the following steps at that point in the algorithm:
- If current annotations is not empty and current annotations range is null let current annotations range be a DOM range whose start is the boundary point (root, current annotations range start) and whose end is the boundary point (root, index).
- If current annotations is not empty, create a new ruby annotation container. It is described by an annotations list set to current annotations and a range set to current annotations range. Append this new ruby annotation container at the end of current annotation containers.
- Let current annotations be an empty list of DOM ranges.
- Let current annotations range be null.
- Let current annotations range start be null.
When the steps above say to commit an automatic base, it means to run the following steps at that point in the algorithm:
- If current automatic base nodes is empty, abort these steps.
-
If current automatic base nodes contains nodes that are not
Text
nodes, orText
nodes that are not inter-element whitespace, then run these substeps:- It current bases is empty, set current bases range start to the value of current automatic base range start.
- Create a new DOM range whose start is the boundary point (root, current automatic base range start) and whose end is the boundary point (root, index), and append it at the end of current bases.
- Let current automatic base nodes be an empty list of DOM Nodes.
- Let current automatic base range start be null.
4.5.11. The rb
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
ruby
element. - Content model:
- Phrasing content.
- Tag omission in text/html:
- An
rb
element’s end tag may be omitted if therb
element is immediately followed by anrb
,rt
,rtc
orrp
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The rb
element marks the base text component of a ruby annotation. When it is
the child of a ruby
element, it doesn’t represent anything itself, but its parent ruby
element uses it as part of determining what it represents.
4.5.12. The rt
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
ruby
or of anrtc
element. - Content model:
- Phrasing content.
- Tag omission in text/html:
- An
rt
element’s end tag may be omitted if thert
element is immediately followed by anrb
,rt
,rtc
orrp
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The rt
element marks the ruby text component of a ruby annotation. When it is
the child of a ruby
element or of an rtc
element that is itself
the child of a ruby
element, it doesn’t represent anything itself, but its ancestor ruby
element uses it as part of determining what it represents.
rt
element that is not a child of a ruby
element or of an rtc
element that is itself the child of a ruby
element represents the same thing as its children. 4.5.13. The rtc
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
ruby
element. - Content model:
- Phrasing content,
rt
, orrp
elements. - Tag omission in text/html:
- An
rtc
element’s end tag may be omitted if thertc
element is immediately followed by anrb
orrtc
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The rtc
element marks a ruby text container for ruby text components
in a ruby annotation. When it is the child of a ruby
element it doesn’t represent anything itself, but its parent ruby
element
uses it as part of determining what it represents.
An rtc
element that is not a child of a ruby
element represents the same thing as its children.
When an rtc
element is processed as part of the segmentation and
categorization of content for a ruby
element, the following algorithm
defines how to process an rtc
element:
- Let root be the
rtc
element for which the algorithm is being run. - Let index be 0.
- Let annotations be an empty list of DOM ranges.
- Let current automatic annotation nodes be an empty list of DOM nodes.
- Let current automatic annotation range start be null.
- Process an rtc child: If index is equal to or greater than the number of child nodes in root, then run the steps to commit an automatic annotation, return annotations, and abort these steps.
- Let current child be the indexth node in root.
-
If current child is an
rt
element, then run these substeps:- Run the steps to commit an automatic annotation.
- Create a new DOM range whose start is the boundary point (root, index) and whose end is the boundary point (root, index plus one), and append it at the end of annotations.
- Increment index by one and jump to the step labelled process an rtc child.
- If current automatic annotation nodes is empty, set current automatic annotation range start to the value of index.
- Append current child at the end of current automatic annotation nodes.
- Increment index by one and jump to the step labelled process an rtc child.
When the steps above say to commit an automatic annotation, it means to run the following steps at that point in the algorithm:
- If current automatic annotation nodes is empty, abort these steps.
- If current automatic annotation nodes contains nodes that are not
Text
nodes, orText
nodes that are not inter-element whitespace, then create a new DOM range whose start is the boundary point (root, current automatic annotation range start) and whose end is the boundary point (root, index), and append it at the end of annotations. - Let current automatic annotation nodes be an empty list of DOM nodes.
- Let current automatic annotation range start be null.
4.5.14. The rp
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
ruby
orrtc
element, either immediately before or immediately after anrt
orrtc
element, but not betweenrt
elements. - Content model:
- Phrasing content.
- Tag omission in text/html:
- An
rp
element’s end tag may be omitted if therp
element is immediately followed by anrb
,rt
,rtc
orrp
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The rp
element is used to provide fallback text to be shown by user agents that
don’t support ruby annotations. One widespread convention is to provide parentheses around
the ruby text component of a ruby annotation.
The contents of the rp
elements are typically not displayed by user agents
which do support ruby annotations
An rp
element that is a child of a ruby
element represents nothing. An rp
element whose parent element is not a ruby
element represents its
children.
The example shown previously, in which each ideograph in the text 漢字 is annotated with its phonetic reading, could be expanded
to use rp
so that in legacy user agents the readings are in parentheses (please
note that white space has been introduced into this example in order to make it more
readable):
In conforming user agents the rendering would be as above, but in user agents that do not support ruby, the rendering would be:
When there are multiple annotations for a segment, rp
elements can also be
placed between the annotations. Here is another copy of an earlier contrived example showing
some symbols with names given in English and French using double-sided annotations, but this
time with rp
elements as well:
<ruby> ♥<rp>: </rp><rt>Heart</rt><rp>, </rp><rtc><rt lang=fr>Cœur</rt></rtc><rp>.</rp> ☘<rp>: </rp><rt>Shamrock</rt><rp>, </rp><rtc><rt lang=fr>Trèfle</rt></rtc><rp>.</rp> ✶<rp>: </rp><rt>Star</rt><rp>, </rp><rtc><rt lang=fr>Étoile</rt></rtc><rp>.</rp> </ruby>
This would make the example render as follows in non-ruby-capable user agents:
4.5.15. The data
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
value
- Machine-readable value - Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLDataElement : HTMLElement { attribute DOMString value; };
The data
element represents its contents, along with a
machine-readable form of those contents in the value
attribute.
The value
attribute must be present. Its value
must be a representation of the element’s contents in a machine-readable format.
When the value is date- or time-related, the more specific time
element can be used instead.
The element can be used for several purposes.
When combined with microformats or microdata,
the element serves to provide both a machine-readable value for the purposes
of data processors, and a human-readable value for the purposes of rendering in a Web browser. In
this case, the format to be used in the value
attribute is
determined by the microformats or microdata vocabulary in use.
The element can also, however, be used in conjunction with scripts in the page, for when a
script has a literal value to store alongside a human-readable value. In such cases, the format to
be used depends only on the needs of the script. (The data-*
attributes can also be useful in such situations.)
The value
IDL attribute must reflect the content attribute of the same name.
4.5.16. The time
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- If the element has a
datetime
attribute: Phrasing content.- Otherwise: Text , but must match requirements described in prose below.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
datetime
- Machine-readable value - Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLTimeElement : HTMLElement { attribute DOMString dateTime; };
The time
element represents its contents, along with a
machine-readable form of those contents in the datetime
attribute. The kind of content is limited to various kinds of dates, times, time-zone offsets, and
durations, as described below.
The datetime
attribute may be present. If
present, its value must be a representation of the element’s contents in a machine-readable
format.
A time
element that does not have a datetime
content attribute must not have any element
descendants.
The datetime value of a time
element is the value of the element’s datetime
content attribute, if it has one, otherwise the concatenation of the contents of
all the Text
nodes that are children of the time
element (ignoring any other
nodes such as comments or elements), in tree order.
The datetime value of a time
element must match one of the following
syntaxes.
- A valid month string
-
<time>2011-11</time>
- A valid date string
-
<time>2011-11-18</time>
- A valid yearless date string
-
<time>11-18</time>
- A valid time string
-
<time>14:54</time>
<time>14:54:39</time>
<time>14:54:39.929</time>
- A valid floating date and time string
-
<time>2011-11-18T14:54</time>
<time>2011-11-18T14:54:39</time>
<time>2011-11-18T14:54:39.929</time>
<time>2011-11-18 14:54</time>
<time>2011-11-18 14:54:39</time>
<time>2011-11-18 14:54:39.929</time>
Times with dates but without a time zone offset are useful for specifying events that are observed at the same specific time in each time zone, throughout a day. For example, the 2020 new year is celebrated at 2020-01-01 00:00 in each time zone, not at the same precise moment across all time zones. For events that occur at the same time across all time zones, for example a videoconference meeting, a valid global date and time string is likely more useful.
- A valid time-zone offset string
-
<time>Z</time>
<time>+0000</time>
<time>+00:00</time>
<time>-0800</time>
<time>-08:00</time>
For times without dates (or times referring to events that recur on multiple dates), specifying the geographic location that controls the time is usually more useful than specifying a time zone offset, because geographic locations change time zone offsets with daylight savings time. In some cases, geographic locations even change time zone, e.g., when the boundaries of those time zones are redrawn, as happened with Samoa at the end of 2011. There exists a time zone database that describes the boundaries of time zones and what rules apply within each such zone, known as the time zone database. [TZDATABASE]
- A valid global date and time string
-
<time>2011-11-18T14:54Z</time>
<time>2011-11-18T14:54:39Z</time>
<time>2011-11-18T14:54:39.929Z</time>
<time>2011-11-18T14:54+0000</time>
<time>2011-11-18T14:54:39+0000</time>
<time>2011-11-18T14:54:39.929+0000</time>
<time>2011-11-18T14:54+00:00</time>
<time>2011-11-18T14:54:39+00:00</time>
<time>2011-11-18T14:54:39.929+00:00</time>
<time>2011-11-18T06:54-0800</time>
<time>2011-11-18T06:54:39-0800</time>
<time>2011-11-18T06:54:39.929-0800</time>
<time>2011-11-18T06:54-08:00</time>
<time>2011-11-18T06:54:39-08:00</time>
<time>2011-11-18T06:54:39.929-08:00</time>
<time>2011-11-18 14:54Z</time>
<time>2011-11-18 14:54:39Z</time>
<time>2011-11-18 14:54:39.929Z</time>
<time>2011-11-18 14:54+0000</time>
<time>2011-11-18 14:54:39+0000</time>
<time>2011-11-18 14:54:39.929+0000</time>
<time>2011-11-18 14:54+00:00</time>
<time>2011-11-18 14:54:39+00:00</time>
<time>2011-11-18 14:54:39.929+00:00</time>
<time>2011-11-18 06:54-0800</time>
<time>2011-11-18 06:54:39-0800</time>
<time>2011-11-18 06:54:39.929-0800</time>
<time>2011-11-18 06:54-08:00</time>
<time>2011-11-18 06:54:39-08:00</time>
<time>2011-11-18 06:54:39.929-08:00</time>
Times with dates and a time zone offset are useful for specifying specific events, or recurring virtual events where the time is not anchored to a specific geographic location. For example, the precise time of an asteroid impact, or a particular meeting in a series of meetings held at 1400 UTC every day, regardless of whether any particular part of the world is observing daylight savings time or not. For events where the precise time varies by the local time zone offset of a specific geographic location, a valid floating date and time string combined with that geographic location is likely more useful.
- A valid week string
-
<time>2011-W47</time>
- Four or more ASCII digits, at least one of which is not U+0030 DIGIT ZERO (0)
-
<time>2011</time>
<time>0001</time>
- A valid duration string
-
<time>PT4H18M3S</time>
<time>4h 18m 3s</time>
Many of the preceding valid syntaxes describe "floating" date and/or time values (they do not include a time-zone offset). Care is needed when converting floating time values to or from global ("incremental") time values (e.g., JavaScript’s Date object). In many cases, an implicit time-of-day and time zone are used in the conversion and may result in unexpected changes to the value of the date itself. [TIMEZONE]
The machine-readable equivalent of the element’s contents must be obtained from the element’s datetime value by using the following algorithm:
- If parsing a month string from the element’s datetime value returns a month, that is the machine-readable equivalent; abort these steps.
- If parsing a date string from the element’s datetime value returns a date, that is the machine-readable equivalent; abort these steps.
- If parsing a yearless date string from the element’s datetime value returns a yearless date, that is the machine-readable equivalent; abort these steps.
- If parsing a time string from the element’s datetime value returns a time, that is the machine-readable equivalent; abort these steps.
- If parsing a floating date and time string from the element’s datetime value returns a floating date and time, that is the machine-readable equivalent; abort these steps.
- If parsing a time-zone offset string from the element’s datetime value returns a time-zone offset, that is the machine-readable equivalent; abort these steps.
- If parsing a floating date and time string from the element’s datetime value returns a global date and time, that is the machine-readable equivalent; abort these steps.
- If parsing a week string from the element’s datetime value returns a week, that is the machine-readable equivalent; abort these steps.
- If the element’s datetime value consists of only ASCII digits, at least one of which is not U+0030 DIGIT ZERO (0), then the machine-readable equivalent is the base-ten interpretation of those digits, representing a year; abort these steps.
- If parsing a duration string from the element’s datetime value returns a duration, that is the machine-readable equivalent; abort these steps.
- There is no machine-readable equivalent.
The algorithms referenced above are intended to be designed such that for any arbitrary string s, only one of the algorithms returns a value. A more efficient approach might be to create a single algorithm that parses all these data types in one pass; developing such an algorithm is left as an exercise to the reader.
The dateTime
IDL attribute must reflect the element’s datetime
content
attribute.
time
element can be used to encode dates, for example in microformats. The
following shows a hypothetical way of encoding an event using a variant on hCalendar that uses
the time
element:
<div class="vevent"> <a class="url" href="https://www.web2con.com/">https://www.web2con.com/</a> <span class="summary">Web 2.0 Conference</span>: <time class="dtstart" datetime="2005-10-05">October 5</time> - <time class="dtend" datetime="2005-10-07">7</time>, at the <span class="location">Argent Hotel, San Francisco, CA</span> </div>
time
element to mark up a blog post’s publication date.
<article vocab="https://n.example.org/" typeof="rfc4287"> <h1 property="title">Big tasks</h1> <footer>Published <time property="published" datetime="2009-08-29">two days ago</time>.</footer> <p property="content">Today, I went out and bought a bike for my kid.</p> </article>
time
, this
time using the schema.org microdata vocabulary:
<article typeof="schema:BlogPosting"> <h1 property="schema:headline">Small tasks</h1> <footer>Published <time property="schema:datePublished" datetime="2009-08-30">yesterday</time>.</footer> <p property="schema:articleBody">I put a bike bell on his bike.</p> </article>
time
element is used to encode a date in the
ISO8601 format, for later processing by a script:
<p>Our first date was <time datetime="2006-09-23">a Saturday</time>.</p>
In this second snippet, the value includes a time:
<p>We stopped talking at <time datetime="2006-09-24T05:00-07:00">5am the next morning</time>.</p>
A script loaded by the page (and thus privy to the page’s internal convention of marking up
dates and times using the time
element) could scan through the page and look at all
the time
elements therein to create an index of dates and times.
Today is <time datetime="2011-11-18">Friday</time>.
Your next meeting is at <time datetime="2011-11-18T15:00-08:00">3pm</time>.
4.5.17. The code
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The code
element represents a fragment of computer code. This could
be an XML element name, a file name, a computer program, or any other string that a computer would
recognize.
There is no formal way to indicate the language of computer code being marked up. Authors who
wish to mark code
elements with the language used, e.g., so that syntax highlighting
scripts can use the right rules, can use the class
attribute, e.g.,
by adding a class prefixed with "language-
" to the element.
<p>The <code>code</code> element represents a fragment of computer code.</p> <p>When you call the <code>activate()</code> method on the <code>robotSnowman</code> object, the eyes glow.</p> <p>The example below uses the <code>begin</code> keyword to indicate the start of a statement block. It is paired with an <code>end</code> keyword, which is followed by the <code>.</code> punctuation character (full stop) to indicate the end of the program.</p>
pre
and code
elements.
<pre><code class="language-pascal">var i: Integer; begin i := 1; end.</code></pre>
A class is used in that example to indicate the language used.
See the pre
element for more details.
4.5.18. The var
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The var
element represents a variable. This could be an actual
variable in a mathematical expression or programming context, an identifier representing a
constant, a symbol identifying a physical quantity, a function parameter, or just be a term used
as a placeholder in prose.
<p>If there are <var>n</var> pipes leading to the ice cream factory then I expect at <em>least</em> <var>n</var> flavors of ice cream to be available for purchase!</p>
For mathematics, in particular for anything beyond the simplest of expressions, MathML is more
appropriate. However, the var
element can still be used to refer to specific
variables that are then mentioned in MathML expressions.
var
.
<figure> <math> <mi>a</mi> <mo>=</mo> <msqrt> <msup><mi>b</mi><mn>2</mn></msup> <mi>+</mi> <msup><mi>c</mi><mn>2</mn></msup> </msqrt> </math> <figcaption> Using Pythagoras' theorem to solve for the hypotenuse <var>a</var> of a triangle with sides <var>b</var> and <var>c</var> </figcaption> </figure>
var
element is used to mark the variables and constants in that equation:
<p>Then he turned to the blackboard and picked up the chalk. After a few moment’s thought, he wrote <var>E</var> = <var>m</var> <var>c</var><sup>2</sup>. The teacher looked pleased.</p>
4.5.19. The samp
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The samp
element represents sample or quoted output from another
program or computing system.
See the pre
and kbd
elements for more details.
This element can be contrasted with the output
element, which can be
used to provide immediate output in a Web application.
samp
element being used
inline:
<p>The computer said <samp>Too much cheese in tray two</samp> but I didn’t know what that meant.</p>
samp
and kbd
elements allow for the styling of specific elements of the sample output using a
style sheet. There’s also a few parts of the samp
that are annotated with even more
detailed markup, to enable very precise styling. To achieve this, span
elements are
used.
<pre><samp><span class="prompt">jdoe@mowmow:~$</span> <kbd>ssh demo.example.com</kbd> Last login: Tue Apr 12 09:10:17 2005 from mowmow.example.com on pts/1 Linux demo 2.6.10-grsec+gg3+e+fhs6b+nfs+gr0501+++p3+c4a+gr2b-reslog-v6.189 #1 SMP Tue Feb 1 11:22:36 PST 2005 i686 unknown <span class="prompt">jdoe@demo:~$</span> <span class="cursor">_</span></samp></pre>
4.5.20. The kbd
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The kbd
element represents user input (typically keyboard input,
although it may also be used to represent other input, such as voice commands).
When the kbd
element is nested inside a samp
element, it represents
the input as it was echoed by the system.
When the kbd
element contains a samp
element, it represents
input based on system output, for example invoking a menu item.
When the kbd
element is nested inside another kbd
element, it
represents an actual key or other single unit of input as appropriate for the input mechanism.
kbd
element is used to indicate keys to press:
<p>To make George eat an apple, press <kbd><kbd>Shift</kbd>+<kbd>F3</kbd></kbd></p>
In this second example, the user is told to pick a particular menu item. The outer kbd
element marks up a block of input, with the inner kbd
elements
representing each individual step of the input, and the samp
elements inside them
indicating that the steps are input based on something being displayed by the system, in this
case menu labels:
<p>To make George eat an apple, select <kbd><kbd><samp>File</samp></kbd>|<kbd><samp>Eat Apple...</samp></kbd></kbd> </p>
Such precision isn’t necessary; the following is equally fine:
<p>To make George eat an apple, select <kbd>File | Eat Apple...</kbd></p>
4.5.21. The sub
and sup
elements
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Use
HTMLElement
.
The sup
element represents a superscript and the sub
element represents a subscript.
These elements must be used only to mark up typographical conventions with specific meanings,
not for typographical presentation for presentation’s sake. For example, it would be inappropriate
for the sub
and sup
elements to be used in the name of the LaTeX
document preparation system. In general, authors should use these elements only if the absence of those elements would change the meaning of the content.
In certain languages, superscripts are part of the typographical conventions for some abbreviations.
<p>The most beautiful women are <span lang="fr"><abbr>M<sup>lle</sup></abbr> Gwendoline</span> and <span lang="fr"><abbr>M<sup>me</sup></abbr> Denise</span>.</p>
The sub
element can be used inside a var
element, for variables that
have subscripts.
sub
element is used to represent the subscript that identifies the
variable in a family of variables:
<p>The coordinate of the <var>i</var>th point is (<var>x<sub><var>i</var></sub></var>, <var>y<sub><var>i</var></sub></var>). For example, the 10th point has coordinate (<var>x<sub>10</sub></var>, <var>y<sub>10</sub></var>).</p>
Mathematical expressions often use subscripts and superscripts. Authors are encouraged to use
MathML for marking up mathematics, but authors may opt to use sub
and sup
if detailed mathematical markup is not desired. [MATHML]
<var>E</var>=<var>m</var><var>c</var><sup>2</sup>
f(<var>x</var>, <var>n</var>) = log<sub>4</sub><var>x</var><sup><var>n</var></sup>
4.5.22. The i
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The i
element represents a span of text in an alternate voice or
mood, or otherwise offset from the normal prose in a manner indicating a different quality of
text, such as a taxonomic designation, a technical term, an idiomatic phrase from another
language, transliteration, a thought, or a ship name in Western texts.
Terms in languages different from the main text should be annotated with lang
attributes (or, in XML, lang
attributes in the XML namespace).
i
element:
<p>The <i class="taxonomy">Felis silvestris catus</i> is cute.</p> <p>The term <i>prose content</i> is defined above.</p> <p>There is a certain <i lang="fr">je ne sais quoi</i> in the air.</p>
In the following example, a dream sequence is marked up using i
elements.
<p>Raymond tried to sleep.</p> <p><i>The ship sailed away on Thursday</i>, he dreamt. <i>The ship had many people aboard, including a beautiful princess called Carey. He watched her, day-in, day-out, hoping she would notice him, but she never did.</i></p> <p><i>Finally one night he picked up the courage to speak with her—</i></p> <p>Raymond woke with a start as the fire alarm rang out.</p>
Authors can use the class
attribute on the i
element to identify why the element is being used, so that if the style of a particular use (e.g.,
dream sequences as opposed to taxonomic terms) is to be changed at a later date, the author
doesn’t have to go through the entire document (or series of related documents) annotating each
use.
Authors are encouraged to consider whether other elements might be more applicable than the i
element, for instance the em
element for marking up stress emphasis,
or the dfn
element to mark up the defining instance of a term.
Style sheets can be used to format i
elements, just like any other
element can be restyled. Thus, it is not the case that content in i
elements will
necessarily be italicized.
4.5.23. The b
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The b
element represents a span of text to which attention is being
drawn for utilitarian purposes without conveying any extra importance and with no implication of
an alternate voice or mood, such as key words in a document abstract, product names in a review,
actionable words in interactive text-driven software, or an article lede.
b
element to highlight key words without
marking them up as important:
<p>The <b>frobonitor</b> and <b>barbinator</b> components are fried.</p>
b
element.
<p>You enter a small room. Your <b>sword</b> glows brighter. A <b>rat</b> scurries past the corner wall.</p>
b
element is appropriate is in marking up the lede (or
lead) sentence or paragraph. The following example shows how a BBC article about
kittens adopting a rabbit as their own could be marked up:
<article> <h2>Kittens 'adopted' by pet rabbit</h2> <p><b class="lede">Six abandoned kittens have found an unexpected new mother figure — a pet rabbit.</b></p> <p>Veterinary nurse Melanie Humble took the three-week-old kittens to her Aberdeen home.</p> [...]
As with the i
element, authors can use the class
attribute on the b
element to identify why the element is being used, so that if the
style of a particular use is to be changed at a later date, the author doesn’t have to go through
annotating each use.
The b
element should be used as a last resort when no other element is more
appropriate. In particular, headings should use the h1
to h6
elements,
stress emphasis should use the em
element, importance should be denoted with the strong
element, and text marked or highlighted should use the mark
element.
<p><b>WARNING!</b> Do not frob the barbinator!</p>
In the previous example, the correct element to use would have been strong
, not b
.
Style sheets can be used to format b
elements, just like any other
element can be restyled. Thus, it is not the case that content in b
elements will
necessarily be boldened.
4.5.24. The u
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The u
element represents a span of text with an unarticulated, though
explicitly rendered, non-textual annotation, such as labeling the text as being a proper name in
Chinese text (a Chinese proper name mark), or labeling the text as being misspelt.
In most cases, another element is likely to be more appropriate: for marking stress emphasis,
the em
element should be used; for marking key words or phrases either the b
element or the mark
element should be used, depending on the context;
for marking book titles, the cite
element should be used; for labeling text with explicit textual annotations, the ruby
element should be used; for technical terms, taxonomic designation,
transliteration, a thought, or for labeling ship names in Western texts, the i
element should be used.
The default rendering of the u
element in visual presentations
clashes with the conventional rendering of hyperlinks (underlining). Authors are encouraged to
avoid using the u
element where it could be confused for a hyperlink.
4.5.25. The mark
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The mark
element represents a run of text in one document marked or
highlighted for reference purposes, due to its relevance in another context. When used in a
quotation or other block of text referred to from the prose, it indicates a highlight that was not
originally present but which has been added to bring the reader’s attention to a part of the text
that might not have been considered important by the original author when the block was originally
written, but which is now under previously unexpected scrutiny. When used in the main prose of a
document, it indicates a part of the document that has been highlighted due to its likely
relevance to the user’s current activity.
mark
element can be used to bring attention to a
particular part of a quotation:
<p lang="en-US">Consider the following quote:</p> <blockquote lang="en-GB"> <p>Look around and you will find, no-one’s really <mark>colour</mark> blind.</p> </blockquote> <p lang="en-US">As we can tell from the <em>spelling</em> of the word, the person writing this quote is clearly not American.</p>
(If the goal was to mark the element as misspelt, however, the u
element,
possibly with a class, would be more appropriate.)
mark
element is highlighting parts of a document that are
matching some search string. If someone looked at a document, and the server knew that the user
was searching for the word "kitten", then the server might return the document with one paragraph
modified as follows:
<p>I also have some <mark>kitten</mark>s who are visiting me these days. They’re really cute. I think they like my garden! Maybe I should adopt a <mark>kitten</mark>.</p>
<p>The highlighted part below is where the error lies:</p> <pre><code>var i: Integer; begin i := <mark>1.1</mark>; end.</code></pre>
This is separate from syntax highlighting, for which span
is more
appropriate. Combining both, one would get:
<p>The highlighted part below is where the error lies:</p> <pre><code><span class=keyword>var</span> <span class=ident>i</span>: <span class=type>Integer</span>; <span class=keyword>begin</span> <span class=ident>i</span> := <span class=literal><mark>1.1</mark></span>; <span class=keyword>end</span>.</code></pre>
mark
to highlight a part of quoted
text that was originally not emphasized. In this example, common typographic conventions have led
the author to explicitly style mark
elements in quotes to render in italics.
<head> <style> blockquote mark, q mark { font: inherit; font-style: italic; text-decoration: none; background: transparent; color: inherit; } .bubble em { font: inherit; font-size: larger; text-decoration: underline; } </style> </head> <article> <h1>She knew</h1> <p>Did you notice the subtle joke in the joke on panel 4?</p> <blockquote> <p class="bubble">I didn’t <em>want</em> to believe. <mark>Of course on some level I realized it was a known-plaintext attack.</mark> But I couldn’t admit it until I saw for myself.</p> </blockquote> <p>(Emphasis mine.) I thought that was great. It’s so pedantic, yet it explains everything neatly.</p> </article>
Note, incidentally, the distinction between the em
element in this example, which
is part of the original text being quoted, and the mark
element, which is
highlighting a part for comment.
strong
) as opposed to denoting the relevance of a span of text
(mark
). It is an extract from a textbook, where the extract has had the parts
relevant to the exam highlighted. The safety warnings, important though they may be, are
apparently not relevant to the exam.
<h3>Wormhole Physics Introduction</h3> <p><mark>A wormhole in normal conditions can be held open for a maximum of just under 39 minutes.</mark> Conditions that can increase the time include a powerful energy source coupled to one or both of the gates connecting the wormhole, and a large gravity well (such as a black hole).</p> <p><mark>Momentum is preserved across the wormhole. Electromagnetic radiation can travel in both directions through a wormhole, but matter cannot.</mark></p> <p>When a wormhole is created, a vortex normally forms. <strong>Warning: The vortex caused by the wormhole opening will annihilate anything in its path.</strong> Vortexes can be avoided when using sufficiently advanced dialing technology.</p> <p><mark>An obstruction in a gate will prevent it from accepting a wormhole connection.</mark></p>
4.5.26. The bdi
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Also, the
dir
global attribute has special semantics on this element. - Also, the
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The bdi
element represents a span of text that is to be isolated from
its surroundings for the purposes of bidirectional text formatting. [BIDI]
The dir
global attribute defaults to auto
on this element (it never inherits from the parent element like
with other elements).
In this example, usernames are shown along with the number of posts that the user has
submitted. If the bdi
element were not used, the username of the Arabic user would
end up confusing the text (the bidirectional algorithm would put the colon and the number "3"
next to the word "User" rather than next to the word "posts").
<ul> <li>User <bdi>jcranmer</bdi>: 12 posts. <li>User <bdi>hober</bdi>: 5 posts. <li>User <bdi>إيان</bdi>: 3 posts. </ul>
![](images/sample-bdi.png)
bdi
element, the username acts as expected.![](images/sample-not-bdi.png)
bdi
element were to be replaced by a b
element, the username would confuse the bidirectional algorithm and the third bullet would end up saying "User 3 :", followed by the Arabic name (right-to-left), followed by "posts" and a period.4.5.27. The bdo
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Also, the
dir
global attribute has special semantics on this element. - Also, the
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The bdo
element represents explicit text directionality formatting
control for its children. It allows authors to override the Unicode bidirectional algorithm by
explicitly specifying a direction override. [BIDI]
Authors must specify the dir
attribute on this element, with the
value ltr
to specify a left-to-right override and with the value rtl
to
specify a right-to-left override. The auto
value must not be specified.
4.5.28. The span
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLSpanElement : HTMLElement {};
The span
element doesn’t mean anything on its own, but can be useful when used
together with the Global attributes, e.g., class
, lang
, or dir
. It represents its children.
span
elements and class
attributes so that its keywords and
identifiers can be color-coded from CSS:
<pre><code class="lang-c"><span class="keyword">for</span> (<span class="ident">j</span> = 0; <span class="ident">j</span> < 256; <span class="ident">j</span>++) { <span class="ident">i_t3</span> = (<span class="ident">i_t3</span> & 0x1ffff) | (<span class="ident">j</span> << 17); <span class="ident">i_t6</span> = (((((((<span class="ident">i_t3</span> >> 3) ^ <span class="ident">i_t3</span>) >> 1) ^ <span class="ident">i_t3</span>) >> 8) ^ <span class="ident">i_t3</span>) >> 5) & 0xff; <span class="keyword">if</span> (<span class="ident">i_t6</span> == <span class="ident">i_t1</span>) <span class="keyword">break</span>; }</code></pre>
4.5.29. The br
element
- Categories:
- Flow content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLBRElement : HTMLElement {};
The br
element represents a line break.
While line breaks are usually represented in visual media by physically moving subsequent text to a new line, a style sheet or user agent would be equally justified in causing line breaks to be rendered in a different manner, for instance as green dots, or as extra spacing.
br
elements must be used only for line breaks that are actually part of the
content, as in poems or addresses.
br
element:
<p>P. Sherman<br> 42 Wallaby Way<br> Sydney</p>
br
elements must not be used for separating thematic groups in a paragraph.
br
element:
<p><a ...>34 comments.</a><br> <a ...>Add a comment.</a></p>
<p><label>Name: <input name="name"></label><br> <label>Address: <input name="address"></label></p>
Here are alternatives to the above, which are correct:
<p><a ...>34 comments.</a></p> <p><a ...>Add a comment.</a></p>
<p><label>Name: <input name="name"></label></p> <p><label>Address: <input name="address"></label></p>
If a paragraph consists of nothing but a single br
element, it
represents a placeholder blank line (e.g., as in a template). Such blank lines must not be used for
presentation purposes.
Any content inside br
elements must not be considered part of the surrounding
text.
This element has rendering requirements involving the bidirectional algorithm.
4.5.30. The wbr
element
- Categories:
- Flow content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The wbr
element represents a line break opportunity.
wbr
element.
<p>So then he pointed at the tiger and screamed "there<wbr>is<wbr>no<wbr>way<wbr>you<wbr>are<wbr>ever<wbr>going<wbr>to<wbr>catch<wbr>me"!</p>
wbr
elements.
<pre>... Heading heading = Helm.HeadingFactory(HeadingCoordinates[1], <wbr>HeadingCoordinates[2], <wbr>HeadingCoordinates[3], <wbr>HeadingCoordinates[4]); Course course = Helm.CourseFactory(Heading, <wbr>Maps.MapFactoryFromHeading(heading), <wbr>Speeds.GetMaximumSpeed().ConvertToWarp()); ...</pre>
Any content inside wbr
elements must not be considered part of the surrounding
text.
var wbr = document.createElement("wbr");wbr.textContent = "This is wrong"; document.body.appendChild(wbr);
This element has rendering requirements involving the bidirectional algorithm.
4.5.31. Usage summary
This section is non-normative.
Element | Purpose | Example |
---|---|---|
a
| Hyperlinks |
Visit my <a href="drinks.html">drinks</a> page. |
em
| Stress emphasis |
I must say I <em>adore</em> lemonade. |
strong
| Importance |
This tea is <strong>very hot</strong>. |
small
| Side comments |
These grapes are made into wine. <small>Alcohol is addictive.</small> |
s
| Inaccurate text |
Price: <s>£4.50</s> £2.00! |
cite
| Titles of works |
The case <cite>Hugo v. Danielle</cite> is relevant here. |
q
| Quotations |
The judge said <q>You can drink water from the fish tank</q> but advised against it. |
dfn
| Defining instance |
The term <dfn>organic food</dfn> refers to food produced without synthetic chemicals. |
abbr
| Abbreviations |
Organic food in Ireland is certified by the <abbr title="Irish Organic Farmers and Growers Association">IOFGA</abbr>. |
ruby , rb , rp , rt , rtc
| Ruby annotations |
<ruby> <rb>OJ <rp>(<rtc><rt>Orange Juice</rtc><rp>)</ruby> |
data
| Machine-readable equivalent |
Available starting today! <data value="UPC:022014640201">North Coast Organic Apple Cider</data> |
time
| Machine-readable equivalent of date- or time-related data |
Available starting on <time datetime="2011-11-18">November 18th</time>! |
code
| Computer code |
The <code>fruitdb</code> program can be used for tracking fruit production. |
var
| Variables |
If there are <var>n</var> fruit in the bowl, at least <var>n</var>÷2 will be ripe. |
samp
| Computer output |
The computer said <samp>Unknown error -3</samp>. |
kbd
| User input |
Hit <kbd>F1</kbd> to continue. |
sub
| Subscripts |
Water is H<sub>2</sub>O. |
sup
| Superscripts |
The Hydrogen in heavy water is usually <sup>2</sup>H. |
i
| Alternative voice |
Lemonade consists primarily of <i>Citrus limon</i>. |
b
| Keywords |
Take a <b>lemon</b> and squeeze it with a <b>juicer</b>. |
u
| Annotations |
The mixture of apple juice and <u class="spelling">eldeflower</u> juice is very pleasant. |
mark
| Highlight |
Elderflower cordial, with one <mark>part</mark> cordial to ten <mark>part</mark>s water, stands a<mark>part</mark> from the rest. |
bdi
| Text directionality isolation |
The recommended restaurant is <bdi lang="">My Juice Café (At The Beach)</bdi>. |
bdo
| Text directionality formatting |
The proposal is to write English, but in reverse order. "Juice" would become "<bdo dir=rtl>Juice</bdo>" |
span
| Other |
In French we call it <span lang="fr">sirop de sureau</span>. |
br
| Line break |
Simply Orange Juice Company<br>Apopka, FL 32703<br>U.S.A. |
wbr
| Line breaking opportunity |
www.simply<wbr>orange<wbr>juice.com |
4.6. Edits
The ins
and del
elements represent edits to the document.
4.6.1. The ins
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Transparent.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
cite
- Link to the source of the quotation or more information about the editdatetime
- Date and (optionally) time of the change - Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses the
HTMLModElement
interface.
The ins
element represents an addition to the document.
<aside> <ins> <p> I like fruit. </p> </ins> </aside>
As does the following, because everything in the aside
element here counts as phrasing content and therefore there is just one paragraph:
<aside> <ins> Apples are <em>tasty</em>. </ins> <ins> So are pears. </ins> </aside>
ins
elements should not cross implied paragraph boundaries.
ins
element in this example thus crosses a
paragraph boundary, which is considered poor form.
<aside> <!-- don’t do this --> <ins datetime="2005-03-16 00:00Z"> <p> I like fruit. </p> Apples are <em>tasty</em>. </ins> <ins datetime="2007-12-19 00:00Z"> So are pears. </ins> </aside>
Here is a better way of marking this up. It uses more elements, but none of the elements cross implied paragraph boundaries.
<aside> <ins datetime="2005-03-16 00:00Z"> <p> I like fruit. </p> </ins> <ins datetime="2005-03-16 00:00Z"> Apples are <em>tasty</em>. </ins> <ins datetime="2007-12-19 00:00Z"> So are pears. </ins> </aside>
4.6.2. The del
element
- Categories:
- Flow content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Transparent.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
cite
- Link to the source of the quotation or more information about the editdatetime
- Date and (optionally) time of the change - Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses the
HTMLModElement
interface.
The del
element represents a removal from the document.
del
elements should not cross implied paragraph boundaries.
<h1>To Do</h1> <ul> <li>Empty the dishwasher</li> <li><del datetime="2009-10-11T01:25-07:00">Watch Walter Lewin’s lectures</del></li> <li><del datetime="2009-10-10T23:38-07:00">Download more tracks</del></li> <li>Buy a printer</li> </ul>
4.6.3. Attributes common to ins
and del
elements
The cite
attribute may be used to specify the
address of a document that explains the change. When that document is long, for instance the
minutes of a meeting, authors are encouraged to include a fragment identifier pointing to the
specific part of that document that discusses the change.
If the cite
attribute is present, it must be a valid
URL potentially surrounded by spaces that explains the change. To obtain
the corresponding citation link, the value of the attribute must be resolved relative to the element. User agents may allow users to follow such
citation links, but they are primarily intended for private use (e.g., by server-side scripts
collecting statistics about a site’s edits), not for readers.
The datetime
attribute may be used to specify
the time and date of the change.
If present, the datetime
attribute’s value must be a valid date string with optional time.
User agents must parse the datetime
attribute according
to the parse a date or time string algorithm. If that doesn’t return a date or a global date and time,
then the modification has no associated timestamp (the value is non-conforming; it is not a valid date string with optional time). Otherwise, the modification is marked as
having been made at the given date or global date and time. If the given value is a global date and time then user agents should use the associated
time-zone offset information to determine which time zone to present the given datetime in.
This value may be shown to the user, but it is primarily intended for private use.
The ins
and del
elements must implement the HTMLModElement
interface:
interface HTMLModElement : HTMLElement { attribute DOMString cite; attribute DOMString dateTime; };
The cite
IDL attribute must reflect the element’s cite
content attribute. The dateTime
IDL attribute must reflect the
element’s datetime
content attribute.
4.6.4. Edits and paragraphs
This section is non-normative.
Since the ins
and del
elements do not affect paragraphing, it is possible, in some cases where paragraphs are implied (without explicit p
elements), for an ins
or del
element to span both an entire paragraph or other
non-phrasing content elements and part of another paragraph. For example:
<section> <ins> <p> This is a paragraph that was inserted. </p> This is another paragraph whose first sentence was inserted at the same time as the paragraph above. </ins> This is a second sentence, which was there all along. </section>
By only wrapping some paragraphs in p
elements, one can even get the end of one
paragraph, a whole second paragraph, and the start of a third paragraph to be covered by the same ins
or del
element (though this is very confusing, and not considered
good practice):
<section> This is the first paragraph. <ins>This sentence was inserted. <p>This second paragraph was inserted.</p> This sentence was inserted too.</ins> This is the third paragraph in this example. <!-- (don’t do this) --> </section>
However, due to the way implied paragraphs are defined, it is
not possible to mark up the end of one paragraph and the start of the very next one using the same ins
or del
element. You instead have to use one (or two) p
element(s) and two ins
or del
elements, as for example:
<section> <p>This is the first paragraph. <del>This sentence was deleted.</del></p> <p><del>This sentence was deleted too.</del> That sentence needed a separate <del> element.</p> </section>
Partly because of the confusion described above, authors are strongly encouraged to always mark
up all paragraphs with the p
element, instead of having ins
or del
elements that cross implied paragraphs boundaries.
4.6.5. Edits and lists
This section is non-normative.
The content models of the ol
and ul
elements do not allow ins
and del
elements as children. Lists always represent all their
items, including items that would otherwise have been marked as deleted.
To indicate that an item is inserted or deleted, an ins
or del
element can be wrapped around the contents of the li
element. To indicate that an
item has been replaced by another, a single li
element can have one or more del
elements followed by one or more ins
elements.
<h1>Stop-ship bugs</h1> <ol> <li><ins datetime="2008-02-12T15:20Z">Bug 225: Rain detector doesn’t work in snow</ins></li> <li><del datetime="2008-03-01T20:22Z"><ins datetime="2008-02-14T12:02Z">Bug 228: Water buffer overflows in April</ins></del></li> <li><ins datetime="2008-02-16T13:50Z">Bug 230: Water heater doesn’t use renewable fuels</ins></li> <li><del datetime="2008-02-20T21:15Z"><ins datetime="2008-02-16T14:25Z">Bug 232: Carbon dioxide emissions detected after startup</ins></del></li> </ol>
<h1>List of <del>fruits</del><ins>colors</ins></h1> <ul> <li><del>Lime</del><ins>Green</ins></li> <li><del>Apple</del></li> <li>Orange</li> <li><del>Pear</del></li> <li><ins>Teal</ins></li> <li><del>Lemon</del><ins>Yellow</ins></li> <li>Olive</li> <li><ins>Purple</ins></li> </ul>
4.6.6. Edits and tables
This section is non-normative.
The elements that form part of the table model have complicated content model requirements that
do not allow for the ins
and del
elements, so indicating edits to a
table can be difficult.
To indicate that an entire row or an entire column has been added or removed, the entire
contents of each cell in that row or column can be wrapped in ins
or del
elements (respectively).
<table> <thead> <tr> <th> Game name <th> Game publisher <th> Verdict <tbody> <tr> <td> Diablo 2 <td> Blizzard <td> 8/10 <tr> <td> Portal <td> Valve <td> 10/10 <tr> <td> <ins>Portal 2</ins> <td> <ins>Valve</ins> <td> <ins>10/10</ins> </table>
Here, a column has been removed (the time at which it was removed is given also, as is a link to the page explaining why):
<table> <thead> <tr> <th> Game name <th> Game publisher <th> <del cite="/edits/r192" datetime="2011-05-02 14:23Z">Verdict</del> <tbody> <tr> <td> Diablo 2 <td> Blizzard <td> <del cite="/edits/r192" datetime="2011-05-02 14:23Z">8/10</del> <tr> <td> Portal <td> Valve <td> <del cite="/edits/r192" datetime="2011-05-02 14:23Z">10/10</del> <tr> <td> Portal 2 <td> Valve <td> <del cite="/edits/r192" datetime="2011-05-02 14:23Z">10/10</del> </table>
Generally speaking, there is no good way to indicate more complicated edits (e.g., that a cell was removed, moving all subsequent cells up or to the left).
4.7. Embedded content
4.7.1. Introduction
This section is non-normative.
To embed an image in HTML, when there is only a single image resource,
use the img
element and with its src
and alt
attributes.
<h2>From today’s featured article</h2> <img src="/uploads/100-marie-lloyd.jpg" alt="" width="100" height="150"> <p><b><a href="/wiki/Marie_Lloyd">Marie Lloyd</a></b> (1870–1922) was an English <a href="/wiki/Music_hall">music hall</a> singer, ...
However, there are a number of situations for which the author might wish to use multiple image resources that the user agent can choose from:
-
Different users might have different environmental characteristics:
-
The users' physical screen size might be different from one another.
A mobile phone’s screen might be 4 inches diagonally, while a laptop’s screen might be 14 inches diagonally.This is only relevant when an image’s rendered size depends on the viewport size.
-
The users' screen pixel density might be different from one another.
-
The users' zoom level might be different from one another, or might change for a single user over time.
A user might zoom in to a particular image to be able to get a more detailed look.
The zoom level and the screen pixel density (the previous point) can both affect the number of physical screen pixels per CSS pixel. This ratio is usually referred to as device-pixel-ratio.
-
The users' screen orientation might be different from one another, or might change for a single user over time.
-
The users' network speed, network latency and bandwidth cost might be different from one another, or might change for a single user over time.
A user might be on a fast, low-latency and constant-cost connection while at work, on a slow, low-latency and constant-cost connection while at home, and on a variable-speed, high-latency and variable-cost connection anywhere else.
-
-
Authors might want to show the same image content but with different rendered size depending on, usually, the width of the viewport. This is usually referred to as viewport-based selection.
A Web page might have a banner at the top that always spans the entire viewport width. In this case, the rendered size of the image depends on the physical size of the screen (assuming a maximised browser window).Another Web page might have images in columns, with a single column for screens with a small physical size, two columns for screens with medium physical size, and three columns for screens with big physical size, with the images varying in rendered size in each case to fill up the viewport. In this case, the rendered size of an image might be bigger in the one-column layout compared to the two-column layout, despite the screen being smaller. -
Authors might want to show different image content depending on the rendered size of the image. This is usually referred to as art direction.
When a Web page is viewed on a screen with a large physical size (assuming a maximised browser window), the author might wish to include some less relevant parts surrounding the critical part of the image. When the same Web page is viewed on a screen with a small physical size, the author might wish to show only the critical part of the image. -
Authors might want to show the same image content but using different image formats, depending on which image formats the user agent supports. This is usually referred to as image format-based selection.
A Web page might have some images in the JPEG, WebP and JPEG XR image formats, with the latter two having better compression abilities compared to JPEG. Since different user agents can support different image formats, with some formats offering better compression ratios, the author would like to serve the better formats to user agents that support them, while providing JPEG fallback for user agents that don’t.
The above situations are not mutually exclusive. For example, it is reasonable to combine different resources for different device-pixel-ratio with different resources for art direction.
While it is possible to solve these problems using scripting, doing so introduces some other problems:
- Some user agents aggressively download images specified in the HTML markup, before scripts have had a chance to run, so that Web pages complete loading sooner. If a script changes which image to download, the user agent will potentially start two separate downloads, which can instead cause worse page loading performance.
- If the author avoids specifying any image in the HTML markup and instead instantiates a single download from script, that avoids the double download problem above but instead it makes no image be downloaded at all for users with scripting disabled and it disables the agressive image downloading optimization.
With this in mind, this specification introduces a number of features to address the above problems in a declarative manner.
- Device-pixel-ratio-based selection when the rendered size of the image is fixed
-
The
src
andsrcset
attributes on theimg
element can be used, using thex
descriptor, to provide multiple images that only vary in their size (the smaller image is a scaled-down version of the bigger image).The
x
descriptor is not appropriate when the rendered size of the image depends on the viewport width (viewport-based selection), but can be used together with art direction.<h2>From today’s featured article</h2> <img src="/uploads/100-marie-lloyd.jpg" srcset="/uploads/150-marie-lloyd.jpg 1.5x, /uploads/200-marie-lloyd.jpg 2x" alt="" width="100" height="150"> <p><b><a href="/wiki/Marie_Lloyd">Marie Lloyd</a></b> (1870–1922) was an English <a href="/wiki/Music_hall">music hall</a> singer, ...
The user agent can choose any of the given resources depending on the user’s screen’s pixel density, zoom level, and possibly other factors such as the user’s network conditions.
For backwards compatibility with older user agents that don’t yet understand the
srcset
attribute, one of the URLs is specified in theimg
element’ssrc
attribute. This will result in something useful (though perhaps lower-resolution than the user would like) being displayed even in older user agents. For new user agents, thesrc
attribute participates in the resource selection, as if it was specified insrcset
with a1x
descriptor.The image’s rendered size is given in the
width
andheight
attributes, which allows the user agent to allocate space for the image before it is downloaded. - Viewport-based selection
-
The
srcset
andsizes
attributes can be used, using thew
descriptor, to provide multiple images that only vary in their size (the smaller image is a scaled-down version of the bigger image).In this example, a banner image takes up the entire viewport width (using appropriate CSS).<h1><img sizes="100vw" srcset="wolf-400.jpg 400w, wolf-800.jpg 800w, wolf-1600.jpg 1600w" src="wolf-400.jpg" alt="The rad wolf"></h1>
The user agent will calculate the effective pixel density of each image from the specified
w
descriptors and the specified rendered size in thesizes
attribute. It can then choose any of the given resources depending on the user’s screen’s pixel density, zoom level, and possibly other factors such as the user’s network conditions.If the user’s screen is 320 CSS pixels wide, this is equivalent to specifying
wolf-400.jpg 1.25x, wolf-800.jpg 2.5x, wolf-1600.jpg 5x
. On the other hand, if the user’s screen is 1200 CSS pixels wide, this is equivalent to specifyingwolf-400.jpg 0.33x, wolf-800.jpg 0.67x, wolf-1600.jpg 1.33x
. By using thew
descriptors and thesizes
attribute, the user agent can choose the correct image source to download regardless of how large the user’s device is.For backwards compatibility, one of the URLs is specified in the
img
element’ssrc
attribute. In new user agents, thesrc
attribute is ignored when thesrcset
attribute usesw
descriptors.In this example, the
sizes
attribute could be omitted because the default value is100vw
.In this example, the Web page has three layouts depending on the width of the viewport. The narrow layout has one column of images (the width of each image is about 100%), the middle layout has two columns of images (the width of each image is about 50%), and the widest layout has three columns of images, and some page margin (the width of each image is about 33%). It breaks between these layouts when the viewport is30em
wide and50em
wide, respectively.<img sizes="(max-width: 30em) 100vw, (max-width: 50em) 50vw, calc(33vw - 100px)" srcset="swing-200.jpg 200w, swing-400.jpg 400w, swing-800.jpg 800w, swing-1600.jpg 1600w" src="swing-400.jpg" alt="Kettlebell Swing">
The
sizes
attribute sets up the layout breakpoints at30em
and50em
, and declares the image sizes between these breakpoints to be100vw
,50vw
, orcalc(33vw - 100px)
. These sizes do not necessarily have to match up exactly with the actual image width as specified in the CSS.The user agent will pick a width from the
sizes
attribute, using the first item with a <media-condition> (the part in parentheses) that evaluates to true, or using the last item (calc(33vw - 100px)
) if they all evaluate to false.For example, if the viewport width is
29em
, then(max-width: 30em)
evaluates to true and100vw
is used, so the image size, for the purpose of resource selection, is29em
. If the viewport width is instead32em
, then(max-width: 30em)
evaluates to false, but(max-width: 50em)
evaluates to true and50vw
is used, so the image size, for the purpose of resource selection, is16em
(half the viewport width). Notice that the slightly wider viewport results in a smaller image because of the different layout.The user agent can then calculate the effective pixel density and choose an appropriate resource similarly to the previous example.
- Art direction-based selection
-
The
picture
element and thesource
element, together with themedia
attribute, can be used, to provide multiple images that vary the image content (for intance the smaller image might be a cropped version of the bigger image).<picture> <source media="(min-width: 45em)" srcset="large.jpg"> <source media="(min-width: 32em)" srcset="med.jpg"> <img src="small.jpg" alt="The wolf runs through the snow."> </picture>
The user agent will choose the first
source
element for which the media query in themedia
attribute matches, and then choose an appropriate URL from itssrcset
attribute.The rendered size of the image varies depending on which resource is chosen. To specify dimensions that the user agent can use before having downloaded the image, CSS can be used.
img { width: 300px; height: 300px } @media (min-width: 32em) { img { width: 500px; height:300px } } @media (min-width: 45em) { img { width: 700px; height:400px } }
This example combines art direction- and device-pixel-ratio-based selection. A banner that takes half the viewport is provided in two versions, one for wide screens and one for narrow screens.<h1> <picture> <source media="(max-width: 500px)" srcset="banner-phone.jpeg, banner-phone-HD.jpeg 2x"> <img src="banner.jpeg" srcset="banner-HD.jpeg 2x" alt="The Breakfast Combo"> </picture> </h1>
- Image format-based selection
-
The
type
attribute on thesource
element can be used, to provide multiple images in different formats.<h2>From today’s featured article</h2> <picture> <source srcset="/uploads/100-marie-lloyd.webp" type="image/webp"> <source srcset="/uploads/100-marie-lloyd.jxr" type="image/vnd.ms-photo"> <img src="/uploads/100-marie-lloyd.jpg" alt="" width="100" height="150"> </picture> <p><b><a href="/wiki/Marie_Lloyd">Marie Lloyd</a></b> (1870–1922) was an English <a href="/wiki/Music_hall">music hall</a> singer, ...
In this example, the user agent will choose the first
source
that has atype
attribute with a supported MIME type. If the user agent supports WebP images, the firstsource
element will be chosen. If not, but the user agent does support JPEG XR images, the secondsource
element will be chosen. If neither of those formats are supported, theimg
element will be chosen.
4.7.2. Dependencies
-
Media Queries [MEDIAQ]
-
CSS Values and Units [CSS-VALUES]
-
CSS Syntax [CSS-SYNTAX-3]
-
Parse a comma-separated list of component values
4.7.3. The picture
element
- Categories:
- Flow content.
- Phrasing content.
- Embedded content.
- Phrasing content.
- Contexts in which this element can be used:
- Where embedded content is expected.
- Content model:
- Zero or more
source
elements, followed by oneimg
element, optionally intermixed with script-supporting elements. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLPictureElement : HTMLElement {};
The picture
element is a container
which provides multiples sources to its contained img
element
to allow authors to declaratively control or give hints to the user agent about which image resource to use,
based on the screen pixel density, viewport size, image format, and other factors. It represents its children.
The picture
element is somewhat different
from the similar-looking video
and audio
elements.
While all of them contain source
elements,
the source
element’s src
attribute has no meaning
when the element is nested within a picture
element,
and the resource selection algorithm is different.
As well, the picture
element itself does not display anything;
it merely provides a context for its contained img
element
that enables it to choose from multiple URLs.
4.7.4. The source
element when used with the picture
element
- Categories:
- Same as for the
source
element. - Contexts in which this element can be used:
- As a child of a
picture
element, before theimg
element. - Content model:
- Same as for the
source
element. - Tag omission in text/html:
- No end tag
- Content attributes:
- Global attributes
srcset
- Images to use in different situations (e.g., high-resolution displays, small monitors, etc)sizes
- Image sizes between breakpointsmedia
- Applicable mediatype
- Type of embedded resource - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
partial interface HTMLSourceElement { attribute DOMString srcset; attribute DOMString sizes; attribute DOMString media; };
The authoring requirements in this section only apply if the source
element has
a parent that is a picture
element.
The source
element allows authors to specify multiple alternative source sets for img
elements.
It does not represent anything on its own.
The srcset
content attribute must be present,
and must consist of one or more image candidate strings,
each separated from the next by a U+002C COMMA character (,).
If an image candidate string contains no descriptors
and no space characters after the URL,
the following image candidate string, if there is one,
must begin with one or more space characters.
If the srcset
attribute has any image candidate strings using a width descriptor,
the sizes
content attribute must also be present,
and the value must be a valid source size list.
The media
content attribute may also be present.
If present, the value must contain a valid media query list.
The type
content attribute may also be present.
If present, the value must be a valid mime type.
It gives the type of the images in the source set,
to allow the user agent to skip to the next source
element
if it does not support the given type.
If the type
attribute
is not specified, the user agent will not select a different source
element if it finds that it does not support
the image format after fetching it.
When a source
element has a following sibling source
element or img
element with a srcset
attribute specified, it must have
at least one of the following:
- A
media
attribute specified with a value that, after stripping leading and trailing whitespace, is not the empty string and is not an ASCII case-insensitive match for the string "all
". - A
type
attribute specified.
The src
attribute must not be present.
The IDL attributes srcset
, sizes
and media
must reflect the
respective content attributes of the same name.
4.7.5. The img
element
- Categories:
- Flow content.
- Phrasing content.
- Embedded content.
- Form-associated element.
- If the element has a
usemap
attribute: interactive content.- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where embedded content is expected.
- Content model:
- Nothing
- Tag omission in text/html:
- No end tag.
- Content attributes:
- Global attributes
alt
- Replacement text for use when images are not availablesrc
- Address of the resourcesrcset
- Images to use in different situations (e.g., high-resolution displays, small monitors, etc)sizes
- Image sizes between breakpointscrossorigin
- How the element handles crossorigin requestsusemap
- Name of image map to useismap
- Whether the image is a server-side image mapwidth
- Horizontal dimensionheight
- Vertical dimension - Allowed ARIA role attribute values:
presentation
role only, for animg
element whosealt
attribute’s value is empty (alt=""
), otherwise Any role value.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
[NamedConstructor=Image(optional unsigned long width, optional unsigned long height)] interface HTMLImageElement : HTMLElement { attribute DOMString alt; attribute DOMString src; attribute DOMString srcset; attribute DOMString sizes; attribute DOMString? crossOrigin; attribute DOMString useMap; attribute boolean isMap; attribute unsigned long width; attribute unsigned long height; readonly attribute unsigned long naturalWidth; readonly attribute unsigned long naturalHeight; readonly attribute boolean complete; readonly attribute DOMString currentSrc; };
An img
element represents an image and its fallback content.
The image given by the src
and srcset
attributes,
and any previous sibling source
elements' srcset
attributes if the parent is a picture
element,
is the embedded content; the value of
the alt
attribute is the img
element’s fallback content, and provides equivalent content for
users and user agents who cannot process images or have image loading disabled.
Requirements for alternative representations of the image are described in the next section.
The src
attribute must be present, and must contain a valid non-empty URL potentially surrounded by spaces referencing a non-interactive,
optionally animated, image resource that is neither paged nor scripted.
The srcset
attribute may also be present.
If present, its value must consist of one or more image candidate strings,
each separated from the next by a U+002C COMMA character (,).
If an image candidate string contains no descriptors
and no space characters after the URL,
the following image candidate string, if there is one,
must begin with one or more space characters.
An image candidate string consists of the following components, in order, with the further restrictions described below this list:
- Zero or more space characters.
- A valid non-empty URL that does not start or end with a U+002C COMMA character (,), referencing a non-interactive, optionally animated, image resource that is neither paged nor scripted.
- Zero or more space characters.
-
Zero or one of the following:
- A width descriptor, consisting of: a space character, a valid non-negative integer giving a number greater than zero representing the width descriptor value, and a U+0077 LATIN SMALL LETTER W character.
- A pixel density descriptor, consisting of: a space character, a valid floating-point number giving a number greater than zero representing the pixel density descriptor value, and a U+0078 LATIN SMALL LETTER X character.
- Zero or more space characters.
There must not be an image candidate string for an element that has the same width descriptor value as another image candidate string’s width descriptor value for the same element.
There must not be an image candidate string for an element that
has the same pixel density descriptor value as another image candidate string’s pixel density descriptor value for the same element.
For the purpose of this requirement,
an image candidate string with no descriptors is equivalent to
an image candidate string with a 1x
descriptor.
If a source
element has a sizes
attribute present
or an img
element has a sizes
attribute present,
all image candidate strings for that
element must have the width descriptor specified.
If an image candidate string for a source
or img
element has the width descriptor specified, all other image candidate strings for that element must also
have the width descriptor specified.
The specified width in an image candidate string’s width descriptor must match the intrinsic width in the resource given by the image candidate string’s URL, if it has an intrinsic width.
The requirements above imply that images can be static bitmaps (e.g., PNGs, GIFs, JPEGs), single-page vector documents (single-page PDFs, XML files with an SVG root element), animated bitmaps (APNGs, animated GIFs), animated vector graphics (XML files with an SVG root element that use declarative SMIL animation), and so forth. However, these definitions preclude SVG files with script, multipage PDF files, interactive MNG files, HTML documents, plain text documents, and so forth. [PNG] [GIF] [JPEG] [PDF] [XML] [APNG] [SVG11] [MNG]
If the srcset
attribute is present,
the sizes
attribute may also be present.
If present, its value must be a valid source size list.
A valid source size list is a string that matches the following grammar: [CSS-VALUES] [MEDIAQ]
<source-size-list> = <source-size># [ , <source-size-value> ]? | <source-size-value> <source-size> = <media-condition> <source-size-value> <source-size-value> = <length>
A <source-size-value>
must not be negative.
Percentages are not allowed in a <source-size-value>
,
to avoid confusion about what it would be relative to.
The vw
unit can be used for sizes relative to the viewport width.
The img
element must not be used as a layout tool. In particular, img
elements should not be used to display transparent images, as such images rarely convey meaning and
rarely add anything useful to the document.
The crossorigin
attribute is a CORS
settings attribute. Its purpose is to allow images from third-party sites that allow
cross-origin access to be used with canvas
.
An img
element has a current request and a pending request.
The current request is initially set to a new image request.
The pending request is initially set to null.
The current request is usually referred to as the img
element itself.
An image request has a state, current URL and image data.
An image request’s state is one of the following:
- Unavailable
- The user agent hasn’t obtained any image data, or has obtained some or all of the image data but hasn’t yet decoded enough of the image to get the image dimensions.
- Partially available
- The user agent has obtained some of the image data and at least the image dimensions are available.
- Completely available
- The user agent has obtained all of the image data and at least the image dimensions are available.
- Broken
- The user agent has obtained all of the image data that it can, but it cannot even decode the image enough to get the image dimensions (e.g., the image is corrupted, or the format is not supported, or no data could be obtained).
An image request’s current URL is initially the empty string.
An image request’s image data is the decoded image data.
When an image request is either in the partially available state or in the completely available state, it is said to be available.
An image request is initially unavailable.
When an img
element is available,
it provides a paint source whose width is the image’s density-corrected intrinsic width (if any),
whose height is the image’s density-corrected intrinsic height (if any),
and whose appearance is the intrinsic appearance of the image.
In a browsing context where scripting is disabled, user agents may obtain images immediately or on demand. In a browsing context where scripting is enabled, user agents must obtain images immediately.
A user agent that obtains images immediately must immediately update the image data of an img
element,
with the restart animation flag set if so stated,
whenever that element is created or has experienced relevant mutations.
A user agent that obtains images on demand must update the image data of an img
element whenever it needs the image data (i.e., on demand),
but only if the img
element is in the unavailable state. When an img
element
has experienced relevant mutations, if the user
agent only obtains images on demand, the img
element must return to the unavailable state.
The relevant mutations for an img
element are as follows:
- The element’s
src
,srcset
,width
, orsizes
attributes are set, changed, or removed. - The element’s
src
attribute is set to the same value as the previous value. This must set the restart animation flag for the update the image data algorithm. - The element’s
crossorigin
attribute’s state is changed. - The element is inserted into or removed from a
picture
parent element. - The element’s parent is a
picture
element and asource
element is inserted as a previous sibling. - The element’s parent is a
picture
element and asource
element that was a previous sibling is removed. - The element’s parent is a
picture
element and asource
element that is a previous sibling has itssrcset
,sizes
,media
ortype
attributes set, changed, or removed. - The element’s adopting steps are run.
Each img
element has a last selected source, which must initially be
null.
Each image request has a current pixel density, which must initially be undefined.
When an img
element has a current pixel density that is not 1.0, the
element’s image data must be treated as if its resolution, in device pixels per CSS pixels, was
the current pixel density.
The image’s density-corrected intrinsic width and height are the intrinsic width and height after taking into account the current pixel density.
For example, given a screen with 96 CSS pixels per CSS inch, if the current pixel density is 3.125, that means that there are 96 × 3.125 = 300 device pixels per CSS inch, and thus if the image data is 300x600, it has intrinsic dimensions of 300 ÷ 3.125 = 96 CSS pixels by 600 ÷ 3.125 = 192 CSS pixels. With a current pixel density of 2.0 (192 device pixels per CSS inch) and the same image data (300x600), the intrinsic dimensions would be 150x300.
Each Document
object must have a list of available images. Each image
in this list is identified by a tuple consisting of an absolute URL, a CORS
settings attribute mode, and, if the mode is not No CORS, an origin.
Each image furthermore has an ignore higher-layer caching flag.
User agents may copy entries from one Document
object’s list of available images to another at any time (e.g., when the Document
is created, user agents can add to it all the images that are loaded in
other Document
s), but must not change the keys of entries copied in this way when
doing so, and must unset the ignore higher-layer caching flag for the copied entry.
User agents may also remove images from such lists at any time (e.g., to save
memory).
User agents must remove entries in the list of available images as appropriate
given higher-layer caching semantics for the resource (e.g., the HTTP Cache-Control
response header) when the ignore higher-layer caching flag is unset.
The list of available images is intended to enable synchronous
switching when changing the src
attribute to a URL that has
previously been loaded, and to avoid re-downloading images in the same document even when they
don’t allow caching per HTTP. It is not used to avoid re-downloading the same image while the
previous image is still loading.
For example, if a resource has the HTTP response header Cache-Control: must-revalidate
,
the user agent would remove it from the list of available images but could keep the image data separately,
and use that if the server responds with a 204 No Content
status.
When the user agent is to update the image data of an img
element,
optionally with the restart animations flag set,
it must run the following steps:
-
If the element’s node document is not the active document, then run these substeps:
- Continue running this algorithm in parallel.
- Wait until the element’s node document is the active document.
- If another instance of this algorithm for this
img
element was started after this instance (even if it aborted and is no longer running), then abort these steps. - Queue a microtask to continue this algorithm.
- If the user agent cannot support images, or its support for images has been disabled, then abort the image request for the current request and the pending request, set current request to the unavailable state, let pending request be null, and abort these steps.
-
If the element does not use
srcset
orpicture
and it does not have a parent or it has a parent but it is not apicture
element, and it has asrc
attribute specified and its value is not the empty string, let selected source be the value of the element’ssrc
attribute, and selected pixel density be 1.0. Otherwise, let selected source be null and selected pixel density be undefined. - Let the
img
element’s last selected source be selected source. -
If selected source is not null, run these substeps:
- Parse selected source, relative to the element, and let the result be absolute URL. If that is not successful, then abort these inner set of steps.
- Let key be a tuple consisting of the resulting absolute URL, the
img
element’scrossorigin
attribute’s mode, and, if that mode is not No CORS, the node document’s origin. -
If the list of available images contains an entry for key, run these subsubsteps:
- Set the ignore higher-layer caching flag for that entry.
- Abort the image request for the current request and the pending request.
- Let pending request be null.
- Let current request be a new image request whose image data is that of the entry and whose state is set to the completely available state.
- Update the presentation of the image appropriately.
- Let the current request’s current pixel density be selected pixel density.
- Queue a task to restart the animation if restart
animation is set, change current request’s current URL to absolute URL, and then fire a simple event named
load
at theimg
element. - Abort the update the image data algorithm.
- in parallel await a stable state, allowing the task that invoked this algorithm to continue. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)
-
⌛ If another instance of this algorithm for this
img
element was started after this instance (even if it aborted and is no longer running), then abort these steps.Only the last instance takes effect, to avoid multiple requests when, for example, the
src
,srcset
, andcrossorigin
attributes are all set in succession. -
⌛ Let selected source and selected pixel density be the URL and pixel density that results from selecting an image source, respectively.
-
⌛ If selected source is null, run these substeps:
- ⌛ Set the current request to the broken state, abort the image request for the current request and the pending request, and let pending request be null.
- ⌛ Queue a task to change the current request’s current URL to
the empty string, and then, if the element has a
src
attribute or it usessrcset
orpicture
<, fire a simple event namederror
at theimg
element. - ⌛ Abort this algorithm.
-
⌛ Queue a task to fire a progress event named
loadstart
at theimg
element.⌛ Parse selected source, relative to the element’s node document, and let absolute URL be the resulting URL string. If that is not successful, run these substeps:
- ⌛ Abort the image request for the current request and the pending request.
- ⌛ Set the current request to the broken state.
- ⌛ Let pending request be null.
- ⌛ Queue a task to change the current request’s current URL to selected source, fire a simple event named
error
at theimg
element and then fire a simple event namedloadend
at theimg
element. - ⌛ Abort the update the image data algorithm.
-
⌛ If the pending request is not null, and absolute URL is the same as the pending request’s current URL, then abort these steps.
⌛ If absolute URL is the same as the current request’s current URL, and current request is in the partially available state, then abort the image request for the pending request, queue a task to restart the animation if restart animation is set, and abort these steps.
⌛ If the pending request is not null, abort the image request for the pending request.
⌛ Let image request be a new image request whose current URL is absolute URL.
⌛ If current request is in the unavailable state or the broken state, let the current request be image request. Otherwise, let the pending request be image request.
⌛ Let request be the result of creating a potential-CORS request given absolute URL and the current state of the element’s
crossorigin
content attribute.⌛ Set request’s client to the element’s node document’s
Window
object’s environment settings object and type to "image
".⌛ If the element uses
srcset
orpicture
, set request’s initiator to "imageset
".⌛ Set request’s same-origin data-URL flag.
⌛ Fetch request. Let this instance of the fetching algorithm be associated with image request.
The resource obtained in this fashion, if any, is image request’s image data. It can be either CORS-same-origin or CORS-cross-origin; this affects the origin of the image itself (e.g., when used on a
canvas
).Fetching the image must delay the load event of the element’s node document until the task that is queued by the networking task source once the resource has been fetched (defined below) has been run.
This, unfortunately, can be used to perform a rudimentary port scan of the user’s local network (especially in conjunction with scripting, though scripting isn’t actually necessary to carry out such an attack). User agents may implement cross-origin access control policies that are stricter than those described above to mitigate this attack, but unfortunately such policies are typically not compatible with existing Web content.
If the resource is CORS-same-origin, each task that is queued by the networking task source while the image is being fetched, if image request is the current request, must fire a progress event named
progress
at theimg
element. - End the synchronous section, continuing the remaining steps in parallel, but without missing any data from fetching.
-
As soon as possible, jump to the first applicable entry from the following list:
- If the resource type is
multipart/x-mixed-replace
-
The next task that is queued by the networking task source while the image is being fetched must run the following steps:
-
If image request is the pending request and at least one body part has been completely decoded, abort the image request for the current request, upgrade the pending request to the current request.
-
Otherwise, if image request is the pending request and the user agent is able to determine that image request’s image is corrupted in some fatal way such that the image dimensions cannot be obtained, abort the image request for the current request, upgrade the pending request to the current request and set the current request’s state to broken.
-
Otherwise, if image request is the current request, it is in the unavailable state, and the user agent is able to determine image request’s image’s width and height, set the current request’s state to partially available.
-
Otherwise, if image request is the current request, it is in the unavailable state, and the user agent is able to determine that image request’s image is corrupted in some fatal way such that the image dimensions cannot be obtained, set the current request’s state to broken.
Each task that is queued by the networking task source while the image is being fetched must update the presentation of the image, but as each new body part comes in, it must replace the previous image. Once one body part has been completely decoded, the user agent must set the
img
element to the completely available state and queue a task to fire a simple event namedload
at theimg
element.The
progress
andloadend
events are not fired formultipart/x-mixed-replace
image streams. -
- If the resource type and data corresponds to a supported image format, as described below
-
The next task that is queued by the networking task source while the image is being fetched must run the following steps:
-
If the user agent is able to determine image request’s image’s width and height, and image request is pending request, set image request’s state to partially available.
-
Otherwise, if the user agent is able to determine image request’s image’s width and height, and image request is current request, update the
img
element’s presentation appropriately and set image request’s state to partially available. -
Otherwise, if the user agent is able to determine that image request’s image is corrupted in some fatal way such that the image dimensions cannot be obtained, and image request is pending request, abort the image request for the current request and the pending request, upgrade the pending request to the current request, set current request to the broken state, fire a simple event named
error
at theimg
element, fire a simple event namedloadend
at theimg
element, and abort these steps. -
Otherwise, if the user agent is able to determine that image request’s image is corrupted in some fatal way such that the image dimensions cannot be obtained, and image request is current request, abort the image request for image request, fire a simple event named
error
at theimg
element, fire a simple event namedloadend
at theimg
element, and abort these steps.
That task, and each subsequent task, that is queued by the networking task source while the image is being fetched, if image request is the current request, must update the presentation of the image appropriately (e.g., if the image is a progressive JPEG, each packet can improve the resolution of the image).
Furthermore, the last task that is queued by the networking task source once the resource has been fetched must additionally run these steps:
- If image request is the pending request, abort the image request for the current request, upgrade the pending request to the current request and
update the
img
element’s presentation appropriately. - Set image request to the completely available state.
- Add the image to the list of available images using the key key, with the ignore higher-layer caching flag set.
- Fire a progress event or simple event named
load
at theimg
element, depending on the resource in image request. - Fire a progress event or simple event named
loadend
at theimg
element, depending on the resource in image request.
-
- Otherwise
-
The image data is not in a supported file format; the user agent must set image request to the broken state, abort the image request for the current request and the pending request, upgrade the pending request to the current request if image request is the pending request, and then queue a task to first fire a simple event named
error
at theimg
element and then fire a simple event namedloadend
at theimg
element.
- If the resource type is
To abort the image request for an image request image request means to run the following steps:
- Forget image request’s image data, if any.
- Abort any instance of the fetching algorithm for image request, discarding any pending tasks generated by that algorithm.
To upgrade the pending request to the current request for an img
element means to run the following steps:
- Let the
img
element’s current request be the pending request. - Let the
img
element’s pending request be null.
To fire a progress event or simple event named type at an element e, depending on resource r, means to fire a progress event named type at e if r is CORS-same-origin, and otherwise fire a simple event named type at e.
While a user agent is running the above algorithm for an element x, there
must be a strong reference from the element’s node document to the element x,
even if that element is not in its Document
.
An img
element is said to use srcset
or picture
if it has a srcset
attribute specified or if it has a parent that is a picture
element.
When an img
element is in the completely available state and the user agent can decode the media data without errors, then the img
element is said to be fully decodable.
Whether the image is fetched successfully or not (e.g., whether the response status was an ok status) must be ignored when determining the image’s type and whether it is a valid image.
This allows servers to return images with error responses, and have them displayed.
The user agent should apply the image sniffing rules to determine the type of the image, with the image’s associated Content-Type headers giving the official type. If these rules are not applied, then the type of the image must be the type given by the image’s associated Content-Type headers.
User agents must not support non-image resources with the img
element (e.g., XML
files whose root element is an HTML element). User agents must not run executable code (e.g.,
scripts) embedded in the image resource. User agents must only display the first page of a
multipage resource (e.g., a PDF file). User agents must not allow the resource to act in an
interactive fashion, but should honor any animation in the resource.
This specification does not specify which image types are to be supported.
An img
element is associated with a source set.
A source set is an ordered set of zero or more image sources and a source size.
An image source is a URL, and optionally either a density descriptor, or a width descriptor.
A source size is a <source-size-value>
.
When a source size has a unit relative to the viewport,
it must be interpreted relative to the img
element’s document’s viewport.
Other units must be interpreted the same as in Media Queries. [MEDIAQ]
When asked to select an image source for a given img
element el, user agents must do the following:
- Update the source set for el.
- If el’s source set is empty, return null as the URL and undefined as the pixel density and abort these steps.
- Otherwise, take el’s source set and let it be source set.
- If an entry b in source set has the same associated density descriptor as an earlier entry a in source set, then remove entry b. Repeat this step until none of the entries in source set have the same associated density descriptor as an earlier entry.
- In a user agent-specific manner, choose one image source from source set. Let this be selected source.
- Return selected source and its associated pixel density.
When asked to update the source set for a given img
element el,
user agents must do the following:
- Set el’s source set to an empty source set.
- If el has a parent node and that is a
picture
element, let elements be an array containing el’s parent node’s child elements, retaining relative order. Otherwise, let elements be array containing only el. - If el has a
width
attribute, and parsing that attribute’s value using the rules for parsing dimension values doesn’t generate an error or a percentage value, then let width be the returned integer value. Otherwise, let width be null. -
Iterate through elements, doing the following for each item child:
-
If child is el:
- If child has a
srcset
attribute, parse child’s srcset attribute and let the returned source set be source set. Otherwise, let source set be an empty source set. - Parse child’s sizes attribute with the fallback width width, and let source set’s source size be the returned value.
- If child has a
src
attribute whose value is not the empty string and source set does not contain an image source with a density descriptor value of 1, and no image source with a width descriptor, append child’ssrc
attribute value to source set. - Normalize the source densities of source set.
- Let el’s source set be source set.
- Abort this algorithm.
- If child has a
- If child is not a
source
element, continue to the next child. Otherwise, child is asource
element. - If child does not have a
srcset
attribute, continue to the next child. - Parse child’s
srcset
attribute and let the returned source set be source set. - If source set has zero image sources, continue to the next child.
- If child has a
media
attribute, and its value does not match the environment, continue to the next child. - Parse child’s
sizes
attribute with the fallback width width, and let source set’s source size be the returned value. - If child has a
type
attribute, and its value is an unknown or unsupported MIME type, continue to the next child. - Normalize the source densities of source set.
- Let el’s source set be source set.
- Abort this algorithm.
-
Each img
element independently considers
its previous sibling source
elements
plus the img
element itself
for selecting an image source, ignoring any other (invalid) elements,
including other img
elements in the same picture
element,
or source
elements that are following siblings
of the relevant img
element.
When asked to parse a srcset attribute from an element,
parse the value of the element’s srcset
attribute as follows:
- Let input be the value passed to this algorithm.
- Let position be a pointer into input, initially pointing at the start of the string.
- Let candidates be an initially empty source set.
- Splitting loop: Collect a sequence of characters that are space characters or U+002C COMMA characters. If any U+002C COMMA characters were collected, that is a parse error.
- If position is past the end of input, return candidates and abort these steps.
- Collect a sequence of characters that are not space characters, and let that be url.
- Let descriptors be a new empty list.
-
If url ends with a U+002C COMMA character (,), follow these substeps:
- Remove all trailing U+002C COMMA characters from url. If this removed more than one character, that is a parse error.
Otherwise, follow these substeps:
- Descriptor tokenizer: Skip whitespace
- Let current descriptor be the empty string.
- Let state be in descriptor.
-
Let c be the character at position. Do the following depending on the value of state. For the purpose of this step, "EOF" is a special character representing that position is past the end of input.
- In descriptor
-
Do the following, depending on the value of c:
- Space character
- If current descriptor is not empty, append current descriptor to descriptors and let current descriptor be the empty string. Set state to after descriptor.
- U+002C COMMA (,)
- Advance position to the next character in input. If current descriptor is not empty, append current descriptor to descriptors. Jump to the step labeled descriptor parser.
- U+0028 LEFT PARENTHESIS (()
- Append c to current descriptor. Set state to in parens.
- EOF
- If current descriptor is not empty, append current descriptor to descriptors. Jump to the step labeled descriptor parser.
- Anything else
- Append c to current descriptor.
- In parens
-
Do the following, depending on the value of c:
- U+0029 RIGHT PARENTHESIS ())
- Append c to current descriptor. Set state to in descriptor.
- EOF
- Append current descriptor to descriptors. Jump to the step labeled descriptor parser.
- Anything else
- Append c to current descriptor.
- After descriptor
-
Do the following, depending on the value of c:
- Space character
- Stay in this state.
- EOF
- Jump to the step labeled descriptor parser.
- Anything else
- Set state to in descriptor. Set position to the previous character in input.
Advance position to the next character in input. Repeat this substep.
In order to be compatible with future additions, this algorithm supports multiple descriptors and descriptors with parens.
- Descriptor parser: Let error be no.
- Let width be absent.
- Let density be absent.
- Let future-compat-h be absent.
-
For each descriptor in descriptors, run the appropriate set of steps from the following list:
- If the descriptor consists of a valid non-negative integer followed by a U+0077 LATIN SMALL LETTER W character
-
-
If the user agent does not support the
sizes
attribute, let error be yes.A conforming user agent will support the
sizes
attribute. However, user agents typically implement and ship features in an incremental manner in practice. - If width and density are not both absent, then let error be yes.
- Apply the rules for parsing non-negative integers to the descriptor. If the result is zero, let error be yes. Otherwise, let width be the result.
-
- If the descriptor consists of a valid floating-point number followed by a U+0078 LATIN SMALL LETTER X character
-
- If width, density and future-compat-h are not all absent, then let error be yes.
-
Apply the rules for parsing floating-point number values to the descriptor. If the result is less than zero, let error be yes. Otherwise, let density be the result.
If density is zero, the intrinsic dimensions will be infinite. User agents are expected to have limits in how big images can be rendered, which is allowed by the hardware limitations clause.
- If the descriptor consists of a valid non-negative integer followed by a U+0068 LATIN SMALL LETTER H character
-
This is a parse error.
- If future-compat-h and density are not both absent, then let error be yes.
- Apply the rules for parsing non-negative integers to the descriptor. If the result is zero, let error be yes. Otherwise, let future-compat-h be the result.
- Anything else
- Let error be yes.
- If future-compat-h is not absent and width is absent, let error be yes.
- If error is still no, then append a new image source to candidates whose URL is url, associated with a width width if not absent and a pixel density density if not absent. Otherwise, there is a parse error.
- Return to the step labeled splitting loop.
When asked to parse a sizes attribute from an element, parse a comma-separated list of component values from the value of the element’s sizes
attribute
(or the empty string, if the attribute is absent),
and let unparsed sizes list be the result. [CSS-SYNTAX-3]
For each unparsed size in unparsed sizes list:
- Remove all consecutive <whitespace-token>s from the end of unparsed size. If unparsed size is now empty, that is a parse error; continue to the next iteration of this algorithm.
- If the last component value in unparsed size is a valid non-negative
<source-size-value>
, let size be its value and remove the component value from unparsed size. Any CSS function other than thecalc()
function is invalid. Otherwise, there is a parse error; continue to the next iteration of this algorithm. - Remove all consecutive <whitespace-token>s from the end of unparsed size. If unparsed size is now empty, return size and exit this algorithm. If this was not the last item in unparsed sizes list, that is a parse error.
- Parse the remaining component values in unparsed size as a <media-condition>. If it does not parse correctly, or it does parse correctly but the <media-condition> evaluates to false, continue to the next iteration of this algorithm. [MEDIAQ]
- Return size and exit this algorithm.
If the above algorithm exhausts unparsed sizes list without returning a size value, follow these steps:
- If width is not null, return a
<length>
with the value width and the unitpx
. - Return
100vw
.
A parse error for the algorithms above indicates a non-fatal mismatch between input and requirements. User agents are encouraged to expose parse errors somehow.
While a valid source size list only contains a bare <source-size-value>
(without an accompanying <media-condition>
)
as the last entry in the <source-size-list>
,
the parsing algorithm technically allows such at any point in the list,
and will accept it immediately as the size
if the preceding entries in the list weren’t used.
This is to enable future extensions,
and protect against simple author errors such as a final trailing comma.
An image source can have a density descriptor, a width descriptor, or no descriptor at all accompanying its URL. Normalizing a source set gives every image source a density descriptor.
When asked to normalize the source densities of a source set source set, the user agent must do the following:
- Let source size be source set’s source size.
-
For each image source in source set:
- If the image source has a density descriptor, continue to the next image source.
-
Otherwise, if the image source has a width descriptor, replace the width descriptor with a density descriptor with a value of the width descriptor divided by the source size and a unit of
x
.If the source size is zero, the density would be infinity, which results in the intrinsic dimensions being zero by zero.
- Otherwise, give the image source a density descriptor of
1x
.
The user agent may at any time run the following algorithm to update an img
element’s image in order to react to changes in the environment. (User agents are not
required to ever run this algorithm; for example, if the user is not looking at the page any
more, the user agent might want to wait until the user has returned to the page before determining
which image to use, in case the environment changes again in the meantime.)
User agents are encouraged to run this algorithm in particular when the user changes the viewport’s size
(e.g., by resizing the window or changing the page zoom),
and when an img
element is inserted into a document,
so that the density-corrected intrinsic width and height match the new viewport,
and so that the correct image is chosen when art direction is involved.
- in parallel await a stable state. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)
- ⌛ If the
img
element does not usesrcset
orpicture
, its node document is not the active document, has image data whose resource type ismultipart/x-mixed-replace
, or the pending request is not null, then abort this algorithm. - ⌛ Let selected source and selected pixel density be the URL and pixel density that results from selecting an image source, respectively.
- ⌛ If selected source is null, then abort these steps.
- ⌛ If selected source and selected pixel density are the same as the element’s last selected source and current pixel density, then abort these steps.
- ⌛ Parse selected source, relative to the element’s node document, and let absolute URL be the resulting URL string. If that is not successful, abort these steps.
- ⌛ Let corsAttributeState be the state of the element’s
crossorigin
content attribute. - ⌛ Let origin be the origin of the
img
element’s node document. - ⌛ Let client be the
img
element’s node document’sWindow
object’s environment settings object. - ⌛ Let key be a tuple consisting of absolute URL, corsAttributeState, and, if corsAttributeState is not No CORS, origin.
- ⌛ Let image request be a new image request whose current URL is absolute URL
- ⌛ Let the element’s pending request be image request.
- End the synchronous section, continuing the remaining steps in parallel.
-
If the list of available images contains an entry for key, then set image request’s image data to that of the entry. Continue to the next step.
Otherwise, run these substeps:
- Let request be the result of creating a potential-CORS request given absolute URL and corsAttributeState.
- Set request’s client to client, type to "
image
", and set request’s synchronous flag. - Let response be the result of fetching request.
- If response’s unsafe response is a network error or
if the image format is unsupported (as determined by applying the image sniffing rules, again as mentioned earlier),
or if the user agent is able to determine that image request’s image is corrupted in
some fatal way such that the image dimensions cannot be obtained, or if the resource type is
multipart/x-mixed-replace
, then let pending request be null and abort these steps. - Otherwise, response’s unsafe response is image
request’s image data. It can be either CORS-same-origin or CORS-cross-origin; this affects the origin of the image itself (e.g., when used on a
canvas
).
-
Queue a task to run the following substeps:
- If the
img
element has experienced relevant mutations since this algorithm started, then let pending request be null and abort these steps. - Let the
img
element’s last selected source be selected source and theimg
element’s current pixel density be selected pixel density. - Set image request to the completely available state.
- Add the image to the list of available images using the key key, with the ignore higher-layer caching flag set.
- Upgrade the pending request to the current request.
- Update the
img
element’s presentation appropriately. - Fire a simple event named
load
at theimg
element.
- If the
The task source for the tasks queued by algorithms in this section is the DOM manipulation task source.
What an img
element represents depends on the src
attribute and the alt
attribute.
- If the
src
attribute is set and thealt
attribute is set to the empty string -
The image is either decorative or supplemental to the rest of the content, redundant with some other information in the document.
If the image is available and the user agent is configured to display that image, then the element represents the element’s image data.
Otherwise, the element represents nothing, and may be omitted completely from the rendering. User agents may provide the user with a notification that an image is present but has been omitted from the rendering.
- If the
src
attribute is set and thealt
attribute is set to a value that isn’t empty -
The image is a key part of the content; the
alt
attribute gives a textual equivalent or replacement for the image.If the image is available and the user agent is configured to display that image, then the element represents the element’s image data.
Otherwise, the element represents the text given by the
alt
attribute. User agents may provide the user with a notification that an image is present but has been omitted from the rendering. - If the
src
attribute is set and thealt
attribute is not -
There is no textual equivalent of the image available.
If the image is available and the user agent is configured to display that image, then the element represents the element’s image data.
Otherwise, the user agent should display some sort of indicator that there is an image that is not being rendered, and may, if requested by the user, or if so configured, or when required to provide contextual information in response to navigation, provide caption information for the image, derived as follows:
- If the image is a descendant of a
figure
element that has a childfigcaption
element, and, ignoring thefigcaption
element and its descendants, thefigure
element has noText
node descendants other than inter-element whitespace, and no embedded content descendant other than theimg
element, then the contents of the first suchfigcaption
element are the caption information; abort these steps. - There is no caption information.
- If the image is a descendant of a
- If the
src
attribute is not set and either thealt
attribute is set to the empty string or thealt
attribute is not set at all -
The element represents nothing.
- Otherwise
-
The element represents the text given by the
alt
attribute.
The alt
attribute does not represent advisory information.
User agents must not present the contents of the alt
attribute
in the same way as content of the title
attribute.
User agents may always provide the user with the option to display any image, or to prevent any image from being displayed. User agents may also apply heuristics to help the user make use of the image when the user is unable to see it, e.g., due to a visual disability or because they are using a text terminal with no graphics capabilities. Such heuristics could include, for instance, optical character recognition (OCR) of text found within the image.
While user agents are encouraged to repair cases of missing alt
attributes, authors must not rely on such behavior. Requirements for providing text to act as an alternative for images are described
in detail below.
The contents of img
elements, if any, are ignored for the purposes of
rendering.
The usemap
attribute,
if present, can indicate that the image has an associated image map.
The ismap
attribute, when used on an element that is a descendant of an a
element with an href
attribute, indicates by its
presence that the element provides access to a server-side image
map. This affects how events are handled on the corresponding a
element.
The ismap
attribute is a boolean attribute. The attribute must not be specified
on an element that does not have an ancestor a
element
with an href
attribute.
The usemap
and ismap
attributes
can result in confusing behavior when used together with source
elements with the media
attribute specified
in a picture
element.
The img
element supports dimension
attributes.
The alt
, src
, srcset
and sizes
IDL attributes must reflect the
respective content attributes of the same name.
The crossOrigin
IDL attribute must reflect the crossorigin
content attribute.
The useMap
IDL attribute must reflect the usemap
content attribute.
The isMap
IDL attribute must reflect the ismap
content attribute.
- image .
width
[ = value ]- image .
height
[ = value ] - image .
-
These attributes return the actual rendered dimensions of the image, or zero if the dimensions are not known.
They can be set, to change the corresponding content attributes.
- image .
naturalWidth
- image .
naturalHeight
- image .
-
These attributes return the intrinsic dimensions of the image, or zero if the dimensions are not known.
- image .
complete
-
Returns true if the image has been completely downloaded or if no image is specified; otherwise, returns false.
- image .
currentSrc
-
Returns the image’s absolute URL.
- image = new
Image
( [ width [, height ] ] ) -
Returns a new
img
element, with thewidth
andheight
attributes set to the values passed in the relevant arguments, if applicable.
The IDL attributes width
and height
must return the rendered width and height of the
image, in CSS pixels, if the image is being rendered, and is being rendered to a
visual medium; or else the density-corrected intrinsic width and height of the image, in CSS pixels, if the image has intrinsic dimensions and is available but not being rendered to a visual medium; or else 0, if
the image is not available or does not have intrinsic dimensions. [CSS-2015]
On setting, they must act as if they reflected the respective content attributes of the same name.
The IDL attributes naturalWidth
and naturalHeight
must return
the density-corrected intrinsic width and height of the image, in CSS pixels, if the image has intrinsic dimensions and is available, or else 0. [CSS-2015]
The IDL attribute complete
must return true if
any of the following conditions is true:
- Both the
src
attribute and thesrcset
attribute are omitted. - The
srcset
attribute is omitted and thesrc
attribute’s value is the empty string. - The final task that is queued by the networking task source once the resource has been fetched has been queued.
- The
img
element is completely available. - The
img
element is broken.
Otherwise, the attribute must return false.
The value of complete
can thus change while
a script is executing.
The currentSrc
IDL attribute
must return the img
element’s current request’s current URL.
A constructor is provided for creating HTMLImageElement
objects (in addition to
the factory methods from DOM such as createElement()
): Image(width, height)
.
When invoked as a constructor, this must return a new HTMLImageElement
object (a new img
element). If the width argument is present, the new object’s width
content attribute must be set to width. If the height argument is also present, the new object’s height
content attribute must be set to height.
The element’s node document must be the active document of the browsing context of the Window
object on which the interface object of
the invoked constructor is found.
4.7.5.1. Requirements for providing text to act as an alternative for images
Text alternatives, [WCAG20] are a primary way of making visual information accessible, because they can be rendered through many sensory modalities (for example, visual, auditory or tactile) to match the needs of the user. Providing text alternatives allows the information to be rendered in a variety of ways by a variety of user agents. For example, a person who cannot see a picture can hear the text alternative read aloud using synthesized speech.
The alt
attribute on images is a very important accessibility attribute.
Authoring useful alt
attribute content requires the author to
carefully consider the context in which the image appears and the function that
image may have in that context.
The guidance included here addresses the most common ways authors use images. Additional guidance and techniques are available in Resources on Alternative Text for Images.
4.7.5.1.1. Examples of scenarios where users benefit from text alternatives for images
- They have a very slow connection and are browsing with images disabled.
- They have a vision impairment and use text to speech software.
- They have a cognitive impairment and use text to speech software.
- They are using a text-only browser.
- They are listening to the page being read out by a voice Web browser.
- They have images disabled to save on download costs.
- They have problems loading images or the source of an image is wrong.
4.7.5.1.2. General guidelines
Except where otherwise specified, the alt
attribute must be specified and its value must not be empty;
the value must be an appropriate functional replacement for the image. The specific requirements for the alt
attribute content depend on the image’s function in the page, as described in the following sections.
To determine an appropriate text alternative it is important to think about why an image is being included in a page. What is its purpose? Thinking like this will help you to understand what is important about the image for the intended audience. Every image has a reason for being on a page, because it provides useful information, performs a function, labels an interactive element, enhances aesthetics or is purely decorative. Therefore, knowing what the image is for, makes writing an appropriate text alternative easier.
4.7.5.1.3. A link or button containing nothing but an image
When an a
element that is a hyperlink, or a button
element, has no text content
but contains one or more images, include text in the alt
attribute(s) that together convey the purpose of the link or button.
alt
attributes of the images:
<ul> <li><button><img src="b.png" alt="Bold"></button></li> <li><button><img src="i.png" alt="Italics"></button></li> <li><button><img src="strike.png" alt="Strike through"></button></li> <li><button><img src="blist.png" alt="Bulleted list"></button></li> <li><button><img src="nlist.png" alt="Numbered list"></button></li> </ul>
<a href="https://w3.org"> <img src="images/w3c_home.png" width="72" height="48" alt="W3C web site"> </a>
<a href="https://w3.org"> <img src="images/w3c_home.png" width="72" height="48" alt="W3C home"> </a>
Depending on the context in which an image of a logo is used it could be appropriate to provide an indication, as part of the text alternative, that the image is a logo. Refer to section §4.7.5.1.19 Logos, insignia, flags, or emblems.
<a href="preview.html"> <img src="images/preview.png" width="32" height="30" alt="Print preview."> </a>
<button> <img src="images/search.png" width="74" height="29" alt="Search"> </button>
alt
attribute of the first image.
<a href="pipco-home.html"> <img src="pip.gif" alt="PIP CO home"><img src="co.gif" alt=""> </a>
4.7.5.1.4. Graphical Representations: Charts, diagrams, graphs, maps, illustrations
Users can benefit when content is presented in graphical form, for example as a flowchart, a diagram, a graph, or a map showing directions. Users who are unable to view the image also benefit when content presented in a graphical form is provided in a text-based format. Software agents that process text content, but cannot automatically process images (e.g. translation services, many search engines), also benefit from a text-based description.
alt
attribute representing the data shown in the pie chart:
<img src="piechart.gif" alt="Pie chart: Browser Share - Internet Explorer 25%, Firefox 40%, Chrome 25%, Safari 6% and Opera 4%.">
alt
attribute content labels the image.
<p id="graph7">According to a recent study Firefox has a 40% browser share, Internet Explorer has 25%, Chrome has 25%, Safari has 6% and Opera has 4%.</p> <p><img src="piechart.gif" alt="The browser shares as a pie chart."></p>
It can be seen that when the image is not available, for example because the src
attribute value is incorrect, the text alternative provides the user with a brief description of
the image content:
In cases where the text alternative is lengthy, more than a sentence or two, or would benefit
from the use of structured markup, provide a brief description or label using the alt
attribute, and an associated text alternative.
alt
attribute, in this case the text alternative is a description of the link target
as the image is the sole content of a link. The link points to a description, within the same document, of the
process represented in the flowchart.
<a href="#desc"><img src="flowchart.gif" alt="Flowchart: Dealing with a broken lamp."></a> ... ... <div id="desc"> <h2>Dealing with a broken lamp</h2> <ol> <li>Check if it’s plugged in, if not, plug it in.</li> <li>If it still doesn’t work; check if the bulb is burned out. If it is, replace the bulb.</li> <li>If it still doesn’t work; buy a new lamp.</li> </ol> </div>
alt
attribute as the information is a data set. Instead a
structured text alternative is provided below the image in the form of a data table using the data that is represented
in the chart image.
Indications of the highest and lowest rainfall for each season have been included in the table, so trends easily identified in the chart are also available in the data table.
United Kingdom | Japan | Australia | |
---|---|---|---|
Spring | 5.3 (highest) | 2.4 | 2 (lowest) |
Summer | 4.5 (highest) | 3.4 | 2 (lowest) |
Autumn | 3.5 (highest) | 1.8 | 1.5 (lowest) |
Winter | 1.5 (highest) | 1.2 | 1 (lowest) |
<figure> <figcaption>Rainfall Data</figcaption> <img src="rainchart.gif" alt="Bar chart: average rainfall by Country and Season. Full description in Table below."> <table id="table-4"> <caption>Rainfall in millimetres by Country and Season.</caption> <tr><td><th scope="col">UK <th scope="col">Japan<th scope="col">Australia</tr> <tr><th scope="row">Spring <td>5.5 (highest)<td>2.4 <td>2 (lowest)</tr> <tr><th scope="row">Summer <td>4.5 (highest)<td>3.4<td>2 (lowest)</tr> <tr><th scope="row">Autumn <td>3.5 (highest) <td>1.8 <td>1.5 (lowest)</tr> <tr><th scope="row">Winter <td>1.5 (highest) <td>1.2 <td>1 lowest</tr> </table> </figure>
The figure
element is used to group the Bar Chart image and data table.
The figcaption
element provides a caption for the grouped content.
For any of the examples in this section the details
and summary
elements could be used so that the text descriptions for the images are only displayed on demand:
<figure> <img src="flowchart.gif" alt="Flowchart: Dealing with a broken lamp."> <details> <summary>Dealing with a broken lamp</summary> <ol> <li>Check if it’s plugged in, if not, plug it in.</li> <li>If it still doesn’t work; check if the bulb is burned out. If it is, replace the bulb.</li> <li>If it still doesn’t work; buy a new lamp.</li> </ol> </details> </figure>
The details
and summary
elements are not currently well supported by
browsers, until such times they are supported, if used, you will need to use scripting to
provide the functionality. There are a number of scripted Polyfills and scripted custom
controls available, in popular JavaScript UI widget libraries, which provide similar
functionality.
4.7.5.1.5. Images of text
Sometimes, an image only contains text, and the purpose of the image
is to display text using visual effects and /or fonts. It is strongly recommended that text styled using CSS be used, but if this is not possible, provide
the same text in the alt
attribute as is in the image.
<h1><img src="gethappy.gif" alt="Get Happy!"></h1>
<p><img src="sale.gif" alt="The BIG sale ...ends Friday."></p>
In situations where there is also a photo or other graphic along with the image of text, ensure that the words in the image text are included in the text alternative, along with any other description of the image that conveys meaning to users who can view the image, so the information is also available to users who cannot view the image.
Only 5.99!
<p>Only <img src="euro.png" alt="euro ">5.99!
An image should not be used if Unicode characters would serve an identical purpose. Only when the text cannot be directly represented using Unicode, e.g., because of decorations or because the character is not in the Unicode character set (as in the case of gaiji), would an image be appropriate.
If an author is tempted to use an image because their default system font does not support a given character, then Web Fonts are a better solution than images.
![O](images/fancyO.png)
<p><img src="initials/fancyO.png" alt="O">nce upon a time and a long long time ago...
4.7.5.1.6. Images that include text
Sometimes, an image consists of a graphics such as a chart and associated text. In this case it is recommended that the text in the image is included in the text alternative.
<p><img src="figure1.gif" alt="Figure 1. Distribution of Articles by Journal Category. Pie chart: Language=68%, Education=14% and Science=18%."></p>
alt
attribute
and a longer text alternative in text. The figure
and figcaption
elements are used to associate the longer text alternative with the image. The alt
attribute is used
to label the image.
<figure> <img src="figure1.gif" alt="Figure 1"> <figcaption><strong>Figure 1.</strong> Distribution of Articles by Journal Category. Pie chart: Language=68%, Education=14% and Science=18%.</figcaption> </figure>
The advantage of this method over the previous example is that the text alternative
is available to all users at all times. It also allows structured mark up to be used in the text
alternative, where as a text alternative provided using the alt
attribute does not.
4.7.5.1.7. Images that enhance the themes or subject matter of the page content
An image that isn’t discussed directly by the surrounding text but still has
some relevance can be included in a page using the img
element. Such images
are more than mere decoration, they may augment the themes or subject matter of the page
content and so still form part of the content. In these cases, it is recommeneded that a
text alternative be provided.
alt
attribute and
a link below the image to a longer description located at the bottom of the document. At the end
of the longer description there is also a link to further information about the painting.
<header> <h1>The Lady of Shalott</h1> <p>A poem by Alfred Lord Tennyson</p> </header> <img src="shalott.jpeg" alt="Painting - a young woman with long hair, sitting in a wooden boat. Full description below."> <p><a href="#des">Description of the painting</a>.</p> <!-- Full Recitation of Alfred, Lord Tennyson’s Poem. --> ... ... ... <p id="des">The woman in the painting is wearing a flowing white dress. A large piece of intricately patterned fabric is draped over the side. In her right hand she holds the chain mooring the boat. Her expression is mournful. She stares at a crucifix lying in front of her. Beside it are three candles. Two have blown out. <a href="https://bit.ly/5HJvVZ">Further information about the painting</a>.</p>
This example illustrates the provision of a text alternative identifying an image as a photo of the main subject of a page.
<img src="orateur_robin_berjon.png" alt="Portrait photo(black and white) of Robin."> <h1>Robin Berjon</h1> <p>What more needs to be said?</p>
4.7.5.1.8. A graphical representation of some of the surrounding text
In many cases, the image is actually just supplementary, and its presence merely reinforces the
surrounding text. In these cases, the alt
attribute must be
present but its value must be the empty string.
In general, an image falls into this category if removing the image doesn’t make the page any less useful, but including the image makes it a lot easier for users of visual browsers to understand the concept.
alt
attribute, and
there is a link after the image. The link points to a page containing information about the painting.
The Lady of Shalott
A poem by Alfred Lord Tennyson.
Full recitation of Alfred, Lord Tennyson’s poem.
<header><h1>The Lady of Shalott</h1> <p>A poem by Alfred Lord Tennyson</p></header> <figure> <img src="shalott.jpeg" alt="Painting: a woman in a white flowing dress, sitting in a small boat."> <p><a href="https://bit.ly/5HJvVZ">About this painting.</a></p> </figure> <!-- Full Recitation of Alfred, Lord Tennyson’s Poem. -->
4.7.5.1.9. A purely decorative image that doesn’t add any information
Purely decorative images are visual enhancements, decorations or embellishments that provide no function or information beyond aesthetics to users who can view the images.
Mark up purely decorative images so they can be ignored by assistive technology by using an empty alt
attribute (alt=""
). While it is not unacceptable to include decorative images inline,
it is recommended if they are purely decorative to include the image using CSS.
alt
attribute is used.
Clara’s Blog Welcome to my blog...
<header> <div><img src="border.gif" alt="" width="400" height="30"></div> <h1>Clara’s Blog</h1> </header> <p>Welcome to my blog...</p>
4.7.5.1.10. Inline images
When images are used inline as part of the flow of text in a sentence, provide a word or phrase as a text alternative which makes sense in the context of the sentence it is apart of.
![love](images/heart.png)
I <img src="heart.png" alt="love"> you.
My breaks.
My <img src="heart.png" alt="heart"> breaks.
4.7.5.1.11. A group of images that form a single larger picture with no links
When a picture has been sliced into smaller image files that are then displayed
together to form the complete picture again, include a text alternative for one
of the images using the alt
attribute as per the relevant relevant
guidance for the picture as a whole, and then include an empty alt
attribute on the other images.
alt
attribute of the first image.
<img src="pip.gif" alt="PIP CO"><img src="co.gif" alt="">
alt
attributes. ![3 out of 5.](images/rating.png)
<p>Rating: <img src="1" alt="3 out of 5"> <img src="1" alt=""><img src="1" alt=""> <img src="0" alt=""><img src="0" alt=""> </p>
4.7.5.1.12. Image maps
If animg
element has a usemap
attribute which references a map
element containing area
elements that have href
attributes, the img
is considered to be interactive content.
In such cases, always provide a text alternative for the image using the alt
attribute.
alt
attribute on each
of the area
elements provides text describing the content of the target page of each linked region:
<p>View houses for sale in North Katoomba or South Katoomba:</p> <p><img src="imagemap.png" width="209" alt="Map of Katoomba" height="249" usemap="#Map"> <map name="Map"> <area shape="poly" coords="78,124,124,10,189,29,173,93,168,132,136,151,110,130" href="north.html" alt="Houses in North Katoomba"> <area shape="poly" coords="66,63,80,135,106,138,137,154,167,137,175,133,144,240,49,223,17,137,17,61" alt="Houses in South Katoomba" href="south.html"> </map>
4.7.5.1.13. A group of images that form a single larger picture with links
Sometimes, when you create a composite picture from multiple images, you may wish to
link one or more of the images. Provide an alt
attribute
for each linked image to describe the purpose of the link.
<h1>The crocoduck</h1> <p>You encounter a strange creature called a "crocoduck". The creature seems angry! Perhaps some friendly stroking will help to calm it, but be careful not to stroke any crocodile parts. This would just enrage the beast further.</p> <a href="?stroke=head"><img src="crocoduck1.png" alt="Stroke crocodile’s angry, chomping head"></a> <a href="?stroke=body"><img src="crocoduck2.png" alt="Stroke duck’s soft, feathery body"></a>
4.7.5.1.14. Images of Pictures
Images of pictures or graphics include visual representations of objects, people, scenes, abstractions, etc. This non-text content, [WCAG20] can convey a significant amount of information visually or provide a specific sensory experience, [WCAG20] to a sighted person. Examples include photographs, paintings, drawings and artwork.
An appropriate text alternative for a picture is a brief description, or name [WCAG20]. As in all text alternative authoring decisions, writing suitable text alternatives for pictures requires
human judgment. The text value is subjective to the context where the image is used and the page author’s writing style. Therefore,
there is no single "right" or "correct" piece of alt
text for any particular image. In addition to providing a short text
alternative that gives a brief description of the non-text content, also providing supplemental content through another means when
appropriate may be useful.
img
element’s alt
attribute. It also has a caption provided by including
the img
element in a figure
element and using a figcaption
element to identify the caption text.
Lola prefers a bath to a shower.
<figure> <img src="664aef.jpg" alt="Lola the cat sitting under an umbrella in the bath tub."> <figcaption>Lola prefers a bath to a shower.</figcaption> </figure>
alt
attribute which gives users who cannot view the image a sense
of what the image is. It also has a caption provided by including the img
element in a figure
element and using a figcaption
element to identify the caption text.
The first of the ten cards in the Rorschach test.
<figure> <img src="Rorschach1.jpg" alt="An abstract, freeform, vertically symmetrical, black inkblot on a light background."> <figcaption>The first of the ten cards in the Rorschach test.</figcaption> </figure>
4.7.5.1.15. Webcam images
Webcam images are static images that are automatically updated periodically. Typically the images are from a fixed viewpoint, the images may update on the page automatically as each new image is uploaded from the camera or the user may be required to refresh the page to view an updated image. Examples include traffic and weather cameras.
figure
and figcaption
elements. As the image is provided to give a visual indication of the current weather near a building,
a link to a local weather forecast is provided, as with automatically generated and uploaded webcam images it may be impractical to
provide such information as a text alternative.
The text of the alt
attribute includes a prose version of the timestamp, designed to make the text more
understandable when announced by text to speech software. The text alternative also includes a description of some aspects
of what can be seen in the image which are unchanging, although weather conditions and time of day change.
View from the top of Sopwith house, looking towards North Kingston. This image is updated every hour.
View the latest weather details for Kingston upon Thames.
<figure> <img src="webcam1.jpg" alt="Sopwith house weather cam. Taken on the 21/04/10 at 11:51 and 34 seconds. In the foreground are the safety rails on the flat part of the roof. Nearby there are low rize industrial buildings, beyond are blocks of flats. In the distance there’s a church steeple."> <figcaption>View from Sopwith house, looking towards north Kingston. This image is updated every hour.</figcaption> </figure> <p>View the <a href="https://news.bbc.co.uk/weather/forecast/4296?area=Kingston">latest weather details</a> for Kingston upon Thames.</p>
4.7.5.1.16. When a text alternative is not available at the time of publication
In some cases an image is included in a published document, but the author is unable to provide an appropriate text alternative.
In such cases the minimum requirement is to provide a caption for the image using the figure
and figcaption
elements under the following conditions:
- The
img
element is in afigure
element - The
figure
element contains afigcaption
element - The
figcaption
element contains content other than inter-element whitespace - Ignoring the
figcaption
element and its descendants, thefigure
element has noText
node descendants other than inter-element whitespace, and no embedded content descendant other than theimg
element.
In other words, the only content of the figure
is an img
element and a figcaption
element, and the figcaption
element must include (caption) content.
Such cases are to be kept to an absolute
minimum. If there is even the slightest possibility of the author
having the ability to provide real alternative text, then it would
not be acceptable to omit the alt
attribute.
The caption text in the example below is not a suitable text alternative and is not conforming to the Web Accessibility Guidelines 2.0. [WCAG20]
![no text alternative provided](images/clara.png)
clara.jpg, taken on 12/11/2010.
<figure> <img src="clara.jpg"> <figcaption>clara.jpg, taken on 12/11/2010.</figcaption> </figure>
Notice that even in this example, as much useful information
as possible is still included in the figcaption
element.
alt
attribute.
Eloisa with Princess Belle
<figure> <img src="elo.jpg"> <figcaption>Eloisa with Princess Belle</figcaption> </figure>
<table> <tr><tr> <th> Image <th> Description<tr> <td> <figure> <img src="2421.png"> <figcaption>Image 640 by 100, filename 'banner.gif'</figcaption> </figure> <td> <input name="alt2421"> <tr> <td> <figure> <img src="2422.png"> <figcaption>Image 200 by 480, filename 'ad3.gif'</figcaption> </figure> <td> <input name="alt2422"> </table>
Since some users cannot use images at all (e.g., because they are blind) the alt
attribute is only allowed to be omitted when no text
alternative is available and none can be made available, as in the above examples.
4.7.5.1.17. An image not intended for the user
Generally authors should avoid using img
elements
for purposes other than showing images.
If an img
element is being used for purposes other
than showing an image, e.g., as part of a service to count page
views, use an empty alt
attribute.
img
element used to collect web page statistics.
The alt
attribute is empty as the image has no meaning.
<img src="https://server3.stats.com/count.pl?NeonMeatDream.com" width="0" height="0" alt="">
It is recommended for the example use above the width
and height
attributes be set to zero.
alt
attribute is empty as the image has no meaning.
<img src="spacer.gif" width="10" height="10" alt="">
It is recommended that CSS be used to position content instead of img
elements.
4.7.5.1.18. Icon Images
An icon is usually a simple picture representing a program, action, data file or a concept. Icons are intended to help users of visual browsers to recognize features at a glance.
Use an empty alt
attribute when an icon is supplemental to
text conveying the same meaning.
alt
text.
<a href="home.html"><img src="home.gif" width="15" height="15" alt="">Home</a>
Where images are used in this way, it would also be appropriate to add the image using CSS.
#home:before { content: url(home.png); } <a href="home.html" id="home">Home</a>
img
element is given an empty alt
attribute.
Warning! Your session is about to expire.
<p><img src="warning.png" width="15" height="15" alt=""> <strong>Warning!</strong> Your session is about to expire</p>
When an icon conveys additional information not available in text, provide a text alternative.
Your session is about to expire.
<p><img src="warning.png" width="15" height="15" alt="Warning!"> Your session is about to expire</p>
4.7.5.1.19. Logos, insignia, flags, or emblems
Many pages include logos, insignia, flags, or emblems, which stand for a company, organization, project, band, software package, country, or other entity. What can be considered as an appropriate text alternative depends upon, like all images, the context in which the image is being used and what function it serves in the given context.
If a logo is the sole content of a link, provide a brief description of the link target in the alt
attribute.
<a href="https://w3c.github.io/html/"> <img src="HTML5_Logo.png" alt="HTML 5.1 specification"></a>
If a logo is being used to represent the entity, e.g., as a page heading, provide the name of the entity being represented by the logo as the text alternative.
and other developer resources
<h2><img src="images/webplatform.png" alt="WebPlatform.org"> and other developer resources<h2>
The text alternative in the example above could also include the word "logo" to describe the
type of image content. If so, it is suggested that square brackets be used to delineate this
information: alt="[logo] WebPlatform.org"
.
If a logo is being used next to the name of the what that it represents, then the logo is
supplemental. Include an empty alt
attribute as the text alternative is already
provided.
WebPlatform.org
<img src="images/webplatform1.png" alt=""> WebPlatform.org
If the logo is used alongside text discussing the subject or entity the logo represents, then provide a text alternative which describes the logo.
HTML is a language for structuring and presenting content for the World Wide Web, a core technology of the Internet. It is the latest revision of the HTML standard (originally created in 1990 and most recently standardized as HTML 4.01 in 1997) and currently remains under development. Its core aims have been to improve the language with support for the latest multimedia while keeping it easily readable by humans and consistently understood by computers and devices (web browsers, parsers etc.).
<p><img src="HTML5_Logo.png" alt="HTML5 logo: Shaped like a shield with the text 'HTML' above and the numeral '5' prominent on the face of the shield."></p> Information about HTML
4.7.5.1.20. CAPTCHA Images
CAPTCHA stands for "Completely Automated Public Turing test to tell Computers and Humans Apart". CAPTCHA images are used for security purposes to confirm that content is being accessed by a person rather than a computer. This authentication is done through visual verification of an image. CAPTCHA typically presents an image with characters or words in it that the user is to re-type. The image is usually distorted and has some noise applied to it to make the characters difficult to read.
To improve the accessibility of CAPTCHA provide text alternatives that identify and describe the purpose of the image, and provide alternative forms of the CAPTCHA using output modes for different types of sensory perception. For instance provide an audio alternative along with the visual image. Place the audio option right next to the visual one. This helps but is still problematic for people without sound cards, the deaf-blind, and some people with limited hearing. Another method is to include a form that asks a question along with the visual image. This helps but can be problematic for people with cognitive impairments.
It is strongly recommended that alternatives to CAPTCHA be used, as all forms of CAPTCHA introduce unacceptable barriers to entry for users with disabilities. Further information is available in Inaccessibility of CAPTCHA.
alt
attribute provides instructions for a user in the case where she cannot
access the image content.
Example code:
<img src="captcha.png" alt="If you cannot view this image an audio challenge is provided."> <!-- audio CAPTCHA option that allows the user to listen and type the word --> <!-- form that asks a question -->
4.7.5.1.21. An image in a picture
element
The picture
element and any source
elements it contains have no semantics for users,
only the img
element or its text alternative is displayed to users. Provide a text alternative for an img
element without regard to it being within a picture
element. Refer to Requirements for providing text to act as an alternative for images for more information on how to provide
useful alt
text for images.
Art directed images that rely on picture
need to depict
the same content (irrespective of size, pixel density, or any other discriminating factor). Therefore the appropriate
text alternative for an image will always be the same irrespective of which source file ends up being chosen by the browser.
<h2>Is it a ghost?</h2> <picture> <source media="(min-width: 32em)" srcset="large.jpg"> <img src="small.jpg" alt="Reflection of a girls face in a train window."> </picture>
The large and small versions (both versions are displayed for demonstration purposes) of
the image portray the same scene: Reflection of a girls face in a train window,
while the small version (displayed on smaller screens) is cropped, this does not effect the subject matter
or the appropriateness of the alt
text.
4.7.5.1.22. Guidance for markup generators
Markup generators (such as WYSIWYG authoring tools) should, wherever possible, obtain alternative text from their users. However, it is recognized that in many cases, this will not be possible.
For images that are the sole contents of links, markup generators should examine the link target to determine the title of the target, or the URL of the target, and use information obtained in this manner as the alternative text.
For images that have captions, markup generators should use the figure
and figcaption
elements to provide the image’s caption.
As a last resort, implementors should either set the alt
attribute to the empty string, under
the assumption that the image is a purely decorative image that
doesn’t add any information but is still specific to the surrounding
content, or omit the alt
attribute
altogether, under the assumption that the image is a key part of the
content.
Markup generators may specify a generator-unable-to-provide-required-alt
attribute on img
elements for which they have been
unable to obtain a text alternative and for which they have therefore
omitted the alt
attribute. The
value of this attribute must be the empty string. Documents
containing such attributes are not conforming, but conformance
checkers will silently ignore this error.
This is intended to avoid markup generators from
being pressured into replacing the error of omitting the alt
attribute with the even more
egregious error of providing phony text alternatives, because
state-of-the-art automated conformance checkers cannot distinguish
phony text alternatives from correct text alternatives.
Markup generators should generally avoid using the image’s own file name as the text alternative. Similarly, markup generators should avoid generating text alternatives from any content that will be equally available to presentation user agents (e.g., Web browsers).
This is because once a page is generated, it will typically not be updated, whereas the browsers that later read the page can be updated by the user, therefore the browser is likely to have more up-to-date and finely-tuned heuristics than the markup generator did when generating the page.
4.7.5.1.23. Guidance for conformance checkers
A conformance checker must report the lack of an alt
attribute as an error unless one
of the conditions listed below applies:
-
The
img
element is in afigure
element that satisfies the conditions described above. -
The
img
element has a (non-conforming)generator-unable-to-provide-required-alt
attribute whose value is the empty string. A conformance checker that is not reporting the lack of analt
attribute as an error must also not report the presence of the emptygenerator-unable-to-provide-required-alt
attribute as an error. (This case does not represent a case where the document is conforming, only that the generator could not determine appropriate alternative text — validators are not required to show an error in this case, because such an error might encourage markup generators to include bogus alternative text purely in an attempt to silence validators. Naturally, conformance checkers may report the lack of analt
attribute as an error even in the presence of thegenerator-unable-to-provide-required-alt
attribute; for example, there could be a user option to report all conformance errors even those that might be the more or less inevitable result of using a markup generator.)
4.7.6. The iframe
element
- Categories:
- Flow content.
- Phrasing content.
- Embedded content.
- Interactive content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where embedded content is expected.
- Content model:
- Text that conforms to the requirements given in the prose.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
src
- Address of the resourcesrcdoc
- A document to render in theiframe
name
- Name of nested browsing contextsandbox
- Security rules for nested contentallowfullscreen
- Whether to allow theiframe
’s contents to userequestFullscreen()
width
- Horizontal dimensionheight
- Vertical dimension - Allowed ARIA role attribute values:
application
,document
, orimg
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLIFrameElement : HTMLElement { attribute DOMString src; attribute DOMString srcdoc; attribute DOMString name; [PutForwards=value] readonly attribute DOMTokenList sandbox; attribute boolean allowFullscreen; attribute DOMString width; attribute DOMString height; readonly attribute Document? contentDocument; readonly attribute WindowProxy? contentWindow; };
The iframe
element represents a nested browsing context.
The src
attribute gives the address of a page
that the nested browsing context is to contain. The attribute, if present, must be a valid non-empty URL potentially surrounded by spaces.
The srcdoc
attribute gives the content of
the page that the nested browsing context is to contain. The value of the attribute
is the source of an iframe
srcdoc
document.
The srcdoc
attribute, if present, must have a value
using the HTML syntax that consists of the following syntactic components, in the
given order:
- Any number of comments and space characters.
- Optionally, a DOCTYPE.
- Any number of comments and space characters.
- The root element, in the form of an
html
element. - Any number of comments and space characters.
For iframe
elements in XML documents, the srcdoc
attribute, if present, must have a value that matches the
production labeled document
in the XML specification. [XML]
srcdoc
attribute in conjunction
with the sandbox
attributes described below to provide users of user
agents that support this feature with an extra layer of protection from script injection in the
blog post comments:
<article> <h1>I got my own magazine!</h1> <p>After much effort, I’ve finally found a publisher, and so now I have my own magazine! Isn’t that awesome?! The first issue will come out in September, and we have articles about getting food, and about getting in boxes, it’s going to be great!</p> <footer> <p>Written by <a href="/users/cap">cap</a>, 1 hour ago. </footer> <article> <footer> Thirteen minutes ago, <a href="/users/ch">ch</a> wrote: </footer> <iframe sandbox srcdoc="<p>did you get a cover picture yet?"></iframe> </article> <article> <footer> Nine minutes ago, <a href="/users/cap">cap</a> wrote: </footer> <iframe sandbox srcdoc="<p>Yeah, you can see it <a href="/gallery?mode=cover&amp;page=1">in my gallery</a>."></iframe> </article> <article> <footer> Five minutes ago, <a href="/users/ch">ch</a> wrote: </footer> <iframe sandbox srcdoc="<p>hey that’s earl’s table. <p>you should get earl&amp;me on the next cover."></iframe> </article>
Notice the way that quotes have to be escaped (otherwise the srcdoc
attribute would end prematurely), and the way raw
ampersands (e.g., in URLs or in prose) mentioned in the sandboxed content have to be doubly escaped — once so that the ampersand is preserved when originally parsing
the srcdoc
attribute, and once more to prevent the
ampersand from being misinterpreted when parsing the sandboxed content.
Furthermore, notice that since the DOCTYPE is optional in iframe
srcdoc
documents, and the html
, head
, and body
elements have optional
start and end tags, and the title
element is also optional in iframe
srcdoc
documents, the markup in a srcdoc
attribute can be
relatively succinct despite representing an entire document, since only the contents of the body
element need appear literally in the syntax. The other elements are still
present, but only by implication.
In the HTML syntax, authors need only remember to use U+0022
QUOTATION MARK characters (") to wrap the attribute contents and then to escape all U+0022
QUOTATION MARK (") and U+0026 AMPERSAND (&) characters, and to specify the sandbox
attribute, to ensure safe embedding of content.
Due to restrictions of the XHTML syntax, in XML the U+003C LESS-THAN SIGN character (<) needs to be escaped as well. In order to prevent attribute-value normalization, some of XML’s whitespace characters — specifically U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED (LF), and U+000D CARRIAGE RETURN (CR) — also need to be escaped. [XML]
If the src
attribute and the srcdoc
attribute are both specified together, the srcdoc
attribute takes priority. This allows authors to provide
a fallback URL for legacy user agents that do not support the srcdoc
attribute.
When an iframe
element is inserted into a document that has a browsing context, the user agent must create a nested browsing context, and
then process the iframe
attributes for the "first time".
When an iframe
element is removed from a document, the user agent must discard the nested browsing context, if any.
This happens without any unload
events firing
(the nested browsing context and its Document
are discarded, not unloaded).
Whenever an iframe
element with a nested browsing context has its srcdoc
attribute set, changed, or removed, the user agent
must process the iframe
attributes.
Similarly, whenever an iframe
element with a nested browsing context but with no srcdoc
attribute specified has its src
attribute set, changed, or removed, the user agent must process the iframe
attributes.
When the user agent is to process the iframe
attributes, it must run
the first appropriate steps from the following list:
- If the
srcdoc
attribute is specified -
Navigate the element’s child browsing context to a new response whose url list consists of about:srcdoc, header list consists of
Content-Type
/text/html
, body is the value of the attribute, CSP list is the CSP list of theiframe
element’s node document, and HTTPS state is the HTTPS state of theiframe
element’s node document.The resulting
Document
must be considered aniframe
srcdoc
document. - Otherwise, if the element has no
src
attribute specified, and the user agent is processing theiframe
’s attributes for the "first time" -
Queue a task to run the iframe load event steps.
The task source for this task is the DOM manipulation task source.
- Otherwise
-
-
If the element has no
src
attribute specified, or its value is the empty string, let url be the string "about:blank
".Otherwise, parse the value of the
src
attribute, relative to theiframe
element.If that is not successful, then let url be the string "
about:blank
". Otherwise, let url be the resulting URL string. -
If there exists an ancestor browsing context whose active document’s address, ignoring fragment identifiers, is equal to url, then abort these steps.
-
Navigate the element’s child browsing context to url.
-
Furthermore, if the active document of the element’s child browsing context before such a navigation was not completely loaded at the time of the new navigation, then the navigation must be completed with replacement enabled.
Similarly, if the child browsing context’s session history contained
only one Document
when the process the iframe
attributes algorithm was invoked, and that was the about:blank
Document
created
when the child browsing context was created, then any navigation required of the user agent in that algorithm must be completed
with replacement enabled.
When a Document
in an iframe
is marked as completely
loaded, the user agent must run the iframe load event steps in parallel.
A load
event is also fired at the iframe
element when it is created if no other data is loaded in it.
Each Document
has an iframe load in progress flag and a mute
iframe load flag. When a Document
is created, these flags must be unset for
that Document
.
The iframe load event steps are as follows:
- Let child document be the active document of the
iframe
element’s nested browsing context. - If child document has its mute iframe load flag set, abort these steps.
- Set child document’s iframe load in progress flag.
- Fire a simple event named
load
at theiframe
element. - Unset child document’s iframe load in progress flag.
This, in conjunction with scripting, can be used to probe the URL space of the local network’s HTTP servers. User agents may implement cross-origin access control policies that are stricter than those described above to mitigate this attack, but unfortunately such policies are typically not compatible with existing Web content.
When the iframe
’s browsing context’s active document is
not ready for post-load tasks, and when anything in the iframe
is delaying the load event of the iframe
’s browsing context’s active document, and when the iframe
’s browsing context is in the delaying load
events
mode, the iframe
must delay the load event of its document.
If, during the handling of the load
event, the browsing context in the iframe
is again navigated, that will further delay the load event.
If, when the element is created, the srcdoc
attribute is not set, and the src
attribute is either also not set or set but its value cannot be resolved, the browsing context will remain at the initial about:blank
page.
If the user navigates away from this page, the iframe
’s corresponding WindowProxy
object will proxy new Window
objects for new Document
objects, but the src
attribute will not change.
The name
attribute, if present, must be a valid browsing context name. The given value is used to name the nested browsing context. When the browsing context is created, if the attribute
is present, the browsing context name must be set to the value of this attribute;
otherwise, the browsing context name must be set to the empty string.
Whenever the name
attribute is set, the nested browsing context’s name must be changed to
the new value. If the attribute is removed, the browsing context name must be set to
the empty string.
The sandbox
attribute, when specified,
enables a set of extra restrictions on any content hosted by the iframe
. Its value
must be an unordered set of unique space-separated tokens that are ASCII
case-insensitive. The allowed values are allow-forms
, allow-pointer-lock
, allow-popups
, allow-same-origin
, allow-scripts
, and allow-top-navigation
.
When the attribute is set, the content is treated as being from a unique origin,
forms, scripts, and various potentially annoying APIs are disabled, links are prevented from
targeting other browsing contexts, and plugins are secured.
The allow-same-origin
keyword causes
the content to be treated as being from its real origin instead of forcing it into a unique
origin; the allow-top-navigation
keyword allows the content to navigate its top-level browsing context;
and the allow-forms
, allow-pointer-lock
, allow-popups
and allow-scripts
keywords re-enable forms, the
pointer lock API, popups, and scripts respectively. [POINTERLOCK]
Setting both the allow-scripts
and allow-same-origin
keywords together when the
embedded page has the same origin as the page containing the iframe
allows the embedded page to simply remove the sandbox
attribute and then reload itself, effectively breaking out of the sandbox altogether.
These flags only take effect when the nested browsing context of
the iframe
is navigated. Removing them, or removing the
entire sandbox
attribute, has no effect on an
already-loaded page.
Potentially hostile files should not be served from the same server as the file
containing the iframe
element. Sandboxing hostile content is of minimal help if an
attacker can convince the user to just visit the hostile content directly, rather than in the iframe
. To limit the damage that can be caused by hostile HTML content, it should be
served from a separate dedicated domain. Using a different domain ensures that scripts in the
files are unable to attack the site, even if the user is tricked into visiting those pages
directly, without the protection of the sandbox
attribute.
When an iframe
element with a sandbox
attribute has its nested browsing context created (before the initial about:blank
Document
is created), and when an iframe
element’s sandbox
attribute is set or changed while it
has a nested browsing context, the user agent must parse the sandboxing directive using the attribute’s value as the input, the iframe
element’s nested browsing context’s iframe
sandboxing flag set as the output, and, if the iframe
has an allowfullscreen
attribute, the allow fullscreen flag.
When an iframe
element’s sandbox
attribute is removed while it has a nested browsing context, the user agent must
empty the iframe
element’s nested browsing context’s iframe
sandboxing flag set as the output.
<p>We’re not scared of you! Here is your content, unedited:</p> <iframe title="Example iframe" sandbox src="https://usercontent.example.net/getusercontent.cgi?id=12193"></iframe>
It is important to use a separate domain so that if the attacker convinces the user to visit that page directly, the page doesn’t run in the context of the site’s origin, which would make the user vulnerable to any attack found in the page.
<iframe title="Maps" sandbox="allow-same-origin allow-forms allow-scripts" src="https://maps.example.com/embedded.html"></iframe>
<iframe title="Example iframe" sandbox="allow-same-origin allow-forms" src=B></iframe>
Suppose that file B contained an iframe also:
<iframe title="Example iframe" sandbox="allow-scripts" src=C></iframe>
Further, suppose that file C contained a link:
<a href=D>Link</a>
For this example, suppose all the files were served as text/html
.
Page C in this scenario has all the sandboxing flags set. Scripts are disabled, because the iframe
in A has scripts disabled, and this overrides the allow-scripts
keyword set on the iframe
in B. Forms are also disabled, because the inner iframe
(in B)
does not have the allow-forms
keyword
set.
Suppose now that a script in A removes all the sandbox
attributes in A and B.
This would change nothing immediately. If the user clicked the link in C, loading page D into the iframe
in B, page D would now act as if the iframe
in B had the allow-same-origin
and allow-forms
keywords set, because that was the
state of the nested browsing context in the iframe
in A when page B was
loaded.
Generally speaking, dynamically removing or changing the sandbox
attribute is ill-advised, because it can make it quite
hard to reason about what will be allowed and what will not.
The allowfullscreen
attribute is a boolean attribute. When specified, it indicates that Document
objects in
the iframe
element’s browsing context are to be allowed to use requestFullscreen()
(if it’s not blocked for other
reasons, e.g., there is another ancestor iframe
without this attribute set).
iframe
is used to embed a player from a video site. The allowfullscreen
attribute is needed to enable the
player to show its video fullscreen.
<article> <header> <p><img src="/usericons/1627591962735"> <b>Fred Flintstone</b></p> <p><a href="/posts/3095182851" rel=bookmark>12:44</a> — <a href="#acl-3095182851">Private Post</a></p> </header> <main> <p>Check out my new ride!</p> <iframe title="Video" src="https://video.example.com/embed?id=92469812" allowfullscreen></iframe> </main> </article>
The iframe
element supports dimension attributes for cases where the
embedded content has specific dimensions (e.g., ad units have well-defined dimensions).
An iframe
element never has fallback content, as it will always
create a nested browsing context, regardless of whether the specified initial
contents are successfully used.
Descendants of iframe
elements represent nothing. (In legacy user agents that do
not support iframe
elements, the contents would be parsed as markup that could act as
fallback content.)
When used in HTML documents, the allowed content model
of iframe
elements is text, except that invoking the HTML fragment parsing
algorithm with the iframe
element as the context element and the text contents as
the input must result in a list of nodes that are all phrasing content,
with no parse errors having occurred, with no script
elements being anywhere in the list or as descendants of elements in the list, and with all the
elements in the list (including their descendants) being themselves conforming.
The iframe
element must be empty in XML documents.
The HTML parser treats markup inside iframe
elements as
text.
The IDL attributes src
, srcdoc
, name
, and sandbox
must reflect the respective
content attributes of the same name.
The supported tokens for sandbox
's DOMTokenList
are the
allowed values defined in the sandbox
attribute and supported by the user agent.
The allowFullscreen
IDL attribute
must reflect the allowfullscreen
content attribute.
The contentDocument
IDL attribute must
return the Document
object of the active document of the iframe
element’s nested browsing context, if any and if its origin is the same origin-domain as the origin specified by the incumbent settings object, or null otherwise.
The contentWindow
IDL attribute must
return the WindowProxy
object of the iframe
element’s nested browsing context, if any, or null otherwise.
iframe
to include advertising from an
advertising broker:
<iframe title="Advert" src="https://ads.example.com/?customerid=923513721&format=banner" width="468" height="60"></iframe>
4.7.7. The embed
element
- Categories:
- Flow content.
- Phrasing content.
- Embedded content.
- Interactive content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where embedded content is expected.
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag
- Content attributes:
- Global attributes
src
- Address of the resourcetype
- Type of embedded resourcewidth
- Horizontal dimensionheight
- Vertical dimension- Any other attribute that has no namespace (see prose).
- Allowed ARIA role attribute values:
application
,document
orimg
orpresentation
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLEmbedElement : HTMLElement { attribute DOMString src; attribute DOMString type; attribute DOMString width; attribute DOMString height; legacycaller any (any... arguments); };
Depending on the type of content instantiated by theembed
element, the node may also support other interfaces.
The embed
element provides an integration point for an external (typically
non-HTML) application or interactive content.
The src
attribute gives the address of the
resource being embedded. The attribute, if present, must contain a valid non-empty URL
potentially surrounded by spaces.
The type
attribute, if present, gives the MIME type by which the plugin to instantiate is selected. The value must be a valid mime type. If both the type
attribute and
the src
attribute are present, then the type
attribute must specify the same type as the explicit Content-Type metadata of the resource given by the src
attribute.
While any of the following conditions are occurring, any plugin instantiated for
the element must be removed, and the embed
element represents nothing:
- The element has neither a
src
attribute nor atype
attribute. - The element has a media element ancestor.
- The element has an ancestor
object
element that is not showing its fallback content.
An embed
element is said to be potentially
active when the following conditions are all met simultaneously:
- The element is in a
Document
or was in aDocument
the last time the event loop reached step 1. - The element’s node document is fully active.
- The element has either a
src
attribute set or atype
attribute set (or both). - The element’s
src
attribute is either absent or its value is not the empty string. - The element is not a descendant of a media element.
- The element is not a descendant of an
object
element that is not showing its fallback content. - The element is being rendered, or was being rendered the last time the event loop reached step 1.
Whenever an embed
element that was not potentially active becomes potentially active, and whenever a potentially active embed
element that is
remaining potentially active and has its src
attribute set, changed, or removed or its type
attribute set, changed, or removed, the user agent must queue a task using the embed task source to run the embed
element setup steps.
The embed
element setup steps are as follows:
- If another task has since been queued to run the
embed
element setup steps for this element, then abort these steps. -
- If the element has a
src
attribute set -
The user agent must parse the value of the element’s
src
attribute, relative to the element. If that is successful, the user agent should run these steps:- Let request be a new request whose URL is the resulting URL string, client is the element’s node
document’s
Window
object’s environment settings object, destination is "unknown
", omit-Origin
-header flag is set if the element doesn’t have a browsing context scope origin, credentials mode is "include
", and whose use-URL-credentials flag is set. - Fetch request.
The task that is queued by the networking task source once the resource has been fetched must run the following steps:
- If another task has since been queued to run the
embed
element setup steps for this element, then abort these steps. -
Determine the type of the content being embedded, as follows (stopping at the first substep that determines the type):
- If the element has a
type
attribute, and that attribute’s value is a type that a plugin supports, then the value of thetype
attribute is the content’s type. -
Otherwise, if applying the URL parser algorithm to the URL of the specified resource (after any redirects) results in a URL record whose path component matches a pattern that a plugin supports, then the content’s type is the type that the plugin can handle.
For example, a plugin might say that it can handle resources with path components that end with the four character string "
.swf
". - Otherwise, if the specified resource has explicit Content-Type metadata, then that is the content’s type.
- Otherwise, the content has no type and there can be no appropriate plugin for it.
- If the element has a
-
If the previous step determined that the content’s type is
image/svg+xml
, then run the following substeps:- If the
embed
element is not associated with a nested browsing context, associate the element with a newly created nested browsing context, and, if the element has aname
attribute, set the browsing context name of the element’s nested browsing context to the value of this attribute. - Navigate the nested browsing context to
the fetched resource, with replacement enabled, and with the
embed
element’s node document’s browsing context as the source browsing context. (Thesrc
attribute of theembed
element doesn’t get updated if the browsing context gets further navigated to other locations.) - The
embed
element now represents its associated nested browsing context.
- If the
-
Otherwise, find and instantiate an appropriate plugin based on the content’s type, and hand that plugin the content of the resource, replacing any previously instantiated plugin for the element. The
embed
element now represents this plugin instance. - Once the resource or plugin has completely loaded, queue a task to fire a simple event named
load
at the element.
Whether the resource is fetched successfully or not (e.g., whether the response status was an ok status) must be ignored when determining the content’s type and when handing the resource to the plugin.
This allows servers to return data for plugins even with error responses (e.g., HTTP 500 Internal Server Error codes can still contain plugin data).
Fetching the resource must delay the load event of the element’s node document.
- Let request be a new request whose URL is the resulting URL string, client is the element’s node
document’s
- If the element has no
src
attribute set -
The user agent should find and instantiate an appropriate plugin based on the value of the
type
attribute. Theembed
element now represents this plugin instance.Once the plugin is completely loaded, queue a task to fire a simple event named
load
at the element.
- If the element has a
The embed
element has no fallback content. If the user agent can’t
find a suitable plugin when attempting to find and instantiate one for the algorithm above, then
the user agent must use a default plugin. This default could be as simple as saying "Unsupported
Format".
Whenever an embed
element that was potentially
active stops being potentially active, any plugin that had been instantiated for that element must be unloaded.
When a plugin is to be instantiated but it cannot be secured and the sandboxed plugins browsing context
flag is set on the embed
element’s node document’s active
sandboxing flag set, then the user agent must not instantiate the plugin, and
must instead render the embed
element in a manner that conveys that the plugin was disabled. The user agent may offer the user the option to override the
sandbox and instantiate the plugin anyway; if the user invokes such an option, the
user agent must act as if the conditions above did not apply for the purposes of this element.
Plugins that cannot be secured are disabled in sandboxed browsing contexts because they might not honor the restrictions imposed by the sandbox (e.g., they might allow scripting even when scripting in the sandbox is disabled). User agents should convey the danger of overriding the sandbox to the user if an option to do so is provided.
When an embed
element represents a nested browsing context: if the embed
element’s nested browsing context’s active document is not ready for post-load tasks, and when anything is delaying the load event of the embed
element’s browsing context’s active document, and when the embed
element’s browsing context is in the delaying load
events mode, the embed
must delay the load event of its
document.
The task source for the tasks mentioned in this section is the DOM manipulation task source.
Any namespace-less attribute other than name
, align
, hspace
, and vspace
may be
specified on the embed
element, so long as its name is XML-compatible and contains no uppercase ASCII letters. These attributes are then passed as
parameters to the plugin.
All attributes in HTML documents get lowercased automatically, so the restriction on uppercase letters doesn’t affect such documents.
The four exceptions are to exclude legacy attributes that have side-effects beyond just sending parameters to the plugin.
The user agent should pass the names and values of all the attributes of the embed
element that have no namespace to the plugin used, when one is instantiated.
The HTMLEmbedElement
object representing the element must expose the scriptable
interface of the plugin instantiated for the embed
element, if any. At a
minimum, this interface must implement the legacy caller
operation. (It is suggested that the default behavior of this legacy caller operation, e.g.,
the behavior of the default plugin’s legacy caller operation, be to throw a NotSupportedError
exception.)
The embed
element supports dimension attributes.
The IDL attributes src
and type
each must reflect the respective
content attributes of the same name.
<embed src="catgame.swf">
If the user does not have the plugin (for example if the plugin vendor doesn’t support the user’s platform), then the user will be unable to use the resource.
To pass the plugin a parameter "quality" with the value "high", an attribute can be specified:
<embed src="catgame.swf" quality="high">
This would be equivalent to the following, when using an object
element
instead:
<object data="catgame.swf"> <param name="quality" value="high"> </object>
4.7.8. The object
element
- Categories:
- Flow content.
- Phrasing content.
- Embedded content.
- listed, submittable, and reassociateable form-associated element.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where embedded content is expected.
- Content model:
- Zero or more
param
elements, then, transparent. - Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
data
- Address of the resourcetype
- Type of embedded resourcetypemustmatch
- Whether thetype
attribute and the Content-Type value need to match for the resource to be usedname
- Name of nested browsing contextform
- Associates the control with aform
elementwidth
- Horizontal dimensionheight
- Vertical dimension - Allowed ARIA role attribute values:
application
,document
orimg
orpresentation
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLObjectElement : HTMLElement { attribute DOMString data; attribute DOMString type; attribute boolean typeMustMatch; attribute DOMString name; readonly attribute HTMLFormElement? form; attribute DOMString width; attribute DOMString height; readonly attribute Document? contentDocument; readonly attribute WindowProxy? contentWindow; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); legacycaller any (any... arguments); };
Depending on the type of content instantiated by theobject
element, the node also supports other interfaces.
The object
element can represent an external resource, which, depending on the
type of the resource, will either be treated as an image, as a nested browsing context, or as an external resource to be processed by a plugin.
The data
attribute, if present, specifies the
address of the resource. If present, the attribute must be a valid non-empty URL potentially
surrounded by spaces.
Authors who reference resources from other origins that they do not trust are urged to use the typemustmatch
attribute defined below. Without that
attribute, it is possible in certain cases for an attacker on the remote host to use the plugin
mechanism to run arbitrary scripts, even if the author has used features such as the Flash
"allowScriptAccess" parameter.
The type
attribute, if present, specifies the
type of the resource. If present, the attribute must be a valid mime type.
At least one of either the data
attribute or the type
attribute must be present.
The typeMustMatch
attribute is a boolean attribute whose presence indicates that the resource specified by the data
attribute is only to be used if the value of the type
attribute and the Content-Type of the
aforementioned resource match.
The typemustmatch
attribute must not be
specified unless both the data
attribute and the type
attribute are present.
The name
attribute, if present, must be a valid browsing context name. The given value is used to name the nested browsing context, if applicable.
Whenever one of the following conditions occur:
- the element is created,
- the element is popped off the stack of open elements of an HTML parser or XML parser,
- the element is not on the stack of open elements of an HTML parser or XML parser, and it is either inserted into a document or removed from a document,
- the element’s node document changes whether it is fully active,
- one of the element’s ancestor
object
elements changes to or from showing its fallback content, - the element’s
classid
attribute is set, changed, or removed, - the element’s
classid
attribute is not present, and itsdata
attribute is set, changed, or removed, - neither the element’s
classid
attribute nor itsdata
attribute are present, and itstype
attribute is set, changed, or removed, - the element changes from being rendered to not being rendered, or vice versa,
...the user agent must queue a task to run the following steps to (re)determine
what the object
element represents. This task being queued or actively running must delay the load
event of the element’s node document.
-
If the user has indicated a preference that this
object
element’s fallback content be shown instead of the element’s usual behavior, then jump to the step below labeled fallback.For example, a user could ask for the element’s fallback content to be shown because that content uses a format that the user finds more accessible.
-
If the element has an ancestor media element, or has an ancestor
object
element that is not showing its fallback content, or if the element is not in aDocument
with a browsing context, or if the element’s node document is not fully active, or if the element is still in the stack of open elements of an HTML parser or XML parser, or if the element is not being rendered, then jump to the step below labeled fallback. -
If the
classid
attribute is present, and has a value that isn’t the empty string, then: if the user agent can find a plugin suitable according to the value of theclassid
attribute, and either plugins aren’t being sandboxed or that plugin can be secured, then that plugin should be used, and the value of thedata
attribute, if any, should be passed to the plugin. If no suitable plugin can be found, or if the plugin reports an error, jump to the step below labeled fallback. -
If the
data
attribute is present and its value is not the empty string, then:- If the
type
attribute is present and its value is not a type that the user agent supports, and is not a type that the user agent can find a plugin for, then the user agent may jump to the step below labeled fallback without fetching the content to examine its real type. - Parse the URL specified by the
data
attribute, relative to the element. - If that failed, fire a simple event named
error
at the element, then jump to the step below labeled fallback. - Let request be a new request whose URL is the resulting URL string, client is the element’s node
document’s
Window
object’s environment settings object, destination is "unknown
", omit-Origin
-header flag is set if the element doesn’t have a browsing context scope origin, credentials mode is "include
", and whose use-URL-credentials flag is set. -
Fetch request.
Fetching the resource must delay the load event of the element’s node document until the task that is queued by the networking task source once the resource has been fetched (defined next) has been run.
- If the resource is not yet available (e.g., because the resource was not available in the cache, so that loading the resource required making a request over the network), then jump to the step below labeled fallback. The task that is queued by the networking task source once the resource is available must restart this algorithm from this step. Resources can load incrementally; user agents may opt to consider a resource "available" whenever enough data has been obtained to begin processing the resource.
- If the load failed (e.g., there was an HTTP 404 error, there was a DNS error), fire
a simple event named
error
at the element, then jump to the step below labeled fallback. -
Determine the resource type, as follows:
-
Let the resource type be unknown.
-
If the
object
element has atype
attribute and atypemustmatch
attribute, and the resource has associated Content-Type metadata, and the type specified in the resource’s Content-Type metadata is an ASCII case-insensitive match for the value of the element’stype
attribute, then let resource type be that type and jump to the step below labeled handler. -
If the
object
element has atypemustmatch
attribute, jump to the step below labeled handler. -
If the user agent is configured to strictly obey Content-Type headers for this resource, and the resource has associated Content-Type metadata, then let the resource type be the type specified in the resource’s Content-Type metadata, and jump to the step below labeled handler.
This can introduce a vulnerability, wherein a site is trying to embed a resource that uses a particular plugin, but the remote site overrides that and instead furnishes the user agent with a resource that triggers a different plugin with different security characteristics.
-
If there is a
type
attribute present on theobject
element, and that attribute’s value is not a type that the user agent supports, but it is a type that a plugin supports, then let the resource type be the type specified in thattype
attribute, and jump to the step below labeled handler. -
Run the appropriate set of steps from the following list:
- If the resource has associated Content-Type metadata
-
-
Let binary be false.
-
If the type specified in the resource’s Content-Type metadata is "
text/plain
", and the result of applying the rules for distinguishing if a resource is text or binary to the resource is that the resource is nottext/plain
, then set binary to true. -
If the type specified in the resource’s Content-Type metadata is "
application/octet-stream
", then set binary to true. -
If binary is false, then let the resource type be the type specified in the resource’s Content-Type metadata, and jump to the step below labeled handler.
-
If there is a
type
attribute present on theobject
element, and its value is notapplication/octet-stream
, then run the following steps:-
If the attribute’s value is a type that a plugin supports, or the
attribute’s value is a type that starts with "image/
" that is not also an XML MIME type, then let the resource type be the type specified in thattype
attribute. -
Jump to the step below labeled handler.
-
-
- Otherwise, if the resource does not have associated Content-Type metadata
-
-
If there is a
type
attribute present on theobject
element, then let the tentative type be the type specified in thattype
attribute.Otherwise, let tentative type be the computed type of the resource.
-
If tentative type is not
application/octet-stream
, then let resource type be tentative type and jump to the step below labeled handler.
-
-
If applying the URL parser algorithm to the URL of the specified resource (after any redirects) results in a URL record whose path component matches a pattern that a plugin supports, then let resource type be the type that the plugin can handle.
For example, a plugin might say that it can handle resources with path components that end with the four character string "
.swf
".
It is possible for this step to finish, or for one of the substeps above to jump straight to the next step, with resource type still being unknown. In both cases, the next step will trigger fallback.
-
-
Handler: Handle the content as given by the first of the following cases that
matches:
- If the resource type is not a type that the user agent supports, but it is a type that a plugin supports
-
If plugins are being sandboxed and the plugin that supports resource type cannot be secured, jump to the step below labeled fallback.
Otherwise, the user agent should use the plugin that supports resource type and pass the content of the resource to that plugin. If the plugin reports an error, then jump to the step below labeled fallback.
- If the resource type is an XML MIME type, or if the resource type does not start with "
image/
" -
The
object
element must be associated with a newly created nested browsing context, if it does not already have one.If the URL of the given resource is not
about:blank
, the element’s nested browsing context must then be navigated to that resource, with replacement enabled, and with theobject
element’s node document’s browsing context as the source browsing context. (Thedata
attribute of theobject
element doesn’t get updated if the browsing context gets further navigated to other locations.)If the URL of the given resource is
about:blank
, then, instead, the user agent must queue a task to fire a simple event namedload
at theobject
element. Noload
event is fired at theabout:blank
document itself.The
object
element represents the nested browsing context.If the
name
attribute is present, the browsing context name must be set to the value of this attribute; otherwise, the browsing context name must be set to the empty string. - If the resource type starts with "
image/
", and support for images has not been disabled -
Apply the image sniffing rules to determine the type of the image.
The
object
element represents the specified image. The image is not a nested browsing context.If the image cannot be rendered, e.g., because it is malformed or in an unsupported format, jump to the step below labeled fallback.
- Otherwise
-
The given resource type is not supported. Jump to the step below labeled fallback.
If the previous step ended with the resource type being unknown, this is the case that is triggered.
- The element’s contents are not part of what the
object
element represents. -
Abort these steps. Once the resource is completely loaded, queue a task to fire a simple event named
load
at the element.
- If the
- If the
data
attribute is absent but thetype
attribute is present, and the user agent can find a plugin suitable according to the value of thetype
attribute, and either plugins aren’t being sandboxed or the plugin can be secured, then that plugin should be used. If these conditions cannot be met, or if the plugin reports an error, jump to the step below labeled fallback. Otherwise abort these steps; once the plugin is completely loaded, queue a task to fire a simple event namedload
at the element. - Fallback: The
object
element represents the element’s children, ignoring any leadingparam
element children. This is the element’s fallback content. If the element has an instantiated plugin, then unload it.
When the algorithm above instantiates a plugin, the user agent
should pass to the plugin used the names and values of all the attributes on the
element, in the order they were added to the element, with the attributes added by the parser
being ordered in source order, followed by a parameter named "PARAM" whose value is null, followed
by all the names and values of parameters given by param
elements that are children of the object
element, in tree
order. If the plugin supports a scriptable interface, the HTMLObjectElement
object representing the element should expose that interface. The object
element represents the plugin. The plugin is not a nested browsing context.
Plugins are considered sandboxed for the purpose of an object
element if the sandboxed plugins browsing context flag is set on
the object
element’s node document’s active sandboxing flag
set.
Due to the algorithm above, the contents of object
elements act as fallback
content, used only when referenced resources can’t be shown (e.g., because it returned a 404
error). This allows multiple object
elements to be nested inside each other,
targeting multiple user agents with different capabilities, with the user agent picking the first
one it supports.
When an object
element represents a nested browsing context: if the object
element’s nested browsing context’s active document is not ready for post-load tasks, and when anything is delaying the load event of the object
element’s browsing context’s active document, and when the object
element’s browsing context is in the delaying load
events mode, the object
must delay the load event of its
document.
The task source for the tasks mentioned in this section is the DOM manipulation task source.
Whenever the name
attribute is set, if the object
element has a nested browsing context, its name must be changed to the new value. If the attribute is removed, if the object
element has a browsing context, the browsing context name must be set to the empty string.
The form
attribute is used to explicitly associate the object
element with its form owner.
Constraint validation: object
elements are always barred
from constraint validation.
The object
element supports dimension attributes.
The IDL attributes data
, type
and name
each must reflect the respective
content attributes of the same name. The typeMustMatch
IDL attribute must reflect the typemustmatch
content
attribute.
The contentDocument
IDL attribute must return the Document
object of the active document of the object
element’s nested browsing context, if any and if
its origin is the same origin-domain as the origin specified by the incumbent settings object, or null otherwise.
The contentWindow
IDL attribute must
return the WindowProxy
object of the object
element’s nested browsing context, if it has one; otherwise, it must return null.
The willValidate
, validity
, and validationMessage
attributes, and the checkValidity()
, reportValidity()
, and setCustomValidity()
methods, are part of the constraint validation API. The form
IDL attribute
is part of the element’s forms API.
All object
elements have a legacy caller
operation. If the object
element has an instantiated plugin that
supports a scriptable interface that defines a legacy caller operation, then that must be the
behavior of the object’s legacy caller operation. Otherwise, the object’s legacy caller operation
must be to throw a NotSupportedError
exception.
object
element. (Generally speaking, it is better to avoid using applets like these and instead use
native JavaScript and HTML to provide the functionality, since that way the application will work
on all Web browsers without requiring a third-party plugin. Many devices, especially embedded
devices, do not support third-party technologies like Java.)
<figure> <object type="application/x-java-applet"> <param name="code" value="MyJavaClass"> <p>You do not have Java available, or it is disabled.</p> </object> <figcaption>My Java Clock</figcaption> </figure>
object
element.
<figure> <object data="clock.html"></object> <figcaption>My HTML Clock</figcaption> </figure>
video
element to show the video for those using user agents that support video
, and finally providing a link to the video for those who have neither Flash
nor a video
-capable browser.
<p>Look at my video: <object type="application/x-shockwave-flash"> <param name=movie value="https://video.example.com/library/watch.swf"> <param name=allowfullscreen value=true> <param name=flashvars value="https://video.example.com/vids/315981"> <video controls src="https://video.example.com/vids/315981"> <a href="https://video.example.com/vids/315981">View video</a>. </video> </object> </p>
4.7.9. The param
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of an
object
element, before any flow content. - Content model:
- Nothing.
- Tag omission in text/html:
- No end tag
- Content attributes:
- Global attributes
name
- Name of parametervalue
- Value of parameter - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLParamElement : HTMLElement { attribute DOMString name; attribute DOMString value; };
The param
element defines parameters for plugins invoked by object
elements. It does not represent anything on its own.
The name
attribute gives the name of the
parameter.
The value
attribute gives the value of the
parameter.
Both attributes must be present. They may have any value.
If both attributes are present, and if the parent element of the param
is an object
element, then the element defines a parameter with the given name-value pair.
If either the name or value of a parameter defined
by a param
element that is the child of an object
element that represents an instantiated plugin changes, and if that plugin is communicating with the user agent using an API that features the ability to
update the plugin when the name or value of a parameter so changes, then the user agent must
appropriately exercise that ability to notify the plugin of the change.
The IDL attributes name
and value
must both reflect the respective
content attributes of the same name.
param
element can be used to pass a parameter
to a plugin, in this case the O3D plugin.
<!DOCTYPE HTML> <html lang="en"> <head> <title>O3D Utah Teapot</title> </head> <body> <p> <object type="application/vnd.o3d.auto"> <param name="o3d_features" value="FloatingPointTextures"> <img src="o3d-teapot.png" title="3D Utah Teapot illustration rendered using O3D." alt="When O3D renders the Utah Teapot, it appears as a squat teapot with a shiny metallic finish on which the surroundings are reflected, with a faint shadow caused by the lighting."> <p>To see the teapot actually rendered by O3D on your computer, please download and install the <a href="https://code.google.com/apis/o3d/docs/gettingstarted.html#install">O3D plugin</a>.</p> </object> <script src="o3d-teapot.js"></script> </p> </body> </html>
4.7.10. The video
element
- Categories:
- Flow content.
- Phrasing content.
- Embedded content.
- If the element has a
controls
attribute: interactive content.- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where embedded content is expected.
- Content model:
- If the element has a
src
attribute: zero or moretrack
elements, then transparent, but with no media element descendants.- If the element does not have a
src
attribute: zero or moresource
elements, then zero or moretrack
elements, then transparent, but with no media element descendants. - If the element does not have a
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
src
- Address of the resourcecrossorigin
- How the element handles crossorigin requestsposter
- Poster frame to show prior to video playbackpreload
- Hints how much buffering the media resource will likely needautoplay
- Hint that the media resource can be started automatically when the page is loadedloop
- Whether to loop the media resourcemuted
- Whether to mute the media resource by defaultcontrols
- Show user agent controlswidth
- Horizontal dimensionheight
- Vertical dimension - Allowed ARIA role attribute values:
application
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLVideoElement : HTMLMediaElement { attribute unsigned long width; attribute unsigned long height; readonly attribute unsigned long videoWidth; readonly attribute unsigned long videoHeight; attribute DOMString poster; };
A video
element is used for playing videos or movies, and audio files with
captions.
Content may be provided inside the video
element. User agents
should not show this content to the user; it is intended for older Web browsers which do
not support video
, so that legacy video plugins can be tried, or to show text to the
users of these older browsers informing them of how to access the video contents.
In particular, this content is not intended to address accessibility concerns. To
make video content accessible to the partially sighted, the blind, the hard-of-hearing, the deaf,
and those with other physical or cognitive disabilities, a variety of features are available.
Captions can be provided, either embedded in the video stream or as external files using the track
element. Sign-language tracks can be provided, again either embedded in the
video stream. Audio descriptions can be provided, either as a separate track embedded in the video
stream, or in text form using a WebVTT file referenced using the track
element and
synthesized into speech by the user agent. WebVTT can also be used to provide chapter titles. For
users who would rather not use a media element at all, transcripts or other textual alternatives
can be provided by simply linking to them in the prose near the video
element. [WEBVTT]
The video
element is a media element whose media data is
ostensibly video data, possibly with associated audio data.
The src
, preload
, autoplay
, loop
, muted
, and controls
attributes are the attributes common to all media elements.
The poster
content attribute gives the address of an
image file that the user agent can show while no video data is available. The attribute, if
present, must contain a valid non-empty URL potentially surrounded by spaces.
If the specified resource is to be used, then, when the element is created or when the poster
attribute is set, changed, or removed, the user agent must
run the following steps to determine the element’s poster frame (regardless of the
value of the element’s show poster flag):
- If there is an existing instance of this algorithm running for this
video
element, abort that instance of this algorithm without changing the poster frame. - If the
poster
attribute’s value is the empty string or if the attribute is absent, then there is no poster frame; abort these steps. - Parse the
poster
attribute’s value relative to the element. If this fails, then there is no poster frame; abort these steps. - Let request be a new request whose URL is the resulting URL string, client is the element’s node document’s
Window
object’s environment settings object, type is "image
", destination is "subresource
", credentials mode is "include
", and whose use-URL-credentials flag is set. - Fetch request. This must delay the load event of the element’s node document.
- If an image is thus obtained, the poster frame is that image. Otherwise, there is no poster frame.
The image given by the poster
attribute,
the poster frame, is intended to be a representative frame of the
video (typically one of the first non-blank frames) that gives the user an idea of what the video
is like.
A video
element represents what is given for the first matching condition in the
list below:
- When no video data is available (the element’s
readyState
attribute is eitherHAVE_NOTHING
, orHAVE_METADATA
but no video data has yet been obtained at all, or the element’sreadyState
attribute is any subsequent value but the media resource does not have a video channel) - The
video
element represents its poster frame, if any, or else transparent black with no intrinsic dimensions. - When the
video
element is paused, the current playback position is the first frame of video, and the element’s show poster flag is set - The
video
element represents its poster frame, if any, or else the first frame of the video. - When the
video
element is paused, and the frame of video corresponding to the current playback position is not available (e.g., because the video is seeking or buffering)- When the
video
element is neither potentially playing nor paused (e.g., when seeking or stalled) - When the
- The
video
element represents the last frame of the video to have been rendered. - When the
video
element is paused - The
video
element represents the frame of video corresponding to the current playback position. - Otherwise (the
video
element has a video channel and is potentially playing) - The
video
element represents the frame of video at the continuously increasing "current" position. When the current playback position changes such that the last frame rendered is no longer the frame corresponding to the current playback position in the video, the new frame must be rendered.
Frames of video must be obtained from the video track that was selected when the event loop last reached step 1.
Which frame in a video stream corresponds to a particular playback position is defined by the video stream’s format.
The video
element also represents any text track cues whose text track cue active flag is set and whose text track is in the showing mode, and any
audio from the media resource, at the current playback position.
Any audio associated with the media resource must, if played, be played synchronized with the current playback position, at the element’s effective media volume. The user agent must play the audio from audio tracks that were enabled when the event loop last reached step 1.
In addition to the above, the user agent may provide messages to the user (such as "buffering", "no video loaded", "error", or more detailed information) by overlaying text or icons on the video or other areas of the element’s playback area, or in another appropriate manner.
User agents that cannot render the video may instead make the element represent a link to an external video playback utility or to the video data itself.
When a video
element’s media resource has a video channel, the
element provides a paint source whose width is the media resource’s intrinsic width, whose height is the media resource’s intrinsic height, and whose appearance is
the frame of video corresponding to the current playback position, if that is available, or else
(e.g., when the video is seeking or buffering) its previous appearance, if any, or else (e.g.,
because the video is still loading the first frame) blackness.
- video .
videoWidth
- video .
videoHeight
- video .
-
These attributes return the intrinsic dimensions of the video, or zero if the dimensions are not known.
The intrinsic width and intrinsic height of the media resource are the dimensions of the resource in CSS pixels after taking into account the resource’s dimensions, aspect ratio, clean aperture, resolution, and so forth, as defined for the format used by the resource. If an anamorphic format does not define how to apply the aspect ratio to the video data’s dimensions to obtain the "correct" dimensions, then the user agent must apply the ratio by increasing one dimension and leaving the other unchanged.
The videoWidth
IDL attribute must return
the intrinsic width of the video in CSS pixels.
The videoHeight
IDL attribute must return
the intrinsic height of the video in CSS
pixels. If the element’s readyState
attribute is HAVE_NOTHING
, then the attributes must return 0.
Whenever the intrinsic width or intrinsic height of the video changes
(including, for example, because the selected video
track was changed), if the element’s readyState
attribute is not HAVE_NOTHING
, the user agent must queue a task to fire a simple event named resize
at the media element.
The video
element supports dimension attributes.
In the absence of style rules to the contrary, video content should be rendered inside the element’s playback area such that the video content is shown centered in the playback area at the largest possible size that fits completely within it, with the video content’s aspect ratio being preserved. Thus, if the aspect ratio of the playback area does not match the aspect ratio of the video, the video will be shown letterboxed or pillarboxed. Areas of the element’s playback area that do not contain the video represent nothing.
In user agents that implement CSS, the above requirement can be implemented by using the style rule suggested in §10 Rendering.
The intrinsic width of a video
element’s playback area is the intrinsic width of the poster frame, if that is available and the
element currently represents its poster frame; otherwise, it is the intrinsic width of the video resource, if that is
available; otherwise the intrinsic width is missing.
The intrinsic height of a video
element’s playback area is the intrinsic height of the poster frame, if that is available and the
element currently represents its poster frame; otherwise it is the intrinsic height of the video resource, if that is
available; otherwise the intrinsic height is missing.
The default object size is a width of 300 CSS pixels and a height of 150 CSS pixels. [CSS3-IMAGES]
User agents should provide controls to enable or disable the display of closed captions, audio description tracks, and other additional data associated with the video stream, though such features should, again, not interfere with the page’s normal rendering.
User agents may allow users to view the video content in manners more suitable to the user
(e.g., fullscreen or in an independent resizable window). As for the other user interface
features, controls to enable this should not interfere with the page’s normal rendering unless the
user agent is exposing a user interface.
In such an independent context, however, user agents may make full user interfaces visible even
if the controls
attribute is absent.
User agents may allow video playback to affect system features that could interfere with the user’s experience; for example, user agents could disable screensavers while video playback is in progress.
The poster
IDL attribute must reflect the poster
content attribute.
<script> function failed(e) { // video playback failed - show a message saying why switch (e.target.error.code) { case e.target.error.MEDIA_ERR_ABORTED: alert('You aborted the video playback.'); break; case e.target.error.MEDIA_ERR_NETWORK: alert('A network error caused the video download to fail part-way.'); break; case e.target.error.MEDIA_ERR_DECODE: alert('The video playback was aborted due to a corruption problem or because the video used features your browser did not support.'); break; case e.target.error.MEDIA_ERR_SRC_NOT_SUPPORTED: alert('The video could not be loaded, either because the server or network failed or because the format is not supported.'); break; default: alert('An unknown error occurred.'); break; } } </script> <p><video src="tgif.vid" autoplay controls onerror="failed(event)"></video></p> <p><a href="tgif.vid">Download the video file</a>.</p>
4.7.11. The audio
element
- Categories:
- Flow content.
- Phrasing content.
- Embedded content.
- If the element has a
controls
attribute: Interactive content.- If the element has a
controls
attribute: Palpable content. - Phrasing content.
- Contexts in which this element can be used:
- Where embedded content is expected.
- Content model:
- If the element has a
src
attribute: zero or moretrack
elements, then transparent, but with no media element descendants.- If the element does not have a
src
attribute: zero or moresource
elements, then zero or moretrack
elements, then transparent, but with no media element descendants. - If the element does not have a
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
src
- Address of the resourcecrossorigin
- How the element handles crossorigin requestspreload
- Hints how much buffering the media resource will likely needautoplay
- Hint that the media resource can be started automatically when the page is loadedloop
- Whether to loop the media resourcemuted
- Whether to mute the media resource by defaultcontrols
- Show user agent controls - Allowed ARIA role attribute values:
application
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
[NamedConstructor=Audio(optional DOMString src)] interface HTMLAudioElement : HTMLMediaElement {};
An audio
element represents a sound or audio stream.
Content may be provided inside the audio
element. User agents
should not show this content to the user; it is intended for older Web browsers which do
not support audio
, so that legacy audio plugins can be tried, or to show text to the
users of these older browsers informing them of how to access the audio contents.
In particular, this content is not intended to address accessibility concerns. To
make audio content accessible to the deaf or to those with other physical or cognitive
disabilities, a variety of features are available. If captions or a sign language video are
available, the video
element can be used instead of the audio
element to
play the audio, allowing users to enable the visual alternatives. Chapter titles can be provided
to aid navigation, using the track
element and a WebVTT file. And,
naturally, transcripts or other textual alternatives can be provided by simply linking to them in
the prose near the audio
element. [WEBVTT]
The audio
element is a media element whose media data is
ostensibly audio data.
The src
, preload
, autoplay
, loop
, muted
, and controls
attributes are the attributes common to all media elements.
When an audio
element is potentially playing, it must have its audio
data played synchronized with the current playback position, at the element’s effective media volume. The user agent must play the audio from audio tracks that
were enabled when the event loop last reached step 1.
When an audio
element is not potentially playing, audio must not play
for the element.
- audio = new
Audio
( [ url ] ) -
Returns a new
audio
element, with thesrc
attribute set to the value passed in the argument, if applicable.
A constructor is provided for creating HTMLAudioElement
objects (in addition to
the factory methods from DOM such as createElement()
): Audio(src)
. When invoked as a
constructor, it must return a new HTMLAudioElement
object (a new audio
element). The element must be created with its preload
attribute set to the literal value "auto
". If the src argument is present, the object created must be created with its src
content attribute set to the provided value (this will cause the user agent to invoke the object’s resource selection algorithm before returning).
The element’s node document must be the active document of the browsing context of the Window
object on which the interface object of the invoked
constructor is found.
4.7.12. The source
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a media element, before any flow content or
track
elements. - Content model:
- Nothing.
- Tag omission in text/html:
- No end tag
- Content attributes:
- Global attributes
src
- Address of the resourcetype
- Type of embedded resource - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLSourceElement : HTMLElement { attribute DOMString src; attribute DOMString type; };
The source
element allows authors to specify multiple alternative media resources for media elements. It does not represent anything on its own.
The src
attribute gives the address of the media resource. The value must be a valid non-empty URL potentially surrounded
by spaces. This attribute must be present.
Dynamically modifying a source
element and its attribute when the
element is already inserted in a video
or audio
element will have no
effect. To change what is playing, just use the src
attribute
on the media element directly, possibly making use of the canPlayType()
method to pick from amongst available
resources. Generally, manipulating source
elements manually after the document has
been parsed is an unnecessarily complicated approach.
The type
content attribute gives the type of the media resource, to help the user agent determine if it can play this media
resource before fetching it. If specified, its value must be a valid MIME
type. The codecs
parameter, which certain MIME types define, might be
necessary to specify exactly how the resource is encoded. [RFC6381]
codecs=
MIME
parameter in the type
attribute.
- H.264 Constrained baseline profile video (main and extended video compatible) level 3 and Low-Complexity AAC audio in MP4 container
-
<source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'>
- H.264 Extended profile video (baseline-compatible) level 3 and Low-Complexity AAC audio in MP4 container
-
<source src='video.mp4' type='video/mp4; codecs="avc1.58A01E, mp4a.40.2"'>
- H.264 Main profile video level 3 and Low-Complexity AAC audio in MP4 container
-
<source src='video.mp4' type='video/mp4; codecs="avc1.4D401E, mp4a.40.2"'>
- H.264 "High" profile video (incompatible with main, baseline, or extended profiles) level 3 and Low-Complexity AAC audio in MP4 container
-
<source src='video.mp4' type='video/mp4; codecs="avc1.64001E, mp4a.40.2"'>
- MPEG-4 Visual Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container
-
<source src='video.mp4' type='video/mp4; codecs="mp4v.20.8, mp4a.40.2"'>
- MPEG-4 Advanced Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container
-
<source src='video.mp4' type='video/mp4; codecs="mp4v.20.240, mp4a.40.2"'>
- MPEG-4 Visual Simple Profile Level 0 video and AMR audio in 3GPP container
-
<source src='video.3gp' type='video/3gpp; codecs="mp4v.20.8, samr"'>
- Theora video and Vorbis audio in Ogg container
-
<source src='video.ogv' type='video/ogg; codecs="theora, vorbis"'>
- Theora video and Speex audio in Ogg container
-
<source src='video.ogv' type='video/ogg; codecs="theora, speex"'>
- Vorbis audio alone in Ogg container
-
<source src='audio.ogg' type='audio/ogg; codecs=vorbis'>
- Speex audio alone in Ogg container
-
<source src='audio.spx' type='audio/ogg; codecs=speex'>
- FLAC audio alone in Ogg container
-
<source src='audio.oga' type='audio/ogg; codecs=flac'>
- Dirac video and Vorbis audio in Ogg container
-
<source src='video.ogv' type='video/ogg; codecs="dirac, vorbis"'>
If a source
element is inserted as a child of a media element that
has no src
attribute and whose networkState
has the value NETWORK_EMPTY
, the user agent must invoke the media element’s resource selection
algorithm.
The IDL attributes src
and type
must reflect the respective content
attributes of the same name.
error
event on the last source
element and trigger fallback behavior:
<script> function fallback(video) { // replace <video> with its contents while (video.hasChildNodes()) { if (video.firstChild instanceof HTMLSourceElement) video.removeChild(video.firstChild); else video.parentNode.insertBefore(video.firstChild, video); } video.parentNode.removeChild(video); } </script> <video controls autoplay> <source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'> <source src='video.ogv' type='video/ogg; codecs="theora, vorbis"' onerror="fallback(parentNode)"> ... </video>
4.7.13. The track
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a media element, before any flow content.
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag
- Content attributes:
- Global attributes
kind
- The type of text tracksrc
- Address of the resourcesrclang
- Language of the text tracklabel
- User-visible labeldefault
- Enable the track if no other text track is more suitable - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLTrackElement : HTMLElement { attribute DOMString kind; attribute DOMString src; attribute DOMString srclang; attribute DOMString label; attribute boolean default; const unsigned short NONE = 0; const unsigned short LOADING = 1; const unsigned short LOADED = 2; const unsigned short ERROR = 3; readonly attribute unsigned short readyState; readonly attribute TextTrack track; };
The track
element allows authors to specify explicit external text resources for media elements. It
does not represent anything on its own.
The kind
attribute is an enumerated
attribute. The following table lists the keywords defined for this attribute. The keyword
given in the first cell of each row maps to the state given in the second cell.
Keyword | State | Brief description |
---|---|---|
subtitles
| Subtitles | Transcription or translation of the dialog, suitable for when the sound is available but not understood (e.g., because the user does not understand the language of the media resource’s audio track). Overlaid on the video. |
captions
| Captions | Transcription or translation of the dialog, sound effects, relevant musical cues, and other relevant audio information, suitable for when sound is unavailable or not clearly audible (e.g., because it is muted, drowned-out by ambient noise, or because the user is deaf). Overlaid on the video; labeled as appropriate for the hard-of-hearing. |
descriptions
| Descriptions | Textual descriptions of the video component of the media resource, intended for audio synthesis when the visual component is obscured, unavailable, or not usable (e.g., because the user is interacting with the application without a screen while driving, or because the user is blind). Synthesized as audio. |
chapters
| Chapters | Chapter titles, intended to be used for navigating the media resource. Displayed as an interactive (potentially nested) list in the user agent’s interface. |
metadata
| Metadata | Tracks intended for use from script. Not displayed by the user agent. |
The attribute may be omitted. The missing value default is the subtitles state. The invalid value default is the metadata state.
The src
attribute gives the address of the text
track data. The value must be a valid non-empty URL potentially surrounded by spaces.
This attribute must be present.
If the element has a src
attribute whose value is not the
empty string and whose value, when the attribute was set, could be successfully parsed relative to the element’s node document, then the element’s track URL is the resulting URL string. Otherwise, the element’s track URL is the empty string.
kind
attribute is not in the Metadata state, then the WebVTT file must be
a WebVTT file using cue text. [WEBVTT]
Furthermore, if the element’s track URL identifies a WebVTT resource,
and the element’s kind
attribute is in the chapters state, then the WebVTT file must be
both a WebVTT file using chapter title text and a WebVTT file using only nested
cues. [WEBVTT]
The srclang
attribute gives the language of
the text track data. The value must be a valid BCP 47 language tag. This attribute must be present
if the element’s kind
attribute is in the subtitles state. [BCP47]
If the element has a srclang
attribute whose value is
not the empty string, then the element’s track language is the value of the attribute.
Otherwise, the element has no track language.
The label
attribute gives a user-readable
title for the track. This title is used by user agents when listing subtitle, caption, and audio description tracks in their user interface.
The value of the label
attribute, if the attribute is
present, must not be the empty string. Furthermore, there must not be two track
element children of the same media element whose kind
attributes are in the same state, whose srclang
attributes are both missing or have values that
represent the same language, and whose label
attributes are
again both missing or both have the same value.
If the element has a label
attribute whose value is not
the empty string, then the element’s track label is the value of the attribute.
Otherwise, the element’s track label is an empty string.
The default
attribute is a boolean
attribute, which, if specified, indicates that the track is to be enabled if the user’s
preferences do not indicate that another track would be more appropriate.
Each media element must have no more than one track
element child
whose kind
attribute is in the Subtitles or Captions state and whose default
attribute is specified.
Each media element must have no more than one track
element child
whose kind
attribute is in the Descriptions state and whose default
attribute is specified.
Each media element must have no more than one track
element child
whose kind
attribute is in the Chapters state and whose default
attribute is specified.
There is no limit on the number of track
elements whose kind
attribute is in the Metadata state and whose default
attribute is specified.
- track .
readyState
-
Returns the text track readiness state,
represented by a number from the following list:
- track .
NONE
(0) - The text track not loaded state.
- track .
LOADING
(1) - The text track loading state.
- track .
LOADED
(2) - The text track loaded state.
- track .
ERROR
(3) - The text track failed to load state.
- track .
- track .
track
-
Returns the
TextTrack
object corresponding to the text track of thetrack
element.
The readyState
attribute must return the
numeric value corresponding to the text track readiness state of the track
element’s text track, as defined by the following list:
NONE
(numeric value 0)- The text track not loaded state.
LOADING
(numeric value 1)- The text track loading state.
LOADED
(numeric value 2)- The text track loaded state.
ERROR
(numeric value 3)- The text track failed to load state.
The track
IDL attribute must, on getting,
return the track
element’s text track’s corresponding TextTrack
object.
The src
, srclang
, label
, and default
IDL attributes must reflect the
respective content attributes of the same name. The kind
IDL attribute must reflect the content
attribute of the same name, limited to only known values.
<video src="brave.webm"> <track kind=subtitles src=brave.en.vtt srclang=en label="English"> <track kind=captions src=brave.en.hoh.vtt srclang=en label="English for the Hard of Hearing"> <track kind=subtitles src=brave.fr.vtt srclang=fr lang=fr label="Français"> <track kind=subtitles src=brave.de.vtt srclang=de lang=de label="Deutsch"> </video>
(The lang
attributes on the last two describe the language of
the label
attribute, not the language of the subtitles
themselves. The language of the subtitles is given by the srclang
attribute.)
4.7.14. Media elements
HTMLMediaElement
objects (audio
and video
, in this specification) are simply known as media elements.
enum CanPlayTypeResult { "" /* empty string */, "maybe", "probably" };
typedef (MediaStream or MediaSource or Blob) MediaProvider;
interface HTMLMediaElement : HTMLElement { // error state readonly attribute MediaError? error; // network state attribute DOMString src; attribute MediaProvider? srcObject; readonly attribute DOMString currentSrc; attribute DOMString? crossOrigin; const unsigned short NETWORK_EMPTY = 0; const unsigned short NETWORK_IDLE = 1; const unsigned short NETWORK_LOADING = 2; const unsigned short NETWORK_NO_SOURCE = 3; readonly attribute unsigned short networkState; attribute DOMString preload; readonly attribute TimeRanges buffered; void load(); CanPlayTypeResult canPlayType(DOMString type); // ready state const unsigned short HAVE_NOTHING = 0; const unsigned short HAVE_METADATA = 1; const unsigned short HAVE_CURRENT_DATA = 2; const unsigned short HAVE_FUTURE_DATA = 3; const unsigned short HAVE_ENOUGH_DATA = 4; readonly attribute unsigned short readyState; readonly attribute boolean seeking; // playback state attribute double currentTime; void fastSeek(double time); readonly attribute unrestricted double duration; object getStartDate(); readonly attribute boolean paused; attribute double defaultPlaybackRate; attribute double playbackRate; readonly attribute TimeRanges played; readonly attribute TimeRanges seekable; readonly attribute boolean ended; attribute boolean autoplay; attribute boolean loop; void play(); void pause(); // controls attribute boolean controls; attribute double volume; attribute boolean muted; attribute boolean defaultMuted; // tracks [SameObject] readonly attribute AudioTrackList audioTracks; [SameObject] readonly attribute VideoTrackList videoTracks; [SameObject] readonly attribute TextTrackList textTracks; TextTrack addTextTrack(TextTrackKind kind, optional DOMString label = "", optional DOMString language = ""); };
The media element attributes, src
, crossorigin
, preload
, autoplay
, loop
, muted
, and controls
, apply to all media elements. They are defined in this section.
Media elements are used to present audio data, or video and audio data, to the user. This is referred to as media data in this section, since this section applies equally to media elements for audio or for video.
The term media resource is used to refer to the complete set of media data, e.g., the complete video file, or complete audio file.
A media resource can have multiple audio and video tracks. For the purposes of a media element, the video data of the media resource is only that of the
currently selected track (if any) as given by the element’s videoTracks
attribute when the event loop last
reached step 1, and the audio data of the media resource is the result of mixing all
the currently enabled tracks (if any) given by the element’s audioTracks
attribute when the event loop last
reached step 1.
Both audio
and video
elements can be used for both audio
and video. The main difference between the two is simply that the audio
element has
no playback area for visual content (such as video or captions), whereas the video
element does.
Except where otherwise explicitly specified, the task source for all the tasks queued in this section and its subsections is the media element event task source of the media element in question.
4.7.14.1. Error codes
- media .
error
-
Returns a
MediaError
object representing the current error state of the element.Returns null if there is no error.
All media elements have an associated error status, which
records the last error the element encountered since its resource selection algorithm was last invoked. The error
attribute, on getting, must return the MediaError
object created for this last error, or null if there has not been an
error.
interface MediaError { const unsigned short MEDIA_ERR_ABORTED = 1; const unsigned short MEDIA_ERR_NETWORK = 2; const unsigned short MEDIA_ERR_DECODE = 3; const unsigned short MEDIA_ERR_SRC_NOT_SUPPORTED = 4; readonly attribute unsigned short code; };
- media .
error
.code
-
Returns the current error’s error code, from the list below.
The code
attribute of a MediaError
object must return the code for the error, which must be one of the
following:
MEDIA_ERR_ABORTED
(numeric value 1)- The fetching process for the media resource was aborted by the user agent at the user’s request.
MEDIA_ERR_NETWORK
(numeric value 2)- A network error of some description caused the user agent to stop fetching the media resource, after the resource was established to be usable.
MEDIA_ERR_DECODE
(numeric value 3)- An error of some description occurred while decoding the media resource, after the resource was established to be usable.
MEDIA_ERR_SRC_NOT_SUPPORTED
(numeric value 4)- The media resource indicated by the
src
attribute or assigned media provider object was not suitable.
4.7.14.2. Location of the media resource
The src
content attribute on media elements gives the address of the media resource (video, audio) to show. The
attribute, if present, must contain a valid non-empty URL potentially surrounded by
spaces.
The crossorigin
content attribute on media elements is a CORS settings attribute.
If a media element is created with a src
attribute, the user agent must immediately invoke the media element’s resource selection
algorithm.
If a src
attribute of a media element is set
or changed, the user agent must invoke the media element’s media element load
algorithm. (Removing the src
attribute does
not do this, even if there are source
elements present.)
The src
IDL attribute on media elements must reflect the content attribute of the same
name.
The crossOrigin
IDL attribute must reflect the crossorigin
content attribute.
A media provider object is an object that can represent a media resource,
separate from a URL. MediaStream
objects, MediaSource
objects, Blob
objects, and File
objects are all media provider objects.
Each media element can have an assigned media provider object, which is a media provider object. When a media element is created, it has no assigned media provider object.
- media .
srcObject
[ = source ] - Allows the media element to be assigned a media provider object.
- media .
currentSrc
-
Returns the URL of the current media resource, if any.
Returns the empty string when there is no media resource, or it doesn’t have a URL.
The currentSrc
IDL attribute is initially
the empty string. Its value is changed by the resource
selection algorithm defined below.
The srcObject
IDL attribute, on getting,
must return the element’s assigned media provider object, if any, or null otherwise. On
setting, it must set the element’s assigned media provider object to the new value, and
then invoke the element’s media element load algorithm.
There are three ways to specify a media resource, the srcObject
IDL attribute, the src
content attribute, and source
elements. The IDL attribute takes priority, followed by the content attribute, followed by the
elements.
4.7.14.3. MIME types
A media resource can be described in terms of its type, specifically a MIME type, in some cases with a codecs
parameter. (Whether the codecs
parameter is allowed or not depends on the MIME type.) [RFC6381]
Types are usually somewhat incomplete descriptions; for example "video/mpeg
" doesn’t say anything except what the container type is, and even a
type like "video/mp4; codecs="avc1.42E01E, mp4a.40.2"
" doesn’t
include information like the actual bitrate (only the maximum bitrate). Thus, given a type, a user
agent can often only know whether it might be able to play media of that type (with
varying levels of confidence), or whether it definitely cannot play media of that
type.
A type that the user agent knows it cannot render is one that describes a resource that the user agent definitely does not support, for example because it doesn’t recognize the container type, or it doesn’t support the listed codecs.
The MIME type "application/octet-stream
" with no parameters is never a type that the user agent knows it cannot render. User agents must treat that type
as equivalent to the lack of any explicit Content-Type metadata when it is used to label a potential media resource.
Only the MIME type "application/octet-stream
" with no
parameters is special-cased here; if any parameter appears with it, it will be treated just like
any other MIME type. This is a deviation from the rule that unknown MIME type parameters should be ignored.
- media .
canPlayType
(type) -
Returns the empty string (a negative response), "maybe", or "probably" based on how confident the user agent is that it can play media resources of the given type.
The canPlayType(type)
method must return the
empty string if type is a type that the user agent knows it cannot
render or is the type "application/octet-stream
"; it must return "probably
" if the user agent is confident
that the type represents a media resource that it can render if used in with this audio
or video
element; and it must return "maybe
" otherwise. Implementors are encouraged
to return "maybe
" unless the type can be
confidently established as being supported or not. Generally, a user agent should never return
"probably
" for a type that allows the codecs
parameter if that parameter is not present.
video
element or a plugin:
<section id="video"> <p><a href="playing-cats.nfv">Download video</a></p> </section> <script> var videoSection = document.getElementById('video'); var videoElement = document.createElement('video'); var support = videoElement.canPlayType('video/x-new-fictional-format;codecs="kittens,bunnies"'); if (support != "probably" && "New Fictional Video Plugin" in navigator.plugins) { // not confident of browser support // but we have a plugin // so use plugin instead videoElement = document.createElement("embed"); } else if (support == "") { // no support from browser and no plugin // do nothing videoElement = null; } if (videoElement) { while (videoSection.hasChildNodes()) videoSection.removeChild(videoSection.firstChild); videoElement.setAttribute("src", "playing-cats.nfv"); videoSection.appendChild(videoElement); } </script>
The type
attribute of the source
element allows the user agent to avoid downloading resources that use formats
it cannot render.
4.7.14.4. Network states
- media .
networkState
-
Returns the current state of network activity for the element, from the codes in the list below.
As media elements interact with the network, their current
network activity is represented by the networkState
attribute. On getting, it must
return the current network state of the element, which must be one of the following values:
NETWORK_EMPTY
(numeric value 0)- The element has not yet been initialized. All attributes are in their initial states.
NETWORK_IDLE
(numeric value 1)- The element's resource selection algorithm is active and has selected a resource, but it is not actually using the network at this time.
NETWORK_LOADING
(numeric value 2)- The user agent is actively trying to download data.
NETWORK_NO_SOURCE
(numeric value 3)- The element's resource selection algorithm is active, but it has not yet found a resource to use.
The resource selection algorithm defined
below describes exactly when the networkState
attribute changes value and what events fire to indicate changes in this state.
4.7.14.5. Loading the media resource
- media .
load
() -
Causes the element to reset and start selecting and loading a new media resource from scratch.
All media elements have an autoplaying flag, which must begin in the true state, and a delaying-the-load-event flag, which must begin in the false state. While the delaying-the-load-event flag is true, the element must delay the load event of its document.
When the load()
method on a media element is invoked, the user agent must run the media element load
algorithm.
The media element load algorithm consists of the following steps.
- Abort any already-running instance of the resource selection algorithm for this element.
-
If there are any tasks from the media element’s media element event task source in one of the task queues, then remove those tasks.
Basically, pending events and callbacks for the media element are discarded when the media element starts loading a new resource.
- If the media element’s
networkState
is set toNETWORK_LOADING
orNETWORK_IDLE
, queue a task to fire a simple event namedabort
at the media element. -
If the media element’s
networkState
is not set toNETWORK_EMPTY
, then run these substeps:- Queue a task to fire a simple event named emptied at the media element.
- If a fetching process is in progress for the media element, the user agent should stop it.
- If the media element’s assigned media provider object is a
MediaSource
object, then detach it. - Forget the media element’s media-resource-specific tracks.
- If
readyState
is not set toHAVE_NOTHING
, then set it to that state. - If the
paused
attribute is false, then set it to true. - If
seeking
is true, set it to false. -
Set the current playback position to 0.
Set the official playback position to 0.
If this changed the official playback position, then queue a task to fire a simple event named
timeupdate
at the media element. - Set the initial playback position to 0.
- Set the timeline offset to Not-a-Number (NaN).
-
Update the
duration
attribute to Not-a-Number (NaN).The user agent will not fire a
durationchange
event for this particular change of the duration.
- Set the
playbackRate
attribute to the value of thedefaultPlaybackRate
attribute. - Set the
error
attribute to null and the autoplaying flag to true. - Invoke the media element’s resource selection algorithm.
-
Playback of any previously playing media resource for this element stops.
The resource selection algorithm for a media element is as follows. This algorithm is always invoked as part of a task, but one of the first steps in the algorithm is to return and continue running the remaining steps in parallel. In addition, this algorithm interacts closely with the event loop mechanism; in particular, it has synchronous sections (which are triggered as part of the event loop algorithm). Steps in such sections are marked with ⌛.
- Set the element’s
networkState
attribute to theNETWORK_NO_SOURCE
value. - Set the element’s show poster flag to true.
- Set the media element’s delaying-the-load-event flag to true (this delays the load event).
- in parallel await a stable state, allowing the task that invoked this algorithm to continue. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)
-
⌛ If the media element’s blocked-on-parser flag is false, then populate the list of pending text tracks.
-
⌛ If the media element has an assigned media provider object, then let mode be object.
⌛ Otherwise, if the media element has no assigned media provider object but has a
src
attribute, then let mode be attribute.⌛ Otherwise, if the media element does not have an assigned media provider object and does not have a
src
attribute, but does have asource
element child, then let mode be children and let candidate be the first suchsource
element child in tree order.⌛ Otherwise the media element has no assigned media provider object and has neither a
src
attribute nor asource
element child: set thenetworkState
toNETWORK_EMPTY
, and abort these steps; the synchronous section ends. - ⌛ Set the media element’s
networkState
toNETWORK_LOADING
. - ⌛ Queue a task to fire a simple event named
loadstart
at the media element. -
Run the appropriate steps from the following list:
- If mode is object
-
- ⌛ Set the
currentSrc
attribute to the empty string. - End the synchronous section, continuing the remaining steps in parallel.
- Run the resource fetch algorithm with the assigned media provider object. If that algorithm returns without aborting this one, then the load failed.
- Failed with media provider: Reaching this step indicates that the media resource failed to load. Queue a task to run the dedicated media source failure steps.
- Wait for the task queued by the previous step to have executed.
- Abort these steps. The element won’t attempt to load another resource until this algorithm is triggered again.
- ⌛ Set the
- If mode is attribute
-
- ⌛ If the
src
attribute’s value is the empty string, then end the synchronous section, and jump down to the failed with attribute step below. - ⌛ Let absolute URL be the absolute URL that
would have resulted from parsing the URL specified by the
src
attribute’s value relative to the media element when thesrc
attribute was last changed. - ⌛ If absolute URL was obtained successfully, set the
currentSrc
attribute to absolute URL. - End the synchronous section, continuing the remaining steps in parallel.
- If absolute URL was obtained successfully, run the resource fetch algorithm with absolute URL. If that algorithm returns without aborting this one, then the load failed.
- Failed with attribute: Reaching this step indicates that the media resource failed to load or that the given URL could not be resolved. Queue a task to run the dedicated media source failure steps.
- Wait for the task queued by the previous step to have executed.
- Abort these steps. The element won’t attempt to load another resource until this algorithm is triggered again.
- ⌛ If the
- Otherwise (mode is children)
-
-
⌛ Let pointer be a position defined by two adjacent nodes in the media element’s child list, treating the start of the list (before the first child in the list, if any) and end of the list (after the last child in the list, if any) as nodes in their own right. One node is the node before pointer, and the other node is the node after pointer. Initially, let pointer be the position between the candidate node and the next node, if there are any, or the end of the list, if it is the last node.
As nodes are inserted and removed into the media element, pointer must be updated as follows:
- If a new node is inserted between the two nodes that define pointer
- Let pointer be the point between the node before pointer and the new node. In other words, insertions at pointer go after pointer.
- If the node before pointer is removed
- Let pointer be the point between the node after pointer and the node before the node after pointer. In other words, pointer doesn’t move relative to the remaining nodes.
- If the node after pointer is removed
- Let pointer be the point between the node before pointer and the node after the node before pointer. Just as with the previous case, pointer doesn’t move relative to the remaining nodes.
Other changes don’t affect pointer.
- ⌛ Process candidate: If candidate does not have a
src
attribute, or if itssrc
attribute’s value is the empty string, then end the synchronous section, and jump down to the failed with elements step below. - ⌛ Let absolute URL be the absolute URL that
would have resulted from parsing the URL specified by candidate’s
src
attribute’s value relative to the candidate when thesrc
attribute was last changed. - ⌛ If absolute URL was not obtained successfully, then end the synchronous section, and jump down to the failed with elements step below.
- ⌛ If candidate has a
type
attribute whose value, when parsed as a MIME type (including any codecs described by thecodecs
parameter, for types that define that parameter), represents a type that the user agent knows it cannot render, then end the synchronous section, and jump down to the failed with elements step below. - ⌛ Set the
currentSrc
attribute to absolute URL. - End the synchronous section, continuing the remaining steps in parallel.
- Run the resource fetch algorithm with absolute URL. If that algorithm returns without aborting this one, then the load failed.
- Failed with elements: Queue a task to fire a simple
event named
error
at the candidate element. - Await a stable state. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)
- ⌛ Forget the media element’s media-resource-specific tracks.
- ⌛ Find next candidate: Let candidate be null.
- ⌛ Search loop: If the node after pointer is the end of the list, then jump to the waiting step below.
- ⌛ If the node after pointer is a
source
element, let candidate be that element. - ⌛ Advance pointer so that the node before pointer is now the node that was after pointer, and the node after pointer is the node after the node that used to be after pointer, if any.
- ⌛ If candidate is null, jump back to the search loop step. Otherwise, jump back to the process candidate step.
- ⌛ Waiting: Set the element’s
networkState
attribute to theNETWORK_NO_SOURCE
value. - ⌛ Set the element’s show poster flag to true.
- ⌛ Queue a task to set the element’s delaying-the-load-event flag to false. This stops delaying the load event.
- End the synchronous section, continuing the remaining steps in parallel.
- Wait until the node after pointer is a node other than the end of the list. (This step might wait forever.)
- Await a stable state. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)
- ⌛ Set the element’s delaying-the-load-event flag back to true (this delays the load event again, in case it hasn’t been fired yet).
- ⌛ Set the
networkState
back toNETWORK_LOADING
. - ⌛ Jump back to the find next candidate step above.
-
The dedicated media source failure steps are the following steps:
- Set the
error
attribute to a newMediaError
object whosecode
attribute is set toMEDIA_ERR_SRC_NOT_SUPPORTED
. - Forget the media element’s media-resource-specific tracks.
- Set the element’s
networkState
attribute to theNETWORK_NO_SOURCE
value. - Set the element’s show poster flag to true.
- Fire a simple event named
error
at the media element. - Set the element’s delaying-the-load-event flag to false. This stops delaying the load event.
The resource fetch algorithm for a media element and a given absolute URL or media provider object is as follows:
- If the algorithm was invoked with a URL, then let mode be remote, otherwise let mode be local.
- If mode is remote, then let the current media resource be the resource given by the absolute URL passed to this algorithm; otherwise, let the current media resource be the resource given by the media provider object. Either way, the current media resource is now the element’s media resource.
- Remove all media-resource-specific text tracks from the media element’s list of pending text tracks, if any.
-
Run the appropriate steps from the following list:
- If mode is remote
-
-
Optionally, run the following substeps. This is the expected behavior if the user agent intends to not attempt to fetch the resource until the user requests it explicitly (e.g., as a way to implement the
preload
attribute’snone
keyword).- Set the
networkState
toNETWORK_IDLE
. - Queue a task to fire a simple event named
suspend
at the element. - Queue a task to set the element’s delaying-the-load-event flag to false. This stops delaying the load event.
- Wait for the task to be run.
- Wait for an implementation-defined event (e.g., the user requesting that the media element begin playback).
- Set the element’s delaying-the-load-event flag back to true (this delays the load event again, in case it hasn’t been fired yet).
- Set the
networkState
toNETWORK_LOADING
.
- Set the
-
Let request be the result of creating a potential-CORS request given current media resource’s absolute URL and the media element’s
crossorigin
content attribute value.Set request’s client to the media element’s node document’s
Window
object’s environment settings object and type to "audio
" if the media element is anaudio
element and to "video
" otherwise.Fetch request.
The response’s unsafe response obtained in this fashion, if any, contains the media data. It can be CORS-same-origin or CORS-cross-origin; this affects whether subtitles referenced in the media data are exposed in the API and, for
video
elements, whether acanvas
gets tainted when the video is drawn on it.The stall timeout is a user-agent defined length of time, which should be about three seconds. When a media element that is actively attempting to obtain media data has failed to receive any data for a duration equal to the stall timeout, the user agent must queue a task to fire a simple event named
stalled
at the element.User agents may allow users to selectively block or slow media data downloads. When a media element’s download has been blocked altogether, the user agent must act as if it was stalled (as opposed to acting as if the connection was closed). The rate of the download may also be throttled automatically by the user agent, e.g., to balance the download with other connections sharing the same bandwidth.
User agents may decide to not download more content at any time, e.g., after buffering five minutes of a one hour media resource, while waiting for the user to decide whether to play the resource or not, while waiting for user input in an interactive resource, or when the user navigates away from the page. When a media element’s download has been suspended, the user agent must queue a task, to set the
networkState
toNETWORK_IDLE
and fire a simple event namedsuspend
at the element. If and when downloading of the resource resumes, the user agent must queue a task to set thenetworkState
toNETWORK_LOADING
. Between the queuing of these tasks, the load is suspended (soprogress
events don’t fire, as described above).The
preload
attribute provides a hint regarding how much buffering the author thinks is advisable, even in the absence of theautoplay
attribute.When a user agent decides to completely suspend a download, e.g., if it is waiting until the user starts playback before downloading any further content, the user agent must queue a task to set the element’s delaying-the-load-event flag to false. This stops delaying the load event.
The user agent may use whatever means necessary to fetch the resource (within the constraints put forward by this and other specifications); for example, reconnecting to the server in the face of network errors, using HTTP range retrieval requests, or switching to a streaming protocol. The user agent must consider a resource erroneous only if it has given up trying to fetch it.
To determine the format of the media resource, the user agent must use the rules for sniffing audio and video specifically.
While the load is not suspended (see below), every 350ms (±200ms) or for every byte received, whichever is least frequent, queue a task to fire a simple event named
progress
at the element.The networking task source tasks to process the data as it is being fetched must each immediately queue a task to run the first appropriate steps from the media data processing steps list below. (A new task is used for this so that the work described below occurs relative to the media element event task source rather than the networking task source.)
When the networking task source has queued the last task as part of fetching the media resource (i.e., once the download has completed), if the fetching process completes without errors, including decoding the media data, and if all of the data is available to the user agent without network access, then, the user agent must move on to the final step below. This might never happen, e.g., when streaming an infinite resource such as Web radio, or if the resource is longer than the user agent’s ability to cache data.
While the user agent might still need network access to obtain parts of the media resource, the user agent must remain on this step.
For example, if the user agent has discarded the first half of a video, the user agent will remain at this step even once the playback has ended, because there is always the chance the user will seek back to the start. In fact, in this situation, once playback has ended, the user agent will end up firing a
suspend
event, as described earlier.
-
- Otherwise (mode is local)
-
The resource described by the current media resource, if any, contains the media data. It is CORS-same-origin.
If the current media resource is a raw data stream (e.g., from a
File
object), then to determine the format of the media resource, the user agent must use the rules for sniffing audio and video specifically. Otherwise, if the data stream is pre-decoded, then the format is the format given by the relevant specification.Whenever new data for the current media resource becomes available, queue a task to run the first appropriate steps from the media data processing steps list below.
When the current media resource is permanently exhausted (e.g., all the bytes of a
Blob
have been processed), if there were no decoding errors, then the user agent must move on to the final step below. This might never happen, e.g., if the current media resource is aMediaStream
.
The media data processing steps list is as follows:
- If the media data cannot be fetched at all, due to network errors, causing the
user agent to give up trying to fetch the resource
- If the media data can be fetched but is found by inspection to be in an unsupported format, or can otherwise not be rendered at all
-
DNS errors, HTTP 4xx and 5xx errors (and equivalents in other protocols), and other fatal network errors that occur before the user agent has established whether the current media resource is usable, as well as the file using an unsupported container format, or using unsupported codecs for all the data, must cause the user agent to execute the following steps:
- The user agent should cancel the fetching process.
- Abort this subalgorithm, returning to the resource selection algorithm.
- If the media resource is found to have an audio track
-
- Create an
AudioTrack
object to represent the audio track. - Update the media element’s
audioTracks
attribute’sAudioTrackList
object with the newAudioTrack
object. - Let enable be unknown.
-
If either the media resource or the address of the current media resource indicate a particular set of audio tracks to enable, or if the user agent has information that would facilitate the selection of specific audio tracks to improve the user’s experience, then: if this audio track is one of the ones to enable, then set enable to true, otherwise, set enable to false.
This could be triggered by Media Fragments URI fragment identifier syntax, but it could also be triggered e.g., by the user agent selecting a 5.1 surround sound audio track over a stereo audio track. [MEDIA-FRAGS]
- If enable is still unknown, then, if the media element does not yet have an enabled audio track, then set enable to true, otherwise, set enable to false.
- If enable is true, then enable this audio track, otherwise, do not enable this audio track.
- Fire a trusted event with the name
addtrack
, that does not bubble and is not cancelable, and that uses theTrackEvent
interface, with thetrack
attribute initialized to the newAudioTrack
object, at thisAudioTrackList
object.
- Create an
- If the media resource is found to have a video track
-
- Create a
VideoTrack
object to represent the video track. - Update the media element’s
videoTracks
attribute’sVideoTrackList
object with the newVideoTrack
object. - Let enable be unknown.
-
If either the media resource or the address of the current media resource indicate a particular set of video tracks to enable, or if the user agent has information that would facilitate the selection of specific video tracks to improve the user’s experience, then: if this video track is the first such video track, then set enable to true, otherwise, set enable to false.
This could again be triggered by Media Fragments URI fragment identifier syntax.
- If enable is still unknown, then, if the media element does not yet have a selected video track, then set enable to true, otherwise, set enable to false.
- If enable is true, then select this track and unselect any
previously selected video tracks, otherwise, do not select this video track. If other tracks
are unselected, then a
change
event will be fired. - Fire a trusted event with the name
addtrack
, that does not bubble and is not cancelable, and that uses theTrackEvent
interface, with thetrack
attribute initialized to the newVideoTrack
object, at thisVideoTrackList
object.
- Create a
- Once enough of the media data has been fetched to determine the duration of the media resource, its dimensions, and other metadata
-
This indicates that the resource is usable. The user agent must follow these substeps:
-
Establish the media timeline for the purposes of the current playback position and the earliest possible position, based on the media data.
-
Update the timeline offset to the date and time that corresponds to the zero time in the media timeline established in the previous step, if any. If no explicit time and date is given by the media resource, the timeline offset must be set to Not-a-Number (NaN).
- Set the current playback position and the official playback position to the earliest possible position.
-
Update the
duration
attribute with the time of the last frame of the resource, if known, on the media timeline established above. If it is not known (e.g., a stream that is in principle infinite), update theduration
attribute to the value positive Infinity.The user agent will queue a task to fire a simple event named
durationchange
at the element at this point. -
For
video
elements, set thevideoWidth
andvideoHeight
attributes, and queue a task to fire a simple event namedresize
at the media element.Further
resize
events will be fired if the dimensions subsequently change. -
Set the
readyState
attribute toHAVE_METADATA
.A
loadedmetadata
DOM event will be fired as part of setting thereadyState
attribute to a new value. - Let jumped be false.
- If the media element’s default playback start position is greater than zero, then seek to that time, and let jumped be true.
- Let the media element’s default playback start position be zero.
- Let the initial playback position be zero.
-
If either the media resource or the address of the current media resource indicate a particular start time, then set the initial playback position to that time and, if jumped is still false, seek to that time and let jumped be true.
For example, with media formats that support the Media Fragments URI fragment identifier syntax, the fragment identifier can be used to indicate a start position. [MEDIA-FRAGS]
- If there is no enabled audio track, then
enable an audio track. This will cause a
change
event to be fired. - If there is no selected video track,
then select a video track. This will cause a
change
event to be fired.
Once the
readyState
attribute reachesHAVE_CURRENT_DATA
, after theloadeddata
event has been fired, set the element’s delaying-the-load-event flag to false. This stops delaying the load event.A user agent that is attempting to reduce network usage while still fetching the metadata for each media resource would also stop buffering at this point, following the rules described previously, which involve the
networkState
attribute switching to theNETWORK_IDLE
value and asuspend
event firing.The user agent is required to determine the duration of the media resource and go through this step before playing.
-
- Once the entire media resource has been fetched (but potentially before any of it has been decoded)
-
Fire a simple event named
progress
at the media element.Set the
networkState
toNETWORK_IDLE
and fire a simple event namedsuspend
at the media element.If the user agent ever discards any media data and then needs to resume the network activity to obtain it again, then it must queue a task to set the
networkState
toNETWORK_LOADING
.If the user agent can keep the media resource loaded, then the algorithm will continue to its final step below, which aborts the algorithm.
- If the connection is interrupted after some media data has been received, causing the user agent to give up trying to fetch the resource
-
Fatal network errors that occur after the user agent has established whether the current media resource is usable (i.e., once the media element’s
readyState
attribute is no longerHAVE_NOTHING
) must cause the user agent to execute the following steps:- The user agent should cancel the fetching process.
- Set the
error
attribute to a newMediaError
object whosecode
attribute is set toMEDIA_ERR_NETWORK
. - Set the element’s
networkState
attribute to theNETWORK_IDLE
value. - Set the element’s delaying-the-load-event flag to false. This stops delaying the load event.
- Fire a simple event named
error
at the media element. - Abort the overall resource selection algorithm.
- If the media data is corrupted
-
Fatal errors in decoding the media data that occur after the user agent has established whether the current media resource is usable (i.e., once the media element’s
readyState
attribute is no longerHAVE_NOTHING
) must cause the user agent to execute the following steps:- The user agent should cancel the fetching process.
- Set the
error
attribute to a newMediaError
object whosecode
attribute is set toMEDIA_ERR_DECODE
. - Set the element’s
networkState
attribute to theNETWORK_IDLE
value. - Set the element’s delaying-the-load-event flag to false. This stops delaying the load event.
- Fire a simple event named
error
at the media element. - Abort the overall resource selection algorithm.
- If the media data fetching process is aborted by the user
-
The fetching process is aborted by the user, e.g., because the user pressed a "stop" button, the user agent must execute the following steps. These steps are not followed if the
load()
method itself is invoked while these steps are running, as the steps above handle that particular kind of abort.- The user agent should cancel the fetching process.
- Set the
error
attribute to a newMediaError
object whosecode
attribute is set toMEDIA_ERR_ABORTED
. - Fire a simple event named
abort
at the media element. -
If the media element’s
readyState
attribute has a value equal toHAVE_NOTHING
, set the element’snetworkState
attribute to theNETWORK_EMPTY
value, set the element’s show poster flag to true, and fire a simple event named emptied at the element.Otherwise, set the element’s
networkState
attribute to theNETWORK_IDLE
value. - Set the element’s delaying-the-load-event flag to false. This stops delaying the load event.
- Abort the overall resource selection algorithm.
- If the media data can be fetched but has non-fatal errors or uses, in part, codecs that are unsupported, preventing the user agent from rendering the content completely correctly but not preventing playback altogether
-
The server returning data that is partially usable but cannot be optimally rendered must cause the user agent to render just the bits it can handle, and ignore the rest.
- If the media resource is found to declare a media-resource-specific text track that the user agent supports
-
If the media data is CORS-same-origin, run the steps to expose a media-resource-specific text track with the relevant data.
Cross-origin videos do not expose their subtitles, since that would allow attacks such as hostile sites reading subtitles from confidential videos on a user’s intranet.
- Final step: If the user agent ever reaches this step (which can only happen if the entire resource gets loaded and kept available): abort the overall resource selection algorithm.
When a media element is to forget the media element’s media-resource-specific
tracks, the user agent must remove from the media element’s list of text
tracks all the media-resource-specific
text tracks, then empty the media element’s audioTracks
attribute’s AudioTrackList
object,
then empty the media element’s videoTracks
attribute’s VideoTrackList
object. No events (in particular, no removetrack
events) are fired as part of this; the error
and emptied events, fired by the algorithms that invoke this one, can be used instead.
The preload
attribute is an enumerated
attribute. The following table lists the keywords and states for the attribute — the
keywords in the left column map to the states in the cell in the second column on the same row as
the keyword. The attribute can be changed even once the media resource is being
buffered or played; the descriptions in the table below are to be interpreted with that in
mind.
Keyword | State | Brief description |
---|---|---|
none
| None | Hints to the user agent that either the author does not expect the user to need the media resource, or that the server wants to minimize unnecessary traffic. This state does not provide a hint regarding how aggressively to actually download the media resource if buffering starts anyway (e.g., once the user hits "play"). |
metadata
| Metadata | Hints to the user agent that the author does not expect the user to need the media resource, but that fetching the resource metadata (dimensions, track list, duration, etc), and maybe even the first few frames, is reasonable. If the user agent precisely fetches no more than the metadata, then the media element will end up with its readyState attribute set to HAVE_METADATA ; typically though, some frames will be obtained as well and it will probably be HAVE_CURRENT_DATA or HAVE_FUTURE_DATA .
When the media resource is playing, hints to the user agent that bandwidth is to be considered scarce, e.g., suggesting throttling the download so that the media data is obtained at the slowest possible rate that still maintains consistent playback.
|
auto
| Automatic | Hints to the user agent that the user agent can put the user’s needs first without risk to the server, up to and including optimistically downloading the entire resource. |
The empty string is also a valid keyword, and maps to the Automatic state. The attribute’s missing value default is user-agent defined, though the Metadata state is suggested as a compromise between reducing server load and providing an optimal user experience.
Authors might switch the attribute from "none
" or "metadata
" to "auto
" dynamically once the user begins playback. For
example, on a page with many videos this might be used to indicate that the many videos are not to
be downloaded unless requested, but that once one is requested it is to be downloaded
aggressively.
The preload
attribute is intended to provide a hint to
the user agent about what the author thinks will lead to the best user experience. The attribute
may be ignored altogether, for example based on explicit user preferences or based on the
available connectivity.
The preload
IDL attribute must reflect the content attribute of the same name, limited to only known
values.
The autoplay
attribute can override the preload
attribute (since if the media plays, it naturally
has to buffer first, regardless of the hint given by the preload
attribute). Including both is not an error, however.
- media .
buffered
-
Returns a
TimeRanges
object that represents the ranges of the media resource that the user agent has buffered.
The buffered
attribute must return a new
static normalized TimeRanges
object that represents the ranges of the media resource, if any, that the user agent has buffered, at the time the attribute
is evaluated. Users agents must accurately determine the ranges available, even for media streams
where this can only be determined by tedious inspection.
Typically this will be a single range anchored at the zero point, but if, e.g., the user agent uses HTTP range requests in response to seeking, then there could be multiple ranges.
User agents may discard previously buffered data.
Thus, a time position included within a range of the objects return by the buffered
attribute at one time can end up being not included in
the range(s) of objects returned by the same attribute at later times.
4.7.14.6. Offsets into the media resource
- media .
duration
-
Returns the length of the media resource, in seconds, assuming that the start of the media resource is at time zero.
Returns NaN if the duration isn’t available.
Returns Infinity for unbounded streams.
- media .
currentTime
[ = value ] -
Returns the official playback position, in seconds.
Can be set, to seek to the given time.
A media resource has a media timeline that maps times (in seconds) to positions in the media resource. The origin of a timeline is its earliest defined position. The duration of a timeline is its last defined position.
Establishing the media timeline: If the media resource somehow specifies an explicit timeline whose
origin is not negative (i.e., gives each frame a specific time offset and gives the first frame a
zero or positive offset), then the media timeline should be that timeline. (Whether
the media resource can specify a timeline or not depends on the media resource’s format.) If the media resource specifies an
explicit start time and date, then that time and date should be considered the zero point
in the media timeline; the timeline offset will be the time and date,
exposed using the getStartDate()
method.
If the media resource has a discontinuous timeline, the user agent must extend the timeline used at the start of the resource across the entire resource, so that the media timeline of the media resource increases linearly starting from the earliest possible position (as defined below), even if the underlying media data has out-of-order or even overlapping time codes.
For example, if two clips have been concatenated into one video file, but the video format exposes the original times for the two clips, the video data might expose a timeline that goes, say, 00:15..00:29 and then 00:05..00:38. However, the user agent would not expose those times; it would instead expose the times as 00:15..00:29 and 00:29..01:02, as a single video.
In the rare case of a media resource that does not have an explicit timeline, the
zero time on the media timeline should correspond to the first frame of the media resource. In the even rarer case of a media resource with no
explicit timings of any kind, not even frame durations, the user agent must itself determine the
time for each frame in a user-agent-defined manner.
An example of a file format with no explicit timeline but with explicit frame
durations is the Animated GIF format. An example of a file format with no explicit timings at all
is the JPEG-push format (multipart/x-mixed-replace
with JPEG frames, often
used as the format for MJPEG streams).
If, in the case of a resource with no timing information, the user agent will nonetheless be able to seek to an earlier point than the first frame originally provided by the server, then the zero time should correspond to the earliest seekable time of the media resource; otherwise, it should correspond to the first frame received from the server (the point in the media resource at which the user agent began receiving the stream).
At the time of writing, there is no known format that lacks explicit frame time offsets yet still supports seeking to a frame before the first frame sent by the server.
getStartDate()
method would always return the date that the
broadcast started; this would allow controllers to display real times in their scrubber (e.g.,
"2:30pm") rather than a time relative to when the broadcast began ("8 months, 4 hours, 12
minutes, and 23 seconds").
Consider a stream that carries a video with several concatenated fragments, broadcast by a
server that does not allow user agents to request specific times but instead just streams the
video data in a predetermined order, with the first frame delivered always being identified as
the frame with time zero. If a user agent connects to this stream and receives fragments defined
as covering timestamps 2010-03-20 23:15:00 UTC to 2010-03-21 00:05:00 UTC and 2010-02-12 14:25:00
UTC to 2010-02-12 14:35:00 UTC, it would expose this with a media timeline starting
at 0s and extending to 3,600s (one hour). Assuming the streaming server disconnected at the end
of the second clip, the duration
attribute would then
return 3,600. The getStartDate()
method would return a Date
object with a time corresponding to 2010-03-20 23:15:00 UTC. However, if a
different user agent connected five minutes later, it would (presumably) receive
fragments covering timestamps 2010-03-20 23:20:00 UTC to 2010-03-21 00:05:00 UTC and 2010-02-12
14:25:00 UTC to 2010-02-12 14:35:00 UTC, and would expose this with a media timeline starting at 0s and extending to 3,300s (fifty five minutes). In this case, the getStartDate()
method would return a Date
object
with a time corresponding to 2010-03-20 23:20:00 UTC.
In both of these examples, the seekable
attribute
would give the ranges that the controller would want to actually display in its UI; typically, if
the servers don’t support seeking to arbitrary times, this would be the range of time from the
moment the user agent connected to the stream up to the latest frame that the user agent has
obtained; however, if the user agent starts discarding earlier information, the actual range
might be shorter.
In any case, the user agent must ensure that the earliest possible position (as defined below) using the established media timeline, is greater than or equal to zero.
The media timeline also has an associated clock. Which clock is used is user-agent defined, and may be media resource-dependent, but it should approximate the user’s wall clock.
Media elements have a current playback position, which must initially (i.e., in the absence of media data) be zero seconds. The current playback position is a time on the media timeline.
Media elements also have an official playback position, which must initially be set to zero seconds. The official playback position is an approximation of the current playback position that is kept stable while scripts are running.
Media elements also have a default playback start position, which must initially be set to zero seconds. This time is used to allow the element to be seeked even before the media is loaded.
Each media element has a show poster flag. When a media element is created, this flag must be set to true. This flag is used to control when the
user agent is to show a poster frame for a video
element instead of showing the video
contents.
The currentTime
attribute must, on
getting, return the media element’s default playback start position,
unless that is zero, in which case it must return the element’s official playback
position. The returned value must be expressed in seconds. On setting, if the media element’s readyState
is HAVE_NOTHING
,
then it must set the media element’s default playback start position to the new value; otherwise, it must
set the official playback position to the new value and then seek to the new value. The new value must be interpreted as being in
seconds.
Media elements have an initial playback position, which must initially (i.e., in the absence of media data) be zero seconds. The initial playback position is updated when a media resource is loaded. The initial playback position is a time on the media timeline.
If the media resource is a streaming resource, then the user agent might be unable to obtain certain parts of the resource after it has expired from its buffer. Similarly, some media resources might have a media timeline that doesn’t start at zero. The earliest possible position is the earliest position in the stream or resource that the user agent can ever obtain again. It is also a time on the media timeline.
The earliest possible position is not explicitly exposed in the API;
it corresponds to the start time of the first range in the seekable
attribute’s TimeRanges
object, if any, or
the current playback position otherwise.
When the earliest possible position changes, then: if the current playback
position is before the earliest possible position, the user agent must seek to the earliest possible position; otherwise, if
the user agent has not fired a timeupdate
event at the
element in the past 15 to 250ms and is not still running event handlers for such an event, then
the user agent must queue a task to fire a simple event named timeupdate
at the element.
Because of the above requirement and the requirement in the resource fetch algorithm that kicks in when the metadata of the clip becomes known, the current playback position can never be less than the earliest possible position.
If at any time the user agent learns that an audio or video track has ended and all media
data relating to that track corresponds to parts of the media timeline that
are before the earliest possible position, the user agent may queue a
task to first remove the track from the audioTracks
attribute’s AudioTrackList
object or the videoTracks
attribute’s VideoTrackList
object as
appropriate and then fire a trusted event with the name removetrack
, that does not bubble and is not cancelable, and that
uses the TrackEvent
interface, with the track
attribute initialized to the AudioTrack
or VideoTrack
object representing the track, at the media element’s
aforementioned AudioTrackList
or VideoTrackList
object.
The duration
attribute must return the time
of the end of the media resource, in seconds, on the media timeline. If
no media data is available, then the attributes must return the Not-a-Number (NaN)
value. If the media resource is not known to be bounded (e.g., streaming radio, or a
live event with no announced end time), then the attribute must return the positive Infinity
value.
The user agent must determine the duration of the media resource before playing
any part of the media data and before setting readyState
to a value equal to or greater than HAVE_METADATA
, even if doing so requires fetching multiple
parts of the resource.
When the length of the media resource changes to a known value (e.g., from being unknown to known, or from a previously established length to a new length) the user agent must queue a task to fire a simple event named durationchange at the media element. (The event is not fired when the duration is reset as part of loading a new media resource.) If the duration is changed such that the current playback position ends up being greater than the time of the end of the media resource, then the user agent must also seek to the time of the end of the media resource.
If an "infinite" stream ends for some reason, then the duration would change
from positive Infinity to the time of the last frame or sample in the stream, and the durationchange
event would be fired. Similarly, if the
user agent initially estimated the media resource’s duration instead of determining
it precisely, and later revises the estimate based on new information, then the duration would
change and the durationchange
event would be
fired.
Some video files also have an explicit date and time corresponding to the zero time in the media timeline, known as the timeline offset. Initially, the timeline offset must be set to Not-a-Number (NaN).
The getStartDate()
method must return a new Date
object representing the current timeline offset.
The loop
attribute is a boolean
attribute that, if specified, indicates that the media element is to seek back
to the start of the media resource upon reaching the end.
The loop
IDL attribute must reflect the content attribute of the same name.
4.7.14.7. Ready states
- media .
readyState
-
Returns a value that expresses the current state of the element with respect to rendering the current playback position, from the codes in the list below.
Media elements have a ready state, which describes to what degree they are ready to be rendered at the current playback position. The possible values are as follows; the ready state of a media element at any particular time is the greatest value describing the state of the element:
HAVE_NOTHING
(numeric value 0)- No information regarding the media resource is available. No data for the current playback position is available. Media elements whose
networkState
attribute are set toNETWORK_EMPTY
are always in theHAVE_NOTHING
state. HAVE_METADATA
(numeric value 1)- Enough of the resource has been obtained that the duration of the resource is available.
In the case of a
video
element, the dimensions of the video are also available. No media data is available for the immediate current playback position. HAVE_CURRENT_DATA
(numeric value 2)- Data for the immediate current playback position is available, but either not
enough data is available that the user agent could successfully advance the current
playback position in the direction of playback at all without immediately
reverting to the
HAVE_METADATA
state, or there is no more data to obtain in the direction of playback. For example, in video this corresponds to the user agent having data from the current frame, but not the next frame, when the current playback position is at the end of the current frame; and to when playback has ended. HAVE_FUTURE_DATA
(numeric value 3)- Data for the immediate current playback position is available, as well as
enough data for the user agent to advance the current playback position in the direction of playback at least a little without immediately reverting to the
HAVE_METADATA
state, and the text tracks are ready. For example, in video this corresponds to the user agent having data for at least the current frame and the next frame when the current playback position is at the instant in time between the two frames, or to the user agent having the video data for the current frame and audio data to keep playing at least a little when the current playback position is in the middle of a frame. The user agent cannot be in this state if playback has ended, as the current playback position can never advance in this case. HAVE_ENOUGH_DATA
(numeric value 4)-
All the conditions described for the
HAVE_FUTURE_DATA
state are met, and, in addition, either of the following conditions is also true:- The user agent estimates that data is being fetched at a rate where the current playback position, if it were to advance at the effective playback rate, would not overtake the available data before playback reaches the end of the media resource.
- The user agent has entered a state where waiting longer will not result in further data being obtained, and therefore nothing would be gained by delaying playback any further. (For example, the buffer might be full.)
In practice, the difference between HAVE_METADATA
and HAVE_CURRENT_DATA
is negligible. Really the only time
the difference is relevant is when painting a video
element onto a canvas
, where it distinguishes the case where something will be drawn (HAVE_CURRENT_DATA
or greater) from the case where
nothing is drawn (HAVE_METADATA
or less). Similarly,
the difference between HAVE_CURRENT_DATA
(only
the current frame) and HAVE_FUTURE_DATA
(at least
this frame and the next) can be negligible (in the extreme, only one frame). The only time that
distinction really matters is when a page provides an interface for "frame-by-frame"
navigation.
When the ready state of a media element whose networkState
is not NETWORK_EMPTY
changes, the user agent must follow the steps
given below:
-
Apply the first applicable set of substeps from the following list:
- If the previous ready state was
HAVE_NOTHING
, and the new ready state isHAVE_METADATA
-
Queue a task to fire a simple event named
loadedmetadata
at the element.Before this task is run, as part of the event loop mechanism, the rendering will have been updated to resize the
video
element if appropriate. - If the previous ready state was
HAVE_METADATA
and the new ready state isHAVE_CURRENT_DATA
or greater -
If this is the first time this occurs for this media element since the
load()
algorithm was last invoked, the user agent must queue a task to fire a simple event namedloadeddata
at the element.If the new ready state is
HAVE_FUTURE_DATA
orHAVE_ENOUGH_DATA
, then the relevant steps below must then be run also. - If the previous ready state was
HAVE_FUTURE_DATA
or more, and the new ready state isHAVE_CURRENT_DATA
or less -
If the media element was potentially playing before its
readyState
attribute changed to a value lower thanHAVE_FUTURE_DATA
, and the element has not ended playback, and playback has not stopped due to errors, paused for user interaction, or paused for in-band content, the user agent must queue a task to fire a simple event namedtimeupdate
at the element, and queue a task to fire a simple event namedwaiting
at the element. - If the previous ready state was
HAVE_CURRENT_DATA
or less, and the new ready state isHAVE_FUTURE_DATA
-
The user agent must queue a task to fire a simple event named
canplay
at the element.If the element’s
paused
attribute is false, the user agent must queue a task to fire a simple event namedplaying
at the element. - If the new ready state is
HAVE_ENOUGH_DATA
-
If the previous ready state was
HAVE_CURRENT_DATA
or less, the user agent must queue a task to fire a simple event namedcanplay
at the element, and, if the element’spaused
attribute is false, queue a task to fire a simple event namedplaying
at the element.If the autoplaying flag is true, and the
paused
attribute is true, and the media element has anautoplay
attribute specified, and the media element’s node document’s active sandboxing flag set does not have the sandboxed automatic features browsing context flag set, then the user agent may also run the following substeps:- Set the
paused
attribute to false. - If the element’s show poster flag is true, set it to false and run the time marches on steps.
- Queue a task to fire a simple event named
play
at the element. - Queue a task to fire a simple event named
playing
at the element. - Set the autoplaying flag to false.
User agents do not need to support autoplay, and it is suggested that user agents honor user preferences on the matter. Authors are urged to use the
autoplay
attribute rather than using script to force the video to play, so as to allow the user to override the behavior if so desired.In any case, the user agent must finally queue a task to fire a simple event named
canplaythrough
at the element. - Set the
- If the previous ready state was
It is possible for the ready state of a media element to jump between these states
discontinuously. For example, the state of a media element can jump straight from HAVE_METADATA
to HAVE_ENOUGH_DATA
without passing through the HAVE_CURRENT_DATA
and HAVE_FUTURE_DATA
states.
The readyState
IDL attribute must, on
getting, return the value described above that describes the current ready state of the media element.
The autoplay
attribute is a boolean
attribute. When present, the user agent (as described in the algorithm
described herein) will automatically begin playback of the media resource as
soon as it can do so without stopping.
Authors are urged to use the autoplay
attribute rather than using script to trigger automatic playback, as this allows the user to
override the automatic playback when it is not desired, e.g., when using a screen reader. Authors
are also encouraged to consider not using the automatic playback behavior at all, and instead to
let the user agent wait for the user to start playback explicitly.
The autoplay
IDL attribute must reflect the content attribute of the same name.
4.7.14.8. Playing the media resource
- media .
paused
-
Returns true if playback is paused; false otherwise.
- media .
ended
-
Returns true if playback has reached the end of the media resource.
- media .
defaultPlaybackRate
[ = value ] -
Returns the default rate of playback, for when the user is not fast-forwarding or reversing through the media resource.
Can be set, to change the default rate of playback.
The default rate has no direct effect on playback, but if the user switches to a fast-forward mode, when they return to the normal playback mode, it is expected that the rate of playback will be returned to the default rate of playback.
- media .
playbackRate
[ = value ] -
Returns the current rate playback, where 1.0 is normal speed.
Can be set, to change the rate of playback.
- media .
played
-
Returns a
TimeRanges
object that represents the ranges of the media resource that the user agent has played. - media .
play
() -
Sets the
paused
attribute to false, loading the media resource and beginning playback if necessary. If the playback had ended, will restart it from the start. - media .
pause
() -
Sets the
paused
attribute to true, loading the media resource if necessary.
The paused
attribute represents whether the media element is paused or not. The attribute must initially be true.
A media element is a blocked media element if its readyState
attribute is in the HAVE_NOTHING
state, the HAVE_METADATA
state, or the HAVE_CURRENT_DATA
state, or if the element has paused for user interaction or paused for in-band content.
A media element is said to be potentially playing when its paused
attribute is false, the element has not ended
playback, playback has not stopped due to errors, and the element is not a blocked media element.
A waiting
DOM event can be fired as a result of an element that is potentially playing stopping playback due to its readyState
attribute changing to a value lower than HAVE_FUTURE_DATA
.
A media element is said to have ended playback when:
- The element’s
readyState
attribute isHAVE_METADATA
or greater, and -
Either:
- The current playback position is the end of the media resource, and
- The direction of playback is forwards, and
- The media element does not have a
loop
attribute specified.
Or:
- The current playback position is the earliest possible position, and
- The direction of playback is backwards.
The ended
attribute must return true if, the
last time the event loop reached step 1, the media element had ended playback and the direction of playback was forwards, and false
otherwise.
A media element is said to have stopped due to errors when the
element’s readyState
attribute is HAVE_METADATA
or greater, and the user agent encounters a non-fatal error during the processing of the media data, and due to that error, is not able to play the content at the current playback position.
A media element is said to have paused for user interaction when its paused
attribute is false, the readyState
attribute is either HAVE_FUTURE_DATA
or HAVE_ENOUGH_DATA
and the user agent has reached a point
in the media resource where the user has to make a selection for the resource to
continue.
It is possible for a media element to have both ended playback and paused for user interaction at the same time.
When a media element that is potentially playing stops playing
because it has paused for user interaction, the user agent must queue a
task to fire a simple event named timeupdate
at the element.
A media element is said to have paused for in-band content when its paused
attribute is false, the readyState
attribute is either HAVE_FUTURE_DATA
or HAVE_ENOUGH_DATA
and the user agent has suspended
playback of the media resource in order to play content that is temporally anchored
to the media resource and has a non-zero length, or to play content that is
temporally anchored to a segment of the media resource but has a length longer than
that segment.
One example of when a media element would be paused for in-band content is when the user agent is playing audio descriptions from an external WebVTT file, and the synthesized speech generated for a cue is longer than the time between the text track cue start time and the text track cue end time.
When the current playback position reaches the end of the media resource when the direction of playback is forwards, then the user agent must follow these steps:
- If the media element has a
loop
attribute specified, then seek to the earliest possible position of the media resource and abort these steps. - As defined above, the
ended
IDL attribute starts returning true once the event loop returns to step 1. - Queue a task to fire a simple event named
timeupdate
at the media element. - Queue a task that, if the media element has still ended
playback, and the direction of playback is still forwards, and paused is false, changes paused to true and fires a
simple event named
pause
at the media element. - Queue a task to fire a simple event named
ended
at the media element.
When the current playback position reaches the earliest possible
position of the media resource when the direction of playback is
backwards, then the user agent must only queue a task to fire a simple
event named timeupdate
at the element.
The word "reaches" here does not imply that the current playback position needs to have changed during normal playback; it could be via seeking, for instance.
The defaultPlaybackRate
attribute
gives the desired speed at which the media resource is to play, as a multiple of its
intrinsic speed. The attribute is mutable: on getting it must return the last value it was set to,
or 1.0 if it hasn’t yet been set; on setting the attribute must be set to the new value.
The defaultPlaybackRate
is used
by the user agent when it exposes a user
interface to the user.
The playbackRate
attribute gives the effective playback rate which is the speed at which the media resource plays, as a multiple
of its intrinsic speed. If it is not equal to the defaultPlaybackRate
, then the implication is that the
user is using a feature such as fast forward or slow motion playback. The attribute is mutable: on
getting it must return the last value it was set to, or 1.0 if it hasn’t yet been set; on setting
the attribute must be set to the new value, and the playback will change speed (if the element is potentially playing).
When the defaultPlaybackRate
or playbackRate
attributes change value (either by
being set by script or by being changed directly by the user agent, e.g., in response to user
control) the user agent must queue a task to fire a simple event named ratechange
at the media element.
The played
attribute must return a new static normalized TimeRanges
object that represents the ranges of points on the media timeline of the media resource reached through the usual monotonic
increase of the current playback position during normal playback, if any, at the time
the attribute is evaluated.
When the play()
method on a media element is invoked, the user agent must run the following steps.
- If the media element’s
networkState
attribute has the valueNETWORK_EMPTY
, invoke the media element’s resource selection algorithm. -
If the playback has ended and the direction of playback is forwards, seek to the earliest possible position of the media resource.
This will cause the user agent to queue a task to fire a simple event named
timeupdate
at the media element. -
If the media element’s
paused
attribute is true, run the following substeps:- Change the value of
paused
to false. - If the show poster flag is true, set the element’s show poster flag to false and run the time marches on steps.
- Queue a task to fire a simple event named
play
at the element. -
If the media element’s
readyState
attribute has the valueHAVE_NOTHING
,HAVE_METADATA
, orHAVE_CURRENT_DATA
, queue a task to fire a simple event namedwaiting
at the element.Otherwise, the media element’s
readyState
attribute has the valueHAVE_FUTURE_DATA
orHAVE_ENOUGH_DATA
: queue a task to fire a simple event namedplaying
at the element.
- Change the value of
- Set the media element’s autoplaying flag to false.
When the pause()
method is invoked, and when
the user agent is required to pause the media element, the user agent must run the
following steps:
- If the media element’s
networkState
attribute has the valueNETWORK_EMPTY
, invoke the media element’s resource selection algorithm. - Run the internal pause steps for the media element.
The internal pause steps for a media element are as follows:
- Set the media element’s autoplaying flag to false.
-
If the media element’s
paused
attribute is false, run the following steps:- Change the value of
paused
to true. - Queue a task to fire a simple
event named
timeupdate
at the element. - Queue a task to fire a simple
event named
pause
at the element. - Set the official playback position to the current playback position.
- Change the value of
The effective playback rate is just the element’s playbackRate
.
If the effective playback rate is positive or zero, then the direction of playback is forwards. Otherwise, it is backwards.
When a media element is potentially playing and
its Document
is a fully active Document
, its current
playback position must increase monotonically at effective playback rate units
of media time per unit time of the media timeline’s clock. (This specification always
refers to this as an increase, but that increase could actually be a decrease if
the effective playback rate is negative.)
The effective playback rate can be 0.0, in which case the current playback position doesn’t move, despite playback not being paused (paused
doesn’t become true, and the pause
event doesn’t fire).
This specification doesn’t define how the user agent achieves the appropriate playback rate — depending on the protocol and media available, it is plausible that the user agent could negotiate with the server to have the server provide the media data at the appropriate rate, so that (except for the period between when the rate is changed and when the server updates the stream’s playback rate) the client doesn’t actually have to drop or interpolate any frames.
Any time the user agent provides a stable state, the official playback position must be set to the current playback position.
While the direction of playback is backwards, any corresponding audio must be muted. While the effective playback rate is so low or so high that the user agent cannot play audio usefully, the corresponding audio must also be muted. If the effective playback rate is not 1.0, the user agent may apply pitch adjustments to the audio as necessary to render it faithfully.
Media elements that are potentially playing while not in a Document
must not play any video, but should play any
audio component. Media elements must not stop playing just because all references to them have
been removed; only once a media element is in a state where no further audio could ever be played
by that element may the element be garbage collected.
It is possible for an element to which no explicit references exist to play audio, even if such an element is not still actively playing: for instance, a media element whose media resource has no audio tracks could eventually play audio again if it had an event listener that changes the media resource.
Each media element has a list of newly introduced cues, which must be initially empty. Whenever a text track cue is added to the list of cues of a text track that is in the list of text tracks for a media element, that cue must be added to the media element’s list of newly introduced cues. Whenever a text track is added to the list of text tracks for a media element, all of the cues in that text track’s list of cues must be added to the media element’s list of newly introduced cues. When a media element’s list of newly introduced cues has new cues added while the media element’s show poster flag is not set, then the user agent must run the time marches on steps.
When a text track cue is removed from the list of cues of a text track that is in the list of text tracks for a media element, and whenever a text track is removed from the list of text tracks of a media element, if the media element’s show poster flag is not set, then the user agent must run the time marches on steps.
When the current playback position of a media element changes (e.g., due to playback or seeking), the user agent must run the time marches on steps. If the current playback position changes while the steps are running, then the user agent must wait for the steps to complete, and then must immediately rerun the steps. (These steps are thus run as often as possible or needed — if one iteration takes a long time, this can cause certain cues to be skipped over as the user agent rushes ahead to "catch up".)
The time marches on steps are as follows:
- Let current cues be a list of cues, initialized to contain all the cues of all the or showing text tracks of the media element (not the disabled ones) whose start times are less than or equal to the current playback position and whose end times are greater than the current playback position.
- Let other cues be a list of cues, initialized to contain all the cues of and showing text tracks of the media element that are not present in current cues.
- Let last time be the current playback position at the time this algorithm was last run for this media element, if this is not the first time it has run.
- If the current playback position has, since the last time this algorithm was run, only changed through its usual monotonic increase during normal playback, then let missed cues be the list of cues in other cues whose start times are greater than or equal to last time and whose end times are less than or equal to the current playback position. Otherwise, let missed cues be an empty list.
- Remove all the cues in missed cues that are also in the media element’s list of newly introduced cues, and then empty the element’s list of newly introduced cues.
-
If the time was reached through the usual monotonic increase of the current playback
position during normal playback, and if the user agent has not fired a
timeupdate
event at the element in the past 15 to 250ms and is not still running event handlers for such an event, then the user agent must queue a task to fire a simple event namedtimeupdate
at the element. (In the other cases, such as explicit seeks, relevant events get fired as part of the overall process of changing the current playback position.)The event thus is not to be fired faster than about 66Hz or slower than 4Hz (assuming the event handlers don’t take longer than 250ms to run). User agents are encouraged to vary the frequency of the event based on the system load and the average cost of processing the event each time, so that the UI updates are not any more frequent than the user agent can comfortably handle while decoding the video.
- If all of the cues in current cues have their text track cue active flag set, none of the cues in other cues have their text track cue active flag set, and missed cues is empty, then abort these steps.
-
If the time was reached through the usual monotonic increase of the current playback position during normal playback, and there are cues in other cues that have their text track cue pause-on-exit flag set and that either have their text track cue active flag set or are also in missed cues, then immediately pause the media element.
In the other cases, such as explicit seeks, playback is not paused by going past the end time of a cue, even if that cue has its text track cue pause-on-exit flag set.
-
Let events be a list of tasks, initially empty. Each task in this list will be associated with a text track, a text track cue, and a time, which are used to sort the list before the tasks are queued.
Let affected tracks be a list of text tracks, initially empty.
When the steps below say to prepare an event named event for a text track cue target with a time time, the user agent must run these substeps:
- Let track be the text track with which the text track cue target is associated.
- Create a task to fire a simple event named event at target.
- Add the newly created task to events, associated with the time time, the text track track, and the text track cue target.
- Add track to affected tracks.
- For each text track cue in missed
cues, prepare an event named
enter
for theTextTrackCue
object with the text track cue start time. - For each text track cue in other
cues that either has its text track cue active flag set or is in missed cues, prepare an event named
exit
for theTextTrackCue
object with the later of the text track cue end time and the text track cue start time. - For each text track cue in current
cues that does not have its text track cue active flag set, prepare an
event named
enter
for theTextTrackCue
object with the text track cue start time. -
Sort the tasks in events in ascending time order (tasks with earlier times first).
Further sort tasks in events that have the same time by the relative text track cue order of the text track cues associated with these tasks.
Finally, sort tasks in events that have the same time and same text track cue order by placing tasks that fire
enter
events before those that fireexit
events. - Queue each task in events, in list order.
- Sort affected tracks in the same order as the text tracks appear in the media element’s list of text tracks, and remove duplicates.
- For each text track in affected tracks, in the list
order, queue a task to fire a simple event named
cuechange
at theTextTrack
object, and, if the text track has a correspondingtrack
element, to then fire a simple event namedcuechange
at thetrack
element as well. - Set the text track cue active flag of all the cues in the current cues, and unset the text track cue active flag of all the cues in the other cues.
- Run the rules for updating the text track rendering of each of the text tracks in affected tracks that are showing, providing the text track’s text track language as the fallback language if it is not the empty string. For example, for text tracks based on WebVTT, the rules for updating the display of WebVTT text tracks. [WEBVTT]
For the purposes of the algorithm above, a text track cue is considered to be part of a text track only if it is listed in the text track list of cues, not merely if it is associated with the text track.
If the media element’s node document stops being a fully active document, then the playback will stop until the document is active again.
When a media element is removed
from a Document
, the user agent must run the following steps:
- Await a stable state, allowing the task that removed the media element from the
Document
to continue. The synchronous section consists of all the remaining steps of this algorithm. (Steps in the synchronous section are marked with ⌛.) - ⌛ If the media element is in a
Document
, abort these steps. - ⌛ Run the internal pause steps for the media element.
4.7.14.9. Seeking
- media .
seeking
-
Returns true if the user agent is currently seeking.
- media .
seekable
-
Returns a
TimeRanges
object that represents the ranges of the media resource to which it is possible for the user agent to seek. - media .
fastSeek
( time ) -
Seeks to near the given time as fast as possible, trading precision for speed. (To seek to a precise time, use the
currentTime
attribute.)This does nothing if the media resource has not been loaded.
The seeking
attribute must initially have the
value false.
The fastSeek()
method must seek to the time given by the method’s argument, with the approximate-for-speed flag set.
When the user agent is required to seek to a particular new playback position in the media resource, optionally with the approximate-for-speed flag set, it means that the user agent must run the following steps. This algorithm interacts closely with the event loop mechanism; in particular, it has a synchronous section (which is triggered as part of the event loop algorithm). Steps in that section are marked with ⌛.
- Set the media element’s show poster flag to false.
- If the media element’s
readyState
isHAVE_NOTHING
, abort these steps. - If the element’s
seeking
IDL attribute is true, then another instance of this algorithm is already running. Abort that other instance of the algorithm without waiting for the step that it is running to complete. - Set the
seeking
IDL attribute to true. - If the seek was in response to a DOM method call or setting of an IDL attribute, then continue the script. The remainder of these steps must be run in parallel. With the exception of the steps marked with ⌛, they could be aborted at any time by another instance of this algorithm being invoked.
- If the new playback position is later than the end of the media resource, then let it be the end of the media resource instead.
- If the new playback position is less than the earliest possible position, let it be that position instead.
- If the (possibly now changed) new playback position is not in one of
the ranges given in the
seekable
attribute, then let it be the position in one of the ranges given in theseekable
attribute that is the nearest to the new playback position. If two positions both satisfy that constraint (i.e., the new playback position is exactly in the middle between two ranges in theseekable
attribute) then use the position that is closest to the current playback position. If there are no ranges given in theseekable
attribute then set theseeking
IDL attribute to false and abort these steps. -
If the approximate-for-speed flag is set, adjust the new playback position to a value that will allow for playback to resume promptly. If new playback position before this step is before current playback position, then the adjusted new playback position must also be before the current playback position. Similarly, if the new playback position before this step is after current playback position, then the adjusted new playback position must also be after the current playback position.
For example, the user agent could snap to a nearby key frame, so that it doesn’t have to spend time decoding then discarding intermediate frames before resuming playback.
- Queue a task to fire a simple event named
seeking
at the element. -
Set the current playback position to the new playback position.
If the media element was potentially playing immediately before it started seeking, but seeking caused its
readyState
attribute to change to a value lower thanHAVE_FUTURE_DATA
, then awaiting
event will be fired at the element.This step sets the current playback position, and thus can immediately trigger other conditions, such as the rules regarding when playback "reaches the end of the media resource" (part of the logic that handles looping), even before the user agent is actually able to render the media data for that position (as determined in the next step).
The
currentTime
attribute returns the official playback position, not the current playback position, and therefore gets updated before script execution, separate from this algorithm. - Wait until the user agent has established whether or not the media data for the new playback position is available, and, if it is, until it has decoded enough data to play back that position.
- Await a stable state. The synchronous section consists of all the remaining steps of this algorithm. (Steps in the synchronous section are marked with ⌛.)
- ⌛ Set the
seeking
IDL attribute to false. - ⌛ Run the time marches on steps.
- ⌛ Queue a task to fire a simple event named
timeupdate
at the element. - ⌛ Queue a task to fire a simple event named
seeked
at the element.
The seekable
attribute must return a new
static normalized TimeRanges
object that represents the ranges of the media resource, if any, that the user agent is able to seek to, at the time the
attribute is evaluated.
If the user agent can seek to anywhere in the media resource, e.g.,
because it is a simple movie file and the user agent and the server support HTTP Range requests,
then the attribute would return an object with one range, whose start is the time of the first
frame (the earliest possible position, typically zero), and whose end is the same as
the time of the first frame plus the duration
attribute’s
value (which would equal the time of the last frame, and might be positive Infinity).
The range might be continuously changing, e.g., if the user agent is buffering a sliding window on an infinite stream. This is the behavior seen with DVRs viewing live TV, for instance.
User agents should adopt a very liberal and optimistic view of what is seekable. User agents should also buffer recent content where possible to enable seeking to be fast.
For instance, consider a large video file served on an HTTP server without support for HTTP Range requests. A browser could implement this by only buffering the current frame and data obtained for subsequent frames, never allow seeking, except for seeking to the very start by restarting the playback. However, this would be a poor implementation. A high quality implementation would buffer the last few minutes of content (or more, if sufficient storage space is available), allowing the user to jump back and rewatch something surprizing without any latency, and would in addition allow arbitrary seeking by reloading the file from the start if necessary, which would be slower but still more convenient than having to literally restart the video and watch it all the way through just to get to an earlier unbuffered spot.
Media resources might be internally scripted or interactive. Thus, a media element could play in a non-linear fashion. If this happens, the user agent must act as if the algorithm for seeking was used whenever the current playback position changes in a discontinuous fashion (so that the relevant events fire).
4.7.14.10. Media resources with multiple media tracks
A media resource can have multiple embedded audio and video tracks. For example, in addition to the primary video and audio tracks, a media resource could have foreign-language dubbed dialogs, director’s commentaries, audio descriptions, alternative angles, or sign-language overlays.
- media .
audioTracks
-
Returns an
AudioTrackList
object representing the audio tracks available in the media resource. - media .
videoTracks
-
Returns a
VideoTrackList
object representing the video tracks available in the media resource.
The audioTracks
attribute of a media element must return a live AudioTrackList
object
representing the audio tracks available in the media element’s media
resource.
The videoTracks
attribute of a media element must return a live VideoTrackList
object
representing the video tracks available in the media element’s media
resource.
There are only ever one AudioTrackList
object and one VideoTrackList
object per media element, even if another media
resource is loaded into the element: the objects are reused. (The AudioTrack
and VideoTrack
objects are not, though.)
<script> function loadVideo(url, container) { var video = document.createElement('video'); video.src = url; video.autoplay = true; video.controls = true; container.appendChild(video); video.onloadedmetadata = function (event) { for (var i = 0; i < video.videoTracks.length; i += 1) { if (video.videoTracks[i].kind == 'sign') { var sign = document.createElement('video'); sign.src = url + '#track=' + video.videoTracks[i].id; sign.autoplay = true; container.appendChild(sign); return; } } }; } </script>
4.7.14.10.1. AudioTrackList
and VideoTrackList
objects
The AudioTrackList
and VideoTrackList
interfaces are used by
attributes defined in the previous section.
interface AudioTrackList : EventTarget { readonly attribute unsigned long length; getter AudioTrack (unsigned long index); AudioTrack? getTrackById(DOMString id); attribute EventHandler onchange; attribute EventHandler onaddtrack; attribute EventHandler onremovetrack; };
interface AudioTrack { readonly attribute DOMString id; readonly attribute DOMString kind; readonly attribute DOMString label; readonly attribute DOMString language; attribute boolean enabled; };
interface VideoTrackList : EventTarget { readonly attribute unsigned long length; getter VideoTrack (unsigned long index); VideoTrack? getTrackById(DOMString id); readonly attribute long selectedIndex; attribute EventHandler onchange; attribute EventHandler onaddtrack; attribute EventHandler onremovetrack; };
interface VideoTrack { readonly attribute DOMString id; readonly attribute DOMString kind; readonly attribute DOMString label; readonly attribute DOMString language; attribute boolean selected; };
- media .
audioTracks
.length
- media .
videoTracks
.length
- media .
-
Returns the number of tracks in the list.
- audioTrack = media .
audioTracks
[index]- videoTrack = media .
videoTracks
[index] - videoTrack = media .
-
Returns the specified
AudioTrack
orVideoTrack
object. - audioTrack = media .
audioTracks
.getTrackById
( id )- videoTrack = media .
videoTracks
.getTrackById
( id ) - videoTrack = media .
-
Returns the
AudioTrack
orVideoTrack
object with the given identifier, or null if no track has that identifier. - audioTrack .
id
- videoTrack .
id
- videoTrack .
-
Returns the ID of the given track. This is the ID that can be used with a fragment identifier if the format supports the Media Fragments URI syntax, and that can be used with the
getTrackById()
method. [MEDIA-FRAGS] - audioTrack .
kind
- videoTrack .
kind
- videoTrack .
-
Returns the category the given track falls into. The possible track categories are given below.
- audioTrack .
label
- videoTrack .
label
- videoTrack .
-
Returns the label of the given track, if known, or the empty string otherwise.
- audioTrack .
language
- videoTrack .
language
- videoTrack .
-
Returns the language of the given track, if known, or the empty string otherwise.
- audioTrack .
enabled
[ = value ] -
Returns true if the given track is active, and false otherwise.
Can be set, to change whether the track is enabled or not. If multiple audio tracks are enabled simultaneously, they are mixed.
- media .
videoTracks
.selectedIndex
-
Returns the index of the currently selected track, if any, or -1 otherwise.
- videoTrack .
selected
[ = value ] -
Returns true if the given track is active, and false otherwise.
Can be set, to change whether the track is selected or not. Either zero or one video track is selected; selecting a new track while a previous one is selected will unselect the previous one.
An AudioTrackList
object represents a dynamic list of zero or more audio tracks,
of which zero or more can be enabled at a time. Each audio track is represented by an AudioTrack
object.
A VideoTrackList
object represents a dynamic list of zero or more video tracks, of
which zero or one can be selected at a time. Each video track is represented by a VideoTrack
object.
Tracks in AudioTrackList
and VideoTrackList
objects must be
consistently ordered. If the media resource is in a format that defines an order,
then that order must be used; otherwise, the order must be the relative order in which the tracks
are declared in the media resource. The order used is called the natural order of the list.
Each track in one of these objects thus has an index; the first has the index 0, and each subsequent track is numbered one higher than the previous one. If a media resource dynamically adds or removes audio or video tracks, then the indices of the tracks will change dynamically. If the media resource changes entirely, then all the previous tracks will be removed and replaced with new tracks.
The AudioTrackList.length
and VideoTrackList.length
attributes must return
the number of tracks represented by their objects at the time of getting.
The supported property indices of AudioTrackList
and VideoTrackList
objects at any instant are the numbers from zero to the number of
tracks represented by the respective object minus one, if any tracks are represented. If an AudioTrackList
or VideoTrackList
object represents no tracks, it has no supported property indices.
To determine the value of an indexed property for a given index index in an AudioTrackList
or VideoTrackList
object list, the user agent must return the AudioTrack
or VideoTrack
object that represents the indexth track in list.
The AudioTrackList.getTrackById(id)
and VideoTrackList.getTrackById(id)
methods must return the first AudioTrack
or VideoTrack
object (respectively) in the AudioTrackList
or VideoTrackList
object (respectively) whose identifier is equal to the value of the id argument (in the natural order of the list, as defined above). When no
tracks match the given argument, the methods must return null.
The AudioTrack
and VideoTrack
objects represent specific tracks of a media resource. Each track can have an identifier, category, label, and language.
These aspects of a track are permanent for the lifetime of the track; even if a track is removed
from a media resource’s AudioTrackList
or VideoTrackList
objects, those aspects do not change.
In addition, AudioTrack
objects can each be enabled or disabled; this is the audio
track’s enabled state. When an AudioTrack
is created, its enabled state must be set to false (disabled). The resource fetch
algorithm can override this.
Similarly, a single VideoTrack
object per VideoTrackList
object can
be selected, this is the video track’s selection state. When a VideoTrack
is
created, its selection state must be set to false (not selected). The resource fetch algorithm can override this.
The AudioTrack.id
and VideoTrack.id
attributes must return the identifier
of the track, if it has one, or the empty string otherwise. If the media resource is
in a format that supports the Media Fragments URI fragment identifier syntax, the
identifier returned for a particular track must be the same identifier that would enable the track
if used as the name of a track in the track dimension of such a fragment identifier. [MEDIA-FRAGS] [INBANDTRACKS]
For example, in Ogg files, this would be the Name header field of the track. [OGGSKELETON]
The AudioTrack.kind
and VideoTrack.kind
attributes must return the category
of the track, if it has one, or the empty string otherwise.
The category of a track is the string given in the first column of the table below that is the
most appropriate for the track based on the definitions in the table’s second and third columns,
as determined by the metadata included in the track in the media resource. The cell
in the third column of a row says what the category given in the cell in the first column of that
row applies to; a category is only appropriate for an audio track if it applies to audio tracks,
and a category is only appropriate for video tracks if it applies to video tracks. Categories must
only be returned for AudioTrack
objects if they are appropriate for audio, and must
only be returned for VideoTrack
objects if they are appropriate for video.
The AudioTrack.label
and VideoTrack.label
attributes must return the label
of the track, if it has one, or the empty string otherwise. [INBANDTRACKS]
The AudioTrack.language
and VideoTrack.language
attributes must return the
BCP 47 language tag of the language of the track, if it has one, or the empty string otherwise. If
the user agent is not able to express that language as a BCP 47 language tag (for example because
the language information in the media resource’s format is a free-form string without
a defined interpretation), then the method must return the empty string, as if the track had no
language.
Source attribute values for id, kind, label and language of multitrack audio and video tracks as described for the relevant media resource format. [INBANDTRACKS]
The AudioTrack.enabled
attribute, on
getting, must return true if the track is currently enabled, and false otherwise. On setting, it
must enable the track if the new value is true, and disable it otherwise. (If the track is no
longer in an AudioTrackList
object, then the track being enabled or disabled has no
effect beyond changing the value of the attribute on the AudioTrack
object.)
Whenever an audio track in an AudioTrackList
that was
disabled is enabled, and whenever one that was enabled is disabled, the user agent must queue a task to fire a simple event named change
at the AudioTrackList
object.
An audio track that has no data for a particular position on the media timeline, or that does not exist at that position, must be interpreted as being silent at that point on the timeline.
The VideoTrackList.selectedIndex
attribute
must return the index of the currently selected track, if any. If the VideoTrackList
object does not currently represent any tracks, or if none of the tracks are selected, it must
instead return -1.
The VideoTrack.selected
attribute, on
getting, must return true if the track is currently selected, and false otherwise. On setting, it
must select the track if the new value is true, and unselect it otherwise. If the track is in a VideoTrackList
, then all the other VideoTrack
objects in that list must
be unselected. (If the track is no longer in a VideoTrackList
object, then the track
being selected or unselected has no effect beyond changing the value of the attribute on the VideoTrack
object.)
Whenever a track in a VideoTrackList
that was previously
not selected is selected, and whenever the selected track in a VideoTrackList
is
unselected without a new track being selected in its stead, the user agent must queue a task to fire a simple
event named change
at the VideoTrackList
object. This task must be queued before the task that fires
the resize
event, if any.
A video track that has no data for a particular position on the media timeline must be interpreted as being fully transparent black at that point on the timeline, with the same dimensions as the last frame before that position, or, if the position is before all the data for that track, the same dimensions as the first frame for that track. A track that does not exist at all at the current position must be treated as if it existed but had no data.
For instance, if a video has a track that is only introduced after one hour of playback, and the user selects that track then goes back to the start, then the user agent will act as if that track started at the start of the media resource but was simply transparent until one hour in.
The following are the event handlers (and their corresponding event handler event types) that must be supported, as event handler IDL attributes,
by all objects implementing the AudioTrackList
and VideoTrackList
interfaces:
Event handler | Event handler event type |
---|---|
onchange
| change
|
onaddtrack
| addtrack
|
onremovetrack
| removetrack
|
4.7.14.10.2. Selecting specific audio and video tracks declaratively
The audioTracks
and videoTracks
attributes allow scripts to select which track
should play, but it is also possible to select specific tracks declaratively, by specifying
particular tracks in the fragment identifier of the URL of the media
resource. The format of the fragment identifier depends on the MIME type of
the media resource. [RFC2046] [URL]
<video src="myvideo#track=Alternative"></video>
4.7.14.11. Timed text tracks
4.7.14.11.1. Text track model
A media element can have a group of associated text tracks, known as the media element’s list of text tracks. The text tracks are sorted as follows:
- The text tracks corresponding to
track
element children of the media element, in tree order. - Any text tracks added using the
addTextTrack()
method, in the order they were added, oldest first. - Any media-resource-specific text tracks (text tracks corresponding to data in the media resource), in the order defined by the media resource’s format specification.
A text track consists of:
- The kind of text track
-
This decides how the track is handled by the user agent. The kind is represented by a string. The possible strings are:
The kind of track can change dynamically, in the case of a text track corresponding to a
track
element. - A label
-
This is a human-readable string intended to identify the track for the user.
The label of a track can change dynamically, in the case of a text track corresponding to a
track
element.When a text track label is the empty string, the user agent should automatically generate an appropriate label from the text track’s other properties (e.g., the kind of text track and the text track’s language) for use in its user interface. This automatically-generated label is not exposed in the API.
- An in-band metadata track dispatch type
-
This is a string extracted from the media resource specifically for in-band metadata tracks to enable such tracks to be dispatched to different scripts in the document.
For example, a traditional TV station broadcast streamed on the Web and augmented with Web-specific interactive features could include text tracks with metadata for ad targeting, trivia game data during game shows, player states during sports games, recipe information during food programs, and so forth. As each program starts and ends, new tracks might be added or removed from the stream, and as each one is added, the user agent could bind them to dedicated script modules using the value of this attribute.
Other than for in-band metadata text tracks, the in-band metadata track dispatch type is the empty string. How this value is populated for different media formats is described in steps to expose a media-resource-specific text track.
- A language
-
This is a string (a BCP 47 language tag) representing the language of the text track’s cues. [BCP47]
The language of a text track can change dynamically, in the case of a text track corresponding to a
track
element. - A readiness state
-
One of the following:
- Not loaded
-
Indicates that the text track’s cues have not been obtained.
- Loading
-
Indicates that the text track is loading and there have been no fatal errors encountered so far. Further cues might still be added to the track by the parser.
- Loaded
-
Indicates that the text track has been loaded with no fatal errors.
- Failed to load
-
Indicates that the text track was enabled, but when the user agent attempted to obtain it, this failed in some way (e.g., URL could not be resolved, network error, unknown text track format). Some or all of the cues are likely missing and will not be obtained.
The readiness state of a text track changes dynamically as the track is obtained.
- A mode
-
One of the following:
- Disabled
-
Indicates that the text track is not active. Other than for the purposes of exposing the track in the DOM, the user agent is ignoring the text track. No cues are active, no events are fired, and the user agent will not attempt to obtain the track’s cues.
- Hidden
-
Indicates that the text track is active, but that the user agent is not actively displaying the cues. If no attempt has yet been made to obtain the track’s cues, the user agent will perform such an attempt momentarily. The user agent is maintaining a list of which cues are active, and events are being fired accordingly.
- Showing
-
Indicates that the text track is active. If no attempt has yet been made to obtain the track’s cues, the user agent will perform such an attempt momentarily. The user agent is maintaining a list of which cues are active, and events are being fired accordingly. In addition, for text tracks whose kind is
subtitles
orcaptions
, the cues are being overlaid on the video as appropriate; for text tracks whose kind isdescriptions
, the user agent is making the cues available to the user in a non-visual fashion; and for text tracks whose kind ischapters
, the user agent is making available to the user a mechanism by which the user can navigate to any point in the media resource by selecting a cue.
- A list of zero or more cues
-
A list of text track cues, along with rules for updating the text track rendering. For example, for WebVTT, the rules for updating the display of WebVTT text tracks. [WEBVTT]
The list of cues of a text track can change dynamically, either because the text track has not yet been loaded or is still loading, or due to DOM manipulation.
Each text track has a corresponding TextTrack
object.
Each media element has a list of pending text tracks, which must initially be empty, a blocked-on-parser flag, which must initially be false, and a did-perform-automatic-track-selection flag, which must also initially be false.
When the user agent is required to populate the list of pending text tracks of a media element, the user agent must add to the element’s list of pending text tracks each text track in the element’s list of text tracks whose text track mode is not disabled and whose text track readiness state is loading.
Whenever a track
element’s parent node changes, the user agent must remove the
corresponding text track from any list of pending text tracks that it is
in.
Whenever a text track’s text track readiness state changes to either loaded or failed to load, the user agent must remove it from any list of pending text tracks that it is in.
When a media element is created by an HTML parser or XML parser, the user agent must set the element’s blocked-on-parser flag to true. When a media element is popped off the stack of open elements of an HTML parser or XML parser, the user agent must honor user preferences for automatic text track selection, populate the list of pending text tracks, and set the element’s blocked-on-parser flag to false.
The text tracks of a media element are ready when both the element’s list of pending text tracks is empty and the element’s blocked-on-parser flag is false.
Each media element has a pending text track change notification flag, which must initially be unset.
Whenever a text track that is in a media element’s list of text tracks has its text track mode change value, the user agent must run the following steps for the media element:
- If the media element’s pending text track change notification flag is set, abort these steps.
- Set the media element’s pending text track change notification flag.
-
Queue a task that runs the following substeps:
- Unset the media element’s pending text track change notification flag.
- Fire a simple event named
change
at the media element’stextTracks
attribute’sTextTrackList
object.
- If the media element’s show poster flag is not set, run the time marches on steps.
The task source for the tasks listed in this section is the DOM manipulation task source.
A text track cue is the unit of time-sensitive data in a text track, corresponding for instance for subtitles and captions to the text that appears at a particular time and disappears at another time.
Each text track cue consists of:
- An identifier
- An arbitrary string.
- A start time
- The time, in seconds and fractions of a second, that describes the beginning of the range of the media data to which the cue applies.
- An end time
- The time, in seconds and fractions of a second, that describes the end of the range of the media data to which the cue applies.
- A pause-on-exit flag
- A boolean indicating whether playback of the media resource is to pause when the end of the range to which the cue applies is reached.
- Some additional format-specific data
- Additional fields, as needed for the format. For example, WebVTT has a text track cue writing direction and so forth. [WEBVTT]
- Rules for extracting the chapter title
- An algorithm which, when applied to the cue, returns a string that can be used in user interfaces that use the cue as a chapter title.
The text track cue start time and text track cue end time can be negative. (The current playback position can never be negative, though, so cues entirely before time zero cannot be active.)
Each text track cue has a corresponding TextTrackCue
object (or more
specifically, an object that inherits from TextTrackCue
— for example, WebVTT
cues use the VTTCue
interface). A text track cue’s in-memory
representation can be dynamically changed through this TextTrackCue
API. [WEBVTT]
A text track cue is associated with rules for updating the text track
rendering, as defined by the specification for the specific kind of text track
cue. These rules are used specifically when the object representing the cue is added to a TextTrack
object using the addCue()
method.
In addition, each text track cue has two pieces of dynamic information:
- The active flag
-
This flag must be initially unset. The flag is used to ensure events are fired appropriately when the cue becomes active or inactive, and to make sure the right cues are rendered.
The user agent must immediately unset this flag whenever the text track cue is removed from its text track’s text track list of cues; whenever the text track itself is removed from its media element’s list of text tracks or has its text track mode changed to disabled; and whenever the media element’s
readyState
is changed back toHAVE_NOTHING
. When the flag is unset in this way for one or more cues in text tracks that were showing prior to the relevant incident, the user agent must, after having unset the flag for all the affected cues, apply the rules for updating the text track rendering of those text tracks. For example, for text tracks based on WebVTT, the rules for updating the display of WebVTT text tracks. [WEBVTT] - The display state
-
This is used as part of the rendering model, to keep cues in a consistent position. It must initially be empty. Whenever the text track cue active flag is unset, the user agent must empty the text track cue display state.
The text track cues of a media element’s text tracks are ordered relative to each other in the text track cue order, which is determined as follows: first group the cues by their text track, with the groups being sorted in the same order as their text tracks appear in the media element’s list of text tracks; then, within each group, cues must be sorted by their start time, earliest first; then, any cues with the same start time must be sorted by their end time, latest first; and finally, any cues with identical end times must be sorted in the order they were last added to their respective text track list of cues, oldest first (so e.g., for cues from a WebVTT file, that would initially be the order in which the cues were listed in the file). [WEBVTT]
4.7.14.11.2. Sourcing in-band text tracks
A media-resource-specific text track is a text track that corresponds to data found in the media resource.
Rules for processing and rendering such data are defined by the relevant specifications, e.g., the specification of the video format if the media resource is a video. Details for some legacy formats can be found in the Sourcing In-band Media Resource Tracks from Media Containers into HTML specification. [INBANDTRACKS]
When a media resource contains data that the user agent recognizes and supports as being equivalent to a text track, the user agent runs the steps to expose a media-resource-specific text track with the relevant data, as follows.
- Associate the relevant data with a new text track and its corresponding new
TextTrack
object. The text track is a media-resource-specific text track. - Set the new text track’s kind, label, and language based on the semantics of the relevant data, as defined for the relevant format [INBANDTRACKS]. If there is no label in that data, then the label must be set to the empty string.
- Associate the text track list of cues with the rules for updating the text track rendering appropriate for the format in question.
-
If the new text track’s kind is
metadata
, then set the text track in-band metadata track dispatch type as follows, based on the type of the media resource:- If the media resource is an Ogg file
- The text track in-band metadata track dispatch type must be set to the value of the Role header field. [OGGSKELETON]
- If the media resource is a WebM file
- The text track in-band metadata track dispatch type must be set to the value
of the
CodecID
element. [WEBM] - If the media resource is an MPEG-2 file
- Let stream type be the value of the "stream_type" field describing the text track’s type in the file’s program map section, interpreted as an 8-bit unsigned integer. Let length be the value of the "ES_info_length" field for the track in the same part of the program map section, interpreted as an integer as defined by the MPEG-2 specification. Let descriptor bytes be the length bytes following the "ES_info_length" field. The text track in-band metadata track dispatch type must be set to the concatenation of the stream type byte and the zero or more descriptor bytes bytes, expressed in hexadecimal using uppercase ASCII hex digits. [MPEG2TS]
- If the media resource is an MPEG-4 file
-
Let the
first
stsd
box of the firststbl
box of the firstminf
box of the firstmdia
box of the text track’strak
box in the firstmoov
box of the file be the stsd box, if any.If the file has no stsd box, or if the stsd box has neither a
mett
box nor ametx
box, then the text track in-band metadata track dispatch type must be set to the empty string.Otherwise, if the stsd box has a
mett
box then the text track in-band metadata track dispatch type must be set to the concatenation of the string "mett
", a U+0020 SPACE character, and the value of the firstmime_format
field of the firstmett
box of the stsd box, or the empty string if that field is absent in that box.Otherwise, if the stsd box has no
mett
box but has ametx
box then the text track in-band metadata track dispatch type must be set to the concatenation of the string "metx
", a U+0020 SPACE character, and the value of the firstnamespace
field of the firstmetx
box of the stsd box, or the empty string if that field is absent in that box. - If the media resource is a DASH media resource
- The text track in-band metadata track dispatch type must be set to the concatenation of the "AdaptationSet" element attributes and all child Role descriptors. [MPEGDASH]
- Populate the new text track’s list of cues with the cues parsed so far, following the guidelines for exposing cues, and begin updating it dynamically as necessary.
- Set the new text track’s readiness state to loaded.
-
Set the new text track’s mode to the
mode consistent with the user’s preferences and the requirements of the relevant specification
for the data.
For instance, if there are no other active subtitles, and this is a forced subtitle track (a subtitle track giving subtitles in the audio track’s primary language, but only for audio that is actually in another language), then those subtitles might be activated here.
- Add the new text track to the media element’s list of text tracks.
- Fire a trusted event with the name
addtrack
, that does not bubble and is not cancelable, and that uses theTrackEvent
interface, with thetrack
attribute initialized to the text track’sTextTrack
object, at the media element’stextTracks
attribute’sTextTrackList
object.
4.7.14.11.3. Sourcing out-of-band text tracks
When a track
element is created, it must be associated with a new text
track (with its value set as defined below) and its corresponding new TextTrack
object.
The text track kind is determined from the state of the element’s kind
attribute according to the following table; for a state given
in a cell of the first column, the kind is the string given
in the second column:
State | String |
---|---|
Subtitles | subtitles
|
Captions | captions
|
Descriptions | descriptions
|
Chapters | chapters
|
Metadata | metadata
|
The text track label is the element’s track label.
The text track language is the element’s track language, if any, or the empty string otherwise.
As the kind
, label
,
and srclang
attributes are set, changed, or removed, the text track must update accordingly, as per the definitions above.
Changes to the track URL are handled in the algorithm below.
The text track readiness state is initially not loaded, and the text track mode is initially disabled.
The text track list of cues is initially empty. It is dynamically modified when the referenced file is parsed. Associated with the list are the rules for updating the text track rendering appropriate for the format in question; for WebVTT, this is the rules for updating the display of WebVTT text tracks. [WEBVTT]
When a track
element’s parent element changes and the new parent is a media element, then the user agent must add the track
element’s corresponding text track to the media element’s list of text tracks, and
then queue a task to fire a trusted event with the name addtrack
, that does not bubble and is not cancelable, and that uses
the TrackEvent
interface, with the track
attribute initialized to the text track’s TextTrack
object, at the media element’s textTracks
attribute’s TextTrackList
object.
When a track
element’s parent element changes and the old parent was a media element, then the user agent must remove the track
element’s corresponding text track from the media element’s list of text tracks,
and then queue a task to fire a trusted event with the name removetrack
, that does not bubble and is not cancelable, and that
uses the TrackEvent
interface, with the track
attribute initialized to the text track’s TextTrack
object, at the media element’s textTracks
attribute’s TextTrackList
object.
When a text track corresponding to a track
element is added to a media element’s list of text tracks, the user agent must queue a
task to run the following steps for the media element:
- If the element’s blocked-on-parser flag is true, abort these steps.
- If the element’s did-perform-automatic-track-selection flag is true, abort these steps.
- Honor user preferences for automatic text track selection for this element.
When the user agent is required to honor user preferences for automatic text track selection for a media element, the user agent must run the following steps:
- Perform automatic text track selection for
subtitles
andcaptions
. - Perform automatic text track selection for
descriptions
. - Perform automatic text track selection for
chapters
. - If there are any text tracks in the media element’s list of text tracks whose text track kind is
metadata
that correspond totrack
elements with adefault
attribute set whose text track mode is set to disabled, then set the text track mode of all such tracks to - Set the element’s did-perform-automatic-track-selection flag to true.
When the steps above say to perform automatic text track selection for one or more text track kinds, it means to run the following steps:
- Let candidates be a list consisting of the text tracks in the media element’s list of text tracks whose text track kind is one of the kinds that were passed to the algorithm, if any, in the order given in the list of text tracks.
- If candidates is empty, then abort these steps.
- If any of the text tracks in candidates have a text track mode set to showing, abort these steps.
-
If the user has expressed an interest in having a track from candidates enabled based on its text track kind, text track language, and text track label, then set its text track mode to showing.
For example, the user could have set a browser preference to the effect of "I want French captions whenever possible", or "If there is a subtitle track with "Commentary" in the title, enable it", or "If there are audio description tracks available, enable one, ideally in Swiss German, but failing that in Standard Swiss German or Standard German".
Otherwise, if there are any text tracks in candidates that correspond to
track
elements with adefault
attribute set whose text track mode is set to disabled, then set the text track mode of the first such track to showing.
When a text track corresponding to a track
element experiences any of
the following circumstances, the user agent must start the track
processing
model for that text track and its track
element:
- The
track
element is created. - The text track has its text track mode changed.
- The
track
element’s parent element changes and the new parent is a media element.
When a user agent is to start the track
processing model for a text track and its track
element, it must run the following algorithm.
This algorithm interacts closely with the event loop mechanism; in particular, it has
a synchronous section (which is triggered as part of the event loop algorithm). The steps in that section are marked with ⌛.
- If another occurrence of this algorithm is already running for this text
track and its
track
element, abort these steps, letting that other algorithm take care of this element. - If the text track’s text track mode is not set to one of or showing, abort these steps.
- If the text track’s
track
element does not have a media element as a parent, abort these steps. - Run the remainder of these steps in parallel, allowing whatever caused these steps to run to continue.
- Top: Await a stable state. The synchronous section consists of the following steps. (The steps in the synchronous section are marked with ⌛.)
- ⌛ Set the text track readiness state to loading.
- ⌛ Let URL be the track URL of the
track
element. - ⌛ If the
track
element’s parent is a media element then let corsAttributeState be the state of the parent media element’scrossorigin
content attribute. Otherwise, let corsAttributeState be No CORS. - End the synchronous section, continuing the remaining steps in parallel.
-
If URL is not the empty string, run these substeps:
- Let request be the result of creating a potential-CORS request given URL, corsAttributeState, and with the same-origin fallback flag set.
- Set request’s client to the
track
element’s node document’sWindow
object’s environment settings object and type to "track
". - Fetch request.
The tasks queued by the fetching algorithm on the networking task source to process the data as it is being fetched must determine the type of the resource. If the type of the resource is not a supported text track format, the load will fail, as described below. Otherwise, the resource’s data must be passed to the appropriate parser (e.g., the WebVTT parser) as it is received, with the text track list of cues being used for that parser’s output. [WEBVTT]
The appropriate parser will incrementally update the text track list of cues during these networking task source tasks, as each such task is run with whatever data has been received from the network).
This specification does not currently say whether or how to check the MIME types of text tracks, or whether or how to perform file type sniffing using the actual file data. Implementors differ in their intentions on this matter and it is therefore unclear what the right solution is. In the absence of any requirement here, the HTTP specification’s strict requirement to follow the Content-Type header prevails ("Content-Type specifies the media type of the underlying data." ... "If and only if the media type is not given by a Content-Type field, the recipient MAY attempt to guess the media type via inspection of its content and/or the name extension(s) of the URI used to identify the resource.").
If the fetching algorithm fails for any reason (network error, the server returns an error code, a cross-origin check fails, etc), or if URL is the empty string, then queue a task to first change the text track readiness state to failed to load and then fire a simple event named
error
at thetrack
element. This task must use the DOM manipulation task source.If the fetching algorithm does not fail, but the type of the resource is not a supported text track format, or the file was not successfully processed (e.g., the format in question is an XML format and the file contained a well-formedness error that the XML specification requires be detected and reported to the application), then the task that is queued by the networking task source in which the aforementioned problem is found must change the text track readiness state to failed to load and fire a simple event named
error
at thetrack
element.If the fetching algorithm does not fail, and the file was successfully processed, then the final task that is queued by the networking task source, after it has finished parsing the data, must change the text track readiness state to loaded, and fire a simple event named
load
at thetrack
element.If, while fetching is ongoing, either:
- the track URL changes so that it is no longer equal to URL, while the text track mode is set to or showing; or
- the text track mode changes to or showing, while the track URL is not equal to URL
...then the user agent must abort fetching, discarding any pending tasks generated by that algorithm (and in particular, not adding any cues to the text track list of cues after the moment the URL changed), and then queue a task that first changes the text track readiness state to failed to load and then fires a simple event named
error
at thetrack
element. This task must use the DOM manipulation task source. - Wait until the text track readiness state is no longer set to loading.
- Wait until the track URL is no longer equal to URL, at the same time as the text track mode is set to or showing.
- Jump to the step labeled top.
Whenever a track
element has its src
attribute
set, changed, or removed, the user agent must immediately empty the element’s text
track’s text track list of cues. (This also causes the algorithm above to stop
adding cues from the resource being obtained using the previously given URL, if any.)
4.7.14.11.4. Guidelines for exposing cues in various formats as text track cues
How a specific format’s text track cues are to be interpreted for the purposes of processing by an HTML user agent is defined by that format [INBANDTRACKS]. In the absence of such a specification, this section provides some constraints within which implementations can attempt to consistently expose such formats.
To support the text track model of HTML, each unit of timed data is converted to a text track cue. Where the mapping of the format’s features to the aspects of a text track cue as defined in this specification are not defined, implementations must ensure that the mapping is consistent with the definitions of the aspects of a text track cue as defined above, as well as with the following constraints:
- The text track cue identifier
- Should be set to the empty string if the format has no obvious analog to a per-cue identifier.
- The text track cue pause-on-exit flag
- Should be set to false.
For media-resource-specific text tracks of kind metadata
, text track cues are exposed using the DataCue
object
unless there is a more appropriate TextTrackCue
interface available.
For example, if the media-resource-specific text track format is WebVTT,
then VTTCue
is more appropriate.
4.7.14.11.5. Text track API
interface TextTrackList : EventTarget { readonly attribute unsigned long length; getter TextTrack (unsigned long index); TextTrack? getTrackById(DOMString id); attribute EventHandler onchange; attribute EventHandler onaddtrack; attribute EventHandler onremovetrack; };
- media .
textTracks
.length
- Returns the number of text tracks associated with the media element (e.g., from
track
elements). This is the number of text tracks in the media element’s list of text tracks. - media .
textTracks[
n]
- Returns the
TextTrack
object representing the nth text track in the media element’s list of text tracks. - textTrack = media .
textTracks
.getTrackById
( id ) -
Returns the
TextTrack
object with the given identifier, or null if no track has that identifier.
A TextTrackList
object represents a dynamically updating list of text tracks in a given order.
The textTracks attribute of media elements must
return a TextTrackList
object representing the TextTrack
objects of the text tracks in the media element’s list of text tracks, in the same order as in the list of text tracks.
The length attribute of a TextTrackList
object must return the number of text tracks in the list represented by the TextTrackList
object.
The supported property indices of a TextTrackList
object at any
instant are the numbers from zero to the number of text tracks in
the list represented by the TextTrackList
object minus one, if any. If there are no text tracks in the list, there are no supported property indices.
To determine the value of an indexed property of a TextTrackList
object for a given index index, the user agent must return the indexth text track in the list represented by the TextTrackList
object.
The getTrackById(id) method must return the
first TextTrack
in the TextTrackList
object whose id IDL
attribute would return a value equal to the value of the id argument. When no tracks
match the given argument, the method must return null.
enum TextTrackMode { "disabled", "hidden", "showing" }; enum TextTrackKind { "subtitles", "captions", "descriptions", "chapters", "metadata" }; interface TextTrack : EventTarget { readonly attribute TextTrackKind kind; readonly attribute DOMString label; readonly attribute DOMString language; readonly attribute DOMString id; readonly attribute DOMString inBandMetadataTrackDispatchType; attribute TextTrackMode mode; readonly attribute TextTrackCueList? cues; readonly attribute TextTrackCueList? activeCues; void addCue(TextTrackCue cue); void removeCue(TextTrackCue cue); attribute EventHandler oncuechange; };
- textTrack = media .
addTextTrack
( kind [, label [, language ] ] ) -
Creates and returns a new
TextTrack
object, which is also added to the media element’s list of text tracks. - textTrack .
kind
-
Returns the text track kind string.
- textTrack .
label
-
Returns the text track label, if there is one, or the empty string otherwise (indicating that a custom label probably needs to be generated from the other attributes of the object if the object is exposed to the user).
- textTrack .
language
- Returns the text track language string.
- textTrack .
id
-
Returns the ID of the given track.
For in-band tracks, this is the ID that can be used with a fragment identifier if the format supports the Media Fragments URI syntax, and that can be used with the
getTrackById()
method. [MEDIA-FRAGS]For
TextTrack
objects corresponding totrack
elements, this is the ID of thetrack
element. - textTrack .
inBandMetadataTrackDispatchType
-
Returns the text track in-band metadata track dispatch type string.
- textTrack .
mode
[ = value ] -
Returns the text track mode, represented by a string from the following list:
- "
disabled
" - The text track disabled mode.
- "
hidden
" - The text track hidden mode.
- "
showing
" - The text track showing mode.
Can be set, to change the mode.
- "
- textTrack .
cues
- Returns the text track list of cues, as a
TextTrackCueList
object. - textTrack .
activeCues
-
Returns the text track cues from the text track list of cues that are currently active (i.e., that start before the current playback position and end after it), as a
TextTrackCueList
object. - textTrack .
addCue
( cue ) - Adds the given cue to textTrack’s text track list of cues.
- textTrack .
removeCue
( cue ) - Removes the given cue from textTrack’s text track list of cues.
The addTextTrack(kind, label, language)
method of media elements, when invoked, must run the following steps:
-
Create a new
TextTrack
object. -
Create a new text track corresponding to the new object, and set its text track kind to kind, its text track label to label, its text track language to language, its text track readiness state to the text track loaded state, its text track mode to the mode, and its text track list of cues to an empty list.
Initially, the text track list of cues is not associated with any rules for updating the text track rendering. When a text track cue is added to it, the text track list of cues has its rules permanently set accordingly.
-
Add the new text track to the media element’s list of text tracks.
-
Queue a task to fire a trusted event with the name
addtrack
, that does not bubble and is not cancelable, and that uses theTrackEvent
interface, with thetrack
attribute initialized to the new text track’sTextTrack
object, at the media element’stextTracks
attribute’sTextTrackList
object. -
Return the new
TextTrack
object.
The kind
attribute must return the text track kind of the text track that the TextTrack
object
represents.
The label
attribute must return the text track label of the text track that the TextTrack
object represents.
The language
attribute must return the text track language of the text track that the TextTrack
object represents.
The id
attribute returns the track’s
identifier, if it has one, or the empty string otherwise. For tracks that correspond to track
elements, the track’s identifier is the value of the element’s id
attribute, if any. For in-band tracks, the track’s identifier is
specified by the media resource. If the media resource is in a format
that supports the Media Fragments URI fragment identifier syntax, the identifier
returned for a particular track must be the same identifier that would enable the track if used as
the name of a track in the track dimension of such a fragment identifier. [MEDIA-FRAGS]
The inBandMetadataTrackDispatchType
attribute must return the text track in-band metadata track dispatch type of the text track that the TextTrack
object represents.
The mode
attribute, on getting, must return
the string corresponding to the text track mode of the text track that
the TextTrack
object represents, as defined by the following list:
- "
disabled
" - The text track disabled mode.
- "
hidden
" - The mode.
- "
showing
" - The text track showing mode.
On setting, if the new value isn’t equal to what the attribute would currently return, the new value must be processed as follows:
- If the new value is "
disabled
" -
Set the text track mode of the text track that the
TextTrack
object represents to the text track disabled mode. - If the new value is "
hidden
" -
Set the text track mode of the text track that the
TextTrack
object represents to the mode. - If the new value is "
showing
" -
Set the text track mode of the text track that the
TextTrack
object represents to the text track showing mode.
If the text track mode of the text track that the TextTrack
object represents is not the text track disabled mode, then
the cues
attribute must return a live TextTrackCueList
object that represents the subset of the text track list of cues of the text track that the TextTrack
object represents whose end
times occur at or after the earliest possible position when the script
started, in text track cue order. Otherwise, it must return null. For each TextTrack
object, when an
object is returned, the same TextTrackCueList
object must be returned each time.
The earliest possible position when the script started is whatever the earliest possible position was the last time the event loop reached step 1.
If the text track mode of the text track that the TextTrack
object represents is not the text track disabled mode, then
the activeCues
attribute must return a live TextTrackCueList
object that represents the subset of the text track list of cues of the text track that the TextTrack
object represents whose active flag was set when the script
started, in text track cue order. Otherwise, it must return null. For each TextTrack
object, when an
object is returned, the same TextTrackCueList
object must be returned each time.
A text track cue’s active flag was set when the script started if its text track cue active flag was set the last time the event loop reached step 1.
The addCue(cue)
method
of TextTrack
objects, when invoked, must run the following steps:
- If the text track list of cues does not yet have any associated rules for updating the text track rendering, then associate the text track list of cues with the rules for updating the text track rendering appropriate to cue.
- If text track list of cues' associated rules for updating the text
track rendering are not the same rules for updating the text track rendering as appropriate for cue, then throw an
InvalidStateError
exception and abort these steps. - If the given cue is in a text track list of cues, then remove cue from that text track list of cues.
- Add cue to the method’s
TextTrack
object’s text track’s text track list of cues.
The removeCue(cue)
method of TextTrack
objects, when invoked, must run the following steps:
- If the given cue is not currently listed in the method’s
TextTrack
object’s text track’s text track list of cues, then throw aNotFoundError
exception and abort these steps. - Remove cue from the method’s
TextTrack
object’s text track’s text track list of cues.
audio
element is used to play a specific sound-effect from a
sound file containing many sound effects. A cue is used to pause the audio, so that it ends
exactly at the end of the clip, even if the browser is busy running some script. If the page had
relied on script to pause the audio, then the start of the next clip might be heard if the
browser was not able to run the script at the exact time specified.
var sfx = new Audio('sfx.wav'); var sounds = sfx.addTextTrack('metadata'); // add sounds we care about function addFX(start, end, name) { var cue = new VTTCue(start, end, ''); cue.id = name; cue.pauseOnExit = true; sounds.addCue(cue); } addFX(12.783, 13.612, 'dog bark'); addFX(13.612, 15.091, 'kitten mew')) function playSound(id) { sfx.currentTime = sounds.getCueById(id).startTime; sfx.play(); } // play a bark as soon as we can sfx.oncanplaythrough = function () { playSound('dog bark'); } // meow when the user tries to leave window.onbeforeunload = function () { playSound('kitten mew'); return 'Are you sure you want to leave this awesome page?'; }
interface TextTrackCueList { readonly attribute unsigned long length; getter TextTrackCue (unsigned long index); TextTrackCue? getCueById(DOMString id); };
- cuelist .
length
- Returns the number of cues in the list.
- cuelist[index]
- Returns the text track cue with index index in the list. The cues are sorted in text track cue order.
- cuelist .
getCueById
( id ) - Returns the first text track cue (in text track cue order) with text track cue identifier id. Returns null if none of the cues have the given identifier or if the argument is the empty string.
A TextTrackCueList
object represents a dynamically updating list of text track cues in a given order.
The length
attribute must return
the number of cues in the list represented by the TextTrackCueList
object.
The supported property indices of a TextTrackCueList
object at any
instant are the numbers from zero to the number of cues in the
list represented by the TextTrackCueList
object minus one, if any. If there are no cues in the list, there are no supported property
indices.
To determine the value of an indexed property for a given index index, the user agent must return the indexth text track
cue in the list represented by the TextTrackCueList
object.
The getCueById(id)
method, when called with an argument other than the empty string,
must return the first text track cue in the list represented by the TextTrackCueList
object whose text track cue identifier is id, if any, or null otherwise. If the argument is the empty string, then the method
must return null.
interface TextTrackCue : EventTarget { readonly attribute TextTrack? track; attribute DOMString id; attribute double startTime; attribute double endTime; attribute boolean pauseOnExit; attribute EventHandler onenter; attribute EventHandler onexit; };
- cue .
track
- Returns the
TextTrack
object to which this text track cue belongs, if any, or null otherwise. - cue .
id
[ = value ] - Returns the text track cue identifier. Can be set.
- cue .
startTime
[ = value ] - Returns the text track cue start time, in seconds. Can be set.
- cue .
endTime
[ = value ] - Returns the text track cue end time, in seconds. Can be set.
- cue .
pauseOnExit
[ = value ] - Returns true if the text track cue pause-on-exit flag is set, false otherwise. Can be set.
The track
attribute, on getting, must
return the TextTrack
object of the text track in whose list of cues the text track cue that the TextTrackCue
object represents finds itself, if any; or null otherwise.
The id
attribute, on getting, must return
the text track cue identifier of the text track cue that the TextTrackCue
object represents. On setting, the text track cue
identifier must be set to the new value.
The startTime
attribute, on
getting, must return the text track cue start time of the text track cue that the TextTrackCue
object represents, in seconds. On setting, the text track
cue start time must be set to the new value, interpreted in seconds; then, if the TextTrackCue
object’s text track cue is in a text track’s list of cues, and that text track is in
a media element’s list of text tracks, and the media element’s show poster flag is not set, then run the time marches on steps for that media element.
The endTime
attribute, on getting,
must return the text track cue end time of the text track cue that the TextTrackCue
object represents, in seconds. On setting, the text track cue end
time must be set to the new value, interpreted in seconds; then, if the TextTrackCue
object’s text track cue is in a text track’s list of cues, and that text track is in
a media element’s list of text tracks, and the media element’s show poster flag is not set, then run the time marches on steps for that media element.
The pauseOnExit
attribute, on
getting, must return true if the text track cue pause-on-exit flag of the text
track cue that the TextTrackCue
object represents is set; or false otherwise.
On setting, the text track cue pause-on-exit flag must be set if the new value is
true, and must be unset otherwise.
4.7.14.11.6. Text tracks exposing in-band metadata
The use of text tracks exposing in-band metadata is "at risk". If testing during the Candidate Recommendation phase does not identify at least two interoperable implementations in current shipping browsers of text tracks exposing in-band metadata this section will be removed from the HTML 5.1 Specification.
Media resources often contain one or more media-resource-specific text tracks containing data that browsers don’t render, but want to expose to script to allow being dealt with.
If the browser is unable to identify a TextTrackCue
interface that is more
appropriate to expose the data in the cues of a media-resource-specific text track,
the DataCue
object is used. [INBANDTRACKS]
[Constructor(double startTime, double endTime, ArrayBuffer data)] interface DataCue : TextTrackCue { attribute ArrayBuffer data; };
- cue = new
DataCue
( [ startTime, endTime, data ] ) - Returns a new
DataCue
object, for use with theaddCue()
method. The startTime argument sets the text track cue start time. The endTime argument sets the text track cue end time. The data argument is copied as the text track cue data. - cue .
data
[ = value ] - Returns the text track cue data in raw unparsed form. Can be set.
The data
attribute, on getting, must
return the raw text track cue data of the text track cue that the TextTrackCue
object represents. On setting, the text track cue data must
be set to the new value.
The user agent will use DataCue
to expose only text track cue objects that belong to a text track that has a text track kind of metadata.
DataCue
has a constructor to allow script to create DataCue
objects in cases where generic metadata needs to be managed for a text track.
The rules for updating the text track rendering for a DataCue
simply
state that there is no rendering, even when the cues are in showing mode and the text track kind is one of subtitles
or captions
or descriptions
or chapters
.
4.7.14.11.7. Text tracks describing chapters
Chapters are segments of a media resource with a given title. Chapters can be nested, in the same way that sections in a document outline can have subsections.
Each text track cue in a text track being used for describing chapters has three key features: the text track cue start time, giving the start time of the chapter, the text track cue end time, giving the end time of the chapter, and the text track rules for extracting the chapter title.
The rules for constructing the chapter tree from a text track are as follows. They produce a potentially nested list of chapters, each of which have a start time, end time, title, and a list of nested chapters. This algorithm discards cues that do not correctly nest within each other, or that are out of order.
- Let list be a copy of the list of cues of the text track being processed.
- Remove from list any text track cue whose text track cue end time is before its text track cue start time.
- Let output be an empty list of chapters, where a chapter is a record consisting of a start time, an end time, a title, and a (potentially empty) list of nested chapters. For the purpose of this algorithm, each chapter also has a parent chapter.
- Let current chapter be a stand-in chapter whose start time is negative infinity, whose end time is positive infinity, and whose list of nested chapters is output. (This is just used to make the algorithm easier to describe.)
- Loop: If list is empty, jump to the step labeled end.
- Let current cue be the first cue in list, and then remove it from list.
- If current cue’s text track cue start time is less than the start time of current chapter, then return to the step labeled loop.
- While current cue’s text track cue start time is greater than or equal to current chapter’s end time, let current chapter be current chapter’s parent chapter.
- If current cue’s text track cue end time is greater than the end time of current chapter, then return to the step labeled loop.
-
Create a new chapter new chapter, whose start time is current cue’s text track cue start time, whose end time is current cue’s text track cue end time, whose title is current cue’s text track cue data interpreted according to its rules for rendering the cue in isolation, and whose list of nested chapters is empty.
- Append new chapter to current chapter’s list of nested chapters, and let current chapter be new chapter’s parent.
- Let current chapter be new chapter.
- Return to the step labeled loop.
- End: Return output.
WEBVTT 00:00:00.000 --> 00:50:00.000 Astrophysics 00:00:00.000 --> 00:10:00.000 Introduction to Astrophysics 00:10:00.000 --> 00:45:00.000 The Solar System 00:00:00.000 --> 00:10:00.000 Coursework Description 00:50:00.000 --> 01:40:00.000 Computational Physics 00:50:00.000 --> 00:55:00.000 Introduction to Programming 00:55:00.000 --> 01:30:00.000 Data Structures 01:30:00.000 --> 01:35:00.000 Answers to Last Exam 01:35:00.000 --> 01:40:00.000 Coursework Description 01:40:00.000 --> 02:30:00.000 General Relativity 01:40:00.000 --> 02:00:00.000 Tensor Algebra 02:00:00.000 --> 02:30:00.000 The General Relativistic Field Equations
4.7.14.11.8. Event handlers for objects of the text track APIs
The following are the event handlers that (and their corresponding event handler event types) must be supported, as event handler IDL
attributes, by all objects implementing the TextTrackList
interface:
Event handler | Event handler event type |
---|---|
onchange
| change
|
onaddtrack
| addtrack
|
onremovetrack
| removetrack
|
The following are the event handlers that (and their corresponding event handler event types) must be supported, as event handler IDL
attributes, by all objects implementing the TextTrack
interface:
Event handler | Event handler event type |
---|---|
oncuechange
| cuechange
|
The following are the event handlers that (and their corresponding event handler event types) must be supported, as event handler IDL
attributes, by all objects implementing the TextTrackCue
interface:
Event handler | Event handler event type |
---|---|
onenter
| enter
|
onexit
| exit
|
4.7.14.11.9. Best practices for metadata text tracks
This section is non-normative.
Text tracks can be used for storing data relating to the media data, for interactive or augmented views.
For example, a page showing a sports broadcast could include information about the current score. Suppose a robotics competition was being streamed live. The image could be overlayed with the scores, as follows:
In order to make the score display render correctly whenever the user seeks to an arbitrary point in the video, the metadata text track cues need to be as long as is appropriate for the score. For example, in the frame above, there would be maybe one cue that lasts the length of the match that gives the match number, one cue that lasts until the blue alliance’s score changes, and one cue that lasts until the red alliance’s score changes. If the video is just a stream of the live event, the time in the bottom right would presumably be automatically derived from the current video time, rather than based on a cue. However, if the video was just the highlights, then that might be given in cues also.
The following shows what fragments of this could look like in a WebVTT file:
WEBVTT ... 05:10:00.000 --> 05:12:15.000 matchtype:qual matchnumber:37 ... 05:11:02.251 --> 05:11:17.198 red:78 05:11:03.672 --> 05:11:54.198 blue:66 05:11:17.198 --> 05:11:25.912 red:80 05:11:25.912 --> 05:11:26.522 red:83 05:11:26.522 --> 05:11:26.982 red:86 05:11:26.982 --> 05:11:27.499 red:89 ...
The key here is to notice that the information is given in cues that span the length of time to which the relevant event applies. If, instead, the scores were given as zero-length (or very brief, nearly zero-length) cues when the score changes, for example saying "red+2" at 05:11:17.198, "red+3" at 05:11:25.912, etc, problems arise: primarily, seeking is much harder to implement, as the script has to walk the entire list of cues to make sure that no notifications have been missed; but also, if the cues are short it’s possible the script will never see that they are active unless it listens to them specifically.
When using cues in this manner, authors are encouraged to use the cuechange
event to update the current annotations. (In
particular, using the timeupdate
event would be less
appropriate as it would require doing work even when the cues haven’t changed, and, more
importantly, would introduce a higher latency between when the metadata cues become active and
when the display is updated, since timeupdate
events
are rate-limited.)
4.7.14.12. User interface
The controls
attribute is a boolean attribute. If present, it indicates that the author has not provided a scripted
controller and would like the user agent to provide its own set of controls.
If the attribute is present, or if scripting is disabled for the media element, then the user agent should expose a user interface to the user. This user interface should include features to begin playback, pause playback, seek to an arbitrary position in the content (if the content supports arbitrary seeking), change the volume, change the display of closed captions or embedded sign-language tracks, select different audio tracks or turn on audio descriptions, and show the media content in manners more suitable to the user (e.g., fullscreen video or in an independent resizable window). Other controls may also be made available.
A user agent may provide controls to affect playback
of the media resource (e.g., play, pause, seeking, track selection, and volume controls), but
such features should not interfere with the page’s normal rendering. For example, such features
could be exposed in the media element’s context menu, platform
media keys, or a remote control. The user agent may implement this simply by exposing a user
interface to the user as described above (as if the controls
attribute
was present).
If the user agent exposes a user interface to
the user by displaying controls over the media element, then the user agent
should suppress any user interaction events while the user agent is interacting with this
interface. (For example, if the user clicks on a video’s playback control, mousedown
events and so forth would not simultaneously be fired at
elements on the page.)
Where possible (specifically, for starting, stopping, pausing, and unpausing playback, for seeking, for changing the rate of playback, for fast-forwarding or rewinding, for listing, enabling, and disabling text tracks, and for muting or changing the volume of the audio), user interface features exposed by the user agent must be implemented in terms of the DOM API described above, so that, e.g., all the same events fire.
For the purposes of listing chapters in the media resource, only text tracks in the media element’s list of text tracks that are showing and whose text track kind is chapters
should be used. Such tracks must be
interpreted according to the rules for constructing the chapter tree from a text
track. When seeking in response to a user manipulating a chapter selection interface, user
agents should not use the approximate-for-speed flag.
The controls
IDL attribute must reflect the content attribute of the same name.
- media .
volume
[ = value ] -
Returns the current playback volume, as a number in the range 0.0 to 1.0, where 0.0 is the quietest and 1.0 the loudest.
Can be set, to change the volume.
Throws an
IndexSizeError
exception if the new value is not in the range 0.0 .. 1.0. - media .
muted
[ = value ] -
Returns true if audio is muted, overriding the
volume
attribute, and false if thevolume
attribute is being honored.Can be set, to change whether the audio is muted or not.
A media element has a playback volume, which is a fraction in the range 0.0 (silent) to 1.0 (loudest). Initially, the volume should be 1.0, but user agents may remember the last set value across sessions, on a per-site basis or otherwise, so the volume may start at other values.
The volume
IDL attribute must return the playback volume of any audio portions of the media element. On setting, if the new value is in the range 0.0 to 1.0 inclusive, the media element’s playback volume must be
set to the new value. If the new value is outside the range 0.0 to 1.0 inclusive, then, on
setting, an IndexSizeError
exception must be thrown instead.
A media element can also be muted. If anything is muting the element, then it is muted. (For example, when the direction of playback is backwards, the element is muted.)
The muted
IDL attribute must return the value
to which it was last set. When a media element is created, if the element has a muted
content attribute specified, then the muted
IDL attribute should be set to true; otherwise, the user
agents may set the value to the user’s preferred value (e.g., remembering the last set value across
sessions, on a per-site basis or otherwise). While the muted
IDL attribute is set to true, the media element must be muted.
Whenever either of the values that would be returned by the volume
and muted
IDL
attributes change, the user agent must queue a task to fire a simple
event named volumechange
at the media element.
An element’s effective media volume is determined as follows:
- If the user has indicated that the user agent is to override the volume of the element, then the element’s effective media volume is the volume desired by the user. Abort these steps.
- If the element’s audio output is muted, the element’s effective media volume is zero. Abort these steps.
- Let volume be the playback volume of the audio portions of the media element, in range 0.0 (silent) to 1.0 (loudest).
- The element’s effective media volume is volume, interpreted relative to the range 0.0 to 1.0, with 0.0 being silent, and 1.0 being the loudest setting, values in between increasing in loudness. The range need not be linear. The loudest setting may be lower than the system’s loudest possible setting; for example the user could have set a maximum volume.
The muted
content attribute on media elements is a boolean attribute that controls the
default state of the audio output of the media resource, potentially overriding user
preferences.
This attribute has no dynamic effect (it only controls the default state of the element).
<video src="adverts.cgi?kind=video" controls autoplay loop muted></video>
4.7.14.13. Time ranges
Objects implementing the TimeRanges
interface
represent a list of ranges (periods) of time.
interface TimeRanges { readonly attribute unsigned long length; double start(unsigned long index); double end(unsigned long index); };
- media .
length
-
Returns the number of ranges in the object.
- time = media .
start
(index) -
Returns the time for the start of the range with the given index.
Throws an
IndexSizeError
exception if the index is out of range. - time = media .
end
(index) -
Returns the time for the end of the range with the given index.
Throws an
IndexSizeError
exception if the index is out of range.
The length
IDL attribute must return the
number of ranges represented by the object.
The start(index)
method must return the position of the start of the indexth range represented
by the object, in seconds measured from the start of the timeline that the object covers.
The end(index)
method
must return the position of the end of the indexth range represented by the
object, in seconds measured from the start of the timeline that the object covers.
These methods must throw IndexSizeError
exceptions if called with an index argument greater than or equal to the number of ranges represented by the
object.
When a TimeRanges
object is said to be a normalized TimeRanges
object, the ranges it represents must obey the following criteria:
- The start of a range must be greater than the end of all earlier ranges.
- The start of a range must be less than or equal to the end of that same range.
In other words, the ranges in such an object are ordered, don’t overlap, and don’t touch (adjacent ranges are folded into one bigger range). A range can be empty (referencing just a single moment in time), e.g., to indicate that only one frame is currently buffered in the case that the user agent has discarded the entire media resource except for the current frame, when a media element is paused.
Ranges in a TimeRanges
object must be inclusive.
Thus, the end of a range would be equal to the start of a following adjacent (touching but not overlapping) range. Similarly, a range covering a whole timeline anchored at zero would have a start equal to zero and an end equal to the duration of the timeline.
The timelines used by the objects returned by the buffered
, seekable
and played
IDL attributes of media elements must be that element’s media timeline.
4.7.14.14. The TrackEvent
interface
[Constructor(DOMString type, optional TrackEventInit eventInitDict)] interface TrackEvent : Event { readonly attribute (VideoTrack or AudioTrack or TextTrack)? track; }; dictionary TrackEventInit : EventInit { (VideoTrack or AudioTrack or TextTrack)? track; };
- event .
track
-
Returns the track object (
TextTrack
,AudioTrack
, orVideoTrack
) to which the event relates.
The track
attribute must return the value
it was initialized to. When the object is created, this attribute must be initialized to null. It
represents the context information for the event.
4.7.14.15. Event summary
This section is non-normative.
The following events fire on media elements as part of the processing model described above:
Event name | Interface | Fired when... | Preconditions |
---|---|---|---|
loadstart
| Event
| The user agent begins looking for media data, as part of the resource selection algorithm. | networkState equals NETWORK_LOADING
|
progress
| Event
| The user agent is fetching media data. | networkState equals NETWORK_LOADING
|
suspend
| Event
| The user agent is intentionally not currently fetching media data. | networkState equals NETWORK_IDLE
|
abort
| Event
| The user agent stops fetching the media data before it is completely downloaded, but not due to an error. | error is an object with the code MEDIA_ERR_ABORTED . networkState equals either NETWORK_EMPTY or NETWORK_IDLE , depending on when the download was aborted.
|
error
| Event
| An error occurs while fetching the media data or the type of the resource is not supported media format. | error is an object with the code MEDIA_ERR_NETWORK or higher. networkState equals either NETWORK_EMPTY or NETWORK_IDLE , depending on when the download was aborted.
|
emptied
| Event
| A media element whose networkState was previously not in the NETWORK_EMPTY state has
just switched to that state (either because of a fatal error during load that’s about to be
reported, or because the load() method was invoked while
the resource selection algorithm was already
running).
| networkState is NETWORK_EMPTY ; all the IDL attributes are in their
initial states.
|
stalled
| Event
| The user agent is trying to fetch media data, but data is unexpectedly not forthcoming. | networkState is NETWORK_LOADING .
|
loadedmetadata
| Event
| The user agent has just determined the duration and dimensions of the media resource and the text tracks are ready. | readyState is newly equal to HAVE_METADATA or greater for the first time.
|
loadeddata
| Event
| The user agent can render the media data at the current playback position for the first time. | readyState newly increased to HAVE_CURRENT_DATA or greater for the first time.
|
canplay
| Event
| The user agent can resume playback of the media data, but estimates that if playback were to be started now, the media resource could not be rendered at the current playback rate up to its end without having to stop for further buffering of content. | readyState newly increased to HAVE_FUTURE_DATA or greater.
|
canplaythrough
| Event
| The user agent estimates that if playback were to be started now, the media resource could be rendered at the current playback rate all the way to its end without having to stop for further buffering. | readyState is newly equal to HAVE_ENOUGH_DATA .
|
playing
| Event
| Playback is ready to start after having been paused or delayed due to lack of media data. | readyState is newly equal to or greater than HAVE_FUTURE_DATA and paused is false, or paused is newly false and readyState is equal to or greater than HAVE_FUTURE_DATA . Even if this event fires, the
element might still not be potentially playing, e.g., if the element is paused for user interaction or paused for in-band content.
|
waiting
| Event
| Playback has stopped because the next frame is not available, but the user agent expects that frame to become available in due course. | readyState is equal to or less than HAVE_CURRENT_DATA , and paused is false. Either seeking is true, or the current playback position is not contained in any of the ranges in buffered . It
is possible for playback to stop for other reasons without paused being false, but those reasons do not fire this event
(and when those situations resolve, a separate playing event is not fired either): e.g., the playback ended, or playback stopped due to errors, or the element has paused for user interaction or paused for in-band content.
|
seeking
| Event
| The seeking IDL attribute changed to true, and the user agent has started seeking to a new position.
| |
seeked
| Event
| The seeking IDL attribute changed to false after the current playback position was changed.
| |
ended
| Event
| Playback has stopped because the end of the media resource was reached. | currentTime equals the end of the media
resource; ended is true.
|
durationchange
| Event
| The duration attribute has just been updated.
| |
timeupdate
| Event
| The current playback position changed as part of normal playback or in an especially interesting way, for example discontinuously. | |
play
| Event
| The element is no longer paused. Fired after the play() method has returned, or when the autoplay attribute
has caused playback to begin.
| paused is newly false.
|
pause
| Event
| The element has been paused. Fired after the pause() method has returned.
| paused is newly true.
|
ratechange
| Event
| Either the defaultPlaybackRate or the playbackRate attribute has just been updated.
| |
resize
| Event
| One or both of the videoWidth and videoHeight attributes have just been updated.
| Media element is a video element; readyState is not HAVE_NOTHING
|
volumechange
| Event
| Either the volume attribute or the muted attribute has changed. Fired after the relevant
attribute’s setter has returned.
|
The following event fires on source
element:
Event name | Interface | Fired when... |
---|---|---|
error
| Event
| An error occurs while fetching the media data or the type of the resource is not supported media format. |
The following events fire on AudioTrackList
, VideoTrackList
, and TextTrackList
objects:
Event name | Interface | Fired when... |
---|---|---|
change
| Event
| One or more tracks in the track list have been enabled or disabled. |
addtrack
| TrackEvent
| A track has been added to the track list. |
removetrack
| TrackEvent
| A track has been removed from the track list. |
The following event fires on TextTrack
objects and track
elements:
Event name | Interface | Fired when... |
---|---|---|
cuechange
| Event
| One or more cues in the track have become active or stopped being active. |
The following events fire on track
elements:
The following events fire on TextTrackCue
objects:
Event name | Interface | Fired when... |
---|---|---|
enter
| Event
| The cue has become active. |
exit
| Event
| The cue has stopped being active. |
4.7.14.16. Security and privacy considerations
The main security and privacy implications of the video
and audio
elements come from the ability to embed media cross-origin. There are two directions that threats
can flow: from hostile content to a victim page, and from a hostile page to victim content.
If a victim page embeds hostile content, the threat is that the content might contain scripted
code that attempts to interact with the Document
that embeds the content. To avoid
this, user agents must ensure that there is no access from the content to the embedding page. In
the case of media content that uses DOM concepts, the embedded content must be treated as if it
was in its own unrelated top-level browsing context.
For instance, if an SVG animation was embedded in a video
element,
the user agent would not give it access to the DOM of the outer page. From the perspective of
scripts in the SVG resource, the SVG file would appear to be in a lone top-level browsing context
with no parent.
If a hostile page embeds victim content, the threat is that the embedding page could obtain
information from the content that it would not otherwise have access to. The API does expose some
information: the existence of the media, its type, its duration, its size, and the performance
characteristics of its host. Such information is already potentially problematic, but in practice
the same information can be obtained using the img
element, and so it has been deemed
acceptable.
However, significantly more sensitive information could be obtained if the user agent further
exposes metadata within the content such as subtitles or chapter titles. Such information is
therefore only exposed if the video resource passes a CORS resource sharing check.
The crossorigin
attribute allows authors to control
how this check is performed. [FETCH]
Without this restriction, an attacker could trick a user running within a corporate network into visiting a site that attempts to load a video from a previously leaked location on the corporation’s intranet. If such a video included confidential plans for a new product, then being able to read the subtitles would present a serious confidentiality breach.
4.7.14.17. Best practices for authors using media elements
This section is non-normative.
Playing audio and video resources on small devices such as set-top boxes or mobile phones is
often constrained by limited hardware resources in the device. For example, a device might only
support three simultaneous videos. For this reason, it is a good practice to release resources
held by media elements when they are done playing, either by
being very careful about removing all references to the element and allowing it to be garbage
collected, or, even better, by removing the element’s src
attribute and any source
element descendants, and invoking the element’s load()
method.
Similarly, when the playback rate is not exactly 1.0, hardware, software, or format limitations can cause video frames to be dropped and audio to be choppy or muted.
4.7.14.18. Best practices for implementors of media elements
This section is non-normative.
How accurately various aspects of the media element API are implemented is considered a quality-of-implementation issue.
For example, when implementing the buffered
attribute,
how precise an implementation reports the ranges that have been buffered depends on how carefully
the user agent inspects the data. Since the API reports ranges as times, but the data is obtained
in byte streams, a user agent receiving a variable-bit-rate stream might only be able to determine
precise times by actually decoding all of the data. User agents aren’t required to do this,
however; they can instead return estimates (e.g., based on the average bitrate seen so far) which
get revised as more information becomes available.
As a general rule, user agents are urged to be conservative rather than optimistic. For example, it would be bad to report that everything had been buffered when it had not.
Another quality-of-implementation issue would be playing a video backwards when the codec is designed only for forward playback (e.g., there aren’t many key frames, and they are far apart, and the intervening frames only have deltas from the previous frame). User agents could do a poor job, e.g., only showing key frames; however, better implementations would do more work and thus do a better job, e.g., actually decoding parts of the video forwards, storing the complete frames, and then playing the frames backwards.
Similarly, while implementations are allowed to drop buffered data at any time (there is no requirement that a user agent keep all the media data obtained for the lifetime of the media element), it is again a quality of implementation issue: user agents with sufficient resources to keep all the data around are encouraged to do so, as this allows for a better user experience. For example, if the user is watching a live stream, a user agent could allow the user only to view the live video; however, a better user agent would buffer everything and allow the user to seek through the earlier material, pause it, play it forwards and backwards, etc.
When a media element that is paused is removed from a document and not reinserted before the next time the event loop reaches step 1, implementations that are resource constrained are encouraged to take that opportunity to release all hardware resources (like video planes, networking resources, and data buffers) used by the media element. (User agents still have to keep track of the playback position and so forth, though, in case playback is later restarted.)
4.7.15. The map
element
- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Transparent.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
name
- Name of image map to reference from theusemap
attribute - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLMapElement : HTMLElement { attribute DOMString name; [SameObject] readonly attribute HTMLCollection areas; [SameObject] readonly attribute HTMLCollection images; };
The map
element, in conjunction with an img
element and any area
element descendants, defines an image map. The element represents its children.
The name
attribute gives the map a name so that
it can be referenced. The attribute must be present and must have a non-empty value with no space characters. The value of the name
attribute must not be a compatibility caseless match for the value of the name
attribute of another map
element in the same
document. If the id
attribute is also specified, both attributes must
have the same value.
- map .
areas
- map .
images
-
Returns an
HTMLCollection
of theimg
andobject
elements that use themap
.
The areas
attribute must return an HTMLCollection
rooted at the map
element, whose filter matches only area
elements.
The images
attribute must return an HTMLCollection
rooted at the Document
node, whose filter matches only img
and object
elements that are associated with this map
element according to the image map processing model.
The IDL attribute name
must reflect the content attribute of the same name.
<!DOCTYPE HTML> <TITLE>Babies™: Toys</TITLE> <HEADER> <h1>Toys</h1> <IMG SRC="/images/menu.gif" ALT="Babies™ navigation menu. Select a department to go to its page." USEMAP="#NAV"> </HEADER> ... <FOOTER> <MAP NAME="NAV"> <P> <A HREF="/clothes/">Clothes</A> <AREA ALT="Clothes" COORDS="0,0,100,50" HREF="/clothes/"> | <A HREF="/toys/">Toys</A> <AREA ALT="Toys" COORDS="100,0,200,50" HREF="/toys/"> | <A HREF="/food/">Food</A> <AREA ALT="Food" COORDS="200,0,300,50" HREF="/food/"> | <A HREF="/books/">Books</A> <AREA ALT="Books" COORDS="300,0,400,50" HREF="/books/"> </P> </MAP> </FOOTER>
4.7.16. The area
element
- Categories:
- Flow content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected, but only if there is a
map
element ancestor or atemplate
element ancestor. - Content model:
- Nothing.
- Tag omission in text/html:
- No end tag
- Content attributes:
- Global attributes
alt
- Replacement text for use when images are not availablecoords
- Coordinates for the shape to be created in an image mapdownload
- Whether to download the resource instead of navigating to it, and its file name if sohref
- Address of the hyperlinkhreflang
- Language of the linked resourcerel
- Relationship of this document (or subsection/topic) to the destination resourceshape
- The kind of shape to be created in an image maptarget
- browsing context for hyperlink navigationtype
- Hint for the type of the referenced resource - Allowed ARIA role attribute values:
link
role (default - do not set).- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLAreaElement : HTMLElement { attribute DOMString alt; attribute DOMString coords; attribute DOMString shape; attribute DOMString target; attribute DOMString download; attribute DOMString rel; readonly attribute DOMTokenList relList; attribute DOMString hreflang; attribute DOMString type; }; HTMLAreaElement implements HTMLHyperlinkElementUtils;
The area
element represents either a hyperlink with some text and a
corresponding area on an image map, or a dead area on an image map.
An area
element with a parent node must have a map
element ancestor
or a template
element ancestor.
If the area
element has an href
attribute, then the area
element represents a hyperlink. In this case,
the alt
attribute must be present. It specifies the
text of the hyperlink. Its value must be text that informs the user about the destination of the link.
If the area
element has no href
attribute, then the area represented by the element cannot be selected, and the alt
attribute must be omitted.
In both cases, the shape
and coords
attributes specify the area.
The shape
attribute is an enumerated
attribute. The following table lists the keywords defined for this attribute. The states
given in the first cell of the rows with keywords give the states to which those keywords map. Some of the keywords are non-conforming, as noted in the last
column.
State | Keywords | Notes |
---|---|---|
Circle state | circle
| |
circ
| Non-conforming | |
Default state | default
| |
Polygon state | poly
| |
polygon
| Non-conforming | |
Rectangle state | rect
| |
rectangle
| Non-conforming |
The attribute may be omitted. The missing value default is the rectangle state.
The coords
attribute must, if specified,
contain a valid list of floating-point numbers. This attribute gives the coordinates for the shape
described by the shape
attribute. The
processing for this attribute is described as part of the image map processing
model.
In the circle state, area
elements must
have a coords
attribute present, with three integers, the
last of which must be non-negative. The first integer must be the distance in CSS pixels from the
left edge of the image to the center of the circle, the second integer must be the distance in CSS
pixels from the top edge of the image to the center of the circle, and the third integer must be
the radius of the circle, again in CSS pixels.
In the default state state, area
elements must not have a coords
attribute. (The area is the
whole image.)
In the polygon state, area
elements must
have a coords
attribute with at least six integers, and the
number of integers must be even. Each pair of integers must represent a coordinate given as the
distances from the left and the top of the image in CSS pixels respectively, and all the
coordinates together must represent the points of the polygon, in order.
In the rectangle state, area
elements must
have a coords
attribute with exactly four integers, the
first of which must be less than the third, and the second of which must be less than the fourth.
The four points must represent, respectively, the distance from the left edge of the image to the
left side of the rectangle, the distance from the top edge to the top side, the distance from the
left edge to the right side, and the distance from the top edge to the bottom side, all in CSS
pixels.
When user agents allow users to follow hyperlinks or download hyperlinks created using the area
element, as described in the next section, the href
, target
,
and download
attributes decide how the link is followed. The rel
, hreflang
, and type
attributes may be used to indicate to the user the
likely nature of the target resource before the user follows the link.
The target
, download
, rel
, hreflang
, and type
attributes must be omitted if the href
attribute is not present.
The activation behavior of area
elements is to run the following
steps:
- If the
area
element’s node document is not fully active, then abort these steps. -
If the
area
element has adownload
attribute and the algorithm is not allowed to show a popup; or, if the user has not indicated a specific browsing context for following the link, and the element’starget
attribute is present, and applying the rules for choosing a browsing context given a browsing context name, using the value of thetarget
attribute as the browsing context name, would result in there not being a chosen browsing context, then run these substeps:- If there is an entry settings object, throw an
InvalidAccessError
exception. - Abort these steps without following the hyperlink.
- If there is an entry settings object, throw an
- Otherwise, the user agent must follow the
hyperlink or download the hyperlink created
by the
area
element, if any, and as determined by thedownload
attribute and any expressed user preference.
The IDL attributes alt
, coords
, target
, download
, rel
, hreflang
, and type
, each must reflect the respective
content attributes of the same name.
The IDL attribute shape
must reflect the shape
content attribute.
The IDL attribute relList
must reflect the rel
content attribute.
The area
element also supports the HTMLHyperlinkElementUtils
interface. [URL]
When the element is created, and whenever the element’s href
content attribute is set, changed, or removed, the user
agent must invoke the element’s HTMLHyperlinkElementUtils
interface’s set the input algorithm with the value of the href
content attribute, if any, or the empty string otherwise,
as the given value.
The element’s HTMLHyperlinkElementUtils
interface’s get the base algorithm must simply return the document base URL.
The element’s HTMLHyperlinkElementUtils
interface’s query encoding is the document’s character encoding.
When the element’s HTMLHyperlinkElementUtils
interface invokes its update steps with a string value, the user
agent must set the element’s href
content attribute to
the string value.
4.7.17. Image maps
An image map allows geometric areas on an image to be associated with hyperlinks.
An image, in the form of an img
element, may be associated with an image map (in the form of a map
element) by specifying a usemap
attribute on
the img
element. The usemap
attribute, if specified, must be a valid
hash-name reference to a map
element.
If we wanted just the colored areas to be clickable, we could do it as follows:
<p> Please select a shape: <img src="shapes.png" usemap="#shapes" alt="Four shapes are available: a red hollow box, a green circle, a blue triangle, and a yellow four-pointed star."> <map name="shapes"> <area shape=rect coords="50,50,100,100"> <!-- the hole in the red box --> <area shape=rect coords="25,25,125,125" href="red.html" alt="Red box."> <area shape=circle coords="200,75,50" href="green.html" alt="Green circle."> <area shape=poly coords="325,25,262,125,388,125" href="blue.html" alt="Blue triangle."> <area shape=poly coords="450,25,435,60,400,75,435,90,450,125,465,90,500,75,465,60" href="yellow.html" alt="Yellow star."> </map> </p>
4.7.17.2. Processing model
If an img
element has a usemap
attribute specified, user agents must process it
as follows:
- Parse the attribute’s value using the rules for parsing a hash-name reference to a
map
element, with the element’s node document as the context node. This will return either an element (the map) or null. - If that returned null, then abort these steps. The image is not associated with an image map after all.
- Otherwise, the user agent must collect all the
area
elements that are descendants of the map. Let those be the areas.
Having obtained the list of area
elements that form the image map (the areas), interactive user agents must process the list in one of two ways.
If the user agent intends to show the text that the img
element represents, then
it must use the following steps.
In user agents that do not support images, or that have images disabled, object
elements cannot represent images, and thus this section never applies (the fallback content is shown instead). The following steps therefore only apply to img
elements.
- Remove all the
area
elements in areas that have nohref
attribute. - Remove all the
area
elements in areas that have noalt
attribute, or whosealt
attribute’s value is the empty string, if there is anotherarea
element in areas with the same value in thehref
attribute and with a non-emptyalt
attribute. -
Each remaining
area
element in areas represents a hyperlink. Those hyperlinks should all be made available to the user in a manner associated with the text of theimg
.In this context, user agents may represent
area
andimg
elements with no specifiedalt
attributes, or whosealt
attributes are the empty string or some other non-visible text, in a user-agent-defined fashion intended to indicate the lack of suitable author-provided text.
If the user agent intends to show the image and allow interaction with the image to select
hyperlinks, then the image must be associated with a set of layered shapes, taken from the area
elements in areas, in reverse tree order (so the last
specified area
element in the map is the bottom-most shape, and
the first element in the map, in tree order, is the top-most shape).
Each area
element in areas must be processed as follows to
obtain a shape to layer onto the image:
- Find the state that the element’s
shape
attribute represents. - Use the rules for parsing a list of floating-point numbers to parse the element’s
coords
attribute, if it is present, and let the result be the coords list. If the attribute is absent, let the coords list be the empty list. -
If the number of items in the coords list is less than the minimum number given for the
area
element’s current state, as per the following table, then the shape is empty; abort these steps.State Minimum number of items Circle state 3 Default state 0 Polygon state 6 Rectangle state 4 -
Check for excess items in the coords list as per the entry in the following list corresponding to the
shape
attribute’s state:- Circle state
- Drop any items in the list beyond the third.
- Default state
- Drop all items in the list.
- Polygon state
- Drop the last item if there’s an odd number of items.
- Rectangle state
- Drop any items in the list beyond the fourth.
- If the
shape
attribute represents the rectangle state, and the first number in the list is numerically greater than the third number in the list, then swap those two numbers around. - If the
shape
attribute represents the rectangle state, and the second number in the list is numerically greater than the fourth number in the list, then swap those two numbers around. - If the
shape
attribute represents the circle state, and the third number in the list is less than or equal to zero, then the shape is empty; abort these steps. -
Now, the shape represented by the element is the one described for the entry in the list
below corresponding to the state of the
shape
attribute:- Circle state
-
Let x be the first number in coords, y be the second number, and r be the third number.
The shape is a circle whose center is x CSS pixels from the left edge of the image and y CSS pixels from the top edge of the image, and whose radius is r pixels.
- Default state
-
The shape is a rectangle that exactly covers the entire image.
- Polygon state
-
Let xi be the (2i)th entry in coords, and yi be the (2i+1)th entry in coords (the first entry in coords being the one with index 0).
Let the coordinates be (xi, yi), interpreted in CSS pixels measured from the top left of the image, for all integer values of i from 0 to (N/2)-1, where N is the number of items in coords.
The shape is a polygon whose vertices are given by the coordinates, and whose interior is established using the even-odd rule. [GRAPHICS]
- Rectangle state
-
Let x1 be the first number in coords, y1 be the second number, x2 be the third number, and y2 be the fourth number.
The shape is a rectangle whose top-left corner is given by the coordinate (x1, y1) and whose bottom right corner is given by the coordinate (x2, y2), those coordinates being interpreted as CSS pixels from the top left corner of the image.
For historical reasons, the coordinates must be interpreted relative to the displayed image after any stretching caused by the CSS width and height properties (or, for non-CSS browsers, the image element’s
width
andheight
attributes — CSS browsers map those attributes to the aforementioned CSS properties).Browser zoom features and transforms applied using CSS or SVG do not affect the coordinates.
Pointing device interaction with an image associated with a set of layered shapes per the above
algorithm must result in the relevant user interaction events being first fired to the top-most
shape covering the point that the pointing device indicated, if any, or to the image element
itself, if there is no shape covering that point. User agents may also allow individual area
elements representing hyperlinks to be selected
and activated (e.g., using a keyboard).
Because a map
element (and its area
elements) can be
associated with multiple img
and object
elements, it is possible for an area
element to correspond to multiple focusable areas of the document.
Image maps are live; if the DOM is mutated, then the user agent must act as if it had rerun the algorithms for image maps.
4.7.18. MathML
The math
element from the MathML namespace falls into the embedded content, phrasing content, flow
content, and palpable content categories for the purposes of the content
models in this specification.
This specification refers to several specific MathML elements, in particular: annotation-xml
, merror
, mi
, mn
, mo
, ms
, and mtext
.
When the MathML annotation-xml
element contains
elements from the HTML namespace, such elements must all be flow
content. [MATHML]
When the MathML token elements (mi
, mo
, mn
, ms
,
and mtext
) are descendants of HTML elements, they may contain phrasing content elements from the HTML namespace. [MATHML]
User agents must handle text other than inter-element whitespace found in MathML
elements whose content models do not allow straight text by pretending for the purposes of MathML
content models, layout, and rendering that the text is actually wrapped in an mtext
element in the MathML namespace. (Such text is not,
however, conforming.)
User agents must act as if any MathML element whose contents does not match the element’s
content model was replaced, for the purposes of MathML layout and rendering, by an merror
element in the MathML namespace containing some
appropriate error message.
To enable authors to use MathML tools that only accept MathML in its XML form, interactive HTML user agents are encouraged to provide a way to export any MathML fragment as an XML namespace-well-formed XML fragment.
The semantics of MathML elements are defined by the MathML specification and other applicable specifications. [MATHML]
<!DOCTYPE html> <html> <head> <title>The quadratic formula</title> </head> <body> <h1>The quadratic formula</h1> <p> <math> <mi>x</mi> <mo>=</mo> <mfrac> <mrow> <mo form="prefix">-</mo> <mi>b</mi> <mo>±</mo> <msqrt> <msup> <mi>b</mi> <mn>2</mn> </msup> <mo>-</mo> <mn>4</mn> <mo></mo> <mi>a</mi> <mo></mo> <mi>c</mi> </msqrt> </mrow> <mrow> <mn>2</mn> <mo></mo> <mi>a</mi> </mrow> </mfrac> </math> </p> </body> </html>
4.7.19. SVG
The svg
element from the SVG namespace falls into the embedded content, phrasing content, flow content,
and palpable content categories for the purposes of the content models in this
specification.
To enable authors to use SVG tools that only accept SVG in its XML form, interactive HTML user agents are encouraged to provide a way to export any SVG fragment as an XML namespace-well-formed XML fragment.
When the SVG foreignObject
element contains elements from the HTML namespace, such
elements must all be flow content. [SVG11]
The content model for title elements in the SVG namespace inside HTML documents is phrasing content. (This further constrains the requirements given in the SVG specification.)
The semantics of SVG elements are defined by the SVG specification and other applicable specifications. [SVG11]
User agent requirements: SVG as implemented today follows neither SVG 1.1 nor SVG Tiny 1.2 precisely, instead implementing subsets of each. Although it is hoped that the in-progress SVG 2 specification is a more realistic target for implementations, until that specification is ready, user agents must implement the SVG 1.1 specification with the following willful violations and additions. [SVG11] [SVGTiny12] [SVG2]
The following features from SVG 1.1 must not be implemented:
- The
tref
element - The
cursor
element (use CSS’scursor
property instead) - The font-defining elements:
font
,glyph
,missing-glyph
,hkern
,vkern
,font-face
,font-face-src
,font-face-uri
,font-face-format
, andfont-face-name
(use CSS’s@font-face
instead) - The
externalResourcesRequired
attribute - The
enable-background
property - The
contentScriptType
andcontentStyleType
attributes (use thetype
attribute on thescript
andstyle
elements instead)
The following features from SVG Tiny 1.2 must be implemented:
- The
non-scaling-stroke
value for thevector-effect
property - The
class
attribute is allowed on all SVG elements - The
tabindex
attribute is allowed on visible SVG elements - The ARIA accessibility attributes are allowed on all SVG elements
4.7.20. Dimension attributes
Author requirements: The width
and height
attributes on img
, iframe
, embed
, object
, video
, and, when their type
attribute is in the image button state, input
elements may be
specified to give the dimensions of the visual content of the element (the width and height
respectively, relative to the nominal direction of the output medium), in CSS pixels. The
attributes, if specified, must have values that are valid non-negative integers.
The specified dimensions given may differ from the dimensions specified in the resource itself, since the resource may have a resolution that differs from the CSS pixel resolution. (On screens, CSS pixels have a resolution of 96ppi, but in general the CSS pixel resolution depends on the reading distance.) If both attributes are specified, then one of the following statements must be true:
- specified width - 0.5 ≤ specified height * target ratio ≤ specified width + 0.5
- specified height - 0.5 ≤ specified width / target ratio ≤ specified height + 0.5
- specified height = specified width = 0
The target ratio is the ratio of the intrinsic width to the intrinsic height in the resource. The specified width and specified
height are the values of the width
and height
attributes respectively.
The two attributes must be omitted if the resource in question does not have both an intrinsic width and an intrinsic height.
If the two attributes are both zero, it indicates that the element is not intended for the user (e.g., it might be a part of a service to count page views).
The dimension attributes are not intended to be used to stretch the image.
User agent requirements: User agents are expected to use these attributes as hints for the rendering.
The width
and height
IDL attributes on the iframe
, embed
, object
, and video
elements must reflect the respective content attributes of the same name.
For iframe
, embed
, and object
the IDL
attributes are DOMString
; for video
the IDL attributes are unsigned long
.
The corresponding IDL attributes for img
and input
elements are defined in those respective elements'
sections, as they are slightly more specific to those elements' other behaviors.
4.8. Links
4.8.1. Introduction
Links are a conceptual construct, created by a
, area
, and link
elements, that represent a connection between
two resources, one of which is the current Document
. There are two kinds of links in
HTML:
- Links to external resources
- These are links to resources that are to be used to augment the current document, generally automatically processed by the user agent.
- Hyperlinks
- These are links to other resources that are generally exposed to the user by the user agent so that the user can cause the user agent to navigate to those resources, e.g., to visit them in a browser or download them.
For link
elements with an href
attribute and a rel
attribute, links must be created for the keywords of the rel
attribute, as defined for those keywords in the link types section.
Similarly, for a
and area
elements with an href
attribute and a rel
attribute, links must be created for the keywords of the rel
attribute as defined for those keywords in the link types section. Unlike link
elements, however, a
and area
elements with an href
attribute that either do not have a rel
attribute, or
whose rel
attribute has no keywords that are defined as
specifying hyperlinks, must also create a hyperlink.
This implied hyperlink has no special meaning (it has no link type)
beyond linking the element’s node document to the resource given by the element’s href
attribute.
A hyperlink can have one or more hyperlink annotations that modify the processing semantics of that hyperlink.
4.8.2. Links created by a
and area
elements
The href
attribute on a
and area
elements must have a value that is a valid URL potentially surrounded by
spaces.
The href
attribute on a
and area
elements is not required; when those elements do not have href
attributes they do not create hyperlinks.
The target
attribute, if present, must be
a valid browsing context name or keyword. It gives the name of the browsing context that will be used. User agents use this name when following hyperlinks.
When an a
or area
element’s activation behavior is
invoked, the user agent may allow the user to indicate a preference regarding whether the
hyperlink is to be used for navigation or whether the resource it
specifies is to be downloaded.
In the absence of a user preference, the default should be navigation if the element has no download
attribute, and should be to download the
specified resource if it does.
Whether determined by the user’s preferences or via the presence or absence of the attribute, if the decision is to use the hyperlink for navigation then the user agent must follow the hyperlink, and if the decision is to use the hyperlink to download a resource, the user agent must download the hyperlink. These terms are defined in subsequent sections below.
The download
attribute, if present,
indicates that the author intends the hyperlink to be used for downloading a resource. The
attribute may have a value; the value, if any, specifies the default file name that the author
recommends for use in labeling the resource in a local file system. There are no restrictions on
allowed values, but authors are cautioned that most file systems have limitations with regard to
what punctuation is supported in file names, and user agents are likely to adjust file names
accordingly.
The rel
attribute on a
and area
elements controls what kinds of links the elements create. The attribute’s value
must be a set of space-separated tokens. The allowed keywords and their meanings are
defined below.
rel
's supported tokens are the keywords defined in HTML link types which are allowed on a
and area
elements, impact the processing model, and are supported by the user agent. The
possible supported tokens are noreferrer
, and noopener
. rel
's supported tokens must only include the tokens from
this list that the user agent implements the processing model for.
Other specifications may add HTML link types as
defined in Other link types. These specifications may require
that their link types be included in rel
's supported
tokens.
The rel
attribute has no default value. If the
attribute is omitted or if none of the values in the attribute are recognized by the user agent,
then the document has no particular relationship with the destination resource other than there
being a hyperlink between the two.
The hreflang
attribute on a
elements that create hyperlinks, if present, gives
the language of the linked resource. It is purely advisory. The value must be a valid BCP 47
language tag. [BCP47] User agents must not consider this attribute
authoritative — upon fetching the resource, user agents must use only language information
associated with the resource to determine its language, not metadata included in the link to the
resource.
The type
attribute, if present, gives the MIME type of the linked resource. It is purely advisory. The value must be a valid mime type. User agents must not consider the type
attribute authoritative — upon fetching the
resource, user agents must not use metadata included in the link to the resource to determine its
type.
4.8.3. API for a
and area
elements
[NoInterfaceObject] interface HTMLHyperlinkElementUtils { stringifier attribute USVString href; readonly attribute USVString origin; attribute USVString protocol; attribute USVString username; attribute USVString password; attribute USVString host; attribute USVString hostname; attribute USVString port; attribute USVString pathname; attribute USVString search; attribute USVString hash; };
- hyperlink .
toString()
- hyperlink .
href
- hyperlink .
-
Returns the hyperlink’s URL.
Can be set, to change the URL.
- hyperlink .
origin
-
Returns the hyperlink’s URL’s origin.
- hyperlink .
protocol
-
Returns the hyperlink’s URL’s scheme.
Can be set, to change the URL’s scheme.
- hyperlink .
username
-
Returns the hyperlink’s URL’s username.
Can be set, to change the URL’s username.
- hyperlink .
password
-
Returns the hyperlink’s URL’s password.
Can be set, to change the URL’s password.
- hyperlink .
host
-
Returns the hyperlink’s URL’s host and port (if different from the default port for the scheme).
Can be set, to change the URL’s host and port.
- hyperlink .
hostname
-
Returns the hyperlink’s URL’s host.
Can be set, to change the URL’s host.
- hyperlink .
port
-
Returns the hyperlink’s URL’s port.
Can be set, to change the URL’s port.
- hyperlink .
pathname
-
Returns the hyperlink’s URL’s path.
Can be set, to change the URL’s path.
- hyperlink .
search
-
Returns the hyperlink’s URL’s query (includes leading "
?
" if non-empty).Can be set, to change the URL’s query (ignores leading "
?
"). - hyperlink .
hash
-
Returns the hyperlink’s URL’s fragment (includes leading "
#
" if non-empty).Can be set, to change the URL’s fragment (ignores leading "
#
").
An element implementing the HTMLHyperlinkElementUtils
mixin has an associated url (null or a URL). It is initially null.
An element implementing the HTMLHyperlinkElementUtils
mixin has an associated set the url algorithm, which sets this
element’s URL to the resulting URL string of parsing this element’s href
content attribute value relative to this element. If parsing was aborted with an error, set this element’s URL to null.
When elements implementing the HTMLHyperlinkElementUtils
mixin are created, and
whenever those elements have their href
content
attribute set, changed, or removed, the user agent must set the url.
This is only observable for blob:
URLs as parsing them involves the StructuredClone abstract algorithm.
An element implementing the HTMLHyperlinkElementUtils
mixin has an associated reinitialise url algorithm, which runs these steps:
- If element’s URL is non-null, its scheme is "
blob
", and its non-relative flag is set, terminate these steps. - Set the url.
To update href
, set the element’s href
content attribute’s value to the element’s URL, serialized.
The href
attribute’s getter must run these
steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url is null and this element has no
href
content attribute, return the empty string. - Otherwise, if url is null, return this element’s
href
content attribute’s value. - Return url, serialized.
The href
attribute’s setter must set this element’s href
content attribute’s value to the given value.
The origin
attribute’s getter must run
these steps:
- Reinitialise url.
- If this element’s URL is null, return the empty string.
- Return the Unicode serialization of this element’s URL’s origin.
It returns the Unicode rather than the ASCII serialization for
compatibility with MessageEvent
.
The protocol
attribute’s getter must
run these steps:
- Reinitialise url.
- If this element’s URL is null, return "
:
". - Return this element’s URL’s scheme, followed by "
:
".
The protocol
attribute’s setter must run these
steps:
- Reinitialise url.
- If this element’s URL is null, terminate these steps.
- Basic URL parse the given value, followed by
:
", with this element’s URL as url and scheme start state as state override. - Update
href
.
The username
attribute’s getter must
run these steps:
- Reinitialise url.
- If this element’s URL is null, return the empty string.
- Return this element’s URL’s username.
The username
attribute’s setter must run these
steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url or url’s host is null, or url’s non-relative flag is set, terminate these steps.
- set the username, given url and the given value.
- Update
href
.
The password
attribute’s getter must
run these steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url or url’s password is null, return the empty string.
- Return url’s password.
The password
attribute’s setter must run these
steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url or url’s host is null, or url’s non-relative flag is set, terminate these steps.
- Set the password, given url and the given value.
- Update
href
.
The host
attribute’s getter must run these
steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url or url’s host is null, return the empty string.
- If url’s port is null, return url’s host, serialized.
- Return url’s host, serialized, followed by "
:
" and url’s port, serialized.
The host
attribute’s setter must run these steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url is null or url’s non-relative flag is set, terminate these steps.
- Basic URL parse the given value, with url as url and host state as state override.
- Update
href
.
The hostname
attribute’s getter must
run these steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url or url’s host is null, return the empty string.
- Return url’s host, serialized.
The hostname
attribute’s setter must run these
steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url is null or url’s non-relative flag is set, terminate these steps.
- Basic URL parse the given value, with url as url and hostname state as state override.
- Update
href
.
The port
attribute’s getter must run these
steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url or url’s port is null, return the empty string.
- Return url’s port, serialized.
The port
attribute’s setter must run these steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url or url’s host is null, url’s non-relative flag is set, or url’s scheme is "
file
", terminate these steps. - Basic URL parse the given value, with url as url and port state as state override.
- Update
href
.
The pathname
attribute’s getter must
run these steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url is null, return the empty string.
- If url’s non-relative flag is set, return the first string in url’s path.
- Return "
/
", followed by the strings in url’s path (including empty strings), separated from each other by "/
".
The pathname
attribute’s setter must run these
steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url is null or url’s non-relative flag is set, terminate these steps.
- Set url’s path to the empty list.
- Basic URL parse the given value, with url as url and path start state as state override.
- Update
href
.
The search
attribute’s getter must run
these steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url is null, or url’s query is either null or the empty string, return the empty string.
- Return "
?
", followed by url’s query.
The search
attribute’s setter must run these
steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url is null, terminate these steps.
- If the given value is the empty string, set url’s query to null.
-
Otherwise, run these substeps:
- Let input be the given value with a single leading "
?
" removed, if any. - Set url’s query to the empty string.
- Basic URL parse input, with url as url and query state as state override, and this element’s node document’s document’s character encoding as encoding override.
- Let input be the given value with a single leading "
- Update
href
.
The hash
attribute’s getter must run these
steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url is null, or url’s fragment is either null or the empty string, return the empty string.
- Return "
#
", followed by url’s fragment.
The hash
attribute’s setter must run these steps:
- Reinitialise url.
- Let url be this element’s URL.
- If url is null or url’s scheme is "
javascript
", terminate these steps. - If the given value is the empty string, set url’s fragment to null.
-
Otherwise, run these substeps:
- Let input be the given value with a single leading "
#
" removed, if any. - Set url’s fragment to the empty string.
- Basic URL parse input, with url as url and fragment state as state override.
- Let input be the given value with a single leading "
- Update
href
.
4.8.4. Following hyperlinks
When a user follows a hyperlink created by an element subject, optionally with a hyperlink suffix, the user agent must run the following steps:
- Let replace be false.
- Let source be the browsing context that contains the
Document
object with which subject in question is associated. -
If the user indicated a specific browsing context when following the hyperlink, or if the user agent is configured to follow hyperlinks by navigating a particular browsing context, then let target be that browsing context. If this is a new top-level browsing context (e.g., when the user followed the hyperlink using "Open in New Tab"), then source must be set as the new browsing context’s one permitted sandboxed navigator.
Otherwise, if subject is an
a
orarea
element that has atarget
attribute, then let target be the browsing context that is chosen by applying the rules for choosing a browsing context given a browsing context name, using the value of thetarget
attribute as the browsing context name. If these rules result in the creation of a new browsing context, set replace to true.Otherwise, if target is an
a
orarea
element with notarget
attribute, but theDocument
contains abase
element with atarget
attribute, then let target be the browsing context that is chosen by applying the rules for choosing a browsing context given a browsing context name, using the value of thetarget
attribute of the first suchbase
element as the browsing context name. If these rules result in the creation of a new browsing context, set replace to true.Otherwise, let target be the browsing context that subject itself is in.
- Parse the URL given by subject’s
href
attribute, relative to subject’s node document. -
If that is successful, let URL be the resulting URL string.
Otherwise, if parsing the URL failed, the user agent may report the error to the user in a user-agent-specific manner, may queue a task to navigate the target browsing context to an error page to report the error, or may ignore the error and do nothing. In any case, the user agent must then abort these steps.
- If there is a hyperlink suffix, append it to URL.
- Queue a task to navigate the target browsing context to URL. If replace is true, the navigation must be performed with replacement enabled. The source browsing context must be source.
The task source for the tasks mentioned above is the DOM manipulation task source.
4.8.5. Downloading resources
In some cases, resources are intended for later use rather than immediate viewing. To indicate
that a resource is intended to be downloaded for use later, rather than immediately used, the download
attribute can be specified on the a
or area
element that creates the hyperlink to that
resource.
The attribute can furthermore be given a value, to specify the file name that user agents are
to use when storing the resource in a file system. This value can be overridden by the Content-Disposition
HTTP header’s filename parameters. [RFC6266]
In cross-origin situations, the download
attribute has to be combined with the Content-Disposition
HTTP header, specifically with the attachment
disposition type, to avoid the user being warned of possibly
nefarious activity. (This is to protect users from being made to download sensitive personal or
confidential information without their full understanding.)
When a user downloads a hyperlink created by an element subject, optionally with a hyperlink suffix, the user agent must run the following steps:
- Parse the URL given by subject’s
href
attribute, relative to subject. - If parsing the URL fails, the user agent may report the error to the user in a user-agent-specific manner, may navigate to an error page to report the error, or may ignore the error and do nothing. In either case, the user agent must abort these steps.
- Otherwise, let URL be the resulting URL string.
- If there is a hyperlink suffix, append it to URL.
- Return to whatever algorithm invoked these steps and continue these steps in parallel.
- Fetch URL and handle the resulting resource as a download.
When a user agent is to handle a resource obtained from a fetch as a download, it should provide the user with a way to save the resource for later use, if a resource is successfully obtained; or otherwise should report any problems downloading the file to the user.
If the user agent needs a file name for a resource being handled as a download, it should select one using the following algorithm.
This algorithm is intended to mitigate security dangers involved in downloading files from untrusted sites, and user agents are strongly urged to follow it.
- Let filename be the void value.
- If the resource has a
Content-Disposition
header, that header specifies theattachment
disposition type, and the header includes file name information, then let filename have the value specified by the header, and jump to the step labeled sanitize below. [RFC6266] - Let interface origin be the origin of the
Document
in which the download or navigate action resulting in the download was initiated, if any. - Let resource origin be the origin of the URL of the
resource being downloaded, unless that URL’s scheme component is
data
, in which case let resource origin be the same as the interface origin, if any. - If there is no interface origin, then let trusted operation be true. Otherwise, let trusted operation be true if resource origin is the same origin as interface origin, and false otherwise.
- If trusted operation is true and the resource has a
Content-Disposition
header and that header includes file name information, then let filename have the value specified by the header, and jump to the step labeled sanitize below. [RFC6266] - If the download was not initiated from a hyperlink created by an
a
orarea
element, or if the element of the hyperlink from which it was initiated did not have adownload
attribute when the download was initiated, or if there was such an attribute but its value when the download was initiated was the empty string, then jump to the step labeled no proposed file name. - Let proposed filename have the value of the
download
attribute of the element of the hyperlink that initiated the download at the time the download was initiated. - If trusted operation is true, let filename have the value of proposed filename, and jump to the step labeled sanitize below.
- If the resource has a
Content-Disposition
header and that header specifies theattachment
disposition type, let filename have the value of proposed filename, and jump to the step labeled sanitize below. [RFC6266] - No proposed file name: If trusted operation is true, or if the user indicated a preference for having the resource in question downloaded, let filename have a value derived from the URL of the resource in a user-agent-defined manner, and jump to the step labeled sanitize below.
-
Act in a user-agent-defined manner to safeguard the user from a potentially hostile cross-origin download. If the download is not to be aborted, then let filename be set to the user’s preferred file name or to a file name selected by the user agent, and jump to the step labeled sanitize below.
If the algorithm reaches this step, then a download was begun from a different origin than the resource being downloaded, and the origin did not mark the file as suitable for downloading, and the download was not initiated by the user. This could be because a
download
attribute was used to trigger the download, or because the resource in question is not of a type that the user agent supports.This could be dangerous, because, for instance, a hostile server could be trying to get a user to unknowingly download private information and then re-upload it to the hostile server, by tricking the user into thinking the data is from the hostile server.
Thus, it is in the user’s interests that the user be somehow notified that the resource in question comes from quite a different source, and to prevent confusion, any suggested file name from the potentially hostile interface origin should be ignored.
- Sanitize: Optionally, allow the user to influence filename. For example, a user agent could prompt the user for a file name, potentially providing the value of filename as determined above as a default value.
-
Adjust filename to be suitable for the local file system.
For example, this could involve removing characters that are not legal in file names, or trimming leading and trailing whitespace.
- If the platform conventions do not in any way use extensions to determine the types of file on the file system, then return filename as the file name and abort these steps.
- Let claimed type be the type given by the resource’s Content-Type metadata, if any is known. Let named type be the type given by filename’s extension, if any is known. For the purposes of this step, a type is a mapping of a MIME type to an extension.
- If named type is consistent with the user’s preferences (e.g., because the value of filename was determined by prompting the user), then return filename as the file name and abort these steps.
- If claimed type and named type are the same type (i.e., the type given by the resource’s Content-Type metadata is consistent with the type given by filename’s extension), then return filename as the file name and abort these steps.
-
If the claimed type is known, then alter filename to add an extension corresponding to claimed type.
Otherwise, if named type is known to be potentially dangerous (e.g., it will be treated by the platform conventions as a native executable, shell script, HTML application, or executable-macro-capable document) then optionally alter filename to add a known-safe extension (e.g., "
.txt
").This last step would make it impossible to download executables, which might not be desirable. As always, implementors are forced to balance security and usability in this matter.
- Return filename as the file name.
For the purposes of this algorithm, a file extension consists of any part of the file name that platform conventions dictate will be used for
identifying the type of the file. For example, many operating systems use the part of the file
name following the last dot (".
") in the file name to determine the type of
the file, and from that the manner in which the file is to be opened or executed.
User agents should ignore any directory or path information provided by the resource itself,
its URL, and any download
attribute, in
deciding where to store the resulting file in the user’s file system.
4.8.6. Link types
The following table summarizes the link types that are defined by this specification. This table is non-normative; the actual definitions for the link types are given in the next few sections.
In this section, the term referenced document refers to the resource identified by the element representing the link, and the term current document refers to the resource within which the element representing the link finds itself.
To determine which link types apply to a link
, a
, or area
element, the element’s rel
attribute must be split on spaces. The resulting tokens are the link types
that apply to that element.
Except where otherwise specified, a keyword must not be specified more than once per rel
attribute.
Link types are always ASCII case-insensitive, and must be compared as such.
Thus, rel="next"
is the same as rel="NEXT"
.
Link type | Effect on... | Brief description | |
---|---|---|---|
link
| a and area
| ||
alternate
| hyperlink | hyperlink | Gives alternate representations of the current document. |
author
| hyperlink | hyperlink | Gives a link to the author of the current document or article. |
bookmark
| not allowed | hyperlink | Gives the permalink for the nearest ancestor section. |
help
| hyperlink | hyperlink | Provides a link to context-sensitive help. |
icon
| External Resource | not allowed | Imports an icon to represent the current document. |
license
| hyperlink | hyperlink | Indicates that the main content of the current document is covered by the copyright license described by the referenced document. |
next
| hyperlink | hyperlink | Indicates that the current document is a part of a series, and that the next document in the series is the referenced document. |
nofollow
| not allowed | Annotation | Indicates that the current document’s original author or publisher does not endorse the referenced document. |
noreferrer
| not allowed | Annotation | Requires that the user agent not send an HTTP Referer (sic) header if the user follows the hyperlink.
|
prev
| hyperlink | hyperlink | Indicates that the current document is a part of a series, and that the previous document in the series is the referenced document. |
search
| hyperlink | hyperlink | Gives a link to a resource that can be used to search through the current document and its related pages. |
stylesheet
| External Resource | not allowed | Imports a stylesheet. |
tag
| not allowed | hyperlink | Gives a tag (identified by the given address) that applies to the current document. |
Some of the types described below list synonyms for these values. These are to be handled as specified by user agents, but must not be used in documents.
4.8.6.1. Link type "alternate
"
The alternate
keyword may be used with link
, a
, and area
elements.
The meaning of this keyword depends on the values of the other attributes.
- If the element is a
link
element and therel
attribute also contains the keywordstylesheet
-
The
alternate
keyword modifies the meaning of thestylesheet
keyword in the way described for that keyword. Thealternate
keyword does not create a link of its own. - If the
alternate
keyword is used with thetype
attribute set to the valueapplication/rss+xml
or the valueapplication/atom+xml
-
The keyword creates a hyperlink referencing a syndication feed (though not necessarily syndicating exactly the same content as the current page).
The first
link
ora
element in the document (in tree order) with thealternate
keyword used with thetype
attribute set to the valueapplication/rss+xml
or the valueapplication/atom+xml
must be treated as the default syndication feed for the purposes of feed autodiscovery.The followinglink
element gives the syndication feed for the current page:<link rel="alternate" type="application/atom+xml" href="data.xml">
The following extract offers various different syndication feeds:
<p>You can access the planets database using Atom feeds:</p> <ul> <li><a href="recently-visited-planets.xml" rel="alternate" type="application/atom+xml">Recently Visited Planets</a></li> <li><a href="known-bad-planets.xml" rel="alternate" type="application/atom+xml">Known Bad Planets</a></li> <li><a href="unexplored-planets.xml" rel="alternate" type="application/atom+xml">Unexplored Planets</a></li> </ul>
- Otherwise
-
The keyword creates a hyperlink referencing an alternate representation of the current document.
The nature of the referenced document is given by the
hreflang
, andtype
attributes.If the
alternate
keyword is used with thehreflang
attribute, and that attribute’s value differs from the root element’s language, it indicates that the referenced document is a translation.If the
alternate
keyword is used with thetype
attribute, it indicates that the referenced document is a reformulation of the current document in the specified format.The
hreflang
andtype
attributes can be combined when specified with thealternate
keyword.For example, the following link is a French translation that uses the PDF format:<link rel=alternate type=application/pdf hreflang=fr href=manual-fr>
This relationship is transitive — that is, if a document links to two other documents with the link type "
alternate
", then, in addition to implying that those documents are alternative representations of the first document, it is also implying that those two documents are alternative representations of each other.
4.8.6.2. Link type "author
"
The author
keyword may be used with link
, a
, and area
elements. This keyword creates a hyperlink.
For a
and area
elements, the author
keyword indicates that the referenced document provides further information about the author of
the nearest article
element ancestor of the element defining the hyperlink, if there
is one, or of the page as a whole, otherwise.
For link
elements, the author
keyword indicates
that the referenced document provides further information about the author for the page as a
whole.
The "referenced document" can be, and often is, a mailto:
URL giving the e-mail address of the author. [RFC6068]
Synonyms: For historical reasons, user agents must also treat link
, a
, and area
elements that have a rev
attribute with the value "made
" as having the author
keyword specified as a link relationship.
4.8.6.3. Link type "bookmark
"
The bookmark
keyword may be used with a
and area
elements. This keyword creates a hyperlink.
The bookmark
keyword gives a permalink for the nearest
ancestor article
element of the linking element in question, or of the section the linking element is most closely associated with, if
there are no ancestor article
elements.
... <body> <h1>Example of permalinks</h1> <div id="a"> <h2>First example</h2> <p><a href="a.html" rel="bookmark">This permalink applies to only the content from the first H2 to the second H2</a>. The DIV isn’t exactly that section, but it roughly corresponds to it.</p> </div> <h2>Second example</h2> <article id="b"> <p><a href="b.html" rel="bookmark">This permalink applies to the outer ARTICLE element</a> (which could be, e.g., a blog post).</p> <article id="c"> <p><a href="c.html" rel="bookmark">This permalink applies to the inner ARTICLE element</a> (which could be, e.g., a blog comment).</p> </article> </article> </body> ...
4.8.6.4. Link type "help
"
The help
keyword may be used with link
, a
, and area
elements. This keyword creates a hyperlink.
For a
and area
elements, the help
keyword indicates that the referenced document provides further help information for the parent of
the element defining the hyperlink, and its children.
<p><label> Topic: <input name=topic> <a href="help/topic.html" rel="help">(Help)</a></label></p>
For link
elements, the help
keyword indicates that
the referenced document provides help for the page as a whole.
For a
and area
elements, on some browsers, the help
keyword causes the link to use a different cursor.
4.8.6.5. Link type "icon
"
The icon
keyword may be used with link
elements.
This keyword creates an external resource link.
The specified resource is an icon representing the page or site, and should be used by the user agent when representing the page in the user interface.
Icons could be auditory icons, visual icons, or other kinds of icons. If
multiple icons are provided, the user agent must select the most appropriate icon according to the type
, media
, and sizes
attributes. If there are multiple equally appropriate icons,
user agents must use the last one declared in tree order at the time that the user
agent collected the list of icons. If the user agent tries to use an icon but that icon is
determined, upon closer examination, to in fact be inappropriate (e.g., because it uses an
unsupported format), then the user agent must try the next-most-appropriate icon as determined by
the attributes.
User agents are not required to update icons when the list of icons changes, but are encouraged to do so.
There is no default type for resources given by the icon
keyword.
However, for the purposes of determining the type of the resource, user agents must expect the resource to be an image.
The sizes
attribute gives the sizes of icons
for visual media. Its value, if present, is merely advisory. User agents may use the value to
decide which icon(s) to use if multiple icons are available.
If specified, the attribute must have a value that is an unordered set of unique
space-separated tokens which are ASCII case-insensitive. Each value must be
either an ASCII case-insensitive match for the string "any
", or a value that consists of two valid non-negative integers that do not have a leading U+0030 DIGIT
ZERO (0) character and that are separated by a single U+0078 LATIN SMALL LETTER X or U+0058 LATIN
CAPITAL LETTER X character.
The keywords represent icon sizes in raw pixels (as opposed to CSS pixels).
An icon that is 50 CSS pixels wide intended for displays with a device pixel density of two device pixels per CSS pixel (2x, 192dpi) would have a width of 100 raw pixels. This feature does not support indicating that a different resource is to be used for small high-resolution icons vs large low-resolution icons (e.g., 50×50 2x vs 100×100 1x).
To parse and process the attribute’s value, the user agent must first split the attribute’s value on spaces, and must then parse each resulting keyword to determine what it represents.
The any
keyword represents that the
resource contains a scalable icon, e.g., as provided by an SVG image.
Other keywords must be further parsed as follows to determine what they represent:
- If the keyword doesn’t contain exactly one U+0078 LATIN SMALL LETTER X or U+0058 LATIN CAPITAL LETTER X character, then this keyword doesn’t represent anything. Abort these steps for that keyword.
- Let width string be the string before the "
x
" or "X
". - Let height string be the string after the "
x
" or "X
". - If either width string or height string start with a U+0030 DIGIT ZERO (0) character or contain any characters other than ASCII digits, then this keyword doesn’t represent anything. Abort these steps for that keyword.
- Apply the rules for parsing non-negative integers to width string to obtain width.
- Apply the rules for parsing non-negative integers to height string to obtain height.
- The keyword represents that the resource contains a bitmap icon with a width of width device pixels and a height of height device pixels.
The keywords specified on the sizes
attribute must not
represent icon sizes that are not actually available in the linked resource.
In the absence of a link
with the icon
keyword, for Document
objects obtained over HTTP or HTTPS, user agents may instead run these
steps in parallel:
- Let request be a new request whose URL is the absolute URL obtained by
resolving the URL "
/favicon.ico
" against the document’s address, client is theDocument
object’sWindow
object’s environment settings object, type is "image
", destination is "subresource
", synchronous flag is set, credentials mode is "include
", and whose use-URL-credentials flag is set. - Let response be the result of fetching request.
- Use response’s unsafe response as an icon as if it had been
declared using the
icon
keyword.
<!DOCTYPE HTML> <html> <head> <title>lsForums — Inbox</title> <link rel=icon href=favicon.png sizes="16x16" type="image/png"> <link rel=icon href=windows.ico sizes="32x32 48x48" type="image/vnd.microsoft.icon"> <link rel=icon href=mac.icns sizes="128x128 512x512 8192x8192 32768x32768"> <link rel=icon href=iphone.png sizes="57x57" type="image/png"> <link rel=icon href=gnome.svg sizes="any" type="image/svg+xml"> <link rel=stylesheet href=lsforums.css> <script src=lsforums.js></script> <meta name=application-name content="lsForums"> </head> <body> ...
For historical reasons, the icon
keyword may be preceded by the
keyword "shortcut
". If the "shortcut
" keyword is
present, the rel
attribute’s entire value must be an ASCII case-insensitive match for the string "shortcut icon
" (with a single U+0020 SPACE character between the tokens and
no other space characters).
4.8.6.6. Link type "license
"
The license
keyword may be used with link
, a
, and area
elements. This keyword creates a hyperlink.
The license
keyword indicates that the referenced document
provides the copyright license terms under which the main content of the current document is
provided.
This specification defines the main content of a document and content that
is not deemed to be part of that main content via the main
element.
The distinction should be made clear to the user.
<!DOCTYPE HTML> <html> <head> <title>Exampl Pictures: Kissat</title> <link rel="stylesheet" href="/style/default"> </head> <body> <h1>Kissat</h1> <nav> <a href="../">Return to photo index</a> </nav> <main> <figure> <img src="/pix/39627052_fd8dcd98b5.jpg"> <figcaption>Kissat</figcaption> </figure> <p>One of them has six toes!</p> <p><small>This photograph is <a rel="license" href="https://www.opensource.org/licenses/mit-license.php">MIT Licensed</a></small></p> </main> <footer> <a href="/">Home</a> | <a href="../">Photo index</a> <p><small>© copyright 2009 Exampl Pictures. All Rights Reserved.</small></p> </footer> </body> </html>
In this case the license
applies to just the photo (the main content of the document), not
the whole document. In particular not the design of the page
itself, which is covered by the copyright given at the bottom of
the document. This should be made clear in the text referencing the licensing
link and could also be made clearer in the styling
(e.g., making the license link prominently positioned near the
photograph, while having the page copyright in small text at
the foot of the page, or adding a border to the main
element.)
Synonyms: For historical reasons, user agents must also treat the keyword
"copyright
" like the license
keyword.
4.8.6.7. Link type "nofollow
"
The nofollow
keyword may be used with a
and area
elements. This keyword does not create a hyperlink, but annotates any other hyperlinks created by the element (the
implied hyperlink, if no other keywords create one).
The nofollow
keyword indicates that the link is not endorsed
by the original author or publisher of the page, or that the link to the referenced document was
included primarily because of a commercial relationship between people affiliated with the two
pages.
4.8.6.8. Link type "noreferrer
"
The noreferrer
keyword may be used with a
and area
elements. This keyword does not create a hyperlink, but annotates any other hyperlinks created by the element (the
implied hyperlink, if no other keywords create one).
It indicates that no referrer information is to be leaked when following the link.
If a user agent follows a link defined by an a
or area
element that
has the noreferrer
keyword, the user agent must set their request’s referrer to "no-referrer
".
This keyword also causes the opener
attribute to remain null if the hyperlink creates a new browsing context.
4.8.6.9. Link type "search
"
The search
keyword may be used with link
, a
, and area
elements. This keyword creates a hyperlink.
The search
keyword indicates that the referenced document
provides an interface specifically for searching the document and its related resources.
OpenSearch description documents can be used with link
elements and
the search
link type to enable user agents to autodiscover search
interfaces. [OPENSEARCH]
4.8.6.10. Link type "stylesheet
"
The stylesheet
keyword may be used with link
elements. This keyword creates an external resource
link that contributes to the styling processing model.
The specified resource is a resource that describes how to present the document. Exactly how the resource is to be processed depends on the actual type of the resource.
If the alternate
keyword is also specified on the link
element, then the link is an alternative stylesheet; in this case,
the title
attribute must be specified on the link
element, with a non-empty value.
The default type for resources given by the stylesheet
keyword is text/css
.
-
When the external resource link is created on a
link
element that is already in aDocument
. -
When the external resource link’s
link
element is inserted into a document. -
When the
href
attribute of thelink
element of an external resource link that is already in aDocument
is changed. -
When the
crossorigin
attribute of thelink
element of an external resource link that is already in aDocument
is set, changed, or removed. -
When the
type
attribute of thelink
element of an external resource link that is already in aDocument
is set or changed to a value that does not or no longer matches the Content-Type metadata of the previous obtained external resource, if any. -
When the
type
attribute of thelink
element of an external resource link that is already in aDocument
but was previously not obtained due to thetype
attribute specifying an unsupported type is set, removed, or changed. -
When the external resource link changes from being an alternative stylesheet to not being one, or vice versa.
Quirk: If the document has been set to quirks mode, has the same origin as the URL of the external resource,
and the Content-Type metadata of the external resource is not a
supported style sheet type, the user agent must instead assume it to be text/css
.
Once a resource has been obtained, if its Content-Type metadata is text/css
, the user
agent must run these steps:
-
Let element be the
link
element that created the external resource link. -
If element has an associated CSS style sheet, remove the CSS style sheet in question.
-
If element no longer creates an external resource link that contributes to the styling processing model, or if, since the resource in question was obtained, it has become appropriate to obtain it again (meaning this algorithm is about to be invoked again for a newly obtained resource), then abort these steps.
-
Create a CSS style sheet with the following properties:
-
text/css
-
The resulting URL string determined during the obtain algorithm.
This is before any redirects get applied.
-
element
-
The
media
attribute of element.This is a reference to the (possibly absent at this time) attribute, rather than a copy of the attribute’s current value. The CSSOM specification defines what happens when the attribute is dynamically set, changed, or removed.
-
The
title
attribute of element.This is similarly a reference to the attribute, rather than a copy of the attribute’s current value.
-
Set if the link is an alternative stylesheet; unset otherwise.
-
Set if the resource is CORS-same-origin; unset otherwise.
-
-
null
-
Left at its default value.
-
Left uninitialized.
The CSS environment encoding is the result of running the following steps: [CSS-SYNTAX-3]
-
If the element has a
charset
attribute, get an encoding from that attribute’s value. If that succeeds, return the resulting encoding and abort these steps. [ENCODING] -
Otherwise, return the document’s character encoding. [DOM]
4.8.6.11. Link type "tag
"
The tag
keyword may be used with a
and area
elements. This keyword creates a hyperlink.
The tag
keyword indicates that the tag that the
referenced document represents applies to the current document.
Since it indicates that the tag applies to the current document, it would be inappropriate to use this keyword in the markup of a tag cloud, which lists the popular tags across a set of pages.
https://en.wikipedia.org/wiki/Gemstone
" to unambiguously categorize it as applying
to the "jewel" kind of gems, and not to, say, the towns in the US, the Ruby package format, or
the Swiss locomotive class:
<!DOCTYPE HTML> <html> <head> <title>My Precious</title> </head> <body> <header><h1>My precious</h1> <p>Summer 2012</p></header> <p>Recently I managed to dispose of a red gem that had been bothering me. I now have a much nicer blue sapphire.</p> <p>The red gem had been found in a bauxite stone while I was digging out the office level, but nobody was willing to haul it away. The same red gem stayed there for literally years.</p> <footer> Tags: <a rel=tag href="https://en.wikipedia.org/wiki/Gemstone">Gemstone</a> </footer> </body> </html>
tag
" link, however, applies
to the whole page (and would do so wherever it was placed, including if it was within the article
elements).
<!DOCTYPE HTML> <html> <head> <title>Gem 4/4</title> </head> <body> <article> <h1>801: Steinbock</h1> <p>The number 801 Gem 4/4 electro-diesel has an ibex and was rebuilt in 2002.</p> </article> <article> <h1>802: Murmeltier</h1> <figure> <img src="https://upload.wikimedia.org/wikipedia/commons/b/b0/Trains_de_la_Bernina_en_hiver_2.jpg" alt="The 802 was red with pantographs and tall vents on the side."> <figcaption>The 802 in the 1980s, above Lago Bianco.</figcaption> </figure> <p>The number 802 Gem 4/4 electro-diesel has a marmot and was rebuilt in 2003.</p> </article> <p class="topic"><a rel=tag href="https://en.wikipedia.org/wiki/Rhaetian_Railway_Gem_4/4">Gem 4/4</a></p> </body> </html>
4.8.6.12. Sequential link types
Some documents form part of a sequence of documents.
A sequence of documents is one where each document can have a previous sibling and a next sibling. A document with no previous sibling is the start of its sequence, a document with no next sibling is the end of its sequence.
A document may be part of multiple sequences.
4.8.6.12.1. Link type "next
"
The next
keyword may be used with link
, a
, and area
elements. This keyword creates a hyperlink.
The next
keyword indicates that the document is part of a
sequence, and that the link is leading to the document that is the next logical document in the
sequence.
4.8.6.12.2. Link type "prev
"
The prev
keyword may be used with link
, a
, and area
elements. This keyword creates a hyperlink.
The prev
keyword indicates that the document is part of a
sequence, and that the link is leading to the document that is the previous logical document in
the sequence.
previous
" like the prev
keyword. 4.8.6.13. Other link types
Extensions to the predefined set of link types may be registered in the microformats wiki existing-rel-values page. [MFREL]
Anyone is free to edit the microformats wiki existing-rel-values page at any time to add a type. Extension types must be specified with the following information:
- Keyword
-
The actual value being defined. The value should not be confusingly similar to any other defined value (e.g., differing only in case).
If the value contains a U+003A COLON character (:), it must also be an absolute URL.
- Effect on...
link
-
One of the following:
- Not allowed
- The keyword must not be specified on
link
elements. - Hyperlink
- The keyword may be specified on a
link
element; it creates a hyperlink. - External Resource
- The keyword may be specified on a
link
element; it creates an external resource link.
- Effect on...
a
andarea
-
One of the following:
- Not allowed
- The keyword must not be specified on
a
andarea
elements. - Hyperlink
- The keyword may be specified on
a
andarea
elements; it creates a hyperlink. - External Resource
- The keyword may be specified on
a
andarea
elements; it creates an external resource link. - Hyperlink Annotation
- The keyword may be specified on
a
andarea
elements; it annotates other hyperlinks created by the element.
- Brief description
- A short non-normative description of what the keyword’s meaning is.
- Specification
- A link to a more detailed description of the keyword’s semantics and requirements. It could be another page on the Wiki, or a link to an external page.
- Synonyms
- A list of other keyword values that have exactly the same processing requirements. Authors should not use the values defined to be synonyms, they are only intended to allow user agents to support legacy content. Anyone may remove synonyms that are not used in practice; only names that need to be processed as synonyms for compatibility with legacy content are to be registered in this way.
- Status
-
One of the following:
- Proposed
- The keyword has not received wide peer review and approval. Someone has proposed it and is, or soon will be, using it.
- Ratified
- The keyword has received wide peer review and approval. It has a specification that unambiguously defines how to handle pages that use the keyword, including when they use it in incorrect ways.
- Discontinued
- The keyword has received wide peer review and it has been found wanting. Existing pages are using this keyword, but new pages should avoid it. The "brief description" and "specification" entries will give details of what authors should use instead, if anything.
If a keyword is found to be redundant with existing values, it should be removed and listed as a synonym for the existing value.
If a keyword is registered in the "proposed" state for a period of a month or more without being used or specified, then it may be removed from the registry.
If a keyword is added with the "proposed" status and found to be redundant with existing values, it should be removed and listed as a synonym for the existing value. If a keyword is added with the "proposed" status and found to be harmful, then it should be changed to "discontinued" status.
Anyone can change the status at any time, but should only do so in accordance with the definitions above.
Conformance checkers may use the information given on the microformats wiki existing-rel-values page to establish if a value is allowed or not: values defined in this specification or marked as "proposed" or "ratified" must be accepted when used on the elements for which they apply as described in the "Effect on..." field, whereas values marked as "discontinued" or values not containing a U+003A COLON character but not listed in either this specification or on the aforementioned page must be reported as invalid. The remaining values must be accepted as valid if they are absolute URLs containing US-ASCII characters only and rejected otherwise. Conformance checkers may cache this information (e.g., for performance reasons or to avoid the use of unreliable network connectivity).
Note: Even URL-valued link types are compared ASCII-case-insensitively. Validators might choose to warn about characters U+0041 (LATIN CAPITAL LETTER A) through U+005A (LATIN CAPITAL LETTER Z) (inclusive) in the pre-case-folded form of link types that contain a colon.
When an author uses a new type not defined by either this specification or the Wiki page, conformance checkers should offer to add the value to the Wiki, with the details described above, with the "proposed" status.
Types defined as extensions in the microformats
wiki existing-rel-values page with the status "proposed" or "ratified" may be used with the rel
attribute on link
, a
, and area
elements in accordance to the "Effect on..." field. [MFREL]
4.9. Tabular data
4.9.1. The table
element
- Categories:
- Flow content.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- In this order: optionally a
caption
element, followed by zero or morecolgroup
elements, followed optionally by athead
element, followed by either zero or moretbody
elements or one or moretr
elements, followed optionally by atfoot
element, optionally intermixed with one or more script-supporting elements. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
border
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLTableElement : HTMLElement { attribute HTMLTableCaptionElement? caption; HTMLTableCaptionElement createCaption(); void deleteCaption(); attribute HTMLTableSectionElement? tHead; HTMLTableSectionElement createTHead(); void deleteTHead(); attribute HTMLTableSectionElement? tFoot; HTMLTableSectionElement createTFoot(); void deleteTFoot(); [SameObject] readonly attribute HTMLCollection tBodies; HTMLTableSectionElement createTBody(); [SameObject] readonly attribute HTMLCollection rows; HTMLTableRowElement insertRow(optional long index = -1); void deleteRow(long index); };
The table
element represents data with more than one dimension, in
the form of a table.
The table
element takes part in the table
model. Tables have rows, columns, and cells given by their descendants. The rows and
columns form a grid; a table’s cells must completely cover that grid without overlap.
Precise rules for determining whether this conformance requirement is met are described in the description of the table model.
Authors are encouraged to provide information describing how to interpret complex tables. Guidance on how to provide such information is given below.
Tables should not be used as layout aids.
Historically, many Web authors have tables in HTML as a way to control their page layout making it difficult to extract tabular data from such documents.
In particular, users of accessibility tools, like screen readers, are likely to find it very difficult to navigate pages with tables used for layout.
If a table is to be used for layout it must be marked with the
attribute role="presentation"
for a
user agent to properly represent the table to an assistive technology and to properly convey the
intent of the author to tools that wish to extract tabular data from
the document.
There are a variety of alternatives to using HTML tables for layout, primarily using CSS positioning and the CSS table model. [CSS-2015]
The border
content attribute may be specified on a table
element to
explicitly indicate that the table
element is not being
used for layout purposes. If specified, the attribute’s value must
either be the empty string or the value "1
".
The attribute is used by certain user agents as an indication that
borders should be drawn around cells of the table.
Tables can be complicated to understand and navigate. To help users with this, user agents should clearly delineate cells in a table from each other, unless the user agent has classified the table as a layout table.
Authors and implementors are encouraged to consider using some of the table design techniques described below to make tables easier to navigate for users.
User agents, especially those that do table analysis on arbitrary content, are encouraged to find heuristics to determine which tables actually contain data and which are merely being used for layout. This specification does not define a precise heuristic, but the following are suggested as possible indicators:
Feature | Indication |
---|---|
The use of the role attribute with the value presentation
| Probably a layout table |
The use of the non-conforming border attribute with the non-conforming value 0
| Probably a layout table |
The use of the non-conforming cellspacing and cellpadding attributes with the value 0
| Probably a layout table |
The use of caption , thead , or th elements
| Probably a non-layout table |
The use of the headers and scope attributes
| Probably a non-layout table |
The use of the non-conforming border attribute with a value other than 0
| Probably a non-layout table |
Explicit visible borders set using CSS | Probably a non-layout table |
The use of the summary attribute
| Not a good indicator (both layout and non-layout tables have historically been given this attribute) |
It is quite possible that the above suggestions are wrong. Implementors are urged to provide feedback elaborating on their experiences with trying to create a layout table detection heuristic.
If a table
element has a (non-conforming) summary
attribute, and the user agent has not classified the
table as a layout table, the user agent may report the contents of that attribute to the user.
- table .
caption
[ = value ] -
Returns the table’s
caption
element.Can be set, to replace the
caption
element. - caption = table .
createCaption
() -
Ensures the table has a
caption
element, and returns it. - table .
deleteCaption
() -
Ensures the table does not have a
caption
element. - table .
tHead
[ = value ] -
Returns the table’s
thead
element.Can be set, to replace the
thead
element. If the new value is not athead
element, throws aHierarchyRequestError
exception. - thead = table .
createTHead
() -
Ensures the table has a
thead
element, and returns it. - table .
deleteTHead
() -
Ensures the table does not have a
thead
element. - table .
tFoot
[ = value ] -
Returns the table’s
tfoot
element.Can be set, to replace the
tfoot
element. If the new value is not atfoot
element, throws aHierarchyRequestError
exception. - tfoot = table .
createTFoot
() -
There is only one known native implementation of
createTFoot
(Firefox/Gecko). Therefore this feature should not be relied upon.Ensures the table has a
tfoot
element, and returns it. - table .
deleteTFoot
() -
Ensures the table does not have a
tfoot
element. - table .
tBodies
-
Returns an
HTMLCollection
of thetbody
elements of the table. - tbody = table .
createTBody
() -
Creates a
tbody
element, inserts it into the table, and returns it. - table .
rows
-
Returns an
HTMLCollection
of thetr
elements of the table. - tr = table .
insertRow
( [ index ] ) -
Creates a
tr
element, along with atbody
if required, inserts them into the table at the position given by the argument, and returns thetr
.The position is relative to the rows in the table. The index -1, which is the default if the argument is omitted, is equivalent to inserting at the end of the table.
If the given position is less than -1 or greater than the number of rows, throws an
IndexSizeError
exception. - table .
deleteRow
(index) -
Removes the
tr
element with the given position in the table.The position is relative to the rows in the table. The index -1 is equivalent to deleting the last row of the table.
If the given position is less than -1 or greater than the index of the last row, or if there are no rows, throws an
IndexSizeError
exception.
The caption
IDL attribute must return, on
getting, the first caption
element child of the table
element, if any,
or null otherwise. On setting, the first caption
element child of the table
element, if any, must be removed, and the new value, if not null, must be
inserted as the first node of the table
element.
The createCaption()
method must return
the first caption
element child of the table
element, if any; otherwise
a new caption
element must be created, inserted as the first node of the table
element, and then returned.
The deleteCaption()
method must remove
the first caption
element child of the table
element, if any.
The tHead
IDL attribute must return, on
getting, the first thead
element child of the table
element, if any, or
null otherwise. On setting, if the new value is null or a thead
element, the first thead
element child of the table
element, if any, must be removed, and
the new value, if not null, must be inserted immediately before the first element in the table
element that is neither a caption
element nor a colgroup
element, if any, or at the end of the table if there are no such elements.
If the new value is neither null nor a thead
element, then a HierarchyRequestError
DOM exception must be thrown instead.
The createTHead()
method must return the
first thead
element child of the table
element, if any; otherwise a new thead
element must be created and inserted immediately before the first element in
the table
element that is neither a caption
element nor a colgroup
element, if any, or at the end of the table if there are no such elements,
and then that new element must be returned.
The deleteTHead()
method must remove the
first thead
element child of the table
element, if any.
The tFoot
IDL attribute must return, on
getting, the first tfoot
element child of the table
element, if any, or
null otherwise. On setting, if the new value is null or a tfoot
element, the first tfoot
element child of the table
element, if any, must be removed, and
the new value, if not null, must be inserted at the end of the table. If the new value is neither
null nor a tfoot
element, then a HierarchyRequestError
DOM exception
must be thrown instead.
The createTFoot()
method must return the
first tfoot
element child of the table
element, if any; otherwise a new tfoot
element must be created and inserted at the end of the table, and then that new
element must be returned.
The deleteTFoot()
method must remove the
first tfoot
element child of the table
element, if any.
The tBodies
attribute must return an HTMLCollection
rooted at the table
node, whose filter matches only tbody
elements that are children of the table
element.
The createTBody()
method must create a
new tbody
element, insert it immediately after the last tbody
element
child in the table
element, if any, or at the end of the table
element
if the table
element has no tbody
element children, and then must return
the new tbody
element.
The rows
attribute must return an HTMLCollection
rooted at the table
node, whose filter matches only tr
elements that are either children of the table
element, or children
of thead
, tbody
, or tfoot
elements that are themselves
children of the table
element. The elements in the collection must be ordered such
that those elements whose parent is a thead
are included first, in tree order,
followed by those elements whose parent is either a table
or tbody
element, again in tree order, followed finally by those elements whose parent is a tfoot
element, still in tree order.
The behavior of the insertRow(index)
method depends on the state of the table. When it is called,
the method must act as required by the first item in the following list of conditions that
describes the state of the table and the index argument:
- If index is less than -1 or greater than the number of elements
in
rows
collection: - The method must throw an
IndexSizeError
exception. - If the
rows
collection has zero elements in it, and thetable
has notbody
elements in it: - The method must create a
tbody
element, then create atr
element, then append thetr
element to thetbody
element, then append thetbody
element to thetable
element, and finally return thetr
element. - If the
rows
collection has zero elements in it: - The method must create a
tr
element, append it to the lasttbody
element in the table, and return thetr
element. - If index is -1 or equal to the number of items in
rows
collection: - The method must create a
tr
element, and append it to the parent of the lasttr
element in therows
collection. Then, the newly createdtr
element must be returned. - Otherwise:
- The method must create a
tr
element, insert it immediately before the indexthtr
element in therows
collection, in the same parent, and finally must return the newly createdtr
element.
When the deleteRow(index)
method is called, the user agent must run the following
steps:
- If index is equal to -1, then index must be
set to the number of items in the
rows
collection, minus one. - Now, if index is less than zero, or greater than or equal to the
number of elements in the
rows
collection, the method must instead throw anIndexSizeError
exception, and these steps must be aborted. - Otherwise, the method must remove the indexth element in the
rows
collection from its parent.
<section> <h1>Today’s Sudoku</h1> <table> <colgroup><col><col><col> <colgroup><col><col><col> <colgroup><col><col><col> <tbody> <tr> <td> 1 <td> <td> 3 <td> 6 <td> <td> 4 <td> 7 <td> <td> 9 <tr> <td> <td> 2 <td> <td> <td> 9 <td> <td> <td> 1 <td> <tr> <td> 7 <td> <td> <td> <td> <td> <td> <td> <td> 6 <tbody> <tr> <td> 2 <td> <td> 4 <td> <td> 3 <td> <td> 9 <td> <td> 8 <tr> <td> <td> <td> <td> <td> <td> <td> <td> <td> <tr> <td> 5 <td> <td> <td> 9 <td> <td> 7 <td> <td> <td> 1 <tbody> <tr> <td> 6 <td> <td> <td> <td> 5 <td> <td> <td> <td> 2 <tr> <td> <td> <td> <td> <td> 7 <td> <td> <td> <td> <tr> <td> 9 <td> <td> <td> 8 <td> <td> 2 <td> <td> <td> 5 </table> </section>
4.9.1.1. Techniques for describing tables
For tables that consist of more than just a grid of cells with headers in the first row and headers in the first column, and for any table in general where the reader might have difficulty understanding the content, authors should include explanatory information introducing the table. This information is useful for all users, but is especially useful for users who cannot see the table, e.g., users of screen readers.
Such explanatory information should introduce the purpose of the table, outline its basic cell structure, highlight any trends or patterns, and generally teach the user how to use the table.
For instance, the following table:
Negative | Characteristic | Positive |
---|---|---|
Sad | Mood | Happy |
Failing | Grade | Passing |
...could benefit from a description explaining the way the table is laid out, something like "Characteristics are given in the second column, with the negative side in the left column and the positive side in the right column".
There are a variety of ways to include this information, such as:
- In prose, surrounding the table
-
<p id="summary">In the following table, characteristics are given in the second column, with the negative side in the left column and the positive side in the right column.</p> <table aria-describedby="summary"> <caption>Characteristics with positive and negative sides</caption> <thead> <tr> <th id="n"> Negative <th> Characteristic <th> Positive <tbody> <tr> <td headers="n r1"> Sad <th id="r1"> Mood <td> Happy <tr> <td headers="n r2"> Failing <th id="r2"> Grade <td> Passing </table>
In the example above the
aria-describedby
attribute is used to explicitly associate the information with the table for assistive technology users. - Next to the table, in the same
figure
-
<figure aria-labelledby="caption"> <p>Characteristics are given in the second column, with the negative side in the left column and the positive side in the right column.</p> <table> <caption id="caption">Characteristics with positive and negative sides</caption> <thead> <tr> <th id="n"> Negative <th> Characteristic <th> Positive <tbody> <tr> <td headers="n r1"> Sad <th id="r1"> Mood <td> Happy <tr> <td headers="n r2"> Failing <th id="r2"> Grade <td> Passing </table> </figure>
The
figure
in this example has been labeled by thetable
caption
usingaria-labelledby
.
Authors may also use other techniques, or combinations of the above techniques, as appropriate.
Regardless of the method used to provide additional descriptive information for a table
, if a table
needs a caption, authors should use a caption
element
as it is the most robust method for providing an accessible caption for a table
.
The best option, of course, rather than writing a description explaining the way the table is laid out, is to adjust the table such that no explanation is needed.
headers
attributes:
<table> <caption>Characteristics with positive and negative sides</caption> <thead> <tr> <th> Characteristic <th> Negative <th> Positive <tbody> <tr> <th> Mood <td> Sad <td> Happy <tr> <th> Grade <td> Failing <td> Passing </table>
4.9.1.2. Techniques for table design
Good table design is key to making tables more readable and usable.
In visual media, providing column and row borders and alternating row backgrounds can be very effective to make complicated tables more readable.
For tables with large volumes of numeric content, using monospaced fonts can help users see patterns, especially in situations where a user agent does not render the borders. (Unfortunately, for historical reasons, not rendering borders on tables is a common default.)
In speech media, table cells can be distinguished by reporting the corresponding headers before reading the cell’s contents, and by allowing users to navigate the table in a grid fashion, rather than serializing the entire contents of the table in source order.
Authors are encouraged to use CSS to achieve these effects.
User agents are encouraged to render tables using these techniques whenever the page does not use CSS and the table is not classified as a layout table.
4.9.2. The caption
element
- Categories:
- None.
- Contexts in which this element can be used:
- As the first element child of a
table
element. - Content model:
- Flow content, but with no descendant
table
elements. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLTableCaptionElement : HTMLElement {};
The caption
element represents the title of the table
that is its parent, if it has a parent and that is a table
element.
The caption
element takes part in the table model.
When a table
element is the only content in a figure
element other
than the figcaption
, the caption
element should be omitted in favor of
the figcaption
.
A caption can introduce context for a table, making it significantly easier to understand.
1 | 2 | 3 | 4 | 5 | 6 | |
---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 |
2 | 3 | 4 | 5 | 6 | 7 | 8 |
3 | 4 | 5 | 6 | 7 | 8 | 9 |
4 | 5 | 6 | 7 | 8 | 9 | 10 |
5 | 6 | 7 | 8 | 9 | 10 | 11 |
6 | 7 | 8 | 9 | 10 | 11 | 12 |
In the abstract, this table is not clear. However, with a caption giving the table’s number (for reference in the main prose) and explaining its use, it makes more sense:
<caption> <p>Table 1. <p>This table shows the total score obtained from rolling two six-sided dice. The first row represents the value of the first die, the first column the value of the second die. The total is given in the cell that corresponds to the values of the two dice. </caption>
This provides the user with more context:
1 | 2 | 3 | 4 | 5 | 6 | |
---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 |
2 | 3 | 4 | 5 | 6 | 7 | 8 |
3 | 4 | 5 | 6 | 7 | 8 | 9 |
4 | 5 | 6 | 7 | 8 | 9 | 10 |
5 | 6 | 7 | 8 | 9 | 10 | 11 |
6 | 7 | 8 | 9 | 10 | 11 | 12 |
4.9.3. The colgroup
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
table
element, after anycaption
elements and before anythead
,tbody
,tfoot
, andtr
elements. - Content model:
- If the
span
attribute is present: Nothing.- If the
span
attribute is absent: Zero or morecol
andtemplate
elements. - If the
- Tag omission in text/html:
- A
colgroup
element’s end tag may be omitted if thecolgroup
element is not immediately followed by a space character or a comment. - Content attributes:
- Global attributes
span
- Number of columns spanned by the element - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLTableColElement : HTMLElement { attribute unsigned long span; };
The colgroup
element represents a group of one or more columns in the table
that is its parent, if it has a
parent and that is a table
element.
If the colgroup
element contains no col
elements, then the element
may have a span
content attribute specified,
whose value must be a valid non-negative integer greater than zero.
The colgroup
element and its span
attribute take part in the table model.
The span
IDL attribute must reflect the content attribute of the same name. The value must be limited to
only non-negative numbers greater than zero.
4.9.4. The col
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
colgroup
element that doesn’t have aspan
attribute. - Content model:
- Nothing.
- Tag omission in text/html:
- No end tag.
- Content attributes:
- Global attributes
span
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
HTMLTableColElement
, same as forcolgroup
elements. This interface defines one member,span
.
If a col
element has a parent and that is a colgroup
element that
itself has a parent that is a table
element, then the col
element represents one or more columns in the column group represented by that colgroup
.
The element may have a span
content attribute
specified, whose value must be a valid non-negative integer greater than zero.
The col
element and its span
attribute take
part in the table model.
The span
IDL attribute must reflect the content attribute of the same name. The value must be limited to only non-negative
numbers greater than zero.
4.9.5. The tbody
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
table
element, after anycaption
,colgroup
, andthead
elements, but only if there are notr
elements that are children of thetable
element. - Content model:
- Zero or more
tr
and script-supporting elements. - Tag omission in text/html:
- A
tbody
element’s start tag may be omitted if the first thing inside thetbody
element is atr
element, and if the element is not immediately preceded by atbody
,thead
, ortfoot
element whose end tag has been omitted. (It can’t be omitted if the element is empty.). Atbody
element’s end tag may be omitted if thetbody
element is immediately followed by atbody
ortfoot
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLTableSectionElement : HTMLElement { [SameObject] readonly attribute HTMLCollection rows; HTMLElement insertRow(optional long index = -1); void deleteRow(long index); };
The
HTMLTableSectionElement
interface is also used forthead
andtfoot
elements.
The tbody
element represents a block of rows that consist of a
body of data for the parent table
element, if the tbody
element has a
parent and it is a table
.
The tbody
element takes part in the table model.
- tbody .
rows
-
Returns an
HTMLCollection
of thetr
elements of the table section. - tr = tbody .
insertRow
( [ index ] ) -
Creates a
tr
element, inserts it into the table section at the position given by the argument, and returns thetr
.The position is relative to the rows in the table section. The index -1, which is the default if the argument is omitted, is equivalent to inserting at the end of the table section.
If the given position is less than -1 or greater than the number of rows, throws an
IndexSizeError
exception. - tbody .
deleteRow
(index) -
Removes the
tr
element with the given position in the table section.The position is relative to the rows in the table section. The index -1 is equivalent to deleting the last row of the table section.
If the given position is less than -1 or greater than the index of the last row, or if there are no rows, throws an
IndexSizeError
exception.
The rows
attribute must return an HTMLCollection
rooted at the element, whose filter matches only tr
elements that are children of the element.
The insertRow(index)
method must, when invoked on an element table section, act as follows:
If index is less than -1 or greater than the number of elements in
the rows
collection, the method must throw an IndexSizeError
exception.
If index is -1 or equal to the number of items in the rows
collection, the method must create a tr
element,
append it to the element table section, and return the newly created tr
element.
Otherwise, the method must create a tr
element, insert it as a child of the table section element, immediately before the indexth tr
element in the rows
collection, and finally
must return the newly created tr
element.
The deleteRow(index)
method
must, when invoked, act as follows:
If index is less than -1 or greater than the number of elements in
the rows
collection, the method must throw an IndexSizeError
exception.
If index is -1, remove the last element in the rows
collection from its parent.
Otherwise, remove the indexth element in the rows
collection from its parent.
4.9.6. The thead
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
table
element, after anycaption
, andcolgroup
elements and before anytbody
,tfoot
, andtr
elements, but only if there are no otherthead
elements that are children of thetable
element. - Content model:
- Zero or more
tr
and script-supporting elements. - Tag omission in text/html:
- A
thead
element’s end tag may be omitted if thethead
element is immediately followed by atbody
ortfoot
element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
HTMLTableSectionElement
, as defined fortbody
elements.
The thead
element represents the block of rows that consist of
the column labels (headers) for the parent table
element, if the thead
element has a parent and it is a table
.
The thead
element takes part in the table model.
thead
element being used. Notice the use of both th
and td
elements in the thead
element: the first row is
the headers, and the second row is an explanation of how to fill in the table.
<table> <caption> School auction sign-up sheet </caption> <thead> <tr> <th><label for=e1>Name</label> <th><label for=e2>Product</label> <th><label for=e3>Picture</label> <th><label for=e4>Price</label> <tr> <td>Your name here <td>What are you selling? <td>Link to a picture <td>Your reserve price <tbody> <tr> <td>Ms Danus <td>Doughnuts <td><img src="https://example.com/mydoughnuts.png" title="Doughnuts from Ms Danus"> <td>$45 <tr> <td><input id=e1 type=text name=who required form=f> <td><input id=e2 type=text name=what required form=f> <td><input id=e3 type=url name=pic form=f> <td><input id=e4 type=number step=0.01 min=0 value=0 required form=f> </table> <form id=f action="/auction.cgi"> <input type=button name=add value="Submit"> </form>
4.9.7. The tfoot
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
table
element, after anycaption
,colgroup
,thead
,tbody
, andtr
elements, but only if there are no othertfoot
elements that are children of thetable
element. - Content model:
- Zero or more
tr
and script-supporting elements. - Tag omission in text/html:
- A
tfoot
element’s end tag may be omitted if thetfoot
element is immediately followed by atbody
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
HTMLTableSectionElement
, as defined fortbody
elements.
The tfoot
element represents the block of rows that consist of
the column summaries (footers) for the parent table
element, if the tfoot
element has a parent and it is a table
.
The tfoot
element takes part in the table model.
4.9.8. The tr
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
thead
element.- As a child of a
tbody
element.- As a child of a
tfoot
element.- As a child of a
table
element, after anycaption
,colgroup
, andthead
elements, but only if there are notbody
elements that are children of thetable
element. - As a child of a
- Content model:
- Zero or more
td
,th
, and script-supporting elements. - Tag omission in text/html:
- A
tr
element’s end tag may be omitted if thetr
element is immediately followed by anothertr
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLTableRowElement : HTMLElement { readonly attribute long rowIndex; readonly attribute long sectionRowIndex; [SameObject] readonly attribute HTMLCollection cells; HTMLElement insertCell(optional long index = -1); void deleteCell(long index); };
The tr
element represents a row of cells in a table.
The tr
element takes part in the table model.
- tr .
rowIndex
-
Returns the position of the row in the table’s
rows
list.Returns -1 if the element isn’t in a table.
- tr .
sectionRowIndex
-
Returns the position of the row in the table section’s
rows
list.Returns -1 if the element isn’t in a table section.
- tr .
cells
-
Returns an
HTMLCollection
of thetd
andth
elements of the row. - cell = tr .
insertCell
( [ index ] ) -
Creates a
td
element, inserts it into the table row at the position given by the argument, and returns thetd
.The position is relative to the cells in the row. The index -1, which is the default if the argument is omitted, is equivalent to inserting at the end of the row.
If the given position is less than -1 or greater than the number of cells, throws an
IndexSizeError
exception. - tr .
deleteCell
(index) -
Removes the
td
orth
element with the given position in the row.The position is relative to the cells in the row. The index -1 is equivalent to deleting the last cell of the row.
If the given position is less than -1 or greater than the index of the last cell, or if there are no cells, throws an
IndexSizeError
exception.
The rowIndex
attribute must, if the element has
a parent table
element, or a parent tbody
, thead
, or tfoot
element and a grandparent table
element, return the index
of the tr
element in that table
element’s rows
collection. If there is no such table
element,
then the attribute must return -1.
The sectionRowIndex
attribute must, if
the element has a parent table
, tbody
, thead
, or tfoot
element, return the index of the tr
element in the parent
element’s rows
collection (for tables, that’s the HTMLTableElement.rows
collection; for table sections, that’s the HTMLTableRowElement.rows
collection). If there is no such
parent element, then the attribute must return -1.
The cells
attribute must return an HTMLCollection
rooted at the tr
element, whose filter matches only td
and th
elements that are children of the tr
element.
The insertCell(index)
method must act as follows:
If index is less than -1 or greater than the number of elements in
the cells
collection, the method must throw an IndexSizeError
exception.
If index is equal to -1 or equal to the number of items in cells
collection, the method must create a td
element,
append it to the tr
element, and return the newly created td
element.
Otherwise, the method must create a td
element, insert it as a child of the tr
element, immediately before the indexth td
or th
element in the cells
collection, and finally
must return the newly created td
element.
The deleteCell(index)
method must act as follows:
If index is less than -1 or greater than the number of elements in
the cells
collection, the method must throw an IndexSizeError
exception.
If index is -1, remove the last element in the cells
collection from its parent.
Otherwise, remove the indexth element in the cells
collection from its parent.
4.9.9. The td
element
- Categories:
- Sectioning root.
- Contexts in which this element can be used:
- As a child of a
tr
element. - Content model:
- Flow content.
- Tag omission in text/html:
- A
td
element’s end tag may be omitted if thetd
element is immediately followed by atd
orth
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
colspan
- Number of columns that the cell is to spanrowspan
- Number of rows that the cell is to spanheaders
- The header cells for this cell - Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLTableDataCellElement : HTMLTableCellElement {};
The td
element represents a data cell in a table.
The td
element and its colspan
, rowspan
, and headers
attributes take part in the table model.
User agents, especially in non-visual environments or where displaying the table as a 2D grid
is impractical, may give the user context for the cell when rendering the contents of a cell; for
instance, giving its position in the table model, or listing the cell’s header cells
(as determined by the algorithm for assigning header cells). When a cell’s header
cells are being listed, user agents may use the value of abbr
attributes on those header cells, if any, instead of the contents of the header cells
themselves.
4.9.10. The th
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
tr
element. - Content model:
- Flow content, but with no
header
,footer
, sectioning content, or heading content descendants - Tag omission in text/html:
- A
th
element’s end tag may be omitted if theth
element is immediately followed by atd
orth
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
colspan
- Number of columns that the cell is to spanrowspan
- Number of rows that the cell is to spanheaders
- The headers for this cellscope
- Specifies which cells the header cell applies toabbr
- Alternative label to use for the header cell when referencing the cell in other contexts - Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLTableHeaderCellElement : HTMLTableCellElement { attribute DOMString scope; attribute DOMString abbr; };
The th
element represents a header cell in a table.
The th
element may have a scope
content attribute specified. The scope
attribute is an enumerated attribute with five states, four of which have explicit keywords:
- The
row
keyword, which maps to the row state - The row state means the header cell applies to some of the subsequent cells in the same row(s).
- The
col
keyword, which maps to the column state - The column state means the header cell applies to some of the subsequent cells in the same column(s).
- The
rowgroup
keyword, which maps to the row group state - The row group state means the header cell applies to all the remaining cells in the
row group. A
th
element’sscope
attribute must not be in the row group state if the element is not anchored in a row group. - The
colgroup
keyword, which maps to the column group state - The colgroup group state means the header cell applies to all the remaining cells in the
column group. A
th
element’sscope
attribute must not be in the column group state if the element is not anchored in a column group. - The auto state
- The auto state makes the header cell apply to a set of cells selected based on context.
The scope
attribute’s missing value default is the auto state.
The th
element may have an abbr
content attribute specified. Its value must be an alternative label for the header cell, to be
used when referencing the cell in other contexts (e.g., when describing the header cells that apply
to a data cell). It is typically an abbreviated form of the full header cell, but can also be an
expansion, or merely a different phrasing.
The th
element and its colspan
, rowspan
, headers
, and scope
attributes take part in the table model.
The scope
IDL attribute must reflect the content attribute of the same name, limited to only known values.
The abbr
IDL attribute must reflect the
content attribute of the same name.
scope
attribute’s rowgroup
value affects which data cells a header cell
applies to.
Here is a markup fragment showing a table:
The tbody
elements in this example identify the range of the row groups.
<table> <caption>Measurement of legs and tails in Cats and English speakers</caption> <thead> <tr> <th> ID <th> Measurement <th> Average <th> Maximum <tbody> <tr> <td> <th scope=rowgroup> Cats <td> <td> <tr> <td> 93 <th scope=row> Legs <td> 3.5 <td> 4 <tr> <td> 10 <th scope=row> Tails <td> 1 <td> 1 </tbody> <tbody> <tr> <td> <th scope=rowgroup> English speakers <td> <td> <tr> <td> 32 <th scope=row> Legs <td> 2.67 <td> 4 <tr> <td> 35 <th scope=row> Tails <td> 0.33 <td> 1 </tbody> </table>
This would result in the following table:
ID | Measurement | Average | Maximum |
---|---|---|---|
Cats | |||
93 | Legs | 3.5 | 4 |
10 | Tails | 1 | 1 |
English speakers | |||
32 | Legs | 2.67 | 4 |
35 | Tails | 0.33 | 1 |
The header cells in row 1 ("ID", "Measurement", "Average" and "Maximum") each apply only to the cells in their column.
The header cells with a scope=rowgroup
("Cats" and 'English speakers') apply to all the cells in their row group other
than the cells (to their left) in column 1:
The header "Cats" (row 2, column 2) applies to the headers "Legs" (row 3, column 2) and "Tails" (row 4, column 2) and to the data cells in rows 2, 3 and 4 of the "Average" and "Maximum" columns.
The header 'English speakers' (row 5, column 2) applies to the headers "Legs" (row 6, column 2) and "Tails" (row 7, column 2) and to the data cells in rows 5, 6 and 7 of the "Average" and "Maximum" columns.
Each of the "Legs" and "Tails" header cells has a scope=row
and therefore apply to the data cells (to the right)
in their row, from the "Average" and "Maximum" columns.
4.9.11. Attributes common to td
and th
elements
The td
and th
elements may have a colspan
content attribute specified, whose value must
be a valid non-negative integer greater than zero.
The td
and th
elements may also have a rowspan
content attribute specified, whose value must
be a valid non-negative integer. For this attribute, the value zero means that the
cell is to span all the remaining rows in the row group.
These attributes give the number of columns and rows respectively that the cell is to span. These attributes must not be used to overlap cells, as described in the description of the table model.
The td
and th
element may have a headers
content attribute specified. The headers
attribute, if specified, must contain a string consisting
of an unordered set of unique space-separated tokens that are case-sensitive, each of which must have the value of an id
of a th
element taking part in the same table as the td
or th
element (as defined by the table model).
A th
element with id
id is
said to be directly targeted by all td
and th
elements in the
same table that have headers
attributes whose values include as one of their tokens
the ID id. A th
element A is said to be targeted by a th
or td
element B if either A is directly targeted by B or if there exists an element C that is itself targeted by the element B and A is directly
targeted by C.
A th
element must not be targeted by itself.
The colspan
, rowspan
, and headers
attributes take part in the table model.
The td
and th
elements implement interfaces that inherit from the HTMLTableCellElement
interface:
interface HTMLTableCellElement : HTMLElement { attribute unsigned long colSpan; attribute unsigned long rowSpan; [PutForwards=value] readonly attribute DOMTokenList headers; readonly attribute long cellIndex; };
- cell .
cellIndex
-
Returns the position of the cell in the row’s
cells
list. This does not necessarily correspond to the x-position of the cell in the table, since earlier cells might cover multiple rows or columns.Returns -1 if the element isn’t in a row.
The colSpan
IDL attribute must reflect the colspan
content attribute. Its
default value is 1.
The rowSpan
IDL attribute must reflect the rowspan
content attribute. Its
default value is 1.
The headers
IDL attribute must reflect the content attribute of the same name.
The cellIndex
IDL attribute must, if the
element has a parent tr
element, return the index of the cell’s element in the parent
element’s cells
collection. If there is no such parent element,
then the attribute must return -1.
4.9.12. Processing model
The various table elements and their content attributes together define the table model.
A table consists of cells aligned on a two-dimensional grid of slots with coordinates (x, y). The grid is finite, and
is either empty or has one or more slots. If the grid has one or more slots, then
the x coordinates are always in the range
0 ≤ x < xwidth,
and the y coordinates are always in the range
0 ≤ y < yheight.
If one or both of xwidth and yheight are zero,
then the table is empty (has no slots). Tables correspond to table
elements.
A cell is a set of slots anchored at a slot
(cellx, celly), and with
a particular width and height such that the cell covers
all the slots with coordinates (x, y) where cellx ≤ x < cellx+width and celly ≤ y < celly+height.
Cells can either be data cells or header cells. Data cells correspond
to td
elements, and header cells correspond to th
elements. Cells of both types
can have zero or more associated header cells.
It is possible, in certain error cases, for two cells to occupy the same slot.
A row is a complete set of slots from x=0 to x=xwidth-1, for a particular value of y. Rows usually
correspond to tr
elements, though a row group can have some implied rows at the end in some cases involving cells spanning multiple rows.
A column is a complete set of slots from y=0 to y=yheight-1, for a particular value of x. Columns can
correspond to col
elements. In the absence of col
elements, columns are
implied.
A row group is a set of rows anchored at a slot (0, groupy) with a particular height such that the row group
covers all the slots with coordinates (x, y) where 0 ≤ x < xwidth and groupy ≤ y < groupy+height. Row groups correspond to tbody
, thead
, and tfoot
elements. Not every row is
necessarily in a row group.
A column group is a set of columns anchored at a slot (groupx, 0) with a particular width such that the column group
covers all the slots with coordinates (x, y) where groupx ≤ x < groupx+width and 0 ≤ y < yheight. Column
groups correspond to colgroup
elements. Not every column is necessarily in a column
group.
Row groups cannot overlap each other. Similarly, column groups cannot overlap each other.
A cell cannot cover slots that are from two or more row groups. It is, however, possible for a cell to be in multiple column groups. All the slots that form part of one cell are part of zero or one row groups and zero or more column groups.
In addition to cells, columns, rows, row groups, and column
groups, tables can have a caption
element
associated with them. This gives the table a heading, or legend.
A table model error is an error with the data represented by table
elements and their descendants. Documents must not have table model errors.
4.9.12.1. Forming a table
User agents must use the following algorithm to determine
- which elements correspond to which slots in a table associated with a
table
element, - the dimensions of the table (xwidth and yheight), and
- if there are any table model errors
.
The algorithm selects the first
caption
encountered and assigns it as thecaption
for the table, and selects the firstthead
and processes it. Until there is athead
,tfoot
,tbody
ortr
element, it processes anycolgroup
elements encountered, and anycol
children, to create column groups. Finally, from the firstthead
,tfoot
,tbody
ortr
element encountered as a child of thetable
it processes those elements, moving the firsttfoot
encountered to the end of the table respectively.-
Let xwidth be zero.
-
Let yheight be zero.
-
Let table footer be null.
-
Let table header be null.
-
Let the table be the table represented by the
table
element. The xwidth and yheight variables give the table’s dimensions. The table is initially empty. -
If the
table
element has no children elements, then return the table (which will be empty), and abort these steps. -
Associate the first
caption
element child of thetable
element with the table. If there are no such children, then it has no associatedcaption
element. -
Let the current element be the first element child of the
table
element.If a step in this algorithm ever requires the current element to be advanced to the next child of the
table
when there is no such next child, then the user agent must jump to the step labeled end, near the end of this algorithm. -
While the current element is not one of the following elements, advance the current element to the next child of the
table
: -
If the current element is a
colgroup
, follow these substeps:-
Column groups: Process the current element according to the appropriate case below:
- If the current element has any
col
element children -
Follow these steps:
-
Let xstart have the value of xwidth.
-
Let the current column be the first
col
element child of thecolgroup
element. -
Columns: If the current column
col
element has aspan
attribute, then parse its value using the rules for parsing non-negative integers.If the result of parsing the value is not an error or zero, then let span be that value.
Otherwise, if the
col
element has nospan
attribute, or if trying to parse the attribute’s value resulted in an error or zero, then let span be 1. -
Increase xwidth by span.
-
Let the last span columns in the table correspond to the current column
col
element. -
If current column is not the last
col
element child of thecolgroup
element, then let the current column be the nextcol
element child of thecolgroup
element, and return to the step labeled columns. -
Let all the last columns in the table from x=xstart to x=xwidth-1 form a new column group, anchored at the slot (xstart, 0), with width xwidth-xstart, corresponding to the
colgroup
element.
-
- If the current element has no
col
element children -
-
If the
colgroup
element has aspan
attribute, then parse its value using the rules for parsing non-negative integers.If the result of parsing the value is not an error or zero, then let span be that value.
Otherwise, if the
colgroup
element has nospan
attribute, or if trying to parse the attribute’s value resulted in an error or zero, then let span be 1. -
Increase xwidth by span.
-
Let the last span columns in the table form a new column group, anchored at the slot (xwidth-span, 0), with width span, corresponding to the
colgroup
element.
-
- If the current element has any
-
While the current element is not one of the following elements, advance the current element to the next child of the
table
: -
If the current element is a
colgroup
element, jump to the step labeled column groups above.
-
-
Let ycurrent be zero.
-
Let the list of downward-growing cells be an empty list.
-
Rows: While the current element is not one of the following elements, advance the current element to the next child of the
table
:Run the algorithm for processing row groups for the first
thead
child of thetable
. -
If the current element is a
tfoot
and the value of table footer is null, then run the following substeps: -
If the current element is a
thead
and the value of table header is null, then run the following substeps: -
If the current element is a
tr
then run the algorithm for processing rows, advance the current element to the next child of thetable
, and return to the step labeled rows. -
Run the algorithm for ending a row group.
-
The current element is either a
thead
,tfoot
, or atbody
.Run the algorithm for processing row groups.
-
Return to the step labeled rows.
-
End: run the algorithm for processing row groups to process table footer.
-
If there exists a row or column in the table containing only slots that do not have a cell anchored to them, then this is a table model error.
-
Return the table.
The algorithm for processing row groups, which is invoked by the set of steps above for processing
thead
,tbody
, andtfoot
elements, is:-
Let ystart have the value of yheight.
-
For each
tr
element that is a child of the element being processed, in tree order, run the algorithm for processing rows. -
If yheight > ystart, then let all the last rows in the table from y=ystart to y=yheight-1 form a new row group, anchored at the slot with coordinate (0, ystart), with height yheight-ystart, corresponding to the element being processed.
-
Run the algorithm for ending a row group.
The algorithm for ending a row group, which is invoked by the set of steps above when starting and ending a block of rows, is:
-
While ycurrent is less than yheight, follow these steps:
-
Increase ycurrent by 1.
-
Empty the list of downward-growing cells.
The algorithm for processing rows, which is invoked by the set of steps above for processing
tr
elements, is:-
If yheight is equal to ycurrent, then increase yheight by
-
(ycurrent is never greater than yheight.)
-
-
Let xcurrent be 0.
-
If the
tr
element being processed has notd
orth
element children, then increase ycurrent by 1, abort this set of steps, and return to the algorithm above. -
Let current cell be the first
td
orth
element child in thetr
element being processed. -
Cells: While xcurrent is less than xwidth and the slot with coordinate (xcurrent, ycurrent) already has a cell assigned to it, increase xcurrent by 1.
-
If xcurrent is equal to xwidth, increase xwidth by 1. (xcurrent is never greater than xwidth.)
-
If the current cell has a
colspan
attribute, then parse that attribute’s value, and let colspan be the result.If parsing that value failed, or returned zero, or if the attribute is absent, then let colspan be 1, instead.
-
If the current cell has a
rowspan
attribute, then parse that attribute’s value, and let rowspan be the result.If parsing that value failed or if the attribute is absent, then let rowspan be 1, instead.
-
If rowspan is zero and the
table
element’s node document is not set to quirks mode, then let cell grows downward be true, and set rowspan to 1. Otherwise, let cell grows downward be false. -
If xwidth < xcurrent+colspan, then let xwidth be xcurrent+colspan.
-
If yheight < ycurrent+rowspan, then let yheight be ycurrent+rowspan.
-
Let the slots with coordinates (x, y) such that xcurrent ≤ x < xcurrent+colspan and ycurrent ≤ y < ycurrent+rowspan be covered by a new cell c, anchored at (xcurrent, ycurrent), which has width colspan and height rowspan, corresponding to the current cell element.
If the current cell element is a
th
element, let this new cell c be a header cell; otherwise, let it be a data cell.To establish which header cells apply to the current cell element, use the algorithm for assigning header cells described in the next section.
If any of the slots involved already had a cell covering them, then this is a table model error. Those slots now have two cells overlapping.
-
If cell grows downward is true, then add the tuple {c, xcurrent, colspan} to the list of downward-growing cells.
-
Increase xcurrent by colspan.
-
If current cell is the last
td
orth
element child in thetr
element being processed, then increase ycurrent by 1, abort this set of steps, and return to the algorithm above. -
Let current cell be the next
td
orth
element child in thetr
element being processed. -
Return to the step labeled cells.
When the algorithms above require the user agent to run the algorithm for growing downward-growing cells, the user agent must, for each {cell, cellx, width} tuple in the list of downward-growing cells, if any, extend the cell cell so that it also covers the slots with coordinates (x, ycurrent), where cellx ≤ x < cellx+width.
4.9.12.2. Forming relationships between data cells and header cells
Each cell can be assigned zero or more header cells. The algorithm for assigning header cells to a cell principal cell is as follows.
-
Let header list be an empty list of cells.
-
Let (principalx, principaly) be the coordinate of the slot to which the principal cell is anchored.
-
- If the principal cell has a
headers
attribute specified -
-
Take the value of the principal cell’s
headers
attribute and split it on spaces, letting id list be the list of tokens obtained. -
For each token in the id list, if the first element in the
Document
with an ID equal to the token is a cell in the same table, and that cell is not the principal cell, then add that cell to header list.
-
- If principal cell does not have a
headers
attribute specified -
-
Let principalwidth be the width of the principal cell.
-
Let principalheight be the height of the principal cell.
-
For each value of y from principaly to principaly+principalheight-1, run the internal algorithm for scanning and assigning header cells, with the principal cell, the header list, the initial coordinate (principalx,y), and the increments Δx=-1 and Δy=0.
-
For each value of x from principalx to principalx+principalwidth-1, run the internal algorithm for scanning and assigning header cells, with the principal cell, the header list, the initial coordinate (x,principaly), and the increments Δx=0 and Δy=-1.
-
If the principal cell is anchored in a row group, then add all header cells that are row group headers and are anchored in the same row group with an x-coordinate less than or equal to principalx+principalwidth-1 and a y-coordinate less than or equal to principaly+principalheight-1 to header list.
-
If the principal cell is anchored in a column group, then add all header cells that are column group headers and are anchored in the same column group with an x-coordinate less than or equal to principalx+principalwidth-1 and a y-coordinate less than or equal to principaly+principalheight-1 to header list.
-
- If the principal cell has a
-
Remove all the empty cells from the header list.
-
Remove any duplicates from the header list.
-
Remove principal cell from the header list if it is there.
-
Assign the headers in the header list to the principal cell.
The internal algorithm for scanning and assigning header cells, given a principal cell, a header list, an initial coordinate (initialx, initialy), and Δx and Δy increments, is as follows:
-
Let x equal initialx.
-
Let y equal initialy.
-
Let opaque headers be an empty list of cells.
-
- If principal cell is a header cell
- Let in header block be true, and let headers from current header block be a list of cells containing just the principal cell.
- Otherwise
- Let in header block be false and let headers from current header block be an empty list of cells.
-
Loop: Increment x by Δx; increment y by Δy.
For each invocation of this algorithm, one of Δx and Δy will be -1, and the other will be 0.
-
If either x or y is less than 0, then abort this internal algorithm.
-
If there is no cell covering slot (x, y), or if there is more than one cell covering slot (x, y), return to the substep labeled loop.
-
Let current cell be the cell covering slot (x, y).
-
- If current cell is a header cell
-
- Set in header block to true.
- Add current cell to headers from current header block.
- Let blocked be false.
-
- If Δx is 0
-
If there are any cells in the opaque headers list anchored with the same x-coordinate as the current cell, and with the same width as current cell, then let blocked be true.
If the current cell is not a column header, then let blocked be true.
- If Δy is 0
-
If there are any cells in the opaque headers list anchored with the same y-coordinate as the current cell, and with the same height as current cell, then let blocked be true.
If the current cell is not a row header, then let blocked be true.
- If blocked is false, then add the current cell to the headers list.
- If current cell is a data cell and in header block is true
- Set in header block to false. Add all the cells in headers from current header block to the opaque headers list, and empty the headers from current header block list.
-
Return to the step labeled loop.
A header cell anchored at the slot with coordinate (x, y) with width width and height height is said to be a column header if any of the following conditions are true:
- The cell’s
scope
attribute is in the column state, or - The cell’s
scope
attribute is in the auto state, and there are no data cells in any of the cells covering slots with y-coordinates y .. y+height-1.
A header cell anchored at the slot with coordinate (x, y) with width width and height height is said to be a row header if any of the following conditions are true:
- The cell’s
scope
attribute is in the row state, or - The cell’s
scope
attribute is in the auto state, the cell is not a column header, and there are no data cells in any of the cells covering slots with x-coordinates x .. x+width-1.
A header cell is said to be a column group header if its
scope
attribute is in the column group state.A header cell is said to be a row group header if its
scope
attribute is in the row group state.A cell is said to be an empty cell if it contains no elements and its text content, if any, consists only of White_Space characters.
-
4.9.13. Examples
This section is non-normative.
The following shows how might one mark up the bottom part of table 45 of the Smithsonian physical tables, Volume 71:
<table> <caption>Specification values: <b>Steel</b>, <b>Castings</b>, Ann. A.S.T.M. A27-16, Class B;* P max. 0.06; S max. 0.05.</caption> <thead> <tr> <th rowspan=2>Grade.</th> <th rowspan=2>Yield Point.</th> <th colspan=2>Ultimate tensile strength</th> <th rowspan=2>Per cent elong. 50.8mm or 2 in.</th> <th rowspan=2>Per cent reduct. area.</th> </tr> <tr> <th>kg/mm<sup>2</sup></th> <th>lb/in<sup>2</sup></th> </tr> </thead> <tbody> <tr> <td>Hard</td> <td>0.45 ultimate</td> <td>56.2</td> <td>80,000</td> <td>15</td> <td>20</td> </tr> <tr> <td>Medium</td> <td>0.45 ultimate</td> <td>49.2</td> <td>70,000</td> <td>18</td> <td>25</td> </tr> <tr> <td>Soft</td> <td>0.45 ultimate</td> <td>42.2</td> <td>60,000</td> <td>22</td> <td>30</td> </tr> </tbody> </table>
This table could look like this:
Grade. | Yield Point. | Ultimate tensile strength | Per cent elong. 50.8 mm or 2 in. | Per cent reduct. area. | |
---|---|---|---|---|---|
kg/mm2 | lb/in2 | ||||
Hard | 0.45 ultimate | 56.2 | 80,000 | 15 | 20 |
Medium | 0.45 ultimate | 49.2 | 70,000 | 18 | 25 |
Soft | 0.45 ultimate | 42.2 | 60,000 | 22 | 30 |
The following shows how one might mark up the gross margin table on page 46 of Apple, Inc’s 10-K filing for fiscal year 2008:
<table> <thead> <tr> <th> <th>2008 <th>2007 <th>2006 <tbody> <tr> <th>Net sales <td>$ 32,479 <td>$ 24,006 <td>$ 19,315 <tr> <th>Cost of sales <td> 21,334 <td> 15,852 <td> 13,717 <tbody> <tr> <th>Gross margin <td>$ 11,145 <td>$ 8,154 <td>$ 5,598 <tfoot> <tr> <th>Gross margin percentage <td>34.3% <td>34.0% <td>29.0% </table>
This table could look like this:
2008 | 2007 | 2006 | |
---|---|---|---|
Net sales | $ 32,479 | $ 24,006 | $ 19,315 |
Cost of sales | 21,334 | 15,852 | 13,717 |
Gross margin | $ 11,145 | $ 8,154 | $ 5,598 |
Gross margin percentage | 34.3% | 34.0% | 29.0% |
The following shows how one might mark up the operating expenses table from lower on the same page of that document:
<table> <colgroup> <col> <colgroup> <col> <col> <col> <thead> <tr> <th> <th>2008 <th>2007 <th>2006 <tbody> <tr> <th scope=rowgroup> Research and development <td> $ 1,109 <td> $ 782 <td> $ 712 <tr> <th scope=row> Percentage of net sales <td> 3.4% <td> 3.3% <td> 3.7% <tbody> <tr> <th scope=rowgroup> Selling, general, and administrative <td> $ 3,761 <td> $ 2,963 <td> $ 2,433 <tr> <th scope=row> Percentage of net sales <td> 11.6% <td> 12.3% <td> 12.6% </table>
This table could look like this:
2008 | 2007 | 2006 | |
---|---|---|---|
Research and development | $ 1,109 | $ 782 | $ 712 |
Percentage of net sales | 3.4% | 3.3% | 3.7% |
Selling, general, and administrative | $ 3,761 | $ 2,963 | $ 2,433 |
Percentage of net sales | 11.6% | 12.3% | 12.6% |
4.10. Forms
4.10.1. Introduction
This section is non-normative.
A form is a component of a Web page that has form controls, such as text fields, buttons, checkboxes, range controls, or color pickers. A user can interact with such a form, providing data that can then be sent to the server for further processing (e.g., returning the results of a search or calculation). No client-side scripting is needed in many cases, though an API is available so that scripts can augment the user experience or use forms for purposes other than submitting data to a server.
Writing a form consists of several steps, which can be performed in any order: writing the user interface, implementing the server-side processing, and configuring the user interface to communicate with the server.
4.10.1.1. Writing a form’s user interface
This section is non-normative.
For the purposes of this brief introduction, we will create a pizza ordering form.
Any form starts with a form
element, inside which are placed the controls. Most
controls are represented by the input
element, which by default provides a one-line
text field. To label a control, the label
element is used; the label text and the
control itself go inside the label
element. Each area within a form is typically represented
using a div
element. Putting this together, here is how one might ask for the customer’s name:
<form> <div><label>Customer name: <input></label></div> </form>
To let the user select the size of the pizza, we can use a set of radio buttons. Radio buttons
also use the input
element, this time with a type
attribute with the value radio
. To make the radio buttons work as a group, they are
given a common name using the name
attribute. To group a batch
of controls together, such as, in this case, the radio buttons, one can use the fieldset
element. The title of such a group of controls is given by the first element
in the fieldset
, which has to be a legend
element.
<form> <div><label>Customer name: <input></label></div> <fieldset> <legend> Pizza Size </legend> <div><label> <input type=radio name=size> Small </label></div> <div><label> <input type=radio name=size> Medium </label></div> <div><label> <input type=radio name=size> Large </label></div> </fieldset> </form>
Changes from the previous step are highlighted.
To pick toppings, we can use checkboxes. These use the input
element with a type
attribute with the value checkbox
:
<form> <div><label>Customer name: <input></label></div> <fieldset> <legend> Pizza Size </legend> <div><label> <input type=radio name=size> Small </label></div> <div><label> <input type=radio name=size> Medium </label></div> <div><label> <input type=radio name=size> Large </label></div> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <div><label> <input type=checkbox> Bacon </label></div> <div><label> <input type=checkbox> Extra Cheese </label></div> <div><label> <input type=checkbox> Onion </label></div> <div><label> <input type=checkbox> Mushroom </label></div> </fieldset> </form>
The pizzeria for which this form is being written is always making mistakes, so it needs a way
to contact the customer. For this purpose, we can use form controls specifically for telephone
numbers (input
elements with their type
attribute set to tel
) and e-mail addresses
(input
elements with their type
attribute set to email
):
<form> <div><label>Customer name: <input></label></div> <div><label>Telephone: <input type=tel></label></div> <div><label>E-mail address: <input type=email></label></div> <fieldset> <legend> Pizza Size </legend> <div><label> <input type=radio name=size> Small </label></div> <div><label> <input type=radio name=size> Medium </label></div> <div><label> <input type=radio name=size> Large </label></div> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <div><label> <input type=checkbox> Bacon </label></div> <div><label> <input type=checkbox> Extra Cheese </label></div> <div><label> <input type=checkbox> Onion </label></div> <div><label> <input type=checkbox> Mushroom </label></div> </fieldset> </form>
We can use an input
element with its type
attribute set to time
to ask for a delivery time. Many
of these form controls have attributes to control exactly what values can be specified; in this
case, three attributes of particular interest are min
, max
, and step
. These set the
minimum time, the maximum time, and the interval between allowed values (in seconds). This
pizzeria only delivers between 11am and 9pm, and doesn’t promise anything better than 15 minute
increments, which we can mark up as follows:
<form> <div><label>Customer name: <input></label></div> <div><label>Telephone: <input type=tel></label></div> <div><label>E-mail address: <input type=email></label></div> <fieldset> <legend> Pizza Size </legend> <div><label> <input type=radio name=size> Small </label></div> <div><label> <input type=radio name=size> Medium </label></div> <div><label> <input type=radio name=size> Large </label></div> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <div><label> <input type=checkbox> Bacon </label></div> <div><label> <input type=checkbox> Extra Cheese </label></div> <div><label> <input type=checkbox> Onion </label></div> <div><label> <input type=checkbox> Mushroom </label></div> </fieldset> <div><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></div> </form>
The textarea
element can be used to provide a free-form text field. In this
instance, we are going to use it to provide a space for the customer to give delivery
instructions:
<form> <div><label>Customer name: <input></label></div> <div><label>Telephone: <input type=tel></label></div> <div><label>E-mail address: <input type=email></label></div> <fieldset> <legend> Pizza Size </legend> <div><label> <input type=radio name=size> Small </label></div> <div><label> <input type=radio name=size> Medium </label></div> <div><label> <input type=radio name=size> Large </label></div> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <div><label> <input type=checkbox> Bacon </label></div> <div><label> <input type=checkbox> Extra Cheese </label></div> <div><label> <input type=checkbox> Onion </label></div> <div><label> <input type=checkbox> Mushroom </label></div> </fieldset> <div><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></div> <div><label>Delivery instructions: <textarea></textarea></label></div> </form>
Finally, to make the form submittable we use the button
element:
<form> <div><label>Customer name: <input></label></div> <div><label>Telephone: <input type=tel></label></div> <div><label>E-mail address: <input type=email></label></div> <fieldset> <legend> Pizza Size </legend> <div><label> <input type=radio name=size> Small </label></div> <div><label> <input type=radio name=size> Medium </label></div> <div><label> <input type=radio name=size> Large </label></div> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <div><label> <input type=checkbox> Bacon </label></div> <div><label> <input type=checkbox> Extra Cheese </label></div> <div><label> <input type=checkbox> Onion </label></div> <div><label> <input type=checkbox> Mushroom </label></div> </fieldset> <div><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></div> <div><label>Delivery instructions: <textarea></textarea></label></div> <div><button>Submit order</button></div> </form>
4.10.1.2. Implementing the server-side processing for a form
This section is non-normative.
The exact details for writing a server-side processor are out of scope for this specification.
For the purposes of this introduction, we will assume that the script at https://pizza.example.com/order.cgi
is configured to accept submissions using the application/x-www-form-urlencoded
format,
expecting the following parameters sent in an HTTP POST body:
-
custname
-
Customer’s name
-
custtel
-
Customer’s telephone number
-
custemail
-
Customer’s e-mail address
-
size
-
The pizza size, either
small
,medium
, orlarge
-
topping
-
A topping, specified once for each selected topping, with the allowed values being
bacon
,cheese
,onion
, andmushroom
-
delivery
-
The requested delivery time
-
comments
-
The delivery instructions
4.10.1.3. Configuring a form to communicate with a server
This section is non-normative.
Form submissions are exposed to servers in a variety of ways, most commonly as HTTP GET or
POST requests. To specify the exact method used, the method
attribute is specified on the form
element. This doesn’t specify how the form data is
encoded, though; to specify that, you use the enctype
attribute. You also have to specify the URL of the service that will handle the
submitted data, using the action
attribute.
For each form control you want submitted, you then have to give a name that will be used to
refer to the data in the submission. We already specified the name for the group of radio buttons;
the same attribute (name
) also specifies the submission name.
Radio buttons can be distinguished from each other in the submission by giving them different
values, using the value
attribute.
Multiple controls can have the same name; for example, here we give all the checkboxes the same
name, and the server distinguishes which checkbox was checked by seeing which values are submitted
with that name — like the radio buttons, they are also given unique values with the value
attribute.
Given the settings in the previous section, this all becomes:
<form method="post" enctype="application/x-www-form-urlencoded" action="https://pizza.example.com/order.cgi"> <p><label>Customer name: <input name="custname"></label></p> <p><label>Telephone: <input type=tel name="custtel"></label></p> <p><label>E-mail address: <input type=email name="custemail"></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size value="small"> Small </label></p> <p><label> <input type=radio name=size value="medium"> Medium </label></p> <p><label> <input type=radio name=size value="large"> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p> <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p> <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p> <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery"></label></p> <p><label>Delivery instructions: <textarea name="comments"></textarea></label></p> <p><button>Submit order</button></p> </form>
There is no particular significance to the way some of the attributes have their values quoted and others don’t. The HTML syntax allows a variety of equally valid ways to specify attributes, as discussed in §8 The HTML syntax.
For example, if the customer entered "Denise Lawrence" as their name, "555-321-8642" as their telephone number, did not specify an e-mail address, asked for a medium-sized pizza, selected the Extra Cheese and Mushroom toppings, entered a delivery time of 7pm, and left the delivery instructions text field blank, the user agent would submit the following to the online Web service:
custname=Denise+Lawrence&custtel=555-321-8642&custemail=&size=medium&topping=cheese&topping=mushroom&delivery=19%3A00&comments=
4.10.1.4. Client-side form validation
This section is non-normative.
Forms can be annotated in such a way that the user agent will check the user’s input before the form is submitted. The server still has to verify the input is valid (since hostile users can easily bypass the form validation), but it allows the user to avoid the wait incurred by having the server be the sole checker of the user’s input.
The simplest annotation is the required
attribute,
which can be specified on input
elements to indicate that the form is not to be
submitted until a value is given. By adding this attribute to the customer name, pizza size, and
delivery time fields, we allow the user agent to notify the user when the user submits the form
without filling in those fields:
<form method="post" enctype="application/x-www-form-urlencoded" action="https://pizza.example.com/order.cgi"> <p><label>Customer name: <input name="custname" required></label></p> <p><label>Telephone: <input type=tel name="custtel"></label></p> <p><label>E-mail address: <input type=email name="custemail"></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size required value="small"> Small </label></p> <p><label> <input type=radio name=size required value="medium"> Medium </label></p> <p><label> <input type=radio name=size required value="large"> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p> <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p> <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p> <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p> <p><label>Delivery instructions: <textarea name="comments"></textarea></label></p> <p><button>Submit order</button></p> </form>
It is also possible to limit the length of the input, using the maxlength
attribute. By adding this to the textarea
element, we can limit users to 1000 characters, preventing them from writing huge essays to the
busy delivery drivers instead of staying focused and to the point:
<form method="post" enctype="application/x-www-form-urlencoded" action="https://pizza.example.com/order.cgi"> <p><label>Customer name: <input name="custname" required></label></p> <p><label>Telephone: <input type=tel name="custtel"></label></p> <p><label>E-mail address: <input type=email name="custemail"></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size required value="small"> Small </label></p> <p><label> <input type=radio name=size required value="medium"> Medium </label></p> <p><label> <input type=radio name=size required value="large"> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p> <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p> <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p> <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p> <p><label>Delivery instructions: <textarea name="comments" maxlength=1000></textarea></label></p> <p><button>Submit order</button></p> </form>
When a form is submitted, invalid
events are
fired at each form control that is invalid, and then at the form
element itself. This
can be useful for displaying a summary of the problems with the form, since typically the browser
itself will only report one problem at a time.
4.10.1.5. Enabling client-side automatic filling of form controls
This section is non-normative.
Some browsers attempt to aid the user by automatically filling form controls rather than having the user reenter their information each time. For example, a field asking for the user’s telephone number can be automatically filled with the user’s phone number.
To help the user agent with this, the autocomplete
attribute can be used to describe the field’s purpose. In the case of this form, we have three
fields that can be usefully annotated in this way: the information about who the pizza is to be
delivered to. Adding this information looks like this:
<form method="post" enctype="application/x-www-form-urlencoded" action="https://pizza.example.com/order.cgi"> <p><label>Customer name: <input name="custname" required autocomplete="shipping name"></label></p> <p><label>Telephone: <input type=tel name="custtel" autocomplete="shipping tel"></label></p> <p><label>E-mail address: <input type=email name="custemail" autocomplete="shipping email"></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size required value="small"> Small </label></p> <p><label> <input type=radio name=size required value="medium"> Medium </label></p> <p><label> <input type=radio name=size required value="large"> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p> <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p> <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p> <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p> <p><label>Delivery instructions: <textarea name="comments" maxlength=1000></textarea></label></p> <p><button>Submit order</button></p> </form>
4.10.1.6. Improving the user experience on mobile devices
This section is non-normative.
Some devices, in particular those with on-screen keyboards and those in locales with languages with many characters (e.g., Japanese), can provide the user with multiple input modalities. For example, when typing in a credit card number the user may wish to only see keys for digits 0-9, while when typing in their name they may wish to see a form field that by default capitalizes each word.
Using the inputmode
attribute we can select appropriate
input modalities:
<form method="post" enctype="application/x-www-form-urlencoded" action="https://pizza.example.com/order.cgi"> <p><label>Customer name: <input name="custname" required autocomplete="shipping name" inputmode="latin-name"></label></p> <p><label>Telephone: <input type=tel name="custtel" autocomplete="shipping tel"></label></p> <p><label>E-mail address: <input type=email name="custemail" autocomplete="shipping email"></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size required value="small"> Small </label></p> <p><label> <input type=radio name=size required value="medium"> Medium </label></p> <p><label> <input type=radio name=size required value="large"> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p> <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p> <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p> <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p> <p><label>Delivery instructions: <textarea name="comments" maxlength=1000 inputmode="latin-prose"></textarea></label></p> <p><button>Submit order</button></p> </form>
4.10.1.7. The difference between the field type, the autofill field name, and the input modality
This section is non-normative.
The type
, autocomplete
, and inputmode
attributes can seem confusingly similar. For instance,
in all three cases, the string "email
" is a valid value. This section
attempts to illustrate the difference between the three attributes and provides advice suggesting
how to use them.
The type
attribute on input
elements decides
what kind of control the user agent will use to expose the field. Choosing between different
values of this attribute is the same choice as choosing whether to use an input
element, a textarea
element, a select
element, a keygen
element, etc.
The autocomplete
attribute, in contrast, describes
what the value that the user will enter actually represents. Choosing between different values of
this attribute is the same choice as choosing what the label for the element will be.
First, consider telephone numbers. If a page is asking for a telephone number from the user,
the right form control to use is <input type=tel>
.
However, which autocomplete
value to use depends on
which phone number the page is asking for, whether they expect a telephone number in the
international format or just the local format, and so forth.
For example, a page that forms part of a checkout process on an e-commerce site for a customer buying a gift to be shipped to a friend might need both the buyer’s telephone number (in case of payment issues) and the friend’s telephone number (in case of delivery issues). If the site expects international phone numbers (with the country code prefix), this could thus look like this:
<p><label>Your phone number: <input type=tel name=custtel autocomplete="billing tel"></label> <p><label>Recipient’s phone number: <input type=tel name=shiptel autocomplete="shipping tel"></label> <p>Please enter complete phone numbers including the country code prefix, as in "+1 555 123 4567".
But if the site only supports British customers and recipients, it might instead look like this
(notice the use of tel-national
rather than tel
):
<p><label>Your phone number: <input type=tel name=custtel autocomplete="billing tel-national"></label> <p><label>Recipient’s phone number: <input type=tel name=shiptel autocomplete="shipping tel-national"></label> <p>Please enter complete UK phone numbers, as in "(01632) 960 123".
Now, consider a person’s preferred languages. The right autocomplete
value is language
. However, there could be a number of
different form controls used for the purpose: a free text field (<input type=text>
), a drop-down list (<select>
), radio buttons (<input
type=radio>
), etc. It only depends on what kind of interface is desired.
The inputmode
decides what kind of input modality (e.g.,
keyboard) to use, when the control is a free-form text field.
Consider names. If a page just wants one name from the user, then the relevant control is <input type=text>
. If the page is asking for the user’s
full name, then the relevant autocomplete
value is name
. But if the user is Japanese, and the page is asking
for the user’s Japanese name and the user’s romanized name, then it would be helpful to the user
if the first field defaulted to a Japanese input modality, while the second defaulted to a Latin
input modality (ideally with automatic capitalization of each word). This is where the inputmode
attribute can help:
<p><label>Japanese name: <input name="j" type="text" autocomplete="section-jp name" inputmode="kana"></label> <label>Romanized name: <input name="e" type="text" autocomplete="section-en name" inputmode="latin-name"></label>
In this example, the "section-*
" keywords in
the autocomplete
attributes' values tell the user agent
that the two fields expect different names. Without them, the user agent could
automatically fill the second field with the value given in the first field when the user gave a
value to the first field.
The "-jp
" and "-en
" parts of the
keywords are opaque to the user agent; the user agent cannot guess, from those, that the two names
are expected to be in Japanese and English respectively.
4.10.1.8. Date, time, and number formats
This section is non-normative.
In this pizza delivery example, the times are specified in the format "HH:MM": two digits for the hour, in 24-hour format, and two digits for the time. (Seconds could also be specified, though they are not necessary in this example.)
In some locales, however, times are often expressed differently when presented to users. For example, in the United States, it is still common to use the 12-hour clock with an am/pm indicator, as in "2pm". In France, it is common to use the 24-hour clock, and separate the hours from the minutes using an "h" character, as in "14h00".
Similar issues exist with dates, with the added complication that even the order of the components is not always consistent — for example, in Cyprus the first of February 2003 would typically be written "1/2/03", while that same date in Japan would typically be written as "2003年02月01日".
The same applies to the way numbers are written in different places. For example, in some locales, such as US English, "1,234" usually means "one thousand two hundred and thirty-four", while "1.234" means "one and two hundred and thirty-four thousandths", or "one point two three four", while in many other locales the meanings are exactly reversed.
The format used "on the wire", i.e., in HTML markup and as the values for form submissions, is intended to be computer-readable and consistent irrespective of the user’s locale, to allow scripts in pages and on servers to process times, dates, and numbers in a consistent manner with minimal work.
In HTML markup and form submission dates and times are always written in a locale-neutral format derived from the ISO-8601 standard. For example, dates are generally in a format such as 2016-06-19.
Likewise, in markup and form submission numbers are always written without grouping separators, and a FULL STOP character "." @@ as a decimal separator.
The time, date, or number may be translated to the user’s preferred presentation (based on expressed preferences or on the locale of the page itself), before being displayed to the user. Similarly, user agents may allow a user to input a time, date, or number using their preferred format, then converts it back to the wire format before putting it in the DOM or submitting it.
This allows scripts in pages and on servers to process times, dates, and numbers in a consistent manner without needing to support dozens of different formats, while still supporting the users' needs.
See also the implementation notes regarding localization of form controls.
4.10.2. Categories
Mostly for historical reasons, elements in this section fall into several overlapping (but subtly different) categories in addition to the usual ones like flow content, phrasing content, and interactive content.
A number of the elements are form-associated elements, which means they can have a form owner.
The form-associated elements fall into several subcategories:
- Listed elements
-
Denotes elements that are listed in the
form.elements
andfieldset.elements
APIs. - Submittable elements
-
Denotes elements that can be used for constructing the form data set when a
form
element is submitted.Some submittable elements can be, depending on their attributes, buttons. The prose below defines when an element is a button. Some buttons are specifically submit buttons.
- Resettable elements
-
Denotes elements that can be affected when a
form
element is reset. - Reassociateable elements
-
Denotes elements that have a
form
content attribute, and a matchingform
IDL attribute, that allow authors to specify an explicit form owner.
Some elements, not all of them form-associated,
are categorized as labelable elements. These are elements that
can be associated with a label
element.
button
input
(if thetype
attribute is not in the state)keygen
meter
output
progress
select
textarea
The following table is non-normative and summarizes the above categories of form elements:
form-associated | listed | submittable | resettable | reassociateable | labelable | |
---|---|---|---|---|---|---|
can have a form owner | listed in the form.elements and fieldset.elements APIs
| can be used for constructing the form data set when a form element is submitted | can be affected when a form element is reset | have a form attribute (allows authors to specify an explicit form owner)
| can be associated with a label element
| |
input
| yes | yes | yes | yes | yes | yes (except "hidden") |
button
| yes | yes | yes | no | yes | yes |
select
| yes | yes | yes | yes | yes | yes |
textarea
| yes | yes | yes | yes | yes | yes |
fieldset
| yes | yes | no | no | yes | no |
output
| yes | yes | no | yes | yes | yes |
object
| yes | yes | yes | no | yes | no |
meter
| no | no | no | no | no | yes |
progress
| no | no | no | no | no | yes |
label
| yes | no | no | no | no | no |
img
| yes | no | no | no | no | no |
4.10.3. The form
element
- Categories:
- Flow content.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content, but with no
form
element descendants. - Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
accept-charset
- Character encodings to use for §4.10.22 Form submissionaction
- URL to use for §4.10.22 Form submissionautocomplete
- Default setting for autofill feature for controls in the formenctype
- Form data set encoding type to use for §4.10.22 Form submissionmethod
- HTTP method to use for §4.10.22 Form submissionname
- Name of form to use in thedocument.forms
APInovalidate
- Bypass form control validation for §4.10.22 Form submissiontarget
- browsing context for §4.10.22 Form submission - Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
[OverrideBuiltins] interface HTMLFormElement : HTMLElement { attribute DOMString acceptCharset; attribute DOMString action; attribute DOMString autocomplete; attribute DOMString enctype; attribute DOMString encoding; attribute DOMString method; attribute DOMString name; attribute boolean noValidate; attribute DOMString target; [SameObject] readonly attribute HTMLFormControlsCollection elements; readonly attribute unsigned long length; getter Element (unsigned long index); getter (RadioNodeList or Element) (DOMString name); void submit(); void reset(); boolean checkValidity(); boolean reportValidity(); };
The form
element represents a collection of form-associated elements, some of which can represent
editable values that can be submitted to a server for processing.
The accept-charset
content attribute gives the
character encodings that are to be used for the submission. If specified, the value must be an ordered set of unique space-separated tokens that are ASCII
case-insensitive, and each token must be an ASCII case-insensitive match for
one of the labels of an ASCII-compatible encoding. [ENCODING]
The name
content attribute represents the form
's name within the forms
collection. The
value must not be the empty string, and the value must be unique amongst the form
elements in the forms
collection that it is in, if any.
The autocomplete
content attribute is an enumerated attribute. The attribute has two states. The on
keyword maps to the on state, and the off
keyword maps to the off state. The attribute may also be omitted. The missing value default is the on state. The off state indicates that by default, form
controls in the form will have their autofill field name set to "off
"; the on state indicates that by default, form controls
in the form will have their autofill field name set to "on
".
The action
, enctype
, method
, enctype
, novalidate
, and target
attributes are attributes for form submission.
- form .
elements
-
Returns an
HTMLFormControlsCollection
of the form controls in the form (excluding image buttons for historical reasons). - form .
length
-
Returns the number of form controls in the form (excluding image buttons for historical reasons).
- form[index]
-
Returns the indexth element in the form (excluding image buttons for historical reasons).
- form[name]
-
Returns the form control (or, if there are several, a
RadioNodeList
of the form controls) in the form with the given ID orname
(excluding image buttons for historical reasons); or, if there are none, returns theimg
element with the given ID.Once an element has been referenced using a particular name, that name will continue being available as a way to reference that element in this method, even if the element’s actual ID or
name
changes, for as long as the element remains in theDocument
.If there are multiple matching items, then a
RadioNodeList
object containing all those elements is returned. - form .
submit()
-
Submits the form.
- form .
reset()
-
Resets the form.
- form .
checkValidity()
-
Returns true if the form’s controls are all valid; otherwise, returns false.
- form .
reportValidity()
-
Returns true if the form’s controls are all valid; otherwise, returns false and informs the user.
The autocomplete
IDL attribute must reflect the content attribute of the same name, limited to only known
values.
The name
IDL attribute must reflect the content attribute of the same name.
The acceptCharset
IDL attribute must reflect the accept-charset
content attribute.
The elements
IDL attribute must return an HTMLFormControlsCollection
rooted at the form
element’s home
subtree’s root element, whose filter matches listed elements whose form owner is the form
element, with the exception of input
elements whose type
attribute is in the image button state, which must, for historical reasons, be
excluded from this particular collection.
The length
IDL attribute must return the number
of nodes represented by the elements
collection.
The supported property indices at any instant are the indices supported by the
object returned by the elements
attribute at that
instant.
When a form
element is indexed for indexed property
retrieval, the user agent must return the value returned by the item
method on the elements
collection, when invoked with the given index as its
argument.
Each form
element has a mapping of names to elements called the past names
map. It is used to persist names of controls even when they change names.
The supported property names consist of the names obtained from the following algorithm, in the order obtained from this algorithm:
- Let sourced names be an initially empty ordered list of tuples consisting of a string, an element, a source, where the source is either id, name, or past, and, if the source is past, an age.
-
For each listed element candidate whose form owner is the
form
element, with the exception of anyinput
elements whosetype
attribute is in the image button state, run these substeps:- If candidate has an
id
attribute, add an entry to sourced names with thatid
attribute’s value as the string, candidate as the element, and id as the source. - If candidate has a
name
attribute, add an entry to sourced names with thatname
attribute’s value as the string, candidate as the element, and name as the source.
- If candidate has an
-
For each
img
element candidate whose form owner is theform
element, run these substeps:- If candidate has an
id
attribute, add an entry to sourced names with thatid
attribute’s value as the string, candidate as the element, and id as the source. - If candidate has a
name
attribute, add an entry to sourced names with thatname
attribute’s value as the string, candidate as the element, and name as the source.
- If candidate has an
-
For each entry past entry in the past names map add an entry to sourced names with the past entry’s name as the string, past entry’s element as the element, past as the source, and the length of time past entry has been in the past names map as the age.
- Sort sourced names by tree order of the element entry of each tuple, sorting entries with the same element by putting entries whose source is id first, then entries whose source is name, and finally entries whose source is past, and sorting entries with the same element and source by their age, oldest first.
- Remove any entries in sourced names that have the empty string as their name.
- Remove any entries in sourced names that have the same name as an earlier entry in the map.
- Return the list of names from sourced names, maintaining their relative order.
The properties exposed in this way must be unenumerable.
When a form
element is indexed for named property
retrieval, the user agent must run the following steps:
- Let candidates be a live
RadioNodeList
object containing all the listed elements whose form owner is theform
element that have either anid
attribute or aname
attribute equal to name, with the exception ofinput
elements whosetype
attribute is in the Image Button state, in tree order. - If candidates is empty, let candidates be a live
RadioNodeList
object containing all theimg
elements that are descendants of theform
element and that have either anid
attribute or aname
attribute equal to name, in tree order. - If candidates is empty, name is the name of one of
the entries in the
form
element’s past names map: return the object associated with name in that map. - If candidates contains more than one node, return candidates and abort these steps.
- Otherwise, candidates contains exactly one node. Add a mapping from name to the node in candidates in the
form
element’s past names map, replacing the previous entry with the same name, if any. - Return the node in candidates.
If an element listed in a form
element’s past names map changes form owner, then its entries must be removed from that map.
The submit()
method, when invoked, must submit the form
element from the form
element itself, with the submitted from submit()
method flag set.
The reset()
method, when invoked, must run the
following steps:
- If the
form
element is marked as locked for reset, then abort these steps. - Mark the
form
element as locked for reset. - Reset the
form
element. - Unmark the
form
element as locked for reset.
If the checkValidity()
method is
invoked, the user agent must statically validate the constraints of the form
element, and return true if the constraint validation return a positive result, and false if it returned a negative result.
If the reportValidity()
method is
invoked, the user agent must interactively validate the constraints of the form
element, and return true if the constraint validation return a positive result, and false if it returned a negative result.
<form action="https://www.google.com/search" method="get"> <label>Google: <input type="search" name="q"></label> <input type="submit" value="Search..."> </form> <form action="https://www.bing.com/search" method="get"> <label>Bing: <input type="search" name="q"></label> <input type="submit" value="Search..."> </form>
4.10.4. The label
element
- Categories:
- Flow content.
- Phrasing content.
- Interactive content.
- Form-associated element.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content, but with no descendant labelable elements unless it is the element’s labeled control, and no descendant
label
elements. - Tag omission in text/html:
- Neither tag is omissable
- Content attributes:
- Global attributes
for
- Associate the label with form control - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLLabelElement : HTMLElement { readonly attribute HTMLFormElement? form; attribute DOMString htmlFor; readonly attribute HTMLElement? control; };
The label
element represents a caption in a user interface. The
caption can be associated with a specific form control, known as the label
element’s labeled control, either using the for
attribute,
or by putting the form control inside the label
element itself.
Except where otherwise specified by the following rules, a label
element has no labeled control.
The for
attribute may be specified to indicate a
form control with which the caption is to be associated. If the attribute is specified, the
attribute’s value must be the ID of a labelable element in the same Document
as the label
element. If the attribute is specified and there is an
element in the Document
whose ID is equal to the
value of the for
attribute, and the first such element is a labelable element, then that element is the label
element’s labeled control.
The following example shows the use of a for
attribute, to associate label
s
which do not contain the element they label.
<form> <table> <caption>Example of using <label
:gt;'sfor
attribute with <label
></caption> <tr> <th><label for="name">Customer name: </label></th> <td><input name="name" id="name"></td> </tr> </table> </form>
Note that the id
attribute is required to associate the for
attribute,
while the name
attribute is required so the value of the input will be submitted as
part of the form.
If the for
attribute is not specified, but the label
element has a labelable element descendant,
then the first such descendant in tree order is the label
element’s labeled control.
The label
element’s activation behavior should match the platform’s label
behavior. Similarly, any additional presentation hints should match the platform’s
label presentation.
label
"Lost" in the following
snippet could trigger the user agent to run synthetic click activation steps on the checkbox, as if the element itself had been triggered by the user, while clicking
the label
"Where?" would queue a task that runs the focusing steps for the element to the text input:
<label><input type="checkbox" name="lost"> Lost</label><br> <label>Where? <input type="text" name="where"></label>
If a label
element has interactive content other than its labeled control, the activation behavior of the label
element for events targeted
at those interactive content descendants and any
descendants of those must be to do nothing.
In the following example, clicking on the link does not toggle the checkbox, even if the platform normally toggles a checkbox when clicking on a label. Instead, clicking the link triggers the normal activation behavior of following the link.
<!-- bad example - link inside label reduces checkbox activation area --> <label><input type=checkbox name=tac>I agree to <a href="tandc.html">the terms and conditions</a></label>
The ability to click or press a label
to trigger an event on a control provides
usability and accessibility benefits by increasing the hit area of a control, making it easier for a user to operate.
These benefits may be lost or reduced, if the label
element contains an element with its own activation
behavior, such as a link:
<!-- bad example - all label text inside the link reduces activation area to checkbox only --> <label><input type=checkbox name=tac><a href="tandc.html">I agree to the terms and conditions</a></label>
The usability and accessibility benefits can be maintained by placing such elements outside the label
element:
<!-- good example - link outside label means checkbox activation area includes the checkbox and all the label text --> <label><input type=checkbox name=tac>I agree to the terms and conditions</label> (read <a href="tandc.html">Terms and Conditions</a>)
<p><label>Full name: <input name=fn> <small>Format: First Last</small></label></p> <p><label>Age: <input name=age type=number min=0></label></p> <p><label>Post code: <input name=pc> <small>Format: AB12 3CD</small></label></p>
- label .
control
-
Returns the form control that is associated with this element.
The htmlFor
IDL attribute must reflect the for
content attribute.
The control
IDL attribute must return the label
element’s labeled control, if any, or null if there isn’t one.
- control .
labels
-
Returns a
NodeList
of all thelabel
elements that the form control is associated with.
Labelable elements have a NodeList
object
associated with them that represents the list of label
elements, in tree
order, whose labeled control is the element in question. The labels
IDL attribute of labelable elements, on getting, must return that NodeList
object.
4.10.5. The input
element
- Categories:
- Flow content.
- Phrasing content.
- If the
type
attribute is not in the Hidden state: interactive content.- If the
type
attribute is not in the Hidden state: listed, labelable, submittable, resettable, and reassociateable form-associated element.- If the
type
attribute is in the Hidden state: listed, submittable, resettable, and reassociateable form-associated element.- If the
type
attribute is not in the Hidden state: Palpable content. - Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag
- Content attributes:
- Global attributes
accept
- Hint for expected file type in file upload controlsalt
- Replacement text for use when images are not availableautocomplete
- Hint for form autofill featureautofocus
- Automatically focus the form control when the page is loadedchecked
- Whether the command or control is checkeddirname
- Name of form field to use for sending the element’s directionality in §4.10.22 Form submissiondisabled
- Whether the form control is disabledform
- Associates the control with aform
elementformaction
- URL to use for §4.10.22 Form submissionformenctype
- Form data set encoding type to use for §4.10.22 Form submissionformmethod
- HTTP method to use for §4.10.22 Form submissionformnovalidate
- Bypass form control validation for §4.10.22 Form submissionformtarget
- browsing context for §4.10.22 Form submissionheight
- Vertical dimensioninputmode
- Hint for selecting an input modalitylist
- List of autocomplete optionsmax
- Maximum valuemaxlength
- Maximum length of valuemin
- Minimum valueminlength
- Minimum length of valuemultiple
- Whether to allow multiple valuesname
- Name of form control to use for §4.10.22 Form submission and in theform.elements
APIpattern
- Pattern to be matched by the form control’s valueplaceholder
- User-visible label to be placed within the form controlreadonly
- Whether to allow the value to be edited by the userrequired
- Whether the control is required for §4.10.22 Form submissionsize
- Size of the controlsrc
- Address of the resourcestep
- Granularity to be matched by the form control’s valuetype
- Type of form controlvalue
- Value of the form controlwidth
- Horizontal dimension- Also, the
title
attribute has special semantics on this element when used in conjunction with thepattern
attribute. - Allowed ARIA role attribute values:
- Depends upon state of the
type
attribute. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLInputElement : HTMLElement { attribute DOMString accept; attribute DOMString alt; attribute DOMString autocomplete; attribute boolean autofocus; attribute boolean defaultChecked; attribute boolean checked; attribute DOMString dirName; attribute boolean disabled; readonly attribute HTMLFormElement? form; readonly attribute FileList? files; attribute DOMString formAction; attribute DOMString formEnctype; attribute DOMString formMethod; attribute boolean formNoValidate; attribute DOMString formTarget; attribute unsigned long height; attribute boolean indeterminate; attribute DOMString inputMode; readonly attribute HTMLElement? list; attribute DOMString max; attribute long maxLength; attribute DOMString min; attribute long minLength; attribute boolean multiple; attribute DOMString name; attribute DOMString pattern; attribute DOMString placeholder; attribute boolean readOnly; attribute boolean required; attribute unsigned long size; attribute DOMString src; attribute DOMString step; attribute DOMString type; attribute DOMString defaultValue; [TreatNullAs=EmptyString] attribute DOMString value; attribute object? valueAsDate; attribute unrestricted double valueAsNumber; attribute unsigned long width; void stepUp(optional long n = 1); void stepDown(optional long n = 1); readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; void select(); attribute unsigned long selectionStart; attribute unsigned long selectionEnd; attribute DOMString selectionDirection; void setRangeText(DOMString replacement); void setRangeText(DOMString replacement, unsigned long start, unsigned long end, optional SelectionMode selectionMode = "preserve"); void setSelectionRange(unsigned long start, unsigned long end, optional DOMString direction); };
The input
element represents a typed data field, usually with a form
control to allow the user to edit the data.
The type
attribute controls the data type of the
element. It is an enumerated attribute. The data type is used to select the control to
use for the input
. Some data types allow either a text field or combo box control to be used,
based on the absence or presence of a list
attribute on the element.
The following table lists the keywords and states for the attribute — the keywords in the
left column map to the state, data type and control(s) in the cells on the same row.
Keyword | State | Data type | Control type |
---|---|---|---|
hidden
| An arbitrary string | n/a | |
text
| Text | Text with no line breaks | A text field or combo box |
search
| Search | Text with no line breaks | Search field or combo box |
tel
| Telephone | Text with no line breaks | A text field or combo box |
url
| URL | An absolute URL | A text field or combo box |
email
| An e-mail address or list of e-mail addresses | A text field or combo box | |
password
| Password | Text with no line breaks (sensitive information) | A text field that obscures data entry |
date
| Date | A date (year, month, day) with no time zone | A date control |
month
| Month | A date consisting of a year and a month with no time zone | A month control |
week
| Week | A date consisting of a week-year number and a week number with no time zone | A week control |
time
| Time | A time (hour, minute, seconds, fractional seconds) with no time zone | A time control |
datetime-local
| Local Date and Time | A local date and time (year, month, day, hour, minute, second, fractional seconds) with no time-zone offset information | A local date and time control |
number
| Number | A numerical value | A text field or combo box or spinner control |
range
| Range | A numerical value, with the extra semantic that the exact value is not important | A slider control or similar |
color
| Color | An sRGB color with 8-bit red, green, and blue components | A color well |
checkbox
| Checkbox | A set of zero or more values from a predefined list | A checkbox |
radio
| Radio Button | An enumerated value | A radio button |
file
| File Upload | Zero or more files each with a MIME type and optionally a file name | A label and a button |
submit
| submit button | An enumerated value, with the extra semantic that it must be the last value selected and initiates form submission | A button |
image
| image button | A coordinate, relative to a particular image’s size, with the extra semantic that it must be the last value selected and initiates form submission | Either a clickable image, or a button |
reset
| reset button | n/a | A button |
button
| Button | n/a | A button |
The missing value default is the Text state.
Which of the accept
, alt
, autocomplete
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, list
, max
, maxlength
, min
, minlength
, multiple
, pattern
, placeholder
, readonly
, required
, size
, src
, step
, and width
content attributes, the checked
, files
, valueAsDate
, valueAsNumber
, and list
IDL attributes, the select()
method, the selectionStart
, selectionEnd
, and selectionDirection
, IDL attributes, the setRangeText()
and setSelectionRange()
methods, the stepUp()
and stepDown()
methods, and the input
and change
events apply to an input
element depends on the state of its type
attribute.
The subsections that define each type also clearly define in normative "bookkeeping" sections
which of these feature apply, and which do not apply, to each type. The behavior of
these features depends on whether they apply or not, as defined in their various sections (q.v.
for Content attributes, for APIs, for events).
The following table is non-normative and summarizes which of those content attributes, IDL attributes, methods, and events apply to each state:
Text, Search | URL, Telephone | Password | Date, Month, Week, Time, Local Date and Time | Number | Range | Color | Checkbox, Radio Button | File Upload | submit button | image button | reset button, Button | |||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Content attributes | ||||||||||||||
accept
| · | · | · | · | · | · | · | · | · | · | Yes | · | · | · |
alt
| · | · | · | · | · | · | · | · | · | · | · | · | Yes | · |
autocomplete
| · | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | · | · | · | · | · |
checked
| · | · | · | · | · | · | · | · | · | Yes | · | · | · | · |
dirname
| · | Yes | · | · | · | · | · | · | · | · | · | · | · | · |
formaction
| · | · | · | · | · | · | · | · | · | · | · | Yes | Yes | · |
formenctype
| · | · | · | · | · | · | · | · | · | · | · | Yes | Yes | · |
formmethod
| · | · | · | · | · | · | · | · | · | · | · | Yes | Yes | · |
formnovalidate
| · | · | · | · | · | · | · | · | · | · | · | Yes | Yes | · |
formtarget
| · | · | · | · | · | · | · | · | · | · | · | Yes | Yes | · |
height
| · | · | · | · | · | · | · | · | · | · | · | · | Yes | · |
inputmode
| · | Yes | · | · | Yes | · | · | · | · | · | · | · | · | · |
list
| · | Yes | Yes | Yes | · | Yes | Yes | Yes | Yes | · | · | · | · | · |
max
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
maxlength
| · | Yes | Yes | Yes | Yes | · | · | · | · | · | · | · | · | · |
min
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
minlength
| · | Yes | Yes | Yes | Yes | · | · | · | · | · | · | · | · | · |
multiple
| · | · | · | Yes | · | · | · | · | · | · | Yes | · | · | · |
pattern
| · | Yes | Yes | Yes | Yes | · | · | · | · | · | · | · | · | · |
placeholder
| · | Yes | Yes | Yes | Yes | · | Yes | · | · | · | · | · | · | · |
readonly
| · | Yes | Yes | Yes | Yes | Yes | Yes | · | · | · | · | · | · | · |
required
| · | Yes | Yes | Yes | Yes | Yes | Yes | · | · | Yes | Yes | · | · | · |
size
| · | Yes | Yes | Yes | Yes | · | · | · | · | · | · | · | · | · |
src
| · | · | · | · | · | · | · | · | · | · | · | · | Yes | · |
step
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
width
| · | · | · | · | · | · | · | · | · | · | · | · | Yes | · |
IDL attributes and methods | ||||||||||||||
checked
| · | · | · | · | · | · | · | · | · | Yes | · | · | · | · |
files
| · | · | · | · | · | · | · | · | · | · | Yes | · | · | · |
value
| default | value | value | value | value | value | value | value | value | default/on | filename | default | default | default |
valueAsDate
| · | · | · | · | · | Yes | · | · | · | · | · | · | · | · |
valueAsNumber
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
list
| · | Yes | Yes | Yes | · | Yes | Yes | Yes | Yes | · | · | · | · | · |
select()
| · | Yes | Yes† | Yes | Yes† | Yes† | Yes† | · | Yes† | · | Yes† | · | · | · |
selectionStart
| · | Yes | Yes | · | Yes | · | · | · | · | · | · | · | · | · |
selectionEnd
| · | Yes | Yes | · | Yes | · | · | · | · | · | · | · | · | · |
selectionDirection
| · | Yes | Yes | · | Yes | · | · | · | · | · | · | · | · | · |
setRangeText()
| · | Yes | Yes | · | Yes | · | · | · | · | · | · | · | · | · |
setSelectionRange()
| · | Yes | Yes | · | Yes | · | · | · | · | · | · | · | · | · |
stepDown()
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
stepUp()
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
Events | ||||||||||||||
input event
| · | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | · | · | · |
change event
| · | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | · | · | · |
† If the control has no text field, the select()
method
results in a no-op, with no "InvalidStateError
" DOMException
.
Some states of the type
attribute define a value sanitization algorithm.
Each input
element has a value, which is
exposed by the value
IDL attribute. Some states define an algorithm to convert a string to a number,
an algorithm to convert a number to a
string, an algorithm to convert a string to a Date
object, and an algorithm to
convert a Date
object to a string, which are used by max
, min
, step
, valueAsDate
, valueAsNumber
, stepDown()
, and stepUp()
.
Each input
element has a boolean dirty value flag. The dirty value flag must be
initially set to false when the element is created, and must be set to true whenever the user
interacts with the control in a way that changes the value.
(It is also set to true when the value is programmatically changed, as described in the definition
of the value
IDL attribute.)
The value
content attribute gives the default value of the input
element. When the value
content attribute is added, set,
or removed, if the control’s dirty value flag is false, the user agent must set the value of the element
to the value of the value
content attribute, if there is
one, or the empty string otherwise, and then run the current value sanitization
algorithm, if one is defined.
Each input
element has a checkedness,
which is exposed by the checked
IDL attribute.
Each input
element has a boolean dirty checkedness flag. When it is true, the
element is said to have a dirty checkedness.
The dirty checkedness flag must be initially
set to false when the element is created, and must be set to true whenever the user interacts with
the control in a way that changes the checkedness.
The checked
content attribute is a boolean attribute that gives the default checkedness of the input
element. When the checked
content attribute is added,
if the control does not have dirty checkedness, the
user agent must set the checkedness of the element to
true; when the checked
content attribute is removed, if
the control does not have dirty checkedness, the user
agent must set the checkedness of the element to
false.
The reset algorithm for input
elements is to set the dirty value flag and dirty checkedness flag back to false, set
the value of the element to the value of the value
content attribute, if there is one, or the empty string
otherwise, set the checkedness of the element to true if
the element has a checked
content attribute and false if
it does not, empty the list of selected
files, and then invoke the value sanitization algorithm, if the type
attribute’s current state defines one.
Each input
element can be mutable. Except where
otherwise specified, an input
element is always mutable. Similarly, except where otherwise specified, the user
agent should not allow the user to modify the element’s value or checkedness.
When an input
element is disabled, it is not mutable.
The readonly
attribute can also in some
cases (e.g., for the Date state, but not the Checkbox state) stop an input
element from
being mutable.
The cloning steps for input
elements
must propagate the value, dirty value flag, checkedness, and dirty checkedness flag from the node being cloned
to the copy.
When an input
element is first created, the element’s rendering and behavior must
be set to the rendering and behavior defined for the type
attribute’s state, and the value sanitization algorithm, if one is defined for the type
attribute’s state, must be invoked.
When an input
element’s type
attribute
changes state, the user agent must run the following steps:
- If the previous state of the element’s
type
attribute put thevalue
IDL attribute in the value mode, and the element’s value is not the empty string, and the new state of the element’stype
attribute puts thevalue
IDL attribute in either the default mode or the default/on mode, then set the element’svalue
content attribute to the element’s value. - Otherwise, if the previous state of the element’s
type
attribute put thevalue
IDL attribute in any mode other than the value mode, and the new state of the element’stype
attribute puts thevalue
IDL attribute in the value mode, then set the value of the element to the value of thevalue
content attribute, if there is one, or the empty string otherwise, and then set the control’s dirty value flag to false. - Otherwise, if the previous state of the element’s
type
attribute put thevalue
IDL attribute in any mode other than the filename mode, and the new state of the element’stype
attribute puts thevalue
IDL attribute in the filename mode, then set the value of the element to the empty string. - Update the element’s rendering and behavior to the new state’s.
- Signal a type change for the element. (The Radio Button state uses this, in particular.)
- Invoke the value sanitization algorithm, if one is defined for the
type
attribute’s new state.
The name
attribute represents the element’s name.
The dirname
attribute controls how the element’s directionality is submitted.
The disabled
attribute is used to make the control non-interactive and to prevent its value from being submitted.
The form
attribute is used to explicitly associate the input
element with its form owner.
The autofocus
attribute controls focus.
The inputmode
attribute controls the user interface’s input modality for the control.
The autocomplete
attribute controls how the user agent provides autofill behavior.
The indeterminate
IDL attribute must
initially be set to false. On getting, it must return the last value it was set to. On setting, it
must be set to the new value. It has no effect except for changing the appearance of checkbox controls.
The accept
, alt
, max
, min
, multiple
, pattern
, placeholder
, required
, size
, src
, and step
IDL attributes must reflect the respective content attributes of the same name.
The dirName
IDL attribute must reflect the dirname
content attribute.
The readOnly
IDL attribute must reflect the readonly
content attribute.
The defaultChecked
IDL attribute must reflect the checked
content attribute.
The defaultValue
IDL attribute must reflect the value
content attribute.
The type
IDL attribute must reflect the respective content attribute of the same name, limited to only known values.
The inputMode
IDL attribute must reflect the inputmode
content attribute, limited to only known values.
The maxLength
IDL attribute must reflect the maxlength
content attribute, limited to only non-negative numbers.
The minLength
IDL attribute must reflect the minlength
content attribute, limited to only non-negative numbers.
The IDL attributes width
and height
must return the rendered
width and height of the image, in CSS pixels, if an image is being rendered, and is
being rendered to a visual medium; or else the intrinsic width and height of the image,
in CSS pixels, if an image is available but not being rendered to a visual medium;
or else 0, if no image is available. When the input
element’s type
attribute is not in the image button state,
then no image is available. [CSS-2015]
On setting, they must act as if they reflected the respective content attributes of the same name.
The willValidate
, validity
, and validationMessage
IDL attributes, and
the checkValidity()
, reportValidity()
, and setCustomValidity()
methods, are part of
the constraint validation API.
The labels
IDL attribute provides a list of the element’s label
s.
The select()
, selectionStart
, selectionEnd
, selectionDirection
, setRangeText()
, and setSelectionRange()
methods and IDL
attributes expose the element’s text selection.
The autofocus
, disabled
, form
, and name
IDL attributes are part of the
element’s forms API.
4.10.5.1. States of the type
attribute
4.10.5.1.1. Hidden state (type=hidden
)
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
The input
element represents a value that is not intended to be
examined or manipulated by the user.
Constraint validation: If an input
element’s type
attribute is in the state, it is barred from constraint
validation.
If the name
attribute is present and has a value that is a case-sensitive match for the string "_charset_
", then the element’s value
attribute must be omitted.
The value
IDL attribute applies to this element and is
in mode default.
The following content attributes must not be specified and do not
apply to the element: accept
, alt
, autocomplete
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, list
, max
, maxlength
, min
, minlength
, multiple
, pattern
, placeholder
, readonly
, required
, size
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the
element: checked
, files
, list
, selectionStart
, selectionEnd
, selectionDirection
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, setRangeText()
, setSelectionRange()
, stepDown()
, and stepUp()
methods.
The input
and change
events do not apply.
4.10.5.1.2. Text (type=text
) state and Search state (type=search
)
- Allowed ARIA role attribute values:
textbox
(default - do not set) orcombobox
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
When an input
element’s type
attribute is in
the Text state or the Search state, the rules in this section apply.
The input
element represents a one line plain text edit control for
the element’s value.
The difference between the Text state and the Search state is primarily stylistic: on platforms where search fields are distinguished from regular text fields, the Search state might result in an appearance consistent with the platform’s search fields rather than appearing like a regular text field.
If the element is mutable, its value should be editable by the user. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the element’s value.
If the element is mutable, the user agent should allow the user to change the writing direction of the element, setting it either to a left-to-right writing direction or a right-to-left writing direction. If the user does so, the user agent must then run the following steps:
- Set the element’s
dir
attribute to "ltr" if the user selected a left-to-right writing direction, and "rtl
" if the user selected a right-to-left writing direction. - Queue a task to fire a simple event that bubbles named
input
at theinput
element.
The value
attribute, if specified, must have a value that
contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.
The value sanitization algorithm is as follows: Strip line breaks from the value.
The following common input
element content
attributes, IDL attributes, and methods apply to the element: autocomplete
, dirname
, inputmode
, list
, maxlength
, minlength
, pattern
, placeholder
, readonly
, required
, and size
content attributes; list
, selectionStart
, selectionEnd
, selectionDirection
, and value
IDL attributes; select()
, setRangeText()
, and setSelectionRange()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element: accept
, alt
, checked
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, max
, min
, multiple
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the
element: checked
, files
, valueAsDate
, and valueAsNumber
IDL attributes; stepDown()
and stepUp()
methods.
4.10.5.1.3. Telephone state (type=tel
)
- Allowed ARIA role attribute values:
textbox
(default - do not set) orcombobox
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
The input
element represents a control for editing a telephone number
given in the element’s value.
If the element is mutable, its value should be editable by the user. User agents may change the spacing and, with care, the punctuation of values that the user enters. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the element’s value.
The value
attribute, if specified, must have a value that
contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.
The value sanitization algorithm is as follows: Strip line breaks from the value.
Unlike the URL and E-mail types, the Telephone type does not enforce a particular syntax. This is
intentional; in practice, telephone number fields tend to be free-form fields, because there are a
wide variety of valid phone numbers. Systems that need to enforce a particular format are
encouraged to use the pattern
attribute or the setCustomValidity()
method to hook into the client-side
validation mechanism.
The following common input
element content
attributes, IDL attributes, and methods apply to the element: autocomplete
, list
, maxlength
, minlength
, pattern
, placeholder
, readonly
, required
, and size
content attributes; list
, selectionStart
, selectionEnd
, selectionDirection
, and value
IDL attributes; select()
, setRangeText()
, and setSelectionRange()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, max
, min
, multiple
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the
element: checked
, files
, valueAsDate
, and valueAsNumber
IDL attributes; stepDown()
and stepUp()
methods.
4.10.5.1.4. URL state (type=url
)
- Allowed ARIA role attribute values:
textbox
(default - do not set) orcombobox
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
The input
element represents a control for editing a single absolute URL given in the element’s value.
If the element is mutable, the user agent should allow the user to change the URL represented by its value. User agents may allow the user to set the value to a string that is not a valid absolute URL, but may also or instead automatically escape characters entered by the user so that the value is always a valid absolute URL (even if that isn’t the actual value seen and edited by the user in the interface). User agents should allow the user to set the value to the empty string. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value.
The value
attribute, if specified and not empty, must
have a value that is a valid URL potentially surrounded by spaces that is also an absolute URL.
The value sanitization algorithm is as follows: Strip line breaks from the value, then strip leading and trailing whitespace from the value.
Constraint validation: While the value of the element is neither the empty string nor a valid absolute URL, the element is suffering from a type mismatch.
The following common input
element content
attributes, IDL attributes, and methods apply to the element: autocomplete
, list
, maxlength
, minlength
, pattern
, placeholder
, readonly
, required
, and size
content attributes; list
, selectionStart
, selectionEnd
, selectionDirection
, and value
IDL attributes; select()
, setRangeText()
, and setSelectionRange()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, max
, min
, multiple
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the
element: checked
, files
, valueAsDate
, and valueAsNumber
IDL attributes; stepDown()
and stepUp()
methods.
<input type="url" name="location" list="urls"> <datalist id="urls"> <option label="MIME: Format of Internet Message Bodies" value="https://tools.ietf.org/html/rfc2045"> <option label="HTML 4.01 Specification" value="https://www.w3.org/TR/html4/"> <option label="Form Controls" value="https://www.w3.org/TR/xforms/slice8.html#ui-commonelems-hint"> <option label="Scalable Vector Graphics (SVG) 1.1 Specification" value="https://www.w3.org/TR/SVG/"> <option label="Feature Sets - SVG 1.1 - 20030114" value="https://www.w3.org/TR/SVG/feature.html"> <option label="The Single UNIX Specification, Version 3" value="https://www.unix-systems.org/version3/"> </datalist>
...and the user had typed "www.w3", and the user agent had also found that the user
had visited https://www.w3.org/Consortium/#membership
and https://www.w3.org/TR/XForms/
in the recent past, then the rendering might look
like this:
The first four URLs in this sample consist of the four URLs in the author-specified list that match the text the user has entered, sorted in some user agent-defined manner (maybe by how frequently the user refers to those URLs). Note how the user agent is using the knowledge that the values are URLs to allow the user to omit the scheme part and perform intelligent matching on the domain name.
The last two URLs (and probably many more, given the scrollbar’s indications of more values being available) are the matches from the user agent’s session history data. This data is not made available to the page DOM. In this particular case, the user agent has no titles to provide for those values.
4.10.5.1.5. E-mail state (type=email
)
- Allowed ARIA role attribute values:
textbox
(default - do not set) orcombobox
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
How the E-mail state operates depends on whether the multiple
attribute is specified or not.
- When the
multiple
attribute is not specified on the element -
The
input
element represents a control for editing an e-mail address given in the element’s value.If the element is mutable, the user agent should allow the user to change the e-mail address represented by its value. User agents may allow the user to set the value to a string that is not a valid e-mail address. The user agent should act in a manner consistent with expecting the user to provide a single e-mail address. User agents should allow the user to set the value to the empty string. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value. User agents may transform the value for display and editing; in particular, user agents should convert punycode in the domain labels of the value to IDN in the display and vice versa.
Constraint validation: While the user interface is representing input that the user agent cannot convert to punycode, the control is suffering from bad input.
The
value
attribute, if specified and not empty, must have a value that is a single valid e-mail address.The value sanitization algorithm is as follows: Strip line breaks from the value, then strip leading and trailing whitespace from the value.
Constraint validation: While the value of the element is neither the empty string nor a single valid e-mail address, the element is suffering from a type mismatch.
- When the
multiple
attribute is specified on the element -
The
input
element represents a control for adding, removing, and editing the e-mail addresses given in the element’s values.If the element is mutable, the user agent should allow the user to add, remove, and edit the e-mail addresses represented by its values. User agents may allow the user to set any individual value in the list of values to a string that is not a valid e-mail address, but must not allow users to set any individual value to a string containing U+002C COMMA (,), U+000A LINE FEED (LF), or U+000D CARRIAGE RETURN (CR) characters. User agents should allow the user to remove all the addresses in the element’s values. User agents may transform the values for display and editing; in particular, user agents should convert punycode in the domain labels of the value to IDN in the display and vice versa.
Constraint validation: While the user interface describes a situation where an individual value contains a U+002C COMMA (,) or is representing input that the user agent cannot convert to punycode, the control is suffering from bad input.
Whenever the user changes the element’s values, the user agent must run the following steps:
- Let latest values be a copy of the element’s values.
- Strip leading and trailing whitespace from each value in latest values.
- Let the element’s value be the result of concatenating all the values in latest values, separating each value from the next by a single U+002C COMMA character (,), maintaining the list’s order.
The
value
attribute, if specified, must have a value that is a valid e-mail address list.The value sanitization algorithm is as follows:
- Split on commas the element’s value, strip leading and trailing whitespace from each resulting token, if any, and let the element’s values be the (possibly empty) resulting list of (possibly empty) tokens, maintaining the original order.
- Let the element’s value be the result of concatenating the element’s values, separating each value from the next by a single U+002C COMMA character (,), maintaining the list’s order.
Constraint validation: While the value of the element is not a valid e-mail address list, the element is suffering from a type mismatch.
When the multiple
attribute is set or removed, the
user agent must run the value sanitization algorithm.
A valid e-mail address is a string that matches the email
production of the following ABNF, the character set for which is Unicode. This ABNF implements the
extensions described in RFC 1123. [ABNF] [RFC5322] [RFC1034] [RFC1123]
email = 1*( atext / "." ) "@" label *( "." label ) label = let-dig [ [ ldh-str ] let-dig ] ; limited to a length of 63 characters by RFC 1034 section 3.5 atext = < as defined in RFC 5322 section 3.2.3 > let-dig = < as defined in RFC 1034 section 3.5 > ldh-str = < as defined in RFC 1034 section 3.5 >
This requirement is a willful violation of RFC 5322, which defines a syntax for e-mail addresses that is simultaneously too strict (before the "@" character), too vague (after the "@" character), and too lax (allowing comments, whitespace characters, and quoted strings in manners unfamiliar to most users) to be of practical use here.
The following JavaScript- and Perl-compatible regular expression is an implementation of the above definition.
/^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/
A valid e-mail address list is a set of comma-separated tokens, where each token is itself a valid e-mail address. To obtain the list of tokens from a valid e-mail address list, an implementation must split the string on commas.
The following common input
element content
attributes, IDL attributes, and methods apply to the element: autocomplete
, list
, maxlength
, minlength
, multiple
, pattern
, placeholder
, readonly
, required
, and size
content attributes; list
and value
IDL attributes; select()
method.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, max
, min
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the
element: checked
, files
, selectionStart
, selectionEnd
, selectionDirection
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, setRangeText()
, setSelectionRange()
, stepDown()
and stepUp()
methods.
4.10.5.1.6. Password state (type=password
)
- Allowed ARIA role attribute values:
textbox
(default - do not set).- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
The input
element represents a one line plain text edit control for
the element’s value. The user agent should obscure the value
so that people other than the user cannot see it.
If the element is mutable, its value should be editable by the user. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value.
The value
attribute, if specified, must have a value that
contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.
The value sanitization algorithm is as follows: Strip line breaks from the value.
The following common input
element content
attributes, IDL attributes, and methods apply to the element: autocomplete
, inputmode
, maxlength
, minlength
, pattern
, placeholder
, readonly
, required
, and size
content attributes; selectionStart
, selectionEnd
, selectionDirection
, and value
IDL attributes; select()
, setRangeText()
, and setSelectionRange()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, list
, max
, min
, multiple
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the
element: checked
, files
, list
, valueAsDate
, and valueAsNumber
IDL attributes; stepDown()
and stepUp()
methods.
4.10.5.1.7. Date state (type=date
)
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
The input
element represents a control for setting the element’s value to a string representing a specific date.
date values represent a "floating" time and do not include time zone information. Care is needed when converting values of this type to or from date data types in JavaScript and other programming languages. In many cases, an implicit time-of-day and time zone are used to create a global ("incremental") time (an integer value that represents the offset from some arbitrary epoch time). Processing or conversion of these values, particularly across time zones, can change the value of the date itself. [TIMEZONE]
If the element is mutable, the user agent should allow the user to change the date represented by its value, as obtained by parsing a date from it. User agents must not allow the user to set the value to a non-empty string that is not a valid date string. If the user agent provides a user interface for selecting a date, then the value must be set to a valid date string representing the user’s selection. User agents should allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user agent cannot convert to a valid date string, the control is suffering from bad input.
See §4.10.1.8 Date, time, and number formats for a discussion of the difference between the input format and submission format for date, time, and number form controls, and the implementation notes regarding localization of form controls.
The value
attribute, if specified and not empty, must
have a value that is a valid date string.
The value sanitization algorithm is as follows: If the value of the element is not a valid date string, then set it to the empty string instead.
The min
attribute, if specified, must have a value that is
a valid date string. The max
attribute, if
specified, must have a value that is a valid date string.
The step
attribute is expressed in days. The step scale factor is 86,400,000 (which converts the days to milliseconds, which is the base unit of comparison for
the conversion algorithms below). The default step is 1 day.
When the element is suffering from a step mismatch, the user agent may round the element’s value to the nearest date for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a
number, given a string input, is as follows: If parsing a date from input results in an
error, then return an error; otherwise, return the number of milliseconds elapsed from midnight
UTC on the morning of 1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0Z
") to midnight UTC on the morning of the parsed date, ignoring leap seconds.
The algorithm to convert a number to a
string, given a number input, is as follows: Return a valid date string that represents the date that, in
UTC, is current input milliseconds after midnight UTC on the morning of
1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0Z
").
The algorithm to convert a string to a Date
object, given a string input, is as follows:
If parsing a date from input results
in an error, then return an error; otherwise, return a new Date
object representing midnight UTC on the morning of the parsed date.
The algorithm to convert a Date
object to a string, given a Date
object input, is as follows: Return a valid date string that
represents the date current at the time represented by input in the UTC time zone.
The following common input
element content
attributes, IDL attributes, and methods apply to the element: autocomplete
, list
, max
, min
, readonly
, required
, and step
content attributes; list
, value
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, stepDown()
, and stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, maxlength
, minlength
, multiple
, pattern
, placeholder
, size
, src
, and width
.
The following IDL attributes and methods do not apply to the
element: checked
, selectionStart
, selectionEnd
, and selectionDirection
IDL attributes; setRangeText()
, and setSelectionRange()
methods.
4.10.5.1.8. Month state (type=month
)
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
The input
element represents a control for setting the element’s value to a string representing a specific month.
If the element is mutable, the user agent should allow the user to change the month represented by its value, as obtained by parsing a month from it. User agents must not allow the user to set the value to a non-empty string that is not a valid month string. If the user agent provides a user interface for selecting a month, then the value must be set to a valid month string representing the user’s selection. User agents should allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user agent cannot convert to a valid month string, the control is suffering from bad input.
See §4.10.1.8 Date, time, and number formats for a discussion of the difference between the input format and submission format for date, time, and number form controls, and the implementation notes regarding localization of form controls.
The value
attribute, if specified and not empty, must
have a value that is a valid month string.
The value sanitization algorithm is as follows: If the value of the element is not a valid month string, then set it to the empty string instead.
The min
attribute, if specified, must have a value that is
a valid month string. The max
attribute, if
specified, must have a value that is a valid month string.
The step
attribute is expressed in months. The step scale factor is 1
(units of whole months are the base unit of comparison for the conversion algorithms below).
The default step is 1 month.
When the element is suffering from a step mismatch, the user agent may round the element’s value to the nearest month for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a number, given a string input, is as follows: If parsing a month from input results in an error, then return an error; otherwise, return the number of months between January 1970 and the parsed month.
The algorithm to convert a number to a string, given a number input, is as follows: Return a valid month string that represents the month that has input months between it and January 1970.
The algorithm to convert a string to a Date
object, given a string input, is as follows:
If parsing a month from input results in an error, then return an error; otherwise, return a
new Date
object representing midnight UTC on the morning of the first day of
the parsed month.
The algorithm to convert a Date
object to a string, given a Date
object input, is as follows: Return a valid month string that
represents the month current at the time represented by input in the UTC time zone.
The following common input
element content
attributes, IDL attributes, and methods apply to the element: autocomplete
, list
, max
, min
, readonly
, required
, and step
content attributes; list
, value
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, stepDown()
, and stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, maxlength
, minlength
, multiple
, pattern
, placeholder
, size
, src
, and width
.
The following IDL attributes and methods do not apply to the
element: checked
, files
, selectionStart
, selectionEnd
, and selectionDirection
IDL attributes; setRangeText()
, and setSelectionRange()
methods.
4.10.5.1.9. Week state (type=week
)
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
The input
element represents a control for setting the element’s value to a string representing a specific week beginning on a Monday, at midnight UTC.
If the element is mutable, the user agent should allow the user to change the week represented by its value, as obtained by parsing a week from it. User agents must not allow the user to set the value to a non-empty string that is not a valid week string. If the user agent provides a user interface for selecting a week, then the value must be set to a valid week string representing the user’s selection. User agents should allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user agent cannot convert to a valid week string, the control is suffering from bad input.
See §4.10.1.8 Date, time, and number formats for a discussion of the difference between the input format and submission format for date, time, and number form controls, and the implementation notes regarding localization of form controls.
The value
attribute, if specified and not empty, must
have a value that is a valid week string.
The value sanitization algorithm is as follows: If the value of the element is not a valid week string, then set it to the empty string instead.
The min
attribute, if specified, must have a value that is
a valid week string. The max
attribute, if
specified, must have a value that is a valid week string.
The step
attribute is expressed in weeks. The step scale factor is 604,800,000
(which converts the weeks to milliseconds, which is the base unit of comparison for the conversion
algorithms below). The default step is 1 week. The default step base is -259,200,000
(the start of week 1970-W01 which is the Monday 3 days before 1970-01-01).
When the element is suffering from a step mismatch, the user agent may round the element’s value to the nearest week for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a
number, given a string input, is as follows: If parsing a week string from input results in
an error, then return an error; otherwise, return the number of milliseconds elapsed from midnight
UTC on the morning of 1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0Z
") to midnight UTC on the morning of the Monday of the
parsed week, ignoring leap seconds.
The algorithm to convert a number to a
string, given a number input, is as follows: Return a valid week string that represents the week that, in
UTC, is current input milliseconds after midnight UTC on the morning of
1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0Z
").
The algorithm to convert a string to a Date
object, given a string input, is as follows:
If parsing a week from input results
in an error, then return an error; otherwise, return a new Date
object representing midnight UTC on the morning of the Monday of the
parsed week.
The algorithm to convert a Date
object to a string, given a Date
object input, is as follows: Return a valid week string that
represents the week current at the time represented by input in the UTC time zone.
The following common input
element content attributes, IDL attributes, and
methods apply to the element: autocomplete
, list
, max
, min
, readonly
, required
, and step
content attributes; list
, value
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, stepDown()
, and stepUp()
methods.
The value
IDL attribute is in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not apply to the
element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, maxlength
, minlength
, multiple
, pattern
, placeholder
, size
, src
, and width
.
The following IDL attributes and methods do not apply to the element: checked
, files
, selectionStart
, selectionEnd
, and selectionDirection
IDL attributes; setRangeText()
, and setSelectionRange()
methods.
4.10.5.1.10. Time state (type=time
)
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
The input
element represents a control for setting the element’s value to a string representing a specific time.
If the element is mutable, the user agent should allow the user to change the time represented by its value, as obtained by parsing a time from it. User agents must not allow the user to set the value to a non-empty string that is not a valid time string. If the user agent provides a user interface for selecting a time, then the value must be set to a valid time string representing the user’s selection. User agents should allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user agent cannot convert to a valid time string, the control is suffering from bad input.
See §4.10.1.8 Date, time, and number formats for a discussion of the difference between the input format and submission format for date, time, and number form controls, and the implementation notes regarding localization of form controls.
The value
attribute, if specified and not empty, must
have a value that is a valid time string.
The value sanitization algorithm is as follows: If the value of the element is not a valid time string, then set it to the empty string instead.
The form control has a periodic domain.
The min
attribute, if specified, must have a value that is
a valid time string. The max
attribute, if
specified, must have a value that is a valid time string.
The step
attribute is expressed in seconds. The step scale factor is 1000
(which converts the seconds to milliseconds, which is the base unit of comparison for the
conversion algorithms below). The default step is 60 seconds.
When the element is suffering from a step mismatch, the user agent may round the element’s value to the nearest time for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a number, given a string input, is as follows: If parsing a time from input results in an error, then return an error; otherwise, return the number of milliseconds elapsed from midnight to the parsed time on a day with no time changes.
The algorithm to convert a number to a string, given a number input, is as follows: Return a valid time string that represents the time that is input milliseconds after midnight on a day with no time changes.
The algorithm to convert a string to a Date
object, given a string input, is as follows:
If parsing a time from input results
in an error, then return an error; otherwise, return a new Date
object representing the parsed time in
UTC on 1970-01-01.
The algorithm to convert a Date
object to a string, given a Date
object input, is as follows: Return a valid time string that
represents the UTC time component that is represented by input.
The following common input
element content attributes, IDL attributes, and
methods apply to the element: autocomplete
, list
, max
, min
, readonly
, required
, and step
content attributes; list
, value
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, stepDown()
, and stepUp()
methods.
The value
IDL attribute is in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not apply to the
element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, maxlength
, minlength
, multiple
, pattern
, placeholder
, size
, src
, and width
.
The following IDL attributes and methods do not apply to the element: checked
, files
, selectionStart
, selectionEnd
, and selectionDirection
IDL attributes; setRangeText()
, and setSelectionRange()
methods.
4.10.5.1.11. Local Date and Time state (type=datetime-local
)
When an input
element’s type
attribute is in
the Local Date and Time state, the rules in
this section apply.
The input
element represents a control for setting the element’s value to a string representing a local date and time, with no time-zone offset
information.
If the element is mutable and the user agent provides a user interface for selecting a local date and time, then the value must be set to a valid normalized global date and time string representing the user’s selection. User agents should allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user agent cannot convert to a valid normalized global date and time string, the control is suffering from bad input.
See §4.10.1.8 Date, time, and number formats for a discussion of the difference between the input format and submission format for date, time, and number form controls, and the implementation notes regarding localization of form controls.
The value
attribute, if specified and not empty, must
have a value that is a valid floating date and time string.
The value sanitization algorithm is as follows: If the value of the element is a valid floating date and time string, then set it to a valid normalized floating date and time string representing the same date and time; otherwise, set it to the empty string instead.
The min
attribute, if specified, must have a value that is
a valid floating date and time string. The max
attribute, if specified, must have a value that is a valid floating date and time string.
The step
attribute is expressed in seconds. The step scale factor is 1000
(which converts the seconds to milliseconds, which is the base unit of comparison for the
conversion algorithms below). The default step is 60 seconds.
When the element is suffering from a step mismatch, the user agent may round the element’s value to the nearest floating date and time for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a
number, given a string input, is as follows: If parsing a date and time from input results in an error, then return an error; otherwise, return the number of
milliseconds elapsed from midnight on the morning of 1970-01-01 (the time represented by the value
"1970-01-01T00:00:00.0
") to the parsed floating date and time, ignoring leap seconds.
The algorithm to convert a number to a
string, given a number input, is as follows: Return a valid normalized floating date and time string that represents the date and time that is input milliseconds after midnight on the morning of 1970-01-01 (the time
represented by the value "1970-01-01T00:00:00.0
").
The following common input
element content
attributes, IDL attributes, and methods apply to the element: autocomplete
, list
, max
, min
, readonly
, required
, and step
content attributes; list
, value
, and valueAsNumber
IDL attributes; select()
, stepDown()
, and stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, maxlength
, minlength
, multiple
, pattern
, placeholder
, size
, src
, and width
.
The following IDL attributes and methods do not apply to the
element: checked
, files
, selectionStart
, selectionEnd
, selectionDirection
, and valueAsDate
IDL attributes; setRangeText()
, and setSelectionRange()
methods.
input
element with its type
attribute set to datetime-local
, and it then interprets the
given date and time in the time zone of the selected airport.
<fieldset> <legend>Destination</legend> <p><label>Airport: <input type=text name=to list=airports></label></p> <p><label>Departure time: <input type=datetime-local name=totime step=3600></label></p> </fieldset> <datalist id=airports> <option value=ATL label="Atlanta"> <option value=MEM label="Memphis"> <option value=LHR label="London Heathrow"> <option value=LAX label="Los Angeles"> <option value=FRA label="Frankfurt"> </datalist>
4.10.5.1.12. Number state (type=number
)
- Allowed ARIA role attribute values:
spinbutton
(default - do not set).- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
The input
element represents a control for setting the element’s value to a string representing a number.
If the element is mutable, the user agent should allow the user to change the number represented by its value, as obtained from applying the rules for parsing floating-point number values to it. User agents must not allow the user to set the value to a non-empty string that is not a valid floating-point number. If the user agent provides a user interface for selecting a number, then the value must be set to the best representation of the number representing the user’s selection as a floating-point number. User agents should allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user agent cannot convert to a valid floating-point number, the control is suffering from bad input.
See §4.10.1.8 Date, time, and number formats for a discussion of the difference between the input format and submission format for date, time, and number form controls, and the implementation notes regarding localization of form controls.
The value
attribute, if specified and not empty, must
have a value that is a valid floating-point number.
The value sanitization algorithm is as follows: If the value of the element is not a valid floating-point number, then set it to the empty string instead.
The min
attribute, if specified, must have a value that is
a valid floating-point number. The max
attribute,
if specified, must have a value that is a valid floating-point number.
The step scale factor is 1. The default step is 1 (allowing only integers to be selected by the user, unless the step base has a non-integer value).
When the element is suffering from a step mismatch, the user agent may round the element’s value to the nearest number for which the element would not suffer from a step mismatch. If there are two such numbers, user agents are encouraged to pick the one nearest positive infinity.
The algorithm to convert a string to a number, given a string input, is as follows: If applying the rules for parsing floating-point number values to input results in an error, then return an error; otherwise, return the resulting number.
The algorithm to convert a number to a string, given a number input, is as follows: Return a valid floating-point number that represents input.
The following common input
element content attributes, IDL attributes, and
methods apply to the element: autocomplete
, list
, max
, min
, placeholder
, readonly
, required
, and step
content attributes; list
, value
, and valueAsNumber
IDL attributes; select()
, stepDown()
, and stepUp()
methods.
The value
IDL attribute is in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not apply to the
element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, maxlength
, minlength
, multiple
, pattern
, size
, src
, and width
.
The following IDL attributes and methods do not apply to the element: checked
, files
, selectionStart
, selectionEnd
, selectionDirection
, and valueAsDate
IDL attributes; setRangeText()
, and setSelectionRange()
methods.
<label>How much do you want to charge? $<input type=number min=0 step=0.01 name=price></label>
As described above, a user agent might support numeric input in the user’s local format, converting it to the format required for submission as described above. This might include handling grouping separators (as in "872,000,000,000") and various decimal separators (such as "3,99" vs "3.99") or using local digits (such as those in Arabic, Devanagari, Persian, and Thai).
The type=number
state is not appropriate for input that
happens to only consist of numbers but isn’t strictly speaking a number. For example, it would be
inappropriate for credit card numbers or US postal codes. A simple way of determining whether to
use type=number
is to consider whether it would make sense for the input
control to have a spinbox interface (e.g., with "up" and "down" arrows). Getting a credit card
number wrong by 1 in the last digit isn’t a minor mistake, it’s as wrong as getting every digit
incorrect. So it would not make sense for the user to select a credit card number using "up" and
"down" buttons. When a spinbox interface is not appropriate, type=text
is
probably the right choice (possibly with a pattern
attribute).
4.10.5.1.13. Range state (type=range
)
-
Allowed ARIA role attribute values:
-
slider
(default - do not set). -
Allowed ARIA state and property attributes:
-
Any
aria-*
attributes applicable to the allowed roles.
When an input
element’s type
attribute is in the Range state, the rules in this section apply.
The input
element represents a control for setting the element’s value to a string representing a number, but with the caveat that the exact
value is not important, letting user agents provide a simpler interface than they do for the Number state.
If the element is mutable, the user agent should allow the user to change the number represented by its value, as obtained from applying the rules for parsing floating-point number values to it. User agents must not allow the user to set the value to a string that is not a valid floating-point number. If the user agent provides a user interface for selecting a number, then the value must be set to a best representation of the number representing the user’s selection as a floating-point number. User agents must not allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user agent cannot convert to a valid floating-point number, the control is suffering from bad input.
The value
attribute, if specified, must have a value that is a valid floating-point number.
The value sanitization algorithm is as follows: If the value of the element is not a valid floating-point number, then set it to the best representation, as a floating-point number, of the default value.
The default value is the minimum plus half the difference between the minimum and the maximum, unless the maximum is less than the minimum, in which case the default value is the minimum.
When the element is suffering from an underflow, the user agent must set the element’s value to the best representation, as a floating-point number, of the minimum.
When the element is suffering from an overflow, if the maximum is not less than the minimum, the user agent must set the element’s value to a valid floating-point number that represents the maximum.
When the element is suffering from a step mismatch, the user agent must round the element’s value to the nearest number for which the element would not suffer from a step mismatch, and which is greater than or equal to the minimum, and, if the maximum is not less than the minimum, which is less than or equal to the maximum, if there is a number that matches these constraints. If two numbers match these constraints, then user agents must use the one nearest to positive infinity.
For example, the markup <input type="range" min=0 max=100 step=20 value=50>
results in a range control whose initial value is 60.
list
attribute. This could be useful if there are values along the full range of the control that are
especially important, such as preconfigured light levels or typical speed limits in a range
control used as a speed control. The following markup fragment:
<input type="range" min="-100" max="100" value="0" step="10" name="power" list="powers"> <datalist id="powers"> <option value="0"> <option value="-30"> <option value="30"> <option value="++50"> </datalist>
...with the following style sheet applied:
input { height: 75px; width: 49px; background: #D5CCBB; color: black; }
...might render as:
Note how the user agent determined the orientation of the control from the ratio of the
style-sheet-specified height and width properties. The colors were similarly derived from the
style sheet. The tick marks, however, were derived from the markup. In particular, the step
attribute has not affected the placement of tick marks, the user agent deciding
to only use the author-specified completion values and then adding longer tick marks at the
extremes.
Note also how the invalid value ++50
was completely ignored.
<input name=x type=range min=100 max=700 step=9.09090909 value=509.090909>
A user agent could display in a variety of ways, for instance:
Or, alternatively, for instance:
The user agent could pick which one to display based on the dimensions given in the style sheet. This would allow it to maintain the same resolution for the tick marks, despite the differences in width.
<input type="range" name="a" list="a-values"> <datalist id="a-values"> <option value="10" label="Low"> <option value="90" label="High"> </datalist>
With styles that make the control draw vertically, it might look as follows:
In this state, the range and step constraints are enforced even during user input, and there is no way to set the value to the empty string.
The min
attribute, if specified, must have a value that is a valid floating-point number. The default minimum is 0. The max
attribute,
if specified, must have a value that is a valid floating-point number. The default maximum is 100.
The step scale factor is 1. The default step is 1 (allowing only integers, unless
the min
attribute has a non-integer value).
The algorithm to convert a string to a number, given a string input, is as follows: If applying the rules for parsing floating-point number values to input results in an error, then return an error; otherwise, return the resulting number.
The algorithm to convert a number to a string, given a number input, is as follows: Return the best representation, as a floating-point number, of input.
input
element content attributes, IDL attributes, and
methods apply to the element: autocomplete
, list
, max
, min
, and step
content attributes; list
, value
, and valueAsNumber
IDL attributes; stepDown()
and stepUp()
methods.
The value
IDL attribute is in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not apply to the
element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, maxlength
, minlength
, multiple
, pattern
, placeholder
, readonly
, required
, size
, src
, and width
.
The following IDL attributes and methods do not apply to the element: checked
, files
, selectionStart
, selectionEnd
, selectionDirection
, and valueAsDate
IDL attributes; select()
, setRangeText()
, and setSelectionRange()
methods.
4.10.5.1.14. Color state (type=color
)
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
The input
element represents a color well control, for setting the
element’s value to a string representing a simple
color.
In this state, there is always a color picked, and there is no way to set the value to the empty string.
If the element is mutable, the user agent should allow the user to change the color represented by its value, as obtained from applying the rules for parsing simple color values to it. User agents must not allow the user to set the value to a string that is not a valid lowercase simple color. If the user agent provides a user interface for selecting a color, then the value must be set to the result of using the rules for serializing simple color values to the user’s selection. User agents must not allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user agent cannot convert to a valid lowercase simple color, the control is suffering from bad input.
The value
attribute, if specified and not empty, must
have a value that is a valid simple color.
The value sanitization algorithm is as follows: If the value of the element is a valid simple color, then
set it to the value of the element converted to ASCII
lowercase; otherwise, set it to the string "#000000
".
The following common input
element content attributes and IDL attributes apply to the element: autocomplete
and list
content attributes; list
and value
IDL attributes; select()
method.
The value
IDL attribute is in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not apply to the
element: accept
, alt
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, max
, maxlength
, min
, minlength
, multiple
, pattern
, placeholder
, readonly
, required
, size
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the element: checked
, files
, selectionStart
, selectionEnd
, selectionDirection
, valueAsDate
, and valueAsNumber
IDL attributes; setRangeText()
, setSelectionRange()
, stepDown()
, and stepUp()
methods.
4.10.5.1.15. Checkbox state (type=checkbox
)
- Allowed ARIA role attribute values:
checkbox
(default - do not set) ormenuitemcheckbox
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
The input
element represents a two-state control that represents the
element’s checkedness state. If the element’s checkedness state is true, the control represents a positive
selection, and if it is false, a negative selection. If the element’s indeterminate
IDL attribute is set to true, then the
control’s selection should be obscured as if the control was in a third, indeterminate, state.
The control is never a true tri-state control, even if the element’s indeterminate
IDL attribute is set to true. The indeterminate
IDL attribute only gives the appearance of a
third state.
If the element is mutable, then: The pre-click
activation steps consist of setting the element’s checkedness to its opposite value (i.e., true if it is false,
false if it is true), and of setting the element’s indeterminate
IDL attribute to false. The canceled
activation steps consist of setting the checkedness and the element’s indeterminate
IDL attribute back to the values they had
before the pre-click activation steps were run. The activation behavior is to fire a simple event that bubbles named input
at the element and then fire a simple event that bubbles named change
at the element.
If the element is not mutable, it has no activation behavior.
Constraint validation: If the element is required and its checkedness is false, then the element is suffering from being missing.
- input .
indeterminate
[ = value ] -
When set, overrides the rendering of checkbox controls so that the current value is not visible.
The following common input
element content attributes and IDL attributes apply to the element: checked
, and required
content attributes; checked
and value
IDL attributes.
The value
IDL attribute is in mode default/on.
The input
and change
events apply.
The following content attributes must not be specified and do not apply to the
element: accept
, alt
, autocomplete
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, list
, max
, maxlength
, min
, minlength
, multiple
, pattern
, placeholder
, readonly
, size
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the element: files
, list
, selectionStart
, selectionEnd
, selectionDirection
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, setRangeText()
, setSelectionRange()
, stepDown()
, and stepUp()
methods.
4.10.5.1.16. Radio Button state (type=radio
)
- Allowed ARIA role attribute values:
radio
(default - do not set) ormenuitemradio
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
When an input
element’s type
attribute is in
the Radio Button state, the rules in this section
apply.
The input
element represents a control that, when used in conjunction
with other input
elements, forms a radio button group in which only one
control can have its checkedness state set to true. If
the element’s checkedness state is true, the control
represents the selected control in the group, and if it is false, it indicates a control in the
group that is not selected.
The radio button group that contains an input
element a also contains all the other input
elements b that fulfill all
of the following conditions:
- The
input
element b’stype
attribute is in the Radio Button state. - Either a and b have the same form owner, or they both have no form owner.
- Both a and b are in the same home subtree.
- They both have a
name
attribute, theirname
attributes are not empty, and the value of a’sname
attribute is a compatibility caseless match for the value of b’sname
attribute.
A document must not contain an input
element whose radio button group contains only that element.
When any of the following phenomena occur, if the element’s checkedness state is true after the occurrence, the checkedness state of all the other elements in the same radio button group must be set to false:
- The element’s checkedness state is set to true (for whatever reason).
- The element’s
name
attribute is set, changed, or removed. - The element’s form owner changes.
- A type change is signalled for the element.
If the element R is mutable, then: The pre-click activation steps for R consist of getting a reference to the
element in R’s radio button group that has its checkedness set to true, if any, and then setting R’s checkedness to true. The canceled
activation steps for R consist of checking if the element to which a reference
was obtained in the pre-click activation steps, if any, is still in what is now R’s radio button group, if it still has one, and if so, setting that
element’s checkedness to true; or else, if there was no
such element, or that element is no longer in R’s radio button group, or
if R no longer has a radio button group, setting R’s checkedness to false. The activation behavior for R is to fire a simple event that bubbles named input
at R and then fire a simple event that bubbles named change
at R.
If the element is not mutable, it has no activation behavior.
Constraint validation: If an element in the radio button group is required, and all of the input
elements in the radio button group have a checkedness that is
false, then the element is suffering from being missing.
If none of the radio buttons in a radio button group are checked when they are inserted into the document, then they will all be initially unchecked in the interface, until such time as one of them is checked (either by the user or by script).
The following common input
element content attributes and IDL attributes apply to the element: checked
and required
content attributes; checked
and value
IDL attributes.
The value
IDL attribute is in mode default/on.
The input
and change
events apply.
The following content attributes must not be specified and do not apply to the
element: accept
, alt
, autocomplete
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, list
, max
, maxlength
, min
, minlength
, multiple
, pattern
, placeholder
, readonly
, size
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the element: files
, list
, selectionStart
, selectionEnd
, selectionDirection
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, setRangeText()
, setSelectionRange()
, stepDown()
, and stepUp()
methods.
4.10.5.1.17. File Upload state (type=file
)
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
When an input
element’s type
attribute is in
the File Upload state, the rules in this section
apply.
The input
element represents a list of selected files, each file consisting of a file
name, a file type, and a file body (the contents of the file).
File names must not contain path components, even in the case that a user has selected an entire directory hierarchy or multiple files with the same name from different directories. Path components, for the purposes of the File Upload state, are those parts of file names that are separated by U+005C REVERSE SOLIDUS character (\) characters.
Unless the multiple
attribute is set, there must be
no more than one file in the list of selected
files.
If the element is mutable, then the element’s activation behavior is to run the following steps:
- If the algorithm is not allowed to show a popup, then abort these steps without doing anything else.
- Return, but continue running these steps in parallel.
- Optionally, wait until any prior execution of this algorithm has terminated.
- Display a prompt to the user requesting that the user specify some files. If the
multiple
attribute is not set, there must be no more than one file selected; otherwise, any number may be selected. Files can be from the filesystem or created on the fly, e.g., a picture taken from a camera connected to the user’s device. - Wait for the user to have made their selection.
- Queue a task to first update the element’s selected files so that it represents the user’s
selection, then fire a simple event that bubbles named
input
at theinput
element, and finally fire a simple event that bubbles namedchange
at theinput
element.
If the element is mutable, the user agent should allow the
user to change the files on the list in other ways also, e.g., adding or removing files by
drag-and-drop. When the user does so, the user agent must queue a task to first
update the element’s selected files so that
it represents the user’s new selection, then fire a simple event that bubbles named input
at the input
element, and finally fire a simple event that bubbles named change
at the input
element.
If the element is not mutable, it has no activation behavior and the user agent must not allow the user to change the element’s selection.
Constraint validation: If the element is required and the list of selected files is empty, then the element is suffering from being missing.
The accept
attribute may be specified to
provide user agents with a hint of what file types will be accepted.
If specified, the attribute must consist of a set of comma-separated tokens, each of which must be an ASCII case-insensitive match for one of the following:
- The string "
audio/*
" - Indicates that sound files are accepted.
- The string "
video/*
" - Indicates that video files are accepted.
- The string "
image/*
" - Indicates that image files are accepted.
- A valid MIME type with no parameters
- Indicates that files of the specified type are accepted.
- A string whose first character is a U+002E FULL STOP character (.)
- Indicates that files with the specified file extension are accepted.
The tokens must not be ASCII case-insensitive matches for any of the other tokens (i.e., duplicates are not allowed). To obtain the list of tokens from the attribute, the user agent must split the attribute value on commas.
User agents may use the value of this attribute to display a more appropriate user interface
than a generic file picker. For instance, given the value image/*
, a user
agent could offer the user the option of using a local camera or selecting a photograph from their
photo collection; given the value audio/*
, a user agent could offer the user
the option of recording a clip using a headset microphone.
Authors are encouraged to specify both any MIME types and any corresponding extensions when looking for data in a specific format.
<input type="file" accept=".doc,.docx,.xml,application/msword,application/vnd.openxmlformats-officedocument.wordprocessingml.document">
On platforms that only use file extensions to describe file types, the extensions listed here can be used to filter the allowed documents, while the MIME types can be used with the system’s type registration table (mapping MIME types to extensions used by the system), if any, to determine any other extensions to allow. Similarly, on a system that does not have file names or extensions but labels documents with MIME types internally, the MIME types can be used to pick the allowed files, while the extensions can be used if the system has an extension registration table that maps known extensions to MIME types used by the system.
Extensions tend to be ambiguous (e.g., there are an untold number of formats
that use the ".dat
" extension, and users can typically quite easily rename
their files to have a ".doc
" extension even if they are not Microsoft Word
documents), and MIME types tend to be unreliable (e.g., many formats have no formally registered
types, and many formats are in practice labeled using a number of different MIME types). Authors
are reminded that, as usual, data received from a client should be treated with caution, as it may
not be in an expected format even if the user is not hostile and the user agent fully obeyed the accept
attribute’s requirements.
value
IDL attribute prefixes
the file name with the string "C:\fakepath\
". Some legacy user agents
actually included the full path (which was a security vulnerability). As a result of this,
obtaining the file name from the value
IDL attribute in a
backwards-compatible way is non-trivial. The following function extracts the file name in a
suitably compatible manner:
function extractFilename(path) { if (path.substr(0, 12) == "C:\\fakepath\\") return path.substr(12); // modern browser var x; x = path.lastIndexOf('/'); if (x >= 0) // Unix-based path return path.substr(x+1); x = path.lastIndexOf('\\'); if (x >= 0) // Windows-based path return path.substr(x+1); return path; // just the file name }
This can be used as follows:
<p><input type=file name=image onchange="updateFilename(this.value)"></p> <p>The name of the file you picked is: <span id="filename">(none)</span></p> <script> function updateFilename(path) { var name = extractFilename(path); document.getElementById('filename').textContent = name; } </script>
input
element content attributes and IDL attributes apply to the element: accept
, multiple
, and required
content attributes; files
and value
IDL attributes; select()
method.
The value
IDL attribute is in mode filename.
The input
and change
events apply.
The following content attributes must not be specified and do not apply to the
element: alt
, autocomplete
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, list
, max
, maxlength
, min
, minlength
, pattern
, placeholder
, readonly
, size
, src
, step
, and width
.
The element’s value
attribute must be omitted.
The following IDL attributes and methods do not apply to the element: checked
, list
, selectionStart
, selectionEnd
, selectionDirection
, valueAsDate
, and valueAsNumber
IDL attributes; setRangeText()
, setSelectionRange()
, stepDown()
, and stepUp()
methods.
4.10.5.1.18. Submit Button state (type=submit
)
- Allowed ARIA role attribute values:
button
(default - do not set).- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
When an input
element’s type
attribute is in
the submit button state, the rules in this section
apply.
The input
element represents a button that, when activated, submits
the form. If the element has a value
attribute, the button’s label must be the value of that attribute; otherwise, it must be an
implementation-defined string that means "Submit" or some such. The element is a button, specifically a submit
button.
Since the default label is implementation-defined, and the width of the button typically depends on the button’s label, the button’s width can leak a few bits of fingerprintable information. These bits are likely to be strongly correlated to the identity of the user agent and the user’s locale.
If the element is mutable, then the element’s activation behavior is as follows: if the element has a form owner,
and the element’s node document is fully active, submit the form owner from the input
element; otherwise, do nothing.
If the element is not mutable, it has no activation behavior.
The formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
attributes are attributes for form
submission.
The formnovalidate
attribute can be
used to make submit buttons that do not trigger the constraint validation.
The following common input
element content attributes and IDL attributes apply to the element: formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
content attributes; value
IDL attribute.
The value
IDL attribute is in mode default.
The following content attributes must not be specified and do not apply to the
element: accept
, alt
, autocomplete
, checked
, dirname
, height
, inputmode
, list
, max
, maxlength
, min
, minlength
, multiple
, pattern
, placeholder
, readonly
, required
, size
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the element: checked
, files
, list
, selectionStart
, selectionEnd
, selectionDirection
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, setRangeText()
, setSelectionRange()
, stepDown()
, and stepUp()
methods.
The input
and change
events do not apply.
4.10.5.1.19. Image Button state (type=image
)
- Allowed ARIA role attribute values:
button
(default - do not set),link
,menuitem
,menuitemcheckbox
,menuitemradio
orradio
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
When an input
element’s type
attribute is in
the image button state, the rules in this section
apply.
The input
element represents either an image from which a user can
select a coordinate and submit the form, or alternatively a button from which the user can submit
the form. The element is a button, specifically a submit button.
The coordinate is sent to the server during form submission by sending two entries for the element, derived from the name
of the control but with ".x
" and ".y
" appended to the
name with the x and y components of the coordinate
respectively.
The image is given by the src
attribute. The src
attribute must be present, and must contain a valid
non-empty URL potentially surrounded by spaces referencing a non-interactive, optionally
animated, image resource that is neither paged nor scripted.
When any of the these events occur
- the
input
element’stype
attribute is first set to the Image Button state (possibly when the element is first created), and thesrc
attribute is present - the
input
element’stype
attribute is changed back to the Image Button state, and thesrc
attribute is present, and its value has changed since the last time thetype
attribute was in the Image Button state - the
input
element’stype
attribute is in the Image Button state, and thesrc
attribute is set or changed
then unless the user agent cannot support images, or its support for images has been disabled,
or the user agent only fetches images on demand, or the src
attribute’s value is the empty string, the user agent must parse the value of the src
attribute value, relative to the element’s node document, and if that is successful, run these substeps:
- Let request be a new request whose URL is the resulting URL string, client is the element’s node document’s
Window
object’s environment settings object, type is "image
", destination is "subresource
", omit-Origin
-header flag is set, credentials mode is "include
", and whose use-URL-credentials flag is set. - Fetch request.
Fetching the image must delay the load event of the element’s node document until the task that is queued by the networking task source once the resource has been fetched (defined below) has been run.
If the image was successfully obtained, with no network errors, and the image’s type is a supported image type, and the image is a valid image of that type, then the image is said to be available. If this is true before the image is completely downloaded, each task that is queued by the networking task source while the image is being fetched must update the presentation of the image appropriately.
The user agent should apply the image sniffing rules to determine the type of the image, with the image’s associated Content-Type headers giving the official type. If these rules are not applied, then the type of the image must be the type given by the image’s associated Content-Type headers.
User agents must not support non-image resources with the input
element. User
agents must not run executable code embedded in the image resource. User agents must only display
the first page of a multipage resource. User agents must not allow the resource to act in an
interactive fashion, but should honor any animation in the resource.
The task that is queued by the networking task source once the resource has been fetched, must, if the
download was successful and the image is available, queue a task to fire a simple event named load
at the input
element; and otherwise, if the fetching
process fails without a response from the remote server, or completes but the image is not a valid
or supported image, queue a task to fire a simple event named error
on the input
element.
The alt
attribute provides the textual label for
the button for users and user agents who cannot use the image. The alt
attribute must be present, and must contain a non-empty string
giving the label that would be appropriate for an equivalent button if the image was
unavailable.
The input
element supports dimension attributes.
If the src
attribute is set, and the image is available and the user agent is configured to display that image,
then: The element represents a control for selecting a coordinate from the image specified by the src
attribute; if the element is mutable, the user agent should allow the user to select this coordinate, and the element’s activation
behavior is as follows: if the element has a form owner, and the element’s node document is fully active, take the user’s selected coordinate, and submit the input
element’s form owner from the input
element. If the user activates the control without explicitly
selecting a coordinate, then the coordinate (0,0) must be assumed.
Otherwise, the element represents a submit button whose label is given by the
value of the alt
attribute; if the element is mutable, then the element’s activation behavior is as
follows: if the element has a form owner, and the element’s node document is fully active, set the selected
coordinate to (0,0), and submit the input
element’s form owner from the input
element.
In either case, if the element is mutable but has no form owner or the element’s node document is not fully active, then its activation behavior must be to do nothing. If the element is not mutable, it has no activation behavior.
The selected coordinate must consist of an x-component and a y-component. The coordinates represent the position relative to the edge of the image, with the coordinate space having the positive x direction to the right, and the positive y direction downwards.
The x-component must be a valid integer representing a number x in the range -(borderleft+paddingleft) ≤ x ≤ width+borderright+paddingright, where width is the rendered width of the image, borderleft is the width of the border on the left of the image, paddingleft is the width of the padding on the left of the image, borderright is the width of the border on the right of the image, and paddingright is the width of the padding on the right of the image, with all dimensions given in CSS pixels.
The y-component must be a valid integer representing a number y in the range -(bordertop+paddingtop) ≤ y ≤ height+borderbottom+paddingbottom, where height is the rendered height of the image, bordertop is the width of the border above the image, paddingtop is the width of the padding above the image, borderbottom is the width of the border below the image, and paddingbottom is the width of the padding below the image, with all dimensions given in CSS pixels.
Where a border or padding is missing, its width is zero CSS pixels.
The formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
attributes are attributes for form
submission.
- image .
width
[ = value ]- image .
height
[ = value ] - image .
-
These attributes return the actual rendered dimensions of the image, or zero if the dimensions are not known.
They can be set, to change the corresponding content attributes.
The following common input
element content attributes and IDL attributes apply to the element: alt
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, src
, and width
content attributes; value
IDL attribute.
The value
IDL attribute is in mode default.
The following content attributes must not be specified and do not apply to the
element: accept
, autocomplete
, checked
, dirname
, inputmode
, list
, max
, maxlength
, min
, minlength
, multiple
, pattern
, placeholder
, readonly
, required
, size
, and step
.
The element’s value
attribute must be omitted.
The following IDL attributes and methods do not apply to the element: checked
, files
, list
, selectionStart
, selectionEnd
, selectionDirection
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, setRangeText()
, setSelectionRange()
, stepDown()
, and stepUp()
methods.
The input
and change
events do not apply.
Many aspects of this state’s behavior are similar to the behavior of the img
element. Readers are encouraged to read that section, where many of the same
requirements are described in more detail.
<form action="process.cgi"> <input type=image src=map.png name=where alt="Show location list"> </form>
If the user clicked on the image at coordinate (127,40) then the URL used to submit the form
would be "process.cgi?where.x=127&where.y=40
".
(In this example, it’s assumed that for users who don’t see the map, and who instead just see a button labeled "Show location list", clicking the button will cause the server to show a list of locations to pick from instead of the map.)
4.10.5.1.20. Reset Button state (type=reset
)
- Allowed ARIA role attribute values:
button
(default - do not set).- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
When an input
element’s type
attribute is in
the Reset Button state, the rules in this section
apply.
The input
element represents a button that, when activated, resets
the form. If the element has a value
attribute, the button’s label must be the value of that attribute; otherwise, it must be an
implementation-defined string that means "Reset" or some such. The element is a button.
Since the default label is implementation-defined, and the width of the button typically depends on the button’s label, the button’s width can leak a few bits of fingerprintable information. These bits are likely to be strongly correlated to the identity of the user agent and the user’s locale.
If the element is mutable, then the element’s activation behavior, if the element has a form owner and the element’s node document is fully active, is to reset the form owner; otherwise, it is to do nothing.
If the element is not mutable, it has no activation behavior.
Constraint validation: The element is barred from constraint validation.
The value
IDL attribute applies to this element and is in mode default.
The following content attributes must not be specified and do not apply to the
element: accept
, alt
, autocomplete
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, list
, max
, maxlength
, min
, minlength
, multiple
, pattern
, placeholder
, readonly
, required
, size
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the element: checked
, files
, list
, selectionStart
, selectionEnd
, selectionDirection
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, setRangeText()
, setSelectionRange()
, stepDown()
, and stepUp()
methods.
The input
and change
events do not apply.
4.10.5.1.21. Button state (type=button
)
- Allowed ARIA role attribute values:
button
(default - do not set),link
,menuitem
,menuitemcheckbox
,menuitemradio
orradio
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
The input
element represents a button with no default behavior. A
label for the button must be provided in the value
attribute, though it may be the empty string. If the element has a value
attribute, the button’s label must be the value of that
attribute; otherwise, it must be the empty string. The element is a button.
If the element is mutable, the element’s activation behavior is to do nothing.
If the element is not mutable, it has no activation behavior.
Constraint validation: The element is barred from constraint validation.
The value
IDL attribute applies to this element and is in mode default.
The following content attributes must not be specified and do not apply to the
element: accept
, alt
, autocomplete
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, inputmode
, list
, max
, maxlength
, min
, minlength
, multiple
, pattern
, placeholder
, readonly
, required
, size
, src
, step
, and width
.
The following IDL attributes and methods do not apply to the element: checked
, files
, list
, selectionStart
, selectionEnd
, selectionDirection
, valueAsDate
, and valueAsNumber
IDL attributes; select()
, setRangeText()
, setSelectionRange()
, stepDown()
, and stepUp()
methods.
The input
and change
events do not apply.
4.10.5.2. Implementation notes regarding localization of form controls
This section is non-normative.
The formats shown to the user in date, time, and number controls is independent of the format used for form submission.
Browsers are encouraged to use user interfaces that present dates, times, and numbers according
to the conventions of either the locale implied by the input
element’s language or the user’s preferred locale. Using the page’s locale will ensure
consistency with page-provided data.
For example, it would be confusing to users if an American English page claimed that a Cirque De Soleil show was going to be showing on 02/03, but their browser, configured to use the British English locale, only showed the date 03/02 in the ticket purchase date picker. Using the page’s locale would at least ensure that the date was presented in the same format everywhere. (There’s still a risk that the user would end up arriving a month late, of course, but there’s only so much that can be done about such cultural differences...)
4.10.5.3. Common input
element attributes
These attributes only apply to an input
element if its type
attribute is in a state whose definition
declares that the attribute applies. When an attribute doesn’t apply to an input
element, user agents must ignore the attribute, regardless of the requirements and definitions below.
4.10.5.3.1. The maxlength
and minlength
attributes
The maxlength
attribute, when it applies, is a form control maxlength
attribute controlled by the input
element’s dirty value flag.
The minlength
attribute, when it applies, is a form control minlength
attribute controlled by the input
element’s dirty value flag.
If the input
element has a maximum allowed value length, then the code-unit length of the value of the element’s value
attribute must be equal to or less than the element’s maximum allowed value length.
<label>What are you doing? <input name=status maxlength=140></label>
<p><label>Username: <input name=u required></label> <p><label>Password: <input name=p required minlength=12></label>
4.10.5.3.2. The size
attribute
The size
attribute gives the number of
characters that, in a visual rendering, the user agent is to allow the user to see while editing
the element’s value.
The size
attribute, if specified, must have a value that
is a valid non-negative integer greater than zero.
If the attribute is present, then its value must be parsed using the rules for parsing non-negative integers, and if the result is a number greater than zero, then the user agent should ensure that at least that many characters are visible.
The size
IDL attribute is limited to only
non-negative numbers greater than zero and has a default value of 20.
4.10.5.3.3. The readonly
attribute
The readonly
attribute is a boolean
attribute that controls whether or not the user can edit the form control. When specified, the element is not mutable.
Constraint validation: If the readonly
attribute is specified on an input
element, the element is barred from constraint validation.
The difference between disabled
and readonly
is that read-only controls are still focusable, so the
user can still select the text and interact with it, whereas disabled controls are entirely
non-interactive. (For this reason, only text controls can be made read-only: it wouldn’t make
sense for checkboxes or buttons, for instances.)
<form action="products.cgi" method="post" enctype="multipart/form-data"> <table> <tr> <th> Product ID <th> Product name <th> Price <th> Action <tr> <td> <input readonly="readonly" name="1.pid" value="H412"> <td> <input required="required" name="1.pname" value="Floor lamp Ulke"> <td> $<input required="required" type="number" min="0" step="0.01" name="1.pprice" value="49.99"> <td> <button formnovalidate="formnovalidate" name="action" value="delete:1">Delete</button> <tr> <td> <input readonly="readonly" name="2.pid" value="FG28"> <td> <input required="required" name="2.pname" value="Table lamp Ulke"> <td> $<input required="required" type="number" min="0" step="0.01" name="2.pprice" value="24.99"> <td> <button formnovalidate="formnovalidate" name="action" value="delete:2">Delete</button> <tr> <td> <input required="required" name="3.pid" value="" pattern="[A-Z0-9]+"> <td> <input required="required" name="3.pname" value=""> <td> $<input required="required" type="number" min="0" step="0.01" name="3.pprice" value=""> <td> <button formnovalidate="formnovalidate" name="action" value="delete:3">Delete</button> </table> <p> <button formnovalidate="formnovalidate" name="action" value="add">Add</button> </p> <p> <button name="action" value="update">Save</button> </p> </form>
4.10.5.3.4. The required
attribute
The required
attribute is a boolean
attribute. When specified, the element is required.
Constraint validation: If the element is required, and its value
IDL attribute applies and is in the mode value, and the element is mutable, and the element’s value is the empty string, then the element is suffering
from being missing.
<h1>Create new account</h1> <form action="/newaccount" method=post oninput="up2.setCustomValidity(up2.value != up.value ? 'Passwords do not match.' : '')"> <p> <label for="username">E-mail address:</label> <input id="username" type=email required name=un> <p> <label for="password1">Password:</label> <input id="password1" type=password required name=up> <p> <label for="password2">Confirm password:</label> <input id="password2" type=password name=up2> <p> <input type=submit value="Create account"> </form>
required
attribute is
satisfied if any of the radio buttons in the group is
selected. Thus, in the following example, any of the radio buttons can be checked, not just the
one marked as required:
<fieldset> <legend>Did the movie pass the Bechdel test?</legend> <p><label><input type="radio" name="bechdel" value="no-characters"> No, there are not even two female characters in the movie. </label> <p><label><input type="radio" name="bechdel" value="no-names"> No, the female characters never talk to each other. </label> <p><label><input type="radio" name="bechdel" value="no-topic"> No, when female characters talk to each other it’s always about a male character. </label> <p><label><input type="radio" name="bechdel" value="yes" required> Yes. </label> <p><label><input type="radio" name="bechdel" value="unknown"> I don’t know. </label> </fieldset>
To avoid confusion as to whether a radio button group is required or not, authors are encouraged to specify the attribute on all the radio buttons in a group. Indeed, in general, authors are encouraged to avoid having radio button groups that do not have any initially checked controls in the first place, as this is a state that the user cannot return to, and is therefore generally considered a poor user interface.
4.10.5.3.5. The multiple
attribute
The multiple
attribute is a boolean
attribute that indicates whether the user is to be allowed to specify more than one
value.
<label>Cc: <input type=email multiple name=cc></label>
If the user had, amongst many friends in their user contacts database, two friends "Arthur Dent" (with address "art@example.net") and "Adam Josh" (with address "adamjosh@example.net"), then, after the user has typed "a", the user agent might suggest these two e-mail addresses to the user.
The page could also link in the user’s contacts database from the site:
<label>Cc: <input type=email multiple name=cc list=contacts></label> ... <datalist id="contacts"> <option value="hedral@damowmow.com"> <option value="pillar@example.com"> <option value="astrophy@cute.example"> <option value="astronomy@science.example.org"> </datalist>
Suppose the user had entered "bob@example.net" into this text field, and then started typing a
second e-mail address starting with "a". The user agent might show both the two friends mentioned
earlier, as well as the "astrophy" and "astronomy" values given in the datalist
element.
<label>Attachments: <input type=file multiple name=att></label>
4.10.5.3.6. The pattern
attribute
The pattern
attribute specifies a regular
expression against which the control’s value, or, when the multiple
attribute applies and is set, the control’s values, are to be checked.
If specified, the attribute’s value must match the JavaScript Pattern production. [ECMA-262]
If an input
element has a pattern
attribute specified, and the attribute’s value, when compiled as a JavaScript regular expression
with only the "u
" flag specified, compiles successfully, then the resulting regular expression is the element’s compiled pattern regular expression. If the element has no such attribute, or if the
value doesn’t compile successfully, then the element has no compiled pattern regular
expression. [ECMA-262]
If the value doesn’t compile successfully, user agents are encouraged to log this fact in a developer console, to aid debugging.
Constraint validation: If the element’s value is not the empty string, and either the element’s multiple
attribute is not specified or it does not apply to the input
element given its type
attribute’s current state, and the element has a compiled pattern regular expression but that regular expression does not match the
entirety of the element’s value, then the element is suffering from a pattern mismatch.
Constraint validation: If the element’s value is not the empty string, and the element’s multiple
attribute is specified and applies to the input
element, and the element has
a compiled pattern regular expression but that regular expression does not match the
entirety of each of the element’s values, then the
element is suffering from a pattern mismatch.
The compiled pattern regular expression, when matched against a string, must have its start anchored to the start of the string and its end anchored to the end of the string.
This implies that the regular expression language used for this attribute is the
same as that used in JavaScript, except that the pattern
attribute is matched against the entire value, not just any subset (somewhat as if it implied a ^(?:
at the start of the pattern and a )$
at the
end).
When an input
element has a pattern
attribute specified, authors should provide a description of the pattern in text near the
control. Authors may also include a title
attribute to give a description of the pattern. User agents may use
the contents of this attribute, if it is present, when informing the
user that the pattern is not matched, or at any other suitable time,
such as in a tooltip or read out by assistive technology when the
control gains focus.
Relying on the title
attribute for the visual display
of text content is currently discouraged as many user agents do not expose the attribute in an accessible manner
as required by this specification (e.g., requiring a pointing device such as a mouse to cause a tooltip to appear,
which excludes keyboard-only users and touch-only users, such as anyone with a modern phone or
tablet).
<label> Part number: <input pattern="[0-9][A-Z]{3}" name="part" title="A part number is a digit followed by three uppercase letters."/> </label>
...could cause the user agent to display an alert such as:
A part number is a digit followed by three uppercase letters.You cannot submit this form when the field is incorrect.
When a control has a pattern
attribute, the title
attribute, if used, must describe the pattern. Additional
information could also be included, so long as it assists the user in filling in the control.
Otherwise, assistive technology would be impaired.
For instance, if the title attribute contained the caption of the control, assistive technology could end up saying something like The text you have entered does not match the required pattern. Birthday, which is not useful.
user agents may still show the title
in non-error situations (for
example, as a tooltip when hovering over the control), so authors should be careful not to word title
s as if an error has necessarily occurred.
4.10.5.3.7. The min
and max
attributes
Some form controls can have explicit constraints applied limiting the allowed range of values that the user can provide. Normally, such a range would be linear and continuous. A form control can have a periodic domain, however, in which case the form control’s broadest possible range is finite, and authors can specify explicit ranges within it that span the boundaries.
Specifically, the broadest range of a type=time
control is midnight to midnight (24 hours), and
authors can set both continuous linear ranges (such as 9pm to 11pm) and discontinuous ranges
spanning midnight (such as 11pm to 1am).
The min
and max
attributes indicate the allowed range of values for
the element.
Their syntax is defined by the section that defines the type
attribute’s current state.
If the element has a min
attribute, and the result of
applying the algorithm to convert a string to a
number to the value of the min
attribute is a number,
then that number is the element’s minimum; otherwise, if the type
attribute’s current state defines a default minimum, then that is the minimum; otherwise, the element has no minimum.
The min
attribute also defines the step base.
If the element has a max
attribute, and the result of
applying the algorithm to convert a string to a
number to the value of the max
attribute is a number,
then that number is the element’s maximum; otherwise, if the type
attribute’s current state defines a default maximum, then that is the maximum; otherwise, the element has no maximum.
If the element does not have a periodic domain, the max
attribute’s value
(the maximum) must not be less than the min
attribute’s value
(its minimum).
If an element that does not have a periodic domain has a maximum that is less than its minimum, then so long as the element has a value, it will either be suffering from an underflow or suffering from an overflow.
An element has a reversed range if it has a periodic domain and its maximum is less than its minimum.
An element has range limitations if it has a defined minimum or a defined maximum.
How these range limitations apply depends on whether the element has a multiple
attribute.
- If the element does not have a
multiple
attribute specified or if themultiple
attribute does not apply -
Constraint validation: When the element has a minimum and does not have a reversed range, and the result of applying the algorithm to convert a string to a number to the string given by the element’s value is a number, and the number obtained from that algorithm is less than the minimum, the element is suffering from an underflow.
Constraint validation: When the element has a maximum and does not have a reversed range, and the result of applying the algorithm to convert a string to a number to the string given by the element’s value is a number, and the number obtained from that algorithm is more than the maximum, the element is suffering from an overflow.
Constraint validation: When an element has a reversed range, and the result of applying the algorithm to convert a string to a number to the string given by the element’s value is a number, and the number obtained from that algorithm is more than the maximum and less than the minimum, the element is simultaneously suffering from an underflow and suffering from an overflow.
- If the element does have a
multiple
attribute specified and themultiple
attribute does apply -
Constraint validation: When the element has a minimum, and the result of applying the algorithm to convert a string to a number to any of the strings in the element’s values is a number that is less than the minimum, the element is suffering from an underflow.
Constraint validation: When the element has a maximum, and the result of applying the algorithm to convert a string to a number to any of the strings in the element’s values is a number that is more than the maximum, the element is suffering from an overflow.
<input name=bday type=date max="1979-12-31">
<input name=quantity required="" type="number" min="1" value="1">
<input name="sleepStart" type=time min="21:00" max="06:00" step="60" value="00:00">
4.10.5.3.8. The step
attribute
The step
attribute indicates the granularity
that is expected (and required) of the value or values, by limiting the allowed values. The
section that defines the type
attribute’s current state also
defines the default step, the step scale factor, and in some cases the default step base, which are used in processing the
attribute as described below.
The step
attribute, if specified, must either have a
value that is a valid floating-point number that parses to a number that is greater than zero, or must have a
value that is an ASCII case-insensitive match for the string "any
".
The attribute provides the allowed value step for the element, as follows:
-
If the
step
attribute is absent, then the allowed value step is the default step multiplied by the step scale factor. -
Otherwise, if the attribute’s value is an ASCII case-insensitive match for the string "
any
", then there is no allowed value step. -
Otherwise, let step value be the result of running the rules for parsing floating-point number values, when they are applied to the
step
attribute’s value. -
If the previous step returned an error, or step value is zero, or a number less than zero, then the allowed value step is the default step multiplied by the step scale factor.
-
If the element’s
type
attribute is in the Date, Month, Week, or Time state, then round step value to the nearest whole number using the "round to nearest + round half up" technique, unless the value is less-than one, in which case let step value be 1. -
The allowed value step is step value multiplied by the step scale factor.
The step base is the value returned by the following algorithm:
-
If the element has a
min
content attribute, and the result of applying the algorithm to convert a string to a number to the value of themin
content attribute is not an error, then return that result and abort these steps. -
If the element has a
value
content attribute, and the result of applying the algorithm to convert a string to a number to the value of thevalue
content attribute is not an error, then return that result and abort these steps. -
If a default step base is defined for this element given its
type
attribute’s state, then return it and abort these steps. -
Return zero.
How these range limitations apply depends on whether the element has a multiple
attribute.
- If the element does not have a
multiple
attribute specified or if themultiple
attribute does not apply -
Constraint validation: When the element has an allowed value step, and the result of applying the algorithm to convert a string to a number to the string given by the value is a number, and that number is not step aligned, the element is suffering from a step mismatch.
- If the element does have a
multiple
attribute specified and themultiple
attribute does apply -
Constraint validation: When the element has an allowed value step, and the result of applying the algorithm to convert a string to a number to any of the strings in the values is a number that is not step aligned, the element is suffering from a step mismatch.
<input name=opacity type=range min=0 max=1 step=0.00392156863>
<input name=favtime type=time step=any>
Normally, time controls are limited to an accuracy of one minute.
4.10.5.3.9. The list
attribute
The list
attribute is used to identify an
element that lists predefined options suggested to the user.
If present, its value must be the ID of a datalist
element in the same document.
The suggestions source element is the first element in
the document in tree order to have an ID equal to the
value of the list
attribute, if that element is a datalist
element. If there is no list
attribute,
or if there is no element with that ID, or if the first element
with that ID is not a datalist
element, then there is
no suggestions source element.
If there is a suggestions source element, then, when
the user agent is allowing the user to edit the input
element’s value, the user agent should offer the suggestions represented by
the suggestions source element to the user in a manner
suitable for the type of control used. The user agent may use the suggestion’s label to identify the suggestion if appropriate.
User agents are encouraged to filter the suggestions represented by the suggestions source element when the number of suggestions is large, including only the most relevant ones (e.g., based on the user’s input so far). No precise threshold is defined, but capping the list at four to seven values is reasonable.
How user selections of suggestions are handled depends on whether the element is a control accepting a single value only, or whether it accepts multiple values:
- If the element does not have a
multiple
attribute specified or if themultiple
attribute does not apply -
When the user selects a suggestion, the
input
element’s value must be set to the selected suggestion’s value, as if the user had written that value themself. - If the element’s
type
attribute is in the Range state and the element has amultiple
attribute specified -
When the user selects a suggestion, the user agent must identify which value in the element’s values the user intended to update, and must then update the element’s values so that the relevant value is changed to the value given by the selected suggestion’s value, as if the user had themself set it to that value.
- If the element’s
type
attribute is in the E-mail state and the element has amultiple
attribute specified -
When the user selects a suggestion, the user agent must either add a new entry to the
input
element’s values, whose value is the selected suggestion’s value, or change an existing entry in theinput
element’s values to have the value given by the selected suggestion’s value, as if the user had themself added an entry with that value, or edited an existing entry to be that value. Which behavior is to be applied depends on the user interface in a user-agent-defined manner.
If the list
attribute does not
apply, there is no suggestions source element.
<label>Homepage: <input name=hp type=url list=hpurls></label> <datalist id=hpurls> <option value="https://www.google.com/" label="Google"> <option value="https://www.reddit.com/" label="Reddit"> </datalist>
Other URLs from the user’s history might show also; this is up to the user agent.
If the autocompletion list is merely an aid, and is not important to the content, then simply
using a datalist
element with children option
elements is enough. To
prevent the values from being rendered in legacy user agents, they need to be placed inside the value
attribute instead of inline.
<p> <label> Enter a breed: <input type="text" name="breed" list="breeds"> <datalist id="breeds"> <option value="Abyssinian"> <option value="Alpaca"> <!-- ... --> </datalist> </label> </p>
However, if the values need to be shown in legacy user agents, then fallback content can be placed
inside the datalist
element, as follows:
<p> <label> Enter a breed: <input type="text" name="breed" list="breeds"> </label> <datalist id="breeds"> <label> or select one from the list: <select name="breed"> <option value=""> (none selected) <option>Abyssinian <option>Alpaca <!-- ... --> </select> </label> </datalist> </p>
The fallback content will only be shown in user agents that don’t support datalist
. The
options, on the other hand, will be detected by all user agents, even though they are not children of the datalist
element.
Note that if an option
element used in a datalist
is selected
, it will be selected by default by legacy user agents
(because it affects the select
), but it will not have any effect on the input
element in user agents that support datalist
.
4.10.5.3.10. The placeholder
attribute
The placeholder
attribute represents a short hint (a word or short phrase) intended to aid the user with data entry when the
control has no value. A hint could be a sample value or a brief description of the expected
format. The attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or
U+000D CARRIAGE RETURN (CR) characters.
The placeholder
attribute should not be used as a
replacement for a label
. For a longer hint or other advisory text, place the text
next to the control.
Use of the placeholder
attribute as a replacement for a label
can reduce the
accessibility and usability of the control for a range of users including older
users and users with cognitive, mobility, fine motor skill or vision impairments.
While the hint given by the control’s label
is shown at all times, the short
hint given in the placeholder
attribute is only shown before the user enters a value. Furthermore, placeholder
text may be mistaken for
a pre-filled value, and as commonly implemented the default color of the placeholder text
provides insufficient contrast and the lack of a separate visible label
reduces the size of the hit region available for setting focus on the control.
User agents should present this hint to the user, after having stripped line breaks from it, when the element’s value is the empty string, especially if the control is not focused.
If a user agent normally doesn’t show this hint to the user when the control is focused, then the user agent should nonetheless show the hint for the control if it
was focused as a result of the autofocus
attribute, since
in that case the user will not have had an opportunity to examine the control before focusing
it.
placeholder
attribute:
<fieldset> <legend>Mail Account</legend> <p><label>Name: <input type="text" name="fullname" placeholder="John Ratzenberger"></label></p> <p><label>Address: <input type="email" name="address" placeholder="john@example.net"></label></p> <p><label>Password: <input type="password" name="password"></label></p> <p><label>Description: <input type="text" name="desc" placeholder="My Email Account"></label></p> </fieldset>
<input name=t1 type=tel placeholder="‫ رقم الهاتف 1 ‮"> <input name=t2 type=tel placeholder="‫ رقم الهاتف 2 ‮">
For slightly more clarity, here’s the same example using numeric character references instead of inline Arabic:
<input name=t1 type=tel placeholder="‫رقم الهاتف 1‮"> <input name=t2 type=tel placeholder="‫رقم الهاتف 2‮">
4.10.5.4. Common input
element APIs
- input .
value
[ = value ] -
Returns the current value of the form control.
Can be set, to change the value.
Throws an "
InvalidStateError
"DOMException
if it is set to any value other than the empty string when the control is a file upload control. - input .
checked
[ = value ] -
Returns the current checkedness of the form control.
Can be set, to change the checkedness.
- input .
files
-
Returns a
FileList
object listing the selected files of the form control.Returns null if the control isn’t a file control.
- input .
valueAsDate
[ = value ] -
Returns a
Date
object representing the form control’s value, if applicable; otherwise, returns null.Can be set, to change the value.
Throws an "
InvalidStateError
"DOMException
if the control isn’t date- or time-based. - input .
valueAsNumber
[ = value ] -
Returns a number representing the form control’s value, if applicable;
otherwise, returns NaN.
Can be set, to change the value. Setting this to NaN will set the underlying value to the empty string.
Throws an "
InvalidStateError
"DOMException
if the control is neither date- or time-based nor numeric. - input .
stepUp
( [ n ] )- input .
stepDown
( [ n ] ) - input .
-
Changes the form control’s value by the value given in the
step
attribute, multiplied by n. The default value for n is 1.Throws "
InvalidStateError
"DOMException
if the control is neither date- or time-based nor numeric, or if thestep
attribute’s value is "any
". - input .
list
- Returns the
datalist
element indicated by thelist
attribute.
The value
IDL attribute allows scripts to
manipulate the value of an input
element. The
attribute is in one of the following modes, which define its behavior:
-
value
-
On getting, it must return the current value of the element. On setting, it must set the element’s value to the new value, set the element’s dirty value flag to true, invoke the value sanitization algorithm, if the element’s
type
attribute’s current state defines one, and then, if the element has a text entry cursor position, should move the text entry cursor position to the end of the text field, unselecting any selected text and resetting the selection direction to none. -
default
-
On getting, if the element has a
value
attribute, it must return that attribute’s value; otherwise, it must return the empty string. On setting, it must set the element’svalue
attribute to the new value. -
default/on
-
On getting, if the element has a
value
attribute, it must return that attribute’s value; otherwise, it must return the string "on
". On setting, it must set the element’svalue
attribute to the new value. -
filename
-
On getting, it must return the string "
C:\fakepath\
" followed by the name of the first file in the list of selected files, if any, or the empty string if the list is empty. On setting, if the new value is the empty string, it must empty the list of selected files; otherwise, it must throw an "InvalidStateError
"DOMException
.This "fakepath" requirement is a sad accident of history. See the example in the File Upload state section for more information.
Since path components are not permitted in file names in the list of selected files, the "
\fakepath\
" cannot be mistaken for a path component.
The checked
IDL attribute allows scripts to
manipulate the checkedness of an input
element. On getting, it must return the current checkedness of the element; and on setting, it must set the
element’s checkedness to the new value and set the
element’s dirty checkedness flag to
true.
The files
IDL attribute allows scripts to
access the element’s selected files. On
getting, if the IDL attribute applies, it must return a FileList
object that represents the current selected files. The same object must be returned
until the list of selected files changes. If
the IDL attribute does not apply, then it must instead return
null. [FILEAPI]
The valueAsDate
IDL attribute represents
the value of the element, interpreted as a date.
On getting, if the valueAsDate
attribute does not apply, as defined for the input
element’s type
attribute’s current state, then return null. Otherwise, run
the algorithm to convert a string to a Date
object defined for that state to the element’s value; if the algorithm returned a Date
object, then
return it, otherwise, return null.
On setting, if the valueAsDate
attribute does not apply, as defined for the input
element’s type
attribute’s current state, then throw an InvalidStateError
exception; otherwise, if the new value is not null and not a Date
object throw a TypeError
exception; otherwise if the new value is null or a Date
object representing the NaN time value, then set the value of the element to the empty string; otherwise, run the algorithm to convert a Date
object to
a string, as defined for that state, on the new value, and set the value of the element to the resulting string.
The valueAsNumber
IDL attribute
represents the value of the element, interpreted as a
number.
On getting, if the valueAsNumber
attribute does not apply, as defined for the input
element’s type
attribute’s current state, then return a Not-a-Number (NaN)
value. Otherwise, if the valueAsDate
attribute applies, run the algorithm to convert a string to a Date
object defined for that state to the element’s value; if the algorithm returned a Date
object, then
return the time value of the object (the number of milliseconds from midnight UTC the
morning of 1970-01-01 to the time represented by the Date
object), otherwise, return
a Not-a-Number (NaN) value. Otherwise, run the algorithm to convert a string to a number defined for that state to the element’s value; if the
algorithm returned a number, then return it, otherwise, return a Not-a-Number (NaN) value.
On setting, if the new value is infinite, then throw a TypeError
exception.
Otherwise, if the valueAsNumber
attribute does not apply, as defined for the input
element’s type
attribute’s current state, then throw an InvalidStateError
exception. Otherwise, if the new value is a Not-a-Number (NaN)
value, then set the value of the element to the empty
string. Otherwise, if the valueAsDate
attribute applies, run the algorithm to convert a Date
object to a
string defined for that state, passing it a Date
object whose time
value is the new value, and set the value of the
element to the resulting string. Otherwise, run the algorithm to convert a number to a string, as
defined for that state, on the new value, and set the value of the element to the resulting string.
The stepDown(n)
and stepUp(n)
methods, when invoked, must run the following algorithm:
-
If the
stepDown()
andstepUp()
methods do not apply, as defined for theinput
element’stype
attribute’s current state, then throw an "InvalidStateError
"DOMException
, and abort these steps. -
If the element has no allowed value step, then throw an "
InvalidStateError
"DOMException
, and abort these steps. -
If the element has a minimum and a maximum and the minimum is greater than the maximum, then abort these steps.
-
If the element has a minimum and a maximum and there is no step aligned value greater than or equal to the element’s minimum and less than or equal to the element’s maximum, then abort these steps.
-
If applying the algorithm to convert a string to a number to the string given by the element’s value does not result in an error, then let value be the result of that algorithm. Otherwise, let value be zero.
-
Let valueBeforeStepping be value.
-
If value is not step aligned, then:
-
If the method invoked was the
stepDown()
method, then step-align value with negative preference. Otherwise step-align value with positive preference. In either case, let value be the result.This ensures that the value first snaps to a step-aligned value when it doesn’t start step-aligned. For example, starting with the followinginput
withvalue
of 3:<input type="number" value="3" min="1" max="10" step="2.6">
Invoking the
stepUp()
method will snap thevalue
to 3.6; subsequent invocations will increment the value by 2.6 (e.g., 6.2, then 8.8). Likewise, the followinginput
element in the Week state will also step-align in similar fashion, though in this state, thestep
value is rounded to 3, per the derivation of the allowed value step.<input type="week" value="2016-W20" min="2016-W01" max="2017-W01" step="2.6">
Invoking
stepUp()
will result in avalue
of "2016-W22
" because the nearest step-aligned value from the step base of "2016-W01
" (themin
value) with 3 weekstep
s that is greater than thevalue
of "2016-W20
" is "2016-W22
" (i.e.: W01, W04, W07, W10, W13, W16, W19, W22).
Otherwise (value is step aligned), run the following substeps:
-
Let n be the argument.
-
Let delta be the allowed value step multiplied by n.
-
If the method invoked was the
stepDown()
method, negate delta. -
Let value be the result of adding delta to value.
-
-
If the element has a minimum, and value is less than that minimum, then set value to the step-aligned minimum value with positive preference.
-
If the element has a maximum, and value is greater than that maximum, then set value to the step-aligned maximum value with negative preference.
-
If either the method invoked was the
stepDown()
method and value is greater than valueBeforeStepping, or the method invoked was thestepUp()
method and value is less than valueBeforeStepping, then abort these steps. -
Let value as string be the result of running the algorithm to convert a number to a string, as defined for the
input
element’stype
attribute’s current state, on value. -
Set the value of the element to value as string.
To determine if a value v is step aligned do the following:
This algorithm checks to see if a value falls along an input
element’s
defined step
intervals, with the interval’s origin at the step base value. It is
used to determine if the element’s value is suffering from a step mismatch and for various checks in the stepUp()
and stepDown()
methods.
-
Subtract the step base from v and let the result be relative distance.
-
If dividing the relative distance by the allowed value step results in a value with a remainder then v is not step aligned. Otherwise it is step aligned.
To step-align a value v with either negative preference or positive preference, do the following:
negative preference selects a step-aligned value that is less than or equal to v, while positive preference step-aligns with a value greater than or equal to v.
-
Subtract the step base from v and let the result be relative distance.
-
Let step interval count be the result of integer dividing (or divide and throw out any remainder) relative distance by the allowed value step.
-
Let candidate be the step interval count multiplied by the allowed value step.
-
If this algorithm was invoked with negative preference and the value of v is less than candidate, then decrement candidate by the allowed value step.
Otherwise, if this algorithm was invoked with positive preference and the value of v is greater than candidate, then increment candidate by the allowed value step.
-
The step-aligned value is candidate. Return candidate.
The list
IDL attribute must return the
current suggestions source element, if any, or null otherwise.
4.10.5.5. Common event behaviors
When the input
and change
events apply (which is the case for all input
controls other than buttons and those with the type
attribute in the state), the events are fired to indicate that the
user has interacted with the control. The input
event fires whenever the user has modified the data of the control. The change
event fires when the value is committed, if
that makes sense for the control, or else when the control loses focus. In all cases, the input
event comes before the corresponding change
event (if any).
When an input
element has a defined activation behavior, the rules
for dispatching these events, if they apply, are given
in the section above that defines the type
attribute’s
state. (This is the case for all input
controls with the type
attribute in the Checkbox state, the Radio Button state, or the File Upload state.)
For input
elements without a defined activation behavior, but to
which these events apply, and for which the user
interface involves both interactive manipulation and an explicit commit action, then when the user
changes the element’s value, the user agent must queue a task to fire a simple event that bubbles named input
at the input
element, and any time the user
commits the change, the user agent must queue a task to fire a simple
event that bubbles named change
at the input
element.
An example of a user interface involving both interactive manipulation and a
commit action would be a Range controls that use a
slider, when manipulated using a pointing device. While the user is dragging the control’s knob, input
events would fire whenever the position changed,
whereas the change
event would only fire when the user
let go of the knob, committing to a specific value.
For input
elements without a defined activation behavior, but to
which these events apply, and for which the user
interface involves an explicit commit action but no intermediate manipulation, then any time the
user commits a change to the element’s value, the user
agent must queue a task to first fire a simple event that bubbles named input
at the input
element, and then fire a simple event that bubbles named change
at the input
element.
An example of a user interface with a commit action would be a Color control that consists of a single button that brings up a color wheel: if the value only changes when the dialog is closed, then that would be the explicit commit action. On the other hand, if manipulating the control changes the color interactively, then there might be no commit action.
Another example of a user interface with a commit action would be a Date control that allows both text-based user input and user selection from a drop-down calendar: while text input does not have an explicit commit step, selecting a date from the drop down calendar and then dismissing the drop down would be a commit action.
The Range control is also an example of a
user interface that has a commit action when used with a pointing device (rather than a keyboard):
during the time that the pointing device starts manipulating the slider until the time that the
slider is released, no commit action is taken (though input
events are fired as the
value is changed). Only after the slider is release is the commit action taken.
For input
elements without a defined activation behavior, but to
which these events apply, any time the user causes the
element’s value to change without an explicit commit
action, the user agent must queue a task to fire a simple event that
bubbles named input
at the input
element. The
corresponding change
event, if any, will be fired when
the control loses focus.
Examples of a user changing the element’s value would include the user typing into a text field, pasting a new value into the field, or undoing an edit in that field. Some user interactions do not cause changes to the value, e.g., hitting the "delete" key in an empty text field, or replacing some text in the field with text from the clipboard that happens to be exactly the same text.
A Range control in the form of a slider that the user has focused and is interacting with using a keyboard would be another example of the user changing the element’s value without a commit step.
In the case of tasks that just fire an input
event, user agents may wait for a suitable break in the
user’s interaction before queuing the tasks; for example, a
user agent could wait for the user to have not hit a key for 100ms, so as to only fire the event
when the user pauses, instead of continuously for each keystroke.
When the user agent is to change an input
element’s value on behalf of the user (e.g., as part of a form prefilling
feature), the user agent must queue a task to first update the value accordingly, then fire a simple event that
bubbles named input
at the input
element,
then fire a simple event that bubbles named change
at the input
element.
These events are not fired in response to changes made to the values of form controls by scripts. (This is to make it easier to update the values of form controls in response to the user manipulating the controls, without having to then filter out the script’s own changes to avoid an infinite loop.)
The task source for these tasks is the user interaction task source.
4.10.6. The button
element
- Categories:
- Flow content.
- Phrasing content.
- Interactive content.
- listed, labelable, submittable, and reassociateable form-associated element.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content, but there must be no interactive content descendant.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
autofocus
- Automatically focus the form control when the page is loadeddisabled
- Whether the form control is disabledform
- Associates the control with aform
elementformaction
- URL to use for §4.10.22 Form submissionformenctype
- Form data set encoding type to use for §4.10.22 Form submissionformmethod
- HTTP method to use for §4.10.22 Form submissionformnovalidate
- Bypass form control validation for §4.10.22 Form submissionformtarget
- browsing context for §4.10.22 Form submissionmenu
- Specifies the element’s designated pop-up menuname
- Name of form control to use for §4.10.22 Form submission and in theform.elements
APItype
- Type of buttonvalue
- Value to be used for §4.10.22 Form submission - Allowed ARIA role attribute values:
button
(default - do not set),link
,menuitem
,menuitemcheckbox
,menuitemradio
orradio
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLButtonElement : HTMLElement { attribute boolean autofocus; attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute DOMString formAction; attribute DOMString formEnctype; attribute DOMString formMethod; attribute boolean formNoValidate; attribute DOMString formTarget; attribute DOMString name; attribute DOMString type; attribute DOMString value; attribute HTMLMenuElement? menu; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; };
The button
element represents a button labeled by its contents.
The element is a button.
The type
attribute controls the behavior of
the button when it is activated. It is an enumerated attribute. The following table
lists the keywords and states for the attribute — the keywords in the left column map to the
states in the cell in the second column on the same row as the keyword.
Keyword | State | Brief description |
---|---|---|
submit
| submit button | Submits the form. |
reset
| reset button | Resets the form. |
button
| Button | Does nothing. |
menu
| Menu | Shows a menu. |
The missing value default is the submit button state.
If the type
attribute is in the submit button state, the element is specifically a submit button.
Constraint validation: If the type
attribute is in the reset button state, the Button state, or the Menu state, the element is barred from constrain validation.
When a button
element is not disabled,
its activation behavior element is to run the steps defined in the following list for
the current state of the element’s type
attribute:
- submit button
- If the element has a form owner and the element’s node document is fully active, the element must submit the form owner from the
button
element. - reset button
- If the element has a form owner and the element’s node document is fully active, the element must reset the form owner.
- Button
- Do nothing.
- Menu
-
The element must follow these steps:
- If the
button
is not being rendered, abort these steps. - If the
button
element’s node document is not fully active, abort these steps. - Let menu be the element’s designated pop-up menu, if any. If there isn’t one, then abort these steps.
- Fire a trusted event with the name
show
at menu, using theRelatedEvent
interface, with therelatedTarget
attribute initialized to thebutton
element. The event must be cancelable. - If the event is not canceled, then build and
show the menu for menu, with the
button
element as the subject.
- If the
The form
attribute is used to explicitly associate the button
element with its form owner. The name
attribute represents the element’s name. The disabled
attribute is used to make the control non-interactive and
to prevent its value from being submitted. The autofocus
attribute controls focus. The formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
attributes are attributes for form
submission.
The formnovalidate
attribute can be
used to make submit buttons that do not trigger the constraint validation.
The formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
must not be specified if the element’s type
attribute is not in the submit button state.
The value
attribute gives the element’s value
for the purposes of form submission. The element’s value is
the value of the element’s value
attribute, if there is
one, or the empty string otherwise.
A button (and its value) is only included in the form submission if the button itself was used to initiate the form submission.
If the element’s type
attribute is in the Menu state, the menu
attribute must be specified to give the element’s
menu. The value must be the ID of a menu
element in
the same home subtree whose type
attribute is in
the popup menu state. The attribute must not be specified if
the element’s type
attribute is not in the Menu state.
A button
element’s designated pop-up menu is the first element in the button
's home subtree whose ID is that given by the button
element’s menu
attribute, if there is such an element and
its type
attribute is in the popup menu state; otherwise, the element has no designated pop-up
menu.
The value
and menu
IDL attributes must reflect the content attributes of the same name.
The type
IDL attribute must reflect the content attribute of the same name, limited to only known values.
The willValidate
, validity
, and validationMessage
IDL attributes, and
the checkValidity()
, reportValidity()
, and setCustomValidity()
methods, are part of
the constraint validation API.
The labels
IDL attribute provides a list of the element’s label
s.
The autofocus
, disabled
, form
, and name
IDL attributes are
part of the element’s forms API.
<button type=button onclick="alert('This 15-20 minute piece was composed by George Gershwin.')"> Show hint </button>
4.10.7. The select
element
- Categories:
- Flow content.
- Phrasing content.
- Interactive content.
- listed, labelable, submittable, resettable, and reassociateable form-associated element.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Zero or more
option
,optgroup
, and script-supporting elements. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
autofocus
- Automatically focus the form control when the page is loadeddisabled
- Whether the form control is disabledform
- Associates the control with aform
elementmultiple
- Whether to allow multiple valuesname
- Name of form control to use for §4.10.22 Form submission and in theform.elements
APIrequired
- Whether the control is required for §4.10.22 Form submissionsize
- Size of the control - Allowed ARIA role attribute values:
listbox
(default - do not set) ormenu
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLSelectElement : HTMLElement { attribute DOMString autocomplete; attribute boolean autofocus; attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute boolean multiple; attribute DOMString name; attribute boolean required; attribute unsigned long size; readonly attribute DOMString type; [SameObject] readonly attribute HTMLOptionsCollection options; attribute unsigned long length; getter Element? item(unsigned long index); HTMLOptionElement? namedItem(DOMString name); void add((HTMLOptionElement or HTMLOptGroupElement) element, optional (HTMLElement or long)? before = null); void remove(); // ChildNode overload void remove(long index); setter void (unsigned long index, HTMLOptionElement? option); [SameObject] readonly attribute HTMLCollection selectedOptions; attribute long selectedIndex; attribute DOMString value; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; };
The select
element represents a control for selecting amongst a set of
options.
The multiple
attribute is a boolean
attribute. If the attribute is present, then the select
element represents a control for selecting zero or more options from the list of options. If the attribute is absent, then the select
element represents a control for selecting a single option from
the list of options.
The size
attribute gives the number of options
to show to the user. The size
attribute, if specified, must
have a value that is a valid non-negative integer greater than zero.
The display size of a select
element is the
result of applying the rules for parsing non-negative integers to the value of
element’s size
attribute, if it has one and parsing it is
successful. If applying those rules to the attribute’s value is not successful, or if the size
attribute is absent, then the element’s display size is 4 if the element’s multiple
content attribute is present, and 1 otherwise.
The list of options for a select
element consists of all the option
element children of the select
element, and all the option
element children of all the optgroup
element
children of the select
element, in tree order.
The required
attribute is a boolean
attribute. When specified, the user will be required to select a value before submitting
the form.
If a select
element has a required
attribute specified, does not have a multiple
attribute
specified, and has a display size of 1; and if the value of the first option
element in the select
element’s list of options (if
any) is the empty string, and that option
element’s parent node is the select
element (and not an optgroup
element), then that option
is the select
element’s placeholder label option.
If a select
element has a required
attribute specified, does not have a multiple
attribute
specified, and has a display size of 1, then the select
element must have a placeholder label option.
In practice, the requirement stated in the paragraph above can only apply when a select
element does not have a sizes
attribute
with a value greater than 1.
Constraint validation: If the element has its required
attribute specified, and either none of the option
elements in the select
element’s list of options have their selectedness set to true, or the only option
element in the select
element’s list of options with its selectedness set to true is the placeholder label
option, then the element is suffering from being missing.
If the multiple
attribute is absent, and the element
is not disabled, then the user agent should allow the
user to pick an option
element in its list
of options that is itself not disabled. Upon
this option
element being picked (either
through a click, or through unfocusing the element after changing its value, or through a menu command, or through any other mechanism), and before the
relevant user interaction event is queued (e.g., before the click
event), the user agent must set the selectedness of the picked option
element
to true, set its dirtiness to true, and then send select
update notifications.
If the multiple
attribute is absent, whenever an option
element in the select
element’s list of options has its selectedness set to true, and whenever an option
element with its selectedness set to true is added to the select
element’s list of options,
the user agent must set the selectedness of all
the other option
elements in its list of
options to false.
If the multiple
attribute is absent and the
element’s display size is greater than 1, then the user
agent should also allow the user to request that the option
whose selectedness is true, if any, be unselected. Upon this
request being conveyed to the user agent, and before the relevant user interaction event is queued (e.g., before the click
event), the user agent must set the selectedness of that option
element to
false, set its dirtiness to true, and then send select
update notifications.
If nodes are inserted or nodes are removed causing the list of options to gain or lose one or more option
elements, or if an option
element in the list of options asks for a reset, then, if the select
element’s multiple
attribute is absent, the user agent must run the
first applicable set of steps from the following list:
- If the
select
element’s display size is 1, and nooption
elements in theselect
element’s list of options have their selectedness set to true - Set the selectedness of the first
option
element in the list of options in tree order that is not disabled, if any, to true. - If two or more
option
elements in theselect
element’s list of options have their selectedness set to true - Set the selectedness of all but the last
option
element with its selectedness set to true in the list of options in tree order to false.
If the multiple
attribute is present, and the
element is not disabled, then the user agent should
allow the user to toggle the selectedness of the option
elements in
its list of options that are themselves not disabled. Upon such an element being toggled (either through a click, or through a menu command, or any other mechanism), and before the relevant user
interaction event is queued (e.g., before a related click
event), the selectedness of the option
element must
be changed (from true to false or false to true), the dirtiness of the element must be set to true, and the
user agent must send select
update notifications.
When the user agent is to send select
update notifications, queue
a task to first fire a simple event that bubbles named input
at the select
element, and then fire a simple
event that bubbles named change
at the select
element, using the user interaction task source as the task
source. If the JavaScript execution context stack was not empty when the user agent was
to send select
update notifications, then the resulting input
and change
events must not be trusted.
The reset algorithm for select
elements is to go through all the option
elements in the element’s list of options, set their selectedness to true if the option
element has a selected
attribute, and false otherwise,
set their dirtiness to false, and then have the option
elements ask for a reset.
The form
attribute is used to explicitly associate the select
element with its form owner.
The name
attribute represents the element’s name.
The disabled
attribute is used to make the control non-interactive and to prevent its value from being submitted.
The autofocus
attribute controls focus.
The autocomplete
attribute controls how the user agent provides autofill behavior.
A select
element that is not disabled is mutable.
- select .
type
-
Returns "
select-multiple
" if the element has amultiple
attribute, and "select-one
" otherwise. - select .
options
-
Returns an
HTMLOptionsCollection
of the list of options. - select .
length
[ = value ] -
Returns the number of elements in the list of options.
When set to a smaller number, truncates the number of
option
elements in theselect
.When set to a greater number, adds new blank
option
elements to theselect
. - element = select .
item
(index)- select[index]
-
Returns the item with index index from the list of options. The items are sorted in tree order.
- element = select .
namedItem
(name) -
Returns the first item with ID or
name
name from the list of options.Returns null if no element with that ID could be found.
- select .
add
(element [, before ] ) -
Inserts element before the node given by before.
The before argument can be a number, in which case element is inserted before the item with that number, or an element from the list of options, in which case element is inserted before that element.
If before is omitted, null, or a number out of range, then element will be added at the end of the list.
This method will throw a
HierarchyRequestError
exception if element is an ancestor of the element into which it is to be inserted. - select .
selectedOptions
-
Returns an
HTMLCollection
of the list of options that are selected. - select .
selectedIndex
[ = value ] -
Returns the index of the first selected item, if any, or -1 if there is no selected item.
Can be set, to change the selection.
- select .
value
[ = value ] -
Returns the value of the first selected item, if any, or the empty string if there is no selected item.
Can be set, to change the selection.
The type
IDL attribute, on getting, must
return the string "select-one
" if the multiple
attribute is absent, and the string "select-multiple
" if the multiple
attribute is present.
The options
IDL attribute must return an HTMLOptionsCollection
rooted at the select
node, whose filter matches
the elements in the list of options.
The options
collection is also mirrored on the HTMLSelectElement
object. The supported property indices at any instant
are the indices supported by the object returned by the options
attribute at that instant.
The length
IDL attribute must return the
number of nodes represented by the options
collection. On setting, it must act like the attribute
of the same name on the options
collection.
The item(index)
method
must return the value returned by the method of the same
name on the options
collection, when invoked with
the same argument.
The namedItem(name)
method must return the value returned by the
method of the same name on the options
collection,
when invoked with the same argument.
When the user agent is to set the value of a new
indexed property for a given property index index to a new value value, it must instead set the
value of a new indexed property with the given property index index to
the new value value on the options
collection.
Similarly, the add()
method must act like its
namesake method on that same options
collection.
The remove()
method must act like its
namesake method on that same options
collection when it
has arguments, and like its namesake method on the ChildNode
interface implemented by
the HTMLSelectElement
ancestor interface Element
when it has no
arguments.
The selectedOptions
IDL attribute
must return an HTMLCollection
rooted at the select
node, whose filter
matches the elements in the list of options that
have their selectedness set to true.
The selectedIndex
IDL attribute, on
getting, must return the index of the first option
element in the list of
options in tree order that has its selectedness set to true, if any. If there isn’t one,
then it must return -1.
On setting, the selectedIndex
attribute must set
the selectedness of all the option
elements in the list of options to false, and
then the option
element in the list of
options whose index is the given new value, if
any, must have its selectedness set to true and
its dirtiness set to true.
This can result in no element having a selectedness set to true even in the case of the select
element having no multiple
attribute and a display size of 1.
The value
IDL attribute, on getting, must
return the value of the first option
element in the list of options in tree
order that has its selectedness set to
true, if any. If there isn’t one, then it must return the empty string.
On setting, the value
attribute must set the selectedness of all the option
elements
in the list of options to false, and then the
first option
element in the list of
options, in tree order, whose value is equal to the given new value, if any, must have its selectedness set to true and its dirtiness set to true.
This can result in no element having a selectedness set to true even in the case of the select
element having no multiple
attribute and a display size of 1.
The multiple
, required
, and size
IDL attributes must reflect the
respective content attributes of the same name. The size
IDL
attribute has a default value of zero.
For historical reasons, the default value of the size
IDL attribute does not return the actual size used, which, in
the absence of the size
content attribute, is either 1 or 4
depending on the presence of the multiple
attribute.
The willValidate
, validity
, and validationMessage
IDL attributes, and
the checkValidity()
, reportValidity()
, and setCustomValidity()
methods, are part of
the constraint validation API.
The labels
IDL attribute provides a list of the element’s label
s.
The autofocus
, disabled
, form
, and name
IDL attributes are part of the
element’s forms API.
select
element can be used to offer the user
with a set of options from which the user can select a single option. The default option is
preselected.
<p> <label for="unittype">Select unit type:</label> <select id="unittype" name="unittype"> <option value="1"> Miner </option> <option value="2"> Puffer </option> <option value="3" selected> Snipey </option> <option value="4"> Max </option> <option value="5"> Firebot </option> </select> </p>
When there is no default option, a value that provides instructions or a hint (placeholder option) can be used instead:
<select name="unittype" required> <option value=""> Select unit type </option> <option value="1"> Miner </option> <option value="2"> Puffer </option> <option value="3"> Snipey </option> <option value="4"> Max </option> <option value="5"> Firebot </option> </select>
<p> <label for="allowedunits">Select unit types to enable on this map:</label> <select id="allowedunits" name="allowedunits" multiple> <option value="1" selected> Miner </option> <option value="2" selected> Puffer </option> <option value="3" selected> Snipey </option> <option value="4" selected> Max </option> <option value="5" selected> Firebot </option> </select> </p>
<p>Select the songs from that you would like on your Act II Mix Tape:</p> <select multiple required name="act2"> <option value="s1">It Sucks to Be Me (Reprize) <option value="s2">There is Life Outside Your Apartment <option value="s3">The More You Ruv Someone <option value="s4">Schadenfreude <option value="s5">I Wish I Could Go Back to College <option value="s6">The Money Song <option value="s7">School for Monsters <option value="s8">The Money Song (Reprize) <option value="s9">There’s a Fine, Fine Line (Reprize) <option value="s10">What Do You Do With a B.A. in English? (Reprize) <option value="s11">For Now </select>
4.10.8. The datalist
element
- Categories:
- Flow content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Either: phrasing content.
- Or: Zero or more
option
and script-supporting elements. - Or: Zero or more
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
listbox
(default - do not set).- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLDataListElement : HTMLElement { [SameObject] readonly attribute HTMLCollection options; };
The datalist
element represents a set of option
elements that
represent predefined options for other controls. In the rendering, the datalist
element represents nothing and it, along with its children, should
be hidden.
The datalist
element can be used in two ways. In the simplest case, the datalist
element has just option
element children.
<label> Sex: <input name=sex list=sexes> <datalist id=sexes> <option value="Female"> <option value="Male"> </datalist> </label>
In the more elaborate case, the datalist
element can be given contents that are to
be displayed for down-level clients that don’t support datalist
. In this case, the option
elements are provided inside a select
element inside the datalist
element.
<label> Sex: <input name=sex list=sexes> </label> <datalist id=sexes> <label> or select from the list: <select name=sex> <option value=""> <option>Female <option>Male </select> </label> </datalist>
The datalist
element is hooked up to an input
element using the list
attribute on the input
element.
Each option
element that is a descendant of the datalist
element,
that is not disabled, and whose value is a string that isn’t the empty string, represents a
suggestion. Each suggestion has a value and a label.
- datalist .
options
- Returns an
HTMLCollection
of theoption
elements of thedatalist
element.
The options
IDL attribute must return an HTMLCollection
rooted at the datalist
node, whose filter matches option
elements.
Constraint validation: If an element has a datalist
element
ancestor, it is barred from constraint validation.
4.10.9. The optgroup
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
select
element. - Content model:
- Zero or more
option
and script-supporting elements. - Tag omission in text/html:
- An
optgroup
element’s end tag may be omitted if theoptgroup
element is immediately followed by anotheroptgroup
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
disabled
- Whether the form control is disabledlabel
- User-visible label - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLOptGroupElement : HTMLElement { attribute boolean disabled; attribute DOMString label; };
The optgroup
element represents a group of option
elements with a common label.
The element’s group of option
elements consists of the option
elements that are children of the optgroup
element.
When showing option
elements in select
elements, user agents should
show the option
elements of such groups as being related to each other and separate
from other option
elements.
The disabled
content attribute is a boolean attribute and can be used to disable a group of option
elements
together.
The label
content attribute must be specified. Its
value gives the name of the group, for the purposes of the user interface. User
agents should use this attribute’s value when labeling the group of option
elements
in a select
element.
The disabled
and label
IDL attributes must reflect the
respective content attributes of the same name.
There is no way to select an optgroup
element. Only option
elements can be selected. An optgroup
element merely provides a
label for a group of option
elements.
select
drop-down widget:
<form action="courseselector.dll" method="get"> <p>Which course would you like to watch today? <p><label>Course: <select name="c"> <optgroup label="8.01 Physics I: Classical Mechanics"> <option value="8.01.1">Lecture 01: Powers of Ten <option value="8.01.2">Lecture 02: 1D Kinematics <option value="8.01.3">Lecture 03: Vectors <optgroup label="8.02 Electricity and Magnestism"> <option value="8.02.1">Lecture 01: What holds our world together? <option value="8.02.2">Lecture 02: Electric Field <option value="8.02.3">Lecture 03: Electric Flux <optgroup label="8.03 Physics III: Vibrations and Waves"> <option value="8.03.1">Lecture 01: Periodic Phenomenon <option value="8.03.2">Lecture 02: Beats <option value="8.03.3">Lecture 03: Forced Oscillations with Damping </select> </label> <p><input type=submit value="▶ Play"> </form>
4.10.10. The option
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
select
element.- As a child of a
datalist
element.- As a child of an
optgroup
element. - As a child of a
- Content model:
- If the element has a
label
attribute and avalue
attribute: Nothing.- If the element has a
label
attribute but novalue
attribute: Text.- If the element has no
label
attribute: Text. - If the element has a
- Tag omission in text/html:
- An
option
element’s end tag may be omitted if theoption
element is immediately followed by anotheroption
element, or if it is immediately followed by anoptgroup
element, or if there is no more content in the parent element. - Content attributes:
- Global attributes
disabled
- Whether the form control is disabledlabel
- User-visible labelselected
- Whether the option is selected by defaultvalue
- Value to be used for §4.10.22 Form submission - Allowed ARIA role attribute values:
option
(default - do not set),menuitem
,menuitemradio
orseparator
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
[NamedConstructor=Option(optional DOMString text = "", optional DOMString value, optional boolean defaultSelected = false, optional boolean selected = false)] interface HTMLOptionElement : HTMLElement { attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute DOMString label; attribute boolean defaultSelected; attribute boolean selected; attribute DOMString value; attribute DOMString text; readonly attribute long index; };
The option
element represents an option in a select
element or as part of a list of
suggestions in a datalist
element.
In certain circumstances described in the definition of the select
element, an option
element can be a select
element’s placeholder label option. A placeholder label option does not represent an actual option, but instead represents a
label for the select
control.
The disabled
content attribute is a boolean attribute. An option
element is disabled if its disabled
attribute
is present or if it is a child of an optgroup
element whose disabled
attribute is
present.
An option
element that is disabled must prevent any click
events
that are queued on the user interaction task source from being dispatched on the
element.
The label
content attribute provides a label for
the element. The label of an option
element is the value of the label
content attribute, if there is one and its value is not the empty string, or, otherwise, the value
of the element’s text
IDL attribute if its value is not the empty string.
The label
content attribute, if specified, must not be empty.
The value
content attribute provides a value for
element. The value of an option
element is the value of the value
content
attribute, if there is one, or, if there is not, the value of the element’s text
IDL attribute (which may be the empty string).
The selected
content attribute is a boolean attribute. It represents the default selectedness of the
element.
The dirtiness of an option
element is a boolean state, initially
false. It controls whether adding or removing the selected
content attribute has any
effect.
The selectedness of an option
element is a boolean state,
initially false. Except where otherwise specified, when the element is created, its selectedness must be set to true if the element has a selected
attribute. Whenever an option
element’s selected
attribute is
added, if its dirtiness is false, its selectedness must be set to true. Whenever an option
element’s selected
attribute is removed, if its dirtiness is
false, its selectedness must be set to false.
The Option()
constructor,
when called with three or fewer arguments, overrides the initial state of the selectedness state to always be false even if the third argument is true
(implying that a selected
attribute is to be set). The fourth argument can be used to
explicitly set the initial selectedness state when using the
constructor.
A select
element whose multiple
attribute is not specified must not have more than
one descendant option
element with its selected
attribute set.
An option
element’s index is the number of option
elements that are
in the same list of options but that come before it in tree order. If the option
element is not in a list of options, then the option
element’s index
is zero.
- option .
selected
-
Returns true if the element is selected, and false otherwise.
Can be set, to override the current state of the element.
- option .
index
- Returns the index of the element in its
select
element’soptions
list. - option .
form
- Returns the element’s
form
element, if any, or null otherwise. - option .
text
- Same as
textContent
, except that spaces are collapsed andscript
elements are skipped. - option = new
Option()
( [ text [, value [, defaultSelected [, selected ] ] ] ] ) -
Returns a new
option
element.The text argument sets the contents of the element.
The value argument sets the
value
attribute.The defaultSelected argument sets the
selected
attribute.The selected argument sets whether or not the element is selected. If it is omitted, even if the defaultSelected argument is true, the element is not selected.
The disabled
IDL attribute must reflect the content attribute of the same name. The defaultSelected
IDL attribute must reflect the selected
content attribute.
The label
IDL attribute, on getting, if
there is a label
content attribute, must return that attribute’s value; otherwise, it
must return the element’s label. On setting, the element’s label
content
attribute must be set to the new value.
The value
IDL attribute, on getting,
must return the element’s value. On setting, the element’s value
content attribute must be set to the new value.
The selected
IDL attribute, on getting,
must return true if the element’s selectedness is true, and false
otherwise. On setting, it must set the element’s selectedness to the new
value, set its dirtiness to true, and then cause the element to ask for a reset.
The index
IDL attribute must return the
element’s index.
The text
IDL attribute, on getting, must
return the result of stripping and collapsing whitespace from the concatenation of data of all the Text
node descendants of the option
element, in tree order,
excluding any that are descendants of descendants of the option
element that are themselves script
elements in the HTML namespace or script
elements in the SVG namespace.
On setting, the text
attribute must act as if the textContent
IDL
attribute on the element had been set to the new value.
The form
IDL attribute’s behavior depends on whether the option
element
is in a select
element or not. If the option
has a select
element as its parent, or
has an optgroup
element as its parent and that optgroup
element has a select
element
as its parent, then the form
IDL attribute must return the same value as the form
IDL attribute on that select
element. Otherwise, it must return
null.
A constructor is provided for creating HTMLOptionElement
objects (in addition to the factory
methods from DOM such as createElement()
): Option(text, value, defaultSelected, selected)
.
When invoked as a constructor, it must return a new HTMLOptionElement
object (a new option
element). If the first argument is not the empty string, the new object must have as its only
child a Text
node whose data is the value of that argument. Otherwise, it must have no
children. If the value argument is present, the new object must have a value
attribute set with the value of the argument as its value. If the defaultSelected argument is true, the new object must have a selected
attribute set with no value. If the selected argument is true, the new object must have
its selectedness set to true; otherwise the selectedness must be set to false, even if the defaultSelected argument is true. The element’s node document must be the active document of the browsing context of the Window
object on which the
interface object of the invoked constructor is found.
4.10.11. The textarea
element
- Categories:
- Flow content.
- Phrasing content.
- Interactive content.
- listed, labelable, submittable, resettable, and reassociateable form-associated element.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Text.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
autocomplete
- Hint for form autofill featureautofocus
- Automatically focus the form control when the page is loadedcols
- Maximum number of characters per linedirname
- Name of form field to use for sending the element’s directionality in §4.10.22 Form submissiondisabled
- Whether the form control is disabledform
- Associates the control with aform
elementinputmode
- Hint for selecting an input modalitymaxlength
- Maximum length of valueminlength
- Minimum length of valuename
- Name of form control to use for §4.10.22 Form submission and in theform.elements
APIplaceholder
- User-visible label to be placed within the form controlreadonly
- Whether to allow the value to be edited by the userrequired
- Whether the control is required for §4.10.22 Form submissionrows
- Number of lines to showwrap
- How the value of the form control is to be wrapped for §4.10.22 Form submission - Allowed ARIA role attribute values:
textbox
(default - do not set).- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLTextAreaElement : HTMLElement { attribute DOMString autocomplete; attribute boolean autofocus; attribute unsigned long cols; attribute DOMString dirName; attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute DOMString inputMode; attribute long maxLength; attribute long minLength; attribute DOMString name; attribute DOMString placeholder; attribute boolean readOnly; attribute boolean required; attribute unsigned long rows; attribute DOMString wrap; readonly attribute DOMString type; attribute DOMString defaultValue; [TreatNullAs=EmptyString] attribute DOMString value; readonly attribute unsigned long textLength; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; void select(); attribute unsigned long selectionStart; attribute unsigned long selectionEnd; attribute DOMString selectionDirection; void setRangeText(DOMString replacement); void setRangeText(DOMString replacement, unsigned long start, unsigned long end, optional SelectionMode selectionMode = "preserve"); void setSelectionRange(unsigned long start, unsigned long end, optional DOMString direction); };
The textarea
element represents a multiline plain text edit
control for the element’s raw
value. The contents of the control represent the control’s default value.
The raw value of a textarea
control must be initially the empty string.
This element has rendering requirements involving the bidirectional algorithm.
The readonly
attribute is a boolean attribute used to control whether the text can be edited by the user or
not.
Filename: <code>/etc/bash.bashrc</code> <textarea name="buffer" readonly> # System-wide .bashrc file for interactive bash(1) shells. # To enable the settings / commands in this file for login shells as well, # this file has to be sourced in /etc/profile. # If not running interactively, don’t do anything [ -z "$PS1" ] && return ...</textarea>
Constraint validation: If the readonly
attribute is specified on a textarea
element, the element is barred from constraint validation.
A textarea
element is mutable if it is
neither disabled nor has a readonly
attribute specified.
When a textarea
is mutable, its raw value should be editable by the user: the user agent
should allow the user to edit, insert, and remove text, and to insert and remove line breaks in
the form of U+000A LINE FEED (LF) characters. Any time the user causes the element’s raw value to change, the user agent must queue a
task to fire a simple event that bubbles named input
at the textarea
element. User agents may wait for a
suitable break in the user’s interaction before queuing the task; for example, a user agent could
wait for the user to have not hit a key for 100ms, so as to only fire the event when the user
pauses, instead of continuously for each keystroke.
A textarea
element has a dirty value flag, which must be initially set to false, and must be set to true whenever the user
interacts with the control in a way that changes the raw
value.
When the textarea
element’s textContent
IDL attribute changes value,
if the element’s dirty value flag is false, then the
element’s raw value must be set to the value of
the element’s textContent
IDL attribute.
The reset algorithm for textarea
elements is to set the element’s raw value to the
value of the element’s textContent
IDL attribute.
When a textarea
element is popped off the stack of open elements of
an HTML parser or XML parser, then the user agent must invoke the
element’s reset algorithm.
If the element is mutable, the user agent should allow the user to change the writing direction of the element, setting it either to a left-to-right writing direction or a right-to-left writing direction. If the user does so, the user agent must then run the following steps:
- Set the element’s
dir
attribute to "ltr
" if the user selected a left-to-right writing direction, and "rtl
" if the user selected a right-to-left writing direction. - Queue a task to fire a simple event that bubbles named
input
at thetextarea
element.
The cols
attribute specifies the expected
maximum number of characters per line. If the cols
attribute is specified, its value must be a valid non-negative integer greater than
zero. If applying the rules for parsing non-negative integers to
the attribute’s value results in a number greater than zero, then the element’s character width is that value; otherwise, it is 20.
The user agent may use the textarea
element’s character width as a hint to the user as to how many
characters the server prefers per line (e.g., for visual user agents by making the width of the
control be that many characters). In visual renderings, the user agent should wrap the user’s
input in the rendering so that each line is no wider than this number of characters.
The rows
attribute specifies the number of
lines to show. If the rows
attribute is specified, its
value must be a valid non-negative integer greater than zero. If
applying the rules for parsing non-negative integers to the attribute’s value results
in a number greater than zero, then the element’s character
height is that value; otherwise, it is 2.
Visual user agents should set the height of the control to the number of lines given by character height.
The wrap
attribute is an enumerated
attribute with two keywords and states: the soft
keyword which maps to the Soft state, and the hard
keyword which maps to the Hard state. The missing value default is the Soft state.
The Soft state indicates that the text in the textarea
is not to be wrapped when it is submitted (though it can still be wrapped in
the rendering).
The Hard state indicates that the text in the textarea
is to have newlines added by the user agent so that the text is wrapped when
it is submitted.
If the element’s wrap
attribute is in the Hard state, the cols
attribute must be specified.
For historical reasons, the element’s value is normalized in three different ways for three
different purposes. The raw value is the value as
it was originally set. It is not normalized. The API
value is the value used in the value
IDL
attribute. It is normalized so that line breaks use U+000A LINE FEED (LF) characters. Finally,
there is the value, as used in form submission and other
processing models in this specification. It is normalized so that line breaks use U+000D CARRIAGE
RETURN U+000A LINE FEED (CRLF) character pairs, and in addition, if necessary given the element’s wrap
attribute, additional line breaks are inserted to
wrap the text at the given width.
The element’s API value is defined to be the element’s raw value with the following transformation applied:
- Replace every U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pair from the raw value with a single U+000A LINE FEED (LF) character.
- Replace every remaining U+000D CARRIAGE RETURN character from the raw value with a single U+000A LINE FEED (LF) character.
The element’s value is defined to be the element’s raw value with the textarea wrapping transformation applied. The textarea wrapping transformation is the following algorithm, as applied to a string:
- Replace every occurrence of a U+000D CARRIAGE RETURN (CR) character not followed by a U+000A LINE FEED (LF) character, and every occurrence of a U+000A LINE FEED (LF) character not preceded by a U+000D CARRIAGE RETURN (CR) character, by a two-character string consisting of a U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pair.
- If the element’s
wrap
attribute is in the Hard state, insert U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pairs into the string using a user agent-defined algorithm so that each line has no more than character width characters. For the purposes of this requirement, lines are delimited by the start of the string, the end of the string, and U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pairs.
The maxlength
attribute is a form control maxlength
attribute controlled
by the textarea
element’s dirty value flag.
If the textarea
element has a maximum allowed value length, then the
element’s children must be such that the code-unit length of the value of the
element’s textContent
IDL attribute with the textarea wrapping
transformation applied is equal to or less than the element’s maximum allowed value
length.
The minlength
attribute is a form control minlength
attribute controlled by the textarea
element’s dirty value flag.
The required
attribute is a boolean attribute. When specified, the user will be required to enter a value before
submitting the form.
Constraint validation: If the element has its required
attribute specified, and the element is mutable, and the element’s value is the empty string, then the element is suffering
from being missing.
The placeholder
attribute represents
a short hint (a word or short phrase) intended to aid the user with data entry when the
control has no value. A hint could be a sample value or a brief description of the expected
format.
The placeholder
attribute
should not be used as a replacement for a label
. For a
longer hint or other advisory text, place the text next to the control.
Use of the placeholder
attribute as a replacement for a label
can reduce the
accessibility and usability of the control for a range of users including older
users and users with cognitive, mobility, fine motor skill or vision impairments.
While the hint given by the control’s label
is shown at all times, the short
hint given in the placeholder
attribute is only shown before the user enters a value. Furthermore, placeholder
text may be mistaken for
a pre-filled value, and as commonly implemented the default color of the placeholder text
provides insufficient contrast and the lack of a separate visible label
reduces the size of the hit region available for setting focus on the control.
User agents should present this hint to the user when the element’s value is the empty string and the control is not focused (e.g., by displaying it inside a blank unfocused control). All U+000D CARRIAGE RETURN U+000A LINE FEED character pairs (CRLF) in the hint, as well as all other U+000D CARRIAGE RETURN (CR) and U+000A LINE FEED (LF) characters in the hint, must be treated as line breaks when rendering the hint.
The name
attribute represents the element’s name.
The dirname
attribute controls how the element’s directionality is submitted.
The disabled
attribute is used to make the control non-interactive and to prevent its
value from being submitted.
The form
attribute is used to explicitly associate the textarea
element with its form owner.
The autofocus
attribute controls focus.
The inputmode
attribute controls the user interface’s input
modality for the control.
The autocomplete
attribute controls how the user agent provides autofill behavior.
- textarea .
type
-
Returns the string "
textarea
". - textarea .
value
-
Returns the current value of the element.
Can be set, to change the value.
cols
, placeholder
, required
, rows
, and wrap
attributes must reflect the respective content attributes of the same name. The cols
and rows
attributes are limited to only non-negative numbers
greater than zero. The cols
attribute’s default value is 20. The rows
attribute’s default value is 2. The dirName
IDL
attribute must reflect the dirname
content attribute. The inputMode
IDL attribute must reflect the inputmode
content attribute, limited to only known values. The maxLength
IDL attribute must reflect the maxlength
content attribute, limited to only non-negative numbers. The minLength
IDL attribute
must reflect the minlength
content attribute, limited to only non-negative numbers. The readOnly
IDL attribute
must reflect the readonly
content attribute.
The type
IDL attribute must return the value "textarea
".
The defaultValue
IDL attribute must act like the element’s textContent
IDL attribute.
The value
attribute must, on getting, return the element’s API value; on setting, it must set the element’s raw value to the new value, set
the element’s dirty value flag to true, and should then move the text entry cursor
position to the end of the text field, unselecting any selected text and resetting the selection
direction to none.
The textLength
IDL attribute must return the code-unit length of
the element’s API value.
The willValidate
, validity
, and validationMessage
IDL attributes,
and the checkValidity()
, reportValidity()
, and setCustomValidity()
methods, are part of the constraint validation API.
The labels
IDL attribute provides a list of the element’s label
s.
The select()
, selectionStart
, selectionEnd
, selectionDirection
, setRangeText()
, and setSelectionRange()
methods and IDL
attributes expose the element’s text selection.
The autofocus
, disabled
, form
, and name
IDL attributes are part of the element’s forms API.
textarea
being used for unrestricted free-form text input
in a form:
<p>If you have any comments, please let us know: <textarea cols=80 name=comments></textarea></p>
To specify a maximum length for the comments, one can use the maxlength
attribute:
<p>If you have any short comments, please let us know: <textarea cols=80 name=comments maxlength=200></textarea></p>
To give a default value, text can be included inside the element:
<p>If you have any comments, please let us know: <textarea cols=80 name=comments>You rock!</textarea></p>
You can also give a minimum length. Here, a letter needs to be filled out by the user; a template (which is shorter than the minimum length) is provided, but is insufficient to submit the form:
<textarea required minlength="500">Dear Madam Speaker, Regarding your letter dated ... ... Yours Sincerely, ...</textarea>
A placeholder can be given as well, to suggest the basic form to the user, without providing an explicit template:
<textarea placeholder="Dear Francine, They closed the parks this week, so we won’t be able to meet your there. Should we just have dinner? Love, Daddy"></textarea>
To have the browser submit the directionality of the element along with the
value, the dirname
attribute can be specified:
<p>If you have any comments, please let us know (you may use either English or Hebrew for your comments): <textarea cols=80 name=comments dirname=comments.dir></textarea></p>
4.10.12. The keygen
element
- Categories:
- Flow content.
- Phrasing content.
- Interactive content.
- listed, labelable, submittable, resettable, and reassociateable form-associated element.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag.
- Content attributes:
- Global attributes
autofocus
- Automatically focus the form control when the page is loadedchallenge
- String to package with the generated and signed public keydisabled
- Whether the form control is disabledform
- Associates the control with aform
elementkeytype
- The type of cryptographic key to generatename
- Name of form control to use for §4.10.22 Form submission and in theform.elements
API - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLKeygenElement : HTMLElement { attribute boolean autofocus; attribute DOMString challenge; attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute DOMString keytype; attribute DOMString name; readonly attribute DOMString type; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; };
This feature is in the process of being removed from the Web platform. (This
is a long process that takes many years.) Using the keygen
element at this time is
highly discouraged.
The keygen
element represents a key pair generator control. When the
control’s form is submitted, the private key is stored in the local keystore, and the public key
is packaged and sent to the server.
The challenge
attribute may be specified.
Its value will be packaged with the submitted key.
The keytype
attribute is an enumerated attribute. The following table lists the keywords and states for the
attribute — the keywords in the left column map to the states listed in the cell in the
second column on the same row as the keyword. User agents are not required to support these
values, and must only recognize values whose corresponding algorithms they support.
Keyword | State |
---|---|
rsa
| RSA |
The invalid value default state is the unknown state. The missing value default state is the RSA state, if it is supported, or the unknown state otherwise.
This specification does not specify what key types user agents are to support — it is possible for a user agent to not support any key types at all.
The user agent may expose a user interface for each keygen
element to allow the
user to configure settings of the element’s key pair generator, e.g., the key length.
The reset algorithm for keygen
elements is to set these various configuration settings back to their defaults.
The element’s value is the string returned from the following algorithm:
-
Use the appropriate step from the following list:
- If the
keytype
attribute is in the RSA state -
Generate an RSA key pair using the settings given by the user, if appropriate, using the
md5WithRSAEncryption
RSA signature algorithm (the signature algorithm with MD5 and the RSA encryption algorithm) referenced in section 2.2.1 ("RSA Signature Algorithm") of RFC 3279, and defined in RFC 3447. [RFC3279] [RFC3447] - Otherwise, the
keytype
attribute is in the unknown state -
The given key type is not supported. Return the empty string and abort this algorithm.
Let private key be the generated private key.
Let public key be the generated public key.
Let signature algorithm be the selected signature algorithm.
- If the
-
If the element has a
challenge
attribute, then let challenge be that attribute’s value. Otherwise, let challenge be the empty string. -
Let algorithm be an ASN.1
AlgorithmIdentifier
structure as defined by RFC 5280, with thealgorithm
field giving the ASN.1 OID used to identify signature algorithm, using the OIDs defined in section 2.2 ("Signature Algorithms") of RFC 3279, and theparameters
field set up as required by RFC 3279 forAlgorithmIdentifier
structures for that algorithm. [X690] [RFC5280] [RFC3279] -
Let spki be an ASN.1
SubjectPublicKeyInfo
structure as defined by RFC 5280, with thealgorithm
field set to the algorithm structure from the previous step, and thesubjectPublicKey
field set to the BIT STRING value resulting from ASN.1 DER encoding the public key. [X690] [RFC5280] -
Let publicKeyAndChallenge be an ASN.1
PublicKeyAndChallenge
structure as defined below, with thespki
field set to the spki structure from the previous step, and thechallenge
field set to the string challenge obtained earlier. [X690] -
Let signature be the BIT STRING value resulting from ASN.1 DER encoding the signature generated by applying the signature algorithm to the byte string obtained by ASN.1 DER encoding the publicKeyAndChallenge structure, using private key as the signing key. [X690]
-
Let signedPublicKeyAndChallenge be an ASN.1
SignedPublicKeyAndChallenge
structure as defined below, with thepublicKeyAndChallenge
field set to the publicKeyAndChallenge structure, thesignatureAlgorithm
field set to the algorithm structure, and thesignature
field set to the BIT STRING signature from the previous step. [X690] -
Return the result of base64 encoding the result of ASN.1 DER encoding the signedPublicKeyAndChallenge structure. [RFC4648] [X690]
The data objects used by the above algorithm are defined as follows. These definitions use the same "ASN.1-like" syntax defined by RFC 5280. [RFC5280]
PublicKeyAndChallenge ::= SEQUENCE { spki SubjectPublicKeyInfo, challenge IA5STRING } SignedPublicKeyAndChallenge ::= SEQUENCE { publicKeyAndChallenge PublicKeyAndChallenge, signatureAlgorithm AlgorithmIdentifier, signature BIT STRING }
Constraint validation: The keygen
element is barred from
constraint validation.
The form
attribute is used to explicitly associate the keygen
element with its form owner. The name
attribute represents the element’s name. The disabled
attribute is used to make the control non-interactive and
to prevent its value from being submitted. The autofocus
attribute controls focus.
- keygen .
type
-
Returns the string "
keygen
".
The challenge
IDL attribute must reflect the content attribute of the same name.
The keytype
IDL attribute must reflect the content attribute of the same name, limited to only known values.
The type
IDL attribute must return the value
"keygen
".
The willValidate
, validity
, and validationMessage
IDL attributes, and
the checkValidity()
, reportValidity()
, and setCustomValidity()
methods, are part of
the constraint validation API.
The labels
IDL attribute provides a list of the element’s label
s.
The autofocus
, disabled
, form
, and name
IDL attributes are
part of the element’s forms API.
This specification does not specify how the private key generated is to be used.
It is expected that after receiving the SignedPublicKeyAndChallenge
(SPKAC)
structure, the server will generate a client certificate and offer it back to the user for
download; this certificate, once downloaded and stored in the key store along with the private
key, can then be used to authenticate to services that use TLS and certificate authentication. For
more information, see e.g., this MDN article.
<form action="processkey.cgi" method="post" enctype="multipart/form-data"> <p><keygen name="key"></p> <p><input type=submit value="Submit key..."></p> </form>
The server will then receive a form submission with a packaged RSA public key as the value of
"key
". This can then be used for various purposes, such as generating a
client certificate, as mentioned above.
4.10.13. The output
element
- Categories:
- Flow content.
- Phrasing content.
- listed, labelable, resettable, and reassociateable form-associated element.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
for
- Specifies controls from which the output was calculatedform
- Associates the control with aform
elementname
- Name of form control to use for §4.10.22 Form submission and in theform.elements
API - Allowed ARIA role attribute values:
status
(default - do not set), Any role value.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLOutputElement : HTMLElement { [SameObject, PutForwards=value] readonly attribute DOMTokenList htmlFor; readonly attribute HTMLFormElement? form; attribute DOMString name; readonly attribute DOMString type; attribute DOMString defaultValue; attribute DOMString value; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; };
The output
element represents the result of a calculation performed
by the application, or the result of a user action.
This element can be contrasted with the samp
element, which is the
appropriate element for quoting the output of other programs run previously.
The for
content attribute allows an explicit
relationship to be made between the result of a calculation and the elements that represent the
values that went into the calculation or that otherwise influenced the calculation. The for
attribute, if specified, must contain a string consisting of
an unordered set of unique space-separated tokens that are case-sensitive, each of which must have the value of an ID of an element in the same Document
.
The form
attribute is used to explicitly associate the output
element with its form owner. The name
attribute represents the element’s name. The output
element is associated with a form so that it can be easily referenced from the event handlers of
form controls; the element’s value itself is not submitted when the form is submitted.
The element has a value mode flag which is either value or default. Initially, the value mode flag must be set to default.
The element also has a default value. Initially, the default value must be the empty string.
When the value mode flag is in mode default, the contents of the element represent both
the value of the element and its default value.
When the value mode flag is in mode value, the contents of the element represent the
value of the element only, and the default value is only accessible using the defaultValue
IDL
attribute.
Whenever the element’s descendants are changed in any way, if the value mode flag is in mode default, the element’s default value must be set to the value of the
element’s textContent
IDL attribute.
The reset algorithm for output
elements is to set the element’s value mode flag to default and then to set the element’s textContent
IDL attribute to the value of the element’s default value (thus replacing the element’s child
nodes).
- output .
value
[ = value ] -
Returns the element’s current value.
Can be set, to change the value.
- output .
defaultValue
[ = value ] -
Returns the element’s current default value.
Can be set, to change the default value.
- output .
type
-
Returns the string "
output
".
The value
IDL attribute must act like the
element’s textContent
IDL attribute, except that on setting, in addition, before the
child nodes are changed, the element’s value mode flag must be set to value.
The defaultValue
IDL attribute, on
getting, must return the element’s default
value. On setting, the attribute must set the element’s default value, and, if the element’s value mode flag is in the mode default, set the element’s textContent
IDL
attribute as well.
The type
attribute must return the string
"output
".
The htmlFor
IDL attribute must reflect the for
content attribute.
The willValidate
, validity
, and validationMessage
IDL attributes, and
the checkValidity()
, reportValidity()
, and setCustomValidity()
methods, are part of
the constraint validation API.
The labels
IDL attribute provides a list of the element’s label
s.
The form
and name
IDL attributes are
part of the element’s forms API.
output
for its display of calculated results:
<form onsubmit="return false" oninput="o.value = a.valueAsNumber + b.valueAsNumber"> <input name=a type=number step=any> + <input name=b type=number step=any> = <output name=o for="a b"></output> </form>
output
element is used to report the results of a calculation performed by a remote
server, as they come in:
<output id="result"></output> <script> var primeSource = new WebSocket('ws://primes.example.net/'); primeSource.onmessage = function (event) { document.getElementById('result').value = event.data; } </script>
4.10.14. The progress
element
- Categories:
- Flow content.
- Phrasing content.
- Labelable element.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content, but there must be no
progress
element descendants. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
value
- Current value of the elementmax
- Upper bound of range - Allowed ARIA role attribute values:
progressbar
(default - do not set).- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLProgressElement : HTMLElement { attribute double value; attribute double max; readonly attribute double position; [SameObject] readonly attribute NodeList labels; };
The progress
element represents the completion progress of a task.
The progress is either indeterminate, indicating that progress is being made but that it is not
clear how much more work remains to be done before the task is complete (e.g., because the task is
waiting for a remote host to respond), or the progress is a number in the range zero to a maximum,
giving the fraction of work that has so far been completed.
There are two attributes that determine the current task completion represented by the element.
The value
content attribute specifies how much of the
task has been completed, and the max
content attribute
specifies how much work the task requires in total. The units are arbitrary and not specified.
To make a determinate progress bar, add a value
attribute with the current progress (either a number from
0.0 to 1.0, or, if the max
attribute is specified, a number
from 0 to the value of the max
attribute). To make an
indeterminate progress bar, remove the value
attribute.
Authors are encouraged to also include the current value and the maximum value inline as text inside the element, so that the progress is made available to users of legacy user agents.
<section> <h2>Task Progress</h2> <p>Progress: <progress id="p" max=100><span>0</span>%</progress></p> <script> var progressBar = document.getElementById('p'); function updateProgress(newValue) { progressBar.value = newValue; progressBar.getElementsByTagName('span')[0].textContent = newValue; } </script> </section>
(The updateProgress()
method in this example would be called by some
other code on the page to update the actual progress bar as the task progressed.)
The value
and max
attributes, when present, must have values that are valid floating-point numbers. The value
attribute, if present, must have a value equal to or
greater than zero, and less than or equal to the value of the max
attribute, if present, or 1.0, otherwise. The max
attribute, if present, must have a value greater than
zero.
The progress
element is the wrong element to use for something that
is just a gauge, as opposed to task progress. For instance, indicating disk space usage using progress
would be inappropriate. Instead, the meter
element is available
for such use cases.
User agent requirements: If the value
attribute is omitted, then the progress bar is an indeterminate progress bar. Otherwise, it is a
determinate progress bar.
If the progress bar is a determinate progress bar and the element has a max
attribute, the user agent must parse the max
attribute’s value according to the rules for parsing
floating-point number values. If this does not result in an error, and if the parsed value
is greater than zero, then the maximum value of the
progress bar is that value. Otherwise, if the element has no max
attribute, or if it has one but parsing it resulted in an
error, or if the parsed value was less than or equal to zero, then the maximum value of the progress bar is 1.0.
If the progress bar is a determinate progress bar, user agents must parse the value
attribute’s value according to the rules for
parsing floating-point number values. If this does not result in an error, and if the
parsed value is less than the maximum value and
greater than zero, then the current value of the
progress bar is that parsed value. Otherwise, if the parsed value was greater than or equal to the maximum value, then the current value of the progress bar is the maximum value of the progress bar. Otherwise, if parsing
the value
attribute’s value resulted in an error, or a
number less than or equal to zero, then the current
value of the progress bar is zero.
user agent requirements for showing the progress bar: When representing a progress
element to the user, the user agent should indicate whether it is a determinate or
indeterminate progress bar, and in the former case, should indicate the relative position of the current value relative to the maximum value.
- progress .
position
-
For a determinate progress bar (one with known current and maximum values), returns the result of dividing the current value by the maximum value.
For an indeterminate progress bar, returns -1.
If the progress bar is an indeterminate progress bar, then the position
IDL attribute must return -1.
Otherwise, it must return the result of dividing the current
value by the maximum value.
If the progress bar is an indeterminate progress bar, then the value
IDL attribute, on getting, must return 0.
Otherwise, it must return the current value. On
setting, the given value must be converted to the best representation of the number as a floating-point number and then the value
content attribute must be set to that string.
Setting the value
IDL attribute to itself
when the corresponding content attribute is absent would change the progress bar from an
indeterminate progress bar to a determinate progress bar with no progress.
The max
IDL attribute must reflect the content attribute of the same name, limited to numbers greater than
zero. The default value for max
is 1.0.
The labels
IDL attribute provides a list of the element’s label
s.
4.10.15. The meter
element
- Categories:
- Flow content.
- Phrasing content.
- Labelable element.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content, but there must be no
meter
element descendants. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
value
- Current value of the elementmin
- Lower bound of rangemax
- Upper bound of rangelow
- High limit of low rangehigh
- Low limit of high rangeoptimum
- Optimum value in gauge - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLMeterElement : HTMLElement { attribute double value; attribute double min; attribute double max; attribute double low; attribute double high; attribute double optimum; [SameObject] readonly attribute NodeList labels; };
The meter
element represents a scalar measurement within a known
range, or a fractional value; for example disk usage, the relevance of a query result, or the
fraction of a voting population to have selected a particular candidate.
This is also known as a gauge.
The meter
element should not be used to indicate progress (as in a
progress bar). For that role, HTML provides a separate progress
element.
The meter
element also does not represent a scalar value of arbitrary
range — for example, it would be wrong to use this to report a weight, or height, unless
there is a known maximum value.
There are six attributes that determine the semantics of the gauge represented by the element.
The min
attribute specifies the lower bound of
the range, and the max
attribute specifies the
upper bound. The value
attribute specifies the
value to have the gauge indicate as the "measured" value.
The other three attributes can be used to segment the gauge’s range into "low", "medium", and
"high" parts, and to indicate which part of the gauge is the "optimum" part. The low
attribute specifies the range that is considered to
be the "low" part, and the high
attribute
specifies the range that is considered to be the "high" part. The optimum
attribute gives the position that is
"optimum"; if that is higher than the "high" value then this indicates that the higher the value,
the better; if it’s lower than the "low" mark then it indicates that lower values are better, and
naturally if it is in between then it indicates that neither high nor low values are good.
Authoring requirements: The value
attribute must be specified. The value
, min
, low
, high
, max
, and optimum
attributes,
when present, must have values that are valid
floating-point numbers.
In addition, the attributes' values are further constrained:
Let value be the value
attribute’s
number.
If the min
attribute is specified, then let minimum be that attribute’s value; otherwise, let it be zero.
If the max
attribute is specified, then let maximum be that attribute’s value; otherwise, let it be 1.0.
The following inequalities must hold, as applicable:
- minimum ≤ value ≤ maximum
- minimum ≤
low
≤ maximum (iflow
is specified) - minimum ≤
high
≤ maximum (ifhigh
is specified) - minimum ≤
optimum
≤ maximum (ifoptimum
is specified) low
≤high
(if bothlow
andhigh
are specified)
If no minimum or maximum is specified, then the range is assumed to be 0..1, and the value thus has to be within that range.
Authors are encouraged to include a textual representation of the gauge’s state in the
element’s contents, for users of user agents that do not support the meter
element.
When used with microdata, the meter
element’s value
attribute provides the element’s machine-readable value.
Storage space usage: <meter value=6 max=8>6 blocks used (out of 8 total)</meter> Voter turnout: <meter value=0.75><img alt="75%" src="graph75.png"></meter> Tickets sold: <meter min="0" max="100" value="75"></meter>
The following example is incorrect use of the element, because it doesn’t give a range (and since the default maximum is 1, both of the gauges would end up looking maxed out):
<p>The grapefruit pie had a radius of <meter value=12>12cm</meter>and a height of <meter value=2>2cm</meter>.</p> <!-- BAD! -->
Instead, one would either not include the meter element, or use the meter element with a defined range to give the dimensions in context compared to other pies:
<p>The grapefruit pie had a radius of 12cm and a height of 2cm.</p> <dl> <dt>Radius: <dd> <meter min=0 max=20 value=12>12cm</meter> <dt>Height: <dd> <meter min=0 max=10 value=2>2cm</meter> </dl>
There is no explicit way to specify units in the meter
element, but the units may
be specified in the title
attribute in free-form text.
<dl> <dt>Radius: <dd> <meter min=0 max=20 value=12 title="centimeters">12cm</meter> <dt>Height: <dd> <meter min=0 max=10 value=2 title="centimeters">2cm</meter> </dl>
User agent requirements: User agents must parse the min
, max
, value
, low
, high
, and optimum
attributes using the rules for parsing floating-point number values.
User agents must then use all these numbers to obtain values for six points on the gauge, as follows. (The order in which these are evaluated is important, as some of the values refer to earlier ones.)
- The minimum value
-
If the
min
attribute is specified and a value could be parsed out of it, then the minimum value is that value. Otherwise, the minimum value is zero. - The maximum value
-
If the
max
attribute is specified and a value could be parsed out of it, then the candidate maximum value is that value. Otherwise, the candidate maximum value is 1.0.If the candidate maximum value is greater than or equal to the minimum value, then the maximum value is the candidate maximum value. Otherwise, the maximum value is the same as the minimum value.
- The actual value
-
If the
value
attribute is specified and a value could be parsed out of it, then that value is the candidate actual value. Otherwise, the candidate actual value is zero.If the candidate actual value is less than the minimum value, then the actual value is the minimum value.
Otherwise, if the candidate actual value is greater than the maximum value, then the actual value is the maximum value.
Otherwise, the actual value is the candidate actual value.
- The low boundary
-
If the
low
attribute is specified and a value could be parsed out of it, then the candidate low boundary is that value. Otherwise, the candidate low boundary is the same as the minimum value.If the candidate low boundary is less than the minimum value, then the low boundary is the minimum value.
Otherwise, if the candidate low boundary is greater than the maximum value, then the low boundary is the maximum value.
Otherwise, the low boundary is the candidate low boundary.
- The high boundary
-
If the
high
attribute is specified and a value could be parsed out of it, then the candidate high boundary is that value. Otherwise, the candidate high boundary is the same as the maximum value.If the candidate high boundary is less than the low boundary, then the high boundary is the low boundary.
Otherwise, if the candidate high boundary is greater than the maximum value, then the high boundary is the maximum value.
Otherwise, the high boundary is the candidate high boundary.
- The optimum point
-
If the
optimum
attribute is specified and a value could be parsed out of it, then the candidate optimum point is that value. Otherwise, the candidate optimum point is the midpoint between the minimum value and the maximum value.If the candidate optimum point is less than the minimum value, then the optimum point is the minimum value.
Otherwise, if the candidate optimum point is greater than the maximum value, then the optimum point is the maximum value.
Otherwise, the optimum point is the candidate optimum point.
All of which will result in the following inequalities all being true:
- minimum value ≤ actual value ≤ maximum value
- minimum value ≤ low boundary ≤ high boundary ≤ maximum value
- minimum value ≤ optimum point ≤ maximum value
user agent requirements for regions of the gauge: If the optimum point is equal to the low boundary or the high boundary, or anywhere in between them, then the region between the low and high boundaries of the gauge must be treated as the optimum region, and the low and high parts, if any, must be treated as suboptimal. Otherwise, if the optimum point is less than the low boundary, then the region between the minimum value and the low boundary must be treated as the optimum region, the region from the low boundary up to the high boundary must be treated as a suboptimal region, and the remaining region must be treated as an even less good region. Finally, if the optimum point is higher than the high boundary, then the situation is reversed; the region between the high boundary and the maximum value must be treated as the optimum region, the region from the high boundary down to the low boundary must be treated as a suboptimal region, and the remaining region must be treated as an even less good region.
user agent requirements for showing the gauge: When representing a meter
element to the user, the user agent should indicate the relative position of the actual value to the
minimum and maximum values, and the relationship between the actual value and the three regions of
the gauge.
User agents may combine the value of the title
attribute and the other attributes to provide context-sensitive
help or inline text detailing the actual values.
<meter min=0 max=60 value=23.2 title=seconds></meter>
...might cause the user agent to display a gauge with a tooltip saying "Value: 23.2 out of 60." on one line and "seconds" on a second line.
The value
IDL attribute, on getting, must
return the actual value. On setting, the given value
must be converted to the best representation of the number as a floating-point number and then the value
content attribute must be set to that string.
The min
IDL attribute, on getting, must return
the minimum value. On setting, the given value must be
converted to the best representation of the number as a floating-point number and then the min
content attribute must be set to that string.
The max
IDL attribute, on getting, must return
the maximum value. On setting, the given value must be
converted to the best representation of the number as a floating-point number and then the max
content attribute must be set to that string.
The low
IDL attribute, on getting, must return
the low boundary. On setting, the given value must be
converted to the best representation of the number as a floating-point number and then the low
content attribute must be set to that string.
The high
IDL attribute, on getting, must return
the high boundary. On setting, the given value must be
converted to the best representation of the number as a floating-point number and then the high
content attribute must be set to that string.
The optimum
IDL attribute, on getting, must
return the optimum value. On setting, the given value
must be converted to the best representation of the number as a floating-point number and then the optimum
content attribute must be set to that string.
The labels
IDL attribute provides a list of the element’s label
s.
<p>Disk usage: <meter min=0 value=170261928 max=233257824>170 261 928 bytes used out of 233 257 824 bytes available</meter></p>
4.10.16. The fieldset
element
- Categories:
- Flow content.
- Sectioning root.
- listed and reassociateable form-associated element.
- Palpable content.
- Sectioning root.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Optionally a
legend
element, followed by flow content. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
disabled
- Whether the form control is disabledform
- Associates the control with aform
elementname
- Name of form control to use for §4.10.22 Form submission and in theform.elements
API - Allowed ARIA role attribute values:
group
(default - do not set) orpresentation
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLFieldSetElement : HTMLElement { attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute DOMString name; readonly attribute DOMString type; [SameObject] readonly attribute HTMLCollection elements; readonly attribute boolean willValidate; [SameObject] readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); };
The fieldset
element represents a set of form controls optionally
grouped under a common name.
The name of the group is given by the first legend
element that is a child of the fieldset
element, if any. The remainder of the descendants form the group.
The disabled
attribute, when specified,
causes all the form control descendants of the fieldset
element, excluding those that
are descendants of the fieldset
element’s first legend
element child, if
any, to be disabled.
A fieldset
element is a disabled fieldset if it matches any of the following conditions:
- Its
disabled
attribute is specified - It is a descendant of another
fieldset
element whosedisabled
attribute is specified, and is not a descendant of thatfieldset
element’s firstlegend
element child, if any.
The form
attribute is used to explicitly associate the fieldset
element with its form owner. The name
attribute represents the element’s name.
- fieldset .
type
-
Returns the string "fieldset".
- fieldset .
elements
-
Returns an
HTMLCollection
of the form controls in the element.
The disabled
IDL attribute must reflect the content attribute of the same name.
The type
IDL attribute must return the string
"fieldset
".
The elements
IDL attribute must return an HTMLCollection
rooted at the fieldset
element, whose filter
matches listed elements.
The willValidate
, validity
, and validationMessage
attributes, and the checkValidity()
, reportValidity()
, and setCustomValidity()
methods, are part of
the constraint validation API. The form
and name
IDL attributes are part of the
element’s forms API.
fieldset
element being used to group a set of related
controls:
<fieldset> <legend>Display</legend> <p><label><input type=radio name=c value=0 checked> Black on White</label> <p><label><input type=radio name=c value=1> White on Black</label> <p><label><input type=checkbox name=g> Use grayscale</label> <p><label>Enhance contrast <input type=range name=e list=contrast min=0 max=100 value=0 step=1></label> <datalist id=contrast> <option label=Normal value=0> <option label=Maximum value=100> </datalist> </fieldset>
<fieldset name="clubfields" disabled> <legend> <label> <input type=checkbox name=club onchange="form.clubfields.disabled = !checked"> Use Club Card </label> </legend> <p><label>Name on card: <input name=clubname required></label></p> <p><label>Card number: <input name=clubnum required pattern="[-0-9]+"></label></p> <p><label>Expiry date: <input name=clubexp type=month></label></p> </fieldset>
fieldset
elements. Here is an example expanding on the previous
one that does so:
<fieldset name="clubfields" disabled> <legend> <label> <input type=checkbox name=club onchange="form.clubfields.disabled = !checked"> Use Club Card </label> </legend> <p><label>Name on card: <input name=clubname required></label></p> <fieldset name="numfields"> <legend> <label> <input type=radio checked name=clubtype onchange="form.numfields.disabled = !checked"> My card has numbers on it </label> </legend> <p><label>Card number: <input name=clubnum required pattern="[-0-9]+"></label></p> </fieldset> <fieldset name="letfields" disabled> <legend> <label> <input type=radio name=clubtype onchange="form.letfields.disabled = !checked"> My card has letters on it </label> </legend> <p><label>Card code: <input name=clublet required pattern="[A-Za-z]+"></label></p> </fieldset> </fieldset>
In this example, if the outer "Use Club Card" checkbox is not checked, everything inside the
outer fieldset
, including the two radio buttons in the legends of the two nested fieldset
s, will be disabled. However, if the checkbox is checked, then the radio
buttons will both be enabled and will let you select which of the two inner fieldset
s is to be enabled.
4.10.17. The legend
element
- Categories:
- None.
- Contexts in which this element can be used:
- As the first child of a
fieldset
element. - Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLLegendElement : HTMLElement { readonly attribute HTMLFormElement? form; };
The legend
element represents a caption for the rest of the contents
of the legend
element’s parent fieldset
element, if
any.
- legend .
form
-
Returns the element’s
form
element, if any, or null otherwise.
The form
IDL attribute’s behavior depends on
whether the legend
element is in a fieldset
element or not. If the legend
has a fieldset
element as its parent, then the form
IDL attribute must return the same value as the form
IDL attribute on that fieldset
element. Otherwise,
it must return null.
4.10.18. Form control infrastructure
4.10.18.1. A form control value
Most form controls have a value and a checkedness. (The latter is only used by input
elements.) These are used to describe how the user interacts with the control.
A control’s value is its internal state. As such, it might not match the user’s current input.
For instance, if a user enters the word "three" into a numeric field that expects digits, the user’s input would
be the string "three" but the control’s value would remain
unchanged. Or, if a user enters the email address " awesome@example.com"
(with leading whitespace) into an email field, the
user’s input would be the string " awesome@example.com" but the browser’s UI for
email fields might translate that into a value of "awesome@example.com
" (without the leading whitespace).
To define the behavior of constraint validation in the face of the input
element’s multiple
attribute, input
elements
can also have separately defined values.
The select
element does not have a value;
the selectedness of its option
elements is what is used instead.
4.10.18.2. Mutability
A form control can be designated as mutable.
This determines (by means of definitions and requirements in this specification that rely on whether an element is so designated) whether or not the user can modify the value or checkedness of a form control, or whether or not a control can be automatically prefilled.
4.10.18.3. Association of controls and forms
A form-associated element can have a relationship with a form
element, which is called the element’s form owner. If a form-associated
element is not associated with a form
element, its form owner is
said to be null.
A form-associated element is, by default, associated with its nearest ancestor form
element (as described
below), but, if it is reassociateable, may have a form
attribute specified to override this.
This feature allows authors to work around the lack of support for nested form
elements.
If a reassociateable form-associated
element has a form
attribute specified, then that
attribute’s value must be the ID of a form
element
in the element’s owner Document
.
The rules in this section are complicated by the fact that although conforming
documents will never contain nested form
elements, it is quite possible (e.g., using a
script that performs DOM manipulation) to generate documents that have such nested elements. They
are also complicated by rules in the HTML parser that, for historical reasons, can result in a form-associated element being associated with a form
element that is not
its ancestor.
When a form-associated element is created, its form owner must be initialized to null (no owner).
When a form-associated element is to be associated with a form, its form owner must be set to that form.
When a form-associated element or one of its ancestors is inserted into a Document
, then the user agent must reset the form owner of that form-associated element. The HTML parser overrides this requirement when inserting form
controls.
When an element changes its parent node resulting in a form-associated element and its form owner (if any) no longer being in the same home subtree, then the user agent must reset the form owner of that form-associated element.
When a reassociateable form-associated
element’s form
attribute is set, changed, or removed,
then the user agent must reset the form owner of that element.
When a reassociateable form-associated
element has a form
attribute and the ID of any of the elements in the Document
changes, then
the user agent must reset the form owner of that form-associated
element.
When a reassociateable form-associated
element has a form
attribute and an element with an ID is inserted into or removed from the Document
, then the user agent must reset the form owner of that form-associated element.
When the user agent is to reset the form owner of a form-associated element, it must run the following steps:
- If the element’s form owner is not null, and either the element is not reassociateable or its
form
content attribute is not present, and the element’s form owner is its nearestform
element ancestor after the change to the ancestor chain, then do nothing, and abort these steps. - Let the element’s form owner be null.
-
If the element is reassociateable, has a
form
content attribute, and is itself in aDocument
, then run these substeps:- If the first element in the
Document
to have an ID that is case-sensitively equal to the element’sform
content attribute’s value is aform
element, then associate the form-associated element with thatform
element. - Abort the "reset the form owner" steps.
- If the first element in the
- Otherwise, if the form-associated element in question has an ancestor
form
element, then associate the form-associated element with the nearest such ancestorform
element. - Otherwise, the element is left unassociated.
... <form id="a"> <div id="b"></div> </form> <script> document.getElementById('b').innerHTML = '<table><tr><td><form id="c"><input id="d"></table>' + '<input id="e">'; </script> ...
The form owner of "d" would be the inner nested form "c", while the form owner of "e" would be the outer form "a".
This happens as follows: First, the "e" node gets associated with "c" in the HTML
parser. Then, the innerHTML
algorithm moves the nodes
from the temporary document to the "b" element. At this point, the nodes see their ancestor chain
change, and thus all the "magic" associations done by the parser are reset to normal ancestor
associations.
This example is a non-conforming document, though, as it is a violation of the content models
to nest form
elements.
- element .
form
-
Returns the element’s form owner.
Returns null if there isn’t one.
form
IDL attribute, which, on getting, must return the element’s form owner, or null if there
isn’t one. 4.10.19. Attributes common to form controls
4.10.19.1. Naming form controls: the name
attribute
The name
content attribute gives the name of the form control, as used in §4.10.22 Form submission and
in the form
element’s elements
object. If the attribute is specified, its value
must not be the empty string.
Any non-empty value for name
is allowed, but the name
"_charset_
" is special:
-
This value, if used as the name of a
control with novalue
attribute, is automatically given a value during submission consisting of the submission character encoding.
4.10.19.2. Submitting element directionality: the dirname
attribute
The dirname
attribute on a form control
element enables the submission of the directionality of the element, and gives the name of
the field that contains this value during §4.10.22 Form submission. If such an attribute is
specified, its value must not be the empty string.
<form action="addcomment.cgi" method=post> <p><label>Comment: <input type=text name="comment" dirname="comment.dir" required></label></p> <p><button name="mode" type=submit value="add">Post Comment</button></p> </form>
When the user submits the form, the user agent includes three fields, one called "comment", one called "comment.dir", and one called "mode"; so if the user types "Hello", the submission body might be something like:
comment=Hello&comment.dir=ltr&mode=add
If the user manually switches to a right-to-left writing direction and enters "مرحبا", the submission body might be something like:
comment=%D9%85%D8%B1%D8%AD%D8%A8%D8%A7&comment.dir=rtl&mode=add
4.10.19.3. Limiting user input length: the maxlength
attribute
A form control maxlength
attribute,
controlled by a dirty value flag, declares a limit on the number of characters
a user can input.
If an element has its form control maxlength
attribute specified, the attribute’s value must be a valid
non-negative integer. If the attribute is specified and applying the rules for
parsing non-negative integers to its value results in a number, then that number is the
element’s maximum allowed value length. If the attribute is omitted or parsing its
value results in an error, then there is no maximum allowed value length.
Constraint validation: If an element has a maximum allowed value length, its dirty value flag is true, its value was last changed by a user edit (as opposed to a change made by a script), and the code-unit length of the element’s value is greater than the element’s maximum allowed value length, then the element is suffering from being too long.
User agents may prevent the user from causing the element’s value to be set to a value whose code-unit length is greater than the element’s maximum allowed value length.
In the case of textarea
elements, this is the value, not the raw
value, so the textarea wrapping transformation is applied before the maximum allowed value length is checked.
4.10.19.4. Setting minimum input length requirements: the minlength
attribute
A form control minlength
attribute,
controlled by a dirty value flag, declares a lower bound on the number of
characters a user can input.
The minlength
attribute does not imply the required
attribute. If the form control has no required
attribute, then the value can still be omitted; the minlength
attribute only kicks in once the user has entered
a value at all. If the empty string is not allowed, then the required
attribute also needs to be set.
If an element has its form control minlength
attribute specified, the attribute’s value must be a valid
non-negative integer. If the attribute is specified and applying the rules for
parsing non-negative integers to its value results in a number, then that number is the
element’s minimum allowed value length. If the attribute is omitted or parsing its
value results in an error, then there is no minimum allowed value length.
If an element has both a maximum allowed value length and a minimum allowed value length, the minimum allowed value length must be smaller than or equal to the maximum allowed value length.
Constraint validation: If an element has a minimum allowed value length, its dirty value flag is true, its value was last changed by a user edit (as opposed to a change made by a script), its value is not the empty string, and the code-unit length of the element’s value is less than the element’s minimum allowed value length, then the element is suffering from being too short.
<form action="/events/menu.cgi" method="post"> <p><label>Name of Event: <input required minlength=5 maxlength=50 name=event></label></p> <p><label>Describe what you would like for breakfast, if anything: <textarea name="breakfast" minlength="10"></textarea></label></p> <p><label>Describe what you would like for lunch, if anything: <textarea name="lunch" minlength="10"></textarea></label></p> <p><label>Describe what you would like for dinner, if anything: <textarea name="dinner" minlength="10"></textarea></label></p> <p><input type=submit value="Submit Request"></p> </form>
4.10.19.5. Enabling and disabling form controls: the disabled
attribute
The disabled
content attribute is a boolean attribute.
A form control is disabled if any of the following conditions are met:
- The element is a
button
,input
,select
, ortextarea
element, and thedisabled
attribute is specified on this element (regardless of its value). - The element is a descendant of a
fieldset
element whosedisabled
attribute is specified, and is not a descendant of thatfieldset
element’s firstlegend
element child, if any.
A form control that is disabled must prevent any click
events that are queued on the user interaction task source from being dispatched on the element.
Constraint validation: If an element is disabled, it is barred from constraint validation.
The disabled
IDL attribute must reflect the disabled
content attribute.
4.10.19.6. Form submission
Attributes for form submission can be specified both on form
elements
and on submit buttons (elements that represent buttons
that submit forms, e.g., an input
element whose type
attribute is in the submit button state).
The attributes for form submission that may be specified on form
elements are action
, enctype
, method
, novalidate
, and target
.
The corresponding attributes for form submission that may be specified on submit buttons are formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
. When omitted, they default to the values given on
the corresponding attributes on the form
element.
The action
and formaction
content attributes, if specified, must
have a value that is a valid non-empty URL potentially surrounded by spaces.
The action of an element is the value of the element’s formaction
attribute, if the element is a submit button and has such an attribute, or the value of its form owner’s action
attribute, if it has
one, or else the empty string.
The method
and formmethod
content attributes are enumerated attributes with the following keywords and
states:
- The keyword
get
, mapping to the state GET, indicating the HTTP GET method. - The keyword
post
, mapping to the state POST, indicating the HTTP POST method.
The invalid value default for these attributes is the GET state. The missing value default for the method
attribute is also the GET state. (There is no missing value default for the formmethod
attribute.)
The method of an element is one of those states. If the element is a submit button and has a formmethod
attribute, then the element’s method is that attribute’s state; otherwise, it
is the form owner’s method
attribute’s state.
method
attribute is used to explicitly specify
the default value, "get", so that the search
query is submitted in the URL:
<form method="get" action="/search.cgi"> <p><label>Search terms: <input type=search name=q></label></p> <p><input type=submit></p> </form>
method
attribute is used to
specify the value "post", so that the user’s
message is submitted in the HTTP request’s body:
<form method="post" action="/post-message.cgi"> <p><label>Message: <input type=text name=m></label></p> <p><input type=submit value="Submit message"></p> </form>
The enctype
and formenctype
content attributes are enumerated attributes with the following keywords and
states:
- The "
application/x-www-form-urlencoded
" keyword and corresponding state. - The "
multipart/form-data
" keyword and corresponding state. - The "
text/plain
" keyword and corresponding state.
The invalid value default for these attributes is the application/x-www-form-urlencoded
state. The missing value default for the enctype
attribute is also the application/x-www-form-urlencoded
state. (There is no missing value default for the formenctype
attribute.)
The enctype of an element is one of those three states.
If the element is a submit button and has a formenctype
attribute, then the element’s enctype is that attribute’s state; otherwise, it is the form owner’s enctype
attribute’s state.
The target
and formtarget
content attributes, if specified, must
have values that are valid browsing context
names or keywords.
The target
of an element is the value of the element’s formtarget
attribute, if the element is a submit button and has such an attribute; or the value of its form owner’s target
attribute, if it has
such an attribute; or, if the Document
contains a base
element with a target
attribute, then the value of the target
attribute of the first such base
element; or,
if there is no such element, the empty string.
The novalidate
and formnovalidate
content attributes are boolean attributes. If present, they indicate that the form is
not to be validated during submission.
The no-validate state of an element is true if the
element is a submit button and the element’s formnovalidate
attribute is present, or if the element’s form owner’s novalidate
attribute is present,
and false otherwise.
<form action="editor.cgi" method="post"> <p><label>Name: <input required name=fn></label></p> <p><label>Essay: <textarea required name=essay></textarea></label></p> <p><input type=submit name=submit value="Submit essay"></p> <p><input type=submit formnovalidate name=save value="Save essay"></p> <p><input type=submit formnovalidate name=cancel value="Cancel"></p> </form>
The action
IDL attribute must reflect the
content attribute of the same name, except that on getting, when the content attribute is missing
or its value is the empty string, the document’s address must be returned instead.
The target
IDL attribute must reflect the
content attribute of the same name.
The method
and enctype
IDL attributes must reflect the
respective content attributes of the same name, limited to only known values.
The encoding
IDL attribute must reflect the enctype
content attribute, limited to only known values.
The noValidate
IDL attribute must reflect the novalidate
content attribute.
The formAction
IDL attribute must reflect the formaction
content attribute, except that on getting, when the content attribute is
missing or its value is the empty string, the document’s address must be returned instead.
The formEnctype
IDL attribute must reflect the formenctype
content attribute, limited to only known values.
The formMethod
IDL attribute must reflect the formmethod
content attribute, limited to only known values.
The formNoValidate
IDL attribute must reflect the formnovalidate
content attribute.
The formTarget
IDL attribute must reflect the formtarget
content attribute.
4.10.19.6.1. Autofocusing a form control: the autofocus
attribute
The autofocus
content attribute allows the
author to indicate that a control is to be focused as soon as the page is loaded, allowing the user to just start typing
without having to manually focus the main control.
The autofocus
attribute is a boolean attribute.
An element’s nearest ancestor autofocus scoping root element is the element itself if it is the element’s root element.
There must not be two elements with the same nearest ancestor autofocus scoping root
element that both have the autofocus
attribute
specified.
When an element with the autofocus
attribute specified
is inserted into a document, user agents
should run the following steps:
- Let target be the element’s node document.
- If target has no browsing context, abort these steps.
- If target’s browsing context has no top-level browsing context (e.g., it is a nested browsing context with no parent browsing context), abort these steps.
- If target’s active sandboxing flag set has the sandboxed automatic features browsing context flag, abort these steps.
- If target’s origin is not the same as the origin of the node document of the currently focused element in target’s top-level browsing context, abort these steps.
- If target’s origin is not the same as the origin of the active document of target’s top-level browsing context, abort these steps.
- If the user agent has already reached the last step of this list of steps in response to
an element being inserted into a
Document
whose top-level browsing context’s active document is the same as target’s top-level browsing context’s active document, abort these steps. - If the user has indicated (for example, by starting to type in a form control) that he does not wish focus to be changed, then optionally abort these steps.
- Queue a task that runs the focusing steps for the element. User agents may also change the scrolling position of the document, or perform some other action that brings the element to the user’s attention. The task source for this task is the user interaction task source.
Focusing the control does not imply that the user agent must focus the browser window if it has lost focus.
The autofocus
IDL attribute must reflect the content attribute of the same name.
<input maxlength="256" name="q" value="" autofocus> <input type="submit" value="Search">
4.10.19.7. Input modalities: the inputmode
attribute
The inputmode
content attribute is an enumerated attribute that specifies what kind of input mechanism would be most
helpful for users entering content into the form control.
User agents must recognize all the keywords and corresponding states given below, but need not support all of the corresponding states. If a keyword’s state is not supported, the user agent must act as if the keyword instead mapped to the given state’s fallback state, as defined below. This fallback behavior is transitive.
For example, if a user agent with a QWERTY keyboard layout does not support text
prediction and automatic capitalization, then it could treat the latin-prose
keyword in the same way as the verbatim
keyword, following the chain Latin Prose → Latin Text → Latin Verbatim.
The possible keywords and states for the attributes are listed in the following table. The keywords are listed in the first column. Each maps to the state given in the cell in the second column of that keyword’s row, and that state has the fallback state given in the cell in the third column of that row.
Keyword | State | Fallback state | Description |
---|---|---|---|
verbatim
| Latin Verbatim | Default | Alphanumeric Latin-script input of non-prose content, e.g., usernames, passwords, product codes. |
latin
| Latin Text | Latin Verbatim | Latin-script input in the user’s preferred language(s), with some typing aids enabled (e.g., text prediction). Intended for human-to-computer communications, e.g., free-form text search fields. |
latin-name
| Latin Name | Latin Text | Latin-script input in the user’s preferred language(s), with typing aids intended for entering human names enabled (e.g., text prediction from the user’s contact list and automatic capitalization at every word). Intended for situations such as customer name fields. |
latin-prose
| Latin Prose | Latin Text | Latin-script input in the user’s preferred language(s), with aggressive typing aids intended for human-to-human communications enabled (e.g., text prediction and automatic capitalization at the start of sentences). Intended for situations such as e-mails and instant messaging. |
full-width-latin
| Full-width Latin | Latin Prose | Latin-script input in the user’s secondary language(s), using full-width characters, with aggressive typing aids intended for human-to-human communications enabled (e.g., text prediction and automatic capitalization at the start of sentences). Intended for latin text embedded inside CJK text. |
kana
| Kana | Default | Kana or romaji input, typically hiragana input, using full-width characters, with support for converting to kanji. Intended for Japanese text input. |
kana-name
| Kana Name | Kana | Kana or romaji input, typically hiragana input, using full-width characters, with support for converting to kanji, and with typing aids intended for entering human names enabled (e.g., text prediction from the user’s contact list). Intended for situations such as customer name fields. |
katakana
| Katakana | Kana | Katakana input, using full-width characters, with support for converting to kanji. Intended for Japanese text input. |
numeric
| Numeric | Default | Numeric input, including keys for the digits 0 to 9, the user’s preferred thousands
separator character, and the character for indicating negative numbers. Intended for numeric
codes, e.g., credit card numbers. (For numbers, prefer "<input type=number> ".)
|
tel
| Telephone | Numeric | Telephone number input, including keys for the digits 0 to 9, the "#" character, and the
"*" character. In some locales, this can also include alphabetic mnemonic labels (e.g., in the
US, the key labeled "2" is historically also labeled with the letters A, B, and C). Rarely necessary; use "<input
type=tel> " instead.
|
email
| Default | Text input in the user’s locale, with keys for aiding in the input of e-mail addresses,
such as that for the "@" character and the "." character. Rarely
necessary; use "<input type=email> " instead.
| |
url
| URL | Default | Text input in the user’s locale, with keys for aiding in the input of Web addresses, such
as that for the "/" and "." characters and for quick input of strings commonly found in domain
names such as "www." or ".co.uk". Rarely necessary; use "<input type=url> " instead.
|
The last three keywords listed above are only provided for completeness, and are rarely necessary, as dedicated input controls exist for their usual use cases (as described in the table above).
User agents must all support the Default input mode state, which corresponds to the user agent’s default input modality. This specification does not define how the user agent’s default modality is to operate. The missing value default is the Default input mode state.
User agents should use the input modality corresponding to the state of the inputmode
attribute when exposing a user interface for editing
the value of a form control to which the attribute applies. An input modality corresponding to a state is one
designed to fit the description of the state in the table above. This value can change
dynamically; user agents should update their interface as the attribute changes state, unless that
would go against the user’s wishes.
4.10.19.8. Autofill
4.10.19.8.1. Autofilling form controls: the autocomplete
attribute
User agents sometimes have features for helping users fill forms in, for example prefilling the
user’s address based on earlier user input. The autocomplete
content attribute can be used to hint
to the user agent how to, or indeed whether to, provide such a feature.
There are two ways this attribute is used. When wearing the autofill expectation
mantle, the autocomplete
attribute describes what
input is expected from users. When wearing the autofill anchor mantle, the autocomplete
attribute describes the meaning of the given
value.
On an input
element whose type
attribute is
in the state, the autocomplete
attribute wears the autofill anchor
mantle. In all other cases, it wears the autofill expectation mantle.
When wearing the autofill expectation mantle, the autocomplete
attribute, if specified, must have a value that
is an ordered set of space-separated tokens consisting of either a single token that
is an ASCII case-insensitive match for the string "off
", or a single token that is an ASCII
case-insensitive match for the string "on
",
or autofill detail tokens.
When wearing the autofill anchor
mantle, the autocomplete
attribute, if specified, must have a value that is an ordered set of
space-separated tokens consisting of just autofill detail tokens (i.e., the
"on
" and "off
" keywords are not allowed).
Autofill detail tokens are the following, in the order given below:
-
Optionally, a token whose first eight characters are an ASCII case-insensitive match for the string "
section-
", meaning that the field belongs to the named group.For example, if there are two shipping addresses in the form, then they could be marked up as:<fieldset> <legend>Ship the blue gift to...</legend> <p> <label> Address: <input name=ba autocomplete="section-blue shipping street-address"> </label> <p> <label> City: <input name=bc autocomplete="section-blue shipping address-level2"> </label> <p> <label> Postal Code: <input name=bp autocomplete="section-blue shipping postal-code"> </label> </fieldset> <fieldset> <legend>Ship the red gift to...</legend> <p> <label> Address: <input name=ra autocomplete="section-red shipping street-address"> </label> <p> <label> City: <input name=rc autocomplete="section-red shipping address-level2"> </label> <p> <label> Postal Code: <input name=rp autocomplete="section-red shipping postal-code"> </label> </fieldset>
-
Optionally, a token that is an ASCII case-insensitive match for one of the following strings:
-
Either of the following two options:
-
A token that is an ASCII case-insensitive match for one of the following autofill field names, excluding those that are inappropriate for the control:
- "
name
" - "
honorific-prefix
" - "
given-name
" - "
additional-name
" - "
family-name
" - "
honorific-suffix
" - "
nickname
" - "
username
" - "
new-password
" - "
current-password
" - "
organization-title
" - "
organization
" - "
street-address
" - "
address-line1
" - "
address-line2
" - "
address-line3
" - "
address-level4
" - "
address-level3
" - "
address-level2
" - "
address-level1
" - "
country
" - "
country-name
" - "
postal-code
" - "
cc-name
" - "
cc-given-name
" - "
cc-additional-name
" - "
cc-family-name
" - "
cc-number
" - "
cc-exp
" - "
cc-exp-month
" - "
cc-exp-year
" - "
cc-csc
" - "
cc-type
" - "
transaction-currency
" - "
transaction-amount
" - "
language
" - "
bday
" - "
bday-day
" - "
bday-month
" - "
bday-year
" - "
sex
" - "
url
" - "
photo
"
(See the table below for descriptions of these values.)
- "
-
The following, in the given order:
-
Optionally, a token that is an ASCII case-insensitive match for one of the following strings:
- "
home
", meaning the field is for contacting someone at their residence - "
work
", meaning the field is for contacting someone at their workplace - "
mobile
", meaning the field is for contacting someone regardless of location - "
fax
", meaning the field describes a fax machine’s contact details - "
pager
", meaning the field describes a pager’s or beeper’s contact details
- "
-
A token that is an ASCII case-insensitive match for one of the following autofill field names, excluding those that are inappropriate for the control:
- "
tel
" - "
tel-country-code
" - "
tel-national
" - "
tel-area-code
" - "
tel-local
" - "
tel-local-prefix
" - "
tel-local-suffix
" - "
tel-extension
" - "
email
" - "
impp
"
(See the table below for descriptions of these values.)
- "
-
-
As noted earlier, the meaning of the attribute and its keywords depends on the mantle that the attribute is wearing.
- When wearing the autofill expectation mantle...
-
The "
off
" keyword indicates either that the control’s input data is particularly sensitive (for example the activation code for a nuclear weapon); or that it is a value that will never be reused (for example a one-time-key for a bank login) and the user will therefore have to explicitly enter the data each time, instead of being able to rely on the user agent to prefill the value for him; or that the document provides its own autocomplete mechanism and does not want the user agent to provide autocompletion values.The "
on
" keyword indicates that the user agent is allowed to provide the user with autocompletion values, but does not provide any further information about what kind of data the user might be expected to enter. User agents would have to use heuristics to decide what autocompletion values to suggest.The autofill field listed above indicate that the user agent is allowed to provide the user with autocompletion values, and specifies what kind of value is expected. The meaning of each such keyword is described in the table below.
If the
autocomplete
attribute is omitted, the default value corresponding to the state of the element’s form owner’sautocomplete
attribute is used instead (either "on
" or "off
"). If there is no form owner, then the value "on
" is used. - When wearing the autofill anchor mantle...
-
The autofill field listed above indicate that the value of the particular kind of value specified is that value provided for this element. The meaning of each such keyword is described in the table below.
In this example the page has explicitly specified the currency and amount of the transaction. The form requests a credit card and other billing details. The user agent could use this information to suggest a credit card that it knows has sufficient balance and that supports the relevant currency.<form method=post action="step2.cgi"> <input type=hidden autocomplete=transaction-currency value="CHF"> <input type=hidden autocomplete=transaction-amount value="15.00"> <p><label>Credit card number: <input type=text inputmode=numeric autocomplete=cc-number></label> <p><label>Expiry Date: <input type=month autocomplete=cc-exp></label> <p><input type=submit value="Continue..."> </form>
The autofill field keywords relate to each other as described in the table below. Each field name
listed on a row of this table corresponds to the meaning given in the cell for that row in the
column labeled "Meaning". Some fields correspond to subparts of other fields; for example, a
credit card expiry date can be expressed as one field giving both the month and year of expiry
("cc-exp
"), or as two fields, one giving the
month ("cc-exp-month
") and one the year
("cc-exp-year
"). In such cases, the names of
the broader fields cover multiple rows, in which the narrower fields are defined.
Generally, authors are encouraged to use the broader fields rather than the narrower fields, as the narrower fields tend to expose Western biases. For example, while it is common in some Western cultures to have a given name and a family name, in that order (and thus often referred to as a first name and a surname), many cultures put the family name first and the given name second, and many others simply have one name (a mononym). Having a single field is therefore more flexible.
Some fields are only appropriate for certain form controls. An autofill field name is inappropriate for a control if the control does not belong to the group listed for that autofill field in the fifth column of the first row describing that autofill field in the table below. What controls fall into each group is described below the table.
Field name | Meaning | Canonical Format | Canonical Format Example | Control group | |||
---|---|---|---|---|---|---|---|
"name "
| Full name | Free-form text, no newlines | Sir Timothy John Berners-Lee, OM, KBE, FRS, FREng, FRSA | Text | |||
"honorific-prefix "
| Prefix or title (e.g., "Mr.", "Ms.", "Dr.", "Mlle") | Free-form text, no newlines | Sir | Text | |||
"given-name "
| Given name (in some Western cultures, also known as the first name) | Free-form text, no newlines | Timothy | Text | |||
"additional-name "
| Additional names (in some Western cultures, also known as middle names, forenames other than the first name) | Free-form text, no newlines | John | Text | |||
"family-name "
| Family name (in some Western cultures, also known as the last name or surname) | Free-form text, no newlines | Berners-Lee | Text | |||
"honorific-suffix "
| Suffix (e.g., "Jr.", "B.Sc.", "MBASW", "II") | Free-form text, no newlines | OM, KBE, FRS, FREng, FRSA | Text | |||
"nickname "
| Nickname, screen name, handle: a typically short name used instead of the full name | Free-form text, no newlines | Tim | Text | |||
"organization-title "
| Job title (e.g., "Software Engineer", "Senior Vice President", "Deputy Managing Director") | Free-form text, no newlines | Professor | Text | |||
"username "
| A username | Free-form text, no newlines | timbl | Text | |||
"new-password "
| A new password (e.g., when creating an account or changing a password) | Free-form text, no newlines | GUMFXbadyrS3 | Password | |||
"current-password "
| The current password for the account identified by the username field (e.g., when logging in)
| Free-form text, no newlines | qwerty | Password | |||
"organization "
| Company name corresponding to the person, address, or contact information in the other fields associated with this field | Free-form text, no newlines | World Wide Web Consortium | Text | |||
"street-address "
| Street address (multiple lines, newlines preserved) | Free-form text | 32 Vassar Street MIT Room 32-G524 | Multiline | |||
"address-line1 "
| Street address (one line per field) | Free-form text, no newlines | 32 Vassar Street | Text | |||
"address-line2 "
| Free-form text, no newlines | MIT Room 32-G524 | Text | ||||
"address-line3 "
| Free-form text, no newlines | Text | |||||
"address-level4 "
| The most fine-grained administrative level, in addresses with four administrative levels | Free-form text, no newlines | Text | ||||
"address-level3 "
| The third administrative level, in addresses with three or more administrative levels | Free-form text, no newlines | Text | ||||
"address-level2 "
| The second administrative level, in addresses with two or more administrative levels; in the countries with two administrative levels, this would typically be the city, town, village, or other locality within which the relevant street address is found | Free-form text, no newlines | Cambridge | Text | |||
"address-level1 "
| The broadest administrative level in the address, i.e., the province within which the locality is found; for example, in the US, this would be the state; in Switzerland it would be the canton; in the UK, the post town | Free-form text, no newlines | MA | Text | |||
"country "
| Country code | Valid ISO 3166-1-alpha-2 country code [ISO3166] | US | Text | |||
"country-name "
| Country name | Free-form text, no newlines; derived from country in some cases
| US | Text | |||
"postal-code "
| Postal code, post code, ZIP code, CEDEX code (if CEDEX, append "CEDEX", and the dissement, if relevant, to the address-level2 field)
| Free-form text, no newlines | 02139 | Text | |||
"cc-name "
| Full name as given on the payment instrument | Free-form text, no newlines | Tim Berners-Lee | Text | |||
"cc-given-name "
| Given name as given on the payment instrument (in some Western cultures, also known as the first name) | Free-form text, no newlines | Tim | Text | |||
"cc-additional-name "
| Additional names given on the payment instrument (in some Western cultures, also known as middle names, forenames other than the first name) | Free-form text, no newlines | Text | ||||
"cc-family-name "
| Family name given on the payment instrument (in some Western cultures, also known as the last name or surname) | Free-form text, no newlines | Berners-Lee | Text | |||
"cc-number "
| Code identifying the payment instrument (e.g., the credit card number) | ASCII digits | 4114360123456785 | Text | |||
"cc-exp "
| Expiration date of the payment instrument | Valid month string | 2014-12 | Month | |||
"cc-exp-month "
| Month component of the expiration date of the payment instrument | valid integer in the range 1..12 | 12 | Numeric | |||
"cc-exp-year "
| Year component of the expiration date of the payment instrument | valid integer greater than zero | 2014 | Numeric | |||
"cc-csc "
| Security code for the payment instrument (also known as the card security code (CSC), card validation code (CVC), card verification value (CVV), signature panel code (SPC), credit card ID (CCID), etc) | ASCII digits | 419 | Text | |||
"cc-type "
| Type of payment instrument | Free-form text, no newlines | Visa | Text | |||
"transaction-currency "
| The currency that the user would prefer the transaction to use | ISO 4217 currency code [ISO4217] | GBP | Text | |||
"transaction-amount "
| The amount that the user would like for the transaction (e.g., when entering a bid or sale price) | Valid floating-point number | 401.00 | Numeric | |||
"language "
| Preferred language | Valid BCP 47 language tag [BCP47] | en | Text | |||
"bday "
| Birthday | Valid date string | 1955-06-08 | Date | |||
"bday-day "
| Day component of birthday | valid integer in the range 1..31 | 8 | Numeric | |||
"bday-month "
| Month component of birthday | valid integer in the range 1..12 | 6 | Numeric | |||
"bday-year "
| Year component of birthday | valid integer greater than zero | 1955 | Numeric | |||
"sex "
| Gender identity (e.g., Female, Fa’afafine) | Free-form text, no newlines | Male | Text | |||
"url "
| Home page or other Web page corresponding to the company, person, address, or contact information in the other fields associated with this field | Valid URL | https://www.w3.org/People/Berners-Lee/ | URL | |||
"photo "
| Photograph, icon, or other image corresponding to the company, person, address, or contact information in the other fields associated with this field | Valid URL | https://www.w3.org/Press/Stock/Berners-Lee/2001-europaeum-eighth.jpg | URL | |||
"tel "
| Full telephone number, including country code | ASCII digits and U+0020 SPACE characters, prefixed by a U+002B PLUS SIGN character (+) | +1 617 253 5702 | Tel | |||
"tel-country-code "
| Country code component of the telephone number | ASCII digits prefixed by a U+002B PLUS SIGN character (+) | +1 | Text | |||
"tel-national "
| Telephone number without the county code component, with a country-internal prefix applied if applicable | ASCII digits and U+0020 SPACE characters | 617 253 5702 | Text | |||
"tel-area-code "
| Area code component of the telephone number, with a country-internal prefix applied if applicable | ASCII digits | 617 | Text | |||
"tel-local "
| Telephone number without the country code and area code components | ASCII digits | 2535702 | Text | |||
"tel-local-prefix "
| First part of the component of the telephone number that follows the area code, when that component is split into two components | ASCII digits | 253 | Text | |||
"tel-local-suffix "
| Second part of the component of the telephone number that follows the area code, when that component is split into two components | ASCII digits | 5702 | Text | |||
"tel-extension "
| Telephone number internal extension code | ASCII digits | 1000 | Text | |||
"email "
| E-mail address | Valid e-mail address | timbl@w3.org | ||||
"impp "
| URL representing an instant messaging protocol endpoint (for example, "aim:goim?screenname=example " or "xmpp:fred@example.net ")
| Valid URL | irc://example.org/timbl,isuser | URL |
The groups correspond to controls as follows:
- Text
input
elements with atype
attribute in the Hidden stateinput
elements with atype
attribute in the Text stateinput
elements with atype
attribute in the Search statetextarea
elementsselect
elements- Multiline
input
elements with atype
attribute in the Hidden statetextarea
elementsselect
elements- Password
input
elements with atype
attribute in the Hidden stateinput
elements with atype
attribute in the Text stateinput
elements with atype
attribute in the Search stateinput
elements with atype
attribute in the Password statetextarea
elementsselect
elements- URL
input
elements with atype
attribute in the Hidden stateinput
elements with atype
attribute in the Text stateinput
elements with atype
attribute in the Search stateinput
elements with atype
attribute in the URL statetextarea
elementsselect
elementsinput
elements with atype
attribute in the Hidden stateinput
elements with atype
attribute in the Text stateinput
elements with atype
attribute in the Search stateinput
elements with atype
attribute in the E-mail statetextarea
elementsselect
elements- Tel
input
elements with atype
attribute in the Hidden stateinput
elements with atype
attribute in the Text stateinput
elements with atype
attribute in the Search stateinput
elements with atype
attribute in the Telephone statetextarea
elementsselect
elements- Numeric
input
elements with atype
attribute in the Hidden stateinput
elements with atype
attribute in the Text stateinput
elements with atype
attribute in the Search stateinput
elements with atype
attribute in the Number statetextarea
elementsselect
elements- Month
input
elements with atype
attribute in the Hidden stateinput
elements with atype
attribute in the Text stateinput
elements with atype
attribute in the Search stateinput
elements with atype
attribute in the Month statetextarea
elementsselect
elements- Date
input
elements with atype
attribute in the Hidden stateinput
elements with atype
attribute in the Text stateinput
elements with atype
attribute in the Search stateinput
elements with atype
attribute in the Date statetextarea
elementsselect
elements
Address levels: The "address-level1
" – "address-level4
" fields are used to describe
the locality of the street address. Different locales have different numbers of levels. For
example, the US uses two levels (state and town), the UK uses one or two depending on the address
(the post town, and in some cases the locality), and China can use three (province, city,
district). The "address-level1
" field
represents the widest administrative division. Different locales order the fields in different
ways; for example, in the US the town (level 2) precedes the state (level 1); while in Japan the
prefecture (level 1) precedes the city (level 2) which precedes the district (level 3). Authors
are encouraged to provide forms that are presented in a way that matches the country’s conventions
(hiding, showing, and rearranging fields accordingly as the user changes the country).
4.10.19.8.2. Processing model
Each input
element to which the autocomplete
attribute applies, each select
element, and each textarea
element, has an autofill hint set, an autofill scope, an autofill field name, and
an IDL-exposed autofill value.
The autofill field name specifies the specific kind of data expected in the field,
e.g., "street-address
" or "cc-exp
".
The autofill hint set identifies what address or contact information type the user
agent is to look at, e.g., "shipping
fax
" or "billing
".
The autofill scope identifies the group of fields that are to be filled with the
information from the same source, and consists of the autofill hint set with, if
applicable, the "section-*
" prefix, e.g., "billing
", "section-parent shipping
", or "section-child
shipping home
".
These values are defined as the result of running the following algorithm:
- If the element has no
autocomplete
attribute, then jump to the step labeled default. - Let tokens be the result of splitting the attribute’s value on spaces.
- If tokens is empty, then jump to the step labeled default.
- Let index be the index of the last token in tokens.
-
If the indexth token in tokens is not an ASCII case-insensitive match for one of the tokens given in the first column of the following table, or if the number of tokens in tokens is greater than the maximum number given in the cell in the second column of that token’s row, then jump to the step labeled default. Otherwise, let field be the string given in the cell of the first column of the matching row, and let category be the value of the cell in the third column of that same row.
Token Maximum number of tokens Category " off
"1 Off " on
"1 Automatic " name
"3 Normal " honorific-prefix
"3 Normal " given-name
"3 Normal " additional-name
"3 Normal " family-name
"3 Normal " honorific-suffix
"3 Normal " nickname
"3 Normal " organization-title
"3 Normal " username
"3 Normal " new-password
"3 Normal " current-password
"3 Normal " organization
"3 Normal " street-address
"3 Normal " address-line1
"3 Normal " address-line2
"3 Normal " address-line3
"3 Normal " address-level4
"3 Normal " address-level3
"3 Normal " address-level2
"3 Normal " address-level1
"3 Normal " country
"3 Normal " country-name
"3 Normal " postal-code
"3 Normal " cc-name
"3 Normal " cc-given-name
"3 Normal " cc-additional-name
"3 Normal " cc-family-name
"3 Normal " cc-number
"3 Normal " cc-exp
"3 Normal " cc-exp-month
"3 Normal " cc-exp-year
"3 Normal " cc-csc
"3 Normal " cc-type
"3 Normal " transaction-currency
"3 Normal " transaction-amount
"3 Normal " language
"3 Normal " bday
"3 Normal " bday-day
"3 Normal " bday-month
"3 Normal " bday-year
"3 Normal " sex
"3 Normal " url
"3 Normal " photo
"3 Normal " tel
"4 Contact " tel-country-code
"4 Contact " tel-national
"4 Contact " tel-area-code
"4 Contact " tel-local
"4 Contact " tel-local-prefix
"4 Contact " tel-local-suffix
"4 Contact " tel-extension
"4 Contact " email
"4 Contact " impp
"4 Contact - If category is Off or Automatic but the element’s
autocomplete
attribute is wearing the autofill anchor mantle, then jump to the step labeled default. - If category is Off, let the element’s autofill field name be the string "
off
", let its autofill hint set be empty, and let its IDL-exposed autofill value be the string "off
". Then, abort these steps. - If category is Automatic, let the element’s autofill field
name be the string "
on
", let its autofill hint set be empty, and let its IDL-exposed autofill value be the string "on
". Then, abort these steps. - Let scope tokens be an empty list.
- Let hint tokens be an empty set.
- Let IDL value have the same value as field.
- If the indexth token in tokens is the first entry, then skip to the step labeled done.
- Decrement index by one.
-
If category is Contact and the indexth token in tokens is an ASCII case-insensitive match for one of the strings in the following list, then run the substeps that follow:
- "
home
" - "
work
" - "
mobile
" - "
fax
" - "
pager
"
The substeps are:
- Let contact be the matching string from the list above.
- Insert contact at the start of scope tokens.
- Add contact to hint tokens.
- Let IDL value be the concatenation of contact, a U+0020 SPACE character, and the previous value of IDL value (which at this point will always be field).
- If the indexth entry in tokens is the first entry, then skip to the step labeled done.
- Decrement index by one.
- "
-
If the indexth token in tokens is an ASCII case-insensitive match for one of the strings in the following list, then run the substeps that follow:
- "
shipping
" - "
billing
"
The substeps are:
- Let mode be the matching string from the list above.
- Insert mode at the start of scope tokens.
- Add mode to hint tokens.
- Let IDL value be the concatenation of mode, a U+0020 SPACE character, and the previous value of IDL value (which at this point will either be field or the concatenation of contact, a space, and field).
- If the indexth entry in tokens is the first entry, then skip to the step labeled done.
- Decrement index by one.
- "
- If the indexth entry in tokens is not the first entry, then jump to the step labeled default.
- If the first eight characters of the indexth token in tokens are not
an ASCII case-insensitive match for the string "
section-
", then jump to the step labeled default. - Let section be the indexth token in tokens, converted to ASCII lowercase.
- Insert section at the start of scope tokens.
- Let IDL value be the concatenation of section, a U+0020 SPACE character, and the previous value of IDL value.
- Done: Let the element’s autofill hint set be hint tokens.
- Let the element’s autofill scope be scope tokens.
- Let the element’s autofill field name be field.
- Let the element’s IDL-exposed autofill value be IDL value.
- Abort these steps.
- Default: Let the element’s IDL-exposed autofill value be the empty string, and its autofill hint set and autofill scope be empty.
- If the element’s
autocomplete
attribute is wearing the autofill anchor mantle, then let the element’s autofill field name be the empty string and abort these steps. - Let form be the element’s form owner, if any, or null otherwise.
-
If form is not null and form’s
autocomplete
attribute is in the off state, then let the element’s autofill field name be "off
".Otherwise, let the element’s autofill field name be "
on
".
For the purposes of autofill, a control’s data depends on the kind of control:
- An
input
element with itstype
attribute in the E-mail state and with themultiple
attribute specified - The element’s values.
- Any other
input
element- A
textarea
element - A
- The element’s value.
- A
select
element with itsmultiple
attribute specified - The
option
elements in theselect
element’s list of options that have their selectedness set to true. - Any other
select
element - The
option
element in theselect
element’s list of options that has its selectedness set to true.
How to process the autofill hint set, autofill scope, and autofill field name depends on the mantle that the autocomplete
attribute is wearing.
- When wearing the autofill expectation mantle...
-
When an element’s autofill field name is "
off
", the user agent should not remember the control’s data, and should not offer past values to the user.In addition, when an element’s autofill field name is "
off
", values are reset when traversing the history.Banks frequently do not want user agents to prefill login information:<p><label>Account: <input type="text" name="ac" autocomplete="off"></label></p> <p><label>PIN: <input type="password" name="pin" autocomplete="off"></label></p>
When an element’s autofill field name is not "
off
", the user agent may store the control’s data, and may offer previously stored values to the user.For example, suppose a user visits a page with this control:<select name="country"> <option>Afghanistan <option>Albania <option>Algeria <option>Andorra <option>Angola <option>Antigua and Barbuda <option>Argentina <option>Armenia <!-- ... --> <option>Yemen <option>Zambia <option>Zimbabwe </select>
This might render as follows:
Suppose that on the first visit to this page, the user selects "Zambia". On the second visit, the user agent could duplicate the entry for Zambia at the top of the list, so that the interface instead looks like this:
When the autofill field name is "
on
", the user agent should attempt to use heuristics to determine the most appropriate values to offer the user, e.g., based on the element’sname
value, the position of the element in the document’s DOM, what other fields exist in the form, and so forth.When the autofill field name is one of the names of the autofill fields described above, the user agent should provide suggestions that match the meaning of the field name as given in the table earlier in this section. The autofill hint set should be used to select amongst multiple possible suggestions.
For example, if a user once entered one address into fields that used the "
shipping
" keyword, and another address into fields that used the "billing
" keyword, then in subsequent forms only the first address would be suggested for form controls whose autofill hint set contains the keyword "shipping
". Both addresses might be suggested, however, for address-related form controls whose autofill hint set does not contain either keyword. - When wearing the autofill anchor mantle...
-
When the autofill field name is not the empty string, then the user agent must act as if the user had specified the control’s data for the given autofill hint set, autofill scope, and autofill field name combination.
When the user agent autofills form controls, elements
with the same form owner and the same autofill scope must use data
relating to the same person, address, payment instrument, and contact details. When a user agent autofills "country
" and "country-name
" fields with the same form
owner and autofill scope, and the user agent has a value for the country
" field(s), then the "country-name
" field(s) must be filled using a
human-readable name for the same country. When a user agent fills in multiple fields at
once, all fields with the same autofill field name, form owner and autofill scope must be filled with the same value.
Suppose a user agent knows of two phone numbers, +1 555 123 1234 and +1 555 666 7777. It would
not be conforming for the user agent to fill a field with autocomplete="shipping tel-local-prefix"
with the value "123" and another field in
the same form with autocomplete="shipping tel-local-suffix"
with the value "7777".
The only valid prefilled values given the aforementioned information would be "123" and "1234",
or "666" and "7777", respectively.
Similarly, if a form for some reason contained both a "cc-exp
" field and a
"cc-exp-month
" field, and the user agent prefilled the form, then the month
component of the former would have to match the latter.
<form> <input type=hidden autocomplete="nickname" value="TreePlate"> <input type=text autocomplete="nickname"> </form>
The only value that a conforming user agent could suggest in the text field is
"TreePlate", the value given by the hidden input
element.
The "section-*
" tokens in the autofill scope are opaque;
user agents must not attempt to derive meaning from the precise values of these tokens.
For example, it would not be conforming if the user agent decided that it
should offer the address it knows to be the user’s daughter’s address for "section-child
" and the addresses it knows to be the user’s spouses' addresses for
"section-spouse
".
The autocompletion mechanism must be implemented by the user agent acting as if the user had modified the control’s data, and must be done at a time where the element is mutable (e.g., just after the element has been inserted into the document, or when the user agent stops parsing). User agents must only prefill controls using values that the user could have entered.
For example, if a select
element only has option
elements with values "Steve" and "Rebecca", "Jay", and "Bob", and has an autofill field
name "given-name
", but the user
agent’s only idea for what to prefill the field with is "Evan", then the user agent cannot prefill
the field. It would not be conforming to somehow set the select
element to the value
"Evan", since the user could not have done so themselves.
A user agent prefilling a form control’s value must not cause that control to suffer from a type mismatch, suffer from being too long, suffer from being too short, suffer from an underflow, suffer from an overflow, suffer from a step mismatch, or suffer from a pattern mismatch. Where possible given the control’s constraints, user agents must use the format given as canonical in the aforementioned table. Where it’s not possible for the canonical format to be used, user agents should use heuristics to attempt to convert values so that they can be used.
<input name=middle-initial maxlength=1 autocomplete="additional-name">
...then the user agent could convert "Ines" to "I" and prefill it that way.
<input name=b type=month autocomplete="bday"> | 2012-07 | The day is dropped since the Month state only accepts a month/year combination. |
<select name=c autocomplete="bday"> <option>Jan <option>Feb ... <option>Jul <option>Aug ... </select> | July | The user agent picks the month from the listed options, either by noticing there are twelve options and picking the 7th, or by recognizing that one of the strings (three characters "Jul" followed by a newline and a space) is a close match for the name of the month (July) in one of the user agent’s supported languages, or through some other similar mechanism. |
<input name=a type=number min=1 max=12 autocomplete="bday-month"> | 7 | User agent converts "July" to a month number in the range 1..12, like the field. |
<input name=a type=number min=0 max=11 autocomplete="bday-month"> | 6 | User agent converts "July" to a month number in the range 0..11, like the field. |
<input name=a type=number min=1 max=11 autocomplete="bday-month"> | User agent doesn’t fill in the field, since it can’t make a good guess as to what the form expects. |
A user agent may allow the user to override an element’s autofill field name, e.g.,
to change it from "off
" to "on
" to allow values to be remembered and prefilled despite
the page author’s objections, or to always "off
",
never remembering values.
More specifically, user agents may in particular consider replacing the autofill field
name of form controls that match the description given in the first column of the following
table, when their autofill field name is either "on
" or "off
", with the value given in the second cell of that
row. If this table is used, the replacements must be done in tree order, since all
but the first row references the autofill field name of earlier elements. When the
descriptions below refer to form controls being preceded or followed by others, they mean in the
list of listed elements that share the same form owner.
Form control | New autofill field name |
---|---|
an |
" |
an |
" |
an |
" |
an |
" |
The autocomplete
IDL attribute must reflect the content attribute of the same name.
4.10.20. APIs for text field selections
The input
and textarea
elements define the following members in their
DOM interfaces for handling their selection: select()
, selectionStart
, selectionEnd
, selectionDirection
, setRangeText(replacement)
, setSelectionRange(start, end)
The setRangeText()
method uses the following enumeration:
enum SelectionMode {
"select",
"start",
"end",
"preserve" // default
};
These methods and attributes expose and control the selection of input
and textarea
text fields.
- element .
select()
-
Selects everything in the text field.
- element .
selectionStart
[ = value ] -
Returns the offset to the start of the selection.
Can be set, to change the start of the selection.
- element .
selectionEnd
[ = value ] -
Returns the offset to the end of the selection.
Can be set, to change the end of the selection.
- element .
selectionDirection
[ = value ] -
Returns the current direction of the selection.
Can be set, to change the direction of the selection.
The possible values are "
forward
", "backward
", and "none
". - element . setSelectionRange(start, end [, direction] )
-
Changes the selection to cover the given substring in the given direction. If the direction is omitted, it will be reset to be the platform default (none or forward).
- element . setRangeText(replacement [, start, end [, selectionMode ] ] )
-
Replaces a range of text with the new text. If the start and end arguments are not provided, the range is assumed to be the selection.
The final argument determines how the selection should be set after the text has been replaced. The possible values are:
-
"
select
" -
Selects the newly inserted text.
-
"
start
" -
Moves the selection to just before the inserted text.
-
"
end
" -
Moves the selection to just after the selected text.
-
"
preserve
" -
Attempts to preserve the selection. This is the default.
-
For input
elements, calling these methods while they don’t apply, and getting or setting these attributes while they don’t apply, must throw an InvalidStateError
exception. Otherwise, they
must act as described below.
For input
elements, these methods and attributes must operate on the element’s value. For textarea
elements, these methods and
attributes must operate on the element’s raw value.
Where possible, user interface features for changing the text selection in input
and textarea
elements must be implemented in terms of the DOM API described in this
section, so that, e.g., all the same events fire.
The selections of input
and textarea
elements have a direction, which is either forward, backward, or none. This direction
is set when the user manipulates the selection. The exact meaning of the selection direction
depends on the platform.
On Windows, the direction indicates the position of the caret relative to the selection: a forward selection has the caret at the end of the selection and a backward selection has the caret at the start of the selection. Windows has no none direction. On Mac, the direction indicates which end of the selection is affected when the user adjusts the size of the selection using the arrow keys with the Shift modifier: the forward direction means the end of the selection is modified, and the backwards direction means the start of the selection is modified. The none direction is the default on Mac, it indicates that no particular direction has yet been selected. The user sets the direction implicitly when first adjusting the selection, based on which directional arrow key was used.
The select()
method must cause the
contents of the text field to be fully selected, with the selection direction being none, if the
platform support selections with the direction none, or otherwise forward. The user
agent must then queue a task to fire a simple event that bubbles named select
at the element, using the user interaction task
source as the task source.
In the case of input
elements, if the control has no text field, then the method
must do nothing.
For instance, in a user agent where <input type=color>
is rendered as a color well with a
picker, as opposed to a text field accepting a hexadecimal color code, there would be no text
field, and thus nothing to select, and thus calls to the method are ignored.
The selectionStart
attribute
must, on getting, return the offset (in logical order) to the character that immediately follows
the start of the selection. If there is no selection, then it must return the offset (in logical
order) to the character that immediately follows the text entry cursor.
On setting, it must act as if the setSelectionRange()
method had been called,
with the new value as the first argument; the current value of the selectionEnd
attribute as the second argument,
unless the current value of the selectionEnd
is less than the new value, in which case the second argument must also be the new value; and the
current value of the selectionDirection
as the third argument.
The selectionEnd
attribute
must, on getting, return the offset (in logical order) to the character that immediately follows
the end of the selection. If there is no selection, then it must return the offset (in logical
order) to the character that immediately follows the text entry cursor.
On setting, it must act as if the setSelectionRange()
method had been called,
with the current value of the selectionStart
attribute as the first argument,
the new value as the second argument, and the current value of the selectionDirection
as the third argument.
The selectionDirection
attribute must, on getting, return the string corresponding to the current selection direction: if
the direction is forward, "forward
"; if the direction is backward, "backward
"; and otherwise, "none
".
On setting, it must act as if the setSelectionRange()
method had been called,
with the current value of the selectionStart
IDL attribute as the first argument,
the current value of the selectionEnd
IDL
attribute as the second argument, and the new value as the third argument.
The setSelectionRange(start, end, direction)
method
must set the selection of the text field to the sequence of characters starting with the character
at the startth position (in logical order) and ending with the character at
the (end-1)th position. Arguments greater than the
length of the value of the text field must be treated as pointing at the end of the text field. If end is less than or equal to start then the start of the
selection and the end of the selection must both be placed immediately before the character with
offset end. In user agents where there is no concept of an empty selection, this must
set the cursor to be just before the character with offset end. The direction
of the selection must be set to backward if direction is a case-sensitive match for the string "backward
", forward if direction is a case-sensitive match for the string "forward
" or if the platform does not support selections with the direction none, and none otherwise (including if the argument is omitted). The user agent must
then queue a task to fire a simple event that bubbles named select
at the element, using the user interaction task
source as the task source.
The setRangeText(replacement, start, end, selectMode)
method must run the following steps:
-
If the method has only one argument, then let start and end have the values of the
selectionStart
IDL attribute and theselectionEnd
IDL attribute respectively.Otherwise, let start, end have the values of the second and third arguments respectively.
- If start is greater than end, then throw an
IndexSizeError
exception and abort these steps. - If start is greater than the length of the value of the text field, then set it to the length of the value of the text field.
- If end is greater than the length of the value of the text field, then set it to the length of the value of the text field.
- Let selection start be the current value of the
selectionStart
IDL attribute. - Let selection end be the current value of the
selectionEnd
IDL attribute. - If start is less than end, delete the sequence of characters starting with the character at the startth position (in logical order) and ending with the character at the (end-1)th position.
- Insert the value of the first argument into the text of the value of the text field, immediately before the startth character.
- Let new length be the length of the value of the first argument.
- Let new end be the sum of start and new length.
-
Run the appropriate set of substeps from the following list:
- If the fourth argument’s value is "
select
" -
Let selection start be start.
Let selection end be new end.
- If the fourth argument’s value is "
start
" -
Let selection start and selection end be start.
- If the fourth argument’s value is "
end
" -
Let selection start and selection end be new end.
- If the fourth argument’s value is "
preserve
" (the default) -
- Let old length be end minus start.
- Let delta be new length minus old length.
-
If selection start is greater than end, then increment it by delta. (If delta is negative, i.e., the new text is shorter than the old text, then this will decrease the value of selection start.)
Otherwise: if selection start is greater than start, then set it to start. (This snaps the start of the selection to the start of the new text if it was in the middle of the text that it replaced.)
-
If selection end is greater than end, then increment it by delta in the same way.
Otherwise: if selection end is greater than start, then set it to new end. (This snaps the end of the selection to the end of the new text if it was in the middle of the text that it replaced.)
- If the fourth argument’s value is "
-
Set the selection of the text field to the sequence of characters starting with the character at the selection startth position (in logical order) and ending with the character at the (selection end-1)th position. In user agents where there is no concept of an empty selection, this must set the cursor to be just before the character with offset end. The direction of the selection must be set to forward if the platform does not support selections with the direction none, and none otherwise.
- Queue a task to fire a simple event that bubbles named
select
at the element, using the user interaction task source as the task source.
All elements to which this API applies have either a selection or a text entry cursor position at all times (even for elements that are not being rendered). User agents should follow platform conventions to determine their initial state.
Characters with no visible rendering, such as U+200D ZERO WIDTH JOINER, still count as characters. Thus, for instance, the selection can include just an invisible character, and the text insertion cursor can be placed to one side or another of such a character.
var selectionText = control.value.substring(control.selectionStart, control.selectionEnd);
var oldStart = control.selectionStart; var oldEnd = control.selectionEnd; var oldDirection = control.selectionDirection; var prefix = "https://"; control.value = prefix + control.value; control.setSelectionRange(oldStart + prefix.length, oldEnd + prefix.length, oldDirection);
4.10.21. Constraints
4.10.21.1. Definitions
A submittable element is a candidate for constraint validation except when a condition has barred the element from constraint validation. (For example, an element is barred from
constraint validation if it is an object
element.)
An element can have a custom validity error message defined. Initially, an element
must have its custom validity error message set to the empty string. When its value
is not the empty string, the element is suffering from a custom error. It can be set
using the setCustomValidity()
method. The user
agent should use the custom validity error message when alerting the user to the
problem with the control.
An element can be constrained in various ways. The following is the list of validity states that a form control can be in, making the control invalid for the purposes of constraint validation. (The definitions below are non-normative; other parts of this specification define more precisely when each state applies or does not.)
-
Suffering from being missing
-
When a control has no value but has a
required
attribute (input
required
,textarea
required
); or, in the case of an element in a radio button group, any of the other elements in the group has arequired
attribute; or, forselect
elements, none of theoption
elements have their selectedness set (select
required
). -
Suffering from a type mismatch
-
When a control that allows arbitrary user input has a value that is not in the correct syntax (E-mail, URL).
-
Suffering from a pattern mismatch
-
When a control has a value that doesn’t satisfy the
pattern
attribute. -
Suffering from being too long
-
When a control has a value that is too long for the form control
maxlength
attribute (input
maxlength
,textarea
maxlength
). -
Suffering from being too short
-
When a control has a value that is too short for the form control
minlength
attribute (input
minlength
,textarea
minlength
). -
Suffering from an underflow
-
When a control has a value that is not the empty string and is too low for the
min
attribute. -
Suffering from an overflow
-
When a control has a value that is not the empty string and is too high for the
max
attribute. -
Suffering from a step mismatch
-
When a control has a value that doesn’t fit the rules given by the
step
attribute. -
Suffering from bad input
-
When a control has incomplete input and the user agent does not think the user ought to be able to submit the form in its current state.
-
Suffering from a custom error
-
When a control’s custom validity error message (as set by the element’s
setCustomValidity()
method) is not the empty string.
An element can still suffer from these states even when the element is disabled; thus these states can be represented in the DOM even if validating the form during submission wouldn’t indicate a problem to the user.
An element satisfies its constraints if it is not suffering from any of the above validity states.
4.10.21.2. Constraint validation
When the user agent is required to statically validate the constraints of form
element form, it must run the following steps, which return
either a positive result (all the controls in the form are valid) or a negative result (there are invalid controls) along with a (possibly empty) list of elements that are
invalid and for which no script has claimed responsibility:
- Let controls be a list of all the submittable elements whose form owner is form, in tree order.
- Let invalid controls be an initially empty list of elements.
-
For each element field in controls, in tree order, run the following substeps:
- If field is not a candidate for constraint validation, then move on to the next element.
- Otherwise, if field satisfies its constraints, then move on to the next element.
- Otherwise, add field to invalid controls.
- If invalid controls is empty, then return a positive result and abort these steps.
- Let unhandled invalid controls be an initially empty list of elements.
-
For each element field in invalid controls, if any, in tree order, run the following substeps:
- Fire a simple event named
invalid
that is cancelable at field. - If the event was not canceled, then add field to unhandled invalid controls.
- Fire a simple event named
- Return a negative result with the list of elements in the unhandled invalid controls list.
If a user agent is to interactively validate the constraints of form
element form, then the user agent must run the following steps:
- Statically validate the constraints of form, and let unhandled invalid controls be the list of elements returned if the result was negative.
- If the result was positive, then return that result and abort these steps.
- Report the problems with the constraints of at least one of the elements given in unhandled invalid controls to the user. User agents may focus one of those elements in
the process, by running the focusing steps for that element, and may change the
scrolling position of the document, or perform some other action that brings the element to the
user’s attention. User agents may report more than one constraint violation. User agents may
coalesce related constraint violation reports if appropriate (e.g., if multiple radio buttons in a group are marked as required, only one error need be
reported). If one of the controls is not being rendered (e.g., it has the
hidden
attribute set) then user agents may report a script error. - Return a negative result.
4.10.21.3. The constraint validation API
- element .
willValidate
-
Returns true if the element will be validated when the form is submitted; false otherwise.
- element . {{HTMLInputElement/setCustomValidity(message)}}
-
Sets a custom error, so that the element would fail to validate. The given message is the message to be shown to the user when reporting the problem to the user.
If the argument is the empty string, clears the custom error.
- element .
validity
.valueMissing
-
Returns true if the element has no value but is a required field; false otherwise.
- element .
validity
.typeMismatch
-
Returns true if the element’s value is not in the correct syntax; false otherwise.
- element .
validity
.patternMismatch
-
Returns true if the element’s value doesn’t match the provided pattern; false otherwise.
- element .
validity
.tooLong
-
Returns true if the element’s value is longer than the provided maximum length; false otherwise.
- element .
validity
.tooShort
-
Returns true if the element’s value, if it is not the empty string, is shorter than the provided minimum length; false otherwise.
- element .
validity
.rangeUnderflow
-
Returns true if the element’s value is lower than the provided minimum; false otherwise.
- element .
validity
.rangeOverflow
-
Returns true if the element’s value is higher than the provided maximum; false otherwise.
- element .
validity
.stepMismatch
-
Returns true if the element’s value doesn’t fit the rules given by the
step
attribute; false otherwise. - element .
validity
.badInput
-
Returns true if the user has provided input in the user interface that the user agent is unable to convert to a value; false otherwise.
- element .
validity
.customError
-
Returns true if the element has a custom error; false otherwise.
- element .
validity
.valid
-
Returns true if the element’s value has no validity problems; false otherwise.
- valid = element .
checkValidity
() -
Returns true if the element’s value has no validity problems; false otherwise. Fires an
invalid
event at the element in the latter case. - valid = element .
reportValidity
() -
Returns true if the element’s value has no validity problems; otherwise, returns false, fires an
invalid
event at the element, and (if the event isn’t canceled) reports the problem to the user. - element .
validationMessage
-
Returns the error message that would be shown to the user if the element was to be checked for validity.
The willValidate
IDL attribute must return
true if an element is a candidate for constraint validation, and false otherwise
(i.e., false if any conditions are barring it from
constraint validation).
The setCustomValidity(message)
,
when invoked, must set the custom validity error message to the value of the given message argument.
setCustomValidity()
method to set an appropriate
message.
<label>Feeling: <input name=f type="text" oninput="check(this)"></label> <script> function check(input) { if (input.value == "good" || input.value == "fine" || input.value == "tired") { input.setCustomValidity('"' + input.value + '" is not a feeling.'); } else { // input is fine -- reset the error message input.setCustomValidity(''); } } </script>
The validity
IDL attribute must return a ValidityState
object that represents
the validity states of the element.
This object is live.
interface ValidityState { readonly attribute boolean valueMissing; readonly attribute boolean typeMismatch; readonly attribute boolean patternMismatch; readonly attribute boolean tooLong; readonly attribute boolean tooShort; readonly attribute boolean rangeUnderflow; readonly attribute boolean rangeOverflow; readonly attribute boolean stepMismatch; readonly attribute boolean badInput; readonly attribute boolean customError; readonly attribute boolean valid; };
A ValidityState
object has the following attributes. On getting, they must return
true if the corresponding condition given in the following list is true, and false otherwise.
-
valueMissing
, of type boolean, readonly -
The control is suffering from being missing.
-
typeMismatch
, of type boolean, readonly -
The control is suffering from a type mismatch.
-
patternMismatch
, of type boolean, readonly -
The control is suffering from a pattern mismatch.
-
tooLong
, of type boolean, readonly -
The control is suffering from being too long.
-
tooShort
, of type boolean, readonly -
The control is suffering from being too short.
-
rangeUnderflow
, of type boolean, readonly -
The control is suffering from an underflow.
-
rangeOverflow
, of type boolean, readonly -
The control is suffering from an overflow.
-
stepMismatch
, of type boolean, readonly -
The control is suffering from a step mismatch.
-
badInput
, of type boolean, readonly -
The control is suffering from bad input.
-
customError
, of type boolean, readonly -
The control is suffering from a custom error.
-
valid
, of type boolean, readonly -
None of the other conditions are true.
When the checkValidity()
method is
invoked, if the element is a candidate for constraint validation and does not satisfy its constraints, the user agent must fire a simple
event named invalid
that is cancelable (but in this case
has no default action) at the element and return false. Otherwise, it must only return true
without doing anything else.
When the reportValidity()
method is
invoked, if the element is a candidate for constraint validation and does not satisfy its constraints, the user agent must: fire a simple
event named invalid
that is cancelable at the element,
and if that event is not canceled, report the problems with the constraints of that element to the
user; then, return false. Otherwise, it must only return true without doing anything else. When
reporting the problem with the constraints to the user, the user agent may run the focusing
steps for that element, and may change the scrolling position of the document, or perform
some other action that brings the element to the user’s attention. User agents may report more
than one constraint violation, if the element suffers from multiple problems at once. If the
element is not being rendered, then the user agent may, instead of notifying the
user, report a script error.
The validationMessage
attribute must
return the empty string if the element is not a candidate for constraint validation or if it is one but it satisfies its constraints; otherwise,
it must return a suitably localized message that the user agent would show the user if this were
the only form control with a validity constraint problem. If the user agent would not actually
show a textual message in such a situation (e.g., it would show a graphical cue instead), then the
attribute must return a suitably localized message that expresses (one or more of) the validity
constraint(s) that the control does not satisfy. If the element is a candidate for
constraint validation and is suffering from a custom error, then the custom validity error message should be present in the return value.
4.10.21.4. Security
Servers should not rely on client-side validation. Client-side validation can be intentionally bypassed by hostile users, and unintentionally bypassed by users of older user agents or automated tools that do not implement these features. The constraint validation features are only intended to improve the user experience, not to provide any kind of security mechanism.
4.10.22. Form submission
4.10.22.1. Introduction
This section is non-normative.
When a form is submitted, the data in the form is converted into the structure specified by the enctype, and then sent to the destination specified by the action
using the given method.
For example, take the following form:
<form action="/find.cgi" method=get> <input type=text name=t> <input type=search name=q> <input type=submit> </form>
If the user types in "cats" in the first field and "fur" in the second, and then hits the
submit button, then the user agent will load /find.cgi?t=cats&q=fur
.
On the other hand, consider this form:
<form action="/find.cgi" method=post enctype="multipart/form-data"> <input type=text name=t> <input type=search name=q> <input type=submit> </form>
Given the same user input, the result on submission is quite different: the user agent instead does an HTTP POST to the given URL, with as the entity body something like the following text:
------kYFrd4jNJEgCervEContent-Disposition: form-data; name="t" cats ------kYFrd4jNJEgCervE Content-Disposition: form-data; name="q" fur ------kYFrd4jNJEgCervE--
4.10.22.2. Implicit submission
A form
element’s default button is the first submit button in tree order whose form
owner is that form
element.
If the user agent supports letting the user submit a form implicitly (for example, on some platforms hitting the "enter" key while a text field is focused implicitly submits the form), then doing so for a form whose default button has a defined activation behavior must cause the user agent to run synthetic click activation steps on that default button.
Consequently, if the default button is disabled, the form is not submitted when such an implicit submission mechanism is used. (A button has no activation behavior when disabled.)
There are pages on the Web that are only usable if there is a way to implicitly submit forms, so user agents are strongly encouraged to support this.
If the form has
no submit button, then the implicit submission
mechanism must do nothing if the form has more than one field that blocks implicit
submission, and must submit the form
element from the form
element itself otherwise.
For the purpose of the previous paragraph, an element is a field that blocks implicit
submission of a form
element if it is an input
element whose form owner is that form
element and whose type
attribute is in one of the following states: Text, Search, URL, Telephone, E-mail, Password, Date, Month, Week, Time, Number
4.10.22.3. Form submission algorithm
When a form
element form is submitted from an element submitter (typically a button), optionally with a submitted from submit()
method flag set, the user agent must run the
following steps:
- Let form document be the form’s node document.
- If form document has no associated browsing context or its active sandboxing flag set has its sandboxed forms browsing context flag set, then abort these steps without doing anything.
- Let form browsing context be the browsing context of form document.
- If the submitted from
submit()
method flag is not set, and the submitter element’s no-validate state is false, then interactively validate the constraints of form and examine the result: if the result is negative (the constraint validation concluded that there were invalid fields and probably informed the user of this) then fire a simple event namedinvalid
at the form element and then abort these steps. - If the submitted from
submit()
method flag is not set, then fire a simple event that bubbles and is cancelable namedsubmit
, at form. If the event’s default action is prevented (i.e., if the event is canceled) then abort these steps. Otherwise, continue (effectively the default action is to perform the submission). - Let form data set be the result of constructing the form data set for form in the context of submitter.
- Let action be the submitter element’s action.
-
If action is the empty string, let action be the document’s address of the form document.
- Parse the URL action, relative to the submitter element’s node document. If this fails, abort these steps.
- Let action be the resulting URL string.
- Let action components be the resulting URL record.
- Let scheme be the scheme of the resulting URL record.
- Let enctype be the submitter element’s enctype.
- Let method be the submitter element’s method.
- Let target be the submitter element’s target.
- If the user indicated a specific browsing context to use when submitting the form, then let target browsing context be that browsing context. Otherwise, apply the rules for choosing a browsing context given a browsing context name using target as the name and form browsing context as the context in which the algorithm is executed, and let target browsing context be the resulting browsing context.
- If target browsing context was created in the previous step, or,
alternatively, if the form document has not yet completely
loaded and the submitted from
submit()
method flag is set, then let replace be true. Otherwise, let it be false. -
Otherwise, select the appropriate row in the table below based on the value of scheme as given by the first cell of each row. Then, select the appropriate cell on that row based on the value of method as given in the first cell of each column. Then, jump to the steps named in that cell and defined below the table.
GET POST http
Mutate action URL Submit as entity body https
Mutate action URL Submit as entity body ftp
Get action URL Get action URL javascript
Get action URL Get action URL data
Get action URL Post to data: mailto
Mail with headers Mail as body If scheme is not one of those listed in this table, then the behavior is not defined by this specification. User agents should, in the absence of another specification defining this, act in a manner analogous to that defined in this specification for similar schemes.
Each
form
element has a planned navigation, which is either null or a task; when theform
is first created, its planned navigation must be set to null. In the behaviors described below, when the user agent is required to plan to navigate to a particular resource destination, it must run the following steps:- If the
form
has a non-null planned navigation, remove it from its task queue. -
Let the
form
's planned navigation be a new task that consists of running the following steps:- Let the
form
's planned navigation be null. - Navigate target browsing context to destination. If replace is true, then target browsing context must be navigated with replacement enabled.
For the purposes of this task, target browsing context and replace are the variables that were set up when the overall form submission algorithm was run, with their values as they stood when this planned navigation was queued.
- Let the
-
Queue a task that is the
form
's new planned navigation.The task source for this task is the DOM manipulation task source.
The behaviors are as follows:
-
Mutate action URL
-
Let query be the result of encoding the form data set using the
application/x-www-form-urlencoded
encoding algorithm, interpreted as a US-ASCII string.Set parsed action’s query component to query.
Let destination be a new URL formed by applying the URL serializer algorithm to parsed action.
Plan to navigate to destination.
-
Submit as entity body
-
Let entity body be the result of encoding the form data set using the appropriate form encoding algorithm.
Let MIME type be determined as follows:
-
If enctype is
application/x-www-form-urlencoded
-
Let MIME type be "
application/x-www-form-urlencoded
". -
If enctype is
multipart/form-data
-
Let MIME type be the concatenation of the string "
multipart/form-data;
", a U+0020 SPACE character, the string "boundary=
", and themultipart/form-data
boundary string generated by themultipart/form-data
encoding algorithm. -
If enctype is
text/plain
-
Let MIME type be "
text/plain
".
Otherwise, plan to navigate to a new request whose URL is action, method is method, header list consists of
Content-Type
/MIME type, and body is entity body. -
-
Get action URL
-
Plan to navigate to action.
The form data set is discarded.
-
Post to data:
-
Let data be the result of encoding the form data set using the appropriate form encoding algorithm.
If action contains the string "
%%%%
" (four U+0025 PERCENT SIGN characters), then percent encode all bytes in data that, if interpreted as US-ASCII, are not characters in the URL default encode set, and then, treating the result as a US-ASCII string, UTF-8 percent encode all the U+0025 PERCENT SIGN characters in the resulting string and replace the first occurrence of "%%%%
" in action with the resulting doubly-escaped string. [URL]Otherwise, if action contains the string "
%%
" (two U+0025 PERCENT SIGN characters in a row, but not four), then UTF-8 percent encode all characters in data that, if interpreted as US-ASCII, are not characters in the URL default encode set, and then, treating the result as a US-ASCII string, replace the first occurrence of "%%
" in action with the resulting escaped string. [URL]Plan to navigate to the potentially modified action (which will be a
data:
URL). -
Mail with headers
-
Let headers be the resulting encoding the form data set using the
application/x-www-form-urlencoded
encoding algorithm, interpreted as a US-ASCII string.Replace occurrences of U+002B PLUS SIGN characters (+) in headers with the string "
%20
".Let destination consist of all the characters from the first character in action to the character immediately before the first U+003F QUESTION MARK character (?), if any, or the end of the string if there are none.
Append a single U+003F QUESTION MARK character (?) to destination.
Append headers to destination.
Plan to navigate to destination.
-
Mail as body
-
Let body be the resulting of encoding the form data set using the appropriate form encoding algorithm and then percent encoding all the bytes in the resulting byte string that, when interpreted as US-ASCII, are not characters in the URL default encode set. [URL]
Let destination have the same value as action.
If destination does not contain a U+003F QUESTION MARK character (?), append a single U+003F QUESTION MARK character (?) to destination. Otherwise, append a single U+0026 AMPERSAND character (&).
Append the string "
body=
" to destination.Append body, interpreted as a US-ASCII string, to destination.
Plan to navigate to destination.
The appropriate form encoding algorithm is determined as follows:
-
If enctype is
application/x-www-form-urlencoded
-
Use the
application/x-www-form-urlencoded
encoding algorithm. -
If enctype is
multipart/form-data
-
If enctype is
text/plain
-
Use the
text/plain
encoding algorithm.
- If the
4.10.22.4. Constructing the form data set
The algorithm to construct the form data set for a form form optionally in the context of a submitter submitter is as follows. If not specified otherwise, submitter is null.
- Let controls be a list of all the submittable elements whose form owner is form, in tree order.
- Let the form data set be a list of name-value-type tuples, initially empty.
-
Loop: For each element field in controls, in tree order, run the following substeps:
-
If any of the following conditions are met, then skip these substeps for this element:
- The field element has a
datalist
element ancestor. - The field element is disabled.
- The field element is a button but it is not submitter.
- The field element is an
input
element whosetype
attribute is in the Checkbox state and whose checkedness is false. - The field element is an
input
element whosetype
attribute is in the Radio Button state and whose checkedness is false. - The field element is not an
input
element whosetype
attribute is in the image button state, and either the field element does not have aname
attribute specified, or itsname
attribute’s value is the empty string. - The field element is an
object
element that is not using a plugin.
Otherwise, process field as follows:
- The field element has a
- Let type be the value of the
type
IDL attribute of field. -
If the field element is an
input
element whosetype
attribute is in the image button state, then run these further nested substeps:- If the field element has a
name
attribute specified and its value is not the empty string, let name be that value followed by a single U+002E FULL STOP character (.). Otherwise, let name be the empty string. - Let namex be the string consisting of the concatenation of name and a single U+0078 LATIN SMALL LETTER X character (x).
- Let namey be the string consisting of the concatenation of name and a single U+0079 LATIN SMALL LETTER Y character (y).
- The field element is submitter, and before this algorithm was invoked the user indicated a coordinate. Let x be the x-component of the coordinate selected by the user, and let y be the y-component of the coordinate selected by the user.
- Append an entry to the form data set with the name namex, the value x, and the type type.
- Append an entry to the form data set with the name namey and the value y, and the type type.
- Skip the remaining substeps for this element: if there are any more elements in controls, return to the top of the loop step, otherwise, jump to the end step below.
- If the field element has a
- Let name be the value of the field element’s
name
attribute. - If the field element is a
select
element, then for eachoption
element in theselect
element’s list of options whose selectedness is true and that is not disabled, append an entry to the form data set with the name as the name, the value of theoption
element as the value, and type as the type. -
Otherwise, if the field element is an
input
element whosetype
attribute is in the Checkbox state or the Radio Button state, then run these further nested substeps:- If the field element has a
value
attribute specified, then let value be the value of that attribute; otherwise, let value be the string "on
". - Append an entry to the form data set with name as the name, value as the value, and type as the type.
- If the field element has a
- Otherwise, if the field element is an
input
element whosetype
attribute is in the File Upload state, then for each file selected in theinput
element, append an entry to the form data set with the name as the name, the file (consisting of the name, the type, and the body) as the value, and type as the type. If there are no selected files, then append an entry to the form data set with the name as the name, the empty string as the value, andapplication/octet-stream
as the type. - Otherwise, if the field element is an
object
element: try to obtain a form submission value from the plugin, and if that is successful, append an entry to the form data set with name as the name, the returned form submission value as the value, and the string "object
" as the type. - Otherwise, append an entry to the form data set with name as the name, the value of the field element as the value, and type as the type.
-
If the element has a
dirname
attribute, and that attribute’s value is not the empty string, then run these substeps:- Let dirname be the value of the element’s
dirname
attribute. - Let dir be the string "
ltr
" if the directionality of the element is 'ltr', and "rtl
" otherwise (i.e., when the directionality of the element is 'rtl'). - Append an entry to the form data set with dirname as the name, dir as the value, and the string
"
direction
" as the type.
An element can only have a
dirname
attribute if it is atextarea
element or aninput
element whosetype
attribute is in either the Text state or the Search state. - Let dirname be the value of the element’s
-
-
End: For the name of each entry in the form data set, and for the value of each entry in the form data set whose type is not "
file
" or "textarea
", replace every occurrence of a U+000D CARRIAGE RETURN (CR) character not followed by a U+000A LINE FEED (LF) character, and every occurrence of a U+000A LINE FEED (LF) character not preceded by a U+000D CARRIAGE RETURN (CR) character, by a two-character string consisting of a U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pair.In the case of the value of
textarea
elements, this newline normalization is already performed during the conversion of the control’s raw value into the control’s value (which also performs any necessary line wrapping). In the case ofinput
elementstype
attributes in the File Upload state, the value is not normalized. - Return the form data set.
4.10.22.5. Selecting a form submission encoding
If the user agent is to pick an encoding for a form, it must run the following steps:
-
Let encoding be the document’s character encoding.
-
If the
form
element has anaccept-charset
attribute, set encoding to the return value of running these substeps:-
Let input be the value of the
form
element’saccept-charset
attribute. -
Let candidate encoding labels be the result of splitting input on spaces.
-
Let candidate encodings be an empty list of character encodings.
-
For each token in candidate encoding labels in turn (in the order in which they were found in input), get an encoding for the token and, if this does not result in failure, append the encoding to candidate encodings.
-
If candidate encodings is empty, return UTF-8.
-
Return the first encoding in candidate encodings.
-
-
Return the result of getting an output encoding from encoding.
4.10.22.6. URL-encoded form data
See the WHATWG URL specification for details on application/x-www-form-urlencoded
. [URL]
The application/x-www-form-urlencoded
encoding algorithm is as follows:
-
Let encoding be the result of picking an encoding for the form.
-
Let serialized be the result of running the
application/x-www-form-urlencoded
serializer given form data set and encoding. -
Return the result of encoding serialized.
4.10.22.7. Multipart form data
The multipart/form-data
encoding algorithm is as follows:
- Let result be the empty string.
-
If the algorithm was invoked with an explicit character encoding, let the selected character encoding be that encoding. (This algorithm is used by other specifications, which provide an explicit character encoding to avoid the dependency on the
form
element described in the next paragraph.)Otherwise, if the
form
element has anaccept-charset
attribute, let the selected character encoding be the result of picking an encoding for the form.Otherwise, if the
form
element has noaccept-charset
attribute, but the document’s character encoding is an ASCII-compatible encoding, then that is the selected character encoding.Otherwise, let the selected character encoding be UTF-8.
- Let charset be the name of the selected character encoding.
-
For each entry in the form data set, perform these substeps:
- If the entry’s name is "
_charset_
" and its type is "hidden
", replace its value with charset. - For each character in the entry’s name and value that cannot be expressed using the selected character encoding, replace the character by a string consisting of a U+0026 AMPERSAND character (&), a U+0023 NUMBER SIGN character (#), one or more ASCII digits representing the Unicode code point of the character in base ten, and finally a U+003B SEMICOLON character (;).
- If the entry’s name is "
-
Encode the (now mutated) form data set using the rules described by RFC 7578, Returning Values from Forms:
multipart/form-data
, and return the resulting byte stream. [RFC7578]Each entry in the form data set is a field, the name of the entry is the field name and the value of the entry is the field value.
The order of parts must be the same as the order of fields in the form data set. Multiple entries with the same name must be treated as distinct fields.
The parts of the generated
multipart/form-data
resource that correspond to non-file fields must not have aContent-Type
header specified. Their names and values must be encoded using the character encoding selected above.File names included in the generated
multipart/form-data
resource (as part of file fields) must use the character encoding selected above, though the precise name may be approximated if necessary (e.g., newlines could be removed from file names, quotes could be changed to "%22", and characters not expressible in the selected character encoding could be replaced by other characters).The boundary used by the user agent in generating the return value of this algorithm is the
multipart/form-data
boundary string. (This value is used to generate the MIME type of the form submission payload generated by this algorithm.)
For details on how to interpret multipart/form-data
payloads, see RFC 7578. [RFC7578]
4.10.22.8. Plain text form data
The text/plain
encoding algorithm is as follows:
- Let result be the empty string.
- Let encoding be the result of picking an encoding for the form.
- Let charset be the name of encoding.
- If the entry’s name is "
_charset_
" and its type is "hidden
", replace its value with charset. - If the entry’s type is "
file
", replace its value with the file’s name only. -
For each entry in the form data set, perform these substeps:
- Append the entry’s name to result.
- Append a single U+003D EQUALS SIGN character (=) to result.
- Append the entry’s value to result.
- Append a U+000D CARRIAGE RETURN (CR) U+000A LINE FEED (LF) character pair to result.
- Return the result of encoding result using encoding.
Payloads using the text/plain
format are intended to be human readable. They are
not reliably interpretable by computer, as the format is ambiguous (for example, there is no way
to distinguish a literal newline in a value from the newline at the end of the value).
4.10.23. Resetting a form
When a form
element form is reset, the user agent must fire a simple event named reset
, that bubbles and is cancelable, at form, and then, if that event is not canceled, must invoke the reset algorithm of each resettable element whose form owner is form.
When the reset algorithm is invoked by the reset()
method, the reset
event
fired by the reset algorithm must not be trusted.
Each resettable element defines its own reset algorithm. Changes made to form controls as part of
these algorithms do not count as changes caused by the user (and thus, e.g., do not cause input
events to fire).
4.11. Interactive elements
4.11.1. The details
element
- Categories:
- Flow content.
- Sectioning root.
- Interactive content.
- Palpable content.
- Sectioning root.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- One
summary
element followed by flow content. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
open
- Whether the details are visible - Allowed ARIA role attribute values:
- Any role that supports
aria-expanded
. - Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLDetailsElement : HTMLElement { attribute boolean open; };
The details
element represents a disclosure widget from which the
user can obtain additional information or controls.
The details
element is not appropriate for footnotes. Please see §4.13.5 Footnotes for details on how to mark up footnotes.
The first summary
element child of the element, if any, represents the summary or legend of the details. If there is no
child summary
element, the user agent should provide its own legend (e.g.,
"Details").
The rest of the element’s contents represents the additional information or controls.
The open
content attribute is a boolean
attribute. If present, it indicates that both the summary and the additional information is
to be shown to the user. If the attribute is absent, only the summary is to be shown.
When the element is created, if the attribute is absent, the additional information should be hidden; if the attribute is present, that information should be shown. Subsequently, if the attribute is removed, then the information should be hidden; if the attribute is added, the information should be shown.
The user agent should allow the user to request that the additional information be shown or
hidden. To honor a request for the details to be shown, the user agent must set the open
attribute on the element to the value open
. To honor a request for the information to be hidden, the user agent must
remove the open
attribute from the element.
Whenever the open
attribute is added to or removed from
a details
element, the user agent must queue a task that runs the
following steps, which are known as the details notification task steps, for this details
element:
-
If another task has been queued to run the details notification task steps for this
details
element, then abort these steps.When the
open
attribute is toggled several times in succession, these steps essentially get coalesced so that only one event is fired. - Fire a simple event named
toggle
at thedetails
element.
The task source for this task must be the DOM manipulation task source.
The open
IDL attribute must reflect the open
content attribute.
details
element being used to hide technical
details in a progress report.
<section class="progress window"> <h1>Copying "Really Achieving Your Childhood Dreams"</h1> <details> <summary>Copying... <progress max="375505392" value="97543282"></progress> 25%</summary> <dl> <dt>Transfer rate:</dt> <dd>452KB/s</dd> <dt>Local filename:</dt> <dd>/home/rpausch/raycd.m4v</dd> <dt>Remote filename:</dt> <dd>/var/www/lectures/raycd.m4v</dd> <dt>Duration:</dt> <dd>01:16:27</dd> <dt>Color profile:</dt> <dd>SD (6-1-6)</dd> <dt>Dimensions:</dt> <dd>320×240</dd> </dl> </details> </section>
details
element can be used to hide some controls by
default:
<details> <summary><label for=fn>Name & Extension:</label></summary> <p><input type=text id=fn name=fn value="Pillar Magazine.pdf"> <p><label><input type=checkbox name=ext checked> Hide extension</label> </details>
One could use this in conjunction with other details
in a list to allow the user
to collapse a set of fields down to a small set of headings, with the ability to open each
one.
In these examples, the summary really just summarizes what the controls can change, and not the actual values, which is less than ideal.
open
attribute is added and removed
automatically as the user interacts with the control, it can be used in CSS to style the element
differently based on its state. Here, a stylesheet is used to animate the color of the summary
when the element is opened or closed:
<style> details > summary { transition: color 1s; color: black; } details[open] > summary { color: red; } </style> <details> <summary>Automated Status: Operational</summary> <p>Velocity: 12m/s</p> <p>Direction: North</p> </details>
4.11.2. The summary
element
- Categories:
- None.
- Contexts in which this element can be used:
- As the first child of a
details
element. - Content model:
- Either: phrasing content.
- Or: one element of heading content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
button
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
- Uses
HTMLElement
.
The summary
element represents a summary, caption, or legend for the
rest of the contents of the summary
element’s parent details
element, if any.
4.11.3. The menu
element
- Categories:
- Flow content.
- Contexts in which this element can be used:
- Where flow content is expected.
- If the element’s
type
attribute is in the popup menu state: as the child of amenu
element whosetype
attribute is in the popup menu state. - If the element’s
- Content model:
- If the element’s
type
attribute is in the popup menu state: in any order, zero or moremenuitem
elements, zero or morehr
elements, zero or moremenu
elements whosetype
attributes are in the popup menu state, and zero or more script-supporting elements. - Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
type
- Type of menulabel
- User-visible label - Allowed ARIA role attribute values:
menu
(default - do not set),directory
,list
,listbox
,menubar
,tablist
,tabpanel
ortree
.- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLMenuElement : HTMLElement { attribute DOMString type; attribute DOMString label; };
The menu
element represents a group of commands.
The type
attribute is an enumerated
attribute indicating the kind of menu being declared. The attribute has 1 state. The
"context
" keyword maps to the popup menu state, in which the element is declaring a context menu. The attribute may also be
omitted. The missing value default is the popup menu state.
If a menu
element’s type
attribute is in the popup menu state, then the element represents the commands of a popup menu, and the user can only examine and interact with the commands if that
popup menu is activated through some other element via the contextmenu
attribute.
The label
attribute gives the label of the
menu. It is used by user agents to display nested menus in the UI: a context menu containing
another menu would use the nested menu’s label
attribute for
the submenu’s menu label. The label
attribute must only be
specified on menu
elements whose parent element is a menu
element whose type
attribute is in the popup
menu state.
A menu
is a currently relevant menu
element if it is the
child of a currently relevant menu
element, or if it is the designated pop-up menu of a button
element that is not inert, does not have a hidden
attribute, and is not
the descendant of an element with a hidden
attribute.
A menu construct consists of an ordered list of zero or more menu item constructs, which can be any of:
- Commands, which can be marked as default commands (
menuitem
) - Separators (
hr
) - Other menu constructs, each with an associated submenu label, which allows the list to be nested (
menu
)
To build and show a menu for a particular menu
element source and with a particular element subject as a subject, the user agent
must run the following steps:
- Let pop-up menu be the menu construct created by the build a menu construct algorithm when passed the source element.
-
Display pop-up menu to the user, and let the algorithm that invoked this one continue.
If the user selects a menu item construct that corresponds to an element that still represents a command when the user selects it, then the user agent must invoke that command’s Action. If the command’s Action is defined as firing a
click
event, either directly or via the run synthetic click activation steps algorithm, then therelatedTarget
attribute of thatclick
event must be initialized to subject.Pop-up menus must not, while being shown, reflect changes in the DOM. The menu is constructed from the DOM before being shown, and is then immutable.
To build a menu construct for an element source, the user agent must run the following steps, which return a menu construct:
- Let generated menu be an empty menu construct.
-
Run the menu item generator steps for the
menu
element using generated menu as the output.The menu item generator steps for a
menu
element using a specific menu construct output as output are as follows: For each child node of themenu
in tree order, run the appropriate steps from the following list:- If the child is a
menuitem
element that defines a command - Append the command to output, respecting the command’s facets. If the
menuitem
element has adefault
attribute, mark the command as being a default command. - If the child is an
hr
element - Append a separator to output.
- If the child is a
menu
element with nolabel
attribute - Append a separator to output, then run
the menu item generator steps for this child
menu
element, using output as the output, then append another separator to output. - If the child is a
menu
element with alabel
attribute - Let submenu be the result of running the build a menu construct steps for the child
menu
element. Then, append submenu to output, using the value of the childmenu
element’slabel
attribute as the submenu label. - Otherwise
- Ignore the child node.
- If the child is a
- Remove from output any menu construct whose submenu label is the empty string.
- Remove from output any menu item construct representing a command whose Label is the empty string.
- Collapse all sequences of two or more adjacent separators in output to a single separator.
- If the first menu item construct in output is a separator, then remove it.
- If the last menu item construct in output is a separator, then remove it.
- Return output.
The type
IDL attribute must reflect the content attribute of the same name, limited to only known values.
The label
IDL attribute must reflect the content attribute of the same name.
4.11.4. The menuitem
element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
menu
element whosetype
attribute is in the popup menu state. - Content model:
- Nothing.
- Tag omission in text/html:
- No end tag.
- Content attributes:
- Global attributes
type
- Type of commandlabel
- User-visible labelicon
- Icon for the commanddisabled
Whether the command or control is disabledchecked
Whether the command or control is checkedradiogroup
Name of group of commands to treat as a radio button groupdefault
- Mark the command as being a default command- Also, the
title
attribute has special semantics on this element. - Allowed ARIA role attribute values:
menuitem
(default - do not set).- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
interface HTMLMenuItemElement : HTMLElement { attribute DOMString type; attribute DOMString label; attribute DOMString icon; attribute boolean disabled; attribute boolean checked; attribute DOMString radiogroup; attribute boolean default; };
The menuitem
element represents a command that the user can invoke from a popup
menu(a context menu).
A menuitem
element that uses one or more of the type
, label
, icon
, disabled
, checked
, and radiogroup
attributes defines a new command.
The type
attribute indicates the kind of
command: either a normal command with an associated action, or a state or option that can be
toggled, or a selection of one item from a list of items.
The attribute is an enumerated attribute with three keywords and states. The
"command
" keyword maps to the Command state, the "checkbox
" keyword maps to the Checkbox state, and the "radio
" keyword maps to the Radio state. The missing value default is the Command state.
- The Command state
- The element represents a normal command with an associated action.
- The Checkbox state
- The element represents a state or option that can be toggled.
- The Radio state
- The element represents a selection of one item from a list of items.
The label
attribute gives the name of the
command, as shown to the user. If the attribute is
specified, it must have a value that is not the empty string.
The icon
attribute gives a picture that
represents the command. If the attribute is specified, the attribute’s value must contain a valid non-empty URL potentially surrounded by spaces. To obtain
the absolute URL of the icon when the attribute’s value is not the empty string, the
attribute’s value must be resolved relative to the element.
When the attribute is absent, or its value is the empty string, or parsing its value fails, there is no icon.
The disabled
attribute is a boolean attribute that, if present, indicates that the command is not available in
the current state.
The distinction between disabled
and hidden
is subtle. A command would be disabled if, in the same
context, it could be enabled if only certain aspects of the situation were changed. A command
would be marked as hidden if, in that situation, the command will never be enabled. For example,
in the context menu for a water faucet, the command "open" might be disabled if the faucet is
already open, but the command "eat" would be marked hidden since the faucet could never be
eaten.
The checked
attribute is a boolean
attribute that, if present, indicates that the command is selected. The attribute must be
omitted unless the type
attribute is in either the Checkbox state or the Radio state.
The radiogroup
attribute gives the
name of the group of commands that will be toggled when the command itself is toggled, for
commands whose type
attribute has the value "radio
". The scope of the name is the child list of the parent element. The
attribute must be omitted unless the type
attribute is in
the Radio state. When specified, the
attribute’s value must be a non-empty string.
The title
attribute gives a hint describing
the command, which might be shown to the user to help him.
The default
attribute indicates, if
present, that the command is the one that would have been invoked if the user had directly
activated the menu’s subject instead of using the menu. The default
attribute is a boolean attribute.
The type
IDL attribute must reflect the content attribute of the same name, limited to only known
values.
The label
, icon
, disabled
, checked
, and radiogroup
, and default
IDL attributes must reflect the respective content attributes of the same name.
If the element’s Disabled State is false
(enabled) then the element’s activation behavior depends on the element’s type
attribute, as follows:
- If the
type
attribute is in the Checkbox state - If the element has a
checked
attribute, the user agent must remove that attribute. Otherwise, the user agent must add achecked
attribute, with the literal value "checked
". - If the
type
attribute is in the Radio state -
If the element has a parent, then the user agent must walk the list of child nodes of that parent
element, and for each node that is a
menuitem
element, if that element has aradiogroup
attribute whose value exactly matches the current element’s (treating missingradiogroup
attributes as if they were the empty string), and has achecked
attribute, must remove that attribute.Then, the element’s
checked
attribute must be set to the literal value "checked
". - Otherwise
- The element’s activation behavior is to do nothing.
Firing a synthetic click
event at the element
does not cause any of the actions described above to happen.
If the element’s Disabled State is true (disabled) then the element has no activation behavior.
The menuitem
element is not rendered except as part of a popup menu.
4.11.5. Context menus
4.11.5.1. Declaring a context menu
The contextmenu
attribute gives the element’s
context menu. The value must be the ID of a menu
element in the same home subtree whose type
attribute is in the popup menu state.
The contextmenu
attribute is "at risk".
If testing during the Candidate Recommendation phase does not identify at least two interoperable implementations
in current shipping browsers of the contextmenu
attribute
it will be removed from the HTML 5.1 Specification.
When a user right-clicks on an element with a contextmenu
attribute, the user agent will first fire a contextmenu
event at the element, and then, if that event is not
canceled, a show
event at the menu
element.
<form name="npc"> <label>Character name: <input name=char type=text contextmenu=namemenu required></label> <menu type=context id=namemenu> <menuitem label="Pick random name" onclick="document.forms.npc.elements.char.value = getRandomName()"> <menuitem label="Prefill other fields based on name" onclick="prefillFields(document.forms.npc.elements.char.value)"> </menu> </form>
This adds two items to the control’s context menu, one called "Pick random name", and one called "Prefill other fields based on name". They invoke scripts that are not shown in the example above.
4.11.5.2. Processing model
Each element has an assigned context menu, which can be null. If an element A has a contextmenu
attribute, and there is
an element with the ID given by A’s contextmenu
attribute’s value in A’s home subtree, and the first such element in tree order is a menu
element whose type
attribute is in the popup menu state, then A’s assigned
context menu is that element. Otherwise, if A has a parent element,
then A’s assigned context menu is the assigned context
menu of its parent element. Otherwise, A’s assigned context
menu is null.
When an element’s context menu is requested (e.g., by the user right-clicking the element, or pressing a context menu key), the user agent must apply the appropriate rules from the following list:
- If the user requested a context menu using a pointing device
- The user agent must fire a trusted event with the name
contextmenu
, that bubbles and is cancelable, and that uses theMouseEvent
interface, at the element for which the menu was requested. The context information of the event must be initialized to the same values as the lastMouseEvent
user interaction event that was fired as part of the gesture that was interpreted as a request for the context menu. - Otherwise
- The user agent must fire a synthetic mouse
event named
contextmenu
that bubbles and is cancelable at the element for which the menu was requested.
Typically, therefore, the firing of the contextmenu
event will be the default action of a mouseup
or keyup
event. The exact
sequence of events is user agent-dependent, as it will vary based on platform conventions.
The default action of the contextmenu
event depends on
whether or not the element for which the menu was requested has a non-null assigned context
menu when the event dispatch has completed, as follows.
If the assigned context menu of the element for which the menu was requested is null, the default action must be for the user agent to show its default context menu, if it has one.
Otherwise, let subject be the element for which the menu was requested, and let menu be the assigned context menu of target immediately after
the contextmenu
event’s dispatch has completed. The user
agent must fire a trusted event with the name show
at menu, using the RelatedEvent
interface,
with the relatedTarget
attribute initialized
to subject. The event must be cancelable.
If this event (the show
event) is not canceled, then
the user agent must build and show the menu for menu with subject as the subject.
The user agent may also provide access to its default context menu, if any, with the context menu shown. For example, it could merge the menu items from the two menus together, or provide the page’s context menu as a submenu of the default menu. In general, user agents are encouraged to de-emphasize their own contextual menu items, so as to give the author’s context menu the appearance of legitimacy — to allow documents to feel like "applications" rather than "mere Web pages".
User agents may provide means for bypassing the context menu processing model, ensuring that
the user can always access the user agent’s default context menus. For example, the user agent could
handle right-clicks that have the Shift key depressed in such a way that it does not fire the contextmenu
event and instead always shows the default
context menu.
The contextMenu
IDL attribute must reflect the contextmenu
content attribute.
<img src="cats.jpeg" alt="Cats" contextmenu=catsmenu> <menu type="context" id="catsmenu"> <menuitem label="Pet the kittens" onclick="kittens.pet()"> <menuitem label="Cuddle with the kittens" onclick="kittens.cuddle()"> <menu label="Feed the kittens"> <menuitem label="Fish" onclick="kittens.feed(fish)"> <menuitem label="Chicken" onclick="kittens.feed(chicken)"> </menu> </menu>
When a user of a mouse-operated visual Web browser right-clicks on the image, the browser might pop up a context menu like this:
When the user clicks the disclosure triangle, such a user agent would expand the context menu in place, to show the browser’s own commands:
4.11.5.3. The RelatedEvent
interfaces
[Constructor(DOMString type, optional RelatedEventInit eventInitDict)] interface RelatedEvent : Event { readonly attribute EventTarget? relatedTarget; }; dictionary RelatedEventInit : EventInit { EventTarget? relatedTarget; };
- event .
relatedTarget
-
Returns the other event target involved in this event. For example, when a
show
event fires on amenu
element, the other event target involved in the event would be the element for which the menu is being shown.
The relatedTarget
attribute must
return the value it was initialized to. When the object is created, this attribute must be
initialized to null. It represents the other event target that is related to the event.
4.11.6. Commands
4.11.6.1. Facets
A command is the abstraction behind menu items, buttons, and links. Once a command is defined, other parts of the interface can refer to the same command, allowing many access points to a single feature to share facets such as the Disabled State.
Commands are defined to have the following facets:
- Label
- The name of the command as seen by the user.
- Access Key
- A key combination selected by the user agent that triggers the command. A command might not have an Access Key.
- Hidden State
- Whether the command is hidden or not (basically, whether it should be shown in menus).
- Disabled State
- Whether the command is relevant and can be triggered or not.
- Action
- The actual effect that triggering the command will have. This could be a scripted event handler, a URL to which to navigate, or a form submission.
User agents may expose the commands that match the following criteria:
- The facet is false (visible)
- The element is in a
Document
that has an associated browsing context. - Neither the element nor any of its ancestors has a
hidden
attribute specified. - The element is not a
menuitem
element, or it is a child of a currently relevantmenu
element, or it has an Access Key.
User agents are encouraged to do this especially for commands that have Access Keys, as a way to advertise those keys to the user.
For example, such commands could be listed in the user agent’s menu bar.
4.11.6.2. Using the a
element to define a command
An a
element with an href
attribute defines a command.
The Label of the command is the string given by the
element’s textContent
IDL attribute.
The Access Key of the command is the element’s assigned access key, if any.
The hidden
attribute, and false otherwise.
The Disabled State facet of the command is true if the element or one of its ancestors is inert, and false otherwise.
The Action of the command, if the element has a
defined activation behavior, is to run synthetic click activation steps on the element. Otherwise, it is just to fire a click
event at the element.
4.11.6.3. Using the button
element to define a command
A button
element always defines a command.
The Label, Access Key, , and Action facets of the command are determined as for a
elements (see the previous section).
The Disabled State of the command is true if the element or one of its ancestors is inert, or if the element’s disabled state is set, and false otherwise.
4.11.6.4. Using the input
element to define a command
An input
element whose type
attribute is in
one of the submit button, reset button, Image
Button, Button, Radio Button, or Checkbox states defines a command.
The Label of the command is determined as follows:
- If the
type
attribute is in one of the submit button, reset button, Image Button, or Button states, then the Label is the string given by thevalue
attribute, if any, and a user agent-dependent, locale-dependent value that the user agent uses to label the button itself if the attribute is absent. - Otherwise, if the element is a labeled control, then the Label is the string given by the
textContent
of the firstlabel
element in tree order whose labeled control is the element in question. (In DOM terms, this is the string given byelement.labels[0].textContent
.) - Otherwise, if the
value
attribute is present, then the Label is the value of that attribute. - Otherwise, the Label is the empty string.
The Access Key of the command is the element’s assigned access key, if any.
The hidden
attribute, and false otherwise.
The Disabled State of the command is true if the element or one of its ancestors is inert, or if the element’s disabled state is set, and false otherwise.
The Action of the command, if the element has a
defined activation behavior, is to run synthetic click activation steps on the element. Otherwise, it is just to fire a click
event at the element.
4.11.6.5. Using the option
element to define a command
An option
element with an ancestor select
element and either no value
attribute or a value
attribute that is not the empty string defines a command.
The Label of the command is the value of the option
element’s label
attribute, if there is
one, or else the value of option
element’s textContent
IDL attribute,
with leading and trailing whitespace
stripped, and with any sequences of two or more space
characters replaced by a single U+0020 SPACE character.
The Access Key of the command is the element’s assigned access key, if any.
The hidden
attribute, and false otherwise.
The Disabled State of the command is true if
the element is disabled, or if its nearest ancestor select
element is disabled, or if it or one
of its ancestors is inert, and false otherwise.
If the option
’s nearest ancestor select
element has a multiple
attribute, the Action of the command is to pick the option
element. Otherwise, the Action is to toggle the option
element.
4.11.6.6. Using the menuitem
element to define a
command
A menuitem
element always defines a command.
The Label of the command is the value of the element’s label
attribute, if there is one, or the empty string if
it doesn’t.
The Access Key of the command is the element’s assigned access key, if any.
The hidden
attribute, and false otherwise.
The Disabled State of the command is true if
the element or one of its ancestors is inert, or if the element has a disabled
attribute, and false otherwise.
The Action of the command, if the element has a
defined activation behavior, is to run synthetic click activation steps on the element. Otherwise, it is just to fire a click
event at the element.
4.11.6.7. Using the accesskey
attribute
on a label
element to define a command
A label
element that has an assigned access key and a labeled
control and whose labeled control defines a command, itself defines a command.
The Label of the command is the string given by the
element’s textContent
IDL attribute.
The Access Key of the command is the element’s assigned access key.
The Disabled State, and Action facets of the command are the same as the respective facets of the element’s labeled control.
,4.11.6.8. Using the accesskey
attribute
on a legend
element to define a command
A legend
element that has an assigned access key and is a child of a fieldset
element that has a descendant that is not a descendant of the legend
element and is neither a label
element nor a legend
element but that defines a command, itself defines a command.
The Label of the command is the string given by the
element’s textContent
IDL attribute.
The Access Key of the command is the element’s assigned access key.
The Disabled State, and Action facets of the command are the same as the respective
facets of the first element in tree order that is a descendant of the parent of the legend
element that defines a command but is not
a descendant of the legend
element and is neither a label
nor a legend
element.
4.11.6.9. Using the accesskey
attribute to define a command on other elements
An element that has an assigned access key defines a command.
If one of the earlier sections that define elements that define commands define that this element defines a command, then that section applies to this element, and this section does not. Otherwise, this section applies to that element.
The Label of the command depends on the element. If
the element is a labeled control, the textContent
of the first label
element in tree order whose labeled control is the
element in question is the Label (in DOM terms, this is
the string given by element.labels[0].textContent
). Otherwise,
the Label is the textContent
of the element
itself.
The Access Key of the command is the element’s assigned access key.
The hidden
attribute, and false otherwise.
The Disabled State of the command is true if the element or one of its ancestors is inert, and false otherwise.
The Action of the command is to run the following steps:
- Run the focusing steps for the element.
- If the element has a defined activation behavior, run synthetic click activation steps on the element.
- Otherwise, if the element does not have a defined activation behavior, fire a
click
event at the element.
4.12. Scripting
Scripts allow authors to add interactivity to their documents.
Authors are encouraged to use declarative alternatives to scripting where possible, as declarative mechanisms are often more maintainable, and many users disable scripting.
details
element could be used. Authors are also encouraged to make their applications degrade gracefully in the absence of scripting support.
4.12.1. The script
element
- Categories:
- Metadata content.
- Flow content.
- Phrasing content.
- Script-supporting element.
- Flow content.
- Contexts in which this element can be used:
- Where metadata content is expected.
- Where phrasing content is expected.
- Where script-supporting elements are expected.
- Where phrasing content is expected.
- Content model:
- If there is no
src
attribute, depends on the value of thetype
attribute, but must match script content restrictions.- If there is a
src
attribute, the element must be either empty or contain only script documentation that also matches script content restrictions. - If there is a
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
src
- Address of the resourcetype
- Type of embedded resourcecharset
- Character encoding of the external script resourceasync
- Execute script in paralleldefer
- Defer script executioncrossorigin
- How the element handles crossorigin requestsnonce
- Cryptographic nonce used in Content Security Policy checks [CSP3] - Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLScriptElement : HTMLElement { attribute DOMString src; attribute DOMString type; attribute DOMString charset; attribute boolean async; attribute boolean defer; attribute DOMString? crossOrigin; attribute DOMString text; attribute DOMString nonce; };
The script
element allows authors to include dynamic script and data blocks in
their documents. The element does not represent content for the
user.
The type
attribute allows customization of the
type of script represented:
-
Omitting the attribute, or setting it to a JavaScript MIME type, means that the script is a classic script, to be interpreted according to the JavaScript Script top-level production. Classic scripts are affected by the
charset
,async
, anddefer
attributes. Authors should omit the attribute, instead of redundantly giving a JavaScript MIME type. -
Setting the attribute to any other value means that the script is a data block, which is not processed. None of the
script
attributes (excepttype
itself) have any effect on data blocks. Authors must use a valid MIME type that is not a JavaScript MIME type to denote data blocks.
The requirement that data blocks must be denoted using a valid MIME type is in place to avoid potential future collisions. If this specification
ever adds additional types of script, they will be triggered by setting the type
attribute to something which is not a MIME type.
By using a valid MIME type now, you ensure that your data block
will not ever be reinterpreted as a different script type, even in future user agents.
Classic scripts may either be embedded inline or may be imported
from an external file using the src
attribute,
which if specified gives the URL of the external script resource to use. If src
is specified, it must be a valid non-empty URL potentially surrounded by spaces. The
contents of inline script
elements, or the external script resource, must conform with the
requirements of the JavaScript specification’s Script production for classic scripts. [ECMA-262]
When used to include data blocks, the data must be embedded inline, the format of the data
must be given using the type
attribute, and the contents of the script
element must
conform to the requirements defined for the format used. The src
, charset
, async
, defer
, crossorigin
, and nonce
attributes must
not be specified.
The charset
attribute gives the character
encoding of the external script resource. The attribute must not be specified if the src
attribute is not present, or if the script is not a classic script.
If the attribute is set, its value
must be an ASCII case-insensitive match for one of the labels of an encoding, and must specify the same encoding as the charset
parameter of the Content-Type metadata of the external
file, if any. [ENCODING]
The async
and defer
attributes are boolean attributes that indicate how the script should be executed. Classic scripts may specify defer
or async
.
There are several possible modes that can be selected using these attributes, and depending on the
script’s type
.
For classic scripts, if the async
attribute is present, then the classic script
will be fetched in parallel to parsing and evaluated as soon as it is available
(potentially before parsing completes). If the async
attribute is not present but the defer
attribute is present, then the classic script will be fetched in parallel and evaluated when the page has finished parsing. If neither attribute is
present, then the script is fetched and evaluated immediately, blocking parsing until these are
both complete.
This is all summarized in the following schematic diagram:
The exact processing details for these attributes are, for mostly historical
reasons, somewhat non-trivial, involving a number of aspects of HTML. The implementation
requirements are therefore by necessity scattered throughout the specification. The algorithms
below (in this section) describe the core of this processing, but these algorithms reference and
are referenced by the parsing rules for script
start and end tags in HTML, in foreign content, and in XML, the rules for the document.write()
method, the handling of scripting, etc.
The defer
attribute may be specified even if the async
attribute is
specified, to cause legacy Web browsers that only support defer
(and not async
) to fall back to the defer
behavior instead of the blocking behavior
that is the default.
The crossorigin
attribute is a CORS settings attribute. For classic scripts, it controls whether error information
will be exposed, when the script is obtained from other origins.
The nonce
attribute represents a
cryptographic nonce ("number used once") which can be used by Content Security Policy to
determine whether or not the script specified by an element will be executed. The value is text. [CSP3]
Changing the src
, type
, charset
, async
, defer
, crossorigin
, and nonce
attributes dynamically has no
direct effect; these attributes are only used at specific times described below.
The IDL attributes src
, type
, charset
, defer
, and nonce
, must each reflect the
respective content attributes of the same name.
The crossOrigin
IDL attribute must reflect the crossorigin
content attribute.
The async
IDL attribute controls whether
the element will execute in parallel or not. If the element’s "non-blocking" flag is
set, then, on getting, the async
IDL attribute must return true, and on
setting, the "non-blocking" flag must first be unset, and then the content attribute must
be removed if the IDL attribute’s new value is false, and must be set to the empty string if the
IDL attribute’s new value is true. If the element’s "non-blocking" flag is not set, the IDL attribute must reflect the async
content attribute.
- script .
text
[ = value ] -
Returns the child text content of the element.
Can be set, to replace the element’s children with the given value.
The IDL attribute text
must return the child text content of the script
element. On setting, it must act the same way as the textContent
IDL attribute.
When inserted using the document.write()
method, script
elements execute (typically blocking further script execution or HTML parsing),
but when inserted using innerHTML
and outerHTML
attributes, they do not
execute at all.
script
elements are used. One embeds an external classic script,
and the other includes some data as a data block.
<script src="game-engine.js"></script> <script type="text/x-game-map"> ........U.........e o............A....e .....A.....AAA....e .A..AAA...AAAAA...e </script>
The data in this case might be used by the script to generate the map of a video game. The data doesn’t have to be used that way, though; maybe the map data is actually embedded in other parts of the page’s markup, and the data block here is just used by the site’s search engine to help users who are looking for particular features in their game maps.
script
element can be used to define a function that is
then used by other parts of the document, as part of a classic script. It also shows how
a script
element can be used to invoke script while the document is being parsed, in this
case to initialize the form’s output.
<script> function calculate(form) { var price = 52000; if (form.elements.brakes.checked) price += 1000; if (form.elements.radio.checked) price += 2500; if (form.elements.turbo.checked) price += 5000; if (form.elements.sticker.checked) price += 250; form.elements.result.value = price; } </script> <form name="pricecalc" onsubmit="return false" onchange="calculate(this)"> <fieldset> <legend>Work out the price of your car</legend> <p>Base cost: £52000.</p> <p>Select additional options:</p> <ul> <li><label><input type=checkbox name=brakes> Ceramic brakes (£1000)</label></li> <li><label><input type=checkbox name=radio> Satellite radio (£2500)</label></li> <li><label><input type=checkbox name=turbo> Turbo charger (£5000)</label></li> <li><label><input type=checkbox name=sticker> "XZ" sticker (£250)</label></li> </ul> <p>Total: £<output name=result></output></p> </fieldset> <script> calculate(document.forms.pricecalc); </script> </form>
4.12.1.1. Processing model
A script
element has several associated pieces of state.
The first is a flag indicating whether or not the script block has been "already started". Initially, script
elements must have this flag unset (script
blocks, when created, are not "already started"). The cloning steps for script
elements
must set the "already started" flag on the copy if it is set on the element being cloned.
The second is a flag indicating whether the element was "parser-inserted".
Initially, script
elements must have this flag unset. It is set by the HTML parser and the XML parser on script
elements they insert and affects the processing of those
elements.
The third is a flag indicating whether the element will "non-blocking". Initially, script
elements must have this flag set. It is unset by the HTML parser and the XML parser on script
elements they insert. In addition, whenever
a script
element whose "non-blocking" flag is set has an async
content
attribute added, the element’s "non-blocking" flag must be unset.
The fourth is a flag indicating whether or not the script block is "ready to be parser-executed". Initially, script
elements must have this flag unset
(script blocks, when created, are not "ready to be parser-executed"). This flag is used only for
elements that are also "parser-inserted", to let the parser know when to execute the
script.
The fifth is the script’s type, which is "classic
". It is
determined when the script is prepared, based on the type
attribute of the
element at that time. Initially, script
elements must have this flag unset.
The sixth is a flag indicating whether or not the script is from an external file. It
is determined when the script is prepared, based on the src
attribute of the
element at that time.
Finally, a script
element has the script’s script, which is a script
resulting from preparing the element. This is set asynchronously after the classic script is fetched. Once it is set, either to a script
in the
case of success or to null in the case of failure, the fetching algorithms will note that the script is ready, which can trigger other actions. The user agent must delay the load event of the element’s node document until the script is ready.
When a script
element that is not marked as being "parser-inserted" experiences one of
the events listed in the following list, the user agent must immediately prepare the script
element:
-
The
script
element gets inserted into a document, at the time the node is inserted according to the DOM, after any otherscript
elements inserted at the same time that are earlier in theDocument
in tree order. -
The
script
element is in aDocument
and a node or document fragment is inserted into thescript
element, after anyscript
elements inserted at that time. -
The
script
element is in aDocument
and has asrc
attribute set where previously the element had no such attribute.
To prepare a script, the user agent must act as follows:
-
If the
script
element is marked as having "already started", then the user agent must abort these steps at this point. The script is not executed. -
If the element has its "parser-inserted" flag set, then set was-parser-inserted to true and unset the element’s "parser-inserted" flag. Otherwise, set was-parser-inserted to false.
This is done so that if parser-inserted
script
elements fail to run when the parser tries to run them, e.g., because they are empty or specify an unsupported scripting language, another script can later mutate them and cause them to run again. -
If was-parser-inserted is true and the element does not have an
async
attribute, then set the element’s "non-blocking" flag to true.This is done so that if a parser-inserted
script
element fails to run when the parser tries to run it, but it is later executed after a script dynamically updates it, it will execute in a non-blocking fashion even if theasync
attribute isn’t set. -
If the element has no
src
attribute, and its child nodes, if any, consist only of comment nodes and emptyText
nodes, then abort these steps at this point. The script is not executed. -
If the element is not in a
Document
, then the user agent must abort these steps at this point. The script is not executed. -
If either:
-
the
script
element has atype
attribute and its value is the empty string, or -
the
script
element has notype
attribute but it has alanguage
attribute and that attribute’s value is the empty string, or -
the
script
element has neither atype
attribute nor alanguage
attribute, then
...let the script block’s type string for this
script
element be "`text/javascript`".Otherwise, if the
script
element has atype
attribute, let the script block’s type string for thisscript
element be the value of that attribute with any leading or trailing sequences of space characters removed.Otherwise, the element has a non-empty
language
attribute; let the script block’s type string for thisscript
element be the concatenation of the string "`text/`" followed by the value of thelanguage
attribute.The
language
attribute is never conforming, and is always ignored if there is atype
attribute present.Determine the script’s type as follows:
-
If the script block’s type string is an ASCII case-insensitive match for any JavaScript MIME type, the script’s type is "
classic
". -
If neither of the above conditions are true, then abort these steps at this point. No script is executed.
-
-
If was-parser-inserted is true, then flag the element as "parser-inserted" again, and set the element’s "non-blocking" flag to false.
-
The user agent must set the element’s "already started" flag.
-
If the element is flagged as "parser-inserted", but the element’s node document is not the
Document
of the parser that created the element, then abort these steps. -
If scripting is disabled for the
script
element, then abort these steps at this point. The script is not executed.The definition of scripting is disabled means that, amongst others, the following scripts will not execute: scripts in
XMLHttpRequest
'sresponseXML
documents, scripts inDOMParser
-created documents, scripts in documents created byXSLTProcessor
’stransformToDocument
feature, and scripts that are first inserted by a script into aDocument
that was created using thecreateDocument()
API. [XHR] [DOM-Parsing] [DOM] -
If the
script
element does not have asrc
content attribute, and the Should element’s inline behavior be blocked by Content Security Policy? algorithm returns "Blocked
" when executed upon thescript
element, "script
", and thescript
element’s child text content, then abort these steps. The script is not executed. [CSP3] -
If the
script
element has anevent
attribute and afor
attribute, and the script’s type is "classic
", then run these substeps:-
Let for be the value of the
for
attribute. -
Let event be the value of the
event
attribute. -
Strip leading and trailing whitespace from event and for.
-
If for is not an ASCII case-insensitive match for the string "
window
", then the user agent must abort these steps at this point. The script is not executed. -
If event is not an ASCII case-insensitive match for either the string "
onload
" or the string "`onload()`", then the user agent must abort these steps at this point. The script is not executed.
-
-
If the
script
element has acharset
attribute, then let encoding be the result of getting an encoding from the value of thecharset
attribute.If the
script
element does not have acharset
attribute, or if getting an encoding failed, let encoding be the same as the encoding of the document itself. -
Let CORS setting be the current state of the element’s
crossorigin
content attribute. -
If the
script
element has anonce
attribute, then let cryptographic nonce be that attribute’s value.Otherwise, let cryptographic nonce be the empty string.
-
Let parser state be "
parser-inserted
" if thescript
element has been flagged as "parser-inserted", and "`not parser-inserted`" otherwise. -
Let settings be the element’s node document’s
Window
object’s environment settings object. -
If the element has a
src
content attribute, run these substeps:-
Let src be the value of the element’s
src
attribute. -
If src is the empty string, queue a task to fire a simple event named
error
at the element, and abort these steps. -
Set the element’s from an external file flag.
-
Parse src relative to the element’s node document.
-
If the previous step failed, queue a task to fire a simple event named
error
at the element, and abort these steps.Otherwise, let url be the resulting URL record.
-
Switch on the script’s type:
- `"classic"`
- Fetch a classic script given url, CORS setting, cryptographic nonce, parser state, settings, and encoding.
For performance reasons, user agents may start fetching the classic script (as defined above) as the
src
attribute is set, instead, in the hope that the element will be inserted into the document (and that thecrossorigin
attribute won’t change value in the meantime). Either way, once the element is inserted into the document, the load must have started as described in this step. If the UA performs such prefetching, but the element is never inserted in the document, or thesrc
attribute is dynamically changed, or thecrossorigin
attribute is dynamically changed, then the user agent will not execute the script so obtained, and the fetching process will have been effectively wasted.
-
-
If the element does not have a
src
content attribute, run these substeps:-
Let source text be the value of the
text
IDL attribute. -
Switch on the script’s type:
- `"classic"`
-
-
Let script be the result of creating a classic script using source text and settings.
-
Set the script’s script to script.
-
-
-
Then, follow the first of the following options that describes the situation:
-
the script’s type src
present?defer
present?async
present?other conditions `"classic"` yes yes no element flagged as "parser-inserted" Document
of the parser that created the element.When the the script is ready, set the element’s "ready to be parser-executed" flag. The parser will handle executing the script.
-
the script’s type src
present?defer
present?async
present?other conditions `"classic"` yes no no element flagged as "parser-inserted" Document
of the parser that created the element. (There can only be one such script perDocument
at a time.)When the script is ready, set the element’s "ready to be parser-executed" flag. The parser will handle executing the script.
-
the script’s type src
present?defer
present?async
present?other conditions `"classic"` yes yes or no no "non-blocking" flag not set on element script
element at the time the prepare a script algorithm started.When the script is ready, run the following steps:
-
If the element is not now the first element in the list of scripts that will execute in order as soon as possible to which it was added above, then mark the element as ready but abort these steps without executing the script yet.
-
Execution: Execute the script block corresponding to the first script element in this list of scripts that will execute in order as soon as possible.
-
Remove the first element from this list of scripts that will execute in order as soon as possible.
-
If this list of scripts that will execute in order as soon as possible is still not empty and the first entry has already been marked as ready, then jump back to the step labeled Execution.
-
-
the script’s type src
present?defer
present?async
present?other conditions `"classic"` yes yes or no yes or no n/a script
element at the time the prepare a script algorithm started.When the script is ready, execute the script block and then remove the element from the set of scripts that will execute as soon as possible.
-
the script’s type src
present?defer
present?async
present?other conditions `"classic"` no yes or no yes or no All of the following: -
element flagged as "parser-inserted"
-
an XML parser or an HTML parser whose script nesting level is not greater than one created the
script
-
the
Document
of the XML parser or HTML parser that created thescript
has a style sheet that is blocking scripts
Document
of the parser that created the element. (There can only be one such script perDocument
at a time.)Set the element’s "ready to be parser-executed" flag. The parser will handle executing the script.
-
- Otherwise
- Immediately execute the script block, even if other scripts are already executing.
The pending parsing-blocking script of a Document
is used by the Document
's
parser(s).
If a script
element that blocks a parser gets moved to another Document
before it would normally have stopped blocking that parser, it nonetheless continues blocking that
parser until the condition that causes it to be blocking the parser no longer applies (e.g., if
the script is a pending parsing-blocking script because there was a style sheet that is blocking scripts when it was parsed, but then the script is moved to
another Document
before the style sheet loads, the script still blocks the parser until the
style sheets are all loaded, at which time the script executes and the parser is unblocked).
When the user agent is required to execute a script block, it must run the following steps:
-
If the element is flagged as "parser-inserted", but the element’s node document is not the
Document
of the parser that created the element, then abort these steps. -
If the script’s script is null, fire a simple event named
error
at the element, and abort these steps. -
If the script is from an external file, then increment the ignore-destructive-writes counter of the
script
element’s node document. Let neutralized doc be thatDocument
. -
Let old script element be the value to which the
script
element’s node document’scurrentScript
object was most recently set. -
Switch on the script’s type:
- `"classic"`
-
-
Set the
script
element’s node document’scurrentScript
attribute to thescript
element.This does not use the in a document check, as the
script
element could have been removed from the document prior to execution, and in that scenariocurrentScript
still needs to point to it. -
Run the classic script given by the script’s script.
-
-
Set the
script
element’s node document’scurrentScript
object to old script element. -
Decrement the ignore-destructive-writes counter of neutralized doc, if it was incremented in the earlier step.
-
If the script’s type is "
classic
" and the script is from an external file, fire a simple event namedload
at thescript
element.Otherwise queue a task to fire a simple event named
load
at thescript
element.
4.12.1.2. Scripting languages
A JavaScript MIME type is a MIME type string that is one of the following and refers to JavaScript: [ECMA-262]
application/ecmascript
application/javascript
application/x-ecmascript
application/x-javascript
text/ecmascript
text/javascript
text/javascript1.0
text/javascript1.1
text/javascript1.2
text/javascript1.3
text/javascript1.4
text/javascript1.5
text/jscript
text/livescript
text/x-ecmascript
text/x-javascript
User agents must recognize all JavaScript MIME types.
User agents may support other MIME types for other languages, but must not support other MIME types for the languages in the list above. User agents are not required to support JavaScript. The processing model for languages other than JavaScript is outside the scope of this specification.
The following MIME types (with or without parameters) must not be interpreted as scripting languages:
-
`text/plain`
-
`text/xml`
-
`application/octet-stream`
-
`application/xml`
These types are explicitly listed here because they are poorly-defined types that are nonetheless likely to be used as formats for data blocks, and it would be problematic if they were suddenly to be interpreted as script by a user agent.
When examining types to determine if they represent supported languages, user agents must not ignore MIME parameters. Types are to be compared including all parameters.
For example, types that include the charset
parameter will not be
recognized as referencing any of the scripting languages listed above.
4.12.1.3. Restrictions for contents of script
elements
The easiest and safest way to avoid the rather strange restrictions described in
this section is to always escape "`<!--`" as "`<\!--`", "`<script`" as "`<\script`",
and "`</script`" as "`<\/script`" when these sequences appear in literals in scripts (e.g.,
in strings, regular expressions, or comments), and to avoid writing code that uses such constructs
in expressions. Doing so avoids the pitfalls that the restrictions in this section are prone to
triggering: namely, that, for historical reasons, parsing of script
blocks in HTML is a
strange and exotic practice that acts unintuitively in the face of these sequences.
The textContent
of a script
element must match the script
production in
the following ABNF, the character set for which is Unicode. [ABNF]
script = outer *( comment-open inner comment-close outer ) outer = < any string that doesn’t contain a substring that matches not-in-outer > not-in-outer = comment-open inner = < any string that doesn’t contain a substring that matches not-in-inner > not-in-inner = comment-close / script-open comment-open = "<!--" comment-close = "-->" script-open = "<" s c r i p t tag-end s = %x0053 ; U+0053 LATIN CAPITAL LETTER S s =/ %x0073 ; U+0073 LATIN SMALL LETTER S c = %x0043 ; U+0043 LATIN CAPITAL LETTER C c =/ %x0063 ; U+0063 LATIN SMALL LETTER C r = %x0052 ; U+0052 LATIN CAPITAL LETTER R r =/ %x0072 ; U+0072 LATIN SMALL LETTER R i = %x0049 ; U+0049 LATIN CAPITAL LETTER I i =/ %x0069 ; U+0069 LATIN SMALL LETTER I p = %x0050 ; U+0050 LATIN CAPITAL LETTER P p =/ %x0070 ; U+0070 LATIN SMALL LETTER P t = %x0054 ; U+0054 LATIN CAPITAL LETTER T t =/ %x0074 ; U+0074 LATIN SMALL LETTER T tag-end = %x0009 ; U+0009 CHARACTER TABULATION (tab) tag-end =/ %x000A ; U+000A LINE FEED (LF) tag-end =/ %x000C ; U+000C FORM FEED (FF) tag-end =/ %x0020 ; U+0020 SPACE tag-end =/ %x002F ; U+002F SOLIDUS (/) tag-end =/ %x003E ; U+003E GREATER-THAN SIGN (>)
When a script
element contains script documentation, there are further restrictions on
the contents of the element, as described in the section below.
var example = 'Consider this string: <!-- <script>'; console.log(example);
If one were to put this string directly in a script
block, it would violate the
restrictions above:
<script> var example = 'Consider this string: <!-- <script>'; console.log(example); </script>
The bigger problem, though, and the reason why it would violate those restrictions, is that
actually the script would get parsed weirdly: the script block above is not terminated.
That is, what looks like a "`</script>`" end tag in this snippet is actually still part of
the script
block. The script doesn’t execute (since it’s not terminated); if it somehow were
to execute, as it might if the markup looked as follows, it would fail because the script is not
valid JavaScript:
<script> var example = 'Consider this string: <!-- <script>'; console.log(example); </script> <!-- despite appearances, this is actually part of the script still! --> <script> ... // this is the same script block still... </script>
What is going on here is that for legacy reasons, "`<!--`" and "`<script`" strings in script
elements in HTML need to be balanced in order for the parser to consider closing the
block.
By escaping the problematic strings as mentioned at the top of this section, the problem is avoided entirely:
<script> var example = 'Consider this string: <\!-- <\script>'; console.log(example); </script> <!-- this is just a comment between script blocks --> <script> ... // this is a new script block </script>
It is possible for these sequences to naturally occur in script expressions, as in the following examples:
if (x<!--y) { ... } if ( player<script ) { ... }
In such cases the characters cannot be escaped, but the expressions can be rewritten so that the sequences don’t occur, as in:
if (x < !--y) { ... } if (!--y > x) { ... } if (!(--y) > x) { ... } if (player < script) { ... } if (script > player) { ... }
Doing this also avoids a different pitfall as well: for related historical reasons, the string "`<!--`" in classic scripts is actually treated as a line comment start, just like "`//`".
4.12.1.4. Inline documentation for external scripts
If a script
element’s src
attribute is specified, then the contents of the script
element, if any, must be such that the value of the text
IDL
attribute, which is derived from the element’s contents, matches the documentation
production in
the following ABNF, the character set for which is Unicode. [ABNF]
documentation = *( *( space / tab / comment ) [ line-comment ] newline ) comment = slash star *( not-star / star not-slash ) 1*star slash line-comment = slash slash *not-newline ; characters tab = %x0009 ; U+0009 CHARACTER TABULATION (tab) newline = %x000A ; U+000A LINE FEED (LF) space = %x0020 ; U+0020 SPACE star = %x002A ; U+002A ASTERISK (*) slash = %x002F ; U+002F SOLIDUS (/) not-newline = %x0000-0009 / %x000B-10FFFF ; a Unicode character other than U+000A LINE FEED (LF) not-star = %x0000-0029 / %x002B-10FFFF ; a Unicode character other than U+002A ASTERISK (*) not-slash = %x0000-002E / %x0030-10FFFF ; a Unicode character other than U+002F SOLIDUS (/)
This corresponds to putting the contents of the element in JavaScript comments.
This requirement is in addition to the earlier restrictions on the syntax of
contents of script
elements.
src
attribute.
<script src="cool-effects.js"> // create new instances using: // var e = new Effect(); // start the effect using .play, stop using .stop: // e.play(); // e.stop(); </script>
4.12.1.5. Interaction of script
elements and XSLT
This section is non-normative.
This specification does not define how XSLT interacts with the script
element.
However, in the absence of another specification actually defining this, here are some guidelines
for implementors, based on existing implementations:
-
When an XSLT transformation program is triggered by an `<?xml-stylesheet?>` processing instruction and the browser implements a direct-to-DOM transformation,
script
elements created by the XSLT processor need to be marked "parser-inserted" and run in document order (modulo scripts markeddefer
orasync
), immediately, as the transformation is occurring. -
The
XSLTProcessor.transformToDocument()
method adds elements to aDocument
that is not in a browsing context, and, accordingly, anyscript
elements they create need to have their "already started" flag set in the prepare a script algorithm and never get executed (scripting is disabled). Suchscript
elements still need to be marked "parser-inserted", though, such that theirasync
IDL attribute will return false in the absence of anasync
content attribute. -
The
XSLTProcessor.transformToFragment()
method needs to create a fragment that is equivalent to one built manually by creating the elements usingdocument.createElementNS()
. For instance, it needs to createscript
elements that aren’t "parser-inserted" and that don’t have their "already started" flag set, so that they will execute when the fragment is inserted into a document.
The main distinction between the first two cases and the last case is that the first two
operate on Document
s and the last operates on a fragment.
4.12.2. The noscript
element
- Categories:
- Metadata content.
- Flow content.
- Phrasing content.
- Flow content.
- Contexts in which this element can be used:
- In a
head
element of an HTML document, if there are no ancestornoscript
elements.- Where phrasing content is expected in HTML documents, if there are no ancestor
noscript
elements. - Where phrasing content is expected in HTML documents, if there are no ancestor
- Content model:
- When scripting is disabled, in a
head
element: in any order, zero or morelink
elements, zero or morestyle
elements, and zero or moremeta
elements.- When scripting is disabled, not in a
head
element: transparent, but there must be nonoscript
element descendants.- Otherwise: text that conforms to the requirements given in the prose.
- When scripting is disabled, not in a
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
- Uses
HTMLElement
.
The noscript
element represents nothing if scripting is enabled, and represents its children if scripting is disabled. It is used to present different
markup to user agents that support scripting and those that don’t support scripting, by affecting
how the document is parsed.
When used in HTML documents, the allowed content model is as follows:
-
In a
head
element, if scripting is disabled for thenoscript
element -
The
noscript
element must contain onlylink
,style
, andmeta
elements. -
In a
head
element, if scripting is enabled for thenoscript
element -
The
noscript
element must contain only text, except that invoking the HTML fragment parsing algorithm with thenoscript
element as the context element and the text contents as the input must result in a list of nodes that consists only oflink
,style
, andmeta
elements that would be conforming if they were children of thenoscript
element, and no parse errors. -
Outside of
head
elements, if scripting is disabled for thenoscript
element -
The
noscript
element’s content model is transparent, with the additional restriction that anoscript
element must not have anoscript
element as an ancestor (that is,noscript
can’t be nested). -
Outside of
head
elements, if scripting is enabled for thenoscript
element -
The
noscript
element must contain only text, except that the text must be such that running the following algorithm results in a conforming document with nonoscript
elements and noscript
elements, and such that no step in the algorithm throws an exception or causes an HTML parser to flag a parse error:-
Remove every
script
element from the document. -
Make a list of every
noscript
element in the document. For everynoscript
element in that list, perform the following steps:-
Let s be the concatenation of all the
Text
node children of thenoscript
element. -
Set the
outerHTML
attribute of thenoscript
element to the value of s. (This, as a side-effect, causes thenoscript
element to be removed from the document.) [DOM-Parsing]
-
-
All these contortions are required because, for historical reasons, the noscript
element is handled differently by the HTML parser based on whether scripting was enabled or not when the parser was invoked.
The noscript
element must not be used in XML documents.
The noscript
element is only effective in the HTML syntax, it has no effect in the XHTML syntax.
This is because the way it works is by essentially "turning off" the parser when scripts are
enabled, so that the contents of the element are treated as pure text and not as real elements.
XML does not define a mechanism by which to do this.
The noscript
element has no other requirements. In particular, children of the noscript
element are not exempt from §4.10.22 Form submission, scripting, and so forth, even when scripting is enabled for the element.
noscript
element is used to provide fallback for a script.
<form action="calcSquare.php"> <p> <label for=x>Number</label>: <input id="x" name="x" type="number"> </p> <script> var x = document.getElementById('x'); var output = document.createElement('p'); output.textContent = 'Type a number; it will be squared right then!'; x.form.appendChild(output); x.form.onsubmit = function () { return false; } x.oninput = function () { var v = x.valueAsNumber; output.textContent = v + ' squared is ' + v * v; }; </script> <noscript> <input type=submit value="Calculate Square"> </noscript> </form>
When script is disabled, a button appears to do the calculation on the server side. When script is enabled, the value is computed on-the-fly instead.
The noscript
element is a blunt instrument. Sometimes, scripts might be enabled,
but for some reason the page’s script might fail. For this reason, it’s generally better to avoid
using noscript
, and to instead design the script to change the page from being a
scriptless page to a scripted page on the fly, as in the next example:
<form action="calcSquare.php"> <p> <label for=x>Number</label>: <input id="x" name="x" type="number"> </p> <input id="submit" type=submit value="Calculate Square"> <script> var x = document.getElementById('x'); var output = document.createElement('p'); output.textContent = 'Type a number; it will be squared right then!'; x.form.appendChild(output); x.form.onsubmit = function () { return false; } x.oninput = function () { var v = x.valueAsNumber; output.textContent = v + ' squared is ' + v * v; }; var submit = document.getElementById('submit'); submit.parentNode.removeChild(submit); </script> </form>
The above technique is also useful in XHTML, since noscript
is not supported in the XHTML syntax.
4.12.3. The template
element
- Categories:
- Metadata content.
- Flow content.
- Phrasing content.
- Script-supporting element.
- Flow content.
- Contexts in which this element can be used:
- Where metadata content is expected.
- Where phrasing content is expected.
- Where script-supporting elements are expected.
- As a child of a
colgroup
element that doesn’t have aspan
attribute. - Where phrasing content is expected.
- Content model:
- Either: Metadata content.
- Or: Flow content.
- Or: The content model of
ol
andul
elements.- Or: The content model of
dl
elements.- Or: The content model of
figure
elements.- Or: The content model of
ruby
elements.- Or: The content model of
object
elements.- Or: The content model of
video
andaudio
elements.- Or: The content model of
table
elements.- Or: The content model of
colgroup
elements.- Or: The content model of
thead
,tbody
, andtfoot
elements.- Or: The content model of
tr
elements.- Or: The content model of
fieldset
elements.- Or: The content model of
select
elements.- Or: The content model of
details
elements.- Or: The content model of
menu
elements whosetype
attribute is in the popup menu state. - Or: Flow content.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
- None
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLTemplateElement : HTMLElement { readonly attribute DocumentFragment content; };
The template
element is used to declare fragments of HTML that can be cloned and
inserted in the document by script.
Templates provide a method for declaring inert DOM subtrees and manipulating them to instantiate document fragments with identical contents.
When web pages dynamically alter the contents of their documents (e.g., in response to user interaction or new data arriving from the server), it is common that they require fragments of HTML which may require further modification before use, such as the insertion of values appropriate for the usage context.
The template
element allows for the declaration of document fragments which are
unused by the document when loaded, but are parsed as HTML and are available at runtime for use by
the web page.
In a rendering, the template
element represents nothing.
- template .
content
-
Returns the contents of the
template
, which are stored in aDocumentFragment
associated with a differentDocument
so as to avoid thetemplate
contents interfering with the mainDocument
. (For example, this avoids form controls from being submitted, scripts from executing, and so forth.)
Each template
element has an associated DocumentFragment
object that
is its template contents. When a template
element is created, the user
agent must run the following steps to establish the template contents:
- Let doc be the
template
element’s node document’s appropriate template contents owner document. - Create a
DocumentFragment
object whose node document is doc. - Set the
template
element’s template contents to the newly createdDocumentFragment
object.
A Document
doc’s appropriate template contents owner
document is the Document
returned by the following algorithm:
-
If doc is not a
Document
created by this algorithm, run these substeps:-
If doc does not yet have an associated inert template document then run these substeps:
- Let new doc be a new
Document
(that does not have a browsing context). This is "aDocument
created by this algorithm" for the purposes of the step above. - If doc is an HTML document, mark new doc as an HTML document also.
- Let doc’s associated inert template document be new doc.
- Let new doc be a new
- Set doc to doc’s associated inert template document.
Each
Document
not created by this algorithm thus gets a singleDocument
to act as its proxy for owning the template contents of all itstemplate
elements, so that they aren’t in a browsing context and thus remain inert (e.g., scripts do not run). Meanwhile,template
elements insideDocument
objects that are created by this algorithm just reuse the sameDocument
owner for their contents. -
- Return doc.
The adopting steps (with node and oldDocument as parameters) for template
elements
are the following:
-
Let doc be node’s node document’s appropriate template contents owner document.
node’s node document is the
Document
object that node was just adopted into. - Adopt node’s template contents (a
DocumentFragment
object) into doc.
The content
IDL attribute must return
the template
element’s template contents.
The cloning steps for a template
element node being cloned to a copy copy must run the
following steps:
- If the clone children flag is not set in the calling clone algorithm, abort these steps.
- Let copied contents be the result of cloning all the children of node’s template contents, with document set to copy’s template contents’s node document, and with the clone children flag set.
- Append copied contents to copy’s template contents.
template
to provide the element structure instead of manually generating the
structure from markup.
<!DOCTYPE html> <title>Cat data</title> <script> // Data is hard-coded here, but could come from the server var data = [ { name: 'Pillar', color: 'Ticked Tabby', sex: 'Female (neutered)', legs: 3 }, { name: 'Hedral', color: 'Tuxedo', sex: 'Male (neutered)', legs: 4 }, ]; </script> <table> <thead> <tr> <th>Name <th>Color <th>Sex <th>Legs <tbody> <template id="row"> <tr><td><td><td><td> </template> </table> <script> var template = document.querySelector('#row'); for (var i = 0; i < data.length; i += 1) { var cat = data[i]; var clone = template.content.cloneNode(true); var cells = clone.querySelectorAll('td'); cells[0].textContent = cat.name; cells[1].textContent = cat.color; cells[2].textContent = cat.sex; cells[3].textContent = cat.legs; template.parentNode.appendChild(clone); } </script>
This example uses cloneNode()
on the template
’s contents; it could
equivalently have used document.importNode()
, which does the same thing. The only
difference between these two APIs is when the node document is updated: with cloneNode()
it is updated when the nodes are appended with appendChild()
, with document.importNode()
it is updated when the nodes
are cloned.
4.12.3.1. Interaction of template
elements with XSLT and XPath
This section is non-normative.
This specification does not define how XSLT and XPath interact with the template
element. However, in the absence of another specification actually defining this, here are some
guidelines for implementors, which are intended to be consistent with other processing described
in this specification:
- An XSLT processor based on an XML parser that acts as described
in this specification needs to act as if
template
elements contain as descendants their template contents for the purposes of the transform. - An XSLT processor that outputs a DOM needs to ensure that nodes that would go into a
template
element are instead placed into the element’s template contents. - XPath evaluation using the XPath DOM API when applied to a
Document
parsed using the HTML parser or the XML parser described in this specification needs to ignore template contents.
4.12.4. The canvas
element
- Categories:
- Flow content.
- Phrasing content.
- Embedded content.
- Palpable content.
- Phrasing content.
- Contexts in which this element can be used:
- Where embedded content is expected.
- Content model:
- Transparent.
- Tag omission in text/html:
- Neither tag is omissible
- Content attributes:
- Global attributes
width
- Horizontal dimensionheight
- Vertical dimension - Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA state and property attributes:
- Global aria-* attributes
- Any
aria-*
attributes applicable to the allowed roles. - Any
- DOM interface:
-
typedef (CanvasRenderingContext2D or WebGLRenderingContext) RenderingContext; interface HTMLCanvasElement : HTMLElement { attribute unsigned long width; attribute unsigned long height; RenderingContext? getContext(DOMString contextId, any... arguments); boolean probablySupportsContext(DOMString contextId, any... arguments); DOMString toDataURL(optional DOMString type, any... arguments); void toBlob(BlobCallback _callback, optional DOMString type, any... arguments); }; callback BlobCallback = void (Blob? blob);
The canvas
element provides scripts with a resolution-dependent bitmap canvas,
which can be used for rendering graphs, game graphics, art, or other visual images on the fly.
Authors should not use the canvas
element in a document when a more suitable
element is available. For example, it is inappropriate to use a canvas
element to
render a page heading: if the desired presentation of the heading is graphically intense, it
should be marked up using appropriate elements (typically h1
) and then styled using
CSS and supporting technologies such as Web Components.
When authors use the canvas
element, they must also provide content that, when
presented to the user, conveys essentially the same function or purpose as the canvas
's bitmap. This content may be placed as content of the canvas
element. The contents of the canvas
element, if any, are the element’s fallback
content.
In interactive visual media, if scripting is enabled for
the canvas
element, and if support for canvas
elements has been enabled,
the canvas
element represents embedded content consisting
of a dynamically created image, the element’s bitmap.
In non-interactive, static, visual media, if the canvas
element has been
previously associated with a rendering context (e.g., if the page was viewed in an interactive
visual medium and is now being printed, or if some script that ran during the page layout process
painted on the element), then the canvas
element represents embedded content with the element’s current bitmap and size. Otherwise, the element
represents its fallback content instead.
In non-visual media, and in visual media if scripting is
disabled for the canvas
element or if support for canvas
elements
has been disabled, the canvas
element represents its fallback
content instead.
When a canvas
element represents embedded content, the
user can still focus descendants of the canvas
element (in the fallback
content). When an element is focused, it is the target of keyboard interaction
events (even though the element itself is not visible). This allows authors to make an interactive
canvas keyboard-accessible: authors should have a one-to-one mapping of interactive regions to focusable areas in the fallback content. (Focus has no
effect on mouse interaction events.) [UIEVENTS]
An element whose nearest canvas
element ancestor is being rendered and represents embedded content is an element that is being used as
relevant canvas fallback content.
The canvas
element has two attributes to control the size of the element’s bitmap: width
and height
. These attributes, when specified, must have
values that are valid non-negative integers. The rules for parsing non-negative integers must be used to obtain their
numeric values. If an attribute is missing, or if parsing its value returns an error, then the
default value must be used instead. The width
attribute defaults to 300, and the height
attribute
defaults to 150.
The intrinsic dimensions of the canvas
element when it represents embedded content are equal to the dimensions of the
element’s bitmap.
The user agent must use a square pixel density consisting of one pixel of image data per
coordinate space unit for the bitmaps of a canvas
and its rendering contexts.
A canvas
element can be sized arbitrarily by a style sheet, its
bitmap is then subject to the object-fit CSS property. [CSS3-IMAGES]
The bitmaps of canvas
elements, the bitmaps of ImageBitmap
objects,
as well as some of the bitmaps of rendering contexts, such as those described in the section on
the CanvasRenderingContext2D
object below, have an origin-clean flag, which can be set to true or false.
Initially, when the canvas
element or ImageBitmap
object is created,
its bitmap’s origin-clean flag must be set to
true.
A canvas
bitmap can also have a hit region list, as described in the CanvasRenderingContext2D
section below.
A canvas
element can have a rendering context bound to it. Initially, it does not
have a bound rendering context. To keep track of whether it has a rendering context or not, and
what kind of rendering context it is, a canvas
also has a canvas context mode,
which is initially none but can be changed to either 2d, webgl by algorithms
defined in this specification.
When its canvas context mode is none, a canvas
element has no rendering context,
and its bitmap must be fully transparent black with an intrinsic width equal to the numeric value
of the element’s width
attribute and an intrinsic height equal to the numeric value of the element’s height
attribute, those values being interpreted in CSS pixels, and being updated as the attributes are
set, changed, or removed.
When a canvas
element represents embedded content, it provides
a paint source whose width is the element’s intrinsic width, whose height is
the element’s intrinsic height, and whose appearance is the element’s bitmap.
Whenever the width
and height
content attributes are set, removed, changed, or
redundantly set to the value they already have, if the canvas context mode is 2d, the user agent must set bitmap dimensions to the numeric values of
the width
and height
content attributes.
The width
and height
IDL attributes must reflect the
respective content attributes of the same name, with the same defaults.
- context = canvas .
getContext
(contextId [, ... ] ) -
Returns an object that exposes an API for drawing on the canvas. The first argument specifies the desired API, either "
2d
" or "webgl
". Subsequent arguments are handled by that API.The list of defined contexts is given on the WHATWG Wiki CanvasContexts page. [WHATWGWIKI]
Example contexts are the "
2d
" [CANVAS-2D] and the "webgl
" context [WEBGL].Returns null if the given context ID is not supported or if the canvas has already been initialized with some other (incompatible) context type (e.g., trying to get a "
2d
" context after getting a "webgl
" context). - supported = canvas .
probablySupportsContext
(contextId [, ... ] ) -
Returns false if calling
getContext()
with the same arguments would definitely return null, and true otherwise.This return value is not a guarantee that
getContext()
will or will not return an object, as conditions (e.g., availability of system resources) can vary over time.
The getContext(contextId, arguments...)
method of the canvas
element, when invoked,
must run the steps in the cell of the following table whose column header describes the canvas
element’s canvas context mode and whose row header describes the method’s first argument.
none | 2d | webgl | |
---|---|---|---|
"2d "
|
Set the | Return the same object as was return the last time the method was invoked with this same first argument. | Return null. |
"webgl ", if the user agent supports the WebGL feature in its current configuration
| Follow the instructions given in the WebGL specification’s Context Creation section to
obtain either a WebGLRenderingContext or null; if the returned value is null,
then return null and abort these steps, otherwise, set the canvas element’s context mode to webgl, set the new WebGLRenderingContext object’s context mode to webgl, and return the WebGLRenderingContext object‡ [WEBGL]
| Return null. | Return the same object as was return the last time the method was invoked with this same first argument. |
A vendor-specific extension* | Behave as defined for the extension. | Behave as defined for the extension. | Behave as defined for the extension. |
An unsupported value† | Return null. | Return null. | Return null. |
* Vendors may define experimental contexts using the syntax vendorname-context
, for example, moz-3d
.
† For example, the "webgl
" value in the case of a user agent having exhausted the
graphics hardware’s abilities and having no software fallback implementation.
‡ The second (and subsequent) argument(s) to the method, if any, are ignored in all cases except this one. See the WebGL specification for details.
There is no known native implementation of the probablySupportsContext()
method. Therefore this feature should not be relied upon.
The probablySupportsContext(contextId, arguments...)
method of the canvas
element, when
invoked, must return false if calling getContext()
on
the same object and with the same arguments would definitely return null at this time, and true
otherwise.
- url = canvas .
toDataURL
( [ type, ... ] ) -
Returns a
data:
URL for the image in the canvas.The first argument, if provided, controls the type of the image to be returned (e.g., PNG or JPEG). The default is
image/png
; that type is also used if the given type isn’t supported. The other arguments are specific to the type, and control the way that the image is generated, as given in the table below.When trying to use types other than "
image/png
", authors can check if the image was really returned in the requested format by checking to see if the returned string starts with one of the exact strings "data:image/png,
" or "data:image/png;
". If it does, the image is PNG, and thus the requested type was not supported. (The one exception to this is if the canvas has either no height or no width, in which case the result might simply be "data:,
".) - canvas .
toBlob
(callback [, type, ... ] ) -
Creates a
Blob
object representing a file containing the image in the canvas, and invokes a callback with a handle to that object.The second argument, if provided, controls the type of the image to be returned (e.g., PNG or JPEG). The default is
image/png
; that type is also used if the given type isn’t supported. The other arguments are specific to the type, and control the way that the image is generated, as given in the table below.
The toDataURL()
method must run the
following steps:
- If the
canvas
element’s bitmap’s origin-clean flag is set to false, throw a "SecurityError
"DOMException
and abort these steps. - If the
canvas
element’s bitmap has no pixels (i.e., either its horizontal dimension or its vertical dimension is zero) then return the string "data:,
" and abort these steps. (This is the shortestdata:
URL; it represents the empty string in atext/plain
resource.) - Let file be a serialization of the
canvas
element’s bitmap as a file, using the method’s arguments (if any) as the arguments. - Return a
data:
URL representing file. [RFC2397]
The toBlob()
method must run the following
steps:
- If the
canvas
element’s bitmap’s origin-clean flag is set to false, throw a "SecurityError
"DOMException
and abort these steps. - Let callback be the first argument.
- Let arguments be the second and subsequent arguments to the method, if any.
-
If the
canvas
element’s bitmap has no pixels (i.e., either its horizontal dimension or its vertical dimension is zero) then let result be null.Otherwise, let result be a
Blob
object representing a serialization of thecanvas
element’s bitmap as a file, using arguments. [FILEAPI] - Return, but continue running these steps in parallel.
- Queue a task to invoke the
BlobCallback
callback with result as its argument. The task source for this task is the canvas blob serialization task source.
4.12.4.1. Color spaces and color correction
The canvas
APIs must perform color correction at only two points: when rendering
images with their own gamma correction and color space information onto a bitmap, to convert the
image to the color space used by the bitmaps (e.g., using the 2D Context’s drawImage()
method with an HTMLImageElement
object), and when rendering the actual canvas bitmap to the output device.
Thus, in the 2D context, colors used to draw shapes onto the canvas will exactly
match colors obtained through the getImageData()
method.
The toDataURL()
method must not include color space
information in the resources they return. Where the output format allows it, the color of pixels
in resources created by toDataURL()
must match those
returned by the getImageData()
method.
In user agents that support CSS, the color space used by a canvas
element must
match the color space used for processing any colors for that element in CSS.
The gamma correction and color space information of images must be handled in such a way that
an image rendered directly using an img
element would use the same colors as one
painted on a canvas
element that is then itself rendered. Furthermore, the rendering
of images that have no color correction information (such as those returned by the toDataURL()
method) must be rendered with no color
correction.
Thus, in the 2D context, calling the drawImage()
method to render the output of the toDataURL()
method to the canvas, given the appropriate
dimensions, has no visible effect.
4.12.4.2. Serializing bitmaps to a file
When a user agent is to create a serialization of the bitmap as a file, optionally with some given arguments, and optionally with a native flag set, it must create an image file in the format given by the first value of arguments, or, if there are no arguments, in the PNG format. [PNG]
If the native flag is set, or if the bitmap has one pixel per coordinate space unit, then the image file must have the same pixel data (before compression, if applicable) as the bitmap, and if the file format used supports encoding resolution metadata, the resolution of that bitmap (device pixels per coordinate space units being interpreted as image pixels per CSS pixel) must be given as well.
Otherwise, the image file’s pixel data must be the bitmap’s pixel data scaled to one image pixel per coordinate space unit, and if the file format used supports encoding resolution metadata, the resolution must be given as 96dpi (one image pixel per CSS pixel).
If arguments is not empty, the first value must be interpreted as a MIME type giving the format to use. If the type has any parameters, it must be treated as not supported.
For example, the value "image/png
" would mean to generate a PNG
image, the value "image/jpeg
" would mean to generate a JPEG image, and the value
"image/svg+xml
" would mean to generate an SVG image (which would require that the
user agent track how the bitmap was generated, an unlikely, though potentially awesome,
feature).
User agents must support PNG ("image/png
"). User agents may support other types.
If the user agent does not support the requested type, it must create the file using the PNG
format. [PNG]
User agents must convert the provided type to ASCII lowercase before establishing if they support that type.
For image types that do not support an alpha channel, the serialized image must be the bitmap image composited onto a solid black background using the source-over operator.
If the first argument in arguments gives a type corresponding to one of the types given in the first column of the following table, and the user agent supports that type, then the subsequent arguments, if any, must be treated as described in the second cell of that row.
Type | Other arguments | Reference |
---|---|---|
image/jpeg
| The second argument, if it is a number in the range 0.0 to 1.0 inclusive, must be treated as the desired quality level. If it is not a number or is outside that range, the user agent must use its default value, as if the argument had been omitted. | [JPEG] |
For the purposes of these rules, an argument is considered to be a number if it is converted to
an IDL double value by the rules for handling arguments of type any
in the
Web IDL specification. [WEBIDL]
Other arguments must be ignored and must not cause the user agent to throw an exception. A future version of this specification will probably define other parameters to be passed to these methods to allow authors to more carefully control compression settings, image metadata, etc.
4.12.4.3. Security with canvas
elements
This section is non-normative.
Information leakage can occur if scripts from one origin can access information (e.g., read pixels) from images from another origin (one that isn’t the same).
To mitigate this, bitmaps used with canvas
elements and ImageBitmap
objects are defined to have a flag indicating whether they are origin-clean. All bitmaps start with their origin-clean set to true. The flag is set to
false when cross-origin images or fonts are used.
The toDataURL()
, toBlob()
, and getImageData()
methods check the flag and will
throw a "SecurityError
" DOMException
rather than leak cross-origin data.
The value of the origin-clean flag is
propagated from a source canvas
element’s bitmap to a new ImageBitmap
object by createImageBitmap()
. Conversely, a
destination canvas
element’s bitmap will have its origin-clean flags set to false by drawImage
if the source image is an ImageBitmap
object whose bitmap has its origin-clean flag set to false.
The flag can be reset in certain situations; for example, when a CanvasRenderingContext2D
is bound to a new canvas
, the bitmap is cleared
and its flag reset.
4.13. Common idioms without dedicated elements
4.13.1. Subheadings, subtitles, alternative titles and taglines
HTML does not have a dedicated mechanism for marking up subheadings, alternative titles or taglines. Here are the suggested alternatives.h1
–h6
elements must not be used to markup subheadings, subtitles, alternative titles and taglines unless intended to be the heading for a new section or subsection.
header
element.
As the author does not want the subtitles to be included the table of contents and they are not intended to signify
the start of a new section, they are marked up using p
elements. A sample CSS styled rendering of the
title and subtitles is provided below the code example.
<header> <h1>HTML 5.1 Nightly</h1> <p>A vocabulary and associated APIs for HTML and XHTML</p> <p>Editor’s Draft 9 May 2013</p> </header>
<h1>The Lord of the Rings: The Two Towers</h1>
span
element,
allowing it to be styled differently from the rest of the title. A br
element is used to
place the album title on a new line. A sample CSS styled rendering of the heading is provided
below the code example.
<h1>Ramones <br> <span>Hey! Ho! Let’s Go</span> </h1>
header
element.
The title is marked up using a h2
element and the tagline is in a p
element. A sample CSS styled rendering of the
title and tagline is provided below the code example.
<header> <h2>3D films set for popularity slide </h2> <p>First drop in 3D box office projected for this year despite hotly tipped summer blockbusters, according to Fitch Ratings report</p> </header>
header
element.
The title is marked up using a h1
element and the taglines are each in a p
element. A sample CSS styled rendering of the
title and taglines is provided below the code example.
<header> <p>Magazine of the Decade</p> <h1>THE MONTH</h1> <p>The Best of UK and Foreign Media</p> </header>
4.13.2. Bread crumb navigation
This specification does not provide a machine-readable way of describing bread-crumb navigation
menus. Authors are encouraged to markup bread-crumb navigation as a list. The nav
element can be used to mark the
list containing links as being a navigation block.
<nav> <h2>You are here:</h2> <ul id="navlist"> <li><a href="/">Main</a> →</li> <li><a href="/products/">Products</a> →</li> <li><a href="/products/dishwashers/">Dishwashers</a> →</li> <li><a>Second hand</a></li> </ul> </nav>
The breadcrumb code example could be styled as a horizonatal list using CSS:
The use of the right angle bracket symbol ">" to indicate path direction is discouraged as its meaning, in the context used, is not clearly conveyed to all users.
4.13.3. Tag clouds
This specification does not define any markup specifically for marking up lists
of keywords that apply to a group of pages (also known as tag clouds). In general, authors
are encouraged to either mark up such lists using ul
elements with explicit inline
counts that are then hidden and turned into a presentational effect using a style sheet, or to use
SVG.
<style> @media screen, print, handheld, tv { /* should be ignored by non-visual browsers */ .tag-cloud > li > span { display: none; } .tag-cloud > li { display: inline; } .tag-cloud-1 { font-size: 0.7em; } .tag-cloud-2 { font-size: 0.9em; } .tag-cloud-3 { font-size: 1.1em; } .tag-cloud-4 { font-size: 1.3em; } .tag-cloud-5 { font-size: 1.5em; } } </style> ... <ul class="tag-cloud"> <li class="tag-cloud-4"><a title="28 instances" href="/t/apple">apple</a> <span>(popular)</span> <li class="tag-cloud-2"><a title="6 instances" href="/t/kiwi">kiwi</a> <span>(rare)</span> <li class="tag-cloud-5"><a title="41 instances" href="/t/pear">pear</a> <span>(very popular)</span> </ul>
The actual frequency of each tag is given using the title
attribute. A CSS style sheet is provided to convert the markup into a cloud of differently-sized
words, but for user agents that do not support CSS or are not visual, the markup contains
annotations like "(popular)" or "(rare)" to categorize the various tags by frequency, thus
enabling all users to benefit from the information.
The ul
element is used (rather than ol
) because the order is not
particularly important: while the list is in fact ordered alphabetically, it would convey the
same information if ordered by, say, the length of the tag.
The tag
rel
-keyword is not used on these a
elements because they do not represent tags that apply
to the page itself; they are just part of an index listing the tags themselves.
4.13.4. Conversations
This specification does not define a specific element for marking up conversations, meeting minutes, chat transcripts, dialogs in screenplays, instant message logs, and other situations where different players take turns in discourse.
Instead, authors are encouraged to mark up conversations using p
elements and
punctuation. Authors who need to mark the speaker for styling purposes are encouraged to use span
or b
. Paragraphs with their text wrapped in the i
element can be used for marking up stage directions.
<p> Costello: Look, you gotta first baseman? <p> Abbott: Certainly. <p> Costello: Who’s playing first? <p> Abbott: That’s right. <p> Costello becomes exasperated. <p> Costello: When you pay off the first baseman every month, who gets the money? <p> Abbott: Every dollar of it.
data
element to provide Unix timestamps for each line. Note that the timestamps are
provided in a format that the time
element does not support, so the data
element is used instead (namely, Unix time_t
timestamps).
Had the author wished to mark up the data using one of the date and time formats supported by the time
element, that element could have been used instead of data
. This
could be advantageous as it would allow data analysis tools to detect the timestamps
unambiguously, without coordination with the page author.
<p> <data value="1319898155">14:22</data> <b>egof</b> I’m not that nerdy, I’ve only seen 30% of the star trek episodes <p> <data value="1319898192">14:23</data> <b>kaj</b> if you know what percentage of the star trek episodes you have seen, you are inarguably nerdy <p> <data value="1319898200">14:23</data> <b>egof</b> it’s unarguably <p> <data value="1319898228">14:23</data> <i>* kaj blinks</i> <p> <data value="1319898260">14:24</data> <b>kaj</b> you are not helping your case
dl
elements to list the possible responses at each point in the conversation.
Another option to consider is describing the conversation in the form of a DOT file, and
outputting the result as an SVG image to place in the document. [DOT]
<p> Next, you meet a fisherman. You can say one of several greetings: <dl> <dt> "Hello there!" <dd> <p> He responds with "Hello, how may I help you?"; you can respond with: <dl> <dt> "I would like to buy a fish." <dd> <p> He sells you a fish and the conversation finishes. <dt> "Can I borrow your boat?" <dd> <p> He is surprised and asks "What are you offering in return?". <dl> <dt> "Five gold." (if you have enough) <dt> "Ten gold." (if you have enough) <dt> "Fifteen gold." (if you have enough) <dd> <p> He lends you the boat. The conversation ends. <dt> "A fish." (if you have one) <dt> "A newspaper." (if you have one) <dt> "A pebble." (if you have one) <dd> <p> "No thanks", he replies. Your conversation options at this point are the same as they were after asking to borrow the boat, minus any options you’ve suggested before. </dl> </dd> </dl> </dd> <dt> "Vote for me in the next election!" <dd> <p> He turns away. The conversation finishes. <dt> "Sir, are you aware that your fish are running away?" <dd> <p> He looks at you skeptically and says "Fish cannot run, sir". <dl> <dt> "You got me!" <dd> <p> The fisherman sighs and the conversation ends. <dt> "Only kidding." <dd> <p> "Good one!" he retorts. Your conversation options at this point are the same as those following "Hello there!" above. <dt> "Oh, then what are they doing?" <dd> <p> He looks at his fish, giving you an opportunity to steal his boat, which you do. The conversation ends. </dl> </dd> </dl>
<section> <h1>Dialog</h1> <p><small>Some characters repeat their lines in order each time you interact with them, others randomly pick from amongst their lines. Those who respond in order have numbered entries in the lists below.</small> <h2>The Shopkeeper</h2> <ul> <li>How may I help you? <li>Fresh apples! <li>A loaf of bread for madam? </ul> <h2>The pilot</h2> <p>Before the accident: <ul> </li>I’m about to fly out, sorry! </li>Sorry, I’m just waiting for flight clearance and then I’ll be off! </ul> <p>After the accident: <ol> <li>I’m about to fly out, sorry! <li>Ok, I’m not leaving right now, my plane is being cleaned. <li>Ok, it’s not being cleaned, it needs a minor repair first. <li>Ok, ok, stop bothering me! Truth is, I had a crash. </ol> <h2>Clan Leader</h2> <p>During the first clan meeting: <ul> <li>Hey, have you seen my daughter? I bet she’s up to something nefarious again... <li>Nice weather we’re having today, eh? <li>The name is Bailey, Jeff Bailey. How can I help you today? <li>A glass of water? Fresh from the well! </ul> <p>After the earthquake: <ol> <li>Everyone is safe in the shelter, we just have to put out the fire! <li>I’ll go and tell the fire brigade, you keep hosing it down! </ol> </section>
4.13.5. Footnotes
HTML does not have a dedicated mechanism for marking up footnotes. Here are the suggested alternatives.
For short inline annotations, the title
attribute could be used.
title
attribute.
<p> <b>Customer</b>: Hello! I wish to register a complaint. Hello. Miss? <p> <b>Shopkeeper</b>: <span title="Colloquial pronunciation of 'What do you'" >Watcha</span> mean, miss? <p> <b>Customer</b>: Uh, I’m sorry, I have a cold. I wish to make a complaint. <p> <b>Shopkeeper</b>: Sorry, <span title="This is, of course, a lie.">we’re closing for lunch</span>.
Relying on the title
attribute for the visual display
of text content is currently discouraged as many user agents do not expose the attribute in an accessible manner
as required by this specification (e.g., requiring a pointing device such as a mouse to cause a tooltip to appear,
which excludes keyboard-only users and touch-only users, such as anyone with a modern phone or
tablet).
If the title
attribute is used, CSS can be used to
draw the reader’s attention to the elements with the attribute.
title
attribute.
[title] { border-bottom: thin dashed; }
For
annotations, the a
element should be used, pointing to
an element later in the document. The convention is that the
contents of the link be a number in square brackets.
<p> Announcer: Number 16: The <i>hand</i>. <p> Interviewer: Good evening. I have with me in the studio tonight Mr Norman St John Polevaulter, who for the past few years has been contradicting people. Mr Polevaulter, why <em>do</em> you contradict people? <p> Norman: I don’t. <sup><a href="#fn1" id="r1">[1]</a></sup> <p> Interviewer: You told me you did! ... <section> <p id="fn1"><a href="#r1">[1]</a> This is, naturally, a lie, but paradoxically if it were true he could not say so without contradicting the interviewer and thus making it false.</p> </section>
For side notes, longer annotations that apply to entire sections of the text rather than just
specific words or sentences, the aside
element should be used.
<p> <span class="speaker">Customer</span>: I will not buy this record, it is scratched. <p> <span class="speaker">Shopkeeper</span>: I’m sorry? <p> <span class="speaker">Customer</span>: I will not buy this record, it is scratched. <p> <span class="speaker">Shopkeeper</span>: No no no, this is a tobacconist’s. <aside role="note"> <p>In 1970, the British Empire lay in ruins, and foreign nationalists frequented the streets — many of them Hungarians (not the streets — the foreign nationals). Sadly, Alexander Yalt has been publishing incompetently-written phrase books. </aside>
In the example above an ARIA role="note"
, permitted for use on aside
,
has been added to override the default semantics of the aside
element, as the use of the
element in this context, more closely matches the note role.
For figures or tables, footnotes can be included in the relevant figcaption
or caption
element, or in surrounding prose.
figure
element is used to give a single legend to the combination of the table and
its footnotes.
<figure> <figcaption>Table 1. Alternative activities for knights.</figcaption> <table> <tr> <th> Activity <th> Location <th> Cost <tr> <td> Dance <td> Wherever possible <td> £0<sup><a href="#fn1">1</a></sup> <tr> <td> Routines, chorus scenes<sup><a href="#fn2">2</a></sup> <td> Undisclosed <td> Undisclosed <tr> <td> Dining<sup><a href="#fn3">3</a></sup> <td> Camelot <td> Cost of ham, jam, and spam<sup><a href="#fn4">4</a></sup> </table> <p id="fn1">1. Assumed.</p> <p id="fn2">2. Footwork impeccable.</p> <p id="fn3">3. Quality described as "well".</p> <p id="fn4">4. A lot.</p> </figure>
4.14. Disabled elements
An element is said to be actually disabled if it falls into one of the following categories:
- a
button
element that is disabled - an
input
element that is disabled - a
select
element that is disabled - a
textarea
element that is disabled - an
optgroup
element that has adisabled
attribute - an
option
element that is disabled - a
menuitem
element that has adisabled
attribute - a
fieldset
element that is a disabled fieldset
This definition is used to determine what elements can be focused and which elements match the :disabled
pseudo-class.
4.15. Matching HTML elements using selectors
4.15.1. Case-sensitivity
The Selectors specification leaves the case-sensitivity of element names, attribute names, and attribute values to be defined by the host language. [CSS3-SELECTORS]
Selectors defines that ID and class selectors, when matched against elements in documents that are in quirks mode, will be matched in an ASCII case-insensitive manner.
When comparing a CSS element type selector to the names of html elements in HTML documents, the CSS element type selector must first be converted to ASCII lowercase. The same selector when compared to other elements must be compared according to its original case. In both cases, the comparison is case-sensitive.
When comparing the name part of a CSS attribute selector to the names of namespace-less attributes on html elements in HTML documents, the name part of the CSS attribute selector must first be converted to ASCII lowercase. The same selector when compared to other attributes must be compared according to its original case. In both cases, the comparison is case-sensitive.
Attribute selectors on an HTML element in an HTML document must treat the values of attributes with the following names as ASCII case-insensitive, with one exception as noted in §10 Rendering:
accept
accept-charset
align
alink
axis
bgcolor
charset
checked
clear
codetype
color
compact
declare
defer
dir
direction
disabled
enctype
face
frame
hreflang
http-equiv
lang
language
link
media
method
multiple
nohref
noresize
noshade
nowrap
readonly
rel
rev
rules
scope
scrolling
selected
shape
target
text
type
(except as specified in §10 Rendering)valign
valuetype
vlink
All other attribute values and everything else must be treated as entirely case-sensitive for the purposes of selector matching. This includes:
- IDs and classes in no-quirks mode and limited-quirks mode
- the names of elements not in the HTML namespace
- the names of html elements in XML documents
- the names of attributes of elements not in the HTML namespace
- the names of attributes of html elements in XML documents
- the names of attributes that themselves have namespaces
4.15.2. Pseudo-classes
There is only one known native implementation of :dir(ltr)
pseudo-class matching (Firefox/Gecko). Therefore this feature should not be relied upon.
There are a number of dynamic selectors that can be used with HTML. This section defines when these selectors match HTML elements. [CSS3-SELECTORS] [CSS-UI-3]
:link
:visited
-
All
a
elements that have anhref
attribute, allarea
elements that have anhref
attribute, and alllink
elements that have anhref
attribute, must match one of:link
and:visited
.Other specifications might apply more specific rules regarding how these elements are to match these pseudo-classes, to mitigate some privacy concerns that apply with straightforward implementations of this requirement.
:active
-
The
:active
pseudo-class is defined to match an elementwhile an element is being activated by the user
.To determine whether a particular element is being activated for the purposes of defining the
:active
pseudo-class only, an HTML user agent must use the first relevant entry in the following list.- If the element has a descendant that is currently matching the
:active
pseudo-class - The element is being activated.
- If the element is the labeled control of a
label
element that is currently matching :active - The element is being activated.
- If the element is a
button
element- If the element is an
input
element whosetype
attribute is in the submit button, image button, Reset Button, or Button state - If the element is an
-
The element is being activated if it is in a formal activation state and it is not disabled.
For example, if the user is using a keyboard to push a
button
element by pressing the space bar, the element would match this pseudo-class in between the time that the element received thekeydown
event and the time the element received thekeyup
event. - If the element is a
menuitem
element - The element is being activated if it is in a formal activation state and it does not have a
disabled
attribute. - If the element is an
a
element that has anhref
attribute- If the element is an
area
element that has anhref
attribute- If the element is a
link
element that has anhref
attribute- If the element has its tabindex focus flag set
- If the element is an
- The element is being activated if it is in a formal activation state.
- If the element is being actively pointed at
- The element is being activated.
An element is said to be in a formal activation state between the time the user begins to indicate an intent to trigger the element’s activation behavior and either the time the user stops indicating an intent to trigger the element’s activation behavior, or the time the element’s activation behavior has finished running, which ever comes first.
An element is said to be being actively pointed at while the user indicates the element using a pointing device while that pointing device is in the "down" state (e.g., for a mouse, between the time the mouse button is pressed and the time it is depressed; for a finger in a multitouch environment, while the finger is touching the display surface).
- If the element has a descendant that is currently matching the
:hover
-
The
:hover
pseudo-class is defined to match an elementwhile the user designates an element with a pointing device
. For the purposes of defining the:hover
pseudo-class only, an HTML user agent must consider an element as being one that the user designates if it is:-
An element that the user indicates using a pointing device.
-
An element that has a descendant that the user indicates using a pointing device.
-
An element that is the labeled control of a
label
element that is currently matching :hover.
Consider in particular a fragment such as:<p> <label for=c> <input id=a> </label> <span id=b> <input id=c> </span> </p>
If the user designates the element with ID "
a
" with their pointing device, then thep
element (and all its ancestors not shown in the snippet above), thelabel
element, the element with ID "a
", and the element with ID "c
" will match the :hover pseudo-class. The element with ID "a
" matches it from condition 1, thelabel
andp
elements match it because of condition 2 (one of their descendants is designated), and the element with ID "c
" matches it through condition 3 (itslabel
element matches :hover). However, the element with ID "b
" does not match :hover: its descendant is not designated, even though it matches :hover. -
:focus
-
For the purposes of the CSS ':focus' pseudo-class, an element has the focus when its top-level browsing context has the system focus, it is not itself a browsing context container, and it is one of the elements listed in the focus chain of the currently focused area of the top-level browsing context.
:enabled
-
The
:enabled
pseudo-class must match any element that is one of the following:- a
button
element that is not disabled - an
input
element that is not disabled - a
select
element that is not disabled - a
textarea
element that is not disabled - an
optgroup
element that does not have adisabled
attribute - an
option
element that is not disabled - a
menuitem
element that does not have adisabled
attribute - a
fieldset
element that is not a disabled fieldset
- a
:disabled
-
The
:disabled
pseudo-class must match any element that is actually disabled. :checked
-
The
:checked
pseudo-class must match any element falling into one of the following categories:input
elements whosetype
attribute is in the Checkbox state and whose checkedness state is trueinput
elements whosetype
attribute is in the Radio Button state and whose checkedness state is trueoption
elements whose selectedness is truemenuitem
elements whosetype
attribute is in the Checkbox state and that have achecked
attributemenuitem
elements whosetype
attribute is in the Radio state and that have achecked
attribute
:indeterminate
-
The
:indeterminate
pseudo-class must match any element falling into one of the following categories:input
elements whosetype
attribute is in the Checkbox state and whoseindeterminate
IDL attribute is set to trueinput
elements whosetype
attribute is in the Radio Button state and whose radio button group contains noinput
elements whose checkedness state is true.progress
elements with novalue
content attribute
:default
-
The
:default
pseudo-class must match any element falling into one of the following categories:button
elements that are their form’s default buttoninput
elements whosetype
attribute is in the submit button or image button state, and that are their form’s default buttoninput
elements to which thechecked
attribute applies and that have achecked
attributeoption
elements that have aselected
attribute
:valid
-
The
:valid
pseudo-class must match any element falling into one of the following categories:- elements that are candidates for constraint validation and that satisfy their constraints
form
elements that are not the form owner of any elements that themselves are candidates for constraint validation but do not satisfy their constraintsfieldset
elements that have no descendant elements that themselves are candidates for constraint validation but do not satisfy their constraints
:invalid
-
The
:invalid
pseudo-class must match any element falling into one of the following categories:- elements that are candidates for constraint validation but that do not satisfy their constraints
form
elements that are the form owner of one or more elements that themselves are candidates for constraint validation but do not satisfy their constraintsfieldset
elements that have of one or more descendant elements that themselves are candidates for constraint validation but do not satisfy their constraints
:in-range
-
The
:in-range
pseudo-class must match all elements that are candidates for constraint validation, have range limitations, and that are neither suffering from an underflow nor suffering from an overflow. :out-of-range
-
The
:out-of-range
pseudo-class must match all elements that are candidates for constraint validation, have range limitations, and that are either suffering from an underflow or suffering from an overflow. :required
-
The
:required
pseudo-class must match any element falling into one of the following categories: :optional
-
The
:optional
pseudo-class must match any element falling into one of the following categories: :read-only
:read-write
-
The
:read-write
pseudo-class must match any element falling into one of the following categories, which for the purposes of Selectors are thus considered user-alterable: [CSS3-SELECTORS]input
elements to which thereadonly
attribute applies, and that are mutable (i.e., that do not have thereadonly
attribute specified and that are not disabled)textarea
elements that do not have areadonly
attribute, and that are not disabled- elements that are editing hosts or editable and are neither
input
elements nortextarea
elements
The
:read-only
pseudo-class must match all other html elements. :dir(ltr)
-
The
:dir(ltr)
pseudo-class must match all elements whose directionality is 'ltr'. :dir(rtl)
-
The
:dir(rtl)
pseudo-class must match all elements whose directionality is 'rtl'.
Another section of this specification defines the target element used with the :target
pseudo-class.
This specification does not define when an element matches the :lang()
dynamic
pseudo-class, as it is defined in sufficient detail in a language-agnostic fashion in the
Selectors specification. [CSS3-SELECTORS]
5. User interaction
5.1. The hidden
attribute
All html elements may have the hidden
content attribute set. The hidden
attribute is a boolean attribute. When specified on an element, it
indicates that the element is not yet, or is no longer, directly relevant to the page’s current
state, or that it is being used to declare content to be reused by other parts of the page as
opposed to being directly accessed by the user. User agents should not render
elements that have the hidden
attribute specified. This requirement may be
implemented indirectly through the style layer. For example, an HTML+CSS user agent could
implement these requirements using the rules suggested in §10 Rendering.
Because this attribute is typically implemented using CSS, it’s also possible to override it
using CSS. For instance, a rule that applies 'display: block' to all elements will cancel the
effects of the hidden
attribute. Authors therefore have to take care when writing
their style sheets to make sure that the attribute is still styled as expected.
<h1>The Example Game</h1> <section> <h2>Login</h2> <form> ... <!-- calls login() once the user’s credentials have been checked --> </form> <script> function login() { // switch screens document.getElementById('login').hidden = true; document.getElementById('game').hidden = false; } </script> </section> <section hidden> ... </section>
The hidden
attribute must not be used to hide content just from one presentation —
if something is marked hidden
, it is hidden from all presentations, including, for instance, screen readers.
Elements that are not themselves hidden
must not hyperlink to elements that are hidden
. The for
attributes of label
and output
elements that are not
themselves hidden
must similarly not refer to elements that are hidden
. In both cases, such references would cause user confusion.
Elements and scripts may, however, refer to elements that are hidden
in other contexts.
href
attribute to link to a
section marked with the hidden
attribute. If the content is not applicable or relevant, then there
is no reason to link to it.
It would be fine, however, to use the ARIA aria-describedby
attribute to
refer to descriptions that are themselves hidden
. While hiding the descriptions
implies that they are not useful alone, they could be written in
such a way that they are useful in the specific context of being
referenced from the images that they describe.
Similarly, a canvas
element with the hidden
attribute could be used by a
scripted graphics engine as an off-screen buffer, and a form
control could refer to a hidden form
element using its form
attribute.
Accessibility APIs are encouraged to provide a way to expose structured content while marking it as hidden in the default view. Such content should not be perceivable to users in the normal document flow in any modality, whether using Assistive Technology (AT) or mainstream User Agents.
When such features are available, User Agents may use them to
expose the full semantics of hidden
elements to AT when appropriate, if such content is referenced
indirectly by an ID reference or valid hash-name reference. This allows ATs to access the
structure of these hidden
elements
upon user request, while keeping the content hidden in all
presentations of the normal document flow. Authors who wish to prevent
user-initiated viewing of a hidden
element should not reference the element with such a mechanism.
Because some User Agents have flattened hidden content when
exposing such content to AT, authors should not reference hidden
content which would lose essential
meaning when flattened.
href
attribute to link to a section marked with the hidden
attribute.
If the content is not applicable or relevant, then there is no reason to link to it.
It would be fine, however, to use the ARIA aria-describedby
attribute to refer to descriptions that are
themselves hidden
. While hiding the descriptions implies that
they are not useful alone, they could be written in such a way that they are useful in the
specific context of being referenced from the images that they describe.
Similarly, a canvas
element with the hidden
attribute could be used by a scripted graphics engine as an off-screen buffer, and a form control
could refer to a hidden form
element using its form
attribute.
Elements in a section hidden by the hidden
attribute are still
active, e.g., scripts and form controls in such sections still execute and submit respectively.
Only their presentation to the user changes.
5.2. Inert subtrees
This section does not define or create any content attribute named "inert". This section merely defines an abstract concept of inertness.
A node (in particular elements and text nodes) can be marked as inert. When a node is inert, then the user agent must act as if the node was absent for the purposes of targeting user interaction events, may ignore the node for the purposes of text search user interfaces (commonly known as "find in page"), and may prevent the user from selecting text in that node. User agents should allow the user to override the restrictions on search and text selection, however.
For example, consider a page that consists of just a single inert paragraph positioned in the middle of a body
. If a user moves their pointing device
from the body
over to the inert paragraph and clicks on the paragraph,
no mouseover
event would be fired, and the mousemove
and click
events would
be fired on the body
element rather than the paragraph.
When a node is inert, it generally cannot be focused. Inert nodes that are commands will also get disabled.
While a browsing context container is marked as inert, its nested browsing context’s active document, and all nodes in that Document
, must be marked as inert.
An entire Document
can be marked as blocked by a modal dialog subject. While a Document
is so marked, every node that is in the Document
, with the exception of the subject element and its
descendants, must be marked inert. (The elements excepted by this paragraph can
additionally be marked inert through other means; being part of a modal dialog does not
"protect" a node from being marked inert.)
Only one element at a time can mark a Document
as being blocked by a modal
dialog.
5.3. Activation
Certain elements in HTML have an activation behavior, which means that the user
can activate them. This triggers a sequence of events dependent on the activation mechanism, and
normally culminating in a click
event, as described below.
The user agent should allow the user to manually trigger elements that have an activation behavior, for instance using keyboard or voice input, or through mouse clicks. When the user triggers an element with a defined activation behavior in a manner other than clicking it, the default action of the interaction event must be to run synthetic click activation steps on the element.
Each element has a click in progress flag, initially set to false.
When a user agent is to run synthetic click activation steps on an element, the user agent must run the following steps:
- If the element’s click in progress flag is set to true, then abort these steps.
- Set the click in progress flag on the element to true.
- Run pre-click activation steps on the element.
- Fire a
click
event at the element. If the run synthetic click activation steps algorithm was invoked because theclick()
method was invoked, then theisTrusted
attribute must be initialized to false. -
If this
click
event is not canceled, run post-click activation steps on the element.If the event is canceled, the user agent must run canceled activation steps on the element instead.
- Set the click in progress flag on the element to false.
When a pointing device is clicked, the user agent must run authentic click activation
steps instead of firing the click
event. When a user agent is to run authentic click activation steps for a given event event, it must
follow these steps:
- Let target be the element designated by the user (the target of event).
- If target is a
canvas
element, run the canvasMouseEvent
rerouting steps. If this changes event’s target, then let target be the new target. - Set the click in progress flag on target to true.
- Let e be the nearest activatable element of target (defined below), if any.
- If there is an element e, run pre-click activation steps on it.
-
Dispatch event (the required
click
event) at target.If there is an element e and the
click
event is not canceled, run post-click activation steps on element e.If there is an element e and the event is canceled, run canceled activation steps on element e.
- Set the click in progress flag on target to false.
The algorithms above don’t run for arbitrary synthetic events dispatched by author script. The click()
method can be used to make the run synthetic click activation steps algorithm happen programmatically.
Click-focusing behavior (e.g., the focusing of a text field when user clicks in one) typically happens before the click, when the mouse button is first depressed, and is therefore not discussed here.
Given an element target, the nearest activatable element is the element returned by the following algorithm:
- If target has a defined activation behavior, then return target and abort these steps.
- If target has a parent element, then set target to that parent element and return to the first step.
- Otherwise, there is no nearest activatable element.
When a user agent is to run pre-click activation steps on an element, it must run the pre-click activation steps defined for that element, if any.
When a user agent is to run canceled activation steps on an element, it must run the canceled activation steps defined for that element, if any.
When a user agent is to run post-click activation steps on an element, it must run
the activation behavior defined for that element, if any. Activation behaviors can
refer to the click
event that was fired by the steps above
leading up to this point.
- element .
click
() - Acts as if the element was clicked.
click()
method must run the following steps:
-
If the element is a form control that is disabled, abort these steps.
-
Run synthetic click activation steps on the element.
5.4. Focus
5.4.1. Introduction
This section is non-normative.
An HTML user interface typically consists of multiple interactive widgets, such as form controls, scrollable regions, links, dialog boxes, browser tabs, and so forth. These widgets form a hierarchy, with some (e.g., browser tabs) containing others (e.g., links, form controls).
When interacting with an interface using a keyboard, key input is channeled from the system, through the hierarchy of interactive widgets, to an active widget, which is said to be focused.
The hierarchy of focusable widgets, in this scenario, would include the browser window, which would have, amongst its children, the browser tab containing the HTML application. The tab itself would have as its children the various links and text fields, as well as the dialog. The dialog itself would have as its children the text field and the button.
If the widget with focus in this example was the text field in the dialog box, then key input would be channeled from the graphical system to ① the Web browser, then to ② the tab, then to ③ the dialog, and finally to ④ the text field.
Keyboard events are always targeted at this focused element.
5.4.2. Data model
The term focusable area is used to refer to regions of the interface that can become the target of keyboard input. Focusable areas can be elements, parts of elements, or other regions managed by the user agent.
Each focusable area has a DOM anchor, which is a Node
object
that represents the position of the focusable area in the DOM. (When the focusable
area is itself a Node
, it is its own DOM anchor.) The DOM anchor is
used in some APIs as a substitute for the focusable area when there is no other DOM object
to represent the focusable area.
The following table describes what objects can be focusable areas. The cells in the left column describe objects that can be focusable areas; the cells in the right column describe the DOM anchors for those elements. (The cells that span both columns are non-normative examples.)
Focusable area | DOM anchor |
---|---|
Examples | |
Elements that have their tabindex focus flag set, that are not actually disabled, that are not expressly inert, and that are either being rendered or being used as relevant canvas fallback content. | The element itself. |
| |
The shapes of area elements in an image map associated with an img element that is being rendered and is not expressly inert.
| The img element.
|
In the following example, the
area element creates two shapes, one on each
image. The DOM anchor of the first shape is the first img element, and the DOM anchor of the second shape is the second img element.
<map id=wallmap><area alt="Enter Door" coords="10,10,100,200" href="door.html"></map> ... <img src="images/innerwall.jpeg" alt="There is a white wall here, with a door." usemap="#wallmap"> ... <img src="images/outerwall.jpeg" alt="There is a red wall here, with a door." usemap="#wallmap"> | |
The user-agent provided subwidgets of elements that are being rendered and are not actually disabled or expressly inert. | The element for which the focusable area is a subwidget. |
The controls in the user
interface that is exposed to the user for a | |
The scrollable regions of elements that are being rendered and are not expressly inert. | The element for which the box that the scrollable region scrolls was created. |
The CSS overflow property’s scroll value typically creates a scrollable region. | |
The viewport of a Document that is in a browsing context and is not inert.
| The Document for which the viewport was created.
|
The contents of an | |
Any other element or part of an element, especially to aid with accessibility or to better match platform conventions. | The element. |
A user agent could make all list item bullets focusable, so that a user can more easily navigate lists. Similarly, a user agent could make all elements with |
A browsing context container (e.g., an iframe
) is a focusable area, but key events routed to a browsing context
container get immediately routed to the nested browsing context’s active
document. Similarly, in sequential focus navigation a browsing context
container essentially acts merely as a placeholder for its nested browsing context’s active document.
Each focusable area belongs to a control group. Each control group has an owner. Control group owners are control group owner objects. The following are control group owner objects:
Document
object that have browsing contexts.
Each control group owner object owns one control group (though that group might be empty).
If the DOM anchor of a focusable area is a control group owner object, then that focusable area belongs to that control group owner object’s control group. Otherwise, the focusable area belongs to its DOM anchor’s nearest ancestor control group owner object.
Document
for which the viewport was created, an input
control belongs to the control
group of its nearest ancestor Document
, and an image
map’s shapes belong to the nearest ancestor Document
of the img
elements (not the area
elements — this means one area
element might create multiple shapes in different control groups). An element is expressly inert if it is inert but it is not a control group owner object and its nearest ancestor control group owner object is not inert.
One focusable area in each non-empty control group is designated the focused area of the control group. Which control is so designated changes over time, based on algorithms in this specification. If a control group is empty, it has no focused area.
Focusable areas in control groups are ordered relative to the tree order of their DOM anchors. Focusable areas with the same DOM anchor in a control group are ordered relative to their CSS box’s relative positions in a pre-order, depth-first traversal of the box tree. [CSS-2015]
The currently focused area of a top-level browsing context at any particular time is the focusable area returned by this algorithm:
- Let candidate be the
Document
of the top-level browsing context. -
If candidate has a non-empty control group, and the designated focused area of the control group is a browsing context container, then let candidate be the active document of that browsing context container’s nested browsing context, and redo this step.
Otherwise, if candidate has a non-empty control group, let candidate be the designated focused area of the control group.
- Return candidate.
An element that is the DOM anchor of a focusable area is said to gain focus when that focusable area becomes the currently focused area of a top-level browsing context. When an element is the DOM anchor of a focusable area of the currently focused area of a top-level browsing context, it is focused.
- Let current object be subject.
- Let output be an empty list.
- Loop: Append current object to output.
-
If current object is an
area
element’s shape, append thatarea
element to output.Otherwise, if current object is a focusable area whose DOM anchor is an element that is not current object itself, append that DOM anchor element to output.
-
If current object is a focusable area, let current object be that focusable area’s control group’s owner, and return to the step labeled loop.
Otherwise, if current object is a
Document
in a nested browsing context, let current object be its browsing context container, and return to the step labeled loop. -
Return output.
The chain starts with subject and (if subject is or can be the currently focused area of a top-level browsing context) continues up the focus hierarchy up to the
Document
of the top-level browsing context.
5.4.3. The tabindex
attribute
The tabindex
content attribute allows authors to
indicate that an element is supposed to be focusable, and
whether it is supposed to be reachable using sequential focus navigation and, if so,
what is to be the relative order of the element for the purposes of sequential focus navigation.
The name "tab index" comes from the common use of the "tab" key to navigate through the focusable
elements. The term "tabbing" refers to moving forward through the focusable elements that can be
reached using sequential focus navigation.
When the attribute is omitted, the user agent applies defaults. (There is no way to make an element that is being rendered be not focusable at all without disabling it or making it inert.)
The tabindex
attribute, if specified, must have a value
that is a valid integer. Positive numbers specify the relative position of the
element’s focusable areas in the sequential focus
navigation order, and negative numbers indicate that the control is to be unreachable by sequential focus navigation.
Each element can have a tabindex focus flag set, as defined below. This flag is a factor that contributes towards determining whether an element is a focusable area, as described in the previous section.
If the tabindex
attribute is specified on an element, it
must be parsed using the rules for parsing integers. The attribute’s values, or lack
thereof, must be interpreted as follows:
- If the attribute is omitted or parsing the value returns an error
-
The user agent should follow platform conventions to determine if the element’s tabindex focus flag is set and, if so, whether the element and any focusable areas that have the element as their DOM anchor can be reached using sequential focus navigation, and if so, what their relative position in the sequential focus navigation order is to be.
Modulo platform conventions, it is suggested that for the following elements, the tabindex focus flag be set:
a
elements that have anhref
attributelink
elements that have anhref
attributebutton
elementsinput
elements whosetype
attribute are not in the stateselect
elementstextarea
elementsmenuitem
elements- Elements with a
draggable
attribute set, if that would enable the user agent to allow the user to begin a drag operations for those elements without the use of a pointing device - Editing hosts
- Browsing context containers
One valid reason to ignore the platform conventions and always allow an element to be focused (by setting its tabindex focus flag) would be if the user’s only mechanism for activating an element is through a keyboard action that triggers the focused element.
- If the value is a negative integer
-
The user agent must set the element’s tabindex focus flag, but should omit the element from the sequential focus navigation order.
One valid reason to ignore the requirement that sequential focus navigation not allow the author to lead to the element would be if the user’s only mechanism for moving the focus is sequential focus navigation. For instance, a keyboard-only user would be unable to click on a text field with a negative
tabindex
, so that user’s user agent would be well justified in allowing the user to tab to the control regardless. - If the value is a zero
-
The user agent must set the element’s tabindex focus flag, should allow the element and any focusable areas that have the element as their DOM anchor to be reached using sequential focus navigation, following platform conventions to determine the element’s relative position in the sequential focus navigation order.
- If the value is greater than zero
-
The user agent must set the element’s tabindex focus flag, should allow the element and any focusable areas that have the element as their DOM anchor to be reached using sequential focus navigation, and should place the element — referenced as candidate below — and the aforementioned focusable areas in the sequential focus navigation order so that, relative to other focusable areas in the sequential focus navigation order, they are:
- before any focusable area whose DOM anchor is an element whose
tabindex
attribute has been omitted or whose value, when parsed, returns an error, - before any focusable area whose DOM anchor is an element whose
tabindex
attribute has a value equal to or less than zero, - after any focusable area whose DOM anchor is an element whose
tabindex
attribute has a value greater than zero but less than the value of thetabindex
attribute on candidate, - after any focusable area whose DOM anchor is an element whose
tabindex
attribute has a value equal to the value of thetabindex
attribute on candidate but that is earlier in the document in tree order than candidate, - before any focusable area whose DOM anchor is an element whose
tabindex
attribute has a value equal to the value of thetabindex
attribute on candidate but that is later in the document in tree order than candidate, and - before any focusable area whose DOM anchor is an element whose
tabindex
attribute has a value greater than the value of thetabindex
attribute on candidate.
- before any focusable area whose DOM anchor is an element whose
An element that has its tabindex focus flag set but does not otherwise have an activation behavior defined has an activation behavior that does nothing.
This means that an element that is only focusable because of its tabindex
attribute will fire a click
event in response to a non-mouse activation (e.g., hitting the
"enter" key while the element is focused).
An element with the tabindex
attribute specified is interactive content.
The tabIndex
IDL attribute must reflect the value of the tabindex
content
attribute. Its default value is 0 for elements that are focusable and -1 for elements that
are not focusable.
Most current browsers instead give the tabIndex
IDL attribute a value of 0 for some list of elements that are by default a focusable area, and -1 for other elements, if there is no tabindex
content attribute set. This behaviour is not well-defined and will hopefully be improved in the future.
5.4.4. Processing model
The focusing steps for an object new focus target that is either a focusable area, or an element that is not a focusable area, or a browsing context, are as follows. They can optionally be run with a fallback target.
-
If new focus target is not a focusable area, then run the first matching set of steps from the following list:
- If new focus target is an
area
element with one or more shapes that are focusable areas -
Let new focus target be the shape corresponding to the first
img
element in tree order that uses the image map to which thearea
element belongs. - If new focus target is an element with one or more scrollable regions that are focusable areas
-
Let new focus target be the element’s first scrollable region, according to a pre-order, depth-first traversal of the box tree. [CSS-2015]
- If new focus target is the root element of its
Document
-
Let new focus target be the
Document
’s viewport. - If new focus target is a browsing context
-
Let new focus target be the browsing context’s active document.
- If new focus target is a browsing context container
-
Let new focus target be the browsing context container’s nested browsing context’s active document.
- Otherwise
-
If no fallback target was specified, abort the focusing steps.
Otherwise, let new focus target be the fallback target.
- If new focus target is an
-
If new focus target is a control group owner object that is not a focusable area, and its control group is not empty, then designate new focus target as the focused area of the control group, and redo this step.
Otherwise, if new focus target is a browsing context container, then let new focus target be the nested browsing context’s active document, and redo this step.
- If new focus target is a focusable area and its DOM anchor is inert, then abort these steps.
- If new focus target is the currently focused area of a top-level browsing context, then abort these steps.
- Let old chain be the focus chain of the currently focused area of the top-level browsing context in which new focus target finds itself.
- Let new chain be the focus chain of new focus target.
- Run the focus update steps with old chain, new chain, and new focus target respectively.
User agents must immediately run the focusing steps for a focusable area, or browsing context candidate whenever the user attempts to move the focus to candidate.
The unfocusing steps for an object old focus target that is either a focusable area or an element that is not a focusable area are as follows:
- If old focus target is inert, then abort these steps.
-
If old focus target is an
area
element and one of its shapes is the currently focused area of a top-level browsing context, or, if old focus target is an element with one or more scrollable regions, and one of them is the currently focused area of a top-level browsing context, then let old focus target be that currently focused area of a top-level browsing context. - Let old chain be the focus chain of the currently focused area of a top-level browsing context.
- If old focus target is not one of the entries in old chain, then abort these steps.
-
If old focus target is a focusable area, then let new focus target be the first focusable area of its control group (if the control group owner is a
Document
, this will always be a viewport).Otherwise, let new focus target be null.
- If new focus target is not null, then run the focusing steps for new focus target.
When the currently focused area of a top-level browsing context is somehow unfocused without another element being explicitly focused in its stead, the user agent must immediately run the unfocusing steps for that object.
The unfocusing steps do not always result in the focus changing, even when applied to the currently focused area of a top-level browsing context. For example, if the currently focused area of a top-level browsing context is a viewport, then it will usually keep its focus regardless until another focusable area is explicitly focused with the focusing steps.
When a focusable area is added to an empty control group, it must be designated the focused area of the control group.
Focus fixup rule one: When the designated focused area of a control group is removed from that control group in some way (e.g., it stops being a focusable area, it is removed from the DOM, it becomes expressly inert, etc), and the control group is still not empty: designate the first non-inert focused area in that control group to be the new focused area of the control group, if any; if they are all inert, then designate the first focused area in that control group to be the new focused area of the control group regardless of inertness. If such a removal instead results in the control group being empty, then there is simply no longer a focused area of the control group.
For example, this might happen because an element is removed from its Document
, or has a hidden
attribute added. It might
also happen to an input
element when the element gets disabled.
When the currently focused area of a top-level browsing context was a focusable area but stops being a focusable area, or when it starts being inert, the user agent must run the following steps:
- Let old focus target be whatever the currently focused area of the top-level browsing context was immediately before this algorithm became applicable (e.g., before the element was disabled, or the dialog was closed, or whatever caused this algorithm to run).
- Let old chain be the focus chain of the currently focused area of the top-level browsing context at the same time.
- Make sure that the changes implied by the focus fixup rules one, two, and three above are applied.
- Let new focus target be the currently focused area of a top-level browsing context.
- If old focus target and new focus target are the same, abort these steps.
- Let new chain be the focus chain of new focus target.
- Run the focus update steps with old chain, new chain, and new focus target respectively.
The focus update steps, given an old chain, a new chain, and a new focus target respectively, are as follows:
- Unset the sequential focus navigation starting point.
- If the last entry in old chain and the last entry in new chain are the same, pop the last entry from old chain and the last entry from new chain and redo this step.
-
For each entry entry in old chain, in order, run these substeps:
- If entry is an
input
element, and thechange
event applies to the element, and the element does not have a defined activation behavior, and the user has changed the element’s value or its list of selected files while the control was focused without committing that change, then fire a simple event that bubbles namedchange
at the element. -
If entry is an element, let blur event target be entry.
If entry is a
Document
object, let blur event target be thatDocument
object’sWindow
object.Otherwise, let blur event target be null.
- If entry is the last entry in old chain, and entry is an
Element
, and the last entry in new chain is also anElement
, then let related blur target be the last entry in new chain. Otherwise, let related blur target be null. -
If blur event target is not null, fire a focus event named
blur
at blur event target, with related blur target as the related target.In some cases, e.g., if entry is an
area
element’s shape, a scrollable region, or a viewport, no event is fired.
- If entry is an
- Apply any relevant platform-specific conventions for focusing new focus target. (For example, some platforms select the contents of a text field when that field is focused.)
-
For each entry entry in new chain, in reverse order, run these substeps:
-
If entry is a focusable area: Designate entry as the focused area of the control group.
-
If entry is an element, let focus event target be entry.
If entry is a
Document
object, let focus event target be thatDocument
object’sWindow
object.Otherwise, let focus event target be null.
- If entry is the last entry in new chain, and entry is an
Element
, and the last entry in old chain is also anElement
, then let related focus target be the last entry in old chain. Otherwise, let related focus target be null. -
If focus event target is not null, fire a focus event named
focus
at focus event target, with related focus target as the related target.In some cases, e.g., if entry is an
area
element’s shape, a scrollable region, or a viewport, no event is fired.
-
When a user agent is required to fire a focus event named e at
an element t and with a given related target r, the user
agent must create a trusted FocusEvent
object, initialize it to have the given name e, to not bubble, to not be
cancelable, and to have the relatedTarget
attribute initialized to r, the view
attribute initialized to the Window
object of the Document
object of t, and the detail
attribute initialized to 0, and must then dispatch the newly created FocusEvent
object
at the specified target element t.
When a key event is to be routed in a top-level browsing context, the user agent must run the following steps:
- Let target area be the currently focused area of the top-level browsing context.
- If target area is a focusable area, let target node be target area’s DOM anchor.
-
If target node is a
Document
that has abody
element, then let target node be thebody
element of thatDocument
.Otherwise, if target node is a
Document
that has a root element, then let target node be the root element of thatDocument
. -
If target node is not inert, fire the event at target node.
It is possible for the currently focused area of a top-level browsing context to be inert. It is likely to be the result of a logic error in the application, though.
- If the event was not canceled, then let target area handle the key event. This might include running synthetic click activation steps for target node.
The has focus steps, given a Document
object target, are
as follows:
- Let candidate be the
Document
of the top-level browsing context. - If candidate is target, return true and abort these steps.
-
If candidate has a non-empty control group, and the
designated focused area of the control group is a browsing context
container, and the active document of that browsing context
container’s nested browsing context is target, then
return true and abort these steps.
Otherwise, if candidate has a non-empty control group, and the designated focused area of the control group is a browsing context container, then let candidate be the active document of that browsing context container’s nested browsing context, and redo this step.
Otherwise, return false and abort these steps.
5.4.5. Sequential focus navigation
Each control group has a sequential focus navigation order, which orders some or all of the focusable areas in the control group relative to each other. The order in the sequential focus navigation order does not have to be related to the order in the control group itself. If a focusable area is omitted from the sequential focus navigation order of its control group, then it is unreachable via sequential focus navigation.
There can also be a sequential focus navigation starting point. It is initially unset. The user agent may set it when the user indicates that it should be moved.
For example, the user agent could set it to the position of the user’s click if the user clicks on the document contents.
When the user requests that focus move from the currently focused area of a top-level browsing context to the next or previous focusable area (e.g., as the default action of pressing the tab key), or when the user requests that focus sequentially move to a top-level browsing context in the first place (e.g., from the browser’s location bar), the user agent must use the following algorithm:
- Let starting point be the currently focused area of a top-level browsing context, if the user requested to move focus sequentially from there, or else the top-level browsing context itself, if the user instead requested to move focus from outside the top-level browsing context.
- If there is a sequential focus navigation starting point defined and it is inside starting point, then let starting point be the sequential focus navigation starting point instead.
-
Let direction be forward if the user requested the next control, and backward if the user requested the previous control.
Typically, pressing tab requests the next control, and pressing shift+tab requests the previous control.
-
Loop: Let selection mechanism be sequential if the starting point is a browsing context or if starting point is in its control group’s sequential focus navigation order.
Otherwise, starting point is not in its control group’s sequential focus navigation order; let selection mechanism be DOM.
- Let candidate be the result of running the sequential navigation search algorithm with starting point, direction, and selection mechanism as the arguments.
- If candidate is not null, then run the focusing steps for candidate and abort these steps.
- Otherwise, unset the sequential focus navigation starting point.
-
If starting point is the top-level browsing context, or a focusable area in the top-level browsing context, the user agent should transfer focus to its own controls appropriately (if any), honouring direction, and then abort these steps.
For example, if direction is backward, then the last focusable control before the browser’s rendering area would be the control to focus.
If the user agent has no focusable controls — a kiosk-mode browser, for instance — then the user agent may instead restart these steps with the starting point being the top-level browsing context itself.
- Otherwise, starting point is a focusable area in a nested browsing context. Let starting point be that nested browsing context’s browsing context container, and return to the step labeled loop.
The sequential navigation search algorithm consists of the following steps. This algorithm takes three arguments: starting point, direction, and selection mechanism.
-
Pick the appropriate cell from the following table, and follow the instructions in that cell.
The appropriate cell is the one that is from the column whose header describes direction and from the first row whose header describes starting point and selection mechanism.
direction is forward direction is backward starting point is a browsing context Let candidate be the first suitable sequentially focusable area in starting point’s active document’s primary control group, if any; or else null Let candidate be the last suitable sequentially focusable area in starting point’s active document’s primary control group, if any; or else null selection mechanism is DOM Let candidate be the first suitable sequentially focusable area in the home control group following starting point, if any; or else null Let candidate be the last suitable sequentially focusable area in the home control group preceding starting point, if any; or else null selection mechanism is sequential Let candidate be the first suitable sequentially focusable area in the home sequential focus navigation order following starting point, if any; or else null Let candidate be the last suitable sequentially focusable area in the home sequential focus navigation order preceding starting point, if any; or else null A suitable sequentially focusable area is a focusable area whose DOM anchor is not inert and that is in its control group’s sequential focus navigation order.
The primary control group of a control group owner object X is the control group of X.
The home control group is the control group to which starting point belongs.
The home sequential focus navigation order is the sequential focus navigation order to which starting point belongs.
The home sequential focus navigation order is the home control group’s sequential focus navigation order, but is only used when the starting point is in that sequential focus navigation order (when it’s not, selection mechanism will be DOM).
-
If candidate is a browsing context container, then let new candidate be the result of running the sequential navigation search algorithm with candidate’s nested browsing context as the first argument, direction as the second, and sequential as the third.
If new candidate is null, then let starting point be candidate, and return to the top of this algorithm. Otherwise, let candidate be new candidate.
- Return candidate.
5.4.6. Focus management APIs
- document .
activeElement
-
Returns the deepest element in the document through which or to which key events are being routed. This is, roughly speaking, the focused element in the document.
For the purposes of this API, when a child browsing context is focused, its browsing context container is focused in the parent browsing context. For example, if the user moves the focus to a text field in an
iframe
, theiframe
is the element returned by theactiveElement
API in theiframe
’s node document. - document .
hasFocus
() -
Returns true if key events are being routed through or to the document; otherwise, returns false. Roughly speaking, this corresponds to the document, or a document nested inside this one, being focused.
- window .
focus
() -
Moves the focus to the window’s browsing context, if any.
- element .
focus
() -
Moves the focus to the element.
If the element is a browsing context container, moves the focus to the nested browsing context instead.
- element .
blur
() -
Moves the focus to the viewport. Use of this method is discouraged; if you want to focus the viewport, call the
focus()
method on theDocument
’s root element.Do not use this method to hide the focus ring if you find the focus ring unsightly. Instead, use a CSS rule to override the outline property, and provide a different way to show what element is focused. Be aware that if an alternative focusing style isn’t made available, the page will be significantly less usable for people who primarily navigate pages using a keyboard, or those with reduced vision who use focus outlines to help them navigate the page.
For example, to hide the outline from links and instead use a yellow background to indicate focus, you could use::link:focus, :visited:focus { outline: none; background: yellow; color: black; }
Do not use this method to hide the focus ring. Do not use any other method that hides the focus ring from keyboard users, in particular do not use a CSS rule to override the outline property. Removal of the focus ring leads to serious accessibility issues for users who navigate and interact with interactive content using the keyboard.
The activeElement
attribute on Document
objects must return the value returned by the following steps:
- Let candidate be the
Document
on which the method was invoked. - If candidate has a non-empty control group, let candidate be the designated focused area of the control group.
- If candidate is a focusable area, let candidate be candidate’s DOM anchor.
-
If candidate is a
Document
that has abody
element, then let candidate be thebody
element of thatDocument
.Otherwise, if candidate is a
Document
that has a root element, then let candidate be the root element of thatDocument
.Otherwise, if candidate is a
Document
, then let candidate be null. - Return candidate.
The hasFocus()
method on the Document
object, when invoked, must return the result of running the has focus
steps with the Document
object as the argument.
The focus()
method on the Window
object, when invoked, must run the focusing steps with the Window
object’s browsing context. Additionally, if this browsing context is a top-level browsing context, user agents are encouraged to trigger some sort of
notification to indicate to the user that the page is attempting to gain focus.
The blur()
method on the Window
object, when invoked, provides a hint to the user agent that the script believes the user probably
is not currently interested in the contents of the browsing context of the Window
object on which the method was invoked, but that the contents might become
interesting again in the future.
User agents are encouraged to ignore calls to this blur()
method entirely.
Historically, the focus()
and blur()
methods actually affected the system-level focus of the
system widget (e.g., tab or window) that contained the browsing context, but hostile
sites widely abuse this behavior to the user’s detriment.
The focus()
method on elements, when invoked, must
run the following algorithm:
- If the element is marked as locked for focus, then abort these steps.
- Mark the element as locked for focus.
- Run the focusing steps for the element.
- Unmark the element as locked for focus.
The blur()
method, when invoked, should run the unfocusing steps for the element on which the method was called. User agents may
selectively or uniformly ignore calls to this method for usability reasons.
For example, if the blur()
method is unwisely
being used to remove the focus ring for aesthetics reasons, the page would become unusable by
keyboard users. Ignoring calls to this method would thus allow keyboard users to interact with the
page.
5.5. Assigning keyboard shortcuts
5.5.1. Introduction
This section is non-normative.
Each element that can be activated or focused can be assigned a shortcut key combination to
activate it, using the accesskey
attribute.
The exact shortcut is determined by the user agent, potentially using information about the user’s
preferences, what keyboard shortcuts already exist on the platform, and what other shortcuts have
been specified on the page, as well as the value of the accesskey
attribute.
A valid value for accesskey
consists of a single character, such as a letter or digit.
User agents can provide users with a list of the keyboard shortcuts, but authors are encouraged to do so also.
<input type=button value=Collect onclick="collect()" accesskey="C" id=c>
5.5.2. The accesskey
attribute
All html elements may have the accesskey
content attribute set. The accesskey
attribute’s value is used
by the user agent as a guide for creating a keyboard shortcut that activates or focuses the
element.
If specified, the value must be a single printable character: a string exactly one Unicode code point in length.
Authors should not use " ", nor characters that normally require a modifier key to
generate, as a value of accesskey
.
<nav> <p> <a title="Consortium Activities" accesskey="A" href="/Consortium/activities">Activities</a> | <a title="Technical Reports and Recommendations" accesskey="T" href="/TR/">Technical Reports</a> | <a title="Alphabetical Site Index" accesskey="S" href="/Consortium/siteindex">Site Index</a> | <a title="About This Site" accesskey="B" href="/Consortium/">About Consortium</a> | <a title="Contact Consortium" accesskey="C" href="/Consortium/contact">Contact</a> </p> </nav>
5.5.3. Processing model
An element’s assigned access key is a key combination derived from the element’s accesskey
content attribute, or assigned by the user agent, optionally
based on a user preference. Initially, an element must not have an assigned access key.
Whenever an element’s accesskey
attribute is set, changed,
or removed, the user agent must update the element’s assigned access key by running
the following steps:
- If the element has no
accesskey
attribute, then skip to the fallback step below. - The user agent may assign a key combination based on stored user preferences as the element’s assigned access key and then abort these steps.
- Let value be the value of the
accesskey
attribute. - The user agent may strip content from value to reduce the length of value to a single unicode code point.
- If value is not a string exactly one Unicode code point in length, then abort these steps.
- The user agent may assign a combination of a mix of zero or more modifier keys and value as the element’s assigned access key and abort these steps.
- Fallback: Optionally, the user agent may assign a key combination of its choosing as the element’s assigned access key and then abort these steps.
- If this step is reached, the element has no assigned access key.
Once a user agent has selected and assigned an access key for an element, the user agent should
not change the element’s assigned access key unless the accesskey
content
attribute is changed or the element is moved to another Document
.
When the user presses the key combination corresponding to the assigned access key for an element, if the element defines a command, the
command’s facet is false (visible),
the command’s Disabled State facet is also false
(enabled), the element is in a Document
that has an associated browsing context, and neither the element nor any of its ancestors has a hidden
attribute specified, then the user agent must trigger the Action of the command.
User agents might expose elements that have
an accesskey
attribute in other ways as well, e.g., in a menu
displayed in response to a specific key combination.
The accessKey
IDL attribute must reflect the accesskey
content attribute.
5.6. Editing
5.6.1. Making document regions editable: The contenteditable
content attribute
[NoInterfaceObject] interface ElementContentEditable { attribute DOMString contentEditable; readonly attribute boolean isContentEditable; };
The contenteditable
content attribute is an enumerated attribute whose keywords are the empty string, true
,
and false
. The empty string and the true
keyword map
to the true state. The false
keyword maps to the false state.
In addition, there is a third state, the inherit state, which is the missing value default (and the invalid value default).
The true state indicates that the element is editable. The inherit state indicates that the element is editable if its parent is. The false state indicates that the element is not editable.
- element .
contentEditable
[ = value ] -
Returns "
true
", "false
", or "inherit
", based on the state of thecontenteditable
attribute.Can be set, to change that state.
Throws a "
SyntaxError
"DOMException
if the new value isn’t one of those strings. - element .
isContentEditable
-
Returns true if the element is editable; otherwise, returns false.
The contentEditable
IDL attribute, on
getting, must return the string "true
" if the content attribute is set to
the true state, "false
" if the content attribute is set to the false state,
and "inherit
" otherwise. On setting, if the new value is an ASCII
case-insensitive match for the string "inherit
" then the content
attribute must be removed, if the new value is an ASCII case-insensitive match for
the string "true
" then the content attribute must be set to the string
"true
", if the new value is an ASCII case-insensitive match for
the string "false
" then the content attribute must be set to the string
"false
", and otherwise the attribute setter must throw a
"SyntaxError
" DOMException
.
The isContentEditable
IDL attribute, on
getting, must return true if the element is either an editing host or editable, and false otherwise.
5.6.2. Making entire documents editable: The designMode
IDL attribute
- document .
designMode
[ = value ] -
Returns "
on
" if the document is editable, and "off
" if it isn’t.Can be set, to change the document’s current state. This focuses the document and resets the selection in that document.
The designMode
IDL attribute on the Document
object takes two values, "on
" and "off
". On setting, the new value must be compared in an ASCII
case-insensitive manner to these two values; if it matches the "on
"
value, then designMode
must be enabled, and if it
matches the "off
" value, then designMode
must be disabled. Other values must be
ignored.
On getting, if designMode
is enabled, the IDL
attribute must return the value "on
"; otherwise it is disabled, and the
attribute must return the value "off
".
The last state set must persist until the document is destroyed or the state is changed.
Initially, documents must have their designMode
disabled.
When the designMode
changes from being disabled to
being enabled, the user agent must immediately reset the document’s active range’s
start and end boundary points to be at the start of the Document
and then run the focusing steps for the root element of the Document
, if any.
5.6.3. Best practices for in-page editors
Authors are encouraged to set the white-space property on editing hosts and on markup that was originally created through these editing mechanisms to the value pre-wrap. Default HTML whitespace handling is not well suited to WYSIWYG editing, and line wrapping will not work correctly in some corner cases if white-space is left at its default value.
In the former case, "yellow⍽" might wrap to the next line ("⍽" being used here to represent a non-breaking space) even though "yellow" alone might fit at the end of the line; in the latter case, "⍽ball", if wrapped to the start of the line, would have visible indentation from the non-breaking space.
When white-space is set to pre-wrap, however, the editing rules will instead simply put two regular spaces between the words, and should the two words be split at the end of a line, the spaces would be neatly removed from the rendering.
5.6.4. Editing APIs
The definition of the terms active range, editing host, and editable, the user interface requirements of elements that are editing hosts or editable, the execCommand()
, queryCommandEnabled()
, queryCommandIndeterm()
, queryCommandState()
, queryCommandSupported()
, and queryCommandValue()
methods, text selections, and the delete the selection algorithm are being specified in the various developing
HTML Editing specification drafts [EDITING]. The interaction of editing and undo/redo
features are being specified in the UndoManager and DOM Transaction specification. [UNDO]
5.6.5. Spelling and grammar checking
User agents can support the checking of spelling and grammar of editable text, either in form
controls (such as the value of textarea
elements), or in elements in an editing
host (e.g., using contenteditable
).
For each element, user agents must establish a default behavior, either through defaults or through preferences expressed by the user. There are three possible default behaviors for each element:
- true-by-default
- The element will be checked for spelling and grammar if its contents are editable and
spellchecking is not explicitly disabled through the
spellcheck
attribute. - false-by-default
- The element will never be checked for spelling and grammar unless spellchecking is
explicitly enabled through the
spellcheck
attribute. - inherit-by-default
- The element’s default behavior is the same as its parent element’s. Elements that have no parent element cannot have this as their default behavior.
The spellcheck
attribute is an enumerated
attribute whose keywords are the empty string, true
and false
. The empty string and the true
keyword map to the true state. The false
keyword maps to the false state. In
addition, there is a third state, the default state, which is the missing value default (and the invalid value default).
The true state indicates that the element is to have its spelling and
grammar checked. The default state indicates that the element is to act according to a
default behavior, possibly based on the parent element’s own spellcheck
state, as defined below. The false state
indicates that the element is not to be checked.
- element .
spellcheck
[ = value ] -
Returns true if the element is to have its spelling and grammar checked; otherwise, returns false.
Can be set, to override the default and set the
spellcheck
content attribute. - element .
forceSpellCheck
() -
Forces the user agent to report spelling and grammar errors on the element (if checking is enabled), even if the user has never focused the element. (If the method is not invoked, user agents can hide errors in text that wasn’t just entered by the user.)
The spellcheck
IDL attribute, on getting, must
return true if the element’s spellcheck
content attribute is
in the true state, or if the element’s spellcheck
content attribute is in the default state and the element’s default behavior is true-by-default, or if the element’s spellcheck
content attribute is in the default state and the
element’s default behavior is inherit-by-default and the element’s parent
element’s spellcheck
IDL attribute would return true;
otherwise, if none of those conditions applies, then the attribute must instead return false.
The spellcheck
IDL attribute is not affected
by user preferences that override the spellcheck
content
attribute, and therefore might not reflect the actual spellchecking state.
On setting, if the new value is true, then the element’s spellcheck
content attribute must be set to the literal string
"true
", otherwise it must be set to the literal string "false
".
User agents must only consider the following pieces of text as checkable for the purposes of this feature:
- The value of
input
elements whosetype
attributes are in the Text, Search, URL, or E-mail states and that are mutable (i.e., that do not have thereadonly
attribute specified and that are not disabled). - The value of
textarea
elements that do not have areadonly
attribute and that are not disabled. - Text in
Text
nodes that are children of editing hosts or editable elements. - Text in attributes of editable elements.
For text that is part of a Text
node, the element with which the text is
associated is the element that is the immediate parent of the first character of the word,
sentence, or other piece of text. For text in attributes, it is the attribute’s element. For the
values of input
and textarea
elements, it is the element itself.
To determine if a word, sentence, or other piece of text in an applicable element (as defined above) is to have spelling- and grammar-checking enabled, the user agent must use the following algorithm:
- If the user has disabled the checking for this text, then the checking is disabled.
- Otherwise, if the user has forced the checking for this text to always be enabled, then the checking is enabled.
- Otherwise, if the element with which the text is associated has a
spellcheck
content attribute, then: if that attribute is in the true state, then checking is enabled; otherwise, if that attribute is in the false state, then checking is disabled. - Otherwise, if there is an ancestor element with a
spellcheck
content attribute that is not in the default state, then: if the nearest such ancestor’sspellcheck
content attribute is in the true state, then checking is enabled; otherwise, checking is disabled. - Otherwise, if the element’s default behavior is true-by-default, then checking is enabled.
- Otherwise, if the element’s default behavior is false-by-default, then checking is disabled.
- Otherwise, if the element’s parent element has its checking enabled, then checking is enabled.
- Otherwise, checking is disabled.
If the checking is enabled for a word/sentence/text, the user agent should indicate spelling
and grammar errors in that text. User agents should take into account the other semantics given in
the document when suggesting spelling and grammar corrections. User agents may use the language of
the element to determine what spelling and grammar rules to use, or may use the user’s preferred
language settings. user agents should use input
element attributes such as pattern
to ensure that the resulting value is valid, where
possible.
If checking is disabled, the user agent should not indicate spelling or grammar errors for that text.
Even when checking is enabled, user agents may opt to not report spelling or grammar errors in
text that the user agent deems the user has no interest in having checked (e.g., text that was
already present when the page was loaded, or that the user did not type, or text in controls that
the user has not focused, or in parts of e-mail addresses that the user agent is not confident
were misspelt). The forceSpellCheck()
method,
when invoked on an element, must override this behavior, forcing the user agent to consider all
spelling and grammar errors in text in that element for which checking is enabled to be of
interest to the user.
<div contenteditable="true"> <span spellcheck="false">Hell</span><em>o!</em> </div>
The element with ID "b" in the following example would have checking enabled (the leading
space character in the attribute’s value on the input
element causes the attribute
to be ignored, so the ancestor’s value is used instead, regardless of the default).
<p spellcheck="true"><label>Name: <input spellcheck=" false"></label> </p>
This specification does not define the user interface for spelling and grammar checkers. A user agent could offer on-demand checking, could perform continuous checking while the checking is enabled, or could use other interfaces.
5.7. Drag and drop
This section defines an event-based drag-and-drop mechanism.
This specification does not define exactly what a drag-and-drop operation actually is.
On a visual medium with a pointing device, a drag operation could be the default action of a mousedown
event that is followed by a series of mousemove
events, and the drop could be triggered by the mouse
being released.
When using an input modality other than a pointing device, users would probably have to explicitly indicate their intention to perform a drag-and-drop operation, stating what they wish to drag and where they wish to drop it, respectively.
However it is implemented, drag-and-drop operations must have a starting point (e.g., where the mouse was clicked, or the start of the selection or element that was selected for the drag), may have any number of intermediate steps (elements that the mouse moves over during a drag, or elements that the user picks as possible drop points as he cycles through possibilities), and must either have an end point (the element above which the mouse button was released, or the element that was finally selected), or be canceled. The end point must be the last element selected as a possible drop point before the drop occurs (so if the operation is not canceled, there must be at least one element in the middle step).
5.7.1. Introduction
This section is non-normative.
To make an element draggable is simple: give the element a draggable
attribute, and set an event listener for dragstart
that stores the data being dragged.
The event handler typically needs to check that it’s not a text selection that is being
dragged, and then needs to store data into the DataTransfer
object and set the
allowed effects (copy, move, link, or some combination).
For example:
<p>What fruits do you like?</p> <ol ondragstart="dragStartHandler(event)"> <li draggable="true">Apples</li> <li draggable="true">Oranges</li> <li draggable="true">Pears</li> </ol> <script> var internalDNDType = 'text/x-example'; // set this to something specific to your site function dragStartHandler(event) { if (event.target instanceof HTMLLIElement) { // use the element’s>
To accept a drop, the drop target has to have a dropzone
attribute and listen to the drop
event.
The value of the dropzone
attribute specifies what kind of
data to accept (e.g., "string:text/plain
" to accept any text strings, or
"file:image/png
" to accept a PNG image file) and what kind of feedback to
give (e.g., "move
" to indicate that the data will be moved).
Instead of using the dropzone
attribute, a drop
target can handle the dragenter
event (to report whether or
not the drop target is to accept the drop) and the dragover
event (to specify what feedback is to be shown to the user).
The drop
event allows the actual drop to be performed. This
event needs to be canceled, so that the dropEffect
attribute’s value can be used by the source
(otherwise it’s reset).
For example:
<p>Drop your favorite fruits below:</p> <ol dropzone="move string:text/x-example" ondrop="dropHandler(event)"> <!-- don’t forget to change the "text/x-example" type to something specific to your site --> </ol> <script> var internalDNDType = 'text/x-example'; // set this to something specific to your site function dropHandler(event) { var li = document.createElement('li'); var data = event.dataTransfer.getData(internalDNDType); if (data == 'fruit-apple') { li.textContent = 'Apples'; } else if (data == 'fruit-orange') { li.textContent = 'Oranges'; } else if (data == 'fruit-pear') { li.textContent = 'Pears'; } else { li.textContent = 'Unknown Fruit'; } event.target.appendChild(li); } </script>
To remove the original element (the one that was dragged) from the display, the dragend
event can be used.
For our example here, that means updating the original markup to handle that event:
<p>What fruits do you like?</p> <ol ondragstart="dragStartHandler(event)" ondragend="dragEndHandler(event)"> <!-- ...as before... --> </ol> <script> function dragStartHandler(event) { // ...as before... } function dragEndHandler(event) { if (event.dataTransfer.dropEffect == 'move') { // remove the dragged element event.target.parentNode.removeChild(event.target); } } </script>
5.7.2. The drag data store
The data that underlies a drag-and-drop operation, known as the drag data store, consists of the following information:
-
A drag data store item list, which is a list of items representing the dragged
data, each consisting of the following information:
- The drag data item kind
-
The kind of data:
- Plain Unicode string
- Text.
- File
- Binary data with a file name.
- The drag data item type string
-
A Unicode string giving the type or format of the data, generally given by a MIME type. Some values that are not MIME types are special-cased for legacy reasons. The API does not enforce the use of MIME types; other values can be used as well. In all cases, however, the values are all converted to ASCII lowercase by the API.
Strings that contain space characters cannot be used with the
dropzone
attribute, so authors are encouraged to use only MIME types or custom strings (without spaces).There is a limit of one Plain Unicode string item per item type string.
- The actual data
- A Unicode or binary string, in some cases with a file name (itself a Unicode string), as per the drag data item kind.
The drag data store item list is ordered in the order that the items were added to the list; most recently added last.
-
The following information, used to generate the UI feedback during the drag:
- User-agent-defined default feedback information, known as the drag data store default feedback.
- Optionally, a bitmap image and the coordinate of a point within that image, known as the drag data store bitmap and drag data store hot spot coordinate.
-
A drag data store mode, which is one of the following:
- Read/write mode
-
For the
dragstart
event. New data can be added to the drag data store. - Read-only mode
-
For the
drop
event. The list of items representing dragged data can be read, including the data. No new data can be added. - Protected mode
-
For all other events. The formats and kinds in the drag data store list of items representing dragged data can be enumerated, but the data itself is unavailable and no new data can be added.
-
A drag data store allowed effects state, which is a string.
When a drag data store is created, it
must be initialized such that its drag data store item list is empty, it has no drag data store default feedback, it has no drag data store bitmap and drag data store hot spot coordinate, its drag data store mode is protected mode, and its drag data store allowed effects
state is the string "uninitialized
".
5.7.3. The DataTransfer
interface
DataTransfer
objects are used to expose the drag data store that
underlies a drag-and-drop operation.
interface DataTransfer { attribute DOMString dropEffect; attribute DOMString effectAllowed; [SameObject] readonly attribute DataTransferItemList items; void setDragImage(Element image, long x, long y); /* old interface */ [SameObject] readonly attribute DOMString[] types; DOMString getData(DOMString format); void setData(DOMString format, DOMString data); void clearData(optional DOMString format); [SameObject] readonly attribute FileList files; };
- dataTransfer .
dropEffect
[ = value ] -
Returns the kind of operation that is currently selected. If the kind of operation isn’t one of those that is allowed by the
effectAllowed
attribute, then the operation will fail.Can be set, to change the selected operation.
The possible values are "
none
", "copy
", "link
", and "move
". - dataTransfer .
effectAllowed
[ = value ] -
Returns the kinds of operations that are to be allowed.
Can be set (during the
dragstart
event), to change the allowed operations.The possible values are "
none
", "copy
", "copyLink
", "copyMove
", "link
", "linkMove
", "move
", "all
", and "uninitialized
", - dataTransfer .
items
-
Returns a
DataTransferItemList
object, with the drag data. - dataTransfer .
setDragImage
(element, x, y) -
Uses the given element to update the drag feedback, replacing any previously specified feedback.
- dataTransfer .
types
-
Returns an array listing the formats that were set in the
dragstart
event. In addition, if any files are being dragged, then one of the types will be the string "Files
". - data = dataTransfer .
getData
(format) -
Returns the specified data. If there is no such data, returns the empty string.
- dataTransfer .
setData
(format, data) -
Adds the specified data.
- dataTransfer .
clearData
( [ format ] ) -
Removes the data of the specified formats. Removes all data if the argument is omitted.
- dataTransfer .
files
-
Returns a
FileList
of the files being dragged, if any.
DataTransfer
objects are used during the drag-and-drop events, and are only valid while those events are being fired.
A DataTransfer
object is associated with a drag data store while it
is valid.
The dropEffect
attribute controls
the drag-and-drop feedback that the user is given during a drag-and-drop operation. When the DataTransfer
object is created, the dropEffect
attribute is set to a string value. On
getting, it must return its current value. On setting, if the new value is one of "none
", "copy
", "link
", or "move
", then the attribute’s current value must be
set to the new value. Other values must be ignored.
The effectAllowed
attribute is
used in the drag-and-drop processing model to initialize the dropEffect
attribute during the dragenter
and dragover
events. When the DataTransfer
object is
created, the effectAllowed
attribute is set
to a string value. On getting, it must return its current value. On setting, if drag data
store’s mode is the read/write mode and the new value is one of "none
", "copy
", "copyLink
", "copyMove
", "link
", "linkMove
", "move
", "all
", or "uninitialized
", then the attribute’s
current value must be set to the new value. Otherwise it must be left unchanged.
The items
attribute must return a DataTransferItemList
object associated with the DataTransfer
object.
The setDragImage(element, x, y)
method must run the following steps:
- If the
DataTransfer
object is no longer associated with a drag data store, abort these steps. Nothing happens. - If the drag data store’s mode is not the read/write mode, abort these steps. Nothing happens.
- If the element argument is an
img
element, then set the drag data store bitmap to the element’s image (at its intrinsic size); otherwise, set the drag data store bitmap to an image generated from the given element (the exact mechanism for doing so is not currently specified). - Set the drag data store hot spot coordinate to the given x, y coordinate.
The types
attribute must return a live read only array giving the strings
that the following steps would produce.
- Start with an empty list L.
- If the
DataTransfer
object is no longer associated with a drag data store, the array is empty. Abort these steps; return the empty list L. - For each item in the drag data store item list whose
kind
is Plain Unicode string, add an entry to the list L consisting of the item’s type string. - If there are any items in the drag data store item list whose
kind
is File, then add an entry to the list L consisting of the string "Files
". (This value can be distinguished from the other values because it is not lowercase.) - The strings produced by these steps are those in the list L.
The getData(format)
method
must run the following steps:
- If the
DataTransfer
object is no longer associated with a drag data store, return the empty string and abort these steps. - If the drag data store’s mode is the protected mode, return the empty string and abort these steps.
- Let format be the first argument, converted to ASCII lowercase.
- Let convert-to-URL be false.
- If format equals "
text
", change it to "text/plain
". - If format equals "
url
", change it to "text/uri-list
" and set convert-to-URL to true. - If there is no item in the drag data store item list whose
kind
is Plain Unicode string and whose type string is equal to format, return the empty string and abort these steps. - Let result be the data of the item in the drag data store item
list whose
kind
is Plain Unicode string and whose type string is equal to format. - If convert-to-URL is true, then parse result as appropriate for
text/uri-list
data, and then set result to the first URL from the list, if any, or the empty string otherwise. [RFC2483] - Return result.
The setData(format, data)
method must run the following steps:
- If the
DataTransfer
object is no longer associated with a drag data store, abort these steps. Nothing happens. - If the drag data store’s mode is not the read/write mode, abort these steps. Nothing happens.
- Let format be the first argument, converted to ASCII lowercase.
-
If format equals "
text
", change it to "text/plain
".If format equals "
url
", change it to "text/uri-list
". - Remove the item in the drag data store item list whose
kind
is Plain Unicode string and whose type string is equal to format, if there is one. - Add an item to the drag data store item list whose
kind
is Plain Unicode string, whose type string is equal to format, and whose data is the string given by the method’s second argument.
The clearData()
method must run the
following steps:
- If the
DataTransfer
object is no longer associated with a drag data store, abort these steps. Nothing happens. - If the drag data store’s mode is not the read/write mode, abort these steps. Nothing happens.
- If the method was called with no arguments, remove each item in the drag data store
item list whose
kind
is Plain Unicode string, and abort these steps. - Let format be the first argument, converted to ASCII lowercase.
-
If format equals "
text
", change it to "text/plain
".If format equals "
url
", change it to "text/uri-list
". - Remove the item in the drag data store item list whose
kind
is Plain Unicode string and whose type string is equal to format, if there is one.
The clearData()
method does not
affect whether any files were included in the drag, so the types
attribute’s list might still not be empty after
calling clearData()
(it would still contain the
"Files
" string if any files were included in the drag).
The files
attribute must return a live FileList
sequence consisting of File
objects
representing the files found by the following steps.
Furthermore, for a given FileList
object and a given underlying file, the same File
object must be used each time.
- Start with an empty list L.
- If the
DataTransfer
object is no longer associated with a drag data store, theFileList
is empty. Abort these steps; return the empty list L. - If the drag data store’s mode is the protected mode, abort these steps; return the empty list L.
- For each item in the drag data store item list whose
kind
is File , add the item’s data (the file, in particular its name and contents, as well as its type) to the list L. - The files found by these steps are those in the list L.
This version of the API does not expose the types of the files during the drag.
5.7.3.1. The DataTransferItemList
interface
Each DataTransfer
object is associated with a DataTransferItemList
object.
interface DataTransferItemList { readonly attribute unsigned long length; getter DataTransferItem (unsigned long index); DataTransferItem? add(DOMString data, DOMString type); DataTransferItem? add(File data); void remove(unsigned long index); void clear(); };
- items .
length
- Returns the number of items in the drag data store.
- items[index]
-
Returns the
DataTransferItem
object representing the indexth entry in the drag data store. - items .
remove
(index) -
Removes the indexth entry in the drag data store.
- items .
clear()
-
Removes all the entries in the drag data store.
- items .
add
(data)- items .
add
(data, type) - items .
-
Adds a new entry for the given data to the drag data store. If the data is plain text then a type string has to be provided also.
While the DataTransferItemList
object’s DataTransfer
object is
associated with a drag data store, the DataTransferItemList
object’s mode is the same as the drag data store mode. When the DataTransferItemList
object’s DataTransfer
object is not associated with a drag data store, the DataTransferItemList
object’s mode is the disabled mode. The drag data store referenced in this
section (which is used only when the DataTransferItemList
object is not in the disabled mode) is the drag data store with which the DataTransferItemList
object’s DataTransfer
object is associated.
The length
attribute must
return zero if the object is in the disabled mode; otherwise it must return the number of
items in the drag data store item list.
When a DataTransferItemList
object is not in the disabled mode, its supported property indices are the numbers in the range 0 .. n-1, where n is the number of items in the drag data store item list.
To determine the value of an indexed property i of a DataTransferItemList
object, the user agent must return a DataTransferItem
object representing the ith item in the drag data store. The same object must be returned each time a particular item is
obtained from this DataTransferItemList
object. The DataTransferItem
object must be associated with the same DataTransfer
object as the DataTransferItemList
object when it is first created.
The add()
method must run the
following steps:
- If the
DataTransferItemList
object is not in the read/write mode, return null and abort these steps. -
Jump to the appropriate set of steps from the following list:
- If the first argument to the method is a string
-
If there is already an item in the drag data store item list whose
kind
is Plain Unicode string and whose type string is equal to the value of the method’s second argument, converted to ASCII lowercase, then throw aNotSupportedError
exception and abort these steps.Otherwise, add an item to the drag data store item list whose
kind
is Plain Unicode string, whose type string is equal to the value of the method’s second argument, converted to ASCII lowercase, and whose data is the string given by the method’s first argument. - If the first argument to the method is a
File
-
Add an item to the drag data store item list whose
kind
is File, whose type string is thetype
of theFile
, converted to ASCII lowercase, and whose data is the same as theFile
’s data.
- Determine the value of the indexed property corresponding to the newly added item, and return that value (a newly created
DataTransferItem
object).
The remove()
method, when
invoked with the argument i, must run these steps:
- If the
DataTransferItemList
object is not in the read/write mode, throw anInvalidStateError
exception and abort these steps. - Remove the ith item from the drag data store.
The clear()
method, if the DataTransferItemList
object is in the read/write mode,
must remove all the items from the drag data store. Otherwise, it must do
nothing.
5.7.3.2. The DataTransferItem
interface
Each DataTransferItem
object is associated with a DataTransfer
object.
interface DataTransferItem { readonly attribute DOMString kind; readonly attribute DOMString type; void getAsString(FunctionStringCallback? _callback); File? getAsFile(); }; callback FunctionStringCallback = void (DOMString data);
- item .
kind
-
Returns the drag data item kind, one of: "string", "file".
- item .
type
-
Returns the drag data item type string.
- item .
getAsString
(callback) -
Invokes the callback with the string data as the argument, if the drag data item kind is Plain Unicode string.
- file = item .
getAsFile()
-
Returns a
File
object, if the drag data item kind is File.
While the DataTransferItem
object’s DataTransfer
object is associated
with a drag data store and that drag data store’s drag data store
item list still contains the item that the DataTransferItem
object represents,
the DataTransferItem
object’s mode is the same as the drag data store
mode. When the DataTransferItem
object’s DataTransfer
object is not associated with a drag data store, or if the item that the DataTransferItem
object represents has been removed from the relevant drag data
store item list, the DataTransferItem
object’s mode is the disabled
mode. The drag data store referenced in this section (which is used only when the DataTransferItem
object is not in the disabled mode) is the drag data
store with which the DataTransferItem
object’s DataTransfer
object is associated.
The kind
attribute must return the
empty string if the DataTransferItem
object is in the disabled mode; otherwise
it must return the string given in the cell from the second column of the following table from the
row whose cell in the first column contains the drag data item kind of the item
represented by the DataTransferItem
object:
Kind | String |
---|---|
Plain Unicode string | "string "
|
File | "file "
|
The type
attribute must return the
empty string if the DataTransferItem
object is in the disabled mode; otherwise
it must return the drag data item type string of the item represented by the DataTransferItem
object.
The getAsString(callback)
method must run the following steps:
- If the callback is null, abort these steps.
- If the
DataTransferItem
object is not in the read/write mode or the read-only mode, abort these steps. The callback is never invoked. - If the drag data item kind is not Plain Unicode string, abort these steps. The callback is never invoked.
- Otherwise, queue a task to invoke callback, passing the
actual data of the item represented by the
DataTransferItem
object as the argument.
The getAsFile()
method must run the following steps:
- If the
DataTransferItem
object is not in the read/write mode or the read-only mode, return null and abort these steps. - If the drag data item kind is not File, then return null and abort these steps.
- Return a new
File
object representing the actual data of the item represented by theDataTransferItem
object.
5.7.4. The DragEvent
interface
The drag-and-drop processing model involves several events. They all use the DragEvent
interface.
[Constructor(DOMString type, optional DragEventInit eventInitDict)] interface DragEvent : MouseEvent { readonly attribute DataTransfer? dataTransfer; }; dictionary DragEventInit : MouseEventInit { DataTransfer? dataTransfer = null; };
- event .
dataTransfer
-
Returns the
DataTransfer
object for the event.
Although, for consistency with other event interfaces, the DragEvent
interface has a constructor, it is not particularly useful. In particular, there’s no way to
create a useful DataTransfer
object from script, as DataTransfer
objects
have a processing and security model that is coordinated by the browser during drag-and-drops.
The dataTransfer
attribute of the DragEvent
interface must return the value it was initialized to. It represents the
context information for the event.
When a user agent is required to fire a DND event named e at an element, using a particular drag data store, and optionally with a specific related target, the user agent must run the following steps:
- If no specific related target was provided, set related target to null.
- Let window be the
Window
object of theDocument
object of the specified target element. -
If e is
dragstart
, set the drag data store mode to the read/write mode.If e is
drop
, set the drag data store mode to the read-only mode. - Let dataTransfer be a newly created
DataTransfer
object associated with the given drag data store. - Set the
effectAllowed
attribute to the drag data store’s drag data store allowed effects state. -
Set the
dropEffect
attribute to "none
" if e isdragstart
,drag
,dragexit
, ordragleave
; to the value corresponding to the current drag operation if e isdrop
ordragend
; and to a value based on theeffectAllowed
attribute’s value and the drag-and-drop source, as given by the following table, otherwise (i.e., if e isdragenter
ordragover
):effectAllowed
dropEffect
" none
"" none
"" copy
"" copy
"" copyLink
"" copy
", or, if appropriate, "link
"" copyMove
"" copy
", or, if appropriate, "move
"" all
"" copy
", or, if appropriate, either "link
" or "move
"" link
"" link
"" linkMove
"" link
", or, if appropriate, "move
"" move
"" move
"" uninitialized
" when what is being dragged is a selection from a text field" move
", or, if appropriate, either "copy
" or "link
"" uninitialized
" when what is being dragged is a selection" copy
", or, if appropriate, either "link
" or "move
"" uninitialized
" when what is being dragged is ana
element with anhref
attribute" link
", or, if appropriate, either "copy
" or "move
"Any other case " copy
", or, if appropriate, either "link
" or "move
"Where the table above provides possibly appropriate alternatives, user agents may instead use the listed alternative values if platform conventions dictate that the user has requested those alternate effects.
For example, Windows platform conventions are such that dragging while holding the "alt" key indicates a preference for linking the data, rather than moving or copying it. Therefore, on a Windows system, if "
link
" is an option according to the table above while the "alt" key is depressed, the user agent could select that instead of "copy
" or "move
". -
Create a trusted
DragEvent
object and initialize it to have the given name e, to bubble, to be cancelable unless e isdragexit
,dragleave
, ordragend
, and to have theview
attribute initialized to window, thedetail
attribute initialized to zero, the mouse and key attributes initialized according to the state of the input devices as they would be for user interaction events, therelatedTarget
attribute initialized to related target, and thedataTransfer
attribute initialized to dataTransfer, theDataTransfer
object created above.If there is no relevant pointing device, the object must have its
screenX
,screenY
,clientX
,clientY
, andbutton
attributes set to 0. - Dispatch the newly created
DragEvent
object at the specified target element. - Set the drag data store allowed effects state to the current value of dataTransfer’s
effectAllowed
attribute. (It can only have changed value if e isdragstart
.) - Set the drag data store mode back to the protected mode if it was changed in the first step.
- Break the association between dataTransfer and the drag data store.
5.7.5. Drag-and-drop processing model
When the user attempts to begin a drag operation, the user agent must run the following steps. User agents must act as if these steps were run even if the drag actually started in another document or application and the user agent was not aware that the drag was occurring until it intersected with a document under the user agent’s purview.
-
Determine what is being dragged, as follows:
If the drag operation was invoked on a selection, then it is the selection that is being dragged.
Otherwise, if the drag operation was invoked on a
Document
, it is the first element, going up the ancestor chain, starting at the node that the user tried to drag, that has the IDL attributedraggable
set to true. If there is no such element, then nothing is being dragged; abort these steps, the drag-and-drop operation is never started.Otherwise, the drag operation was invoked outside the user agent’s purview. What is being dragged is defined by the document or application where the drag was started.
img
elements anda
elements with anhref
attribute have theirdraggable
attribute set to true by default. - Create a drag data store. All the DND events fired subsequently by the steps in this section must use this drag data store.
-
Establish which DOM node is the source node, as follows:
If it is a selection that is being dragged, then the source node is the
Text
node that the user started the drag on (typically theText
node that the user originally clicked). If the user did not specify a particular node, for example if the user just told the user agent to begin a drag of "the selection", then the source node is the firstText
node containing a part of the selection.Otherwise, if it is an element that is being dragged, then the source node is the element that is being dragged.
Otherwise, the source node is part of another document or application. When this specification requires that an event be dispatched at the source node in this case, the user agent must instead follow the platform-specific conventions relevant to that situation.
Multiple events are fired on the source node during the course of the drag-and-drop operation.
-
Determine the list of dragged nodes, as follows:
If it is a selection that is being dragged, then the list of dragged nodes contains, in tree order, every node that is partially or completely included in the selection (including all their ancestors).
Otherwise, the list of dragged nodes contains only the source node, if any.
-
If it is a selection that is being dragged, then add an item to the drag data store item list, with its properties set as follows:
- The drag data item type string
- "
text/plain
" - The drag data item kind
- Plain Unicode string
- The actual data
- The text of the selection
Otherwise, if any files are being dragged, then add one item per file to the drag data store item list, with their properties set as follows:
- The drag data item type string
- The MIME type of the file, if known, or "
application/octet-stream
" otherwise. - The drag data item kind
- File
- The actual data
- The file’s contents and name.
Dragging files can currently only happen from outside a browsing context, for example from a file system manager application.
If the drag initiated outside of the application, the user agent must add items to the drag data store item list as appropriate for the data being dragged, honoring platform conventions where appropriate; however, if the platform conventions do not use MIME types to label dragged data, the user agent must make a best-effort attempt to map the types to MIME types, and, in any case, all the drag data item type strings must be converted to ASCII lowercase.
User agents may also add one or more items representing the selection or dragged element(s) in other forms, e.g., as HTML.
-
If the list of dragged nodes is not empty, then extract the microdata from those nodes into a JSON form, and add one item to the drag data store item list, with its properties set as follows:
- The drag data item type string
application/microdata+json
- The drag data item kind
- Plain Unicode string
- The actual data
- The resulting JSON string.
-
Run the following substeps:
- Let urls be an empty list of absolute URLs.
-
For each node in the list of dragged nodes:
- If urls is still empty, abort these substeps.
- Let url string be the result of concatenating the strings in urls, in the order they were added, separated by a U+000D CARRIAGE RETURN U+000A LINE FEED character pair (CRLF).
-
Add one item to the drag data store item list, with its properties set as
follows:
- The drag data item type string
text/uri-list
- The drag data item kind
- Plain Unicode string
- The actual data
- url string
-
Update the drag data store default feedback as appropriate for the user agent (if the user is dragging the selection, then the selection would likely be the basis for this feedback; if the user is dragging an element, then that element’s rendering would be used; if the drag began outside the user agent, then the platform conventions for determining the drag feedback should be used).
-
Fire a DND event named
dragstart
at the source node.If the event is canceled, then the drag-and-drop operation should not occur; abort these steps.
Since events with no event listeners registered are, almost by definition, never canceled, drag-and-drop is always available to the user if the author does not specifically prevent it.
-
Initiate the drag-and-drop operation in a manner consistent with platform conventions, and as described below.
The drag-and-drop feedback must be generated from the first of the following sources that is available:
- The drag data store bitmap, if any. In this case, the drag data store hot spot coordinate should be used as hints for where to put the cursor relative to the resulting image. The values are expressed as distances in CSS pixels from the left side and from the top side of the image respectively. [CSS-2015]
- The drag data store default feedback.
From the moment that the user agent is to initiate the drag-and-drop operation, until the end of the drag-and-drop operation, device input events (e.g., mouse and keyboard events) must be suppressed.
During the drag operation, the element directly indicated by the user as the drop target is called the immediate user selection. (Only elements can be selected by the user; other nodes must not be made available as drop targets.) However, the immediate user selection is not necessarily the current target element, which is the element currently selected for the drop part of the drag-and-drop operation.
The immediate user selection changes as the user selects different elements (either by pointing at them with a pointing device, or by selecting them in some other way). The current target element changes when the immediate user selection changes, based on the results of event listeners in the document, as described below.
Both the current target element and the immediate user selection can be null, which means no target element is selected. They can also both be elements in other (DOM-based) documents, or other (non-Web) programs altogether. (For example, a user could drag text to a word-processor.) The current target element is initially null.
In addition, there is also a current drag operation, which can take on the values
"none
", "copy
", "link
", and "move
". Initially, it has the value
"none
". It is updated by the user agent
as described in the steps below.
User agents must, as soon as the drag operation is initiated and every 350ms (±200ms) thereafter for as long as the drag operation is ongoing, queue a task to perform the following steps in sequence:
-
If the user agent is still performing the previous iteration of the sequence (if any) when the next iteration becomes due, abort these steps for this iteration (effectively "skipping missed frames" of the drag-and-drop operation).
-
Fire a DND event named
drag
at the source node. If this event is canceled, the user agent must set the current drag operation to "none
" (no drag operation). -
If the
drag
event was not canceled and the user has not ended the drag-and-drop operation, check the state of the drag-and-drop operation, as follows:-
If the user is indicating a different immediate user selection than during the last iteration (or if this is the first iteration), and if this immediate user selection is not the same as the current target element, then fire a DND event named
dragexit
at the current target element, and then update the current target element as follows:- If the new immediate user selection is null
- Set the current target element to null also.
- If the new immediate user selection is in a non-DOM document or application
- Set the current target element to the immediate user selection.
- Otherwise
-
Fire a DND event named
dragenter
at the immediate user selection.If the event is canceled, then set the current target element to the immediate user selection.
Otherwise, run the appropriate step from the following list:
- If the immediate user selection is a text field (e.g.,
textarea
, or aninput
element whosetype
attribute is in the Text state) or an editing host or editable element, and the drag data store item list has an item with the drag data item type string "text/plain
" and the drag data item kind Plain Unicode string - Set the current target element to the immediate user selection anyway.
- If the immediate user selection is an element with a
dropzone
attribute that matches the drag data store - Set the current target element to the immediate user selection anyway.
- If the immediate user selection is an element that itself has an ancestor
element with a
dropzone
attribute that matches the drag data store -
Let new target be the nearest (deepest) such ancestor element.
If the immediate user selection is new target, then leave the current target element unchanged.
Otherwise, fire a DND event named
dragenter
at new target, with the current current target element as the specific related target. Then, set the current target element to new target, regardless of whether that event was canceled or not. - If the immediate user selection is the
body
element - Leave the current target element unchanged.
- Otherwise
-
Fire a DND event named
dragenter
at thebody
element, if there is one, or at theDocument
object, if not. Then, set the current target element to thebody
element, regardless of whether that event was canceled or not.
- If the immediate user selection is a text field (e.g.,
-
If the previous step caused the current target element to change, and if the previous target element was not null or a part of a non-DOM document, then fire a DND event named
dragleave
at the previous target element, with the new current target element as the specific related target. -
If the current target element is a DOM element, then fire a DND event named
dragover
at this current target element.If the
dragover
event is not canceled, run the appropriate step from the following list:- If the current target element is a text field (e.g.,
textarea
, or aninput
element whosetype
attribute is in the Text state) or an editing host or editable element, and the drag data store item list has an item with the drag data item type string "text/plain
" and the drag data item kind Plain Unicode string - Set the current drag operation to either "
copy
" or "move
", as appropriate given the platform conventions. - If the current target element is an element with a
dropzone
attribute that matches the drag data store and specifies an operation - Set the current drag operation to the operation specified by the
dropzone
attribute of the current target element. - If the current target element is an element with a
dropzone
attribute that matches the drag data store and does not specify an operation - Set the current drag operation to "
copy
". - Otherwise
- Reset the current drag operation to "
none
".
Otherwise (if the
dragover
event is canceled), set the current drag operation based on the values of theeffectAllowed
anddropEffect
attributes of theDragEvent
object’sdataTransfer
object as they stood after the event dispatch finished, as per the following table:effectAllowed
dropEffect
Drag operation " uninitialized
", "copy
", "copyLink
", "copyMove
", or "all
"" copy
"" copy
"" uninitialized
", "link
", "copyLink
", "linkMove
", or "all
"" link
"" link
"" uninitialized
", "move
", "copyMove
", "linkMove
", or "all
"" move
"" move
"Any other case " none
" - If the current target element is a text field (e.g.,
-
Otherwise, if the current target element is not a DOM element, use platform-specific mechanisms to determine what drag operation is being performed (none, copy, link, or move), and set the current drag operation accordingly.
-
Update the drag feedback (e.g., the mouse cursor) to match the current drag operation, as follows:
Drag operation Feedback " copy
"Data will be copied if dropped here. " link
"Data will be linked if dropped here. " move
"Data will be moved if dropped here. " none
"No operation allowed, dropping here will cancel the drag-and-drop operation.
-
-
Otherwise, if the user ended the drag-and-drop operation (e.g., by releasing the mouse button in a mouse-driven drag-and-drop interface), or if the
drag
event was canceled, then this will be the last iteration. Run the following steps, then stop the drag-and-drop operation:-
If the current drag operation is "
none
" (no drag operation), or, if the user ended the drag-and-drop operation by canceling it (e.g., by hitting the Escape key), or if the current target element is null, then the drag operation failed. Run these substeps:- Let dropped be false.
- If the current target element is a DOM element, fire a DND
event named
dragleave
at it; otherwise, if it is not null, use platform-specific conventions for drag cancelation. - Set the current drag operation to "
none
".
Otherwise, the drag operation might be a success; run these substeps:
- Let dropped be true.
- If the current target element is a DOM element, fire a DND
event named
drop
at it; otherwise, use platform-specific conventions for indicating a drop. -
If the event is canceled, set the current drag operation to the value of the
dropEffect
attribute of theDragEvent
object’sdataTransfer
object as it stood after the event dispatch finished.Otherwise, the event is not canceled; perform the event’s default action, which depends on the exact target as follows:
- If the current target element is a text field (e.g.,
textarea
, or aninput
element whosetype
attribute is in the Text state) or an editing host or editable element, and the drag data store item list has an item with the drag data item type string "text/plain
" and the drag data item kind Plain Unicode string - Insert the actual data of the first item in the drag data store item
list to have a drag data item type
string of "
text/plain
" and a drag data item kind that is Plain Unicode string into the text field or editing host or editable element in a manner consistent with platform-specific conventions (e.g., inserting it at the current mouse cursor position, or inserting it at the end of the field). - Otherwise
- Reset the current drag operation to "
none
".
- If the current target element is a text field (e.g.,
-
Fire a DND event named
dragend
at the source node. -
Run the appropriate steps from the following list as the default action of the
dragend
event:- If dropped is true, the current target element is a text
field (see below), the current drag operation is "
move
", and the source of the drag-and-drop operation is a selection in the DOM that is entirely contained within an editing host - Delete the selection.
- If dropped is true, the current target element is a text
field (see below), the current drag operation is "
move
", and the source of the drag-and-drop operation is a selection in a text field - The user agent should delete the dragged selection from the relevant text field.
- If dropped is false or if the current drag operation is "
none
" - The drag was canceled. If the platform conventions dictate that this be represented to the user (e.g., by animating the dragged selection going back to the source of the drag-and-drop operation), then do so.
- Otherwise
- The event has no default action.
For the purposes of this step, a text field is a
textarea
element or aninput
element whosetype
attribute is in one of the Text, Search, Telephone, URL, E-mail, Password, or Number states. - If dropped is true, the current target element is a text
field (see below), the current drag operation is "
-
User agents are encouraged to consider how to react to drags near the edge of scrollable regions. For example, if a user drags a link to the bottom of the viewport on a long page, it might make sense to scroll the page so that the user can drop the link lower on the page.
This model is independent of which Document
object the nodes involved are from;
the events are fired as described above and the rest of the processing model runs as described
above, irrespective of how many documents are involved in the operation.
5.7.6. Events summary
This section is non-normative.
The following events are involved in the drag-and-drop model.
Event Name | Target | Cancelable? | Drag data store mode | dropEffect
| Default Action |
---|---|---|---|---|---|
dragstart
| Source node | ✓ Cancelable | Read/write mode | "none "
| Initiate the drag-and-drop operation |
drag
| Source node | ✓ Cancelable | Protected mode | "none "
| Continue the drag-and-drop operation |
dragenter
| Immediate user selection or the body element
| ✓ Cancelable | Protected mode | Based on effectAllowed value
| Reject immediate user selection as potential target element |
dragexit
| Previous target element | — | Protected mode | "none "
| None |
dragleave
| Previous target element | — | Protected mode | "none "
| None |
dragover
| Current target element | ✓ Cancelable | Protected mode | Based on effectAllowed value
| Reset the current drag operation to "none" |
drop
| Current target element | ✓ Cancelable | Read-only mode | Current drag operation | Varies |
dragend
| Source node | — | Protected mode | Current drag operation | Varies |
Not shown in the above table: all these events bubble, and the effectAllowed
attribute always has the value it had after the dragstart
event, defaulting to
"uninitialized
" in the dragstart
event.
5.7.7. The draggable
attribute
All html elements may have the draggable
content attribute set. The draggable
attribute is an enumerated attribute. It has three states. The first
state is true and it has the keyword true
. The second state is false and it has the keyword false
. The third state is auto; it has no keywords but
it is the missing value default.
The true state means the element is draggable; the false state means that it is not. The auto state uses the default behavior of the user agent.
An element with a draggable
attribute should also have a title
attribute
that names the element for the purpose of non-visual interactions.
- element .
draggable
[ = value ] -
Returns true if the element is draggable; otherwise, returns false.
Can be set, to override the default and set the
draggable
content attribute.
The draggable
IDL attribute, whose value depends on the content
attribute’s in the way described below, controls whether or not the element is draggable.
Generally, only text selections are draggable, but elements whose draggable
IDL
attribute is true become draggable as well.
If an element’s draggable
content attribute has the state true, the draggable
IDL attribute must return true.
Otherwise, if the element’s draggable
content attribute has the state false,
the draggable
IDL attribute must return false.
Otherwise, the element’s draggable
content attribute has the state auto. If
the element is an img
element, an object
element that represents an image, or an a
element with an href
content
attribute, the draggable
IDL attribute must return true; otherwise, the draggable
IDL attribute must return false.
If the draggable
IDL attribute is set to the value false, the draggable
content attribute must be set to the literal value "false
".
If the draggable
IDL attribute is set to the value true, the draggable
content attribute must be set to the literal value "true
".
5.7.8. The dropzone
attribute
All html elements may have the dropzone
content attribute set. When specified,
its value must be an unordered set of unique space-separated tokens that are ASCII case-insensitive. The allowed values are the following:
-
Indicates that dropping an accepted item on the element will result in a copy of the dragged data.
-
Indicates that dropping an accepted item on the element will result in the dragged data being moved to the new location.
-
link
-
Indicates that dropping an accepted item on the element will result in a link to the original data.
-
Any keyword with eight characters or more, beginning with an ASCII case-insensitive match for the string "
string:
" -
Indicates that items with the drag data item kind Plain Unicode string and the drag data item type string set to a value that matches the remainder of the keyword are accepted.
-
Any keyword with six characters or more, beginning with an ASCII case-insensitive match for the string "
file:
" -
Indicates that items with the drag data item kind File and the drag data item type string set to a value that matches the remainder of the keyword are accepted.
The dropzone
content attribute’s values must not have more than one of the three
feedback values (copy
, move
, and link
) specified. If none
are specified, the copy
value is implied.
An element with a dropzone
attribute should also have a title
attribute
that names the element for the purpose of non-visual interactions.
dropzone
attribute matches a drag data store if the dropzone
processing steps result in a match.
A dropzone
attribute specifies an operation if the dropzone
processing steps result in a specified operation. The specified
operation is as given by those steps.
The dropzone
processing steps are as follows. They either result in a
match or not, and separate from this result either in a specified operation or not, as defined
below.
-
Let value be the value of the
dropzone
attribute. -
Let keywords be the result of splitting value on spaces.
-
Let matched be false.
-
Let operation be unspecified.
-
For each value in keywords, if any, in the order that they were found in value, run the following steps.
-
Let keyword be the keyword.
-
If keyword is one of "
copy
", "move
", or "link
", then: run the following substeps:-
If operation is still unspecified, then let operation be the string given by keyword.
-
Skip to the step labeled end of keyword below.
-
-
If keyword does not contain a U+003A COLON character (:), or if the first such character in keyword is either the first character or the last character in the string, then skip to the step labeled end of keyword below.
-
Let kind code be the substring of keyword from the first character in the string to the last character in the string that is before the first U+003A COLON character (:) in the string, converted to ASCII lowercase.
-
Jump to the appropriate step from the list below, based on the value of kind code:
- If kind code is the string "
string
" - Let kind be Plain Unicode string.
- If kind code is the string "
file
" - Let kind be File.
- Otherwise
- Skip to the step labeled end of keyword below.
- If kind code is the string "
-
Let type be the substring of keyword from the first character after the first U+003A COLON character (:) in the string, to the last character in the string, converted to ASCII lowercase.
-
If there exist any items in the drag data store item list whose drag data item kind is the kind given in kind and whose drag data item type string is type, then let matched be true.
-
End of keyword: Go on to the next keyword, if any, or the next step in the overall algorithm, if there are no more.
-
-
The algorithm results in a match if matched is true, and does not otherwise.
The algorithm results in a specified operation if operation is not unspecified. The specified operation, if one is specified, is the one given by operation.
The dropzone
IDL attribute must reflect the content attribute of
the same name.
The supported tokens for dropzone
are the allowed values defined for the dropzone
attribute that are supported by the user agent.
div
element is made into a drop target for image files using the dropzone
attribute. Images dropped into the target are then displayed.
<div dropzone="copy file:image/png file:image/gif file:image/jpeg" ondrop="receive(event, this)"> <p>Drop an image here to have it displayed.</p> </div> <script> function receive(event, element) { var data = event.dataTransfer.items; for (var i = 0; i < data.length; i += 1) { if ((data[i].kind == 'file') && (data[i].type.match('^image/'))) { var img = new Image(); img.src = window.createObjectURL(data[i].getAsFile()); element.appendChild(img); } } } </script>
5.7.9. Security risks in the drag-and-drop model
User agents must not make the data added to the DataTransfer
object during the dragstart
event available to scripts until the drop
event, because
otherwise, if a user were to drag sensitive information from one document to a second document,
crossing a hostile third document in the process, the hostile document could intercept the data.
For the same reason, user agents must consider a drop to be successful only if the user
specifically ended the drag operation — if any scripts end the drag operation, it must be
considered unsuccessful (canceled) and the drop
event must not be fired.
User agents should take care to not start drag-and-drop operations in response to script actions. For example, in a mouse-and-window environment, if a script moves a window while the user has his mouse button depressed, the user agent would not consider that to start a drag. This is important because otherwise user agents could cause data to be dragged from sensitive sources and dropped into hostile documents without the user’s consent.
User agents should filter potentially active (scripted) content (e.g., HTML) when it is dragged and when it is dropped, using a safelist of known-safe features. Similarly, relative URLs should be turned into absolute URLs to avoid references changing in unexpected ways. This specification does not specify how this is performed.
contenteditable
region. If the browser does not ensure that only safe content is dragged, potentially unsafe
content such as scripts and event handlers in the selection, once dropped (or pasted) into the
victim site, get the privileges of the victim site. This would thus enable a cross-site
scripting attack. 6. Loading Web pages
This section describes features that apply most directly to Web browsers. Having said that, except where specified otherwise, the requirements defined in this section do apply to all user agents, whether they are Web browsers or not.
6.1. Browsing contexts
A browsing context is an environment in which Document
objects are presented to the user.
A tab or window in a Web browser typically contains a browsing context, as
does an iframe
or frame
s in a frameset
.
A browsing context has a corresponding WindowProxy
object.
A browsing context has a session history, which lists the Document
objects that the browsing context has presented, is
presenting, or will present. At any time, one Document
in each browsing context is designated the active document. A Document
's browsing context is that browsing context whose session
history contains the Document
, if any. (A Document
created using
an API such as createDocument()
has no browsing context.) Each Document
in a browsing context is associated with
a Window
object.
In general, there is a 1-to-1 mapping from the Window
object to the Document
object. There are two exceptions. First, a Window
can be reused
for the presentation of a second Document
in the same browsing context,
such that the mapping is then 1-to-2. This occurs when a browsing context is navigated from the initial about:blank
Document
to another, with replacement enabled. Second, a Document
can end up
being reused for several Window
objects when the document.open()
method is
used, such that the mapping is then many-to-1.
A Document
does not necessarily have a browsing context associated with it. In particular, data mining tools are likely to never instantiate browsing
contexts.
A browsing context can have a creator browsing context, the browsing context that was responsible for its creation. If a browsing context has a parent browsing context, then that is its creator browsing context. Otherwise, if the browsing context has an opener browsing context, then that is its creator browsing context. Otherwise, the browsing context has no creator browsing context.
If a browsing context A has a creator browsing context, then the creator origin, creator URL, and creator base URL are the origin, URL, and base URL, respectively, of
the Document
that was the active document of that creator browsing context at
the time A was created.
To create a new browsing context:
-
Call the JavaScript InitializeHostDefinedRealm() abstract operation with the following customizations:
-
For the global object, create a new
Window
object window. -
For the global this value, create a new
WindowProxy
object windowProxy, whose [[Window
]] internal slot value is window.The internal slot value is updated when navigations occur.
-
Let realm execution context be the created JavaScript execution context.
-
-
Set the new browsing context’s associated
WindowProxy
to windowProxy. -
Let document be a new
Document
, whose URL is about:blank, which is marked as being an HTML document, whose character encoding is UTF-8, and which is both ready for post-load tasks and completely loaded immediately. -
Set the origin of document:
-
If the new browsing context has a creator browsing context, then the origin of document is the creator origin.
-
Otherwise, the origin of document is a unique opaque origin assigned when the new browsing context is created.
-
-
If the new browsing context has a creator browsing context, then set document’s referrer to the creator URL.
-
Ensure that document has a single child
html
node, which itself has two empty child nodes: ahead
element, and abody
element. -
Implement the sandboxing for document.
-
Add document to the new browsing context’s session history.
-
Set window’s associated
Document
to document. -
Set up a browsing context environment settings object with realm execution context.
6.1.1. Nested browsing contexts
Certain elements (for example, iframe
elements) can instantiate further browsing contexts. These are called nested browsing contexts. If a browsing context P has a Document
D with an element E that nests
another browsing context C inside it, then C is said to be nested through D, and E is said to be the browsing context container of C.
If the browsing context container element E is in the Document
D, then P is
said to be the parent browsing context of C and C is said to be a child browsing context of P.
Otherwise, the nested browsing context C has no parent
browsing context.
A browsing context A is said to be an ancestor of a browsing context B if there exists a browsing context A that is a child browsing context of A and that is itself an ancestor of B, or if the browsing context A is the parent browsing context of B.
A browsing context that is not a nested browsing context has no parent browsing context, and is the top-level browsing context of all the browsing contexts for which it is an ancestor browsing context.
The transitive closure of parent browsing contexts for a nested browsing context gives the list of ancestor browsing contexts.
The list of the descendant browsing contexts of a Document
d is the (ordered) list returned by the following algorithm:
- Let list be an empty list.
-
For each child browsing context of d that is nested through an element that is in the
Document
d, in the tree order of the elements nesting those browsing contexts, run these substeps:- Append that child browsing context to the list list.
- Append the list of the descendant browsing contexts of the active document of that child browsing context to the list list.
- Return the constructed list.
A Document
is said to be fully active when it has a browsing context and it is the active document of
that browsing context, and either its browsing context is a top-level browsing context, or it has a parent browsing context and the Document
through which it is nested is itself fully active.
Because they are nested through an element, child browsing contexts are always tied to a
specific Document
in their parent browsing context. User agents must not allow the user
to interact with child browsing contexts of elements that are in Document
s that are
not themselves fully active.
A nested browsing context can be put into a delaying load
events mode. This is used when it is navigated, to delay the load event of the browsing
context container before the new Document
is created.
The document family of a browsing context consists of the union of all
the Document
objects in that browsing context’s session
history and the document families of all those Document
objects. The document family of a Document
object
consists of the union of all the document families of the browsing contexts that are nested through the Document
object.
6.1.1.1. Navigating nested browsing contexts in the DOM
- window .
top
-
Returns the
WindowProxy
for the top-level browsing context. - window .
parent
-
Returns the
WindowProxy
for the parent browsing context. - window .
frameElement
-
Returns the
Element
for the browsing context container.Returns null if there isn’t one, and in cross-origin situations.
The top
IDL attribute on the Window
object
of a Document
in a browsing context b must return
the WindowProxy
object of its top-level browsing context (which would be
its own WindowProxy
object if it was a top-level browsing context itself), if it has one, or its own WindowProxy
object otherwise (e.g., if it was a
detached nested browsing context).
The parent
IDL attribute on the Window
object
of a Document
that has a browsing context b must return the WindowProxy
object of the parent browsing context, if there is one (i.e., if b is a child browsing context), or the WindowProxy
object of the browsing context b itself, otherwise (i.e., if it is a top-level browsing context or a detached nested browsing context).
The frameElement
IDL attribute, on getting, must
run the following algorithm:
-
Let d be the
Window
object’s associatedDocument
. -
Let context be d’s browsing context.
-
If context is not a nested browsing context, return null and abort these steps.
-
Let container be context’s browsing context container.
-
If container’s node document’s origin is not same origin-domain with the entry settings object’s origin, then return null and abort these steps.
-
Return container.
6.1.2. Auxiliary browsing contexts
It is possible to create new browsing contexts that are related to a top-level browsing context without being nested through an element. Such browsing contexts are called auxiliary browsing contexts. Auxiliary browsing contexts are always top-level browsing contexts.
An auxiliary browsing context has an opener browsing context, which is the browsing context from which the auxiliary browsing context was created.
6.1.2.1. Navigating auxiliary browsing contexts in the DOM
The opener
IDL attribute on the Window
object, on getting, must return the WindowProxy
object of the browsing
context from which the current browsing context was created (its opener
browsing context), if there is one, if it is still available, and if the current browsing context has not disowned its opener;
otherwise, it must return null. On setting, if the new value is null then the current browsing context must disown its opener; if
the new value is anything else then the user agent must
call the [[DefineOwnProperty]] internal method of the Window
object, passing the
property name "opener
" as the property key, and the Property Descriptor {
[[Value]]: value, [[Writable]]: true, [[Enumerable]]: true,
[[Configurable]]: true } as the property descriptor,
where value is the new value.
6.1.3. Security
A browsing context A is familiar with a second browsing context B if one of the following conditions is true:
- Either the origin of the active document of A is the same as the origin of the active document of B, or
- The browsing context A is a nested browsing context with a top-level browsing context, and its top-level browsing context is B, or
- The browsing context B is an auxiliary browsing context and A is familiar with B’s opener browsing context, or
- The browsing context B is not a top-level browsing context, but there exists an ancestor browsing context of B whose active document has the same origin as the active document of A (possibly in fact being A itself).
A browsing context A is allowed to navigate a second browsing context B if the following algorithm terminates positively:
- If A is not the same browsing context as B, and A is not one of the ancestor browsing contexts of B, and B is not a top-level browsing context, and A’s active document’s active sandboxing flag set has its sandboxed navigation browsing context flag set, then abort these steps negatively.
- Otherwise, if B is a top-level browsing context, and is one of the ancestor browsing contexts of A, and A’s active document’s active sandboxing flag set has its sandboxed top-level navigation browsing context flag set, then abort these steps negatively.
- Otherwise, if B is a top-level browsing context, and is
neither A nor one of the ancestor
browsing contexts of A, and A’s
Document
's active sandboxing flag set has its sandboxed navigation browsing context flag set, and A is not the one permitted sandboxed navigator of B, then abort these steps negatively. - Otherwise, terminate positively!
An element has a browsing context scope origin if its Document
's browsing context is a top-level browsing context or if all of its Document
's ancestor browsing contexts all have active documents whose origin are the same origin as the element’s node document’s origin. If an
element has a browsing context scope origin, then its value is the origin of the element’s node document.
6.1.4. Groupings of browsing contexts
Each browsing context is defined as having a list of one or more directly reachable browsing contexts. These are:
-
The browsing context itself.
-
All the browsing context’s child browsing contexts.
-
All the browsing contexts that have the browsing context as their opener browsing context.
The transitive closure of all the browsing contexts that are directly reachable browsing contexts forms a unit of related browsing contexts.
Each unit of related browsing contexts is then further divided into the smallest number of
groups such that every member of each group has an active document with an origin that, through appropriate manipulation of the document.domain
attribute, could be made to be same origin-domain with
other members of the group, but could not be made the same as members of any other group. Each
such group is a unit of related similar-origin browsing contexts.
There is also at most one event loop per unit of related similar-origin browsing contexts (though several units of related similar-origin browsing contexts can have a shared event loop).
6.1.5. Browsing context names
Browsing contexts can have a browsing context name. By default, a browsing context has no name (its name is not set).
A valid browsing context name is any string with at least one character that does not start with a U+005F LOW LINE character. (Names starting with an underscore are reserved for special keywords.)
A valid browsing context name or keyword is any string that is either a valid
browsing context name or that is an ASCII case-insensitive match for one of: _blank
, _self
, _parent
, or _top
.
These values have different meanings based on whether the page is sandboxed or not, as summarized
in the following (non-normative) table. In this table, "current" means the browsing context that the link or script is in, "parent" means the parent browsing context of the one the
link or script is in, "top" means the top-level browsing context of the one the link or
script is in, "new" means a new top-level browsing context or auxiliary browsing context is to be created, subject to various user preferences and user
agent policies, "none" means that nothing will happen, and "maybe new" means the same as "new" if
the "allow-popups
" keyword is also specified on the sandbox
attribute
(or if the user overrode the sandboxing), and the same as "none" otherwise.
Keyword | Ordinary effect | Effect in an iframe with...
| |
---|---|---|---|
sandbox=""
| sandbox="allow-top-navigation"
| ||
none specified, for links and form submissions | current | current | current |
empty string | current | current | current |
_blank
| new | maybe new | maybe new |
_self
| current | current | current |
_parent if there isn’t a parent
| current | current | current |
_parent if parent is also top
| parent/top | none | parent/top |
_parent if there is one and it’s not top
| parent | none | none |
_top if top is current
| current | current | current |
_top if top is not current
| top | none | top |
name that doesn’t exist | new | maybe new | maybe new |
name that exists and is a descendant | specified descendant | specified descendant | specified descendant |
name that exists and is current | current | current | current |
name that exists and is an ancestor that is top | specified ancestor | none | specified ancestor/top |
name that exists and is an ancestor that is not top | specified ancestor | none | none |
other name that exists with common top | specified | none | none |
name that exists with different top, if familiar and one permitted sandboxed navigator | specified | specified | specified |
name that exists with different top, if familiar but not one permitted sandboxed navigator | specified | none | none |
name that exists with different top, not familiar | new | maybe new | maybe new |
Most of the restrictions on sandboxed browsing contexts are applied by other algorithms, e.g., the navigation algorithm, not the rules for choosing a browsing context given a browsing context name given below.
An algorithm is allowed to show a popup if any of the following conditions is true:
- The task in which the algorithm is running is currently
processing an activation behavior whose
click
event was trusted. -
The task in which the algorithm is running is currently running the event listener for a trusted event whose type is in the following list:
change
click
dblclick
mouseup
reset
submit
-
The task in which the algorithm is running was queued by an algorithm that was allowed to show a popup, and the chain of such algorithms started within a user-agent defined timeframe.
For example, if a user clicked a button, it might be acceptable for a popup to result from that after 4 seconds, but it would likely not be acceptable for a popup to result from that after 4 hours.
The rules for choosing a browsing context given a browsing context name are as follows. The rules assume that they are being applied in the context of a browsing context, as part of the execution of a task.
- If the given browsing context name is the empty string or
_self
, then the chosen browsing context must be the current one. - If the given browsing context name is
_parent
, then the chosen browsing context must be the parent browsing context of the current one, unless there isn’t one, in which case the chosen browsing context must be the current browsing context. - If the given browsing context name is
_top
, then the chosen browsing context must be the top-level browsing context of the current one, if there is one, or else the current browsing context. - If the given browsing context name is not
_blank
and there exists a browsing context whose name is the same as the given browsing context name, and the current browsing context is familiar with that browsing context, and the user agent determines that the two browsing contexts are related enough that it is ok if they reach each other, then that browsing context must be the chosen one. If there are multiple matching browsing contexts, the user agent should select one in some arbitrary consistent manner, such as the most recently opened, most recently focused, or more closely related. -
Otherwise, a new browsing context is being requested, and what happens depends on the user
agent’s configuration and abilities — it is determined by the rules given for the first
applicable option from the following list:
- If the algorithm is not allowed to show a popup and the user agent has been configured to not show popups (i.e., the user agent has a "popup blocker" enabled)
-
There is no chosen browsing context. The user agent may inform the user that a popup has been blocked.
- If the current browsing context’s active document’s active sandboxing flag set has the sandboxed auxiliary navigation browsing context flag set.
-
Typically, there is no chosen browsing context.
The user agent may offer to create a new top-level browsing context or reuse an existing top-level browsing context. If the user picks one of those options, then the designated browsing context must be the chosen one (the browsing context’s name isn’t set to the given browsing context name). The default behavior (if the user agent doesn’t offer the option to the user, or if the user declines to allow a browsing context to be used) must be that there must not be a chosen browsing context.
If this case occurs, it means that an author has explicitly sandboxed the document that is trying to open a link.
- If the user agent has been configured such that in this instance it will
create a new browsing context, and the browsing context is being requested as part of following a hyperlink whose link
types include the
noreferrer
keyword -
A new top-level browsing context must be created. If the given browsing
context name is not
_blank
, then the new top-level browsing context’s name must be the given browsing context name (otherwise, it has no name). The chosen browsing context must be this new browsing context. The creation of such a browsing context is a new start for session storage.If it is immediately navigated, then the navigation will be done with replacement enabled.
- If the user agent has been configured such that in this instance it will create a new
browsing context, and the
noreferrer
keyword doesn’t apply -
A new auxiliary browsing context must be created, with the opener
browsing context being the current one. If the given browsing context name is not
_blank
, then the new auxiliary browsing context’s name must be the given browsing context name (otherwise, it has no name). The chosen browsing context must be this new browsing context.If it is immediately navigated, then the navigation will be done with replacement enabled.
- If the user agent has been configured such that in this instance it will reuse the current browsing context
- The chosen browsing context is the current browsing context.
- If the user agent has been configured such that in this instance it will not find a browsing context
- There must not be a chosen browsing context.
User agent implementors are encouraged to provide a way for users to configure the user agent to always reuse the current browsing context.
If the current browsing context’s active document’s active sandboxing flag set has both the sandboxed navigation browsing context flag and sandbox propagates to auxiliary browsing contexts flag set, and the chosen browsing context picked above, if any, is a new browsing context, then all the flags that are set in the current browsing context’s active document’s active sandboxing flag set when the new browsing context is created must be set in the new browsing context’s popup sandboxing flag set, and the current browsing context must be set as the new browsing context’s one permitted sandboxed navigator.
6.1.6. Script settings for browsing contexts
When the user agent is required to set up a browsing context environment settings object, given a JavaScript execution context execution context, it must run the following steps:
-
Let realm be the value of execution context’s Realm component.
-
Let window be realm’s global object.
-
Let url be a copy of the URL of the
Document
with which window is associated. -
Let settings object be a new environment settings object whose algorithms are defined as follows:
-
Return execution context.
-
Return the browsing context with which window is associated.
-
Return the event loop that is associated with the unit of related similar-origin browsing contexts to which window’s browsing context belongs.
-
Return the
Document
with which window is currently associated. -
Return the current character encoding of the
Document
with which window is currently associated. -
The API base URL
-
Return the current base URL of the
Document
with which window is currently associated. -
The origin
-
Return the origin of the
Document
with which window is currently associated. -
The creation URL
-
Return url.
-
The HTTPS state
-
Return the HTTPS state of the
Document
with which window is currently associated.
-
Set realm’s [[HostDefined]] field to settings object.
-
Return settings object.
6.2. Security infrastructure for Window
, WindowProxy
, and Location
objects
Although typically objects cannot be accessed across origins, the web platform would not be true to itself if it did not have some legacy exceptions to that rule that the web depends upon.
6.2.1. Integration with IDL
When perform a security check is invoked, with a platformObject, realm, identifier, and type, run these steps:
-
If platformObject is a
Window
orLocation
object, then:-
Repeat for each e that is an element of CrossOriginProperties(platformObject):
-
If SameValue(e.[[Property]], identifier) is true, then:
-
If type is "
method
" and e has neither [[NeedsGet]] nor [[NeedsGet]], then return. -
Otherwise, if type is "
getter
" and e.[[NeedsGet]] is true, then return. -
Otherwise, if type is "
setter
" and e.[[NeedsSet]] is true, then return.
-
-
-
-
If IsPlatformObjectSameOrigin(platformObject) is false, then throw a "
SecurityError
"DOMException
.
6.2.2. Shared internal slot: [[CrossOriginPropertyDescriptorMap]]
Window
and Location
objects both have a [[CrossOriginPropertyDescriptorMap]]
internal slot, whose value is initially an empty map.
The [[CrossOriginPropertyDescriptorMap]] internal slot contains a map with
entries whose keys are (currentOrigin, objectOrigin, propertyKey)-tuples and values are property
descriptors, as a memoization of what is visible to scripts when currentOrigin inspects a Window
or Location
object from objectOrigin. It is filled lazily by CrossOriginGetOwnPropertyHelper, which consults it on future lookups.
User agents should allow a value held in the map to be garbage collected along with its corresponding key when nothing holds a reference to any part of the value. That is, as long as garbage collection is not observable.
const href = Object.getOwnPropertyDescriptor(crossOriginLocation, "href").set
the value and its corresponding key in the map cannot be garbage collected as that would be observable.
User agents may have an optimization whereby they remove key-value pairs from the map when document.domain
is set. This is not observable as document.domain
cannot revisit an earlier value.
document.domain
to "example.com
" on www.example.com
means user agents can remove all key-value pairs from the map where
part of the key is www.example.com
, as that can never be part of the origin again and
therefore the corresponding value could never be retrieved from the map. 6.2.3. Shared abstract operations
6.2.3.1. CrossOriginProperties ( O )
-
Assert: O is a
2. If O is aLocation
orWindow
object.Location
object, then return« { [[Property]]: "href", [[NeedsGet]]: false, [[NeedsSet]]: true }, { [[Property]]: "replace" } »
3. Let crossOriginWindowProperties be« { [[Property]]: "window", [[NeedsGet]]: true, [[NeedsSet]]: false }, { [[Property]]: "self", [[NeedsGet]]: true, [[NeedsSet]]: false }, { [[Property]]: "location", [[NeedsGet]]: true, [[NeedsSet]]: true }, { [[Property]]: "close" }, { [[Property]]: "closed", [[NeedsGet]]: true, [[NeedsSet]]: false }, { [[Property]]: "focus" }, { [[Property]]: "blur" }, { [[Property]]: "frames", [[NeedsGet]]: true, [[NeedsSet]]: false }, { [[Property]]: "length", [[NeedsGet]]: true, [[NeedsSet]]: false }, { [[Property]]: "top", [[NeedsGet]]: true, [[NeedsSet]]: false }, { [[Property]]: "opener", [[NeedsGet]]: true, [[NeedsSet]]: false }, { [[Property]]: "parent", [[NeedsGet]]: true, [[NeedsSet]]: false }, { [[Property]]: "postMessage" } »
-
Repeat for each e that is an element of the child browsing context name property set:
-
Add { [[Property]]: e } as the last element of crossOriginWindowProperties.
-
-
Return crossOriginWindowProperties.
Indexed properties do not need to be safelisted as they are handled directly by
the WindowProxy
object.
6.2.3.2. IsPlatformObjectSameOrigin ( O )
-
Return true if the current settings object’s origin is same origin-domain with O’s relevant settings object’s origin, and false otherwise.
6.2.3.3. CrossOriginGetOwnPropertyHelper ( O, P )
If this abstract operation returns undefined and there is no custom behavior, the
caller needs to throw a "SecurityError
" DOMException
.
-
If P is @@toStringTag, @@hasInstance, or @@isConcatSpreadable, then return PropertyDescriptor { [[Value]]: undefined, [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
-
Let crossOriginKey be a tuple consisting of the current settings object’s origin’s effective domain, O’s relevant settings object’s origin’s effective domain, and P.
-
Repeat for each e that is an element of CrossOriginProperties(O):
-
If SameValue(e.[[Property]], P) is true, then:
-
If the value of the [[CrossOriginPropertyDescriptorMap]] internal slot of O contains an entry whose key is crossOriginKey, then return that entry’s value.
-
Let originalDesc be OrdinaryGetOwnProperty(O, P).
-
Let crossOriginDesc be CrossOriginPropertyDescriptor(e, originalDesc).
-
Create an entry in the value of the [[CrossOriginPropertyDescriptorMap]] internal slot of O with key crossOriginKey and value crossOriginDesc.
-
Return crossOriginDesc.
-
-
-
Return undefined.
6.2.3.3.1. CrossOriginPropertyDescriptor ( crossOriginProperty, originalDesc )
-
If crossOriginProperty.[[NeedsGet]] and crossOriginProperty.[[NeedsSet]] are absent, then:
-
Let value be originalDesc.[[Value]].
-
If IsCallable(value) is true, set value to CrossOriginFunctionWrapper(true, value).
-
Return PropertyDescriptor{ [[Value]]: value, [[Enumerable]]: false, [[Writable]]: false, [[Configurable]]: true }.
-
-
Otherwise:
-
Let crossOriginGet be CrossOriginFunctionWrapper(crossOriginProperty.[[NeedsGet]], originalDesc.[[Get]]).
-
Let crossOriginSet be CrossOriginFunctionWrapper(crossOriginProperty.[[NeedsSet]], originalDesc.[[Set]]).
-
Return PropertyDescriptor{ [[Get]]: crossOriginGet, [[Set]]: crossOriginSet, [[Enumerable]]: false, [[Configurable]]: true }.
-
6.2.3.3.2. CrossOriginFunctionWrapper ( needsWrapping, functionToWrap )
-
If needsWrapping is false, then return undefined.
-
Return a new cross-origin wrapper function whose [[Wrapped]] internal slot is functionToWrap.
A cross-origin wrapper function is an anonymous built-in function that has a [[Wrapped]] internal slot.
When a cross-origin wrapper function F is called with a list of arguments argumentsList, the following steps are taken:
-
Assert: F has a [[Wrapped]] internal slot that is a function.
-
Let wrappedFunction be the [[Wrapped]] internal slot of F.
-
Return Call(wrappedFunction, this, argumentsList).
Due to this being invoked from a different origin, a cross-origin wrapper function will have a different value for Function.prototype
from the function being wrapped. This follows from how JavaScript
creates anonymous built-in functions.
6.2.3.4. CrossOriginGet ( O, P, Receiver )
-
Let desc be O.[[GetOwnProperty]](P).
-
Assert: desc is not undefined.
-
If IsDataDescriptor(desc) is true, then return desc.[[Value]].
-
Assert: IsAccessorDescriptor(desc) is true.
-
Let getter be desc.[[Get]].
-
If getter is undefined, throw a "
SecurityError
"DOMException
. -
Return Call(getter, Receiver).
6.2.3.5. CrossOriginSet ( O, P, V, Receiver )
-
Let desc be O.[[GetOwnProperty]](P).
-
Assert: desc is not undefined.
-
If IsAccessorDescriptor(desc) is true, then:
-
Let setter be desc.[[Set]].
-
If setter is undefined, return false.
-
Perform Call(setter, Receiver, «V»).
-
Return true.
-
-
Return false.
6.2.3.6. CrossOriginOwnPropertyKeys ( O )
-
Let keys be a new empty List.
-
Repeat for each e that is an element of CrossOriginProperties(O):
-
Add e.[[Property]] as the last element of keys.
-
-
Return keys.
6.3. The Window
object
[PrimaryGlobal, LegacyUnenumerableNamedProperties] /*sealed*/ interface Window : EventTarget { // the current browsing context [Unforgeable] readonly attribute WindowProxy window; [Replaceable] readonly attribute WindowProxy self; [Unforgeable] readonly attribute Document document; attribute DOMString name; [PutForwards=href, Unforgeable] readonly attribute Location location; readonly attribute History history; [Replaceable] readonly attribute BarProp locationbar; [Replaceable] readonly attribute BarProp menubar; [Replaceable] readonly attribute BarProp personalbar; [Replaceable] readonly attribute BarProp scrollbars; [Replaceable] readonly attribute BarProp statusbar; [Replaceable] readonly attribute BarProp toolbar; attribute DOMString status; void close(); readonly attribute boolean closed; void stop(); void focus(); void blur(); // other browsing contexts [Replaceable] readonly attribute WindowProxy frames; [Replaceable] readonly attribute unsigned long length; [Unforgeable] readonly attribute WindowProxy top; attribute any opener; [Replaceable] readonly attribute WindowProxy parent; readonly attribute Element? frameElement; WindowProxy open(optional DOMString url = "about:blank", optional DOMString target = "_blank", [TreatNullAs=EmptyString] optional DOMString features = "", optional boolean replace = false); getter WindowProxy (unsigned long index); getter object (DOMString name); // the user agent readonly attribute Navigator navigator; // user prompts void alert(); void alert(DOMString message); boolean confirm(optional DOMString message = ""); DOMString? prompt(optional DOMString message = "", optional DOMString default = ""); void print(); any showModalDialog(DOMString url, optional any argument); // deprecated unsigned long requestAnimationFrame(FrameRequestCallback callback); void cancelAnimationFrame(unsigned long handle); }; Window implements GlobalEventHandlers; Window implements WindowEventHandlers; callback FrameRequestCallback = void (DOMHighResTimeStamp time);
- window .
window
- window .
frames
- window .
self
- window .
-
These attributes all return window.
- window .
document
-
Returns the
Document
associated with window. - document .
defaultView
-
Returns the
Window
object of the active document.
The window
, frames
, and self
IDL attributes must all return the Window
object’s browsing context’s WindowProxy
object.
The document
IDL attribute must return the Window
object’s newest Document
object.
The Document
object associated with a Window
object can change in
exactly one case: when the navigate algorithm initializes a new Document
object for the
first page loaded in a browsing context. In that specific case, the Window
object of
the original about:blank page is reused and gets a new Document
object.
The defaultView
IDL attribute of the Document
interface must return the Document
's browsing context’s WindowProxy
object, if
there is one, or null otherwise.
For historical reasons, Window
objects must also have a writable, configurable,
non-enumerable property named HTMLDocument
whose value is the Document
interface object.
6.3.1. APIs for creating and navigating browsing contexts by name
- window = window .
open
( [ url [, target [, features [, replace ] ] ] ] ) -
Opens a window to show url (defaults to
about:blank
), and returns it. The target argument gives the name of the new window. If a window exists with that name already, it is reused. The replace attribute, if true, means that whatever page is currently open in that window will be removed from the window’s session history. The features argument can be used to influence the rendering of the new window. - window .
name
[ = value ] -
Returns the name of the window.
Can be set, to change the name.
- window .
close
() -
Closes the window.
- window .
closed
-
Returns true if the window has been closed, false otherwise.
- window .
stop
() -
Cancels the document load.
The open()
method on Window
objects
provides a mechanism for navigating an existing browsing
context or opening and navigating an auxiliary browsing context.
When the method is invoked, the user agent must run the following steps:
- Let entry settings be the entry settings object when the method was invoked.
- Let url be the first argument.
- Let target be the second argument.
- Let features be the third argument.
- Let replace be the fourth argument.
- Let source browsing context be the responsible browsing context specified by entry settings.
- If target is the empty string, let it be the string "
_blank
" instead. -
If the user has indicated a preference for which browsing context to navigate, follow these substeps:
- Let target browsing context be the browsing context indicated by the user.
- If target browsing context is a new top-level browsing context, let the source browsing context be set as target browsing context’s one permitted sandboxed navigator.
For example, suppose there is a user agent that supports control-clicking a link to open it in a new tab. If a user clicks in that user agent on an element whose
onclick
handler uses thewindow.open()
API to open a page in an iframe, but, while doing so, holds the control key down, the user agent could override the selection of the target browsing context to instead target a new tab.Otherwise, apply the rules for choosing a browsing context given a browsing context name using target as the name and source browsing context as the context in which the algorithm is executed. If this results in there not being a chosen browsing context, then throw an
InvalidAccessError
exception and abort these steps. Otherwise, let target browsing context be the browsing context so obtained. - If target browsing context was just created, either as part of the rules for choosing a browsing context given a browsing context name or due to the user indicating a preference for navigating a new top-level browsing context, then let new be true. Otherwise, let it be false.
- Interpret features as defined in the CSSOM View specification. [CSSOM-VIEW]
-
If url is the empty string, run the appropriate steps from the following list:
- If new is false
- Jump to the step labeled end.
- If new is true
- Let resource be the URL "
about:blank
".
Otherwise, parse url relative to entry settings, and let resource be the resulting URL record, if any. If the parse a URL algorithm failed, then run one of the following two steps instead:
- Let resource be a resource representing an inline error page.
- If new is false, jump to the step labeled end, otherwise, let resource be the URL "
about:blank
".
-
If resource is "
about:blank
" and new is true, queue a task to fire a simple event namedload
at target browsing context’sWindow
object, with target override set to target browsing context’sWindow
object’sDocument
object.Otherwise, navigate target browsing context to resource, with the exceptions enabled flag set. If new is true, then replacement must be enabled also. The source browsing context is source browsing context.
- End: Return the
WindowProxy
object of target browsing context.
The name
attribute of the Window
object
must, on getting, return the current name of the browsing context, if one is set, or the empty string otherwise; and, on setting, set
the name of the browsing context to the
new value.
The name gets reset when the browsing context is navigated to another domain.
The close()
method on Window
objects should, if all the following conditions are met, close the browsing context A:
- The corresponding browsing context A is script-closable.
- The responsible browsing context specified by the incumbent settings object is familiar with the browsing context A.
- The responsible browsing context specified by the incumbent settings object is allowed to navigate the browsing context A.
A browsing context is script-closable if it is an auxiliary
browsing context that was created by a script (as opposed to by an action of the user), or
if it is a top-level browsing context whose session history contains
only one Document
.
The closed
attribute on Window
objects must return true if the Window
object’s browsing context has
been discarded, and false otherwise.
The stop()
method on Window
objects should, if there is an existing attempt to navigate the browsing
context and that attempt is not currently running the unload a document algorithm, cancel that navigation; then, it must abort the active document of the browsing
context of the Window
object on which it was invoked.
6.3.2. Accessing other browsing contexts
- window .
length
- Returns the number of child browsing contexts.
- window[index]
- Returns the indicated child browsing context.
The number of child browsing contexts of a Window
object W is the number
of child browsing contexts that are nested through elements that are in a Document
that is the active document of the Window
object’s associated Document
object’s browsing context.
The length
IDL attribute’s getter must return the number of child browsing contexts of this Window
object.
Indexed access to child browsing contexts is defined through the [[GetOwnProperty]] internal method of the WindowProxy
object.
6.3.3. Named access on the Window
object
- window[name]
-
Returns the indicated element or collection of elements.
As a general rule, relying on this will lead to brittle code. Which IDs end up mapping to this API can vary over time, as new features are added to the Web platform, for example. Instead of this, use
document.getElementById()
ordocument.querySelector()
.
The child browsing context name property set consists of the browsing context names of any child browsing context of the active document whose name is not the empty string, with duplicates omitted.
The Window
interface supports named properties.
The supported property names at any moment consist of the following, in tree order,
ignoring later duplicates:
-
the value of the
name
content attribute for alla
,applet
,area
,embed
,form
,frameset
,img
, andobject
elements in the active document that have a non-emptyname
content attribute, and -
the value of the
id
content attribute of any HTML element in the active document with a non-emptyid
content attribute.
To determine the value of a named property name when the Window
object is indexed for property retrieval, the user agent must
return the value obtained using the following steps:
-
Let objects be the list of named objects with the name name in the active document.
There will be at least one such object, by definition.
-
If objects contains a nested browsing context, then return the
WindowProxy
object of the nested browsing context corresponding to the first browsing context container in tree order whose browsing context is in objects, and abort these steps. -
Otherwise, if objects has only one element, return that element and abort these steps.
-
Otherwise return an
HTMLCollection
rooted at theDocument
node, whose filter matches only named objects with the name name. (By definition, these will all be elements.)
Named objects with the name name, for the purposes of the above algorithm, are those that are either:
- child browsing contexts of the active document whose name is name,
a
,applet
,area
,embed
,form
,frameset
,img
, orobject
elements that have aname
content attribute whose value is name, or- html elements that have an
id
content attribute whose value is name.
6.3.4. Garbage collection and browsing contexts
A browsing context has a strong reference to each of its Document
s
and its WindowProxy
object, and the user agent itself has a strong reference to its top-level browsing contexts.
A Document
has a strong reference to its Window
object.
A Window
object has a strong reference to its Document
object through its document
attribute. Thus, references from other scripts to either of
those objects will keep both alive. Similarly, both Document
and Window
objects have implied strong references to the WindowProxy
object.
Each script has a strong reference to its settings object, and each environment settings object has strong references to its global object, responsible browsing context, and responsible document (if any).
When a browsing context is to discard a Document
, the user
agent must run the following steps:
- Set the
Document
's salvageable state to false. - Run any unloading document cleanup steps for the
Document
that are defined by this specification and other applicable specifications. - Abort the
Document
. - Remove any tasks associated with the
Document
in any task source, without running those tasks. - Discard all the child browsing contexts of the
Document
. - Lose the strong reference from the
Document
's browsing context to theDocument
.
Whenever a Document
object is discarded, it is also removed from the list of the worker’s Documents
of each worker whose list contains that Document
.
When a browsing context is discarded, the strong reference from the user
agent itself to the browsing context must be severed, and all the Document
objects for all the entries in the browsing context’s session
history must be discarded as well.
User agents may discard top-level browsing contexts at any time (typically, in
response to user requests, e.g., when a user force-closes a window containing one or more top-level browsing contexts). Other browsing contexts must be discarded once their WindowProxy
object is eligible for garbage collection.
6.3.5. Closing browsing contexts
When the user agent is required to close a browsing context, it must run the following steps:
- Let specified browsing context be the browsing context being closed.
- Prompt to unload the active document of the specified browsing context. If the user refused to allow the document to be unloaded, then abort these steps.
- Unload the active document of the specified browsing context with the recycle parameter set to false.
- Remove the specified browsing context from the user interface (e.g., close or hide its tab in a tabbed browser).
- Discard the specified browsing context.
User agents should offer users the ability to arbitrarily close any top-level browsing context.
6.3.6. Browser interface elements
To allow Web pages to integrate with Web browsers, certain Web browser interface elements are exposed in a limited way to scripts in Web pages.
Each interface element is represented by a BarProp
object:
interface BarProp { readonly attribute boolean visible; };
- window .
locationbar
.visible
- Returns true if the location bar is visible; otherwise, returns false.
- window .
menubar
.visible
- Returns true if the menu bar is visible; otherwise, returns false.
- window .
personalbar
.visible
- Returns true if the personal bar is visible; otherwise, returns false.
- window .
scrollbars
.visible
- Returns true if the scroll bars are visible; otherwise, returns false.
- window .
statusbar
.visible
- Returns true if the status bar is visible; otherwise, returns false.
- window .
toolbar
.visible
- Returns true if the toolbar is visible; otherwise, returns false.
The visible attribute, on getting, must return either true or a value determined by the user agent to most accurately represent the visibility state of the user interface element that the object represents, as described below.
The following BarProp
objects exist for each Document
object in a browsing context. Some of the user interface elements represented by these objects
might have no equivalent in some user agents; for those user agents, except when otherwise
specified, the object must act as if it was present and visible (i.e., its visible
attribute must return true).
- The location bar
BarProp
object - Represents the user interface element that contains a control that displays the URL of the active document, or some similar interface concept.
- The menu bar
BarProp
object - Represents the user interface element that contains a list of commands in menu form, or some similar interface concept.
- The personal bar
BarProp
object - Represents the user interface element that contains links to the user’s favorite pages, or some similar interface concept.
- The scrollbar
BarProp
object - Represents the user interface element that contains a scrolling mechanism, or some similar interface concept.
- The status bar
BarProp
object - Represents a user interface element found immediately below or after the document, as
appropriate for the user’s media, which typically provides information about ongoing network
activity or information about elements that the user’s pointing device is current indicating. If
the user agent has no such user interface element, then the object may act as if the
corresponding user interface element was absent (i.e., its
visible
attribute may return false). - The toolbar
BarProp
object - Represents the user interface element found immediately above or before the document, as
appropriate for the user’s media, which typically provides session history traversal
controls (back and forward buttons, reload buttons, etc). If the user agent has no such user
interface element, then the object may act as if the corresponding user interface element was
absent (i.e., its
visible
attribute may return false).
The locationbar
attribute must return the location bar BarProp
object.
The menubar
attribute must return the
menu bar BarProp
object.
The personalbar
attribute must return the personal bar BarProp
object.
The scrollbars
attribute must return the scrollbar BarProp
object.
The statusbar
attribute must return the status bar BarProp
object.
The toolbar
attribute must return the
toolbar BarProp
object.
For historical reasons, the status
attribute
on the Window
object must, on getting, return the last string it was set to, and on
setting, must set itself to the new value. When the Window
object is created, the
attribute must be set to the empty string. It does not do anything else.
6.3.7. The WindowProxy
object
A WindowProxy
is an exotic object that wraps a Window
ordinary object, indirecting most operations through to the wrapped object. Each browsing context has an associated WindowProxy
object. When the browsing context is navigated, the Window
object wrapped by the browsing context’s associated WindowProxy
object is changed.
There is no WindowProxy
interface object.
Every WindowProxy
object has a [[Window]] internal slot
representing the wrapped Window
object.
Although WindowProxy
is named as a "proxy", it does not do polymorphic
dispatch on its target’s internal methods as a real proxy would, due to a desire to reuse
machinery between WindowProxy
and Location
objects. As long as the Window
object
remains an ordinary object this is unobservable and can be implemented either way.
WindowProxy
object
returned by the window
accessor on the global object. All of the
expressions following the assignment return true, because the WindowProxy
object passes
most operations through to the underlying ordinary Window
object.
var x = window; x instanceof Window; // true x === this; // true
6.3.7.1. The WindowProxy
internal methods
The WindowProxy
object internal methods are described in the subsections below.
6.3.7.1.1. [[GetPrototypeOf]] ( )
-
Let W be the value of the [[Window]] internal slot of this.
-
If IsPlatformObjectSameOrigin(W) is true, then return ! OrdinaryGetPrototypeOf(W).
-
Return null.
6.3.7.1.2. [[SetPrototypeOf]] ( V )
-
Return false.
6.3.7.1.3. [[IsExtensible]] ( )
-
Return true.
6.3.7.1.4. [[PreventExtensions]] ( )
-
Return false.
6.3.7.1.5. [[GetOwnProperty]] ( P )
-
Let W be the value of the [[Window]] internal slot of this.
-
If P is an array index property name, then:
-
Let index be ToUint32(P).
-
Let maxProperties be the number of child browsing contexts of W.
-
Let value be undefined.
-
If maxProperties is greater than 0 and index is less than maxProperties, then:
-
Set value to the
WindowProxy
object of the indexth child browsing context of theDocument
that is nested through an element that is in W’sDocument
, sorted in the order that the elements nesting those browsing contexts were most recently inserted into theDocument
, theWindowProxy
object of the most recently inserted browsing context container’s nested browsing context being last.
-
-
Return PropertyDescriptor{ [[Value]]: value, [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.
-
-
If IsPlatformObjectSameOrigin(W) is true, then return OrdinaryGetOwnProperty(W, P).
This violates JavaScript’s internal method invariants.
-
Let property be CrossOriginGetOwnPropertyHelper(W, P).
-
If property is not undefined, return property.
-
If property is undefined and P is in the child browsing context name property set, then:
-
Let value be the
WindowProxy
object of the named object with the name P. -
Return PropertyDescriptor{ [[Value]]: value, [[Enumerable]]: false, [[Writable]]: false, [[Configurable]]: true }.
-
-
Throw a "
SecurityError
"DOMException
.
6.3.7.1.6. [[DefineOwnProperty]] ( P, Desc )
-
If P is an array index property name, return false.
-
Let W be the value of the [[Window]] internal slot of this.
-
If IsPlatformObjectSameOrigin(W) is true, then return OrdinaryDefineOwnProperty(W, P, Desc).
See above about how this violates JavaScript’s internal method invariants.
-
Return false.
6.3.7.1.7. [[Get]] ( P, Receiver )
-
Let W be the value of the [[Window]] internal slot of this.
-
If IsPlatformObjectSameOrigin(W) is true, then return OrdinaryGet(this, P, Receiver).
-
Return ? CrossOriginGet(this, P, Receiver).
6.3.7.1.8. [[Set]] ( P, V, Receiver )
-
Let W be the value of the [[Window]] internal slot of this.
-
If IsPlatformObjectSameOrigin(W) is true, then return OrdinarySet(W, this, Receiver).
-
Return CrossOriginSet(this, P, V, Receiver).
6.3.7.1.9. [[Delete]] ( P )
-
If P is an array index property name, return false.
-
Let W be the value of the [[Window]] internal slot of this.
-
If IsPlatformObjectSameOrigin(W) is true, then return OrdinaryDelete(W, P).
-
Return false.
6.3.7.1.10. [[OwnPropertyKeys]] ( )
-
Let W be the value of the [[Window]] internal slot of this.
-
Let keys be a new empty List.
-
Let maxProperties be the number of child browsing contexts of W.
-
Let index be 0.
-
Repeat while index < maxProperties,
-
Add ! ToString(index) as the last element of keys.
-
Increment index by 1.
-
-
If IsPlatformObjectSameOrigin(W) is true, then return the concatenation of keys and ! OrdinaryOwnPropertyKeys(W).
-
Return the concatenation of keys and ! CrossOriginOwnPropertyKeys(W).
6.4. Origin
Origins are the fundamental currency of the Web’s security model. Two actors in the Web platform that share an origin are assumed to trust each other and to have the same authority. Actors with differing origins are considered potentially hostile versus each other, and are isolated from each other to varying degrees.
For example, if Example Bank’s Web site, hosted at bank.example.com
, tries to examine the DOM of Example Charity’s Web site, hosted at charity.example.org
, a "SecurityError
" DOMException
will be raised.
An origin is one of the following:
-
An opaque origin
-
An internal value, with no serialisation, for which the only meaningful operation is testing for equality.
-
A tuple origin
-
A tuple consists of:
Origins can be shared, e.g., among multiple Document
objects. Furthermore, origins are generally immutable. Only the domain of a tuple origin can be changed, and only through the document.domain
API.
The effective domain of an origin origin is computed as follows:
-
If origin is an opaque origin, then return origin.
-
If origin’s domain is non-null, then return origin’s domain.
-
Return origin’s host.
Various specification objects are defined to have an origin. These origins are determined as follows:
-
For
Document
objects -
- If the
Document
's active sandboxing flag set has its sandboxed origin browsing context flag set - A unique opaque origin is assigned when the
Document
is created. - If the
Document
's URL’s scheme is a network scheme -
A copy of the
Document
's URL’s origin assigned when theDocument
is created.The
document.open()
method can change theDocument
's URL to "about:blank
". Therefore the origin is assigned when theDocument
is created. - If the
Document
is the initial "about:blank
" document - The one it was assigned when its browsing context was created.
- If the
Document
is a non-initial "about:blank
" document- If the
Document
was generated from adata:
URL found in anotherDocument
or in a script - If the
- The origin of the incumbent settings object when the navigate algorithm was invoked, or, if no script was involved, of the node document of the element that initiated the navigation to that URL.
- If the
Document
was created as part of the processing forjavascript:
URLs - The origin of the active document of the browsing context being navigated when the navigate algorithm was invoked.
- If the
Document
is aniframe
srcdoc
document - The origin of the
Document
's browsing context’s browsing context container’s node document. - If the
Document
was obtained in some other manner (e.g., adata:
URL typed in by the user or that was returned as the location of a redirect, aDocument
created using thecreateDocument()
API, etc) -
The default behavior as defined in the DOM standard applies. [DOM].
The origin is a unique opaque origin assigned when the
Document
is created.
- If the
-
For images of
img
elements -
- If the image data is CORS-cross-origin
- A unique opaque origin assigned when the image is created.
- If the image data is CORS-same-origin
- The
img
element’s node document’s origin.
-
- If the media data is CORS-cross-origin
- A unique opaque origin assigned when the media data is fetched.
- If the media data is CORS-same-origin
- The media element’s node document’s origin.
-
For fonts
-
For a downloadable Web font it is a copy of the origin of the URL record used to obtain the font (after any redirects). [CSS-FONTS-3] [CSS-FONT-LOADING-3]
For a locally installed system font it is the origin of the
Document
in which that font is being used.
Other specifications can override the above definitions by themselves specifying the origin of
a particular Document
object, image, media element, or font.
The Unicode serialization of an origin is the string obtained by applying the following algorithm to the given origin origin:
-
If origin is an opaque origin, then return "
null
". -
Let host be origin’s host.
-
Let unicodeHost be host if host is not a domain, and the result of applying domain to Unicode to host otherwise.
-
Let unicodeOrigin be a new tuple origin consisting origin’s scheme, unicodeHost, and origin’s port.
-
Return the ASCII serialization of an origin, given unicodeOrigin.
The name ASCII serialization of an origin is misleading, as it merely serialises an origin, which are all ASCII by default due to the URL parser.
https
", "xn--maraa-rta.example
",
null, null) is "https://maraña.example
". The ASCII serialization of an origin is the string obtained by applying the following algorithm to the given origin origin:
-
If origin is an opaque origin, then return "
null
". -
Otherwise, let result be origin’s scheme.
-
Append "
://
" to result. -
Append origin’s host, serialized, to result.
-
If origin’s port is non-null, append a U+003A COLON character (:), and origin’s port, serialized, to result.
-
Return result.
Two origins A and B are said to be same origin if the following algorithm returns true:
-
If A and B are the same opaque origin, then return true.
-
If A and B are both tuple origins, and their schemes, hosts, and ports are identical, then return true.
-
Return false.
Two origins A and B are said to be same origin-domain if the following algorithm returns true:
-
If A and B are the same opaque origin, then return true.
-
If A and B are both tuple origins, run these substeps:
-
If A and B’s schemes are identical, and their domains are identical and non-null, then return true.
-
Otherwise, if A and B are same origin and their domains are identical and null, then return true.
-
-
Return false.
A | B | same origin | same origin-domain |
---|---|---|---|
("https ", "example.org ", null, null)
| ("https ", "example.org ", null, null)
| ✅ | ✅ |
("https ", "example.org ", 314, "example.org ")
| ("https ", "example.org ", 420, "example.org ")
| ❌ | ✅ |
("https ", "example.org ", null, null)
| ("https ", "example.org ", null, "example.org ")
| ✅ | ❌ |
("https ", "example.org ", null, "example.org ")
| ("http", "example.org ", null, "example.org ")
| ❌ | ❌ |
6.4.1. Relaxing the same-origin restriction
- document .
domain
[ = domain ] -
Returns the current domain used for security checks.
Can be set to a value that removes subdomains, to change the origin’s domain to allow pages on other subdomains of the same domain (if they do the same thing) to access each other. (Can’t be set in sandboxed
iframe
s.)
The domain
attribute’s getter must run these
steps:
-
If this
Document
object does not have a browsing context, then return the empty string. -
Let effectiveDomain be this
Document
's origin’s effective domain. -
If effectiveDomain is an opaque origin, then return the empty string.
-
Return effectiveDomain, serialised.
The domain
attribute on setting must run these steps:
-
If this
Document
object has no browsing context, throw a "SecurityError
"DOMException
. -
If this
Document
object’s active sandboxing flag set has its sandboxeddocument.domain
browsing context flag set, then throw a "SecurityError
"DOMException
. -
If the given value is the empty string, then throw a "
SecurityError
"DOMException
. -
Let host be the result of parsing the given value.
-
If host is failure, then throw a "
SecurityError
"DOMException
. -
Let effectiveDomain be this
Document
object’s origin’s effective domain. -
If host is not equal to effectiveDomain, then run these substeps:
-
If host or effectiveDomain is not domain, then throw a "
SecurityError
"DOMException
.This is meant to exclude hosts that are an IPv4 address or an IPv6 address.
-
If host, prefixed by a U+002E FULL STOP (.), does not exactly match the effectiveDomain, then throw a "
SecurityError
"DOMException
. -
If host matches a suffix in the Public Suffix List, or, if host, prefixed by a U+002E FULL STOP (.), matches the end of a suffix in the Public Suffix List, then throw a "
SecurityError
"DOMException
. [PSL]Suffixes must be compared after applying the host parser algorithm. [URL]
-
-
Set origin’s domain to host.
The document.domain
attribute is used to enable pages on
different hosts of a domain to access each others' DOMs.
Do not use the document.domain
attribute when using shared
hosting. If an untrusted third party is able to host an HTTP server at the same IP address but on
a different port, then the same-origin protection that normally protects two different sites on
the same host will fail, as the ports are ignored when comparing origins after the document.domain
attribute has been used.
6.5. Sandboxing
A sandboxing flag set is a set of zero or more of the following flags, which are used to restrict the abilities that potentially untrusted resources have:
- The sandboxed navigation browsing context flag
-
This flag prevents content from navigating browsing contexts other than the sandboxed browsing context itself (or browsing contexts further nested inside it), auxiliary browsing contexts (which are protected by the sandboxed auxiliary navigation browsing context flag defined next), and the top-level browsing context (which is protected by the sandboxed top-level navigation browsing context flag defined below).
If the sandboxed auxiliary navigation browsing context flag is not set, then in certain cases the restrictions nonetheless allow popups (new top-level browsing contexts) to be opened. These browsing contexts always have one permitted sandboxed navigator, set when the browsing context is created, which allows the browsing context that created them to actually navigate them. (Otherwise, the sandboxed navigation browsing context flag would prevent them from being navigated even if they were opened.)
- The sandboxed auxiliary navigation browsing context flag
-
This flag prevents content from creating new auxiliary browsing contexts, e.g., using the
target
attribute, thewindow.open()
method, or theshowModalDialog()
method. - The sandboxed top-level navigation browsing context flag
-
This flag prevents content from navigating their top-level browsing context and prevents content from closing their top-level browsing context.
When the sandboxed top-level navigation browsing context flag is not set, content can navigate its top-level browsing context, but other browsing contexts are still protected by the sandboxed navigation browsing context flag and possibly the sandboxed auxiliary navigation browsing context flag.
- The sandboxed plugins browsing context flag
-
This flag prevents content from instantiating plugins, whether using the
embed
element, theobject
element, theapplet
element, or through navigation of a nested browsing context, unless those plugins can be secured. - The sandboxed origin browsing context flag
-
This flag forces content into a unique origin, thus preventing it from accessing other content from the same origin.
This flag also prevents script from reading from or writing to the
document.cookie
IDL attribute, and blocks access tolocalStorage
. [WEBSTORAGE] - The sandboxed forms browsing context flag
-
This flag blocks form submission.
- The sandboxed pointer lock browsing context flag
-
This flag disables the Pointer Lock API. [POINTERLOCK]
- The sandboxed scripts browsing context flag
-
This flag blocks script execution.
- The sandboxed automatic features browsing context flag
-
This flag blocks features that trigger automatically, such as automatically playing a video or automatically focusing a form control.
- The sandboxed storage area URLs flag
-
This flag prevents URL schemes that use storage areas from being able to access the origin’s data.
- The sandboxed fullscreen browsing context flag
-
This flag prevents content from using the
requestFullscreen()
method. - The sandboxed
document.domain
browsing context flag - This flag prevents content from using the
document.domain
setter. - The sandbox propagates to auxiliary browsing contexts flag
-
This flag prevents content from escaping the sandbox by ensuring that any auxiliary browsing context it creates inherits the content’s active sandboxing flag set.
- The sandboxed modals flag
-
This flag prevents content from using any of the following features to produce modal dialogs:
window.alert()
window.confirm()
window.print()
window.prompt()
window.showModalDialog()
- the
beforeunload
event
When the user agent is to parse a sandboxing directive, given a string input, a sandboxing flag set output, and optionally an allow fullscreen flag, it must run the following steps:
- Split input on spaces, to obtain tokens.
- Let output be empty.
-
Add the following flags to output:
- The sandboxed navigation browsing context flag.
- The sandboxed auxiliary navigation browsing context flag, unless tokens contains the
allow-popups
keyword. - The sandboxed top-level navigation browsing context flag, unless tokens contains the
allow-top-navigation
keyword. - The sandboxed plugins browsing context flag.
-
The sandboxed origin browsing context flag, unless the tokens contains the
allow-same-origin
keyword.The
allow-same-origin
keyword is intended for two cases.First, it can be used to allow content from the same site to be sandboxed to disable scripting, while still allowing access to the DOM of the sandboxed content.
Second, it can be used to embed content from a third-party site, sandboxed to prevent that site from opening pop-up windows, etc, without preventing the embedded page from communicating back to its originating site, using the database APIs to store data, etc.
- The sandboxed forms browsing context flag, unless tokens contains the
allow-forms
keyword. - The sandboxed pointer lock browsing context flag, unless tokens contains the
allow-pointer-lock
keyword. - The sandboxed scripts browsing context flag, unless tokens contains the
allow-scripts
keyword. -
The sandboxed automatic features browsing context flag, unless tokens contains the
allow-scripts
keyword (defined above).This flag is relaxed by the same keyword as scripts, because when scripts are enabled these features are trivially possible anyway, and it would be unfortunate to force authors to use script to do them when sandboxed rather than allowing them to use the declarative features.
- The sandboxed storage area URLs flag.
- The sandboxed fullscreen browsing context flag, unless the allow fullscreen flag was passed to the parse a sandboxing directive flag.
- The sandboxed
document.domain
browsing context flag. - The sandbox propagates to auxiliary browsing contexts flag, unless tokens contains the
allow-popups-to-escape-sandbox
keyword. - The sandboxed modals flag, unless tokens contains the
allow-modals
keyword.
Every top-level browsing context has a popup sandboxing flag set, which is a sandboxing flag set. When a browsing context is created, its popup sandboxing flag set must be empty. It is populated by the rules for choosing a browsing context given a browsing context name.
Every nested browsing context has an iframe
sandboxing flag
set, which is a sandboxing flag set. Which flags in a nested browsing context’s iframe
sandboxing flag set are set at any
particular time is determined by the iframe
element’s sandbox
attribute.
Every Document
has an active sandboxing flag set, which is a sandboxing flag set. When the Document
is created, its active
sandboxing flag set must be empty. It is populated by the navigation
algorithm.
Every resource that is obtained by the navigation algorithm has a forced sandboxing flag set, which is a sandboxing flag set. A resource by default has no flags set in its forced sandboxing flag set, but other specifications can define that certain flags are set.
In particular, the forced sandboxing flag set is used by the Content Security Policy specification. [CSP3]
When a user agent is to implement the sandboxing for a Document
, it
must populate Document
's active sandboxing flag set with the union of
the flags that are present in the following sandboxing flag
sets at the time the Document
object is created:
- If the
Document
's browsing context is a top-level browsing context, then: the flags set on the browsing context’s popup sandboxing flag set. - If the
Document
's browsing context is a nested browsing context, then: the flags set on the browsing context’siframe
sandboxing flag set. - If the
Document
's browsing context is a nested browsing context, then: the flags set on the browsing context’s parent browsing context’s active document’s active sandboxing flag set. - The flags set on the
Document
's resource’s forced sandboxing flag set, if it has one.
6.6. Session history and navigation
6.6.1. The session history of browsing contexts
The sequence of Document
s in a browsing context is its session
history. Each browsing context, including nested browsing contexts, has a distinct session history. A browsing
context’s session history consists of a flat list of session history entries. Each session history entry consists, at a
minimum, of a URL, and each entry may in addition have a state object, a
title, a Document
object, form data, a scroll restoration mode, a scroll
position, and other information associated with it.
Each entry, when first created, has a Document
. However, when a Document
is not active, it’s possible for it to be discarded to free resources. The URL and
other data in a session history entry is then used to bring a new Document
into being to take the place of the original, should the user agent find
itself having to reactivate that Document
.
Titles associated with session history
entries need not have any relation with the current title
of the Document
. The title of a session history entry is intended to explain
the state of the document at that point, so that the user can navigate the document’s history.
URLs without associated state objects are added to the session history as the user (or script) navigates from page to page.
Each Document
object in a browsing context’s session
history is associated with a unique History
object which must all model the
same underlying session history.
history
attribute of the Window
interface must return
the object implementing the History
interface for that Window
object’s newest Document
. A state object is an object representing a user interface state.
Pages can add state objects to the session history. These are then returned to the script when the user (or script) goes back in the history, thus enabling authors to use the "navigation" metaphor even in one-page applications.
Document
instance and it would have to be
reconstructed if a new Document
were opened.
An example of the latter would be something like keeping track of the precise coordinate from
which a pop-up div
was made to animate, so that if the user goes back, it can be
made to animate to the same location. Or alternatively, it could be used to keep a pointer into a
cache of data that would be fetched from the server based on the information in the URL, so that when going back and forward, the information doesn’t have to be fetched
again.
At any point, one of the entries in the session history is the current entry. This is the entry representing the active document of the browsing context. Which entry is the current entry is changed by the algorithms defined in this specification, e.g., during session history traversal.
The current entry is usually an entry for the address of the Document
. However, it can also be one of the entries for state objects added
to the history by that document.
An entry with persisted user state is one that also has user-agent defined state. This specification does not specify what kind of state can be stored.
For example, some user agents might want to persist the scroll position, or the values of form controls.
User agents that persist the value of form controls are encouraged to also persist
their directionality (the value of the element’s dir
attribute).
This prevents values from being displayed incorrectly after a history traversal when the user had
originally entered the values with an explicit, non-default directionality.
An entry’s scroll restoration mode indicates whether the user agent should restore the persisted scroll position (if any) when traversing to it. The scroll restoration mode may be one of the following:
- "
auto
" - The user agent is responsible for restoring the scroll position upon navigation.
- "
manual
" - The page is responsible for restoring the scroll position and the user agent does not attempt to do so automatically
If unspecified, the scroll restoration mode of a new entry must be set to
"auto
".
Entries that consist of state objects share the same Document
as the entry for the page that was active when they were added.
Contiguous entries that differ just by fragment identifier also share the same Document
.
All entries that share the same Document
(and that are therefore
merely different states of one particular document) are contiguous by definition.
Each Document
in a browsing context can also have a latest
entry. This is the entry for that Document
to which the browsing
context’s session history was most recently traversed. When a Document
is created, it initially has no latest entry.
User agents may discard the Document
objects of entries other than the current entry that are not referenced from any
script, reloading the pages afresh when the user or script navigates back to such pages. This
specification does not specify when user agents should discard Document
objects and
when they should cache them.
Entries that have had their Document
objects discarded must, for the purposes of
the algorithms given below, act as if they had not. When the user or script navigates back or
forwards to a page which has no in-memory DOM objects, any other entries that shared the same Document
object with it must share the new object as well.
6.6.2. The History
interface
enum ScrollRestoration { "auto", "manual" };
interface History { readonly attribute unsigned long length; attribute ScrollRestoration scrollRestoration; readonly attribute any state; void go(optional long delta = 0); void back(); void forward(); void pushState(any data, DOMString title, optional DOMString? url = null); void replaceState(any data, DOMString title, optional DOMString? url = null); };
- window .
history
.length
-
Returns the number of entries in the joint session history.
- window .
history
.scrollRestoration
[ = value ] -
Returns the scroll restoration mode of the current entry in the session history.
Can be set, to change the scroll restoration mode of the current entry in the session history.
- window .
history
.state
-
Returns the current state object.
- window .
history
.go
( [ delta ] ) -
Goes back or forward the specified number of steps in the joint session history.
A zero delta will reload the current page.
If the delta is out of range, does nothing.
- window .
history
.back
() -
Goes back one step in the joint session history.
If there is no previous page, does nothing.
- window .
history
.forward
() -
Goes forward one step in the joint session history.
If there is no next page, does nothing.
- window .
history
.pushState
(data, title [, url ] ) -
Pushes the given data onto the session history, with the given title, and, if provided and not null, the given URL.
- window .
history
.replaceState
(data, title [, url ] ) -
Updates the current entry in the session history to have the given data, title, and, if provided and not null, URL.
The joint session history of a top-level browsing context is the union
of all the session histories of all browsing contexts of all the fully active Document
objects that share that top-level browsing context, with all the entries that are current entries in their respective session histories removed except for the current entry of the joint session
history.
The current entry of the joint session history is the entry that most recently became a current entry in its session history.
Entries in the joint session history are ordered chronologically by the time they were added to their respective session histories. Each entry has an index; the earliest entry has index 0, and the subsequent entries are numbered with consecutively increasing integers (1, 2, 3, etc).
Since each Document
in a browsing context might have a
different event loop, the actual state of the joint session history can
be somewhat nebulous. For example, two sibling iframe
elements could both traverse from one unique origin to another at the same time,
so their precise order might not be well-defined; similarly, since they might only find out about
each other later, they might disagree about the length of the joint session
history.
The length
attribute of the History
interface, on getting, must return the number of entries in the top-level browsing context’s joint session history. If this History
object is associated with a Document
that is not fully active, getting must instead throw a "SecurityError
" DOMException
.
The actual entries are not accessible from script.
The scrollRestoration
attribute
of the History interface, on getting, must return the scroll restoration mode of the
current entry in the session history. On setting, the scroll restoration mode of the current entry in the session history must be set to the new
value. If this History
object is associated with a Document
that is
not fully active, both getting and setting must instead throw a
"SecurityError
" DOMException
.
The state
attribute of the History
interface, on getting, must return the last value it was set to by the user
agent. If this History
object is associated with a Document
that is
not fully active, getting must instead throw a SecurityError
DOMException
.
Initially, its value must be null.
When the go(delta)
method is
invoked, if delta is zero, the user agent must act as if the location.reload()
method was called instead. Otherwise,
the user agent must traverse the history by a delta whose value is delta If this History
object is associated with a Document
that is not fully active, invoking must instead throw a
"SecurityError
" DOMException
.
When the back()
method is invoked, the user
agent must traverse the history by a delta −1. If this History
object is associated with a Document
that is not fully active,
invoking must instead throw a "SecurityError
" DOMException
.
When the forward()
method is invoked, the
user agent must traverse the history by a delta +1. If this History
object is associated with a Document
that is not fully active,
invoking must instead throw a "SecurityError
" DOMException
.
Each top-level browsing context has a session history traversal queue, initially empty, to which tasks can be added.
Each top-level browsing context, when created, must begin running the following algorithm, known as the session history event loop for that top-level browsing context, in parallel:
- Wait until this top-level browsing context’s session history traversal queue is not empty.
- Pull the first task from this top-level browsing context’s session history traversal queue, and execute it.
- Return to the first step of this algorithm.
The session history event loop helps coordinate cross-browsing-context transitions of the joint session history: since each browsing context might, at any particular time, have a different event loop (this can happen if the user agent has more than one event loop per unit of related browsing contexts), transitions would otherwise have to involve cross-event-loop synchronization.
To traverse the history by a delta delta, the user agent must append a task to this top-level browsing context’s session history traversal queue, the task consisting of running the following steps:
- If the index of the current entry of the joint session history plus delta is less than zero or greater than or equal to the number of items in the joint session history, then abort these steps.
- Let specified entry be the entry in the joint session history whose index is the sum of delta and the index of the current entry of the joint session history.
- Let specified browsing context be the browsing context of the specified entry.
- If the specified browsing context’s active document’s unload a document algorithm is currently running, abort these steps.
-
Queue a task that consists of running the following substeps. The relevant event loop is that of the specified browsing context’s active document. The task source for the queued task is the history traversal task source.
- If there is an ongoing attempt to navigate specified browsing context that has not yet matured (i.e., it has not passed the
point of making its
Document
the active document), then cancel that attempt to navigate the browsing context. -
If the specified browsing context’s active document is not the same
Document
as theDocument
of the specified entry, then run these substeps:- Prompt to unload the active document of the specified browsing context. If the user refused to allow the document to be unloaded, then abort these steps.
- Unload the active document of the specified browsing context with the recycle parameter set to false.
- Traverse the history of the specified browsing context to the specified entry.
- If there is an ongoing attempt to navigate specified browsing context that has not yet matured (i.e., it has not passed the
point of making its
When the user navigates through a browsing context, e.g., using a browser’s back and forward buttons, the user agent must traverse the history by a delta equivalent to the action specified by the user.
The pushState()
method adds a state object entry to
the history.
The replaceState()
method updates the state object,
title, and optionally the URL of the current entry in the history.
When either of these methods is invoked, the user agent must run the following steps:
-
If this
History
object is associated with aDocument
that is not fully active, throw a "SecurityError
"DOMException
. -
Optionally, abort these steps. (For example, the user agent might disallow calls to these methods that are invoked on a timer, or from event listeners that are not triggered in response to a clear user action, or that are invoked in rapid succession.)
-
Let targetRealm be this
History
object’s relevant settings object’s Realm. -
Let cloned data be a StructuredClone(data, targetRealm). Rethrow any exceptions.
-
If the third argument is not null, run these substeps:
-
Parse the value of the third argument, relative to the entry settings object.
-
If that fails, throw a "
SecurityError
"DOMException
and abort these steps. -
Let new URL be the resulting URL record.
-
Compare new URL to the document’s URL. If any component of these two URL records differ other than the path, query, and fragment components, then throw a "
SecurityError
"DOMException
and abort these steps. -
If the origin of new URL is not the same as the origin of the responsible document specified by the entry settings object, and either the path or query components of the two URL records compared in the previous step differ, throw a "
SecurityError
"DOMException
and abort these steps. (This prevents sandboxed content from spoofing other pages on the same origin.)
-
-
If the third argument is null, then let new URL be the URL of the current entry.
-
If the method invoked was the
pushState()
method:-
Remove all the entries in the browsing context’s session history after the current entry. If the current entry is the last entry in the session history, then no entries are removed.
This doesn’t necessarily have to affect the user agent’s user interface.
-
Remove any tasks queued by the history traversal task source that are associated with any
Document
objects in the top-level browsing context’s document family. -
If appropriate, update the current entry to reflect any state that the user agent wishes to persist. The entry is then said to be an entry with persisted user state.
-
Add a state object entry to the session history, after the current entry, with cloned data as the state object, the given title as the title, new URL as the URL of the entry, and the scroll restoration mode of the current entry in the session history as the scroll restoration mode.
-
Update the current entry to be this newly added entry.
Otherwise, if the method invoked was the
replaceState()
method:-
Update the current entry in the session history so that cloned data is the entry’s new state object, the given title is the new title, and new URL is the entry’s new URL.
-
-
If the current entry in the session history represents a non-GET request (e.g., it was the result of a POST submission) then update it to instead represent a GET request.
-
Set the document’s URL to new URL.
Since this is neither a navigation of the browsing context nor a history traversal, it does not cause a
hashchange
event to be fired. -
Let targetRealm be this
History
object’s relevant settings object’s Realm. -
Set
history.state
to StructuredClone(cloned data, targetRealm). -
Let the latest entry of the
Document
of the current entry be the current entry.
The title is purely advisory. User agents might use the title in the user interface.
User agents may limit the number of state objects added to the session history per page. If a
page hits the user agent-defined limit, user agents must remove the entry immediately after the
first entry for that Document
object in the session history after having added the new
entry. (Thus the state history acts as a FIFO buffer for eviction, but as a LIFO buffer for
navigation.)
A static page implementing the x=5 position in such a game could look like the following:
<!DOCTYPE HTML> <!-- this is https://example.com/line?x=5 --> <title>Line Game - 5</title> <p>You are at coordinate 5 on the line.</p> <p> <a href="?x=6">Advance to 6</a> or <a href="?x=4">retreat to 4</a>? </p>
The problem with such a system is that each time the user clicks, the whole page has to be reloaded. Here instead is another way of doing it, using script:
<!DOCTYPE HTML> <!-- this starts off as https://example.com/line?x=5 --> <title>Line Game - 5</title> <p>You are at coordinate <span>5</span> on the line.</p> <p> <a href="?x=6" onclick="go(1); return false;">Advance to 6</a> or <a href="?x=4" onclick="go(-1); return false;">retreat to 4</a>? </p> <script> var currentPage = 5; // prefilled by server function go(d) { setupPage(currentPage + d); history.pushState(currentPage, document.title, '?x=' + currentPage); } onpopstate = function(event) { setupPage(event.state); } function setupPage(page) { currentPage = page; document.title = 'Line Game - ' + currentPage; document.getElementById('coord').textContent = currentPage; document.links[0].href = '?x=' + (currentPage+1); document.links[0].textContent = 'Advance to ' + (currentPage+1); document.links[1].href = '?x=' + (currentPage-1); document.links[1].textContent = 'retreat to ' + (currentPage-1); } </script>
In systems without script, this still works like the previous example. However, users that do have script support can now navigate much faster, since there is no network access for the same experience. Furthermore, contrary to the experience the user would have with just a naïve script-based approach, bookmarking and navigating the session history still work.
In the example above, the data argument to the pushState()
method is the same information as would be sent
to the server, but in a more convenient form, so that the script doesn’t have to parse the URL
each time the user navigates.
title
element at that time. For example, here is a simple
page that shows a block in the title
element. Clearly, when navigating backwards to
a previous state the user does not go back in time, and therefore it would be inappropriate to
put the time in the session history title.
<!DOCTYPE HTML> <TITLE>Line</TITLE> <SCRIPT> setInterval(function () { document.title = 'Line - ' + new Date(); }, 1000); var i = 1; function inc() { set(i+1); history.pushState(i, 'Line - ' + i); } function set(newI) { i = newI; document.forms.F.I.value = newI; } </SCRIPT> <BODY ONPOPSTATE="set(event.state)"> <FORM NAME=F> State: <OUTPUT NAME=I>1</OUTPUT> <INPUT VALUE="Increment" TYPE=BUTTON ONCLICK="inc()"> </FORM>
scrollRestoration
attribute as soon as possible
(e.g., in the first script
element in the document’s head
element) to
ensure that any entry added to the history session gets the desired scroll restoration mode.
<head> <script> if ('scrollRestoration' in history) history.scrollRestoration = 'manual'; </script> </head>
6.6.3. Implementation notes for session history
This section is non-normative.
The History
interface is not meant to place restrictions on how implementations represent the
session history to the user.
For example, session history could be implemented in a tree-like manner, with each page having
multiple "forward" pages. This specification doesn’t define how the linear list of pages in the history
object are derived from the actual session history as seen from the user’s
perspective.
Similarly, a page containing two iframe
s has a history
object distinct from the iframe
s' history
objects, despite the fact that typical Web browsers present the
user with just one "Back" button, with a session history that interleaves the navigation of the
two inner frames and the outer page.
Security: It is suggested that to avoid letting a page "hijack" the history navigation
facilities of a UA by abusing pushState()
, the UA provide the user with a way to jump
back to the previous page (rather than just going back to the previous state). For example, the
back button could have a drop down showing just the pages in the session history, and not showing
any of the states. Similarly, an aural browser could have two "back" commands, one that goes back
to the previous state, and one that jumps straight back to the previous page.
For both pushState()
and replaceState()
, user agents are encouraged to
prevent abuse of these APIs via too-frequent calls or over-large state objects. As detailed above,
the algorithm explicitly allows user agents to ignore any such calls when appropriate.
6.6.4. The Location
interface
Each Window
object is associated with a unique instance of a Location
object, allocated
when the Window
object is created.
To create a Location
object, run these steps:
-
Let location be a new
Location
platform object. -
Perform ! location.[[DefineOwnProperty]]("
toString
", { [[Value]]: %ObjProto_toString%, [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }). -
Perform ! location.[[DefineOwnProperty]]("
toJSON
", { [[Value]]: undefined, [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }). -
Perform ! location.[[DefineOwnProperty]]("
valueOf
", { [[Value]]: %ObjProto_valueOf%, [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }). -
Perform ! location.[[DefineOwnProperty]](@@toPrimitive, { [[Value]]: undefined, [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }).
-
Set the value of the [[DefaultProperties]] internal slot of location to location.[[OwnPropertyKeys]]().
-
Return location.
- document .
location
[ = value ]- window .
location
[ = value ] - window .
-
Returns a
Location
object with the current page’s location.Can be set, to navigate to another page.
The location
attribute of the Document
interface must return the Location
object for that Document
object’s global object,
if it has a browsing context, and null otherwise.
The location
attribute of the Window
interface
must return the Location
object for that Window
object.
Location
objects provide a representation of the URL of the active document of their Document
's browsing context, and allow the current entry of the browsing context’s session history to be changed, by adding or
replacing entries in the history
object.
[Unforgeable] interface Location { stringifier attribute USVString href; readonly attribute USVString origin; attribute USVString protocol; attribute USVString host; attribute USVString hostname; attribute USVString port; attribute USVString pathname; attribute USVString search; attribute USVString hash; void assign(USVString url); void replace(USVString url); void reload(); [SameObject] readonly attribute USVString[] ancestorOrigins; };
- location .
toString()
- location .
href
- location .
-
Returns the
Location
object’s URL.Can be set, to navigate to the given URL.
- location .
origin
- Returns the
Location
object’s URL’s origin. - location .
protocol
-
Returns the
Location
object’s URL’s scheme.Can be set, to navigate to the same URL with a changed scheme.
- location .
host
-
Returns the
Location
object’s URL’s host and port (if different from the default port for the scheme).Can be set, to navigate to the same URL with a changed host and port.
- location .
hostname
-
Returns the
Location
object’s URL’s host.Can be set, to navigate to the same URL with a changed host.
- location .
port
-
Returns the
Location
object’s URL’s port.Can be set, to navigate to the same URL with a changed port.
- location .
pathname
-
Returns the
Location
object’s URL’s path.Can be set, to navigate to the same URL with a changed path.
- location .
search
-
Returns the
Location
object’s URL’s query (includes leading "?
" if non-empty).Can be set, to navigate to the same URL with a changed query (ignores leading "
?
"). - location .
hash
-
Returns the
Location
object’s URL’s fragment (includes leading "#
" if non-empty).Can be set, to navigate to the same URL with a changed fragment (ignores leading "
#
"). - location .
assign
(url) - Navigates to the given URL.
- location .
replace
(url) - Removes the current page from the session history and navigates to the given URL.
- location .
reload()
- Reloads the current page.
- location .
ancestorOrigins
- Returns an array whose values are the origins of the ancestor browsing contexts, from the parent browsing context to the top-level browsing context.
A Location
object has an associated relevant Document
, which is this Location
object’s associated Document
object’s browsing context’s active document.
A Location
object has an associated url, which is this Location
object’s relevant Document
’s URL.
A Location
object has an associated ancestor origins array. When a Location
object is created, its ancestor origins array must be set to a array created from the list
of strings that the following steps would produce:
-
Let output be an empty ordered list of strings.
-
Let current be the browsing context of the
Document
with which theLocation
object is associated. -
Loop: If current has no parent browsing context, jump to the step labeled End.
-
Let current be current’s parent browsing context.
-
Append the Unicode serialization of current’s active document’s origin to output as a new value.
-
Return to the step labeled Loop.
-
End: Return output.
A Location
object has an associated Location
-object-setter navigate algorithm, which given a url, runs these steps:
-
If any of the following conditions are met, let replacement flag be unset; otherwise, let it be set:
-
This
Location
object’s relevantDocument
has completely loaded, or -
In the task in which the algorithm is running, an activation behavior is currently being processed whose
click
event was trusted, or -
In the task in which the algorithm is running, the event listener for a trusted
click
event is being handled.
-
-
Location
-object navigate, given url and replacement flag.
To Location
-object navigate, given a url and replacement flag, run these steps:
-
The source browsing context is the responsible browsing context specified by the incumbent settings object.
-
Navigate the browsing context to url, with the exceptions enabled flag set. Rethrow any exceptions.
If the replacement flag is set or the browsing context’s session history contains only one
Document
, and that was theabout:blank
Document
created when the browsing context was created, then the navigation must be done with replacement enabled.
The href
attribute’s getter must return this Location
object’s URL, serialized.
The href
attribute’s setter must run these steps:
- Let newURL be the resulting URL string of parsing the given value relative to the entry settings object’s API base URL.
- If that aborted with an error, throw a
TypeError
exception. Location
-object-setter navigate to newURL.
The origin
attribute’s getter must return
the Unicode serialization of this Location
object’s URL’s origin.
It returns the Unicode rather than the ASCII serialization for
compatibility with MessageEvent
.
The protocol
attribute’s getter must
return this Location
object’s URL’s scheme, followed by ":
".
The protocol
attribute’s setter must run these
steps:
- Let copyURL be a copy of this
Location
object’s URL. - Let possibleFailure be the result of basic URL parsing the given value, followed by "
:
", with copyURL as url and scheme start state as state override. - If possibleFailure is failure, throw a
TypeError
exception. - If copyURL’s scheme is not "
http
" or "https
", terminate these steps. Location
-object-setter navigate to copyURL.
The host
attribute’s getter must run these
steps:
- Let url be this
Location
object’s URL. - If url’s host is null, return the empty string.
- If url’s port is null, return url’s host, serialized.
- Return url’s host, serialized, followed by "
:
" and url’s port, serialized.
The host
attribute’s setter must run these steps:
- Let copyURL be a copy of this
Location
object’s URL. - If copyURL’s non-relative flag is set, terminate these steps.
- Basic URL parse the given value, with copyURL as url and host state as state override.
Location
-object-setter navigate to copyURL.
The hostname
attribute’s getter must
run these steps:
- If this
Location
object’s URL’s host is null, return the empty string. - Return this
Location
object’s URL’s host, serialized.
The hostname
attribute’s setter must run these
steps:
- Let copyURL be a copy of this
Location
object’s URL. - If copyURL’s non-relative flag is set, terminate these steps.
- Basic URL parse the given value, with copyURL as url and hostname state as state override.
Location
-object-setter navigate to copyURL.
The port
attribute’s getter must run these
steps:
- If this
Location
object’s URL’s port is null, return the empty string. - Return this
Location
object’s URL’s port, serialized.
The port
attribute’s setter must run these steps:
- Let copyURL be a copy of this
Location
object’s URL. - If copyURL’s host is null, copyURL’s non-relative flag is set, or copyURL’s scheme is "
file
", terminate these steps. - Basic URL parse the given value, with copyURL as url and port state as state override.
Location
-object-setter navigate to copyURL.
The pathname
attribute’s getter must
run these steps:
- Let url be this
Location
object’s URL. - If url’s non-relative flag is set, return the first string in url’s path.
- Return "
/
", followed by the strings in url’s path (including empty strings), separated from each other by "/
".
The pathname
attribute’s setter must run these
steps:
- Let copyURL be a copy of this
Location
object’s URL. - If copyURL’s non-relative flag is set, terminate these steps.
- Set copyURL’s path to the empty list.
- Basic URL parse the given value, with copyURL as url and path start state as state override.
Location
-object-setter navigate to copyURL.
The search
attribute’s getter must run
these steps:
- If this
Location
object’s URL’s query is either null or the empty string, return the empty string. - Return "
?
", followed by thisLocation
object’s URL’s query.
The search
attribute’s setter must run these
steps:
- Let copyURL be a copy of this
Location
object’s URL. - If the given value is the empty string, set copyURL’s query to null.
-
Otherwise, run these substeps:
- Let input be the given value with a single leading "
?
" removed, if any. - Set copyURL’s query to the empty string.
- Basic URL parse input, with copyURL as url and query state as state override,
and the relevant
Document
’s document’s character encoding as encoding override.
- Let input be the given value with a single leading "
Location
-object-setter navigate to copyURL.
The hash
attribute’s getter must run these
steps:
- If this
Location
object’s URL’s fragment is either null or the empty string, return the empty string. - Return "
#
", followed by thisLocation
object’s URL’s fragment.
The hash
attribute’s setter must run these steps:
- Let copyURL be a copy of this
Location
object’s URL. - If copyURL’s scheme is "
javascript
", terminate these steps. - If the given value is the empty string, set copyURL’s fragment to null.
-
Otherwise, run these substeps:
- Let input be the given value with a single leading "
#
" removed, if any. - Set copyURL’s fragment to the empty string.
- Basic URL parse input, with copyURL as url and fragment state as state override.
- Let input be the given value with a single leading "
Location
-object-setter navigate to copyURL.
When the assign(url)
method is invoked, the user agent must run the following steps:
-
Parse url, relative to the API base URL specified by the entry settings object and let parsedURL be the resulting URL string.
If this is not successful, throw a "
SyntaxError
"DOMException
and abort these steps. Location
-object navigate to parsedURL.
When the replace(url)
method is invoked, the user agent must run the following steps:
-
Parse url, relative to the API base URL specified by the entry settings object and let parsedURL be the resulting URL string.
If this is not successful, throw a "
SyntaxError
"DOMException
and abort these steps. Location
-object navigate to parsedURL with the replacement flag set.
When the reload()
method is invoked, the
user agent must run the appropriate steps from the following list:
- If the currently executing task is the dispatch of a
resize
event in response to the user resizing the browsing context - Repaint the browsing context and abort these steps.
- If the browsing context’s active document is an
iframe
srcdoc
document - Reprocess the
iframe
attributes of the browsing context’s browsing context container. - If the browsing context’s active document has its reload override flag set
- Perform an overridden reload, with the browsing context being navigated as the responsible browsing context.
- Otherwise
- Navigate the browsing context to the document’s URL with the exceptions enabled flag set and replacement enabled. The source browsing context must be the browsing context being navigated. This is a reload-triggered navigation. Rethrow any exceptions.
When a user requests that the active document of a browsing context be reloaded through a user interface element, the user agent should navigate the browsing context to the same resource as that Document
, with replacement enabled. In the case of non-idempotent
methods (e.g., HTTP POST), the user agent should prompt the user to confirm the operation first,
since otherwise transactions (e.g., purchases or database modifications) could be repeated. User
agents may allow the user to explicitly override any caches when reloading. If browsing
context’s active document’s reload override flag is set, then the
user agent may instead perform an overridden reload rather than the navigation
described in this paragraph (with the browsing context being reloaded as the source browsing context).
The ancestorOrigins
attribute’s getter must run
these steps:
-
If this
Location
object’s relevantDocument
’s origin is not same origin-domain with the entry settings object’s origin, then throw a "SecurityError
"DOMException
. -
Otherwise, return this
Location
object’s ancestor origins array.
The Location
object requires additional logic beyond IDL for security purposes. The internal
slot and internal methods Location
objects must implement are defined below.
Every Location
object has a [[DefaultProperties]] internal slot representing its
own properties at time of its creation.
6.7. Browsing the Web
6.7.1. Navigating across documents
Certain actions cause the browsing context to navigate to a new resource. A user agent may provide various ways for the user to explicitly cause a browsing context to navigate, in addition to those defined in this specification.
For example, following a hyperlink, §4.10.22 Form submission, and the window.open()
and location.assign()
methods can all cause a browsing context to
navigate.
A resource has a URL, but that might not be the only information necessary
to identify it. For example, a form submission that uses HTTP POST would also have the HTTP method
and payload. Similarly, an iframe
srcdoc
document needs to know the data it is to use.
Navigation always involves source browsing context, which is the browsing context which was responsible for starting the navigation.
When a browsing context is navigated to a new resource, the user agent must run the following steps:
-
If the source browsing context is not allowed to navigate the browsing context being navigated, then abort these steps.
If these steps are aborted here, the user agent may instead offer to open the new resource in a new top-level browsing context or in the top-level browsing context of the source browsing context, at the user’s option, in which case the user agent must navigate that designated top-level browsing context to the new resource as if the user had requested it independently.
Doing so, however, can be dangerous, as it means that the user is overriding the author’s explicit request to sandbox the content.
If the navigate algorithm was invoked optionally with an exceptions enabled flag, and it is aborted on this step, then in addition to aborting this algorithm, the user agent must also throw a "
SecurityError
"DOMException
. - If there is a preexisting attempt to navigate the browsing context, and the source browsing context is the same as the browsing context being navigated, and that attempt is currently running the unload a document algorithm, and the origin of the URL of the resource being loaded in that navigation is not the same origin as the origin of the URL of the resource being loaded in this navigation, then abort these steps without affecting the preexisting attempt to navigate the browsing context.
- If a task queued by the traverse the history by a delta algorithm is running the unload a document algorithm for the active document of the browsing context being navigated, then abort these steps without affecting the unload a document algorithm or the aforementioned history traversal task.
- If the prompt to unload a document algorithm is being run for the active document of the browsing context being navigated, then abort these steps without affecting the prompt to unload a document algorithm.
-
Let gone async be false.
The handle redirects step later in this algorithm can in certain cases jump back to the step labeled fragment identifiers. Since, between those two steps, this algorithm goes from operating immediately in the context of the calling task to operating in parallel independent of the event loop, some of the intervening steps need to be able to handle both being run as part of a task and running in parallel. The gone async flag is thus used to make these steps aware of which mode they are operating in.
- Fragment identifiers: If this is not a reload-triggered navigation: apply the URL parser algorithm to the absolute URL of the new resource and the address of the active document of the browsing context being navigated; if all the components of the resulting parsed
URLs, ignoring any fragment components, are
identical, and the new resource is to be fetched using
GET
, and the URL record of the new resource has a fragment component that is not null (even if it is empty), then navigate to that fragment identifier and abort these steps. - If gone async is false, cancel any preexisting but not yet mature attempt to navigate the browsing
context, including canceling any instances of the fetch algorithm started by those attempts. If one of those attempts
has already created and initialized a new
Document
object, abort thatDocument
also. (Navigation attempts that have matured already have session history entries, and are therefore handled during the update the session history with the new page algorithm, later.) - If the new resource is to be handled using a mechanism that does not affect the browsing context, e.g., ignoring the navigation request altogether because the specified scheme is not one of the supported protocols, then abort these steps and proceed with that mechanism instead.
-
If gone async is false, prompt to unload the
Document
object. If the user refused to allow the document to be unloaded, then abort these steps.If this instance of the navigation algorithm gets canceled while this step is running, the prompt to unload a document algorithm must nonetheless be run to completion.
- If gone async is false, abort the active document of the browsing context.
-
If the new resource is to be handled by displaying some sort of inline content, e.g., an error message because the specified scheme is not one of the supported protocols, or an inline prompt to allow the user to select a registered handler for the given scheme, then display the inline content and abort these steps.
In the case of a registered handler being used, the algorithm will be reinvoked with a new URL to handle the request.
-
If the browsing context being navigated is a nested browsing context, then put it in the delaying
load
events mode.The user agent must take this nested browsing context out of the delaying
load
events mode when this navigation algorithm later matures, or when it terminates (whether due to having run all the steps, or being canceled, or being aborted), whichever happens first. -
This is the step that attempts to obtain the resource, if necessary. Jump to the first appropriate substep:
- If the resource has already been obtained (e.g., because it is being used to populate an
object
element’s new child browsing context) - Skip this step. The data is already available.
- If the new resource is a URL whose scheme is
javascript
-
Queue a task to run these "
javascript:
URL" steps, associated with the active document of the browsing context being navigated:-
If the origin of the source browsing context is not the same origin as the origin of the active document of the browsing context being navigated, then let result be undefined, and jump to the step labeled process results below.
-
Let urlRecord be the result of running the URL parser on the URL of the new resource.
-
Let script source be the empty string.
-
Append the first string of urlRecord’s path component to script source.
-
If urlRecord’s query component is not null, then first append a U+003F QUESTION MARK character (?) to script source, and then append urlRecord’s query component to script source.
-
If urlRecord’s fragment component is not null, then first append a U+0023 NUMBER SIGN character (#) to script source, and then append urlRecord’s fragment component to script source.
-
Replace script source with the result of applying the percent decode algorithm to script source.
-
Replace script source with the result of applying the UTF-8 decode algorithm to script source.
-
Let address be the address of the active document of the browsing context being navigated.
-
Let settings be the relevant settings object of the browsing context being navigated.
-
Let script be the result of creating a classic script given script source and settings.
-
Let result be the result of running the classic script script. If evaluation was unsuccessful, let result be undefined instead. (The result will also be undefined if scripting is disabled.)
-
Process results: If Type(result) is not
String
, then the result of obtaining the resource for the URL is a response whose status is204
.Otherwise, the result of obtaining the resource for the URL is a response whose header list consists of
Content-Type
/text/html
and whose body is result, and whose HTTPS state is settings’s HTTPS state.When it comes time to set the document’s address in the navigation algorithm, use address as the override URL.
The task source for this task is the DOM manipulation task source.
So for example ajavascript:
URL in anhref
attribute of ana
element would only be evaluated when the link was followed, while such a URL in thesrc
attribute of aniframe
element would be evaluated in the context of theiframe
’s own nested browsing context when theiframe
is being set up; once evaluated, its return value (if it was not void) would replace that browsing context’sDocument
, thus also changing theWindow
object of that browsing context. -
- Otherwise
-
- Let request be the new resource.
- If request is a URL, set request to a new request whose URL is request.
- Set request’s client to the source browsing context’s active document’s
Window
object’s environment settings object, target browsing context to the browsing context being navigated, destination to "document
", mode to "navigate
", credentials mode to "include
", use-URL-credentials flag, and redirect mode to "manual
". - Set request’s omit-
Origin
-header flag. - If request’s method is not
GET
, or, if the navigation algorithm was invoked as a result of the form submission algorithm, then if there is an origin of the active document of the source browsing context, unset request’s omit-Origin
-header flag. - Otherwise, if the browsing context being navigated is a child
browsing context, and the browsing context container of the browsing context being navigated has a browsing context scope
origin, set request’s origin to that browsing context scope origin and unset request’s omit-
Origin
-header flag. - Fetch request.
- If the resource has already been obtained (e.g., because it is being used to populate an
-
If gone async is false, return to whatever algorithm invoked the navigation steps and continue running these steps in parallel.
- Let gone async be true.
- Wait for one or more bytes to be available or for the user agent to establish that the resource in question is empty. During this time, the user agent may allow the user to cancel this navigation attempt or start other navigation attempts.
-
Handle redirects: If fetching the resource results in a redirect, and either the URL of the target of the redirect has the same origin as the original resource, or the resource is being obtained using the POST method or a safe method (in HTTP terms), return to the step labeled fragment identifiers with the new resource, except that if the URL of the target of the redirect does not have a fragment identifier and the URL of the resource that led to the redirect does, then the fragment identifier of the resource that led to the redirect must be propagated to the URL of the target of the redirect.
So for instance, if the original URL was "
https://example.com/#!sample
" and "https://example.com/
" is found to redirect to "https://example.com/
", the URL of the new resource will be "https://example.com/#!sample
".Otherwise, if fetching the resource results in a redirect but the URL of the target of the redirect does not have the same origin as the original resource and the resource is being obtained using a method that is neither the POST method nor a safe method (in HTTP terms), then abort these steps. The user agent may indicate to the user that the navigation has been aborted for security reasons.
-
Resource handling: If the resource’s out-of-band metadata (e.g., HTTP headers), not counting any type information (such as the Content-Type HTTP header), requires some sort of processing that will not affect the browsing context, then perform that processing and abort these steps.
Such processing might be triggered by, amongst other things, the following:- HTTP status codes (e.g., 204 No Content or 205 Reset Content)
- Network errors (e.g., the network interface being unavailable)
- Cryptographic protocol failures (e.g., an incorrect TLS certificate)
Responses with HTTP
Content-Disposition
headers specifying theattachment
disposition type must be handled as a download.HTTP 401 responses that do not include a challenge recognized by the user agent must be processed as if they had no challenge, e.g., rendering the entity body as if the response had been 200 OK.
User agents may show the entity body of an HTTP 401 response even when the response does include a recognized challenge, with the option to login being included in a non-modal fashion, to enable the information provided by the server to be used by the user before authenticating. Similarly, user agents should allow the user to authenticate (in a non-modal fashion) against authentication challenges included in other responses such as HTTP 200 OK responses, effectively allowing resources to present HTTP login forms without requiring their use.
- Let type be the computed type of the resource.
-
If the user agent has been configured to process resources of the given type using some mechanism other than rendering the content in a browsing
context, then skip this step. Otherwise, if the type is one of the
following types, jump to the appropriate entry in the following list, and process the resource as
described there:
- an HTML MIME type
- Follow the steps given in the HTML document section, and then, once they have completed, abort this navigate algorithm.
- an XML MIME type that is not an explicitly supported XML type
- Follow the steps given in the XML document section. If that section determines that the content is not to be displayed as a generic XML document, then proceed to the next step in this overall set of steps. Otherwise, once the steps given in the XML document section have completed, abort this navigate algorithm.
- a JavaScript MIME type
- a JSON MIME type that is not an explicitly supported JSON type
- "
text/css
"- "
text/plain
"- "
text/vtt
" - a JSON MIME type that is not an explicitly supported JSON type
- Follow the steps given in the plain text file section, and then, once they have completed, abort this navigate algorithm.
- "
multipart/x-mixed-replace
" - Follow the steps given in the §12.2 multipart/x-mixed-replace section, and then, once they have completed, abort this navigate algorithm.
- A supported image, video, or audio type
- Follow the steps given in the media section, and then, once they have completed, abort this navigate algorithm.
- A type that will use an external application to render the content in the browsing context
- Follow the steps given in the plugin section, and then, once they have completed, abort this navigate algorithm.
An explicitly supported XML type is one for which the user agent is configured to use an external application to render the content (either a plugin rendering directly in the browsing context, or a separate application), or one for which the user agent has dedicated processing rules (e.g., a Web browser with a built-in Atom feed viewer would be said to explicitly support the
application/atom+xml
MIME type).The term JSON MIME type is used to refer to the MIME types
application/json
,text/json
, and any MIME type whose subtype ends with the five characters "+json
".An explicitly supported JSON type is one for which the user agent is configured to use an external application to render the content (either a plugin rendering directly in the browsing context, or a separate application), or one for which the user agent has dedicated processing rules.
Setting the document’s address: If there is no override URL, then any
Document
created by these steps must have its address set to the URL that was originally to be fetched, ignoring any other data that was used to obtain the resource. However, if there is an override URL, then anyDocument
created by these steps must have its address set to that URL instead.An override URL is set when dereferencing a
javascript:
URL and when performing an overridden reload.Initializing a new
Document
object: when aDocument
is created as part of the above steps, the user agent will be required to additionally run the following algorithm after creating the new object:-
If browsingContext’s only entry in its session history is the about:blank
Document
that was added when browsingContext was created, and navigation is occurring with replacement enabled, and thatDocument
has the same origin as the newDocument
, then -
Otherwise,
-
Call the JavaScript InitializeHostDefinedRealm() abstract operation with the following customizations:
-
For the global object, create a new
Window
object window. -
For the global this value, use browsingContext’s
WindowProxy
object. -
Let realm execution context be the created JavaScript execution context.
-
Do not obtain any source texts for scripts.
-
-
Set up a browsing context environment settings object with realm execution context, and let settings object be the result.
-
Set window’s associated
Document
to the newDocument
.
-
-
Set browsingContext’s
WindowProxy
object’s [[Window]] internal slot value to window. -
Set the
Document
's HTTPS state to the HTTPS state of the resource used to generate the document. -
Execute the Initialize a
Document
’s CSP list algorithm on theDocument
object and the resource used to generate the document. [CSP3] -
Set the document’s referrer to the address of the resource from which Request-URIs are obtained as determined when the fetch algorithm obtained the resource, if that algorithm was used and determined such a value; otherwise, set it to the empty string.
-
Implement the sandboxing for the
Document
. -
If the active sandboxing flag set of the
Document
's browsing context or any of its ancestor browsing contexts (if any) have the sandboxed fullscreen browsing context flag set, then skip this step.If the
Document
's browsing context has a browsing context container and either it is not aniframe
element, or it does not have theallowfullscreen
attribute specified, or itsDocument
does not have the fullscreen enabled flag set, then also skip this step.Otherwise, set the
Document
's fullscreen enabled flag. -
Non-document content: If, given type, the new resource is to be handled by displaying some sort of inline content, e.g., a native rendering of the content, an error message because the specified type is not supported, or an inline prompt to allow the user to select a registered handler for the given type, then display the inline content, and then abort these steps.
In the case of a registered handler being used, the algorithm will be reinvoked with a new URL to handle the request.
- Otherwise, the document’s type is such that the resource will not affect the browsing context, e.g., because the resource is to be handed to an external application or because it is an unknown type that will be processed as a download. Process the resource appropriately.
When a resource is handled by passing its URL or data to an external software package separate from the user agent (e.g., handing a mailto:
URL to a mail client, or a Word document to a word
processor), user agents should attempt to mitigate the risk that this is an attempt to exploit the
target software, e.g., by prompting the user to confirm that the source browsing
context’s active document’s origin is to be allowed to invoke the
specified software. In particular, if the navigate algorithm, when it was invoked,
was not allowed to show a popup, the user agent should not invoke the external
software package without prior user confirmation.
For example, there could be a vulnerability in the target software’s URL handler which a hostile page would attempt to exploit by tricking a user into clicking a link.
Some of the sections below, to which the above algorithm defers in certain cases, require the
user agent to update the session history with the new page. When a user agent is
required to do this, it must queue a task (associated with the Document
object of the current entry, not the new one) to run the following steps:
-
Unload the
Document
object of the current entry, with the recycle parameter set to false.If this instance of the navigation algorithm is canceled while this step is running the unload a document algorithm, then the unload a document algorithm must be allowed to run to completion, but this instance of the navigation algorithm must not run beyond this step. (In particular, for instance, the cancelation of this algorithm does not abort any event dispatch or script execution occurring as part of unloading the document or its descendants.)
-
- If the navigation was initiated for entry update of an entry
-
- Replace the
Document
of the entry being updated, and any other entries that referenced the same document as that entry, with the newDocument
. - Traverse the history to the new entry.
This can only happen if the entry being updated is not the current entry, and can never happen with replacement enabled. (It happens when the user tried to traverse to a session history entry that no longer had a
Document
object.) - Replace the
- Otherwise
-
-
Remove all the entries in the browsing context’s session history after the current entry. If the current entry is the last entry in the session history, then no entries are removed.
This doesn’t necessarily have to affect the user agent’s user interface.
- Append a new entry at the end of the
History
object representing the new resource and itsDocument
object, related state, and the default scroll restoration mode of "auto
". - Traverse the history to the new entry. If the navigation was initiated with replacement enabled, then the traversal must itself be initiated with replacement enabled.
-
- The navigation algorithm has now matured.
- Fragment identifier loop: Spin the event loop for a user-agent-defined amount of time, as desired by the user agent implementor. (This is intended to allow the user agent to optimize the user experience in the face of performance concerns.)
- If the
Document
object has no parser, or its parser has stopped parsing, or the user agent has reason to believe the user is no longer interested in scrolling to the fragment identifier, then abort these steps. - Scroll to the fragment identifier given in the document’s address. If this fails to find an indicated part of the document, then return to the fragment identifier loop step.
The task source for this task is the networking task source.
6.7.2. Page load processing model for HTML files
When an HTML document is to be loaded in a browsing context, the user agent must queue a task to create a Document
object, mark it as being an HTML document, set its content type to "text/html
",
initialize the Document
object, and finally create an HTML
parser and associate it with the Document
. Each task that the networking task source places on the task queue while fetching runs must then fill the parser’s input byte
stream with the fetched bytes and cause the HTML parser to perform the
appropriate processing of the input stream.
The input byte stream converts bytes into characters for use in the tokenizer. This process relies, in part, on character encoding information found in the real Content-Type metadata of the resource; the "computed type" is not used for this purpose.
When no more bytes are available, the user agent must queue a task for the parser
to process the implied EOF character, which eventually causes a load
event to be fired.
After creating the Document
object, but before any script execution, certainly
before the parser stops, the user agent must update the
session history with the new page.
The task source for the two tasks mentioned in this section must be the networking task source.
6.7.3. Page load processing model for XML files
When faced with displaying an XML file inline, user agents must follow the requirements defined
in the XML and Namespaces in XML recommendations, RFC 7303, DOM, and other relevant specifications
to create a Document
object and a corresponding XML parser. [XML] [XML-NAMES] [RFC7303] [DOM]
At the time of writing, the XML specification community had not actually yet specified how XML and the DOM interact.
After the Document
is created, the user agent must initialize the Document
object.
The actual HTTP headers and other metadata, not the headers as mutated or implied by the algorithms given in this specification, are the ones that must be used when determining the character encoding according to the rules given in the above specifications. Once the character encoding is established, the document’s character encoding must be set to that character encoding.
User agents may examine the namespace of the root Element
node of this Document
object to perform namespace-based dispatch to alternative processing tools,
e.g., determining that the content is actually a syndication feed and passing it to a feed handler.
If such processing is to take place, abort the steps in this section, and jump to the next step (labeled non-document content) in the navigate steps above.
Otherwise, then, with the newly created Document
, the user agent must update
the session history with the new page. User agents may do this before the complete document
has been parsed (thus achieving incremental rendering), and must do this before any scripts
are to be executed.
Error messages from the parse process (e.g., XML namespace well-formedness errors) may be
reported inline by mutating the Document
.
6.7.4. Page load processing model for text files
When a plain text document is to be loaded in a browsing context, the user agent
must queue a task to create a Document
object, mark it as being an HTML document, set its content type to the computed MIME type of the
resource (type in the navigate algorithm), initialize the Document
object, create an HTML parser, associate it with the Document
, act as if the tokenizer had emitted a start tag token with the tag name
"pre" followed by a single U+000A LINE FEED (LF) character, and switch the HTML parser’s
tokenizer to the §8.2.4.7 PLAINTEXT state. Each task that
the networking task source places on the task queue while fetching runs
must then fill the parser’s input byte stream with the fetched bytes and cause the HTML parser to perform the appropriate processing of the input stream.
The rules for how to convert the bytes of the plain text document into actual characters, and the rules for actually rendering the text to the user, are defined by the specifications for the computed MIME type of the resource (type in the navigate algorithm).
The document’s character encoding must be set to the character encoding used to decode the document.
When no more bytes are available, the user agent must queue a task for the parser
to process the implied EOF character, which eventually causes a load
event to be fired.
After creating the Document
object, but potentially before the page has finished
parsing, the user agent must update the session history with the new page.
User agents may add content to the head
element of the Document
, e.g.,
to link to a style sheet, provide a script, give the document a title
, etc.
In particular, if the user agent supports the Format=Flowed
feature of RFC3676 then the user agent would need to apply extra styling to cause the text to
wrap correctly and to handle the quoting feature. [RFC3676]
The task source for the two tasks mentioned in this section must be the networking task source.
6.7.5. Page load processing model for multipart/x-mixed-replace
resources
When a resource with the type multipart/x-mixed-replace
is to be loaded in a browsing context, the user agent must parse the resource using the rules for
multipart types. [RFC2046]
For each body part obtained from the resource, the user agent must run a new instance of the navigate algorithm, starting from the resource handling step, using the new
body part as the resource being navigated, with replacement enabled if a previous
body part from the same resource resulted in a Document
object being created and initialized, and otherwise using the same
setup as the navigate attempt that caused this section to be invoked in the first
place.
For the purposes of algorithms processing these body parts as if they were complete stand-alone resources, the user agent must act as if there were no more bytes for those resources whenever the boundary following the body part is reached.
Thus, load
events (and for that matter unload
events) do fire for each body part loaded.
6.7.6. Page load processing model for media
When an image, video, or audio resource is to be loaded in a browsing context, the
user agent should create a Document
object, mark it as being an HTML document, set its content
type to the computed MIME type of the resource (type in the navigate algorithm), initialize the Document
object, append
an html
element to the Document
, append a head
element and
a body
element to the html
element, append an element host element for the media, as described below, to the body
element,
and set the appropriate attribute of the element host element, as described
below, to the address of the image, video, or audio resource.
The element host element to create for the media is the element given in the table below in the second cell of the row whose first cell describes the media. The appropriate attribute to set is the one given by the third cell in that same row.
Type of media | Element for the media | Appropriate attribute |
---|---|---|
Image | img
| src
|
Video | video
| src
|
Audio | audio
| src
|
Then, the user agent must act as if it had stopped parsing.
After creating the Document
object, but potentially before the page has finished
fully loading, the user agent must update the session history with the new page.
User agents may add content to the head
element of the Document
, or
attributes to the element host element, e.g., to link to a style sheet, provide a script, give the document a title
, make the media autoplay, etc.
6.7.7. Page load processing model for content that uses plugins
When a resource that requires an external resource to be rendered is to be loaded in a browsing context, the user agent should create a Document
object, mark
it as being an HTML document and mark it as being a plugin document, set its content
type to the computed MIME type of the resource (type in the navigate algorithm), initialize the Document
object, append
an html
element to the Document
, append a head
element and
a body
element to the html
element, append an embed
to the body
element, and set the src
attribute of the embed
element to the address of the resource.
The term plugin document is used by Content Security Policy as part of the mechanism that ensures iframe
s
can’t be used to evade plugin-types
directives. [CSP3]
Then, the user agent must act as if it had stopped parsing.
After creating the Document
object, but potentially before the page has finished
fully loading, the user agent must update the session history with the new page.
User agents may add content to the head
element of the Document
, or
attributes to the embed
element, e.g., to link to a style sheet,
to give the document a title
, etc.
If the Document
's active sandboxing
flag set has its sandboxed plugins browsing context flag set, the synthesized embed
element will fail to render the content if
the relevant plugin cannot be secured.
6.7.8. Page load processing model for inline content that doesn’t have a DOM
When the user agent is to display a user agent page inline in a browsing context,
the user agent should create a Document
object, mark it as being an HTML document, set its content type to "text/html
",
initialize the Document
object, and then either associate that Document
with a custom rendering that is not rendered using the normal Document
rendering rules, or mutate that Document
until it represents
the content the user agent wants to render.
Once the page has been set up, the user agent must act as if it had stopped parsing.
After creating the Document
object, but potentially before the page has been
completely set up, the user agent must update the session history with the new
page.
6.7.9. Navigating to a fragment identifier
When a user agent is supposed to navigate to a fragment identifier, then the user agent must run the following steps:
-
Remove all the entries in the browsing context’s session history after the current entry. If the current entry is the last entry in the session history, then no entries are removed.
This doesn’t necessarily have to affect the user agent’s user interface.
- Remove any tasks queued by the history traversal
task source that are associated with any
Document
objects in the top-level browsing context’s document family. - Append a new entry at the end of the
History
object representing the new resource and itsDocument
object, related state, and current history scroll restoration preference. Its URL must be set to the address to which the user agent was navigating. The title must be left unset. - Traverse the history to the new entry, with the non-blocking events flag set. This will scroll to the fragment identifier given in what is now the document’s address.
If the scrolling fails because the relevant ID has not yet been parsed, then the original navigation algorithm will take care of the scrolling instead, as the last few steps of its update the session history with the new page algorithm.
When the user agent is required to scroll to the fragment identifier and the indicated part of the document, if any, is being rendered, the user agent must either change the scrolling position of the document using the following algorithm, or perform some other action such that the indicated part of the document is brought to the user’s attention. If there is no indicated part, or if the indicated part is not being rendered, then the user agent must do nothing. The aforementioned algorithm is as follows:
- Let target be the indicated part of the document, as defined below.
- If target is the top of the document, then scroll to the beginning of the document for the
Document
, and abort these steps. [CSSOM-VIEW] - Use the scroll an element into view algorithm to scroll target into view, with the align to top flag set. [CSSOM-VIEW]
- Run the focusing steps for that element, with the
Document
's viewport as the fallback target. - Move the sequential focus navigation starting point to target.
The indicated part of the document is the one that the fragment identifier, if any,
identifies. The semantics of the fragment identifier in terms of mapping it to a specific DOM Node
is defined by the specification that defines the MIME type used by the Document
(for example, the processing of fragment identifiers for XML MIME types is the responsibility of RFC7303). [RFC7303]
For HTML documents (and HTML MIME types), the following processing model must be followed to determine what the indicated part of the document is.
- Apply the URL parser algorithm to the URL, and let fragid be the fragment component of the resulting URL record.
- If fragid is the empty string, then the indicated part of the document is the top of the document; stop the algorithm here.
- Let fragid bytes be the result of percent decoding fragid.
- Let decoded fragid be the result of running UTF-8 decode without BOM or fail on fragid bytes. If decoded fragid is failure, jump to the step labeled no decoded fragid.
- If there is an element in the DOM that has an ID exactly equal to decoded fragid, then the first such element in tree order is the indicated part of the document; stop the algorithm here.
- No decoded fragid: If there is an
a
element in the DOM that has aname
attribute whose value is exactly equal to fragid (not decoded fragid), then the first such element in tree order is the indicated part of the document; stop the algorithm here. - If fragid is an ASCII case-insensitive match for the
string
top
, then the indicated part of the document is the top of the document; stop the algorithm here. - Otherwise, there is no indicated part of the document.
For the purposes of the interaction of HTML with Selectors' :target
pseudo-class, the target element is the indicated part of the document, if that is an element; otherwise there is no target element. [CSS3-SELECTORS]
The task source for the task mentioned in this section must be the DOM manipulation task source.
6.7.10. History traversal
When a user agent is required to traverse the history to a specified entry, optionally with replacement enabled, and optionally with the non-blocking events flag set, the user agent must act as follows.
This algorithm is not just invoked when explicitly going back or forwards in the session history — it is also invoked in other situations, for example when navigating a browsing context, as part of updating the session history with the new page.
-
If there is no longer a
Document
object for the entry in question, navigate the browsing context to the resource for that entry to perform an entry update of that entry, and abort these steps. The "navigate" algorithm reinvokes this "traverse" algorithm to complete the traversal, at which point there is aDocument
object and so this step gets skipped. The navigation must be done using the same source browsing context as was used the first time this entry was created. (This can never happen with replacement enabled.)If the resource was obtained using a non-idempotent action, for example a POST form submission, or if the resource is no longer available, for example because the computer is now offline and the page wasn’t cached, navigating to it again might not be possible. In this case, the navigation will result in a different page than previously; for example, it might be an error message explaining the problem or offering to resubmit the form.
- If the current entry’s title was not set by the
pushState()
orreplaceState()
methods, then set its title to the value returned by thedocument.title
IDL attribute. - If appropriate, update the current entry in the browsing
context’s
Document
object’sHistory
object to reflect any state that the user agent wishes to persist. The entry is then said to be an entry with persisted user state. -
If the specified entry has a different
Document
object than the current entry, then run the following substeps:- Remove any tasks queued by the history traversal
task source that are associated with any
Document
objects in the top-level browsing context’s document family. -
If the origin of the
Document
of the specified entry is not the same as the origin of theDocument
of the current entry, then run the following sub-sub-steps:- The current browsing context name must be stored with all the entries in
the history that are associated with
Document
objects with the same origin as the active document and that are contiguous with the current entry. - If the browsing context is a top-level browsing context, but not an auxiliary browsing context, then the browsing context’s browsing context name must be unset.
- The current browsing context name must be stored with all the entries in
the history that are associated with
- Make the specified entry’s
Document
object the active document of the browsing context. -
If the specified entry has a browsing context name stored with it, then run the following sub-sub-steps:
- Set the browsing context’s browsing context name to the name stored with the specified entry.
- Clear any browsing context names stored
with all entries in the history that are associated with
Document
objects with the same origin as the new active document and that are contiguous with the specified entry.
- If the specified entry’s
Document
has any form controls whose autofill field name is "off
", invoke the reset algorithm of each of those elements. -
If the current document readiness of the specified entry’s
Document
is "complete
", queue a task to run the following sub-sub-steps:- If the
Document
's page showing flag is true, then abort this task (i.e., don’t fire the event below). - Set the
Document
's page showing flag to true. -
Run any session history document visibility change steps for
Document
that are defined by other applicable specifications.This is specifically intended for use by the Page Visibility specification. [PAGE-VISIBILITY]
- Fire a trusted event with the name
pageshow
at theWindow
object of thatDocument
, with target override set to theDocument
object, using thePageTransitionEvent
interface, with thepersisted
attribute initialized to true. This event must not bubble, must not be cancelable, and has no default action.
- If the
- Remove any tasks queued by the history traversal
task source that are associated with any
- Set the document’s address to the URL of the specified entry.
- If the specified entry has a URL whose fragment identifier differs
from that of the current entry’s when compared in a case-sensitive manner, and the two share the same
Document
object, then let hash changed be true, and let old URL be the URL of the current entry and new URL be the URL of the specified entry. Otherwise, let hash changed be false. - If the traversal was initiated with replacement enabled, remove the entry immediately before the specified entry in the session history.
- If the specified entry is not an entry with persisted user state, but its URL has a fragment identifier, scroll to the fragment identifier.
- If the entry is an entry with persisted user state, the user agent may restore persisted user state and update aspects of the document and its rendering.
- Let targetRealm be the current Realm Record.
- If the entry is a state object entry, let state be StructuredClone(that state object, targetRealm) of that state object. Otherwise, let state be null.
- Set
history.state
to state. - Let state changed be true if the
Document
of the specified entry has a latest entry, and that entry is not the specified entry; otherwise let it be false. - Let the latest entry of the
Document
of the specified entry be the specified entry. -
If the non-blocking events flag is not set, then run the following steps immediately. Otherwise, the non-blocking events flag is set; queue a task to run the following substeps instead.
- If state changed is true, fire a trusted event with the name
popstate
at theWindow
object of theDocument
, using thePopStateEvent
interface, with thestate
attribute initialized to the value of state. This event must bubble but not be cancelable and has no default action. - If hash changed is true, then fire a trusted event with the name
hashchange
at the browsing context’sWindow
object, using theHashChangeEvent
interface, with theoldURL
attribute initialized to old URL and thenewURL
attribute initialized to new URL. This event must bubble but not be cancelable and has no default action.
- If state changed is true, fire a trusted event with the name
- The current entry is now the specified entry.
The task source for the tasks mentioned above is the DOM manipulation task source.
6.7.10.1. Persisted user state restoration
When the user agent is to restore persisted user state from a history entry, it must run the following steps immediately:
- If the entry has a scroll restoration mode, let scrollRestoration be that. Otherwise let scrollRestoration be "
auto
" - If scrollRestoration is "
manual
" the user agent should not restore the scroll position for the document, otherwise, it may do so. - Optionally, update other aspects of the document and its rendering, for instance values of form fields, that the user agent had previously recorded.
This can even include updating the dir
attribute
of textarea
elements or input
elements whose type
attribute
is in either the Text state or the Search state, if the persisted state includes the
directionality of user input in such controls.
6.7.10.2. The PopStateEvent
interface
[Constructor(DOMString type, optional PopStateEventInit eventInitDict), Exposed=(Window,Worker)] interface PopStateEvent : Event { readonly attribute any state; };
dictionary PopStateEventInit : EventInit { any state; };
- event .
state
-
Returns a copy of the information that was provided to
pushState()
orreplaceState()
.
The state
attribute must return the
value it was initialized to. When the object is created, this attribute must be initialized to
null. It represents the context information for the event, or null, if the state represented is
the initial state of the Document
.
6.7.10.3. The HashChangeEvent
interface
[Constructor(DOMString type, optional HashChangeEventInit eventInitDict), Exposed=(Window,Worker)] interface HashChangeEvent : Event { readonly attribute DOMString oldURL; readonly attribute DOMString newURL; };
dictionary HashChangeEventInit : EventInit { DOMString oldURL; DOMString newURL; };
- event .
oldURL
-
Returns the URL of the session history entry that was previously current.
- event .
newURL
-
Returns the URL of the session history entry that is now current.
The oldURL
attribute must return the
value it was initialized to. When the object is created, this attribute must be initialized to
null. It represents context information for the event, specifically the URL of the session
history entry that was traversed from.
The newURL
attribute must return the
value it was initialized to. When the object is created, this attribute must be initialized to
null. It represents context information for the event, specifically the URL of the session
history entry that was traversed to.
6.7.10.4. The PageTransitionEvent
interface
[Constructor(DOMString type, optional PageTransitionEventInit eventInitDict), Exposed=(Window,Worker)] interface PageTransitionEvent : Event { readonly attribute boolean persisted; };
dictionary PageTransitionEventInit : EventInit { boolean persisted; };
- event .
persisted
-
For the
pageshow
event, returns false if the page is newly being loaded (and theload
event will fire). Otherwise, returns true.For the
pagehide
event, returns false if the page is going away for the last time. Otherwise, returns true, meaning that (if nothing conspires to make the page unsalvageable) the page might be reused if the user navigates back to this page.Things that can cause the page to be unsalvageable include:
document.open()
- Listening for
beforeunload
events - Listening for
unload
events - Having
iframe
s that are not salvageable - Active
WebSocket
objects - Aborting a
Document
The persisted
attribute must
return the value it was initialized to. When the object is created, this attribute must be
initialized to false. It represents the context information for the event.
6.7.11. Unloading documents
A Document
has a salvageable state, which must initially be
true, a fired unload flag, which must initially be false, and a page showing flag, which must initially be false. The page showing flag is used to ensure that
scripts receive pageshow
and pagehide
events in a consistent manner (e.g., that they never
receive two pagehide
events in a row without an intervening pageshow
, or vice versa).
Event loops have a termination nesting level counter, which must initially be zero.
When a user agent is to prompt to unload a document, it must run the following steps.
- Increase the event loop’s termination nesting level by one.
- Increase the
Document
's ignore-opens-during-unload counter by one. - Let event be a new trusted
BeforeUnloadEvent
event object with the namebeforeunload
, which does not bubble but is cancelable. - Dispatch: Dispatch event at the
Document
'sWindow
object. - Decrease the event loop’s termination nesting level by one.
- If any event listeners were triggered by the earlier dispatch step, then set the
Document
's salvageable state to false. -
If the
Document
's active sandboxing flag set does not have its sandboxed modals flag set, and thereturnValue
attribute of the event object is not the empty string, or if the event was canceled, then the user agent should ask the user to confirm that they wish to unload the document.The prompt shown by the user agent may include the string of the
returnValue
attribute, or some leading subset thereof. (A user agent may want to truncate the string to 1024 characters for display, for instance.)The user agent must pause while waiting for the user’s response.
If the user did not confirm the page navigation, then the user agent refused to allow the document to be unloaded.
- If this algorithm was invoked by another instance of the "prompt to unload a document" algorithm (i.e., through the steps below that invoke this algorithm for all descendant browsing contexts), then jump to the step labeled end.
- Let descendants be the list of the descendant browsing
contexts of the
Document
. -
If descendants is not an empty list, then for each browsing context b in descendants run the following substeps:
- Prompt to unload the active document of the browsing context b. If the user refused to allow the document to be unloaded, then the user implicitly also refused to allow this document to be unloaded; jump to the step labeled end.
- If the salvageable state of the active document of the browsing context b is false, then set the salvageable state of this document to false also.
- End: Decrease the
Document
's ignore-opens-during-unload counter by one.
When a user agent is to unload a document, it must run the following steps. These
steps are passed an argument, recycle, which is either true or false,
indicating whether the Document
object is going to be re-used. (This is set by the document.open()
method.)
- Increase the event loop’s termination nesting level by one.
- Increase the
Document
's ignore-opens-during-unload counter by one. - If the
Document
's page showing flag is false, then jump to the step labeled unload event below (i.e., skip firing thepagehide
event and don’t rerun the unloading document visibility change steps). - Set the
Document
's page showing flag to false. - Fire a trusted event with the name
pagehide
at theWindow
object of theDocument
, with target override set to theDocument
object, using thePageTransitionEvent
interface, with thepersisted
attribute initialized to true if theDocument
object’s salvageable state is true, and false otherwise. This event must not bubble, must not be cancelable, and has no default action. -
Run any unloading document visibility change steps for
Document
that are defined by other applicable specifications.This is specifically intended for use by the Page Visibility specification. [PAGE-VISIBILITY]
- Unload event: If the
Document
's fired unload flag is false, fire a simple event namedunload
at theDocument
'sWindow
object, with target override set to theDocument
object. - Decrease the event loop’s termination nesting level by one.
- If any event listeners were triggered by the earlier unload event step, then set
the
Document
object’s salvageable state to false and set theDocument
's fired unload flag to true. - Run any unloading document cleanup steps for
Document
that are defined by this specification and other applicable specifications. - If this algorithm was invoked by another instance of the "unload a document" algorithm (i.e., by the steps below that invoke this algorithm for all descendant browsing contexts), then jump to the step labeled end.
- Let descendants be the list of the descendant browsing
contexts of the
Document
. -
If descendants is not an empty list, then for each browsing context b in descendants run the following substeps:
- Unload the active document of the browsing context b with the recycle parameter set to false.
- If the salvageable state of the active document of the browsing context b is false, then set the salvageable state of this document to false also.
- If both the
Document
's salvageable state and recycle are false, then theDocument
's browsing context must discard theDocument
. - End: Decrease the
Document
's ignore-opens-during-unload counter by one.
This specification defines the following unloading document cleanup steps. Other specifications can define more.
-
Make disappear any
WebSocket
objects that were created by theWebSocket()
constructor from theDocument
'sWindow
object.If this affected any
WebSocket
objects, then setDocument
's salvageable state to false. - If the
Document
's salvageable state is false, forcibly close anyEventSource
objects that whose constructor was invoked from theDocument
'sWindow
object. - If the
Document
's salvageable state is false, empty theDocument
'sWindow
’s list of active timers.
6.7.11.1. The BeforeUnloadEvent
interface
interface BeforeUnloadEvent : Event { attribute DOMString returnValue; };
- event .
returnValue
[ = value ] -
Returns the current return value of the event (the message to show the user).
Can be set, to update the message.
There are no BeforeUnloadEvent
-specific initialization methods.
The returnValue
attribute
represents the message to show the user. When the event is created, the attribute must be set to
the empty string. On getting, it must return the last value it was set to. On setting, the
attribute must be set to the new value.
6.7.12. Aborting a document load
If a Document
is aborted, the user agent must
run the following steps:
- Abort the active
documents of every child browsing context. If this results in any of those
Document
objects having their salvageable state set to false, then set thisDocument
's salvageable state to false also. - Cancel any instances of the fetch algorithm in the
context of this
Document
, discarding any tasks queued for them, and discarding any further data received from the network for them. If this resulted in any instances of the fetch algorithm being canceled or any queued tasks or any network data getting discarded, then set theDocument
's salvageable state to false. - If the
Document
has an active parser, then abort that parser and set theDocument
's salvageable state to false.
User agents may allow users to explicitly invoke the abort a
document algorithm for a Document
. If the user does so, then, if that Document
is an active document, the user agent should queue a
task to fire a simple event named abort
at
that Document
's Window
object before invoking the abort algorithm.
6.7.13. Browser state
[NoInterfaceObject, Exposed=(Window, Worker)] interface NavigatorOnLine { readonly attribute boolean onLine; };
- window .
navigator
.onLine
-
Returns false if the user agent is definitely offline (disconnected from the network). Returns true if the user agent might be online.
The events
online
andoffline
are fired when the value of this attribute changes.
The navigator.onLine
attribute must return
false if the user agent will not contact the network when the user follows links or when a script
requests a remote page (or knows that such an attempt would fail), and must return true
otherwise.
When the value that would be returned by the navigator.onLine
attribute of a Window
or WorkerGlobalScope
changes from true to false, the user agent must queue a
task to fire a simple event named offline
at the Window
or WorkerGlobalScope
object.
On the other hand, when the value that would be returned by the navigator.onLine
attribute of a Window
or WorkerGlobalScope
changes from false to true, the user agent must queue a
task to fire a simple event named online
at
the Window
or WorkerGlobalScope
object.
The task source for these tasks is the networking task source.
This attribute is inherently unreliable. A computer can be connected to a network without having Internet access.
<!DOCTYPE HTML> <html> <head> <title>Online status</title> <script> function updateIndicator() { document.getElementById('indicator').textContent = navigator.onLine ? 'online' : 'offline'; } </script> </head> <body onload="updateIndicator()" ononline="updateIndicator()" onoffline="updateIndicator()"> <p>The network is: <span>(state unknown)</span> </body> </html>
7. Web application APIs
7.1. Scripting
7.1.1. Introduction
Various mechanisms can cause author-provided executable code to run in the context of a document. These mechanisms include, but are probably not limited to:
-
Processing of
script
elements. -
Navigating to
javascript:
URLs. -
Event handlers, whether registered through the DOM using
addEventListener()
, by explicit event handler content attributes, by event handler IDL attributes, or otherwise. -
Processing of technologies like SVG that have their own scripting features.
7.1.2. Enabling and disabling scripting
Scripting is enabled in a browsing context when all of the following conditions are true:
-
The user agent supports scripting.
-
The user has not disabled scripting for this browsing context at this time. (User agents may provide users with the option to disable scripting globally, or in a finer-grained manner, e.g. on a per-origin basis.)
-
The browsing context’s active document’s active sandboxing flag set does not have its sandboxed scripts browsing context flag set.
Scripting is disabled in a browsing context when any of the above conditions are false (i.e., when scripting is not enabled).
Scripting is enabled for a node if the node’s node document has a browsing context, and scripting is enabled in that browsing context.
Scripting is disabled for a node if there is no such browsing context, or if scripting is disabled in that browsing context.
7.1.3. Processing model
7.1.3.1. Definitions
A script is one of two possible structures. All scripts have:
-
A settings object
-
An environment settings object, containing various settings that are shared with other scripts in the same context.
A classic script additionally has:
-
A Source text
-
A string containing a block of executable code to be evaluated as a JavaScript Script.
-
Optionally, a muted errors flag
-
A flag which, if set, means that error information will not be provided for errors in this script (used to mute errors for cross-origin scripts, since that can leak private information).
An environment settings object specifies algorithms for obtaining the following:
-
A realm execution context
-
A JavaScript execution context shared by all
script
elements that use this settings object, i.e. all scripts in a given JavaScript realm. When we run a classic script this execution context becomes the top of the JavaScript execution context stack, on top of which another execution context specific to the script in question is pushed. (This setup ensures ParseScript knows which Realm to use.) -
A responsible browsing context
-
A browsing context that is assigned responsibility for actions taken by the scripts that use this environment settings object.
When a script creates and navigates a new top-level browsing context, the
opener
attribute of the new browsing context’sWindow
object will be set to the responsible browsing context’sWindowProxy
object. -
A responsible event loop
-
An event loop that is used when it would not be immediately clear what event loop to use.
-
A responsible document
-
A
Document
that is assigned responsibility for actions taken by the scripts that use this environment settings object.For example, the address of the responsible document is used to set the address of the
Document
after it has been reset usingopen()
.If the responsible event loop is not a browsing context event loop, then the environment settings object has no responsible document.
-
An API URL character encoding
-
A character encoding used to encode URLs by APIs called by scripts that use this environment settings object.
-
An API base URL
-
An URL used by APIs called by scripts that use this environment settings object to parse URLs.
-
An origin
-
An instrument used in security checks.
-
A creation URL
-
An absolute URL representing the location of the resource with which the environment settings object is associated. Note that this URL might be distinct from the responsible document’s address, due to mechanisms such as
history.pushState()
. -
An HTTPS state
-
An HTTPS state value representing the security properties of the network channel used to deliver the resource with which the environment settings object is associated.
An environment settings object also has an outstanding rejected promises weak set and an about-to-be-notified rejected promises list, used to track unhandled promise rejections. The outstanding rejected promises weak set must not create strong references to any of its members, and implementations are free to limit its size, e.g., by removing old entries from it when new ones are added.
7.1.3.2. Fetching scripts
The various script-fetching algorithms below have two hooks that may be customized by their callers:
-
Set up the request, which takes a request which it may modify before the algorithm continues
-
Process the response, which takes a response and must either return
true
orfalse
to indicate success or failure, respectively
Service Workers is an example of a specification that runs these algorithms with its own options for the hooks. [SERVICE-WORKERS]
To fetch a classic script for a script
element element, given a url, a CORS setting, a cryptographic nonce, a parser state, a settings object, and a character encoding, run
these steps. The algorithm will asynchronously complete with either null (on failure) or a new classic script (on success).
-
Let request be the result of creating a potential-CORS request given url and CORS setting.
-
Set request’s client to settings object, its type to "
script
", its destination to "script
", its cryptographic nonce metadata to cryptographic nonce, and its parser metadata to parser state. -
If the caller specified custom steps to set up the request, perform them on request.
-
Fetch request.
-
Return from this algorithm, and run the remaining steps as part of the fetch’s process response for the response response.
response can be either CORS-same-origin or CORS-cross-origin. This only affects how error reporting happens.
-
If response’s type is "
error
", or response’s status is not an ok status, asynchronously complete this algorithm with null, and abort these steps. -
If the caller specified custom steps to process the response, perform them on response. If they return false, complete this algorithm with null, and abort these steps.
-
If response’s Content-Type metadata, if any, specifies a character encoding, and the user agent supports that encoding, then set character encoding to that encoding (ignoring the passed-in value).
-
Let source text be the result of decoding response’s body to Unicode, using character encoding as the fallback encoding.
The decode algorithm overrides character encoding if the file contains a BOM.
-
Let script be the result of creating a classic script using source text and settings object.
If response was CORS-cross-origin, then pass the muted errors flag to the create a classic script algorithm as well.
-
Asynchronously complete this algorithm with script.
To fetch a classic worker script given a url, a referrer, a settings object, and a destination, run these steps. The algorithm will asynchronously complete with either null (on failure) or a new classic script (on success).
-
Let request be a new request whose url is url, client is settings object, type is "
script
", destination is destination, referrer is referrer, mode is "same-origin
", credentials mode is "same-origin
", parser metadata is "not parser-inserted
", and whose use-URL-credentials flag is set. -
If the caller specified custom steps to set up the request, perform them on request.
-
Fetch request.
-
Return from this algorithm, and run the remaining steps as part of the fetch’s process response for the response response.
-
If response’s type is "
error
", or response’s status is not an ok status, asynchronously complete this algorithm with null, and abort these steps. -
If the caller specified custom steps to process the response, perform them on response. If they return false, complete this algorithm with null, and abort these steps.
-
Let source text be the result of UTF-8 decoding response’s body.
-
Let script be the result of creating a classic script using source text and settings object.
-
Asynchronously complete this algorithm with script.
7.1.3.3. Creating scripts
To create a classic script, given some script source, an environment settings object, and an optional muted errors flag:
-
Let script be a new classic script that this algorithm will subsequently initialize.
-
Set script’s settings object to the environment settings object provided.
-
If scripting is disabled for the given environment settings object’s responsible browsing context, set script’s source text to the empty string. Otherwise, set script’s source text to the supplied script source.
-
If the muted errors flag was set, then set script’s muted errors flag.
-
Return script.
7.1.3.4. Calling scripts
To run a classic script given a classic script s and an optional rethrow errors flag:
-
Let settings be the settings object of s.
-
Check if we can run script with settings. If this returns "do not run", then return undefined and abort these steps.
-
Let realm be settings’s Realm.
-
Prepare to run script with settings.
-
Let result be ParseScript(s’s source text, realm, s).
-
If result is a List of errors, set result to the first element of result and go to the step labeled error.
-
Let evaluationStatus be ScriptEvaluation(result).
-
If evaluationStatus is an abrupt completion, set result to evaluationStatus.[[value]] and go to the next step (labeled Error). If evaluationStatus is a normal completion, or if ScriptEvaluation does not complete because the user agent has aborted the running script, skip to the step labeled Cleanup.
-
Error: At this point result must be an exception. Perform the following steps:
-
If the rethrow errors flag is set and s’s muted errors flag is not set, rethrow result.
-
If the rethrow errors flag is set and s’s muted errors flag is set, throw a
NetworkError
exception. -
If the rethrow errors flag is not set, report the exception given by result for the script s.
-
-
Cleanup: Clean up after running script with settings.
-
If evaluationStatus exists and is a normal completion, return evaluationStatus.[[value]]. Otherwise, script execution was unsuccessful, either because an error occurred during parsing, or an exception occurred during evaluation, or because it was aborted prematurely.
The steps to check if we can run script with an environment settings object settings are as follows. They return either "run" or "do not run".
-
If the global object specified by settings is a
Window
object whoseDocument
object is not fully active, then return "do not run" and abort these steps. -
If scripting is disabled for the responsible browsing context specified by settings, then return "do not run" and abort these steps.
-
Return "run".
The steps to prepare to run script with an environment settings object settings are as follows:
-
Increment settings’s realm execution context’s entrance counter by one.
-
Push settings’s realm execution context onto the JavaScript execution context stack; it is now the running JavaScript execution context.
The steps to clean up after running script with an environment settings object settings are as follows:
-
Assert: settings’s realm execution context is the running JavaScript execution context.
-
Decrement settings’s realm execution context’s entrance counter by one.
-
Remove settings’s realm execution context from the JavaScript execution context stack.
-
If the JavaScript execution context stack is now empty, run the global script clean-up jobs. (These cannot run scripts.)
-
If the JavaScript execution context stack is now empty, perform a microtask checkpoint. (If this runs scripts, these algorithms will be invoked reentrantly.)
These algorithms are not invoked by one script directly calling another, but they can be invoked reentrantly in an indirect manner, e.g., if a script dispatches an event which has event listeners registered.
The running script is the script in the [[HostDefined]] field in the Script component of the running JavaScript execution context.
Each unit of related similar-origin browsing contexts has a global script
clean-up jobs list, which must initially be empty. A global script clean-up job cannot run
scripts, and cannot be sensitive to the order in which other clean-up jobs are executed. The File
API uses this to release blob:
URLs. [FILEAPI]
When the user agent is to run the global script clean-up jobs, the user agent must perform each of the jobs in the global script clean-up jobs list and then empty the list.
7.1.3.5. Realms, settings objects, and global objects
A global object is a JavaScript object that is the [[globalObject]] field of a JavaScript realm.
In this specification, all JavaScript realms are initialized with global objects that are either Window
or WorkerGlobalScope
objects.
There is always a 1:1:1 mapping between JavaScript realms, global objects, and environment settings objects:
-
A JavaScript realm has a [[HostDefined]] field, which contains the Realm’s settings object.
-
A JavaScript realm has a [[globalObject]] field, which contains the Realm’s global object.
-
Each global object in this specification is created during the initialization of a corresponding JavaScript realm, known as the global object’s Realm.
-
Each global object in this specification is created alongside a corresponding environment settings object, known as its relevant settings object.
-
An environment settings object’s realm execution context’s Realm component is the environment settings object’s Realm.
-
An environment settings object’s Realm then has a [[globalObject]] field, which contains the environment settings object’s global object.
When defining algorithm steps throughout this specification, it is often important to indicate what JavaScript realm is to be used—or, equivalently, what global object or environment settings object is to be used. In general, there are at least four possibilities:
-
Entry
-
This corresponds to the script that initiated the currently running script action: i.e., the function or script that the user agent called into when it called into author code.
-
Incumbent
-
This corresponds to the most-recently-entered author function or script on the stack.
-
Current
-
This corresponds to the currently-running function object, including built-in user-agent functions which might not be implemented as JavaScript. (It is derived from the current JavaScript realm.)
-
Relevant
-
Every platform object has a relevant Realm. When writing algorithms, the most prominent platform object whose relevant Realm might be important is the
this
value of the currently-running function object. In some cases, there can be other important relevant Realms, such as those of any arguments.
Note how the entry, incumbent, and current concepts are usable without qualification, whereas the relevant concept must be applied to a particular platform object.
a.html
being loaded in a browser window, b.html
being loaded in an iframe
as shown, and c.html
and d.html
omitted (they can simply be empty documents):
<!-- a/a.html --> <!DOCTYPE HTML> <html lang="en"> <title>Entry page</title> <iframe src="b.html"></iframe> <button onclick="frames[0].hello()">Hello</button> <!-- b.html --> <!DOCTYPE HTML> <html lang="en"> <title>Incumbent page</title> <iframe src="c.html" id="c"></iframe> <iframe src="d.html" id="d"></iframe> <script> const c = document.querySelector("#c").contentWindow; const d = document.querySelector("#d").contentWindow; window.hello = () => { c.print.call(d); }; </script>
Each page has its own browsing context, and thus its own JavaScript realm, global object, and environment settings object.
When the print()
method is called in response to pressing the button in a.html
, then:
-
The entry Realm is that of
a.html
. -
The incumbent Realm is that of
b.html
. -
The current Realm is that of
c.html
(since it is theprint()
method fromc.html
whose code is running). -
The relevant Realm of the object on which the
print()
method is being called is that ofd.html
.
The incumbent and entry concepts should not be used by new specifications, and we are considering whether we can remove almost all existing uses
Currently, the incumbent concept is used in some security checks, and the entry concept is sometimes used to obtain, amongst other things, the API base URL to parse a URL, used in scripts running in that unit of related similar-origin browsing contexts.
In general, the current concept is what should be used by specifications going forward. There is an important exception, however. If an algorithm is creating an object that is to be persisted and returned multiple times (instead of simply returned to author code right away, and never vended again), it should use the relevant concept with regard to the object on which the method in question is being executed. This prevents cross-realm calls from causing an object to store objects created in the "wrong" realm.
navigator.getBattery()
method creates promises in the relevant Realm for
the Navigator
object on which it is invoked. This has the following impact: [BATTERY-STATUS]
<!-- outer.html --> <!DOCTYPE html> <html lang="en"> <title>Relevant Realm demo: outer page</title> <script> function doTest() { const promise = navigator.getBattery.call(frames[0].navigator); console.log(promise instanceof Promise); // logs false console.log(promise instanceof frames[0].Promise); // logs true frames[0].hello(); } </script> <iframe src="inner.html" onload="doTest()"></iframe> <!-- inner.html --> <!DOCTYPE html> <html lang="en"> <title>Relevant Realm demo: inner page</title> <script> function hello() { const promise = navigator.getBattery(); console.log(promise instanceof Promise); // logs true console.log(promise instanceof parent.Promise); // logs false } </script>
If the algorithm for the getBattery()
method had instead used the current
Realm, all the results would be reversed. That is, after the first call to getBattery()
in outer.html
, the Navigator
object in inner.html
would be permanently storing a Promise
object created in outer.html
’s JavaScript realm, and calls like that inside the hello()
function would thus return a promise from the "wrong" realm. Since this is
undesirable, the algorithm instead uses the relevant Realm, giving the sensible results
indicated in the comments above.
The rest of this section deals with formally defining the entry, incumbent, current, and relevant concepts.
7.1.3.5.1. Entry
All realm execution contexts must contain, as part of their code evaluation state, an entrance counter value, which is initially zero. In the process of calling scripts, this value will be incremented and decremented.
With this in hand, we define the entry execution context to be the most recently pushed entry in the JavaScript execution context stack whose entrance counter value is greater than zero. The entry Realm is the entry execution context’s Realm component.
Then, the entry settings object is the environment settings object of the entry Realm.
Similarly, the entry global object is the global object of the entry Realm.
7.1.3.5.2. Incumbent
The incumbent settings object is determined as follows:
-
Let script be the result of JavaScript’s GetActiveScriptOrModule() abstract operation.
-
If script is null, abort these steps; there is no incumbent settings object.
-
Return the settings object of the
script
in script’s [[HostDefined]] field.
Then, the incumbent Realm is the Realm of the incumbent settings object.
Similarly, the incumbent global object is the global object of the incumbent settings object.
7.1.3.5.3. Current
The JavaScript specification defines the current Realm Record, sometimes abbreviated to the "current Realm". [ECMA-262]
Then, the current settings object is the environment settings object of the current Realm Record.
Similarly, the current global object is the global object of the current Realm Record.
7.1.3.5.4. Relevant
The relevant settings object for a platform object is defined as follows:
- If the object is a global object
- Each global object in this specification is created alongside a corresponding environment settings object; that is its relevant settings object.
- Otherwise
-
The relevant settings object for a non-global platform object o is
the environment settings object whose global object is the global object of the global environment associated with o.
The "global environment associated with" concept is from the olden days, before the modern JavaScript specification and its concept of realms. We expect that as the Web IDL specification gets updated, every platform object will have a Realm associated with it, and this definition can be re-cast in those terms. [ECMA-262] [WEBIDL]
Then, the relevant Realm for a platform object is the Realm of its relevant settings object.
Similarly, the relevant global object for a platform object is the global object of its relevant settings object.
7.1.3.6. Killing scripts
Although the JavaScript specification does not account for this possibility, it’s sometimes
necessary to abort a running script.
This causes any ScriptEvaluation to cease immediately, emptying
the JavaScript execution context stack without triggering any of the normal mechanisms like finally
blocks. [ECMA-262]
User agents may impose resource limitations on scripts, for example CPU quotas, memory limits,
total execution time limits, or bandwidth limitations. When a script exceeds a limit, the user
agent may either throw a QuotaExceededError
exception, abort the script without an
exception, prompt the user, or throttle script execution.
<script> while (true) { /* loop */ } </script>
User agents are encouraged to allow users to disable scripting whenever the user is prompted
either by a script (e.g., using the window.alert()
API) or because
of a script’s actions (e.g., because it has exceeded a time limit).
If scripting is disabled while a script is executing, the script should be terminated immediately.
User agents may allow users to specifically disable scripts just for the purposes of closing a browsing context.
For example, the prompt mentioned in the example above could also offer the
user with a mechanism to just close the page entirely, without running any unload
event handlers.
7.1.3.7. Integration with the JavaScript job queue
The JavaScript specification defines the JavaScript job and job queue abstractions in order to specify certain invariants about how promise operations execute with a clean JavaScript execution context stack and in a certain order. However, as of the time of this writing the definition of EnqueueJob in that specification are not sufficiently flexible to integrate with HTML as a host environment. [ECMA-262]
This is not strictly true. It is in fact possible, by taking liberal advantage of the many "implementation defined" sections of the algorithm, to contort it to our purposes. However, the end result is a mass of messy indirection and workarounds that essentially bypasses the job queue infrastructure entirely, albeit in a way that is technically sanctioned within the bounds of implementation-defined behavior. We do not take this path, and instead introduce the following willful violation.
As such, user agents must instead use the following definition in place of that in the JavaScript specification. These ensure that the promise jobs enqueued by the JavaScript specification are properly integrated into the user agent’s event loops.
7.1.3.7.1. EnqueueJob(queueName, job, arguments)
When the JavaScript specification says to call the EnqueueJob abstract operation, the following algorithm must be used in place of JavaScript’s EnqueueJob:
-
Assert: queueName is
"PromiseJobs"
. ("ScriptJobs"
must not be used by user agents.) -
Let settings be the settings object of job.[[Realm]]
-
Queue a microtask, on settings’s responsible event loop, to perform the following steps:
-
Check if we can run script with settings. If this returns "do not run" then abort these steps.
-
Prepare to run script with settings.
-
Let result be the result of performing the abstract operation specified by job, using the elements of arguments as its arguments.
-
Clean up after running script with settings.
-
If result is an abrupt completion, report the exception given by result.[[value]].
-
7.1.3.8. Runtime script errors
When the user agent is required to report an error for a particular script script with a particular position line:col, using a particular target target, it must run these steps, after which the error is either handled or not handled:
-
If target is in error reporting mode, then abort these steps; the error is not handled.
-
Let target be in error reporting mode.
-
Let message be a user-agent-defined string describing the error in a helpful manner.
-
Let error object be the object that represents the error: in the case of an uncaught exception, that would be the object that was thrown; in the case of a JavaScript error that would be an
Error
object. If there is no corresponding object, then the null value must be used instead. -
Let location be an absolute URL that corresponds to the resource from which script was obtained.
The resource containing the script will typically be the file from which the
Document
was parsed, e.g., for inlinescript
elements or event handler content attributes; or the JavaScript file that the script was in, for external scripts. Even for dynamically-generated scripts, user agents are strongly encouraged to attempt to keep track of the original source of a script. For example, if an external script uses thedocument.write()
API to insert an inlinescript
element during parsing, the URL of the resource containing the script would ideally be reported as being the external script, and the line number might ideally be reported as the line with thedocument.write()
call or where the string passed to that call was first constructed. Naturally, implementing this can be somewhat non-trivial.User agents are similarly encouraged to keep careful track of the original line numbers, even in the face of
document.write()
calls mutating the document as it is parsed, or event handler content attributes spanning multiple lines. -
If script has muted errors, then set message to "
Script error.
", set location to the empty string, set line and col to 0, and set error object to null. -
Let event be a new trusted
ErrorEvent
object that does not bubble but is cancelable, and which has the event nameerror
. -
Initialize event’s
message
attribute to message. -
Initialize event’s
filename
attribute to location. -
Initialize event’s
lineno
attribute to line. -
Initialize event’s
colno
attribute to col. -
Initialize event’s
error
attribute to error object. -
Dispatch event at target.
-
Let target no longer be in error reporting mode.
-
If event was canceled, then the error is handled. Otherwise, the error is not handled.
Returning true cancels event per the event handler processing algorithm.
7.1.3.8.1. Runtime script errors in documents
When the user agent is to report an exception E, the user agent must report the error for the relevant script, with the problematic position (line number and column number) in the resource containing the script, using the global object specified by the script’s settings object as the target. If the error is still not handled after this, then the error may be reported to a developer console.
7.1.3.8.2. The ErrorEvent
interface
[Constructor(DOMString type, optional ErrorEventInit eventInitDict), Exposed=(Window, Worker)] interface ErrorEvent : Event { readonly attribute DOMString message; readonly attribute DOMString filename; readonly attribute unsigned long lineno; readonly attribute unsigned long colno; readonly attribute any error; };
dictionary ErrorEventInit : EventInit { DOMString message = ""; DOMString filename = ""; unsigned long lineno = 0; unsigned long colno = 0; any error = null; };
The message
attribute must return the
value it was initialized to. It represents the error message.
The filename
attribute must return the value it
was initialized to. It represents the absolute URL of the script in which the error
originally occurred.
The lineno
attribute must return the value it
was initialized to. It represents the line number where the error occurred in the script.
The colno
attribute must return the value it
was initialized to. It represents the column number where the error occurred in the script.
The error
attribute must return the value it
was initialized to. Where appropriate, it is set to the object representing the error
(e.g., the exception object in the case of an uncaught DOM exception).
7.1.3.9. Unhandled promise rejections
There is only one known native implementation of the unhandledrejection
and rejectionhandled
events (Chrome/Blink). Therefore these features should not be relied upon.
In addition to synchronous runtime script errors, scripts may experience asynchronous
promise rejections, tracked via the unhandledrejection
and rejectionhandled
events.
When the user agent is to notify about rejected promises on a given environment settings object settings object, it must run these steps:
-
Let list be a copy of settings object’s about-to-be-notified rejected promises list.
-
If list is empty, abort these steps.
-
Clear settings object’s about-to-be-notified rejected promises list.
-
Queue a task to run the following substep:
-
For each promise p in list:
-
If p’s [[PromiseIsHandled]] internal slot is true, continue to the next iteration of the loop.
-
Let event be a new trusted
PromiseRejectionEvent
object that does not bubble but is cancelable, and which has the event nameunhandledrejection
. -
Initialise event’s
promise
attribute to p. -
Initialise event’s
reason
attribute to the value of p’s [[PromiseResult]] internal slot. -
Dispatch event at settings object’s global object.
-
If the event was canceled, then the promise rejection is handled. Otherwise, the promise rejection is not handled.
-
If p’s [[PromiseIsHandled]] internal slot is false, add p to settings object’s outstanding rejected promises weak set.
-
-
This algorithm results in promise rejections being marked as handled or not handled. These concepts parallel handled and not handled script errors. If a rejection is still not handled after this, then the rejection may be reported to a developer console.
7.1.3.9.1. The HostPromiseRejectionTracker implementation
ECMAScript contains an implementation-defined HostPromiseRejectionTracker(promise, operation) abstract operation. User agents must use the following implementation: [ECMA-262]
-
Let script be the running script.
-
If script has muted errors, terminate these steps.
-
Let settings object be script’s settings object.
-
If operation is
"reject"
,-
Add promise to settings object’s about-to-be-notified rejected promises list.
-
-
If operation is
"handle"
,-
If settings object’s about-to-be-notified rejected promises list contains promise, remove promise from that list and abort these steps.
-
If settings object’s outstanding rejected promises weak set does not contain promise, abort these steps.
-
Remove promise from settings object’s outstanding rejected promises weak set.
-
Queue a task to run the following steps:
-
Let event be a new trusted
PromiseRejectionEvent
object that does not bubble and is not cancelable, and which has the event namerejectionhandled
. -
Initialise event’s
promise
attribute to promise. -
Initialise event’s
reason
attribute to the value of promise’s [[PromiseResult]] internal slot. -
Dispatch event at settings object’s global object.
-
-
7.1.3.9.2. The PromiseRejectionEvent
interface
[Constructor(DOMString type, PromiseRejectionEventInit eventInitDict), Exposed=(Window,Worker)] interface PromiseRejectionEvent : Event { readonly attribute Promise<any> promise; readonly attribute any reason; };
dictionary PromiseRejectionEventInit : EventInit { required Promise<any> promise; any reason; };
The promise
attribute must return
the value it was initialized to. It represents the promise which this notification is about.
The reason
attribute must return
the value it was initialized to. It represents the rejection reason for the promise.
7.1.3.10. HostEnsureCanCompileStrings(callerRealm, calleeRealm)
JavaScript contains an implementation-defined HostEnsureCanCompileStrings(callerRealm, calleeRealm) abstract operation. User agents must use the following implementation: [ECMA-262]
-
Perform ? EnsureCSPDoesNotBlockStringCompilation(callerRealm, calleeRealm). [CSP3]
7.1.4. Event loops
7.1.4.1. Definitions
To coordinate events, user interaction, scripts, rendering, networking, and so forth, user agents
must use event loops as described in this section. There
are two kinds of event loops: those for browsing contexts, and those for workers
.
There must be at least one browsing context event loop per user agent, and at most one per unit of related similar-origin browsing contexts.
When there is more than one event loop for a unit of related browsing contexts, complications arise when a browsing context in that group is navigated such that it switches from one unit of related similar-origin browsing contexts to another. This specification does not currently describe how to handle these complications.
A browsing context event loop always has at least one browsing context. If such an event loop’s browsing contexts all go away, then the event loop goes away as well. A browsing context always has an event loop coordinating its activities.
Worker event loops are simpler: each worker has one event loop, and the worker processing model manages the event loop’s lifetime.
An event loop has one or more task queues. A task queue is an ordered list of tasks, which are algorithms that are responsible for such work as:
-
Events
-
Dispatching an
Event
object at a particularEventTarget
object is often done by a dedicated task.Not all events are dispatched using the task queue, many are dispatched during other tasks.
-
Parsing
-
The HTML parser tokenizing one or more bytes, and then processing any resulting tokens, is typically a task.
-
Callbacks
-
Calling a callback is often done by a dedicated task.
-
Using a resource
-
When an algorithm fetches a resource, if the fetching occurs in a non-blocking fashion then the processing of the resource once some or all of the resource is available is performed by a task.
-
Reacting to DOM manipulation
-
Some elements have tasks that trigger in response to DOM manipulation, e.g., when that element is inserted into the document.
Each task in a browsing context event loop is associated with a Document
;
if the task was queued in the context of an element, then it is the element’s node document; if the task was queued in the context of a browsing context, then it
is the browsing context’s active document at the time the task was queued; if the
task was queued by or for a script then the document is the responsible document specified by the script’s settings object.
A task is intended for a specific event loop: the event loop that is handling tasks for the task’s associated Document
or Worker
.
When a user agent is to queue a task, it must add the given task to one of the task queues of the relevant event loop.
Each task is defined as coming from a specific task source. All the tasks from
one particular task source and destined to a particular event loop (e.g., the
callbacks generated by timers of a Document
, the events fired for mouse movements over that Document
, the tasks queued for the parser of that Document
) must always be added
to the same task queue, but tasks from different task sources may be placed
in different task queues.
For example, a user agent could have one task queue for mouse and key events (the user interaction task source), and another for everything else. The user agent could then give keyboard and mouse events preference over other tasks three quarters of the time, keeping the interface responsive but not starving other task queues, and never processing events from any one task source out of order.
Each event loop has a currently running task. Initially, this is null. It is used to handle reentrancy. Each event loop also has a performing a microtask checkpoint flag, which must initially be false. It is used to prevent reentrant invocation of the perform a microtask checkpoint algorithm.
7.1.4.2. Processing model
An event loop must continually run through the following steps for as long as it exists:
-
Select the oldest task on one of the event loop’s task queues, if any, ignoring, in the case of a browsing context event loop, tasks whose associated
Document
s are not fully active. The user agent may pick any task queue. If there is no task to select, then jump to the Microtasks step below. -
Set the event loop’s currently running task to the task selected in the previous step.
-
Run: Run the selected task.
-
Set the event loop’s currently running task back to null.
-
Remove the task that was run in the Run step above from its task queue.
-
Microtasks: Perform a microtask checkpoint.
-
Update the rendering: If this event loop is a browsing context event loop (as opposed to a
Worker
event loop), then run the following substeps.-
Let now be the value that would be returned by the
Performance
object’snow()
method. [HR-TIME-2] -
Let docs be the list of
Document
objects associated with the event loop in question, sorted arbitrarily except that the following conditions must be met:-
Any
Document
B that is nested through aDocument
A must be listed after A in the list. -
If there are two documents A and B whose browsing contexts are both nested browsing contexts and their browsing context containers are both elements in the same
Document
C, then the order of A and B in the list must match the relative tree order of their respective browsing context containers in C.
In the steps below that iterate over docs, each
Document
must be processed in the order it is found in the list. -
-
If there is a top-level browsing context B that the user agent believes would not benefit from having its rendering updated at this time, then remove from docs all
Document
objects whose browsing context’s top-level browsing context is B.Whether a top-level browsing context would benefit from having its rendering updated depends on various factors, such as the update frequency. For example, if the browser is attempting to achieve a 60 Hz refresh rate, then these steps are only necessary every 60th of a second (about 16.7ms). If the browser finds that a top-level browsing context is not able to sustain this rate, it might drop to a more sustainable 30Hz for that set of
Document
s, rather than occasionally dropping frames. (This specification does not mandate any particular model for when to update the rendering.) Similarly, if a top-level browsing context is in the background, the user agent might decide to drop that page to a much slower 4Hz, or even less.Another example of why a browser might skip updating the rendering is to ensure certain tasks are executed immediately after each other, with only microtask checkpoints interleaved (and without, e.g., animation frame callbacks interleaved). For example, a user agent might wish to coalesce timer callbacks together, with no intermediate rendering updates.
-
If there are a nested browsing contexts B that the user agent believes would not benefit from having their rendering updated at this time, then remove from docs all
Document
objects whose browsing context is in B.As with top-level browsing contexts, a variety of factors can influence whether it is profitable for a browser to update the rendering of nested browsing contexts. For example, a user agent might wish to spend less resources rendering third-party content, especially if it is not currently visible to the user or if resources are constrained. In such cases, the browser could decide to update the rendering for such content infrequently or never.
-
For each fully active
Document
in docs, run the resize steps for thatDocument
, passing in now as the timestamp. [CSSOM-VIEW] -
For each fully active
Document
in docs, run the scroll steps for thatDocument
, passing in now as the timestamp. [CSSOM-VIEW] -
For each fully active
Document
in docs, evaluate media queries and report changes for thatDocument
, passing in now as the timestamp. [CSSOM-VIEW] -
For each fully active
Document
in docs, run CSS animations and send events for thatDocument
, passing in now as the timestamp. [CSS3-ANIMATIONS] -
For each fully active
Document
in docs, run the fullscreen rendering steps for thatDocument
, passing in now as the timestamp. [FULLSCREEN] -
For each fully active
Document
in docs, run the animation frame callbacks for thatDocument
, passing in now as the timestamp. -
For each fully active
Document
in docs, update the rendering or user interface of thatDocument
and its browsing context to reflect the current state.
-
-
If this is a
Worker
event loop (i.e., one running for aWorkerGlobalScope
), but there are no tasks in the event loop’s task queues and theWorkerGlobalScope
object’s closing flag is true, then destroy the event loop, aborting these steps, resuming the run a worker steps. -
Return to the first step of the event loop.
Each event loop has a microtask queue. A microtask is a task that is originally to be queued on the microtask queue rather than a task queue. There are two kinds of microtasks: solitary callback microtasks, and compound microtasks.
This specification only has solitary callback microtasks. Specifications that use compound microtasks have to take extra care to wrap callbacks to handle spinning the event loop.
When an algorithm requires a microtask to be queued, it must be appended to the relevant event loop’s microtask queue; the task source of such a microtask is the microtask task source.
It is possible for a microtask to be moved to a regular task queue, if, during its initial execution, it spins the event loop. In that case, the microtask task source is the task source used. Normally, the task source of a microtask is irrelevant.
When a user agent is to perform a microtask checkpoint, if the performing a microtask checkpoint flag is false, then the user agent must run the following steps:
-
Let the performing a microtask checkpoint flag be true.
-
Microtask queue handling: If the event loop’s microtask queue is empty, jump to the Done step below.
-
Select the oldest microtask on the event loop’s microtask queue.
-
Set the event loop’s currently running task to the task selected in the previous step.
-
Run: Run the selected task.
This might involve invoking scripted callbacks, which eventually calls the clean up after running script steps, which call this perform a microtask checkpoint algorithm again, which is why we use the performing a microtask checkpoint flag to avoid reentrancy.
-
Set the event loop’s currently running task back to null.
-
Remove the microtask run in the step above from the microtask queue, and return to the Microtask queue handling step.
-
Done: For each environment settings object whose responsible event loop is this event loop, notify about rejected promises on that environment settings object.
-
Let the performing a microtask checkpoint flag be false.
If, while a compound microtask is running, the user agent is required to execute a compound microtask subtask to run a series of steps, the user agent must run the following steps:
-
Let parent be the event loop’s currently running task (the currently running compound microtask).
-
Let subtask be a new task that consists of running the given series of steps. The task source of such a microtask is the microtask task source. This is a compound microtask subtask.
-
Set the event loop’s currently running task to subtask.
-
Run subtask.
-
Set the event loop’s currently running task back to parent.
When an algorithm running in parallel is to await a stable state, the user agent must queue a microtask that runs the following steps, and must then stop executing (execution of the algorithm resumes when the microtask is run, as described in the following steps):
-
Run the algorithm’s synchronous section.
-
Resumes execution of the algorithm in parallel, if appropriate, as described in the algorithm’s steps.
Steps in synchronous sections are marked with ⌛.
When an algorithm says to spin the event loop until a condition goal is met, the user agent must run the following steps:
-
Let task be the event loop’s currently running task.
This might be a microtask, in which case it is a solitary callback microtask. It could also be a compound microtask subtask, or a regular task that is not a microtask. It will not be a compound microtask.
-
Let task source be task’s task source.
-
Let old stack be a copy of the JavaScript execution context stack.
-
Empty the JavaScript execution context stack.
-
Stop task, allowing whatever algorithm that invoked it to resume, but continue these steps in parallel.
This causes one of the following algorithms to continue: the event loop’s main set of steps, the perform a microtask checkpoint algorithm, or the execute a compound microtask subtask algorithm to continue.
-
Wait until the condition goal is met.
-
Queue a task to continue running these steps, using the task source task source. Wait until this new task runs before continuing these steps.
-
Replace the JavaScript execution context stack with the old stack.
-
Return to the caller.
Some of the algorithms in this specification, for historical reasons, require the user agent to pause while running a task until a condition goal is met. This means running the following steps:
-
If necessary, update the rendering or user interface of any
Document
or browsing context to reflect the current state. -
Wait until the condition goal is met. While a user agent has a paused task, the corresponding event loop must not run further tasks, and any script in the currently running task must block. User agents should remain responsive to user input while paused, however, albeit in a reduced capacity since the event loop will not be doing anything.
7.1.4.3. Generic task sources
The following task sources are used by a number of mostly unrelated features in this and other specifications.
-
The DOM manipulation task source
-
This task source is used for features that react to DOM manipulations, such as things that happen in a non-blocking fashion when an element is inserted into the document.
-
The user interaction task source
-
This task source is used for features that react to user interaction, for example keyboard or mouse input.
Events sent in response to user input (e.g.,
click
events) must be fired using tasks queued with the user interaction task source. [UIEVENTS] -
The networking task source
-
This task source is used for features that trigger in response to network activity.
-
The history traversal task source
-
This task source is used to queue calls to
history.back()
and similar APIs.
7.1.5. Events
7.1.5.1. Event handlers
Many objects can have event handlers specified. These act as non-capture event listeners for the object on which they are specified. [DOM]
An event handler has a name, which always starts with
"on
" and is followed by the name of the event for which it is intended.
An event handler has a value, which is either null, or is a callback object, or is an internal raw uncompiled handler. The EventHandler
callback function type describes how
this is exposed to scripts. Initially, an event handler’s value must be set to null.
Event handlers are exposed in one of two ways.
The first way, common to all event handlers, is as an event handler IDL attribute.
The second way is as an event handler content attribute. Event handlers on html elements and some of the event handlers on Window
objects are exposed in this way.
An event handler IDL attribute is an IDL attribute for a specific event handler. The name of the IDL attribute is the same as the name of the event handler.
Event handler IDL attributes, on setting, must set the corresponding event handler to their new value, and on getting, must return the result of getting the current value of the event handler in question (this can throw an exception, in which case the getting propagates it to the caller, it does not catch it).
If an event handler IDL attribute exposes an event handler of an object that doesn’t exist, it must always return null on getting and must do nothing on setting.
This can happen in particular for event handler IDL attribute on body
elements that do not have corresponding Window
objects.
Certain event handler IDL attributes have additional requirements, in particular
the onmessage
attribute of MessagePort
objects.
An event handler content attribute is a content attribute for a specific event handler. The name of the content attribute is the same as the name of the event handler.
Event handler content attributes, when specified, must contain valid JavaScript code which, when parsed, would match the FunctionBody production after automatic semicolon insertion. [ECMA-262]
When an event handler content attribute is set, execute the following steps:
-
If the Should element’s inline behavior be blocked by Content Security Policy? algorithm returns "
Blocked
" when executed upon the attribute’s element "script attribute
", and the attribute’s value, then abort these steps. [CSP3] -
Set the corresponding event handler to an internal raw uncompiled handler consisting of the attribute’s new value and the script location where the attribute was set to this value.
When an event handler content attribute is removed, the user agent must set the corresponding event handler to null.
When an event handler H of an element or object T implementing the EventTarget
interface is first set to a non-null value, the user agent must append an event listener to the list of event listeners associated with T with type set to the event handler event type corresponding to H and callback set to the event handler processing algorithm defined below. [DOM]
The callback is emphatically not the event handler itself. Every event handler ends up registering the same callback the algorithm defined below, which takes care of invoking the right callback, and processing the callback’s return value.
This only happens the first time the event
handler’s value is set. Since listeners are called in the order they were registered, the
order of event listeners for a particular event type will always be first the event listeners
registered with addEventListener()
before
the first time the event handler was set to a non-null value,
then the callback to which it is currently set, if any, and finally the event listeners registered
with addEventListener()
after the
first time the event handler was set to a non-null value.
<button>Start Demo</button> <script> var button = document.getElementById('test'); button.addEventListener('click', function () { alert('ONE') }, false); button.setAttribute('onclick', "alert('NOT CALLED')"); // event handler listener is registered here button.addEventListener('click', function () { alert('THREE') }, false); button.onclick = function () { alert('TWO'); }; button.addEventListener('click', function () { alert('FOUR') }, false); </script>
The interfaces implemented by the event object do not influence whether an event handler is triggered or not.
The event handler processing algorithm for an event handler H and an Event
object E is as follows:
-
Let callback be the result of getting the current value of the event handler H.
-
If callback is null, then abort these steps.
-
Process the
Event
object E as follows:- If E is an
ErrorEvent
object and the event handler IDL attribute’s type isOnErrorEventHandler
- Invoke callback with five arguments, the first one having the value of E’s
message
attribute, the second having the value of E’sfilename
attribute, the third having the value of E’slineno
attribute, the fourth having the value of E’scolno
attribute, the fifth having the value of E’serror
attribute, and with the callback this value set to E’scurrentTarget
. Let return value be the callback’s return value. [WEBIDL] - Otherwise
- Invoke callback with one argument, the value of which is the
Event
object E, with the callback this value set to E’scurrentTarget
. Let return value be the callback’s return value. [WEBIDL]
In this step, invoke means to invoke the Web IDL callback function.
If an exception gets thrown by the callback, end these steps and allow the exception to propagate. (It will propagate to the DOM event dispatch logic, which will then report the exception.)
- If E is an
-
Process return value as follows:
- If the event type is
mouseover
- If the event type is
error
and E is anErrorEvent
object - If the event type is
- If return value is a Web IDL boolean true value, then cancel the event.
- If the event type is
beforeunload
-
The event handler IDL attribute’s type is
OnBeforeUnloadEventHandler
, and the return value will therefore have been coerced into either the value null or a DOMString.If the return value is null, then cancel the event.
Otherwise, if the
Event
object E is aBeforeUnloadEvent
object, and theEvent
object E’sreturnValue
attribute’s value is the empty string, then set thereturnValue
attribute’s value to return value. - Otherwise
- If return value is a Web IDL boolean false value, then cancel the event.
- If the event type is
The EventHandler
callback function type represents a callback used for event handlers. It is
represented in Web IDL as follows:
[TreatNonObjectAsNull] callback EventHandlerNonNull = any (Event event); typedef EventHandlerNonNull? EventHandler;
In JavaScript, any Function
object implements this interface.
<body onload="alert(this)" onclick="alert(this)">
...leads to an alert saying "[object Window]
" when the document is
loaded, and an alert saying "[object HTMLBodyElement]
" whenever the
user clicks something in the page.
The return value of the function affects whether the event is canceled or not:
as described above, if the return value is false, the event is canceled (except for mouseover
events, where the return value has to be true to cancel the event). With beforeunload
events, the value is instead used to determine whether or not to prompt
about unloading the document.
For historical reasons, the onerror
handler has different arguments:
[TreatNonObjectAsNull] callback OnErrorEventHandlerNonNull = any ((Event or DOMString) event, optional DOMString source, optional unsigned long lineno, optional unsigned long column, optional any error); typedef OnErrorEventHandlerNonNull? OnErrorEventHandler;
Similarly, the onbeforeunload
handler has a different return value:
[TreatNonObjectAsNull] callback OnBeforeUnloadEventHandlerNonNull = DOMString? (Event event); typedef OnBeforeUnloadEventHandlerNonNull? OnBeforeUnloadEventHandler;
An internal raw uncompiled handler is a tuple with the following information:
-
An uncompiled script body
-
A location where the script body originated, in case an error needs to be reported
When the user agent is to get the current value of the event handler H, it must run these steps:
-
If H’s value is an internal raw uncompiled handler, run these substeps:
-
If H is an element’s event handler, then let element be the element, and document be the element’s node document.
Otherwise, H is a
Window
object’s event handler: let element be null, and let document be theDocument
most recently associated with thatWindow
object. -
If document does not have a browsing context, or if scripting is enabled for document’s browsing context, then return null.
-
Let body be the uncompiled script body in the internal raw uncompiled handler.
-
Let location be the location where the script body originated, as given by the internal raw uncompiled handler.
-
If element is not null and element has a form owner, let form owner be that form owner. Otherwise, let form owner be null.
-
Let script settings be the environment settings object created for the
Window
object with which document is currently associated. -
If body is not parsable as FunctionBody or if parsing detects an early error, then follow these substeps:
-
Set H’s value to null.
-
Report the error for the appropriate script and with the appropriate position (line number and column number) given by location, using the global object specified by script settings as the target. If the error is still not handled after this, then the error may be reported to a developer console.
-
Return null.
-
-
If body begins with a Directive Prologue that contains a Use Strict Directive then let strict be true, otherwise let strict be false.
-
Let function be the result of calling FunctionCreate, with arguments:
-
kind
-
Normal
-
ParameterList
-
- If H is an
onerror
event handler of aWindow
object - Let the function have five arguments, named
event
,source
,lineno
,colno
, anderror
. - Otherwise
- Let the function have a single argument called
event
.
- If H is an
-
Body
-
The result of parsing body above.
-
Scope
-
-
If H is an element’s event handler, then let Scope be the result of NewObjectEnvironment(document, the global environment).
Otherwise, H is a
Window
object’s event handler: let Scope be the global environment. -
If form owner is not null, let Scope be NewObjectEnvironment(form owner, Scope).
-
If element is not null, let Scope be the NewObjectEnvironment(element, Scope).
-
-
Strict
-
The value of strict.
-
-
Set H’s value to function.
-
-
Return H’s value.
7.1.5.2. Event handlers on elements, Document
objects, and Window
objects
The following are the event handlers (and their corresponding event handler event
types) that must be supported by all html elements, as both event handler content
attributes and event handler IDL attributes; and that must be supported by all Document
and Window
objects, as event handler IDL attributes:
Event handler | Event handler event type |
---|---|
onabort
| abort
|
oncancel
| cancel
|
oncanplay
| canplay
|
oncanplaythrough
| canplaythrough
|
onchange
| change
|
onclick
| click
|
onclose
| close
|
oncontextmenu
| contextmenu
|
oncuechange
| cuechange
|
ondblclick
| dblclick
|
ondrag
| drag
|
ondragend
| dragend
|
ondragenter
| dragenter
|
ondragexit
| dragexit
|
ondragleave
| dragleave
|
ondragover
| dragover
|
ondragstart
| dragstart
|
ondrop
| drop
|
ondurationchange
| durationchange
|
onemptied
| emptied
|
onended
| ended
|
oninput
| input
|
oninvalid
| invalid
|
onkeydown
| keydown
|
onkeypress
| keypress
|
onkeyup
| keyup
|
onloadeddata
| loadeddata
|
onloadedmetadata
| loadedmetadata
|
onloadstart
| loadstart
|
onmousedown
| mousedown
|
onmouseenter
| mouseenter
|
onmouseleave
| mouseleave
|
onmousemove
| mousemove
|
onmouseout
| mouseout
|
onmouseover
| mouseover
|
onmouseup
| mouseup
|
onwheel
| wheel
|
onpause
| pause
|
onplay
| play
|
onplaying
| playing
|
onprogress
| progress
|
onratechange
| ratechange
|
onreset
| reset
|
onseeked
| seeked
|
onseeking
| seeking
|
onselect
| select
|
onshow
| show
|
onstalled
| stalled
|
onsubmit
| submit
|
onsuspend
| suspend
|
ontimeupdate
| timeupdate
|
ontoggle
| toggle
|
onvolumechange
| volumechange
|
onwaiting
| waiting
|
The following are the event handlers (and their corresponding event handler event
types) that must be supported by all html elements other than body
and frameset
elements, as both event handler content attributes and event handler IDL attributes;
that must be supported by all Document
objects, as event handler IDL attributes; and
that must be supported by all Window
objects, as event handler IDL attributes on the Window
objects themselves, and with corresponding event handler content attributes and event handler IDL attributes exposed on all body
and frameset
elements that are
owned by that Window
object’s Document
s:
Event handler | Event handler event type |
---|---|
onblur
| blur
|
onerror
| error
|
onfocus
| focus
|
onload
| load
|
onresize
| resize
|
onscroll
| scroll
|
The following are the event handlers (and their corresponding event handler event
types) that must be supported by Window
objects, as event handler IDL attributes on
the Window
objects themselves, and with corresponding event handler content attributes and event handler IDL attributes exposed on all body
and frameset
elements that are
owned by that Window
object’s Document
s:
Event handler | Event handler event type |
---|---|
onafterprint
| afterprint
|
onbeforeprint
| beforeprint
|
onbeforeunload
| beforeunload
|
onhashchange
| hashchange
|
onlanguagechange
| languagechange
|
onmessage
| message
|
onoffline
| offline
|
ononline
| online
|
onpagehide
| pagehide
|
onpageshow
| pageshow
|
onrejectionhandled
| rejectionhandled
|
onpopstate
| popstate
|
onstorage
| storage
|
onunhandledrejection
| unhandledrejection
|
onunload
| unload
|
The following are the event handlers (and their corresponding event handler event
types) that must be supported by all html elements, as both event handler content
attributes and event handler IDL attributes and that must be supported by all Document
objects, as event handler IDL attributes:
Event handler | Event handler event type |
---|---|
oncut
| cut
|
oncopy
| copy
|
onpaste
| paste
|
The following are the event handlers (and their corresponding event handler event
types) that must be supported on Document
objects as event handler IDL attributes:
Event handler | Event handler event type |
---|---|
onreadystatechange
| readystatechange
|
7.1.5.2.1. IDL definitions
[NoInterfaceObject] interface GlobalEventHandlers { attribute EventHandler onabort; attribute EventHandler onblur; attribute EventHandler oncancel; attribute EventHandler oncanplay; attribute EventHandler oncanplaythrough; attribute EventHandler onchange; attribute EventHandler onclick; attribute EventHandler onclose; attribute EventHandler oncontextmenu; attribute EventHandler oncuechange; attribute EventHandler ondblclick; attribute EventHandler ondrag; attribute EventHandler ondragend; attribute EventHandler ondragenter; attribute EventHandler ondragexit; attribute EventHandler ondragleave; attribute EventHandler ondragover; attribute EventHandler ondragstart; attribute EventHandler ondrop; attribute EventHandler ondurationchange; attribute EventHandler onemptied; attribute EventHandler onended; attribute OnErrorEventHandler onerror; attribute EventHandler onfocus; attribute EventHandler oninput; attribute EventHandler oninvalid; attribute EventHandler onkeydown; attribute EventHandler onkeypress; attribute EventHandler onkeyup; attribute EventHandler onload; attribute EventHandler onloadeddata; attribute EventHandler onloadedmetadata; attribute EventHandler onloadstart; attribute EventHandler onmousedown; [LenientThis] attribute EventHandler onmouseenter; [LenientThis] attribute EventHandler onmouseleave; attribute EventHandler onmousemove; attribute EventHandler onmouseout; attribute EventHandler onmouseover; attribute EventHandler onmouseup; attribute EventHandler onwheel; attribute EventHandler onpause; attribute EventHandler onplay; attribute EventHandler onplaying; attribute EventHandler onprogress; attribute EventHandler onratechange; attribute EventHandler onreset; attribute EventHandler onresize; attribute EventHandler onscroll; attribute EventHandler onseeked; attribute EventHandler onseeking; attribute EventHandler onselect; attribute EventHandler onshow; attribute EventHandler onstalled; attribute EventHandler onsubmit; attribute EventHandler onsuspend; attribute EventHandler ontimeupdate; attribute EventHandler ontoggle; attribute EventHandler onvolumechange; attribute EventHandler onwaiting; };
[NoInterfaceObject] interface WindowEventHandlers { attribute EventHandler onafterprint; attribute EventHandler onbeforeprint; attribute OnBeforeUnloadEventHandler onbeforeunload; attribute EventHandler onhashchange; attribute EventHandler onlanguagechange; attribute EventHandler onmessage; attribute EventHandler onoffline; attribute EventHandler ononline; attribute EventHandler onpagehide; attribute EventHandler onpageshow; attribute EventHandler onrejectionhandled; attribute EventHandler onpopstate; attribute EventHandler onstorage; attribute EventHandler onunhandledrejection; attribute EventHandler onunload; };
[NoInterfaceObject] interface DocumentAndElementEventHandlers { attribute EventHandler oncopy; attribute EventHandler oncut; attribute EventHandler onpaste; };
7.1.5.3. Event firing
Certain operations and methods are defined as firing events on elements. For example, the click()
method on the HTMLElement
interface is defined as firing a click
event on the element. [UIEVENTS]
Firing a simple event named e means that a trusted event with the name e, which does not
bubble (except where otherwise stated) and is not cancelable (except where otherwise stated), and
which uses the Event
interface, must be created and dispatched at the given target.
Firing a synthetic mouse event named e means that an event with the name e, which is trusted (except where otherwise
stated), does not bubble (except where otherwise stated), is not cancelable (except where
otherwise stated), and which uses the MouseEvent
interface, must be created and dispatched at
the given target. The event object must have its screenX
, screenY
,
{{MouseEvent/clientX}, clientY
, and button
attributes initialized to
0, its ctrlKey
, shiftKey
, altKey
, and metaKey
attributes initialized according to the current state of the key input
device, if any (false for any keys that are not available), its detail
attribute
initialized to 1, its relatedTarget
attribute initialized to null (except where
otherwise stated), and its view
attribute initialized to the Window
object of
the Document
object of the given target node, if any, or else null. The getModifierState()
method on the object must return values appropriately describing
the state of the key input device at the time the event is created.
Firing a click
event means firing a synthetic mouse event named click
, which bubbles and is cancelable.
The default action of these events is to do nothing except where otherwise stated.
7.1.5.4. Events and the Window
object
When an event is dispatched at a DOM node in a Document
in a browsing
context, if the event is not a load
event, the user agent
must act as if, for the purposes of event dispatching,
the Window
object is the parent of the Document
object. [DOM]
7.2. Base64 utility methods
The atob()
and btoa()
methods allow authors to transform content to and from
the base64 encoding.
[NoInterfaceObject, Exposed=(Window, Worker)] interface WindowBase64 { DOMString btoa(DOMString btoa); DOMString atob(DOMString atob); }; Window implements WindowBase64; WorkerGlobalScope implements WindowBase64;
In these APIs, for mnemonic purposes, the "b" can be considered to stand for "binary", and the "a" for "ASCII". In practice, though, for primarily historical reasons, both the input and output of these functions are Unicode strings.
- result = window .
btoa
( data ) -
Takes the input data, in the form of a Unicode string containing only characters in the range U+0000 to U+00FF, each representing a binary byte with values 0x00 to 0xFF respectively, and converts it to its base64 representation, which it returns.
Throws an
InvalidCharacterError
exception if the input string contains any out-of-range characters. - result = window .
atob
( data ) -
Takes the input data, in the form of a Unicode string containing base64-encoded binary data, decodes it, and returns a string consisting of characters in the range U+0000 to U+00FF, each representing a binary byte with values 0x00 to 0xFF respectively, corresponding to that binary data.
Throws an
InvalidCharacterError
exception if the input string is not valid base64 data.
The btoa()
method must throw an InvalidCharacterError
exception if the method’s first argument contains any character
whose code point is greater than U+00FF. Otherwise, the user agent must convert that argument to a
sequence of octets whose nth octet is the eight-bit representation of the code
point of the nth character of the argument, and then must apply the base64
algorithm to that sequence of octets, and return the result. [RFC4648]
The atob()
method must run the following
steps to parse the string passed in the method’s first argument:
- Let input be the string being parsed.
- Let position be a pointer into input, initially pointing at the start of the string.
- Remove all space characters from input.
- If the length of input divides by 4 leaving no remainder, then: if input ends with one or two U+003D EQUALS SIGN (=) characters, remove them from input.
- If the length of input divides by 4 leaving a remainder of 1, throw an
InvalidCharacterError
exception and abort these steps. -
If input contains a character that is not in the following list of characters and character ranges, throw an
InvalidCharacterError
exception and abort these steps:- U+002B PLUS SIGN (+)
- U+002F SOLIDUS (/)
- Alphanumeric ASCII characters
- Let output be a string, initially empty.
- Let buffer be a buffer that can have bits appended to it, initially empty.
-
While position does not point past the end of input, run these substeps:
-
Find the character pointed to by position in the first column of the following table. Let n be the number given in the second cell of the same row.
Character Number A 0 B 1 C 2 D 3 E 4 F 5 G 6 H 7 I 8 J 9 K 10 L 11 M 12 N 13 O 14 P 15 Q 16 R 17 S 18 T 19 U 20 V 21 W 22 X 23 Y 24 Z 25 a 26 b 27 c 28 d 29 e 30 f 31 g 32 h 33 i 34 j 35 k 36 l 37 m 38 n 39 o 40 p 41 q 42 r 43 s 44 t 45 u 46 v 47 w 48 x 49 y 50 z 51 0 52 1 53 2 54 3 55 4 56 5 57 6 58 7 59 8 60 9 61 + 62 / 63 - Append to buffer the six bits corresponding to number, most significant bit first.
- If buffer has accumulated 24 bits, interpret them as three 8-bit big-endian numbers. Append the three characters with code points equal to those numbers to output, in the same order, and then empty buffer.
- Advance position by one character.
-
-
If buffer is not empty, it contains either 12 or 18 bits. If it contains 12 bits, discard the last four and interpret the remaining eight as an 8-bit big-endian number. If it contains 18 bits, discard the last two and interpret the remaining 16 as two 8-bit big-endian numbers. Append the one or two characters with code points equal to those one or two numbers to output, in the same order.
The discarded bits mean that, for instance,
atob("YQ")
andatob("YR")
both return "a
". - Return output.
7.3. Dynamic markup insertion
APIs for dynamically inserting markup into the document interact with the parser, and thus their behavior varies depending on whether they are used with HTML documents (and the HTML parser) or XHTML in XML documents (and the XML parser).
7.3.1. Opening the input stream
The open()
method comes in several variants with different numbers of arguments.
- document = document .
open
( [ type [, replace ] ] ) -
Causes the
Document
to be replaced in-place, as if it was a newDocument
object, but reusing the previous object, which is then returned.If the type argument is omitted or has the value "
text/html
", then the resultingDocument
has an HTML parser associated with it, which can be given data to parse usingdocument.write()
. Otherwise, all content passed todocument.write()
will be parsed as plain text.If the replace argument is present and has the value "
replace
", the existing entries in the session history for theDocument
object are removed.The method has no effect if the
Document
is still being parsed.Throws an "
InvalidStateError
"DOMException
if theDocument
is an XML document. - window = document .
open
( url, name, features [, replace ] ) - Works like the
window.open()
method.
Document
objects have an ignore-opens-during-unload counter, which is used to
prevent scripts from invoking the document.open()
method (directly or
indirectly) while the document is being unloaded. Initially, the counter must be set to
zero.
When called with two arguments (or fewer), the document.open()
method must act
as follows:
-
If the
Document
object is an XML document, then throw an "InvalidStateError
"DOMException
and abort these steps. -
If the
Document
object is not an active document, then abort these steps. -
If the origin of the
Document
is not equal to the origin of the responsible document specified by the entry settings object, throw a "SecurityError
"DOMException
and abort these steps. -
Let type be the value of the first argument.
-
If the second argument is an ASCII case-insensitive match for the value "
replace
", then let replace be true.Otherwise, if the browsing context’s session history contains only one
Document
, and that was theabout:blank
Document
created when the browsing context was created, and thatDocument
has never had the unload a document algorithm invoked on it (e.g., by a previous call todocument.open()
), then let replace be true.Otherwise, let replace be false.
-
If the
Document
has an active parser whose script nesting level is greater than zero, then the method does nothing. Abort these steps and return theDocument
object on which the method was invoked.This basically causes
document.open()
to be ignored when it’s called in an inline script found during parsing, while still letting it have an effect when called from a non-parser task such as a timer callback or event handler. -
Similarly, if the
Document
's ignore-opens-during-unload counter is greater than zero, then the method does nothing. Abort these steps and return theDocument
object on which the method was invoked.This basically causes
document.open()
to be ignored when it’s called from abeforeunload
pagehide
, orunload
event handler while theDocument
is being unloaded. -
Set the
Document
's salvageable state to false. -
Prompt to unload the
Document
object. If the user refused to allow the document to be unloaded, then abort these steps and return theDocument
object on which the method was invoked. -
Unload the
Document
object, with the recycle parameter set to true. -
Unregister all event listeners registered on the
Document
node and its descendants. -
Remove any tasks associated with the
Document
in any task source. -
Remove all child nodes of the document, without firing any mutation events.
-
Call the JavaScript InitializeHostDefinedRealm() abstract operation with the following customizations:
-
For the global object, create a new
Window
object window. -
For the global this value, use the current browsing context’s associated
WindowProxy
. -
Let realm execution context be the created JavaScript execution context.
-
-
Set window’s associated
Document
to theDocument
. -
Set up a browsing context environment settings object with realm execution context.
-
Replace the
Document
's singleton objects with new instances of those objects, created in window’s Realm. (This includes in particular theHistory
,ApplicationCache
andNavigator
objects, the variousBarProp
objects, the twoStorage
objects, the variousHTMLCollection
objects, and objects defined by other specifications, likeSelection
. It also includes all the Web IDL prototypes in the JavaScript binding, including theDocument
object’s prototype.) -
Change the document’s character encoding to UTF-8.
-
If the
Document
is ready for post-load tasks, then set theDocument
object’s reload override flag and set theDocument
's reload override buffer to the empty string. -
Set the
Document
's salvageable state back to true. -
Change the document’s URL to the URL of the responsible document specified by the entry settings object.
-
If the
Document
's iframe load in progress flag is set, set theDocument
's mute iframe load flag. -
Create a new HTML parser and associate it with the document. This is a script-created parser (meaning that it can be closed by the
document.open()
anddocument.close()
methods, and that the tokenizer will wait for an explicit call todocument.close()
before emitting an end-of-file token). The encoding confidence is irrelevant. -
Set the current document readiness of the document to "
loading
". -
If type is an ASCII case-insensitive match for the string "
replace
", then, for historical reasons, set it to the string "text/html
".Otherwise:
If the type string contains a U+003B SEMICOLON character (;), remove the first such character and all characters from it up to the end of the string.
Strip leading and trailing whitespace from type.
-
If type is not now an ASCII case-insensitive match for the string "
text/html
", then act as if the tokenizer had emitted a start tag token with the tag name "pre" followed by a single U+000A LINE FEED (LF) character, then switch the HTML parser’s tokenizer to the §8.2.4.7 PLAINTEXT state. -
Remove all the entries in the browsing context’s session history after the current entry. If the current entry is the last entry in the session history, then no entries are removed.
This doesn’t necessarily have to affect the user agent’s user interface.
-
Remove any tasks queued by the history traversal task source that are associated with any
Document
objects in the top-level browsing context’s document family. -
Remove any earlier entries that share the same
Document
. -
If replace is false, then add a new entry, just before the last entry, and associate with the new entry the text that was parsed by the previous parser associated with the
Document
object, as well as the state of the document at the start of these steps. This allows the user to step backwards in the session history to see the page before it was blown away by thedocument.open()
call. This new entry does not have aDocument
object, so a new one will be created if the session history is traversed to that entry. -
Set the
Document
's fired unload flag to false. (It could have been set to true during the unload step above.) -
Finally, set the insertion point to point at just before the end of the input stream (which at this point will be empty).
-
Return the
Document
on which the method was invoked.
The document.open()
method does not affect whether a Document
is ready for post-load tasks or completely loaded.
When called with four arguments, the open()
method on the Document
object must
call the open()
method on the Window
object of the Document
object, with the
same arguments as the original call to the open()
method, and return whatever that
method returned. If the Document
object has no Window
object, then the method must throw
an "InvalidAccessError
" DOMException
.
7.3.2. Closing the input stream
- document .
close()
-
Closes the input stream that was opened by the
document.open()
method.Throws an
InvalidStateError
exception if theDocument
is an XML document.
The close()
method must run the following
steps:
- If the
Document
object is not flagged as an HTML document, throw anInvalidStateError
exception and abort these steps. - If there is no script-created parser associated with the document, then abort these steps.
- Insert an explicit "EOF" character at the end of the parser’s input stream.
- If there is a pending parsing-blocking script, then abort these steps.
- Run the tokenizer, processing resulting tokens as they are emitted, and stopping when the tokenizer reaches the explicit "EOF" character or spins the event loop.
7.3.3. document.write()
- document .
write
(text...) -
In general, adds the given string(s) to the
Document
’s input stream.This method has very idiosyncratic behavior. In some cases, this method can affect the state of the HTML parser while the parser is running, resulting in a DOM that does not correspond to the source of the document (e.g., if the string written is the string "
<plaintext>
" or "<!--
"). In other cases, the call can clear the current page first, as ifdocument.open()
had been called. In yet more cases, the method is simply ignored, or throws an exception. To make matters worse, the exact behavior of this method can in some cases be dependent on network latency, which can lead to failures that are very hard to debug. For all these reasons, use of this method is strongly discouraged.This method throws an
InvalidStateError
exception when invoked on XML documents.
Document
objects have an ignore-destructive-writes counter, which is
used in conjunction with the processing of script
elements to prevent external
scripts from being able to use document.write()
to blow
away the document by implicitly calling document.open()
.
Initially, the counter must be set to zero.
The document.write(...)
method must act as
follows:
-
If the method was invoked on an XML document, throw an
InvalidStateError
exception and abort these steps. - If the
Document
object is not an active document, then abort these steps. -
If the insertion point is undefined and either the
Document
’s ignore-opens-during-unload counter is greater than zero or theDocument
’s ignore-destructive-writes counter is greater than zero, abort these steps. -
If the insertion point is undefined, call the
open()
method on thedocument
object (with no arguments). If the user refused to allow the document to be unloaded, then abort these steps. Otherwise, the insertion point will point at just before the end of the (empty) input stream. -
Insert the string consisting of the concatenation of all the arguments to the method into the input stream just before the insertion point.
-
If the
Document
object’s reload override flag is set, then append the string consisting of the concatenation of all the arguments to the method to theDocument
’s reload override buffer. -
If there is no pending parsing-blocking script, have the HTML parser process the characters that were inserted, one at a time, processing resulting tokens as they are emitted, and stopping when the tokenizer reaches the insertion point or when the processing of the tokenizer is aborted by the tree construction stage (this can happen if a
script
end tag token is emitted by the tokenizer).If the
document.write()
method was called from script executing inline (i.e., executing because the parser parsed a set ofscript
tags), then this is a reentrant invocation of the parser. -
Finally, return from the method.
7.3.4. document.writeln()
- document .
writeln
(text...) -
Adds the given string(s) to the
Document
’s input stream, followed by a newline character. If necessary, calls theopen()
method implicitly first.This method throws an
InvalidStateError
exception when invoked on XML documents.
The document.writeln(...)
method, when
invoked, must act as if the document.write()
method had
been invoked with the same argument(s), plus an extra argument consisting of a string containing a
single line feed character (U+000A).
7.4. Timers
The setTimeout()
and setInterval()
methods allow authors to schedule timer-based callbacks.
[NoInterfaceObject, Exposed=(Window,Worker)] interface WindowTimers { long setTimeout((Function or DOMString) handler, optional long timeout = 0, any... arguments); void clearTimeout(optional long handle = 0); long setInterval((Function or DOMString) handler, optional long timeout = 0, any... arguments); void clearInterval(optional long handle = 0); }; Window implements WindowTimers; WorkerGlobalScope implements WindowTimers;
- handle = window .
setTimeout
( handler [, timeout [, arguments... ] ] ) -
Schedules a timeout to run handler after timeout milliseconds. Any arguments are passed straight through to the handler.
- handle = window .
setTimeout
( code [, timeout ] ) -
Schedules a timeout to compile and run code after timeout milliseconds.
- window .
clearTimeout
( handle ) -
Cancels the timeout set with
setTimeout()
orsetInterval()
identified by handle. - handle = window .
setInterval
( handler [, timeout [, arguments... ] ] ) -
Schedules a timeout to run handler every timeout milliseconds. Any arguments are passed straight through to the handler.
- handle = window .
setInterval
( code [, timeout ] ) -
Schedules a timeout to compile and run code every timeout milliseconds.
- window .
clearInterval
( handle ) -
Cancels the timeout set with
setInterval()
orsetTimeout()
identified by handle.
Timers can be nested; after five such nested timers, however, the interval is forced to be at least four milliseconds.
This API does not guarantee that timers will run exactly on schedule. Delays due to CPU load, other tasks, etc, are to be expected.
Objects that implement the WindowTimers
interface have a list of active
timers. Each entry in this lists is identified by a number, which must be unique within the
list for the lifetime of the object that implements the WindowTimers
interface.
The setTimeout()
method must return
the value returned by the timer initialization steps, passing them the method’s
arguments, the object on which the method for which the algorithm is running is implemented (a Window
or WorkerGlobalScope
object) as the method
context, and the repeat flag set to false.
The setInterval()
method must
return the value returned by the timer initialization steps, passing them the
method’s arguments, the object on which the method for which the algorithm is running is
implemented (a Window
or WorkerGlobalScope
object) as the method context, and the repeat flag set to true.
The clearTimeout()
and clearInterval()
methods must clear the
entry identified as handle from the list of active timers of the WindowTimers
object on which the method was invoked, if any, where handle is the argument passed to the method. (If handle does
not identify an entry in the list of active timers of the WindowTimers
object on which the method was invoked, the method does nothing.)
Because clearTimeout()
and clearInterval()
clear entries from the same
list, either method can be used to clear timers created by setTimeout()
or setInterval()
.
The timer initialization steps, which are invoked with some method arguments, a method context, a repeat flag which can be true or false, and optionally (and only if the repeat flag is true) a previous handle, are as follows:
- Let method context proxy be method context if that
is a
WorkerGlobalScope
object, or else theWindowProxy
that corresponds to method context. - If previous handle was provided, let handle be previous handle; otherwise, let handle be a user-agent-defined integer that is greater than zero that will identify the timeout to be set by this call in the list of active timers.
- If previous handle was not provided, add an entry to the list of active timers for handle.
- Let callerRealm be the current Realm Record, and calleeRealm be method context’s JavaScript realm.
-
Let task be a task that runs the following substeps:
- If the entry for handle in the list of active timers has been cleared, then abort this task’s substeps.
-
Run the appropriate set of steps from the following list:
- If the first method argument is a
Function
-
Invoke the
Function
. Use the third and subsequent method arguments (if any) as the arguments for invoking theFunction
. Use method context proxy as the Callback this value. [ECMA-262] - Otherwise
-
- Perform HostEnsureCanCompileStrings(callerRealm, calleeRealm). If this throws an exception, report the exception.
- Let script source be the first method argument.
- Let script language be JavaScript.
- Let settings object be method context’s environment settings object.
- Create a script using script source as the script source, the URL where script source can be found, scripting language as the scripting language, and settings object as the environment settings object.
- If the first method argument is a
- If the repeat flag is true, then call timer initialization steps again, passing them the same method arguments, the same method context, with the repeat flag still set to true, and with the previous handle set to handler.
- Let timeout be the second method argument.
- If the currently running task is a task that was created by this algorithm, then let nesting level be the task’s timer nesting level. Otherwise, let nesting level be zero.
- If nesting level is greater than 5, and timeout is less than 4, then increase timeout to 4.
- Increment nesting level by one.
- Let task’s timer nesting level be nesting level.
- Return handle, and then continue running this algorithm in parallel.
-
If method context is a
Window
object, wait until theDocument
associated with method context has been fully active for a further timeout milliseconds (not necessarily consecutively).Otherwise, method context is a
WorkerGlobalScope
object; wait until timeout milliseconds have passed with the worker not suspended (not necessarily consecutively). -
Wait until any invocations of this algorithm that had the same method context, that started before this one, and whose timeout is equal to or less than this one’s, have completed.
Argument conversion as defined by Web IDL (for example, invoking
toString()
methods on objects passed as the first argument) happens in the algorithms defined in Web IDL, before this algorithm is invoked. -
Optionally, wait a further user-agent defined length of time.
This is intended to allow user agents to pad timeouts as needed to optimize the power usage of the device. For example, some processors have a low-power mode where the granularity of timers is reduced; on such platforms, user agents can slow timers down to fit this schedule instead of requiring the processor to use the more accurate mode with its associated higher power usage.
-
Once the task has been processed, if the repeat flag is false, it is safe to remove the entry for handle from the list of active timers (there is no way for the entry’s existence to be detected past this point, so it does not technically matter one way or the other).
The task source for these tasks is the timer task source.
function doExpensiveWork() {var done = false; // ... // this part of the function takes up to five milliseconds // set done to true if we’re done // ... return done; } function rescheduleWork() { var handle = setTimeout(rescheduleWork, 0); // preschedule next iteration if (doExpensiveWork()) clearTimeout(handle); // clear the timeout if we don’t need it } function scheduleWork() { setTimeout(rescheduleWork, 0); } scheduleWork(); // queues a task to do lots of work
7.5. User prompts
7.5.1. Simple dialogs
- window .
alert
(message) -
Displays a modal alert with the given message, and waits for the user to dismiss it.
- result = window .
confirm
(message) -
Displays a modal OK/Cancel prompt with the given message, waits for the user to dismiss it, and returns true if the user clicks OK and false if the user clicks Cancel.
- result = window .
prompt
(message [, default] ) -
Displays a modal text field prompt with the given message, waits for the user to dismiss it, and returns the value that the user entered. If the user cancels the prompt, then returns null instead. If the second argument is present, then the given value is used as a default.
Logic that depends on tasks or microtasks, such as media elements loading their media data, are stalled when these methods are invoked.
To optionally truncate a simple dialog string s, return either s itself or some string derived from s that is shorter. User agents should not provide UI for displaying the elided portion of s, as this makes it too easy for abusers to create dialogs of the form "Important security alert! Click 'Show More' for full details!".
For example, a user agent might want to only display the first 100 characters of a message. Or, a user agent might replace the middle of the string with "…". These types of modifications can be useful in limiting the abuse potential of unnaturally large, trustworthy-looking system dialogs.
The alert(message)
method, when invoked, must run the following steps:
- If the event loop’s termination nesting level is non-zero, optionally abort these steps.
- If the active sandboxing flag set of the active document of the responsible browsing context specified by the incumbent settings object has the sandboxed modals flag set, then abort these steps.
- Optionally, abort these steps. (For example, the user agent might give the user the option to ignore all alerts, and would thus abort at this step whenever the method was invoked.)
- If the method was invoked with no arguments, then let message be the empty string; otherwise, let message be the method’s first argument.
- Show the given message to the user.
- Optionally, pause while waiting for the user to acknowledge the message.
The confirm(message)
method, when invoked, must run the following steps:
- If the event loop’s termination nesting level is non-zero, optionally abort these steps, returning false.
- If the active sandboxing flag set of the active document of the responsible browsing context specified by the incumbent settings object has the sandboxed modals flag set, then return false and abort these steps.
- Optionally, return false and abort these steps. (For example, the user agent might give the user the option to ignore all prompts, and would thus abort at this step whenever the method was invoked.)
- Set message to the result of optionally truncating message.
- Show message to the user, and ask the user to respond with a positive or negative response.
- Pause until the user responds either positively or negatively.
- If the user responded positively, return true; otherwise, the user responded negatively: return false.
The prompt(message, default)
method, when invoked, must run the following steps:
- If the event loop’s termination nesting level is non-zero, optionally abort these steps, returning null.
- If the active sandboxing flag set of the active document of the responsible browsing context specified by the incumbent settings object has the sandboxed modals flag set, then return null and abort these steps.
- Optionally, return null and abort these steps. (For example, the user agent might give the user the option to ignore all prompts, and would thus abort at this step whenever the method was invoked.)
- Set message to the result of optionally truncating message.
- Set default to the result of optionally truncating default.
- Show message to the user, and ask the user to either respond with a string value or abort. The response must be defaulted to the value given by default.
- Pause while waiting for the user’s response.
- If the user aborts, then return null; otherwise, return the string that the user responded with.
7.5.2. Printing
- window .
print()
-
Prompts the user to print the page.
When the print()
method is invoked, if the Document
is ready for post-load tasks, then the user agent must
run the printing steps in parallel. Otherwise, the user agent must only set the print when loaded flag on the Document
.
User agents should also run the printing steps whenever the user asks for the opportunity to obtain a physical form (e.g., printed copy), or the representation of a physical form (e.g., PDF copy), of a document.
The printing steps are as follows:
-
The user agent may display a message to the user or abort these steps (or both).
For instance, a kiosk browser could silently ignore any invocations of the
print()
method.For instance, a browser on a mobile device could detect that there are no printers in the vicinity and display a message saying so before continuing to offer a "save to PDF" option.
-
If the active sandboxing flag set of the active document of the responsible browsing context specified by the incumbent settings object has the sandboxed modals flag set, then abort these steps.
If the printing dialog is blocked by a
Document
’s sandbox, then neither thebeforeprint
norafterprint
events will be fired. -
The user agent must fire a simple event named
beforeprint
at theWindow
object of theDocument
that is being printed, as well as any nested browsing contexts in it.The
beforeprint
event can be used to annotate the printed copy, for instance adding the time at which the document was printed. -
The user agent should offer the user the opportunity to obtain a physical form (or the representation of a physical form) of the document. The user agent may wait for the user to either accept or decline before returning; if so, the user agent must pause while the method is waiting. Even if the user agent doesn’t wait at this point, the user agent must use the state of the relevant documents as they are at this point in the algorithm if and when it eventually creates the alternate form.
-
The user agent must fire a simple event named
afterprint
at theWindow
object of theDocument
that is being printed, as well as any nested browsing contexts in it.The
afterprint
event can be used to revert annotations added in the earlier event, as well as showing post-printing UI. For instance, if a page is walking the user through the steps of applying for a home loan, the script could automatically advance to the next step after having printed a form or other.
7.5.3. Dialogs implemented using separate documents with showModalDialog()
This feature is in the process of being removed from the Web platform. (This
is a long process that takes many years.) Using the showModalDialog()
API at this time is highly discouraged.
The showModalDialog(url, argument)
method, when invoked, must cause the user agent to run the following steps:
-
Parse url relative to the API base URL specified by the entry settings object.
If this fails, then throw a "
SyntaxError
"DOMException
and abort these steps. - If the event loop’s termination nesting level is non-zero, optionally abort these steps, returning the empty string.
-
If the user agent is configured such that this invocation of
showModalDialog()
is somehow disabled, then return the empty string and abort these steps.User agents are expected to disable this method in certain cases to avoid user annoyance (e.g., as part of their popup blocker feature). For instance, a user agent could require that a site be safelisted before enabling this method, or the user agent could be configured to only allow one modal dialog at a time.
-
If the active sandboxing flag set of the active document of the responsible browsing context specified by the incumbent settings object has either the sandboxed auxiliary navigation browsing context flag or sandboxed modals flag set, then return the empty string and abort these steps.
-
Let incumbent origin be the origin specified by the incumbent settings object at the time the
showModalDialog()
method was called. -
Let the list of background browsing contexts be a list of all the browsing contexts that:
- are part of the same unit of related browsing contexts as the browsing context
of the
Window
object on which theshowModalDialog()
method was called, and that - have an active document whose origin is the same as incumbent origin,
...as well as any browsing contexts that are nested inside any of the browsing contexts matching those conditions.
- are part of the same unit of related browsing contexts as the browsing context
of the
-
Disable the user interface for all the browsing contexts in the list of background browsing contexts. This should prevent the user from navigating those browsing contexts, causing events to be sent to those browsing context, or editing any content in those browsing contexts. However, it does not prevent those browsing contexts from receiving events from sources other than the user, from running scripts, from running animations, and so forth.
-
Create a new auxiliary browsing context, with the opener browsing context being the browsing context of the
Window
object on which theshowModalDialog()
method was called. The new auxiliary browsing context has no name.This browsing context’s
Document
s'Window
objects all implement theWindowModal
interface. -
Set all the flags in the new browsing context’s popup sandboxing flag set that are set in the active sandboxing flag set of the active document of the responsible browsing context specified by the incumbent settings object. The responsible browsing context specified by the incumbent settings object must be set as the new browsing context’s one permitted sandboxed navigator.
-
Let the dialog arguments of the new browsing context be set to the value of argument, or the undefined value if the argument was omitted.
-
Let the dialog arguments' origin be incumbent origin.
-
Let the return value of the new browsing context be the undefined value.
-
Let the return value origin be incumbent origin.
-
Navigate the new browsing context to the absolute URL that resulted from parsing url earlier, with replacement enabled, and with the responsible browsing context specified by the incumbent settings object as the source browsing context.
-
Spin the event loop until the new browsing context is closed. The user agent must allow the user to indicate that the browsing context is to be closed.
-
Reenable the user interface for all the browsing contexts in the list of background browsing contexts.
-
If the auxiliary browsing context’s return value origin at the time the browsing context was closed was the same as incumbent origin, then let return value be the auxiliary browsing context’s return value as it stood when the browsing context was closed.
Otherwise, let return value be undefined.
-
Return return value.
The Window
objects of Document
s hosted by browsing contexts created by the above algorithm must also implement the WindowModal
interface.
When this happens, the members of the WindowModal
interface, in
JavaScript environments, appear to actually be part of the Window
interface (e.g.,
they are on the same prototype chain as the window.alert()
method).
[NoInterfaceObject] interface WindowModal { readonly attribute any dialogArguments; attribute any returnValue; };
- window .
dialogArguments
-
Returns the argument argument that was passed to the
showModalDialog()
method. - window .
returnValue
[ = value ] -
Returns the current return value for the window.
Can be set, to change the value that will be returned by the
showModalDialog()
method.
Such browsing contexts have associated dialog arguments, which are stored along with
the dialog arguments' origin. These values are set by the showModalDialog()
method in the algorithm above, when the
browsing context is created, based on the arguments provided to the method.
The dialogArguments
IDL
attribute, on getting, must check whether its browsing context’s active document’s origin is the same origin-domain as the dialog arguments' origin. If it is,
then the browsing context’s dialog arguments must be returned unchanged. Otherwise, the
IDL attribute must return undefined.
These browsing contexts also have an associated return value and return value origin. As with the previous two values, these values are set by the showModalDialog()
method in the algorithm above, when the
browsing context is created.
The returnValue
IDL attribute, on
getting, must check whether its browsing context’s active document’s origin is the same origin-domain as the current return value origin. If it
is, then the browsing context’s return value must be returned unchanged. Otherwise,
the IDL attribute must return undefined. On setting, the attribute must set the return value to the given new value, and the return value origin to the browsing context’s active document’s origin.
The window.close()
method can be used to
close the browsing context.
7.6. System state and capabilities
7.6.1. The Navigator
object
The navigator
attribute of the Window
interface must return an instance of the Navigator
interface,
which represents the identity and state of the user agent (the client), and allows Web pages to
register themselves as potential protocol and content handlers:
interface Navigator { // objects implementing this interface also implement the interfaces given below }; Navigator implements NavigatorID; Navigator implements NavigatorLanguage; Navigator implements NavigatorOnLine; Navigator implements NavigatorContentUtils; Navigator implements NavigatorCookies; Navigator implements NavigatorPlugins;
These interfaces are defined separately so that other specifications can re-use parts of the Navigator
interface.
7.6.1.1. Client identification
[NoInterfaceObject, Exposed=(Window, Worker)] interface NavigatorID { [Exposed=Window] readonly attribute DOMString appCodeName; // constant "Mozilla" readonly attribute DOMString appName; // constant "Netscape" readonly attribute DOMString appVersion; readonly attribute DOMString platform; [Exposed=Window]readonly attribute DOMString product; // constant "Gecko" readonly attribute DOMString userAgent; };
In certain cases, despite the best efforts of the entire industry, Web browsers have bugs and limitations that Web authors are forced to work around.
This section defines a collection of attributes that can be used to determine, from script, the kind of user agent in use, in order to work around these issues.
Client detection should always be limited to detecting known current versions; future versions and unknown versions should always be assumed to be fully compliant.
- window .
navigator
.appCodeName
- Returns the string "
Mozilla
". - window .
navigator
.appName
- Returns the string "
Netscape
". - window .
navigator
.appVersion
- Returns the version of the browser.
- window .
navigator
.platform
- Returns the name of the platform.
- window .
navigator
.product
- Returns the string "
Gecko
". - window .
navigator
.taintEnabled
() - Returns either the string "
20030107
", or the string "20100101
". - window .
navigator
.userAgent
- Returns the complete User-Agent header.
appCodeName
, of type DOMString, readonly- Must return the string "
Mozilla
". appName
, of type DOMString, readonly- Must return the string "
Netscape
". appVersion
, of type DOMString, readonly- Must return either the string "
4.0
" or a string representing the version of the browser in detail, e.g., "1.0 (VMS; en-US) Mellblomenator/9000
". platform
, of type DOMString, readonly- Must return either the empty string or a string representing the platform on which the
browser is executing, e.g., "
MacIntel
", "Win32
", "FreeBSD i386
", "WebTV OS
". product
, of type DOMString, readonly- Must return the string "
Gecko
". taintEnabled()
- Must return false.
userAgent
, of type DOMString, readonly- Must return the string used for the value of the "
User-Agent
" header in HTTP requests, or the empty string if no such header is ever sent.
Any information in this API that varies from user to user can be used to profile the user. In fact, if enough such information is available, a user can actually be uniquely identified. For this reason, user agent implementors are strongly urged to include as little information in this API as possible.
7.6.1.2. Language preferences
[NoInterfaceObject, Exposed=(Window, Worker)] interface NavigatorLanguage { readonly attribute DOMString? language; readonly attribute DOMString[] languages; };
- window .
navigator
.language
- Returns a language tag representing the user’s preferred language.
- window .
navigator
.languages
- Returns an array of language tags representing the user’s preferred languages, with the most preferred language first.
The most preferred language is the one returned by
navigator.language
.
A languagechange
event is fired at the Window
or WorkerGlobalScope
object when the user agent’s understanding
of what the user’s preferred languages are changes.
language
, of type DOMString, readonly, nullable- Must return a valid BCP 47 language tag representing either a plausible language or the user’s most preferred language. [BCP47]
languages
, of type DOMString[], readonly-
Must return a read only array of valid BCP 47 language tags representing either one or more plausible languages, or the user’s preferred languages, ordered by preference with the most preferred language first. The same object must be returned until the user agent needs to return different values, or values in a different order. [BCP47]
Whenever the user agent needs to make the
navigator.languages
attribute of aWindow
orWorkerGlobalScope
object return a new set of language tags, the user agent must queue a task to fire a simple event namedlanguagechange
at theWindow
orWorkerGlobalScope
object and wait until that task begins to be executed before actually returning a new value.The task source for this task is the DOM manipulation task source.
To determine a plausible language, the user agent should bear in mind the following:
- Any information in this API that varies from user to user can be used to profile or identify the user.
- If the user is not using a service that obfuscates the user’s point of origin (e.g., the Tor anonymity network), then the value that is least likely to distinguish the user from other users with similar origins (e.g., from the same IP address block) is the language used by the majority of such users. [TOR]
- If the user is using an anonymizing service, then the value "
en-US
" is suggested; if all users of the service use that same value, that reduces the possibility of distinguishing the users from each other.
To avoid introducing any more fingerprinting vectors, user agents should use the same list for
the APIs defined in this function as for the HTTP Accept-Language
header.
7.6.1.3. Custom scheme handler: the registerProtocolHandler()
method
[NoInterfaceObject] interface NavigatorContentUtils { // content handler registration void registerProtocolHandler(DOMString scheme, DOMString url, DOMString title); void unregisterProtocolHandler(DOMString scheme, DOMString url); };
The registerProtocolHandler()
method
allows Web sites to register themselves as possible handlers for particular schemes. For example,
an online telephone messaging service could register itself as a handler of the sms:
scheme, so that if the user clicks on such a link, he is given the
opportunity to use that Web site. [RFC5724]
- window .
navigator
.registerProtocolHandler
(scheme, url, title) -
Registers a handler for the given scheme, at the given URL, with the given title.
The string "
%s
" in the URL is used as a placeholder for where to put the URL of the content to be handled.Throws a "
SecurityError
"DOMException
if the user agent blocks the registration (this might happen if trying to register as a handler for "http", for instance).Throws a "
SyntaxError
"DOMException
if the "%s
" string is missing in the URL.
User agents may, within the constraints described in this section, do whatever they like when the method is called. A user agent could, for instance, prompt the user and offer the user the opportunity to add the site to a shortlist of handlers, or make the handler his default, or cancel the request. User agents could provide such a UI through modal UI or through a non-modal transient notification interface. user agents could also simply silently collect the information, providing it only when relevant to the user.
User agents should keep track of which sites have registered handlers (even if the user has declined such registrations) so that the user is not repeatedly prompted with the same request.
The arguments to the method have the following meanings and corresponding implementation requirements. The requirements that involve throwing exceptions must be processed in the order given below, stopping at the first exception thrown. (So the exceptions for the first argument take precedence over the exceptions for the second argument.)
- scheme (
registerProtocolHandler()
) -
A scheme, such as "
mailto
" or "web+auth
". The scheme must be compared in an ASCII case-insensitive manner by user agents for the purposes of comparing with the scheme part of URLs that they consider against the list of registered handlers.The scheme value, if it contains a colon (as in "
mailto:
"), will never match anything, since schemes don’t contain colons.If the
registerProtocolHandler()
method is invoked with a scheme that is neither a safelisted scheme nor a scheme whose value starts with the substring "web+
" and otherwise contains only lowercase ASCII letters, and whose length is at least five characters (including the "web+
" prefix), the user agent must throw a "SyntaxError
"DOMException
.The following schemes are the safelisted schemes:
bitcoin
geo
im
irc
ircs
magnet
mailto
mms
news
nntp
openpgp4fpr
sip
sms
smsto
ssh
tel
urn
webcal
wtai
xmpp
This list can be changed. If there are schemes that should be added, please send feedback.
This list excludes any schemes that could reasonably be expected to be supported inline, e.g., in an
iframe
, such ashttp
or (more theoretically)gopher
. If those were supported, they could potentially be used in man-in-the-middle attacks, by replacing pages that have frames with such content with content under the control of the protocol handler. If the user agent has native support for the schemes, this could further be used for cookie-theft attacks. - url
-
A string used to build the URL of the page that will handle the requests.
User agents must throw a "
SyntaxError
"DOMException
if the url argument passed to one of these methods does not contain the exact literal string "%s
".User agents must throw a "
SyntaxError
"DOMException
if parsing the url argument relative to the API base URL specified by the entry settings object is not successful.The resulting URL string would by definition not be a valid URL as it would include the string "
%s
" which is not a valid component in a URL.User agents must throw a "
SecurityError
"DOMException
if the resulting absolute URL has an origin that differs from the origin specified by the entry settings object.This is forcibly the case if the
%s
placeholder is in the scheme, host, or port parts of the URL.The resulting URL string is the proto-URL. It identifies the handler for the purposes of the methods described below.
When the user agent uses this handler, it must replace the first occurrence of the exact literal string "
%s
" in the url argument with an escaped version of the absolute URL of the content in question (as defined below), then parse the resulting URL, relative to the API base URL specified by the entry settings object at the time theregisterProtocolHandler()
method was invoked, and then navigate an appropriate browsing context to the resulting URL.To get the escaped version of the absolute URL of the content in question, the user agent must replace every character in that absolute URL that is not a character in the URL default encode set with the result of UTF-8 percent encoding that character.
- title
-
A descriptive title of the handler, which the user agent might use to remind the user what the site in question is.
This section does not define how the pages registered by these methods are used, beyond the requirements on how to process the url value (see above). To some extent, the processing model for navigating across documents defines some cases where these methods are relevant, but in general user agents may use this information wherever they would otherwise consider handing content to native plugins or helper applications.
In addition to the registration method, there is also a method for unregistering a handler.
- window .
navigator
.unregisterProtocolHandler
(scheme, url) -
Unregisters the handler given by the arguments.
The unregisterProtocolHandler()
method must unregister the handler described by the two arguments to the method, where the first
argument gives the scheme and the second gives the string used to build the URL of
the page that will handle the requests.
The first argument must be compared to the schemes for which custom protocol handlers are registered in an ASCII case-insensitive manner to find the relevant handlers.
The second argument must be preprocessed as described below, and if that is successful, must then be matched against the proto-URLs of the relevant handlers to find the described handler.
The second argument of the two methods described above must be preprocessed as follows:
-
If the string does not contain the substring "
%s
", abort these steps. There’s no matching handler. -
Parse the string relative to the entry settings object. If this fails, then throw a "
SyntaxError
"DOMException
. -
If the resulting URL record’s origin is not the same origin as the origin specified by the entry settings object, throw a "
SecurityError
"DOMException
. -
Return the resulting URL string as the result of preprocessing the argument.
7.6.1.3.1. Security and privacy
These mechanisms can introduce a number of concerns, in particular privacy concerns.
Hijacking all Web usage. User agents should not allow schemes that are key to its normal operation, such as
http
orhttps
, to be rerouted through third-party sites. This would allow a user’s activities to be trivially tracked, and would allow user information, even in secure connections, to be collected.Hijacking defaults. User agents are strongly urged to not automatically change any defaults, as this could lead the user to send data to remote hosts that the user is not expecting. New handlers registering themselves should never automatically cause those sites to be used.
Registration spamming. User agents should consider the possibility that a site will attempt to register a large number of handlers, possibly from multiple domains (e.g., by redirecting through a series of pages each on a different domain, and each registering a scheme handler — analogous practices abusing other Web browser features have been used by pornography Web sites for many years). User agents should gracefully handle such hostile attempts, protecting the user.
Misleading titles. User agents should not rely wholly on the title argument to the methods when presenting the registered handlers to the user, since sites could easily lie. For example, a site
hostile.example.net
could claim that it was registering the "Cuddly Bear Happy Scheme Handler". User agents should therefore use the handler’s domain in any UI along with any title.Hostile handler metadata. User agents should protect against typical attacks against strings embedded in their interface, for example ensuring that markup or escape characters in such strings are not executed, that null bytes are properly handled, that over-long strings do not cause crashes or buffer overruns, and so forth.
Leaking Intranet URLs. The mechanism described in this section can result in secret Intranet URLs being leaked, in the following manner:
- The user registers a third-party content handler as the default handler for a scheme.
- The user then browses his corporate Intranet site and accesses a link that uses that scheme.
- The user agent contacts the third party and hands the third party the URL to the Intranet content.
No actual confidential file data is leaked in this manner, but the URLs themselves could contain confidential information. For example, the URL could be
cuddly://www.corp.example.com/upcoming-aquisitions/the-sample-company.egf
, which might tell the third party that Example Corporation is intending to merge with The Sample Company. Implementors might wish to consider allowing administrators to disable this feature for certain subdomains, or schemes.Leaking credentials. User agents must never send username or password information in the URLs that are escaped and included sent to the handler sites. User agents may even avoid attempting to pass to Web-based handlers the URLs of resources that are known to require authentication to access, as such sites would be unable to access the resources in question without prompting the user for credentials themselves (a practice that would require the user to know whether to trust the third-party handler, a decision many users are unable to make or even understand).
Interface interference. User agents should be prepared to handle intentionally long arguments to the methods. For example, if the user interface exposed consists of an "accept" button and a "deny" button, with the "accept" binding containing the name of the handler, it’s important that a long name not cause the "deny" button to be pushed off the screen.
Fingerprinting users. Since a site can detect if it has attempted to register a particular handler or not, whether or not the user responds, the mechanism can be used to store data. User agents are therefore strongly urged to treat registrations in the same manner as cookies: clearing cookies for a site should also clear all registrations for that site, and disabling cookies for a site should also disable registrations.
7.6.1.4. Cookies
[NoInterfaceObject] interface NavigatorCookies { readonly attribute boolean cookieEnabled; };
- window .
navigator
.cookieEnabled
- Returns false if setting a cookie will be ignored, and true otherwise.
The cookieEnabled
attribute must
return true if the user agent attempts to handle cookies according to the cookie specification,
and false if it ignores cookie change requests. [COOKIES]
7.6.1.5. Plugins
[NoInterfaceObject] interface NavigatorPlugins { [SameObject] readonly attribute PluginArray plugins; [SameObject] readonly attribute MimeTypeArray mimeTypes; boolean javaEnabled(); };
interface PluginArray { void refresh(optional boolean reload = false); readonly attribute unsigned long length; getter Plugin? item(unsigned long index); getter Plugin? namedItem(DOMString name); };
interface MimeTypeArray { readonly attribute unsigned long length; getter MimeType? item(unsigned long index); getter MimeType? namedItem(DOMString name); };
interface Plugin { readonly attribute DOMString name; readonly attribute DOMString description; readonly attribute DOMString filename; readonly attribute unsigned long length; getter MimeType? item(unsigned long index); getter MimeType? namedItem(DOMString name); };
interface MimeType { readonly attribute DOMString type; readonly attribute DOMString description; readonly attribute DOMString suffixes; // comma-separated readonly attribute Plugin enabledPlugin; };
- window .
navigator
.plugins
.refresh
( [ refresh ] ) - Updates the lists of supported plugins and MIME types for this page, and reloads the page if the lists have changed.
- window .
navigator
.plugins
.length
- Returns the number of plugins, represented by
Plugin
objects, that the user agent reports. - plugin = window .
navigator
.plugins
.item
(index)- window .
navigator
.plugins
[index] - window .
- Returns the specified
Plugin
object. - plugin = window .
navigator
.plugins
.item
(name)- window .
navigator
.plugins
[name] - window .
- Returns the
Plugin
object for the plugin with the given name. - window .
navigator
.mimeTypes
.length
- Returns the number of MIME types, represented by
MimeType
objects, supported by the plugins that the user agent reports. - mimeType = window .
navigator
.mimeTypes
.item
(index)- window .
navigator
.mimeTypes
[index] - window .
- Returns the specified
MimeType
object. - mimeType = window .
navigator
.mimeTypes
.item
(name)- window .
navigator
.mimeTypes
[name] - window .
- Returns the
MimeType
object for the given MIME type. - plugin .
name
- Returns the plugin’s name.
- plugin .
description
- Returns the plugin’s description.
- plugin .
filename
- Returns the plugin library’s filename, if applicable on the current platform.
- plugin .
length
- Returns the number of MIME types, represented by
MimeType
objects, supported by the plugin. - mimeType = plugin .
item
(index)- plugin[index]
- Returns the specified
MimeType
object. - mimeType = plugin .
item
(name)- plugin[name]
- Returns the
MimeType
object for the given MIME type. - mimeType .
type
- Returns the MIME type.
- mimeType .
description
- Returns the MIME type’s description.
- mimeType .
suffixes
- Returns the MIME type’s typical file extensions, in a comma-separated list.
- mimeType .
enabledPlugin
- Returns the
Plugin
object that implements this MIME type. - window .
navigator
.javaEnabled()
- Returns true if there’s a plugin that supports the MIME type "
application/x-java-vm
".
The plugins
attribute must
return a PluginArray
object.
The mimeTypes
attribute must
return a MimeTypeArray
object.
A PluginArray
object represents none, some, or all of the plugins supported by the user agent, each of which is represented by a Plugin
object. Each of these Plugin
objects may be hidden plugins. A can’t
be enumerated, but can still be inspected by using its name.
The fewer plugins are represented by the PluginArray
object, and of those, the more that are , the more the user’s privacy will be protected. Each exposed plugin
increases the number of bits that can be derived for fingerprinting. Hiding a plugin helps, but
unless it is an extremely rare plugin, it is likely that a site attempting to derive the list of
plugins can still determine whether the plugin is supported or not by probing for it by name (the
names of popular plugins are widely known). Therefore not exposing a plugin at all is preferred.
Unfortunately, many legacy sites use this feature to determine, for example, which plugin to use
to play video. Not exposing any plugins at all might therefore not be entirely plausible.
The PluginArray
objects created by a user agent must not be live. The
set of plugins represented by the objects must not change once an object is created, except when
it is updated by the refresh()
method.
Each plugin represented by a PluginArray
can support a number of MIME types. For each such plugin, the user agent must
pick one or more of these MIME types to be those that are explicitly supported.
The explicitly supported MIME types of
a plugin are those that are exposed through the Plugin
and MimeTypeArray
interfaces. As with plugins themselves, any variation between users regarding what is exposed
allows sites to fingerprint users. User agents are therefore encouraged to expose the same MIME types for all users of a plugin, regardless of the
actual types supported... at least, within the constraints imposed by compatibility with legacy
content.
The supported property indices of a PluginArray
object are the
numbers from zero to the number of non- plugins represented by the object, if any.
The length
attribute must return the
number of non- plugins represented by the object.
The item()
method of a PluginArray
object must return null if the argument is not one of the object’s supported property indices, and otherwise must return the result of running the
following steps, using the method’s argument as index:
- Let list be the
Plugin
objects representing the non- plugins represented by thePluginArray
object. - Sort list alphabetically by the
name
of eachPlugin
. - Return the indexth entry in list.
It is important for privacy that the order of plugins not leak additional information, e.g., the order in which plugins were installed.
The supported property names of a PluginArray
object are the values
of the name
attributes of all the Plugin
objects represented by the PluginArray
object. The
properties exposed in this way must be unenumerable.
The namedItem()
method of a PluginArray
object must return null if the argument is not one of the object’s supported property names, and otherwise must return the Plugin
object, of those represented by the PluginArray
object, that has a name
equal to the method’s argument.
The refresh()
method of the PluginArray
object of a Navigator
object, when invoked, must check to
see if any plugins have been installed or reconfigured since the user
agent created the PluginArray
object. If so, and the method’s argument is true, then
the user agent must act as if the location.reload()
method was called instead. Otherwise, the user agent must update the PluginArray
object and MimeTypeArray
object created for attributes of that Navigator
object, and the Plugin
and MimeType
objects created
for those PluginArray
and MimeTypeArray
objects, using the same Plugin
objects for cases where the name
is the same, and the same MimeType
objects for
cases where the type
is the same, and creating new objects
for cases where there were no matching objects immediately prior to the refresh()
call. Old Plugin
and MimeType
objects must continue to return the same values that they had prior to
the update, though naturally now the data is stale and may appear inconsistent (for example, an
old MimeType
entry might list as its enabledPlugin
a Plugin
object that no longer lists that MimeType
as a supported MimeType
).
A MimeTypeArray
object represents the MIME types explicitly supported by plugins supported by the user
agent, each of which is represented by a MimeType
object.
The MimeTypeArray
objects created by a user agent must not be live.
The set of MIME types represented by the objects must not change once an object is created, except
when it is updated by the PluginArray
object’s refresh()
method.
The supported property indices of a MimeTypeArray
object are the
numbers from zero to the number of MIME types explicitly
supported by non- plugins represented by the corresponding PluginArray
object, if
any.
The length
attribute must return the
number of MIME types explicitly supported by non- plugins represented by the
corresponding PluginArray
object, if any.
The item()
method of a MimeTypeArray
object must return null if the argument is not one of the object’s supported property indices, and otherwise must return the result of running the
following steps, using the method’s argument as index:
- Let list be the
MimeType
objects representing the MIME types explicitly supported by non- plugins represented by the correspondingPluginArray
object, if any. - Sort list alphabetically by the
type
of eachMimeType
. - Return the indexth entry in list.
It is important for privacy that the order of MIME types not leak additional information, e.g., the order in which plugins were installed.
The supported property names of a MimeTypeArray
object are the values
of the type
attributes of all the MimeType
objects represented by the MimeTypeArray
object. The properties exposed in this way
must be unenumerable.
The namedItem()
method of a MimeTypeArray
object must return null if the argument is not one of the object’s supported property names, and otherwise must return the MimeType
object
that has a type
equal to the method’s argument.
A Plugin
object represents a plugin. It has
several attributes to provide details about the plugin, and can be enumerated to obtain the list
of MIME types that it explicitly
supports.
The Plugin
objects created by a user agent must not be live. The set of MIME types represented by the objects, and the values of the
objects' attributes, must not change once an object is created, except when updated by the PluginArray
object’s refresh()
method.
The reported MIME types for a Plugin
object are the MIME types explicitly supported by the corresponding plugin when this object was last created or updated by PluginArray.refresh()
, whichever happened most
recently.
The supported property indices of a Plugin
object
are the numbers from zero to the number of reported MIME types.
The length
attribute must return the number
of reported MIME types.
The item()
method of a Plugin
object must return null if the argument is not one of the
object’s supported property indices, and otherwise must return the result of running
the following steps, using the method’s argument as index:
- Let list be the
MimeType
objects representing the reported MIME types. - Sort list alphabetically by the
type
of eachMimeType
. - Return the indexth entry in list.
It is important for privacy that the order of MIME types not leak additional information, e.g., the order in which plugins were installed.
The supported property names of a Plugin
object
are the values of the type
attributes of the MimeType
objects representing the reported MIME types. The properties
exposed in this way must be unenumerable.
The namedItem()
method of a Plugin
object must return null if the argument is not one of the
object’s supported property names, and otherwise must return the MimeType
object that has a type
equal to the
method’s argument.
The name
attribute must return the plugin’s name.
The description
and filename
attributes must return user-agent-defined
(or, in all likelihood, plugin-defined) strings. In each case, the same string must
be returned each time, except that the strings returned may change when the PluginArray.refresh()
method updates the object.
If the values returned by the description
or filename
attributes vary between versions of a plugin, they can be used both as a fingerprinting vector and, even more importantly,
as a trivial way to determine what security vulnerabilities a plugin (and thus a
browser) may have. It is thus highly recommended that the description
attribute just return the same value as the name
attribute, and that the filename
attribute return the empty string.
A MimeType
object represents a MIME type that is, or was, explicitly supported by a plugin.
The MimeType
objects created by a user agent must not be live. The
values of the objects' attributes must not change once an object is created, except when updated
by the PluginArray
object’s refresh()
method.
The type
attribute must return the valid MIME type with no parameters describing the MIME type.
The description
and suffixes
attributes must return
user-agent-defined (or, in all likelihood, plugin-defined) strings. In each case, the
same string must be returned each time, except that the strings returned may change when the PluginArray.refresh()
method updates the object.
If the values returned by the description
or suffixes
attributes vary between versions of a plugin, they can be used both as a fingerprinting vector and, even more importantly,
as a trivial way to determine what security vulnerabilities a plugin (and thus a
browser) may have. It is thus highly recommended that the description
attribute just return the same value as the type
attribute, and that the suffixes
attribute return the empty string.
Commas in the suffixes
attribute are
interpreted as separating subsequent filename extensions, as in "htm,html
".
The enabledPlugin
attribute must
return the Plugin
object that represents the plugin that explicitly supported the MIME type that this MimeType
object represents when this object was last created or updated by PluginArray.refresh()
, whichever happened most
recently.
The javaEnabled()
attribute
must return true if the user agent supports a plugin that supports the MIME
type "application/x-java-vm
"; otherwise it must return false.
7.7. Images
[Exposed=(Window, Worker)] interface ImageBitmap { readonly attribute unsigned long width; readonly attribute unsigned long height; }; typedef (HTMLImageElement or HTMLVideoElement or HTMLCanvasElement or Blob or ImageData or CanvasRenderingContext2D or ImageBitmap) ImageBitmapSource;
[NoInterfaceObject, Exposed=(Window, Worker)] interface ImageBitmapFactories { Promise<ImageBitmap> createImageBitmap(ImageBitmapSource image); Promise<ImageBitmap> createImageBitmap(ImageBitmapSource image, long sx, long sy, long sw, long sh); }; Window implements ImageBitmapFactories; WorkerGlobalScope implements ImageBitmapFactories;
An ImageBitmap
object represents a bitmap image that can be painted to a canvas
without undue latency.
The exact judgement of what is undue latency of this is left up to the implementer, but in general if making use of the bitmap requires network I/O, or even local disk I/O, then the latency is probably undue; whereas if it only requires a blocking read from a GPU or system RAM, the latency is probably acceptable.
- promise = Window .
createImageBitmap
(image [, sx, sy, sw, sh ] ) -
Takes image, which can be an
img
element,video
, orcanvas
element, aBlob
object, anImageData
object, aCanvasRenderingContext2D
object, or anotherImageBitmap
object, and returns a promise that is resolved when a newImageBitmap
is created.If no
ImageBitmap
object can be constructed, for example because the provided image data is not actually an image, then the promise is rejected instead.If sx, sy, sw, and sh arguments are provided, the source image is cropped to the given pixels, with any pixels missing in the original replaced by transparent black. These coordinates are in the source image’s pixel coordinate space, not in CSS pixels.
Rejects the promise with an
InvalidStateError
exception if the source image is not in a valid state (e.g., animg
element that hasn’t finished loading, or aCanvasRenderingContext2D
object whose bitmap data has zero length along one or both dimensions, or anImageData
object whose data isdata
attribute has been neutered). Rejects the promise with a "SyntaxError
"DOMException
if the script is not allowed to access the image data of the source image (e.g., avideo
that is CORS-cross-origin, or acanvas
being drawn on by a script in a worker from another origin). - imageBitmap .
width
-
Returns the intrinsic width of the image, in CSS pixels.
- imageBitmap .
height
-
Returns the intrinsic height of the image, in CSS pixels.
An ImageBitmap
object always has associated bitmap data, with a width and a height.
However, it is possible for this data to be corrupted. If an ImageBitmap
object’s
media data can be decoded without errors, it is said to be fully decodable.
An ImageBitmap
object’s bitmap has an origin-clean flag, which indicates whether the
bitmap is tainted by content from a different origin. The flag is initially set to
true and may be changed to false by the steps of createImageBitmap()
.
An ImageBitmap
object can be obtained from a variety of different objects, using
the createImageBitmap()
method. When invoked, the method must act as follows:
- If image is an
img
element -
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
IndexSizeError
exception and abort these steps. - If the
img
element is not completely available, then return a promise rejected with anInvalidStateError
exception and abort these steps. - If the
img
element’s media data is not a bitmap (e.g., it’s a vector graphic), then return a promise rejected with anInvalidStateError
exception and abort these steps. - Create a new
ImageBitmap
object. - Let the
ImageBitmap
object’s bitmap data be a copy of theimg
element’s media data, cropped to the source rectangle. If this is an animated image, theImageBitmap
object’s bitmap data must only be taken from the default image of the animation (the one that the format defines is to be used when animation is not supported or is disabled), or, if there is no such image, the first frame of the animation. - If the origin of the
img
element’s image is not the same origin as the origin specified by the entry settings object, then set the origin-clean flag of theImageBitmap
object’s bitmap to false. - Return a new promise, but continue running these steps in parallel.
- Resolve the promise with the new
ImageBitmap
object as the value.
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
- If image is a
video
element -
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
IndexSizeError
exception and abort these steps. - If the
video
element’snetworkState
attribute isNETWORK_EMPTY
, then return a promise rejected with anInvalidStateError
exception and abort these steps. - If the
video
element’sreadyState
attribute is eitherHAVE_NOTHING
orHAVE_METADATA
, then return a promise rejected with anInvalidStateError
exception and abort these steps. - Create a new
ImageBitmap
object. - Let the
ImageBitmap
object’s bitmap data be a copy of the frame at the current playback position, at the media resource’s intrinsic width and intrinsic height (i.e., after any aspect-ratio correction has been applied), cropped to the source rectangle. - If the origin of the
video
element’s image is not the same origin as the origin specified by the entry settings object, then set the origin-clean flag of theImageBitmap
object’s bitmap to false. - Return a new promise, but continue running these steps in parallel.
- Resolve the promise with the new
ImageBitmap
object as the value.
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
- If image is a
canvas
element -
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
IndexSizeError
exception and abort these steps. - If the
canvas
element’s bitmap has either a horizontal dimension or a vertical dimension equal to zero, then return a promise rejected with anInvalidStateError
exception and abort these steps. - Create a new
ImageBitmap
object. - Let the
ImageBitmap
object’s bitmap data be a copy of thecanvas
element’s bitmap data, cropped to the source rectangle. - Set the origin of the
ImageBitmap
object’s bitmap to the same value as the origin-clean flag of thecanvas
element’s bitmap. - Return a new promise, but continue running these steps in parallel.
- Resolve the promise with the new
ImageBitmap
object as the value.
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
- If image is a
Blob
object -
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
IndexSizeError
exception and abort these steps. -
There are no known native implementations of the File API closed method. Therefore this feature cannot be relied upon.
If image is closed, then return a promise rejected with anInvalidStateError
exception and abort these steps. - Return a new promise, but continue running these steps in parallel.
- Read the
Blob
object’s data. If an error occurs during reading of the object, then reject the promise with null, and abort these steps. - Apply the image sniffing rules to
determine the file format of the image data, with MIME type of the
Blob
(as given by theBlob
object’stype
attribute) giving the official type. - If the image data is not in a supported file format (e.g., it’s not actually an image at all), or if the image data is corrupted in some fatal way such that the image dimensions cannot be obtained, then reject the promise with null, and abort these steps.
- Create a new
ImageBitmap
object. - Let the
ImageBitmap
object’s bitmap data be the image data read from theBlob
object, cropped to the source rectangle. If this is an animated image, theImageBitmap
object’s bitmap data must only be taken from the default image of the animation (the one that the format defines is to be used when animation is not supported or is disabled), or, if there is no such image, the first frame of the animation. - Resolve the promise with the new
ImageBitmap
object as the value.
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
- If image is an
ImageData
object -
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
IndexSizeError
exception and abort these steps. - If the image object’s
data
attribute has been neutered, return a promise rejected with anInvalidStateError
exception and abort these steps. - Create a new
ImageBitmap
object. - Let the
ImageBitmap
object’s bitmap data be the image data given by theImageData
object, cropped to the source rectangle. - Return a new promise, but continue running these steps in parallel.
- Resolve the promise with the new
ImageBitmap
object as the value.
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
- If image is a
CanvasRenderingContext2D
object -
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
IndexSizeError
exception and abort these steps. - If the
CanvasRenderingContext2D
object’s scratch bitmap has either a horizontal dimension or a vertical dimension equal to zero, then return a promise rejected with anInvalidStateError
exception and abort these steps. - Create a new
ImageBitmap
object. - Let the
ImageBitmap
object’s bitmap data be a copy of theCanvasRenderingContext2D
object’s scratch bitmap, cropped to the source rectangle. - Set the origin-clean flag of the
ImageBitmap
object’s bitmap to the same value as the origin-clean flag of theCanvasRenderingContext2D
object’s scratch bitmap - Return a new promise, but continue running these steps in parallel.
- Resolve the promise with the new
ImageBitmap
object as the value.
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
- If image is an
ImageBitmap
object -
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
IndexSizeError
exception and abort these steps. - Create a new
ImageBitmap
object. - Let the
ImageBitmap
object’s bitmap data be a copy of the image argument’s bitmap data, cropped to the source rectangle. - Set the origin-clean flag of the
ImageBitmap
object’s bitmap to the same value as the origin-clean flag of the bitmap of the image argument. - Return a new promise, but continue running these steps in parallel.
- Resolve the promise with the new
ImageBitmap
object as the value.
- If either the sw or sh arguments are specified
but zero, return a promise rejected with an
- Let input be the image data being cropped.
- If the sx, sy, sw, and sh arguments are omitted, return input.
- Place input on an infinite transparent black grid plane, positioned so that it’s top left corner is at the origin of the plane, with the x-coordinate increasing to the right, and the y-coordinate increasing down, and with each pixel in the input image data occupying a cell on the plane’s grid.
-
Let output be the rectangle on the plane denoted by the rectangle whose
corners are the four points (sx, sy), (sx+sw, sy), (sx+sw, sy+sh), (sx, sy+sh).
If either sw or sh are negative, then the top-left corner of this rectangle will be to the left or above the (sx, sy) point. If any of the pixels on this rectangle are outside the area where the input bitmap was placed, then they will be transparent black in output.
- Return output.
The width
attribute must return the ImageBitmap
object’s
width, in CSS pixels.
The height
attribute must return the ImageBitmap
object’s
height, in CSS pixels.
var sprites = {}; function loadMySprites() { var image = new Image(); image.src = 'mysprites.png'; var resolver; var promise = new Promise(function (arg) { resolver = arg }); image.onload = function () { resolver(Promise.all( createImageBitmap(image, 0, 0, 40, 40).then(function (image) { sprites.woman = image }), createImageBitmap(image, 40, 0, 40, 40).then(function (image) { sprites.man = image }), createImageBitmap(image, 80, 0, 40, 40).then(function (image) { sprites.tree = image }), createImageBitmap(image, 0, 40, 40, 40).then(function (image) { sprites.hut = image }), createImageBitmap(image, 40, 40, 40, 40).then(function (image) { sprites.apple = image }), createImageBitmap(image, 80, 40, 40, 40).then(function (image) { sprites.snake = image }), )); }; return promise; } function runDemo() { var canvas = document.querySelector('canvas#demo'); var context = canvas.getContext('2d'); context.drawImage(sprites.tree, 30, 10); context.drawImage(sprites.snake, 70, 10); } loadMySprites().then(runDemo);
7.8. Animation Frames
Each Document
associated with a top-level browsing context has a list of animation frame callbacks, which must be initially empty,
and an animation frame callback identifier, which is a number which must
initially be zero.
When the requestAnimationFrame() method is called, the user agent must run the following steps:
-
Increment document’s animation frame callback identifier by one.
-
Append the method’s argument to document’s list of animation frame callbacks, associated with document’s animation frame callback identifier’s current value
-
Return document’s animation frame callback identifier’s current value
When the cancelAnimationFrame() method is called, the user agent must run the following steps:
-
Find the entry in document’s list of animation frame callbacks that is associated with the value given by the method’s argument handle
-
If there is such an entry, remove it from document’s list of animation frame callbacks
When the user agent is to run the animation frame callbacks for a Document
document with a timestamp now, it must
run the following steps:
-
If the value returned by the document object’s
hidden
attribute is true, abort these steps. [PAGE-VISIBILITY] -
Let callbacks be a list of the entries in document’s list of animation frame callbacks, in the order in which they were added to the list.
-
Set document’s list of animation frame callbacks to the empty list.
-
For each entry in callbacks, in order: invoke the Web IDL callback function, passing now as the only argument, and if an exception is thrown, report the exception. [WEBIDL]
8. The HTML syntax
This section only describes the rules for resources labeled with an HTML MIME type. Rules for XML resources are discussed in the section below entitled "the XHTML syntax".
8.1. Writing HTML documents
This section only applies to documents, authoring tools, and markup generators. In particular, it does not apply to conformance checkers; conformance checkers must use the requirements given in the next section ("parsing HTML documents").
Documents must consist of the following parts, in the given order:
- Optionally, a single U+FEFF BYTE ORDER MARK (BOM) character.
- Any number of comments and space characters.
- A DOCTYPE.
- Any number of comments and space characters.
- The root element, in the form of an
html
element. - Any number of comments and space characters.
The various types of content mentioned above are described in the next few sections.
In addition, there are some restrictions on how character encoding declarations are to be serialized, as discussed in the section on that topic.
Space characters before the root html
element, and space characters at the start
of the html
element and before the head
element, will be dropped when
the document is parsed; space characters after the root html
element will
be parsed as if they were at the end of the body
element. Thus, space characters
around the root element do not round-trip.
It is suggested that newlines be inserted after the DOCTYPE, after any comments that are
before the root element, after the html
element’s start tag (if it is not omitted), and after any comments that are inside the html
element but before the head
element.
Many strings in the HTML syntax (e.g., the names of elements and their attributes) are case-insensitive, but only for uppercase ASCII letters and lowercase ASCII letters. For convenience, in this section this is just referred to as "case-insensitive".
8.1.1. The DOCTYPE
A DOCTYPE is a required preamble.
DOCTYPEs are required for legacy reasons. When omitted, browsers tend to use a different rendering mode that is incompatible with some specifications. Including the DOCTYPE in a document ensures that the browser makes a best-effort attempt at following the relevant specifications.
A DOCTYPE must consist of the following components, in this order:
- A string that is an ASCII case-insensitive match for the string "
<!DOCTYPE
". - One or more space characters.
- A string that is an ASCII case-insensitive match for the string "
html
". - Optionally, a DOCTYPE legacy string or an obsolete permitted DOCTYPE string (defined below).
- Zero or more space characters.
- A U+003E GREATER-THAN SIGN character (>).
In other words, <!DOCTYPE html>
, case-insensitively.
For the purposes of HTML generators that cannot output HTML markup with the short DOCTYPE
"<!DOCTYPE html>
", a DOCTYPE legacy string may be inserted
into the DOCTYPE (in the position defined above). This string must consist of:
- One or more space characters.
- A string that is an ASCII case-insensitive match for the string "
SYSTEM
". - One or more space characters.
- A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the quote mark).
- The literal string "
about:legacy-compat
". - A matching U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (i.e., the same character as in the earlier step labeled quote mark).
In other words, <!DOCTYPE html SYSTEM "about:legacy-compat">
or <!DOCTYPE html SYSTEM 'about:legacy-compat'>
, case-insensitively except for the
part in single or double quotes.
The DOCTYPE legacy string should not be used unless the document is generated from a system that cannot output the shorter string.
To help authors transition from HTML 4.01 and XHTML 1.1, an obsolete permitted DOCTYPE string can be inserted into the DOCTYPE (in the position defined above). This string must consist of:
- One or more space characters.
- A string that is an ASCII case-insensitive match for the string "
PUBLIC
". - One or more space characters.
- A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the first quote mark).
- The string from one of the cells in the first column of the table below. The row to which this cell belongs is the selected row.
- A matching U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (i.e., the same character as in the earlier step labeled first quote mark).
-
If a system identifier is used,
- One or more space characters.
- A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the third quote mark).
- The string from the cell in the second column of the selected row.
- A matching U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (i.e., the same character as in the earlier step labeled third quote mark).
Public identifier | System identifier | System identifier optional? |
---|---|---|
-//W3C//DTD HTML 4.0//EN
| https://www.w3.org/TR/REC-html40/strict.dtd
| Yes |
-//W3C//DTD HTML 4.01//EN
| https://www.w3.org/TR/html4/strict.dtd
| Yes |
-//W3C//DTD XHTML 1.0 Strict//EN
| https://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd
| No |
-//W3C//DTD XHTML 1.1//EN
| https://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd
| No |
A DOCTYPE containing an obsolete permitted DOCTYPE string is an obsolete permitted DOCTYPE. Authors should not use obsolete permitted DOCTYPEs, as they are unnecessarily long.
8.1.2. Elements
There are five different kinds of elements: void elements, raw text elements, escapable raw text elements, foreign elements, and normal elements.
- Void elements
area
,base
,br
,col
,embed
,hr
,img
,input
,keygen
,link
,menuitem
,meta
,param
,source
,track
,wbr
- Raw text elements
script
,style
- escapable raw text elements
textarea
,title
- Foreign elements
- Elements from the MathML namespace and the SVG namespace.
- Normal elements
- All other allowed html elements are normal elements.
Tags are used to delimit the start and end of elements in the markup. Raw text, escapable raw text, and normal elements have a start tag to indicate where they begin, and an end tag to indicate where they end. The start and end tags of certain normal elements can be omitted, as described below in the section on optional tags. Those that cannot be omitted must not be omitted. Void elements only have a start tag; end tags must not be specified for void elements. Foreign elements must either have a start tag and an end tag, or a start tag that is marked as self-closing, in which case they must not have an end tag.
The contents of the element must be placed between just after the start tag (which might be implied, in certain cases) and just before the end tag (which again, might be implied, in certain cases). The exact allowed contents of each individual element depend on the content model of that element, as described earlier in this specification. Elements must not contain content that their content model disallows. In addition to the restrictions placed on the contents by those content models, however, the five types of elements have additional syntactic requirements.
Void elements can’t have any contents (since there’s no end tag, no content can be put between the start tag and the end tag).
Raw text elements can have text, though it has restrictions described below.
Escapable raw text elements can have text and character references, but the text must not contain an ambiguous ampersand. There are also further restrictions described below.
Foreign elements whose start tag is marked as self-closing can’t have any contents (since, again, as there’s no end tag, no content can be put between the start tag and the end tag). Foreign elements whose start tag is not marked as self-closing can have text, character references, CDATA sections, other elements, and comments, but the text must not contain the character U+003C LESS-THAN SIGN (<) or an ambiguous ampersand.
The HTML syntax does not support namespace declarations, even in foreign elements.
For instance, consider the following HTML fragment:
<p> <svg> <metadata> <!-- this is invalid --> <cdr:license xmlns:cdr="https://www.example.com/cdr/metadata" name="MIT"/> </metadata> </svg> </p>
The innermost element, cdr:license
, is actually in the SVG namespace, as
the "xmlns:cdr
" attribute has no effect (unlike in XML). In fact, as the
comment in the fragment above says, the fragment is actually non-conforming. This is because the
SVG specification does not define any elements called "cdr:license
" in the
SVG namespace.
Normal elements can have text, character references, other elements, and comments, but the text must not contain the character U+003C LESS-THAN SIGN (<) or an ambiguous ampersand. Some normal elements also have yet more restrictions on what content they are allowed to hold, beyond the restrictions imposed by the content model and those described in this paragraph. Those restrictions are described below.
Tags contain a tag name, giving the element’s name. HTML elements all have names that only use alphanumeric ASCII characters. In the HTML syntax, tag names, even those for foreign elements, may be written with any mix of lower- and uppercase letters that, when converted to all-lowercase, matches the element’s tag name; tag names are case-insensitive.
8.1.2.1. Start tags
Start tags must have the following format:
- The first character of a start tag must be a U+003C LESS-THAN SIGN character (<).
- The next few characters of a start tag must be the element’s tag name.
- If there are to be any attributes in the next step, there must first be one or more space characters.
- Then, the start tag may have a number of attributes, the syntax for which is described below. Attributes must be separated from each other by one or more space characters.
- After the attributes, or after the tag name if there are no attributes, there may be one or more space characters. (Some attributes are required to be followed by a space. See §8.1.2.3 Attributes below.)
- Then, if the element is one of the void elements, or if the element is a foreign element, then there may be a single U+002F SOLIDUS character (/). This character has no effect on void elements, but on foreign elements it marks the start tag as self-closing.
- Finally, start tags must be closed by a U+003E GREATER-THAN SIGN character (>).
8.1.2.2. End tags
End tags must have the following format:
- The first character of an end tag must be a U+003C LESS-THAN SIGN character (<).
- The second character of an end tag must be a U+002F SOLIDUS character (/).
- The next few characters of an end tag must be the element’s tag name.
- After the tag name, there may be one or more space characters.
- Finally, end tags must be closed by a U+003E GREATER-THAN SIGN character (>).
8.1.2.3. Attributes
Attributes for an element are expressed inside the element’s start tag.
Attributes have a name and a value. Attribute names must consist of one or more characters other than the space characters, U+0000 NULL, U+0022 QUOTATION MARK ("), U+0027 APOSTROPHE ('), U+003E GREATER-THAN SIGN (>), U+002F SOLIDUS (/), and U+003D EQUALS SIGN (=) characters, the control characters, and any characters that are not defined by Unicode. In the HTML syntax, attribute names, even those for foreign elements, may be written with any mix of lower- and uppercase letters that are an ASCII case-insensitive match for the attribute’s name.
Attribute values are a mixture of text and character references, except with the additional restriction that the text cannot contain an ambiguous ampersand.
Attributes can be specified in four different ways:
- Empty attribute syntax
-
Just the attribute name. The value is implicitly the empty string.
In the following example, thedisabled
attribute is given with the empty attribute syntax:<input disabled>
If an attribute using the empty attribute syntax is to be followed by another attribute, then there must be a space character separating the two.
- Unquoted attribute value syntax
-
The attribute name, followed by zero or more space characters, followed by a single U+003D EQUALS SIGN character, followed by zero or more space characters, followed by the attribute value, which, in addition to the requirements given above for attribute values, must not contain any literal space characters, any U+0022 QUOTATION MARK characters ("), U+0027 APOSTROPHE characters ('), U+003D EQUALS SIGN characters (=), U+003C LESS-THAN SIGN characters (<), U+003E GREATER-THAN SIGN characters (>), or U+0060 GRAVE ACCENT characters (`), and must not be the empty string.
In the following example, thevalue
attribute is given with the unquoted attribute value syntax:<input value=yes>
If an attribute using the unquoted attribute syntax is to be followed by another attribute or by the optional U+002F SOLIDUS character (/) allowed in step 6 of the start tag syntax above, then there must be a space character separating the two.
- Single-quoted attribute value syntax
-
The attribute name, followed by zero or more space characters, followed by a single U+003D EQUALS SIGN character, followed by zero or more space characters, followed by a single U+0027 APOSTROPHE character ('), followed by the attribute value, which, in addition to the requirements given above for attribute values, must not contain any literal U+0027 APOSTROPHE characters ('), and finally followed by a second single U+0027 APOSTROPHE character (').
In the following example, thetype
attribute is given with the single-quoted attribute value syntax:<input type='checkbox'>
If an attribute using the single-quoted attribute syntax is to be followed by another attribute, then there must be a space character separating the two.
- Double-quoted attribute value syntax
-
The attribute name, followed by zero or more space characters, followed by a single U+003D EQUALS SIGN character, followed by zero or more space characters, followed by a single U+0022 QUOTATION MARK character ("), followed by the attribute value, which, in addition to the requirements given above for attribute values, must not contain any literal U+0022 QUOTATION MARK characters ("), and finally followed by a second single U+0022 QUOTATION MARK character (").
In the following example, thename
attribute is given with the double-quoted attribute value syntax:<input name="be evil">
If an attribute using the double-quoted attribute syntax is to be followed by another attribute, then there must be a space character separating the two.
There must never be two or more attributes on the same start tag whose names are an ASCII case-insensitive match for each other.
When a foreign element has one of the namespaced attributes given by the local name and namespace of the first and second cells of a row from the following table, it must be written using the name given by the third cell from the same row.
Local name | Namespace | Attribute name |
---|---|---|
actuate
| XLink namespace | xlink:actuate
|
arcrole
| XLink namespace | xlink:arcrole
|
href
| XLink namespace | xlink:href
|
role
| XLink namespace | xlink:role
|
show
| XLink namespace | xlink:show
|
title
| XLink namespace | xlink:title
|
type
| XLink namespace | xlink:type
|
base
| XML namespace | xml:base
|
lang
| XML namespace | xml:lang
|
space
| XML namespace | xml:space
|
xmlns
| XMLNS namespace | xmlns
|
xlink
| XMLNS namespace | xmlns:xlink
|
No other namespaced attribute can be expressed in the HTML syntax.
Whether the attributes in the table above are conforming or not is defined by other specifications (e.g., the SVG and MathML specifications); this section only describes the syntax rules if the attributes are serialized using the HTML syntax.
8.1.2.4. Optional tags
Certain tags can be omitted.
Omitting an element’s start tag in the
situations described below does not mean the element is not present; it is implied, but it is
still there. For example, an HTML document always has a root html
element, even if
the string <html>
doesn’t appear anywhere in the markup.
An html
element’s start tag may be omitted
if the first thing inside the html
element is not a comment.
<html>
"
tag:
<!DOCTYPE HTML> <html> <head> <title>Hello</title> </head> <body> <p>Welcome to this example.</p> </body> </html>
Doing so would make the document look like this:
<!DOCTYPE HTML> <head> <title>Hello</title> </head> <body> <p>Welcome to this example.</p> </body> </html>
This has the exact same DOM. In particular, note that white space around the root element is ignored by the parser. The following example would also have the exact same DOM:
<!DOCTYPE HTML><head> <title>Hello</title> </head> <body> <p>Welcome to this example.</p> </body> </html>
However, in the following example, removing the start tag moves the comment to before the html
element:
<!DOCTYPE HTML> <html> <!-- where is this comment in the DOM? --> <head> <title>Hello</title> </head> <body> <p>Welcome to this example.</p> </body> </html>
With the tag removed, the document actually turns into the same as this:
<!DOCTYPE HTML> <!-- where is this comment in the DOM? --> <html> <head> <title>Hello</title> </head> <body> <p>Welcome to this example.</p> </body> </html>
This is why the tag can only be removed if it is not followed by a comment: removing the tag when there is a comment there changes the document’s resulting parse tree. Of course, if the position of the comment does not matter, then the tag can be omitted, as if the comment had been moved to before the start tag in the first place.
An html
element’s end tag may be omitted if
the html
element is not immediately followed by a comment.
A head
element’s start tag may be omitted if
the element is empty, or if the first thing inside the head
element is an
element.
A head
element’s end tag may be omitted if the head
element is not immediately followed by a space character or a comment.
A body
element’s start tag may be omitted
if the element is empty, or if the first thing inside the body
element is not a space character or a comment, except if the
first thing inside the body
element is a meta
, link
, script
, style
, or template
element.
A body
element’s end tag may be omitted if the body
element is not immediately followed by a comment.
head
element start and end tags, and the body
element start tag, can’t be omitted, because they are surrounded by white
space:
<!DOCTYPE HTML> <html> <head> <title>Hello</title> </head> <body> <p>Welcome to this example.</p> </body> </html>
(The body
and html
element end tags could be omitted without
trouble; any spaces after those get parsed into the body
element anyway.)
Usually, however, white space isn’t an issue. If we first remove the white space we don’t care about:
<!DOCTYPE HTML><html><head><title>Hello</title></head><body><p>Welcome to this example.</p></body></html>
Then we can omit a number of tags without affecting the DOM:
<!DOCTYPE HTML><title>Hello</title><p>Welcome to this example.</p>
At that point, we can also add some white space back:
<!DOCTYPE HTML> <title>Hello</title> <p>Welcome to this example.</p>
This would be equivalent to this document, with the omitted tags shown in their
parser-implied positions; the only white space text node that results from this is the newline at
the end of the head
element:
<!DOCTYPE HTML> <html><head><title>Hello</title> </head><body><p>Welcome to this example.</p></body></html>
An li
element’s end tag may be omitted if the li
element is immediately followed by another li
element or if there is
no more content in the parent element.
A dt
element’s end tag may be omitted if the dt
element is immediately followed by another dt
element or a dd
element.
A dd
element’s end tag may be omitted if the dd
element is immediately followed by another dd
element or a dt
element, or if there is no more content in the parent element.
A p
element’s end tag may be omitted if the p
element is immediately followed by an address
, article
, aside
, blockquote
, details
, div
, dl
, fieldset
, figcaption
, figure
, footer
, form
, h1
, h2
, h3
, h4
, h5
, h6
, header
, hr
, main
, menu
, nav
, ol
, p
, pre
, section, table
, or ul
element, or if there is no more content in the parent element and the parent
element is an HTML element that is not an a
, audio
, del
, ins
, map
, noscript
, or video
element.
<!DOCTYPE HTML><title>Hello</title><p>Welcome to this example.</p>
An rt
element’s end tag may be omitted if the rt
element is immediately followed by an rt
or rp
element,
or if there is no more content in the parent element.
An rp
element’s end tag may be omitted if the rp
element is immediately followed by an rt
or rp
element,
or if there is no more content in the parent element.
An optgroup
element’s end tag may be omitted
if the optgroup
element is
immediately followed by another optgroup
element, or if there is no more content in
the parent element.
An option
element’s end tag may be omitted if
the option
element is immediately followed by another option
element, or
if it is immediately followed by an optgroup
element, or if there is no more content
in the parent element.
A colgroup
element’s start tag may be
omitted if the first thing inside the colgroup
element is a col
element,
and if the element is not immediately preceded by another colgroup
element whose end tag has been omitted. (It can’t be omitted if the element
is empty.)
A colgroup
element’s end tag may be omitted if
the colgroup
element is not immediately followed by a space character or
a comment.
A caption
element’s end tag may be omitted if
the caption
element is not immediately followed by a space character or
a comment.
A thead
element’s end tag may be omitted if
the thead
element is immediately followed by a tbody
or tfoot
element.
A tbody
element’s start tag may be omitted
if the first thing inside the tbody
element is a tr
element, and if the
element is not immediately preceded by a tbody
, thead
, or tfoot
element whose end tag has been omitted. (It
can’t be omitted if the element is empty.)
A tbody
element’s end tag may be omitted if
the tbody
element is immediately followed by a tbody
or tfoot
element, or if there is no more content in the parent element.
A tfoot
element’s end tag may be omitted if
the tfoot
element is immediately followed by a tbody
element, or if
there is no more content in the parent element.
A tr
element’s end tag may be omitted if the tr
element is immediately followed by another tr
element, or if there is
no more content in the parent element.
A td
element’s end tag may be omitted if the td
element is immediately followed by a td
or th
element,
or if there is no more content in the parent element.
A th
element’s end tag may be omitted if the th
element is immediately followed by a td
or th
element,
or if there is no more content in the parent element.
Take this example:
<table> <caption>37547 TEE Electric Powered Rail Car Train Functions (Abbreviated)</caption> <colgroup><col><col><col></colgroup> <thead> <tr> <th>Function</th> <th>Control Unit</th> <th>Central Station</th> </tr> </thead> <tbody> <tr> <td>Headlights</td> <td>✔</td> <td>✔</td> </tr> <tr> <td>Interior Lights</td> <td>✔</td> <td>✔</td> </tr> <tr> <td>Electric locomotive operating sounds</td> <td>✔</td> <td>✔</td> </tr> <tr> <td>Engineer’s cab lighting</td> <td></td> <td>✔</td> </tr> <tr> <td>Station Announcements - Swiss</td> <td></td> <td>✔</td> </tr> </tbody> </table>
The exact same table, modulo some white space differences, could be marked up as follows:
<table> <caption>37547 TEE Electric Powered Rail Car Train Functions (Abbreviated) <colgroup><col><col><col> <thead> <tr> <th>Function <th>Control Unit <th>Central Station <tbody> <tr> <td>Headlights <td>✔ <td>✔ <tr> <td>Interior Lights <td>✔ <td>✔ <tr> <td>Electric locomotive operating sounds <td>✔ <td>✔ <tr> <td>Engineer’s cab lighting <td> <td>✔ <tr> <td>Station Announcements - Swiss <td> <td>✔ </table>
Since the cells take up much less room this way, this can be made even terser by having each row on one line:
<table> <caption>37547 TEE Electric Powered Rail Car Train Functions (Abbreviated) <colgroup><col><col><col> <thead> <tr> <th>Function <th>Control Unit <th>Central Station <tbody> <tr> <td>Headlights <td>✔ <td>✔ <tr> <td>Interior Lights <td>✔ <td>✔ <tr> <td>Electric locomotive operating sounds <td>✔ <td>✔ <tr> <td>Engineer’s cab lighting <td> <td>✔ <tr> <td>Station Announcements - Swiss <td> <td>✔ </table>
The only differences between these tables, at the DOM level, is with the precise position of the (in any case semantically-neutral) white space.
However, a start tag must never be omitted if it has any attributes.
<!DOCTYPE HTML><title>Hello</title><p>Welcome to this example.
If the body
element in this example had to have a class
attribute and the html
element had to have a lang
attribute, the markup would have to become:
<!DOCTYPE HTML><html lang="en"><title>Hello</title><body class="demo"><p>Welcome to this example.
This section assumes that the document is conforming, in particular, that there are no content model violations. Omitting tags in the fashion described in this section in a document that does not conform to the content models described in this specification is likely to result in unexpected DOM differences (this is, in part, what the content models are designed to avoid).
8.1.2.5. Restrictions on content models
For historical reasons, certain elements have extra restrictions beyond even the restrictions given by their content model.
A table
element must not contain tr
elements, even though these
elements are technically allowed inside table
elements according to the content
models described in this specification. (If a tr
element is put inside a table
in the markup, it will in fact imply a tbody
start tag before
it.)
A single newline may be placed immediately after the start tag of pre
and textarea
elements.
This does not affect the processing of the element. The otherwise optional newline must be included if the element’s contents
themselves start with a newline (because otherwise the
leading newline in the contents would be treated like the optional newline, and ignored).
8.1.2.6. Restrictions on the contents of raw text and escapable raw text elements
The text in raw text and escapable raw text
elements must not contain any occurrences of the string "</
"
(U+003C LESS-THAN SIGN, U+002F SOLIDUS) followed by characters that case-insensitively match the
tag name of the element followed by one of U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED
(LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), U+0020 SPACE, U+003E GREATER-THAN SIGN
(>), or U+002F SOLIDUS (/).
8.1.3. Text
Text is allowed inside elements, attribute values, and comments. Extra constraints are placed on what is and what is not allowed in text based on where the text is to be put, as described in the other sections.
8.1.3.1. Newlines
Newlines in HTML may be represented either as U+000D CARRIAGE RETURN (CR) characters, U+000A LINE FEED (LF) characters, or pairs of U+000D CARRIAGE RETURN (CR), U+000A LINE FEED (LF) characters in that order.
Where character references are allowed, a character reference of a U+000A LINE FEED (LF) character (but not a U+000D CARRIAGE RETURN (CR) character) also represents a newline.
8.1.4. Character references
In certain cases described in other sections, text may be mixed with character references. These can be used to escape characters that couldn’t otherwise legally be included in text.
Character references must start with a U+0026 AMPERSAND character (&). Following this, there are three possible kinds of character references:
- Named character references
- The ampersand must be followed by one of the names given in §8.5 Named character references section, using the same case. The name must be one that is terminated by a U+003B SEMICOLON character (;).
- Decimal numeric character reference
- The ampersand must be followed by a U+0023 NUMBER SIGN character (#), followed by one or more ASCII digits, representing a base-ten integer that corresponds to a Unicode code point that is allowed according to the definition below. The digits must then be followed by a U+003B SEMICOLON character (;).
- Hexadecimal numeric character reference
- The ampersand must be followed by a U+0023 NUMBER SIGN character (#), which must be followed by either a U+0078 LATIN SMALL LETTER X character (x) or a U+0058 LATIN CAPITAL LETTER X character (X), which must then be followed by one or more ASCII hex digits, representing a hexadecimal integer that corresponds to a Unicode code point that is allowed according to the definition below. The digits must then be followed by a U+003B SEMICOLON character (;).
The numeric character reference forms described above are allowed to reference any Unicode code point other than U+0000, U+000D, permanently undefined Unicode characters (noncharacters), surrogates (U+D800–U+DFFF), and control characters other than space characters.
An ambiguous ampersand is a U+0026 AMPERSAND character (&) that is followed by one or more alphanumeric ASCII characters, followed by a U+003B SEMICOLON character (;), where these characters do not match any of the names given in the §8.5 Named character references section.
8.1.5. CDATA sections
CDATA sections must consist of the following components, in this order:
- The string "
<![CDATA[
". - Optionally, text, with the additional restriction that the
text must not contain the string "
]]>
". - The string "
]]>
".
ms
element:
<p>You can add a string to a number, but this stringifies the number:</p> <math> <ms><![CDATA[x<y]]></ms> <mo>+</mo> <mn>3</mn> <mo>=</mo> <ms><![CDATA[x<y3]]></ms> </math>
8.1.6. Comments
Comments must start with the four character sequence U+003C
LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS (<!--
). Following this sequence, the comment may have text, with the additional restriction that the text must not start with
a single U+003E GREATER-THAN SIGN character (>), nor start with a U+002D HYPHEN-MINUS character
(-) followed by a U+003E GREATER-THAN SIGN (>) character, nor contain two consecutive U+002D
HYPHEN-MINUS characters (--
), nor end with a U+002D HYPHEN-MINUS character
(-). Finally, the comment must be ended by the three character sequence U+002D HYPHEN-MINUS,
U+002D HYPHEN-MINUS, U+003E GREATER-THAN SIGN (-->
).
8.2. Parsing HTML documents
This section only applies to user agents, data mining tools, and conformance checkers.
The rules for parsing XML documents into DOM trees are covered by the next section, entitled "the XHTML syntax".
User agents must use the parsing rules described in this section to generate the DOM trees from text/html
resources. Together, these rules define what is referred to as the HTML parser.
While the HTML syntax described in this specification bears a close resemblance to SGML and XML, it is a separate language with its own parsing rules.
Some earlier versions of HTML (in particular from HTML 2.0 to HTML 4.01) were based on SGML and used SGML parsing rules. However, few (if any) web browsers ever implemented true SGML parsing for HTML documents; the only user agents to strictly handle HTML as an SGML application have historically been validators. The resulting confusion — with validators claiming documents to have one representation while widely deployed Web browsers interoperably implemented a different representation — has wasted decades of productivity. This version of HTML thus returns to a non-SGML basis.
Authors interested in using SGML tools in their authoring pipeline are encouraged to use XML tools and the XML serialization of HTML.
This specification defines the parsing rules for HTML documents, whether they are syntactically correct or not. Certain points in the parsing algorithm are said to be parse errors. The error handling for parse errors is well-defined (that’s the processing rules described throughout this specification), but user agents, while parsing an HTML document, may abort the parser at the first parse error that they encounter for which they do not wish to apply the rules described in this specification.
Conformance checkers must report at least one parse error condition to the user if one or more parse error conditions exist in the document and must not report parse error conditions if none exist in the document. Conformance checkers may report more than one parse error condition if more than one parse error condition exists in the document.
Parse errors are only errors with the syntax of HTML. In addition to checking for parse errors, conformance checkers will also verify that the document obeys all the other conformance requirements described in this specification.
For the purposes of conformance checkers, if a resource is determined to be in the HTML syntax, then it is an HTML document.
As stated in the terminology
section, references to element types that do not
explicitly specify a namespace always refer to elements in the HTML namespace. For
example, if the spec talks about "a menuitem
element", then that is an element with
the local name "menuitem
", the namespace "https://www.w3.org/1999/xhtml
", and the interface HTMLMenuItemElement
.
Where possible, references to such elements are hyperlinked to their definition.
8.2.1. Overview of the parsing model
The input to the HTML parsing process consists of a stream of Unicode code points, which is passed through a tokenization stage
followed by a tree construction stage. The output is a Document
object.
Implementations that do not support scripting do not
have to actually create a DOM Document
object, but the DOM tree in such cases is
still used as the model for the rest of the specification.
In the common case, the data handled by the tokenization stage comes from the network, but it can also come from script running in the user
agent, e.g., using the document.write()
API.
There is only one set of states for the tokenizer stage and the tree construction stage, but the tree construction stage is reentrant, meaning that while the tree construction stage is handling one token, the tokenizer might be resumed, causing further tokens to be emitted and processed before the first token’s processing is complete.
... <script> document.write('<p>'); </script> ...
To handle these cases, parsers have a script nesting level, which must be initially set to zero, and a parser pause flag, which must be initially set to false.
8.2.2. The input byte stream
The stream of Unicode code points that comprizes the input to the tokenization stage will be initially seen by the user agent as a stream of bytes (typically coming over the network or from the local file system). The bytes encode the actual characters according to a particular character encoding, which the user agent uses to decode the bytes into characters.
For XML documents, the algorithm user agents are required to use to determine the character encoding is given by the XML specification. This section does not apply to XML documents. [XML]
Usually, the encoding sniffing algorithm defined below is used to determine the character encoding.
Given a character encoding, the bytes in the input byte stream must be converted to characters for the tokenizer’s input stream, by passing the input byte stream and character encoding to decode.
A leading Byte Order Mark (BOM) causes the character encoding argument to be ignored and will itself be skipped.
Bytes or sequences of bytes in the original byte stream that did not conform to the Encoding standard (e.g., invalid UTF-8 byte sequences in a UTF-8 input byte stream) are errors that conformance checkers are expected to report. [ENCODING]
The decoder algorithms describe how to handle invalid input; for security reasons, it is imperative that those rules be followed precisely. Differences in how invalid byte sequences are handled can result in, amongst other problems, script injection vulnerabilities ("XSS").
When the HTML parser is decoding an input byte stream, it uses a character encoding and a confidence. The confidence is either tentative, certain, or irrelevant. The encoding used, and whether the confidence in that encoding is tentative or certain, is used during the parsing to determine whether to change the encoding. If no encoding is necessary, e.g., because the parser is operating on a Unicode stream and doesn’t have to use a character encoding at all, then the confidence is irrelevant.
Some algorithms feed the parser by directly adding characters to the input stream rather than adding bytes to the input byte stream.
8.2.2.1. Parsing with a known character encoding
When the HTML parser is to operate on an input byte stream that has a known definite encoding, then the character encoding is that encoding and the confidence is certain.
8.2.2.2. Determining the character encoding
In some cases, it might be impractical to unambiguously determine the encoding before parsing the document. Because of this, this specification provides for a two-pass mechanism with an optional pre-scan. Implementations are allowed, as described below, to apply a simplified parsing algorithm to whatever bytes they have available before beginning to parse the document. Then, the real parser is started, using a tentative encoding derived from this pre-parse and other out-of-band metadata. If, while the document is being loaded, the user agent discovers a character encoding declaration that conflicts with this information, then the parser can get reinvoked to perform a parse of the document with the real encoding.
User agents must use the following algorithm, called the encoding sniffing algorithm, to determine the character encoding to use when decoding a document in the first pass. This algorithm takes as input any out-of-band metadata available to the user agent (e.g., the Content-Type metadata of the document) and all the bytes available so far, and returns a character encoding and a confidence that is either tentative or certain.
-
If the user has explicitly instructed the user agent to override the document’s character encoding with a specific encoding, optionally return that encoding with the confidence certain and abort these steps.
Typically, user agents remember such user requests across sessions, and in some cases apply them to documents in
iframe
s as well. -
The user agent may wait for more bytes of the resource to be available, either in this step or at any later step in this algorithm. For instance, a user agent might wait 500ms or 1024 bytes, whichever came first. In general preparsing the source to find the encoding improves performance, as it reduces the need to throw away the data structures used when parsing upon finding the encoding information. However, if the user agent delays too long to obtain data to determine the encoding, then the cost of the delay could outweigh any performance improvements from the preparse.
The authoring conformance requirements for character encoding declarations limit them to only appearing in the first 1024 bytes. User agents are therefore encouraged to use the prescan algorithm below (as invoked by these steps) on the first 1024 bytes, but not to stall beyond that.
- If the transport layer specifies a character encoding, and it is supported, return that encoding with the confidence certain, and abort these steps.
-
Optionally prescan the byte stream to determine its encoding. The end condition is that the user agent decides that scanning further bytes would not be efficient. User agents are encouraged to only prescan the first 1024 bytes. User agents may decide that scanning any bytes is not efficient, in which case these substeps are entirely skipped.
The aforementioned algorithm either aborts unsuccessfully or returns a character encoding. If it returns a character encoding, then this algorithm must be aborted, returning the same encoding, with confidence tentative.
-
If the HTML parser for which this algorithm is being run is associated with a
Document
that is itself in a nested browsing context, run these substeps:- Let new document be the
Document
with which the HTML parser is associated. - Let parent document be the
Document
through which new document is nested (the active document of the parent browsing context of new document). - If parent document’s origin is not the same origin as new document’s origin, then abort these substeps.
- If parent document’s character encoding is not an ASCII-compatible encoding, then abort these substeps.
- Return parent document’s character encoding, with the confidence tentative, and abort the encoding sniffing algorithm’s steps.
- Let new document be the
- Otherwise, if the user agent has information on the likely encoding for this page, e.g., based on the encoding of the page when it was last visited, then return that encoding, with the confidence tentative, and abort these steps.
-
The user agent may attempt to autodetect the character encoding from applying frequency analysis or other algorithms to the data stream. Such algorithms may use information about the resource other than the resource’s contents, including the address of the resource. If autodetection succeeds in determining a character encoding, and that encoding is a supported encoding, then return that encoding, with the confidence tentative, and abort these steps. [UNIVCHARDET]
User agents are generally discouraged from attempting to autodetect encodings for resources obtained over the network, since doing so involves inherently non-interoperable heuristics. Attempting to detect encodings based on an HTML document’s preamble is especially tricky since HTML markup typically uses only ASCII characters, and HTML documents tend to begin with a lot of markup rather than with text content.
The UTF-8 encoding has a highly detectable bit pattern. Files from the local file system that contain bytes with values greater than 0x7F which match the UTF-8 pattern are very likely to be UTF-8, while documents with byte sequences that do not match it are very likely not. When a user agent can examine the whole file, rather than just the preamble, detecting for UTF-8 specifically can be especially effective. [PPUTF8] [UTF8DET]
-
Otherwise, return an implementation-defined or user-specified default character encoding, with the confidence tentative.
In controlled environments or in environments where the encoding of documents can be prescribed (for example, for user agents intended for dedicated use in new networks), the comprehensive
UTF-8
encoding is suggested.In other environments, the default encoding is typically dependent on the user’s locale (an approximation of the languages, and thus often encodings, of the pages that the user is likely to frequent). The following table gives suggested defaults based on the user’s locale, for compatibility with legacy content. Locales are identified by BCP 47 language tags. [BCP47] [ENCODING]
Locale language Suggested default encoding ar Arabic windows-1256 ba Bashkir windows-1251 be Belarusian windows-1251 bg Bulgarian windows-1251 cs Czech windows-1250 el Greek ISO-8859-7 et Estonian windows-1257 fa Persian windows-1256 he Hebrew windows-1255 hr Croatian windows-1250 hu Hungarian ISO-8859-2 ja Japanese Shift_JIS kk Kazakh windows-1251 ko Korean euc-kr ku Kurdish windows-1254 ky Kyrgyz windows-1251 lt Lithuanian windows-1257 lv Latvian windows-1257 mk Macedonian windows-1251 pl Polish ISO-8859-2 ru Russian windows-1251 sah Yakut windows-1251 sk Slovak windows-1250 sl Slovenian ISO-8859-2 sr Serbian windows-1251 tg Tajik windows-1251 th Thai windows-874 tr Turkish windows-1254 tt Tatar windows-1251 uk Ukrainian windows-1251 vi Vietnamese windows-1258 zh-CN Chinese (People’s Republic of China) GB18030 zh-TW Chinese (Taiwan) Big5 All other locales windows-1252 The contents of this table are derived from the intersection of Windows, Chrome, and Firefox defaults.
The document’s character encoding must immediately be set to the value returned from this algorithm, at the same time as the user agent uses the returned value to select the decoder to use for the input byte stream.
When an algorithm requires a user agent to prescan a byte stream to determine its encoding, given some defined end condition, then it must run the following steps. These steps either abort unsuccessfully or return a character encoding. If at any point during these steps (including during instances of the get an attribute algorithm invoked by this one) the user agent either runs out of bytes (meaning the position pointer created in the first step below goes beyond the end of the byte stream obtained so far) or reaches its end condition, then abort the prescan a byte stream to determine its encoding algorithm unsuccessfully.
-
Let position be a pointer to a byte in the input byte stream, initially pointing at the first byte.
-
Loop: If position points to:
- A sequence of bytes starting with: 0x3C 0x21 0x2D 0x2D (ASCII '<!--')
-
Advance the position pointer so that it points at the first 0x3E byte which is preceded by two 0x2D bytes (i.e., at the end of an ASCII '-->' sequence) and comes after the 0x3C byte that was found. (The two 0x2D bytes can be the same as those in the '<!--' sequence.)
- A sequence of bytes starting with: 0x3C, 0x4D or 0x6D, 0x45 or 0x65, 0x54 or 0x74, 0x41 or 0x61, and one of 0x09, 0x0A, 0x0C, 0x0D, 0x20, 0x2F (case-insensitive ASCII '<meta' followed by a space or slash)
-
- Advance the position pointer so that it points at the next 0x09, 0x0A, 0x0C, 0x0D, 0x20, or 0x2F byte (the one in sequence of characters matched above).
- Let attribute list be an empty list of strings.
- Let got pragma be false.
- Let need pragma be null.
- Let charset be the null value (which, for the purposes of this algorithm, is distinct from an unrecognized encoding or the empty string).
- Attributes: Get an attribute and its value. If no attribute was computed, then jump to the processing step below.
- If the attribute’s name is already in attribute list, then return to the step labeled attributes.
- Add the attribute’s name to attribute list.
-
Run the appropriate step from the following list, if one applies:
- If the attribute’s name is "
http-equiv
" - If the attribute’s value is "
content-type
", then set got pragma to true. - If the attribute’s name is "
content
" - Apply the algorithm for extracting a character encoding from a
meta
element, giving the attribute’s value as the string to parse. If a character encoding is returned, and if charset is still set to null, let charset be the encoding returned, and set need pragma to true. - If the attribute’s name is "
charset
" - Let charset be the result of getting an encoding from the attribute’s value, and set need pragma to false.
- If the attribute’s name is "
- Return to the step labeled attributes.
- Processing: If need pragma is null, then jump to the step below labeled next byte.
- If need pragma is true but got pragma is false, then jump to the step below labeled next byte.
- If charset is failure, then jump to the step below labeled next byte.
- If charset is a UTF-16 encoding, then set charset to UTF-8.
-
If charset is x-user-defined, then set charset to windows-1252.
-
Abort the prescan a byte stream to determine its encoding algorithm, returning the encoding given by charset.
- A sequence of bytes starting with a 0x3C byte (ASCII <), optionally a 0x2F byte (ASCII /), and finally a byte in the range 0x41-0x5A or 0x61-0x7A (an ASCII letter)
-
- Advance the position pointer so that it points at the next 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x3E (ASCII >) byte.
- Repeatedly get an attribute until no further attributes can be found, then jump to the step below labeled next byte.
- A sequence of bytes starting with: 0x3C 0x21 (ASCII '<!')
- A sequence of bytes starting with: 0x3C 0x2F (ASCII '</')
- A sequence of bytes starting with: 0x3C 0x3F (ASCII '<?')
- A sequence of bytes starting with: 0x3C 0x2F (ASCII '</')
-
Advance the position pointer so that it points at the first 0x3E byte (ASCII >) that comes after the 0x3C byte that was found.
- Any other byte
-
Do nothing with that byte.
- Next byte: Move position so it points at the next byte in the input byte stream, and return to the step above labeled loop.
When the prescan a byte stream to determine its encoding algorithm says to get an attribute, it means doing this:
- If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x2F (ASCII /) then advance position to the next byte and redo this step.
- If the byte at position is 0x3E (ASCII >), then abort the get an attribute algorithm. There isn’t one.
- Otherwise, the byte at position is the start of the attribute name. Let attribute name and attribute value be the empty string.
-
Process the byte at position as follows:
- If it is 0x3D (ASCII =), and the attribute name is longer than the empty string
- Advance position to the next byte and jump to the step below labeled value.
- If it is 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space)
- Jump to the step below labeled spaces.
- If it is 0x2F (ASCII /) or 0x3E (ASCII >)
- Abort the get an attribute algorithm. The attribute’s name is the value of attribute name, its value is the empty string.
- If it is in the range 0x41 (ASCII A) to 0x5A (ASCII Z)
- Append the Unicode character with code point b+0x20 to attribute name (where b is the value of the byte at position). (This converts the input to lowercase.)
- Anything else
- Append the Unicode character with the same code point as the value of the byte at position to attribute name. (It doesn’t actually matter how bytes outside the ASCII range are handled here, since only ASCII characters can contribute to the detection of a character encoding.)
- Advance position to the next byte and return to the previous step.
- Spaces: If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space) then advance position to the next byte, then, repeat this step.
- If the byte at position is not 0x3D (ASCII =), abort the get an attribute algorithm. The attribute’s name is the value of attribute name, its value is the empty string.
- Advance position past the 0x3D (ASCII =) byte.
- Value: If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space) then advance position to the next byte, then, repeat this step.
-
Process the byte at position as follows:
- If it is 0x22 (ASCII ") or 0x27 (ASCII ')
-
- Let b be the value of the byte at position.
- Quote loop: Advance position to the next byte.
- If the value of the byte at position is the value of b, then advance position to the next byte and abort the "get an attribute" algorithm. The attribute’s name is the value of attribute name, and its value is the value of attribute value.
- Otherwise, if the value of the byte at position is in the range 0x41 (ASCII A) to 0x5A (ASCII Z), then append a Unicode character to attribute value whose code point is 0x20 more than the value of the byte at position.
- Otherwise, append a Unicode character to attribute value whose code point is the same as the value of the byte at position.
- Return to the step above labeled quote loop.
- If it is 0x3E (ASCII >)
- Abort the get an attribute algorithm. The attribute’s name is the value of attribute name, its value is the empty string.
- If it is in the range 0x41 (ASCII A) to 0x5A (ASCII Z)
- Append the Unicode character with code point b+0x20 to attribute value (where b is the value of the byte at position). Advance position to the next byte.
- Anything else
- Append the Unicode character with the same code point as the value of the byte at position to attribute value. Advance position to the next byte.
-
Process the byte at position as
follows:
- If it is 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x3E (ASCII >)
- Abort the get an attribute algorithm. The attribute’s name is the value of attribute name and its value is the value of attribute value.
- If it is in the range 0x41 (ASCII A) to 0x5A (ASCII Z)
- Append the Unicode character with code point b+0x20 to attribute value (where b is the value of the byte at position).
- Anything else
- Append the Unicode character with the same code point as the value of the byte at position to attribute value.
- Advance position to the next byte and return to the previous step.
For the sake of interoperability, user agents should not use a pre-scan algorithm that returns different results than the one described above. (But, if you do, please at least let us know, so that we can improve this algorithm and benefit everyone...)
8.2.2.3. Character encodings
User agents must support the encodings defined in the WHATWG Encoding specification, including, but not limited to,
UTF-8, ISO-8859-2, ISO-8859-8, windows-1250, windows-1251, windows-1252, windows-1254, windows-1256, windows-1257, gb18030, Big5, ISO-2022-JP, Shift_JIS, EUC-KR, UTF-16BE, UTF-16LE, and x-user-defined. User agents must not support other encodings.
The above prohibits supporting, for example, CESU-8, UTF-7, BOCU-1, SCSU, EBCDIC, and UTF-32. This specification does not make any attempt to support prohibited encodings in its algorithms; support and use of prohibited encodings would thus lead to unexpected behavior. [CESU8] [RFC2152] [BOCU1] [SCSU]
8.2.2.4. Changing the encoding while parsing
When the parser requires the user agent to change the encoding, it must run the following steps. This might happen if the encoding sniffing algorithm described above failed to find a character encoding, or if it found a character encoding that was not the actual encoding of the file.
- If the encoding that is already being used to interpret the input stream is a UTF-16 encoding, then set the confidence to certain and abort these steps. The new encoding is ignored; if it was anything but the same encoding, then it would be clearly incorrect.
- If the new encoding is a UTF-16 encoding, then change it to UTF-8.
- If the new encoding is the x-user-defined encoding, then change it to Windows-1252. [ENCODING]
- If the new encoding is identical or equivalent to the encoding that is already being used to interpret the input stream, then set the confidence to certain and abort these steps. This happens when the encoding information found in the file matches what the encoding sniffing algorithm determined to be the encoding, and in the second pass through the parser if the first pass found that the encoding sniffing algorithm described in the earlier section failed to find the right encoding.
- If all the bytes up to the last byte converted by the current decoder have the same Unicode interpretations in both the current encoding and the new encoding, and if the user agent supports changing the converter on the fly, then the user agent may change to the new converter for the encoding on the fly. Set the document’s character encoding and the encoding used to convert the input stream to the new encoding, set the confidence to certain, and abort these steps.
- Otherwise, navigate to the document again, with replacement enabled, and using the same source browsing context, but
this time skip the encoding sniffing algorithm and instead just set the encoding to
the new encoding and the confidence to certain. Whenever possible, this should be done without actually contacting the network
layer (the bytes should be re-parsed from memory), even if, e.g., the document is marked as not
being cacheable. If this is not possible and contacting the network layer would involve repeating
a request that uses a method other than
GET
), then instead set the confidence to certain and ignore the new encoding. The resource will be misinterpreted. User agents may notify the user of the situation, to aid in application development.
This algorithm is only invoked when a new encoding is found declared on a meta
element.
8.2.2.5. Preprocessing the input stream
The input stream consists of the characters pushed into it as the input byte stream is decoded or from the various APIs that directly manipulate the input stream.
Any occurrences of any characters in the ranges U+0001 to U+0008, U+000E to U+001F, U+007F to U+009F, U+FDD0 to U+FDEF, and characters U+000B, U+FFFE, U+FFFF, U+1FFFE, U+1FFFF, U+2FFFE, U+2FFFF, U+3FFFE, U+3FFFF, U+4FFFE, U+4FFFF, U+5FFFE, U+5FFFF, U+6FFFE, U+6FFFF, U+7FFFE, U+7FFFF, U+8FFFE, U+8FFFF, U+9FFFE, U+9FFFF, U+AFFFE, U+AFFFF, U+BFFFE, U+BFFFF, U+CFFFE, U+CFFFF, U+DFFFE, U+DFFFF, U+EFFFE, U+EFFFF, U+FFFFE, U+FFFFF, U+10FFFE, and U+10FFFF are parse errors. These are all control characters or permanently undefined Unicode characters (noncharacters).
Any character that is a not a Unicode character, i.e., any isolated
surrogate, is a parse error. (These can only find their way into the input stream via
script APIs such as document.write()
.)
U+000D CARRIAGE RETURN (CR) characters and U+000A LINE FEED (LF) characters are treated specially. Any LF character that immediately follows a CR character must be ignored, and all CR characters must then be converted to LF characters. Thus, newlines in HTML DOMs are represented by LF characters, and there are never any CR characters in the input to the tokenization stage.
The next input character is the first character in the input stream that has not yet been consumed or explicitly ignored by the requirements in this section. Initially, the next input character is the first character in the input. The current input character is the last character to have been consumed.
The insertion point is the position (just before a character or just before the end
of the input stream) where content inserted using document.write()
is actually inserted. The insertion point is
relative to the position of the character immediately after it, it is not an absolute offset into
the input stream. Initially, the insertion point is undefined.
The "EOF" character in the tables below is a conceptual character representing the end of the input stream. If the parser is a script-created parser, then the end of
the input stream is reached when an explicit "EOF" character (inserted by
the document.close()
method) is consumed. Otherwise, the
"EOF" character is not a real character in the stream, but rather the lack of any further
characters.
The handling of U+0000 NULL characters varies based on where the characters are found. In general, they are ignored except where doing so could plausibly introduce an attack vector. This handling is, by necessity, spread across both the tokenization stage and the tree construction stage.
8.2.3. Parse state
8.2.3.1. The insertion mode
The insertion mode is a state variable that controls the primary operation of the tree construction stage.
Initially, the insertion mode is "initial". It can change to "before html", "before head", "in head", "in head noscript", "after head", "in body", "text", "in table", "in table text", "in caption", "in column group", "in table body", "in row", "in cell", "in select", "in select in table", "in template", "after body", "in frameset", "after frameset", "after after body", and "after after frameset" during the course of the parsing, as described in the tree construction stage. The insertion mode affects how tokens are processed and whether CDATA sections are supported.
Several of these modes, namely "in head", "in body", "in table", and "in select", are special, in that the other modes defer to them at various times. When the algorithm below says that the user agent is to do something "using the rules for the m insertion mode", where m is one of these modes, the user agent must use the rules described under the m insertion mode’s section, but must leave the insertion mode unchanged unless the rules in m themselves switch the insertion mode to a new value.
When the insertion mode is switched to "text" or "in table text", the original insertion mode is also set. This is the insertion mode to which the tree construction stage will return.
Similarly, to parse nested template
elements, a stack of template insertion
modes is used. It is initially empty. The current template insertion mode is the
insertion mode that was most recently added to the stack of template insertion modes.
The algorithms in the sections below will push insertion modes onto this stack, meaning
that the specified insertion mode is to be added to the stack, and pop insertion modes from
the stack, which means that the most recently added insertion mode must be removed from the
stack.
When the steps below require the user agent to reset the insertion mode appropriately, it means the user agent must follow these steps:
- Let last be false.
- Let node be the last node in the stack of open elements.
- Loop: If node is the first node in the stack of open elements, then set last to true, and, if the parser was originally created as part of the HTML fragment parsing algorithm (fragment case), set node to the context element passed to that algorithm.
-
If node is a
select
element, run these substeps:- If last is true, jump to the step below labeled done.
- Let ancestor be node.
- Loop: If ancestor is the first node in the stack of open elements, jump to the step below labeled done.
- Let ancestor be the node before ancestor in the stack of open elements.
- If ancestor is a
template
node, jump to the step below labeled done. - If ancestor is a
table
node, switch the insertion mode to "in select in table" and abort these steps. - Jump back to the step labeled loop.
- Done: Switch the insertion mode to "in select" and abort these steps.
- If node is a
td
orth
element and last is false, then switch the insertion mode to "in cell" and abort these steps. - If node is a
tr
element, then switch the insertion mode to "in row" and abort these steps. - If node is a
tbody
,thead
, ortfoot
element, then switch the insertion mode to "in table body" and abort these steps. - If node is a
caption
element, then switch the insertion mode to "in caption" and abort these steps. - If node is a
colgroup
element, then switch the insertion mode to "in column group" and abort these steps. - If node is a
table
element, then switch the insertion mode to "in table" and abort these steps. - If node is a
template
element, then switch the insertion mode to the current template insertion mode and abort these steps. - If node is a
head
element and last is false, then switch the insertion mode to "in head" and abort these steps. - If node is a
body
element, then switch the insertion mode to "in body" and abort these steps. - If node is a
frameset
element, then switch the insertion mode to "in frameset" and abort these steps. (fragment case) -
If node is an
html
element, run these substeps:- If the
head
element pointer is null, switch the insertion mode to "before head" and abort these steps. (fragment case) - Otherwise, the
head
element pointer is not null, switch the insertion mode to "after head" and abort these steps.
- If the
- If last is true, then switch the insertion mode to "in body" and abort these steps. (fragment case)
- Let node now be the node before node in the stack of open elements.
- Return to the step labeled loop.
8.2.3.2. The stack of open elements
Initially, the stack of open elements is empty. The stack grows downwards; the topmost node on the stack is the first one added to the stack, and the bottommost node of the stack is the most recently added node in the stack (notwithstanding when the stack is manipulated in a random access fashion as part of the handling for misnested tags).
The "before html" insertion
mode creates the html
root element node, which is then added to the stack.
In the fragment case, the stack of open elements is
initialized to contain an html
element that is created as part of that algorithm. (The fragment case skips the
"before html" insertion mode.)
The html
node, however it is created, is the topmost node of the stack. It only
gets popped off the stack when the parser finishes.
The current node is the bottommost node in this stack of open elements.
The adjusted current node is the context element if the parser was created by the HTML fragment parsing algorithm and the stack of open elements has only one element in it (fragment case); otherwise, the adjusted current node is the current node.
Elements in the stack of open elements fall into the following categories:
- Special
- The following elements have varying levels of special parsing rules: HTML’s
address
,applet
,area
,article
,aside
,base
,basefont
,bgsound
,blockquote
,body
,br
,button
,caption
,center
,col
,colgroup
,dd
,details
,dir
,div
,dl
,dt
,embed
,fieldset
,figcaption
,figure
,footer
,form
,frame
,frameset
,h1
,h2
,h3
,h4
,h5
,h6
,head
,header
,hr
,html
,iframe
,img
,input
,li
,link
,listing
,main
,marquee
,menu
,menuitem
,meta
,nav
,noembed
,noframes
,noscript
,object
,ol
,p
,param
,plaintext
,pre
,script
,section
,select
,source
,style
,summary
,table
,tbody
,td
,template
,textarea
,tfoot
,th
,thead
,title
,tr
,track
,ul
,wbr
, andxmp
; MathML’smi
,mo
,mn
,ms
,mtext
, andannotation-xml
; and SVG’sforeignObject
,desc
, andtitle
. - Formatting
- The following HTML elements are those that end up in the list of active formatting
elements:
a
,b
,big
,code
,em
,font
,i
,nobr
,s
,small
,strike
,strong
,tt
, andu
. - Ordinary
- All other elements found while parsing an HTML document.
The stack of open elements is said to have an element target node in a specific scope consisting of a list of element types list when the following algorithm terminates in a match state:
- Initialize node to be the current node (the bottommost node of the stack).
- If node is the target node, terminate in a match state.
- Otherwise, if node is one of the element types in list, terminate in a failure state.
- Otherwise, set node to the previous entry in the stack of open
elements and return to step 2. (This will never fail, since the loop will always terminate
in the previous step if the top of the stack — an
html
element — is reached.)
The stack of open elements is said to have a particular element in scope when it has that element in the specific scope consisting of the following element types:
applet
in the HTML namespacecaption
in the HTML namespacehtml
in the HTML namespacetable
in the HTML namespacetd
in the HTML namespaceth
in the HTML namespacemarquee
in the HTML namespaceobject
in the HTML namespacetemplate
in the HTML namespacemi
in the MathML namespacemo
in the MathML namespacemn
in the MathML namespacems
in the MathML namespacemtext
in the MathML namespaceannotation-xml
in the MathML namespaceforeignObject
in the SVG namespacedesc
in the SVG namespacetitle
in the SVG namespace
The stack of open elements is said to have a particular element in list item scope when it has that element in the specific scope consisting of the following element types:
- All the element types listed above for the has an element in scope algorithm.
ol
in the HTML namespaceul
in the HTML namespace
The stack of open elements is said to have a particular element in button scope when it has that element in the specific scope consisting of the following element types:
- All the element types listed above for the has an element in scope algorithm.
button
in the HTML namespace
The stack of open elements is said to have a particular element in table scope when it has that element in the specific scope consisting of the following element types:
html
in the HTML namespacetable
in the HTML namespacetemplate
in the HTML namespace
The stack of open elements is said to have a particular element in select scope when it has that element in the specific scope consisting of all element types except the following:
optgroup
in the HTML namespaceoption
in the HTML namespace
Nothing happens if at any time any of the elements in the stack of open elements are moved to a new location in, or removed from, the Document
tree. In particular,
the stack is not changed in this situation. This can cause, amongst other strange effects, content
to be appended to nodes that are no longer in the DOM.
In some cases (namely, when closing misnested formatting elements), the stack is manipulated in a random-access fashion.
8.2.3.3. The list of active formatting elements
Initially, the list of active formatting elements is empty. It is used to handle mis-nested formatting element tags.
The list contains elements in the formatting category, and markers. The markers are inserted when entering applet
elements, buttons, object
elements, marquees, table cells, and table captions, and
are used to prevent formatting from "leaking" into applet
elements, buttons, object
elements, marquees, and tables.
In addition, each element in the list of active formatting elements is associated with the token for which it was created, so that further elements can be created for that token if necessary.
When the steps below require the user agent to push onto the list of active formatting elements an element element, the user agent must perform the following steps:
-
If there are already three elements in the list of active formatting elements after the last marker, if any, or anywhere in the
list if there are no markers, that have the same tag
name, namespace, and attributes as element, then remove the earliest such
element from the list of active formatting elements. For these purposes, the
attributes must be compared as they were when the elements were created by the parser; two
elements have the same attributes if all their parsed attributes can be paired such that the two
attributes in each pair have identical names, namespaces, and values (the order of the attributes
does not matter).
This is the Noah’s Ark clause. But with three per family instead of two.
- Add element to the list of active formatting elements.
When the steps below require the user agent to reconstruct the active formatting elements, the user agent must perform the following steps:
- If there are no entries in the list of active formatting elements, then there is nothing to reconstruct; stop this algorithm.
- If the last (most recently added) entry in the list of active formatting elements is a marker, or if it is an element that is in the stack of open elements, then there is nothing to reconstruct; stop this algorithm.
- Let entry be the last (most recently added) element in the list of active formatting elements.
- Rewind: If there are no entries before entry in the list of active formatting elements, then jump to the step labeled create.
- Let entry be the entry one earlier than entry in the list of active formatting elements.
- If entry is neither a marker nor an element that is also in the stack of open elements, go to the step labeled rewind.
- Advance: Let entry be the element one later than entry in the list of active formatting elements.
- Create: Insert an HTML element for the token for which the element entry was created, to obtain new element.
- Replace the entry for entry in the list with an entry for new element.
- If the entry for new element in the list of active formatting elements is not the last entry in the list, return to the step labeled advance.
This has the effect of reopening all the formatting elements that were opened in the current body, cell, or caption (whichever is youngest) that haven’t been explicitly closed.
The way this specification is written, the list of active formatting elements always consists of elements in chronological order with the least recently added element first and the most recently added element last (except for while steps 7 to 10 of the above algorithm are being executed, of course).
When the steps below require the user agent to clear the list of active formatting elements up to the last marker, the user agent must perform the following steps:
- Let entry be the last (most recently added) entry in the list of active formatting elements.
- Remove entry from the list of active formatting elements.
- If entry was a marker, then stop the algorithm at this point. The list has been cleared up to the last marker.
- Go to step 1.
8.2.3.4. The element pointers
Initially, the head
element pointer and the form
element pointer are both null.
Once a head
element has been parsed (whether implicitly or explicitly) the head
element pointer gets set to point to this node.
The form
element pointer points to the last form
element that was opened and whose end tag has not yet been seen. It is used to
make form controls associate with forms in the face of dramatically bad markup, for historical
reasons. It is ignored inside template
elements.
8.2.3.5. Other parsing state flags
The scripting flag is set to "enabled" if scripting
was enabled for the Document
with which the parser is associated when the
parser was created, and "disabled" otherwise.
The scripting flag can be enabled even when the parser was originally
created for the HTML fragment parsing algorithm, even though script
elements don’t execute in that case.
The frameset-ok flag is set to "ok" when the parser is created. It is set to "not ok" after certain tokens are seen.
8.2.4. Tokenization
Implementations must act as if they used the following state machine to tokenize HTML. The state machine must start in the §8.2.4.1 Data state. Most states consume a single character, which may have various side-effects, and either switches the state machine to a new state to reconsume the same character, or switches it to a new state to consume the next character, or stays in the same state to consume the next character. Some states have more complicated behavior and can consume several characters before switching to another state. In some cases, the tokenizer state is also changed by the tree construction stage.
The exact behavior of certain states depends on the insertion mode and the stack of open elements. Certain states also use a temporary buffer to track progress.
The output of the tokenization step is a series of zero or more of the following tokens: DOCTYPE, start tag, end tag, comment, character, end-of-file. DOCTYPE tokens have a name, a public identifier, a system identifier, and a force-quirks flag. When a DOCTYPE token is created, its name, public identifier, and system identifier must be marked as missing (which is a distinct state from the empty string), and the force-quirks flag must be set to off (its other state is on). Start and end tag tokens have a tag name, a self-closing flag, and a list of attributes, each of which has a name and a value. When a start or end tag token is created, its self-closing flag must be unset (its other state is that it be set), and its attributes list must be empty. Comment and character tokens have data.
When a token is emitted, it must immediately be handled by the tree construction
stage. The tree construction stage can affect the state of the tokenization stage, and can insert
additional characters into the stream. (For example, the script
element can result in
scripts executing and using the dynamic markup insertion APIs to insert characters
into the stream being tokenized.)
Creating a token and emitting it are distinct actions. It is possible for a token to be created but implicitly abandoned (never emitted), e.g., if the file ends unexpectedly while processing the characters that are being parsed into a start tag token.
When a start tag token is emitted with its self-closing flag set, if the flag is not acknowledged when it is processed by the tree construction stage, that is a parse error.
When an end tag token is emitted with attributes, that is a parse error.
When an end tag token is emitted with its self-closing flag set, that is a parse error.
An appropriate end tag token is an end tag token whose tag name matches the tag name of the last start tag to have been emitted from this tokenizer, if any. If no start tag has been emitted from this tokenizer, then no end tag token is appropriate.
Before each step of the tokenizer, the user agent must first check the parser pause flag. If it is true, then the tokenizer must abort the processing of any nested invocations of the tokenizer, yielding control back to the caller.
The tokenizer state machine consists of the states defined in the following subsections.
8.2.4.1. Data state
Consume the next input character:
- U+0026 AMPERSAND (&)
- Switch to the §8.2.4.2 Character reference in data state.
- U+003C LESS-THAN SIGN (<)
- Switch to the §8.2.4.8 Tag open state.
- U+0000 NULL
- parse error. Emit the current input character as a character token.
- EOF
- Emit an end-of-file token.
- Anything else
- Emit the current input character as a character token.
8.2.4.2. Character reference in data state
Switch to the §8.2.4.1 Data state.
Attempt to consume a character reference, with no additional allowed character.
If nothing is returned, emit a U+0026 AMPERSAND character (&) token.
Otherwise, emit the character tokens that were returned.
8.2.4.3. RCDATA state
Consume the next input character:
- U+0026 AMPERSAND (&)
- Switch to the §8.2.4.4 Character reference in RCDATA state.
- U+003C LESS-THAN SIGN (<)
- Switch to the §8.2.4.11 RCDATA less-than sign state.
- U+0000 NULL
- parse error. Emit a U+FFFD REPLACEMENT CHARACTER character token.
- EOF
- Emit an end-of-file token.
- Anything else
- Emit the current input character as a character token.
8.2.4.4. Character reference in RCDATA state
Switch to the §8.2.4.3 RCDATA state.
Attempt to consume a character reference, with no additional allowed character.
If nothing is returned, emit a U+0026 AMPERSAND character (&) token.
Otherwise, emit the character tokens that were returned.
8.2.4.5. RAWTEXT state
Consume the next input character:
- U+003C LESS-THAN SIGN (<)
- Switch to the §8.2.4.14 RAWTEXT less-than sign state.
- U+0000 NULL
- parse error. Emit a U+FFFD REPLACEMENT CHARACTER character token.
- EOF
- Emit an end-of-file token.
- Anything else
- Emit the current input character as a character token.
8.2.4.6. Script data state
Consume the next input character:
- U+003C LESS-THAN SIGN (<)
- Switch to the §8.2.4.17 Script data less-than sign state.
- U+0000 NULL
- parse error. Emit a U+FFFD REPLACEMENT CHARACTER character token.
- EOF
- Emit an end-of-file token.
- Anything else
- Emit the current input character as a character token.
8.2.4.7. PLAINTEXT state
Consume the next input character:
- U+0000 NULL
- parse error. Emit a U+FFFD REPLACEMENT CHARACTER character token.
- EOF
- Emit an end-of-file token.
- Anything else
- Emit the current input character as a character token.
8.2.4.8. Tag open state
Consume the next input character:
- U+0021 EXCLAMATION MARK (!)
- Switch to the §8.2.4.45 Markup declaration open state.
- U+002F SOLIDUS (/)
- Switch to the §8.2.4.9 End tag open state.
- Uppercase ASCII letter
- Create a new start tag token, set its tag name to the lowercase version of the current input character (add 0x0020 to the character’s code point), then switch to the §8.2.4.10 Tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- Lowercase ASCII letter
- Create a new start tag token, set its tag name to the current input character, then switch to the §8.2.4.10 Tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- U+003F QUESTION MARK (?)
- parse error. Switch to the §8.2.4.44 Bogus comment state.
- Anything else
- parse error. Switch to the §8.2.4.1 Data state. Emit a U+003C LESS-THAN SIGN character token. Reconsume the current input character.
8.2.4.9. End tag open state
Consume the next input character:
- Uppercase ASCII letter
- Create a new end tag token, set its tag name to the lowercase version of the current input character (add 0x0020 to the character’s code point), then switch to the §8.2.4.10 Tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- Lowercase ASCII letter
- Create a new end tag token, set its tag name to the current input character, then switch to the §8.2.4.10 Tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- U+003E GREATER-THAN SIGN (>)
- parse error. Switch to the §8.2.4.1 Data state.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Emit a U+003C LESS-THAN SIGN character token and a U+002F SOLIDUS character token. Reconsume the EOF character.
- Anything else
- parse error. Switch to the §8.2.4.44 Bogus comment state.
8.2.4.10. Tag name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Switch to the §8.2.4.34 Before attribute name state.
- U+002F SOLIDUS (/)
- Switch to the §8.2.4.43 Self-closing start tag state.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current tag token.
- Uppercase ASCII letter
- Append the lowercase version of the current input character (add 0x0020 to the character’s code point) to the current tag token’s tag name.
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current tag token’s tag name.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Append the current input character to the current tag token’s tag name.
8.2.4.11. RCDATA less-than sign state
Consume the next input character:
- U+002F SOLIDUS (/)
- Set the temporary buffer to the empty string. Switch to the §8.2.4.12 RCDATA end tag open state.
- Anything else
- Switch to the §8.2.4.3 RCDATA state. Emit a U+003C LESS-THAN SIGN character token. Reconsume the current input character.
8.2.4.12. RCDATA end tag open state
Consume the next input character:
- Uppercase ASCII letter
- Create a new end tag token, and set its tag name to the lowercase version of the current input character (add 0x0020 to the character’s code point). Append the current input character to the temporary buffer. Finally, switch to the §8.2.4.13 RCDATA end tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- Lowercase ASCII letter
- Create a new end tag token, and set its tag name to the current input character. Append the current input character to the temporary buffer. Finally, switch to the §8.2.4.13 RCDATA end tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- Anything else
- Switch to the §8.2.4.3 RCDATA state. Emit a U+003C LESS-THAN SIGN character token and a U+002F SOLIDUS character token. Reconsume the current input character.
8.2.4.13. RCDATA end tag name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.34 Before attribute name state. Otherwise, treat it as per the "anything else" entry below.
- U+002F SOLIDUS (/)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.43 Self-closing start tag state. Otherwise, treat it as per the "anything else" entry below.
- U+003E GREATER-THAN SIGN (>)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.1 Data state and emit the current tag token. Otherwise, treat it as per the "anything else" entry below.
- Uppercase ASCII letter
- Append the lowercase version of the current input character (add 0x0020 to the character’s code point) to the current tag token’s tag name. Append the current input character to the temporary buffer.
- Lowercase ASCII letter
- Append the current input character to the current tag token’s tag name. Append the current input character to the temporary buffer.
- Anything else
- Switch to the §8.2.4.3 RCDATA state. Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS character token, and a character token for each of the characters in the temporary buffer (in the order they were added to the buffer). Reconsume the current input character.
8.2.4.14. RAWTEXT less-than sign state
Consume the next input character:
- U+002F SOLIDUS (/)
- Set the temporary buffer to the empty string. Switch to the §8.2.4.15 RAWTEXT end tag open state.
- Anything else
- Switch to the §8.2.4.5 RAWTEXT state. Emit a U+003C LESS-THAN SIGN character token. Reconsume the current input character.
8.2.4.15. RAWTEXT end tag open state
Consume the next input character:
- Uppercase ASCII letter
- Create a new end tag token, and set its tag name to the lowercase version of the current input character (add 0x0020 to the character’s code point). Append the current input character to the temporary buffer. Finally, switch to the §8.2.4.16 RAWTEXT end tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- Lowercase ASCII letter
- Create a new end tag token, and set its tag name to the current input character. Append the current input character to the temporary buffer. Finally, switch to the §8.2.4.16 RAWTEXT end tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- Anything else
- Switch to the §8.2.4.5 RAWTEXT state. Emit a U+003C LESS-THAN SIGN character token and a U+002F SOLIDUS character token. Reconsume the current input character.
8.2.4.16. RAWTEXT end tag name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.34 Before attribute name state. Otherwise, treat it as per the "anything else" entry below.
- U+002F SOLIDUS (/)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.43 Self-closing start tag state. Otherwise, treat it as per the "anything else" entry below.
- U+003E GREATER-THAN SIGN (>)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.1 Data state and emit the current tag token. Otherwise, treat it as per the "anything else" entry below.
- Uppercase ASCII letter
- Append the lowercase version of the current input character (add 0x0020 to the character’s code point) to the current tag token’s tag name. Append the current input character to the temporary buffer.
- Lowercase ASCII letter
- Append the current input character to the current tag token’s tag name. Append the current input character to the temporary buffer.
- Anything else
- Switch to the §8.2.4.5 RAWTEXT state. Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS character token, and a character token for each of the characters in the temporary buffer (in the order they were added to the buffer). Reconsume the current input character.
8.2.4.17. Script data less-than sign state
Consume the next input character:
- U+002F SOLIDUS (/)
- Set the temporary buffer to the empty string. Switch to the §8.2.4.18 Script data end tag open state.
- U+0021 EXCLAMATION MARK (!)
- Switch to the §8.2.4.20 Script data escape start state. Emit a U+003C LESS-THAN SIGN character token and a U+0021 EXCLAMATION MARK character token.
- Anything else
- Switch to the §8.2.4.6 Script data state. Emit a U+003C LESS-THAN SIGN character token. Reconsume the current input character.
8.2.4.18. Script data end tag open state
Consume the next input character:
- Uppercase ASCII letter
- Create a new end tag token, and set its tag name to the lowercase version of the current input character (add 0x0020 to the character’s code point). Append the current input character to the temporary buffer. Finally, switch to the §8.2.4.19 Script data end tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- Lowercase ASCII letter
- Create a new end tag token, and set its tag name to the current input character. Append the current input character to the temporary buffer. Finally, switch to the §8.2.4.19 Script data end tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- Anything else
- Switch to the §8.2.4.6 Script data state. Emit a U+003C LESS-THAN SIGN character token and a U+002F SOLIDUS character token. Reconsume the current input character.
8.2.4.19. Script data end tag name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.34 Before attribute name state. Otherwise, treat it as per the "anything else" entry below.
- U+002F SOLIDUS (/)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.43 Self-closing start tag state. Otherwise, treat it as per the "anything else" entry below.
- U+003E GREATER-THAN SIGN (>)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.1 Data state and emit the current tag token. Otherwise, treat it as per the "anything else" entry below.
- Uppercase ASCII letter
- Append the lowercase version of the current input character (add 0x0020 to the character’s code point) to the current tag token’s tag name. Append the current input character to the temporary buffer.
- Lowercase ASCII letter
- Append the current input character to the current tag token’s tag name. Append the current input character to the temporary buffer.
- Anything else
- Switch to the §8.2.4.6 Script data state. Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS character token, and a character token for each of the characters in the temporary buffer (in the order they were added to the buffer). Reconsume the current input character.
8.2.4.20. Script data escape start state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Switch to the §8.2.4.21 Script data escape start dash state. Emit a U+002D HYPHEN-MINUS character token.
- Anything else
- Switch to the §8.2.4.6 Script data state. Reconsume the current input character.
8.2.4.21. Script data escape start dash state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Switch to the §8.2.4.24 Script data escaped dash dash state. Emit a U+002D HYPHEN-MINUS character token.
- Anything else
- Switch to the §8.2.4.6 Script data state. Reconsume the current input character.
8.2.4.22. Script data escaped state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Switch to the §8.2.4.23 Script data escaped dash state. Emit a U+002D HYPHEN-MINUS character token.
- U+003C LESS-THAN SIGN (<)
- Switch to the §8.2.4.25 Script data escaped less-than sign state.
- U+0000 NULL
- parse error. Emit a U+FFFD REPLACEMENT CHARACTER character token.
- EOF
- Switch to the §8.2.4.1 Data state. parse error. Reconsume the EOF character.
- Anything else
- Emit the current input character as a character token.
8.2.4.23. Script data escaped dash state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Switch to the §8.2.4.24 Script data escaped dash dash state. Emit a U+002D HYPHEN-MINUS character token.
- U+003C LESS-THAN SIGN (<)
- Switch to the §8.2.4.25 Script data escaped less-than sign state.
- U+0000 NULL
- parse error. Switch to the §8.2.4.22 Script data escaped state. Emit a U+FFFD REPLACEMENT CHARACTER character token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Switch to the §8.2.4.22 Script data escaped state. Emit the current input character as a character token.
8.2.4.24. Script data escaped dash dash state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Emit a U+002D HYPHEN-MINUS character token.
- U+003C LESS-THAN SIGN (<)
- Switch to the §8.2.4.25 Script data escaped less-than sign state.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.6 Script data state. Emit a U+003E GREATER-THAN SIGN character token.
- U+0000 NULL
- parse error. Switch to the §8.2.4.22 Script data escaped state. Emit a U+FFFD REPLACEMENT CHARACTER character token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Switch to the §8.2.4.22 Script data escaped state. Emit the current input character as a character token.
8.2.4.25. Script data escaped less-than sign state
Consume the next input character:
- U+002F SOLIDUS (/)
- Set the temporary buffer to the empty string. Switch to the §8.2.4.26 Script data escaped end tag open state.
- Uppercase ASCII letter
- Set the temporary buffer to the empty string. Append the lowercase version of the current input character (add 0x0020 to the character’s code point) to the temporary buffer. Switch to the §8.2.4.28 Script data double escape start state. Emit a U+003C LESS-THAN SIGN character token and the current input character as a character token.
- Lowercase ASCII letter
- Set the temporary buffer to the empty string. Append the current input character to the temporary buffer. Switch to the §8.2.4.28 Script data double escape start state. Emit a U+003C LESS-THAN SIGN character token and the current input character as a character token.
- Anything else
- Switch to the §8.2.4.22 Script data escaped state. Emit a U+003C LESS-THAN SIGN character token. Reconsume the current input character.
8.2.4.26. Script data escaped end tag open state
Consume the next input character:
- Uppercase ASCII letter
- Create a new end tag token, and set its tag name to the lowercase version of the current input character (add 0x0020 to the character’s code point). Append the current input character to the temporary buffer. Finally, switch to the §8.2.4.27 Script data escaped end tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- Lowercase ASCII letter
- Create a new end tag token, and set its tag name to the current input character. Append the current input character to the temporary buffer. Finally, switch to the §8.2.4.27 Script data escaped end tag name state. (Don’t emit the token yet; further details will be filled in before it is emitted.)
- Anything else
- Switch to the §8.2.4.22 Script data escaped state. Emit a U+003C LESS-THAN SIGN character token and a U+002F SOLIDUS character token. Reconsume the current input character.
8.2.4.27. Script data escaped end tag name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.34 Before attribute name state. Otherwise, treat it as per the "anything else" entry below.
- U+002F SOLIDUS (/)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.43 Self-closing start tag state. Otherwise, treat it as per the "anything else" entry below.
- U+003E GREATER-THAN SIGN (>)
- If the current end tag token is an appropriate end tag token, then switch to the §8.2.4.1 Data state and emit the current tag token. Otherwise, treat it as per the "anything else" entry below.
- Uppercase ASCII letter
- Append the lowercase version of the current input character (add 0x0020 to the character’s code point) to the current tag token’s tag name. Append the current input character to the temporary buffer.
- Lowercase ASCII letter
- Append the current input character to the current tag token’s tag name. Append the current input character to the temporary buffer.
- Anything else
- Switch to the §8.2.4.22 Script data escaped state. Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS character token, and a character token for each of the characters in the temporary buffer (in the order they were added to the buffer). Reconsume the current input character.
8.2.4.28. Script data double escape start state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+002F SOLIDUS (/)
- U+003E GREATER-THAN SIGN (>)
- U+000A LINE FEED (LF)
- If the temporary buffer is the string "
script
", then switch to the §8.2.4.29 Script data double escaped state. Otherwise, switch to the §8.2.4.22 Script data escaped state. Emit the current input character as a character token. - Uppercase ASCII letter
- Append the lowercase version of the current input character (add 0x0020 to the character’s code point) to the temporary buffer. Emit the current input character as a character token.
- Lowercase ASCII letter
- Append the current input character to the temporary buffer. Emit the current input character as a character token.
- Anything else
- Switch to the §8.2.4.22 Script data escaped state. Reconsume the current input character.
8.2.4.29. Script data double escaped state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Switch to the §8.2.4.30 Script data double escaped dash state. Emit a U+002D HYPHEN-MINUS character token.
- U+003C LESS-THAN SIGN (<)
- Switch to the §8.2.4.32 Script data double escaped less-than sign state. Emit a U+003C LESS-THAN SIGN character token.
- U+0000 NULL
- parse error. Emit a U+FFFD REPLACEMENT CHARACTER character token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Emit the current input character as a character token.
8.2.4.30. Script data double escaped dash state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Switch to the §8.2.4.31 Script data double escaped dash dash state. Emit a U+002D HYPHEN-MINUS character token.
- U+003C LESS-THAN SIGN (<)
- Switch to the §8.2.4.32 Script data double escaped less-than sign state. Emit a U+003C LESS-THAN SIGN character token.
- U+0000 NULL
- parse error. Switch to the §8.2.4.29 Script data double escaped state. Emit a U+FFFD REPLACEMENT CHARACTER character token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Switch to the §8.2.4.29 Script data double escaped state. Emit the current input character as a character token.
8.2.4.31. Script data double escaped dash dash state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Emit a U+002D HYPHEN-MINUS character token.
- U+003C LESS-THAN SIGN (<)
- Switch to the §8.2.4.32 Script data double escaped less-than sign state. Emit a U+003C LESS-THAN SIGN character token.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.6 Script data state. Emit a U+003E GREATER-THAN SIGN character token.
- U+0000 NULL
- parse error. Switch to the §8.2.4.29 Script data double escaped state. Emit a U+FFFD REPLACEMENT CHARACTER character token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Switch to the §8.2.4.29 Script data double escaped state. Emit the current input character as a character token.
8.2.4.32. Script data double escaped less-than sign state
Consume the next input character:
- U+002F SOLIDUS (/)
- Set the temporary buffer to the empty string. Switch to the §8.2.4.33 Script data double escape end state. Emit a U+002F SOLIDUS character token.
- Anything else
- Switch to the §8.2.4.29 Script data double escaped state. Reconsume the current input character.
8.2.4.33. Script data double escape end state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+002F SOLIDUS (/)
- U+003E GREATER-THAN SIGN (>)
- U+000A LINE FEED (LF)
- If the temporary buffer is the string "
script
", then switch to the §8.2.4.22 Script data escaped state. Otherwise, switch to the §8.2.4.29 Script data double escaped state. Emit the current input character as a character token. - Uppercase ASCII letter
- Append the lowercase version of the current input character (add 0x0020 to the character’s code point) to the temporary buffer. Emit the current input character as a character token.
- Lowercase ASCII letter
- Append the current input character to the temporary buffer. Emit the current input character as a character token.
- Anything else
- Switch to the §8.2.4.29 Script data double escaped state. Reconsume the current input character.
8.2.4.34. Before attribute name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Ignore the character.
- U+002F SOLIDUS (/)
- Switch to the §8.2.4.43 Self-closing start tag state.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current tag token.
- Uppercase ASCII letter
- Start a new attribute in the current tag token. Set that attribute’s name to the lowercase version of the current input character (add 0x0020 to the character’s code point), and its value to the empty string. Switch to the §8.2.4.35 Attribute name state.
- U+0000 NULL
- parse error. Start a new attribute in the current tag token. Set that attribute’s name to a U+FFFD REPLACEMENT CHARACTER character, and its value to the empty string. Switch to the §8.2.4.35 Attribute name state.
- U+0022 QUOTATION MARK (")
- U+0027 APOSTROPHE (')
- U+003C LESS-THAN SIGN (<)
- U+003D EQUALS SIGN (=)
- U+0027 APOSTROPHE (')
- parse error. Treat it as per the "anything else" entry below.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Start a new attribute in the current tag token. Set that attribute’s name to the current input character, and its value to the empty string. Switch to the §8.2.4.35 Attribute name state.
8.2.4.35. Attribute name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Switch to the §8.2.4.36 After attribute name state.
- U+002F SOLIDUS (/)
- Switch to the §8.2.4.43 Self-closing start tag state.
- U+003D EQUALS SIGN (=)
- Switch to the §8.2.4.37 Before attribute value state.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current tag token.
- Uppercase ASCII letter
- Append the lowercase version of the current input character (add 0x0020 to the character’s code point) to the current attribute’s name.
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current attribute’s name.
- U+0022 QUOTATION MARK (")
- U+0027 APOSTROPHE (')
- U+003C LESS-THAN SIGN (<)
- U+0027 APOSTROPHE (')
- parse error. Treat it as per the "anything else" entry below.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Append the current input character to the current attribute’s name.
When the user agent leaves the attribute name state (and before emitting the tag token, if appropriate), the complete attribute’s name must be compared to the other attributes on the same token; if there is already an attribute on the token with the exact same name, then this is a parse error and the new attribute must be removed from the token.
If an attribute is so removed from a token, it, and the value that gets associated with it, if any, are never subsequently used by the parser, and are therefore effectively discarded. Removing the attribute in this way does not change its status as the "current attribute" for the purposes of the tokenizer, however.
8.2.4.36. After attribute name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Ignore the character.
- U+002F SOLIDUS (/)
- Switch to the §8.2.4.43 Self-closing start tag state.
- U+003D EQUALS SIGN (=)
- Switch to the §8.2.4.37 Before attribute value state.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current tag token.
- Uppercase ASCII letter
- Start a new attribute in the current tag token. Set that attribute’s name to the lowercase version of the current input character (add 0x0020 to the character’s code point), and its value to the empty string. Switch to the §8.2.4.35 Attribute name state.
- U+0000 NULL
- parse error. Start a new attribute in the current tag token. Set that attribute’s name to a U+FFFD REPLACEMENT CHARACTER character, and its value to the empty string. Switch to the §8.2.4.35 Attribute name state.
- U+0022 QUOTATION MARK (")
- U+0027 APOSTROPHE (')
- U+003C LESS-THAN SIGN (<)
- U+0027 APOSTROPHE (')
- parse error. Treat it as per the "anything else" entry below.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Start a new attribute in the current tag token. Set that attribute’s name to the current input character, and its value to the empty string. Switch to the §8.2.4.35 Attribute name state.
8.2.4.37. Before attribute value state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Ignore the character.
- U+0022 QUOTATION MARK (")
- Switch to the §8.2.4.38 Attribute value (double-quoted) state.
- U+0026 AMPERSAND (&)
- Switch to the §8.2.4.40 Attribute value (unquoted) state. Reconsume the current input character.
- U+0027 APOSTROPHE (')
- Switch to the §8.2.4.39 Attribute value (single-quoted) state.
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current attribute’s value. Switch to the §8.2.4.40 Attribute value (unquoted) state.
- U+003E GREATER-THAN SIGN (>)
- parse error. Switch to the §8.2.4.1 Data state. Emit the current tag token.
- U+003C LESS-THAN SIGN (<)
- U+003D EQUALS SIGN (=)
- U+0060 GRAVE ACCENT (`)
- U+003D EQUALS SIGN (=)
- parse error. Treat it as per the "anything else" entry below.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Append the current input character to the current attribute’s value. Switch to the §8.2.4.40 Attribute value (unquoted) state.
8.2.4.38. Attribute value (double-quoted) state
Consume the next input character:
- U+0022 QUOTATION MARK (")
- Switch to the §8.2.4.42 After attribute value (quoted) state.
- U+0026 AMPERSAND (&)
- Switch to the §8.2.4.41 Character reference in attribute value state, with the additional allowed character being U+0022 QUOTATION MARK (").
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current attribute’s value.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Append the current input character to the current attribute’s value.
8.2.4.39. Attribute value (single-quoted) state
Consume the next input character:
- U+0027 APOSTROPHE (')
- Switch to the §8.2.4.42 After attribute value (quoted) state.
- U+0026 AMPERSAND (&)
- Switch to the §8.2.4.41 Character reference in attribute value state, with the additional allowed character being U+0027 APOSTROPHE (').
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current attribute’s value.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Append the current input character to the current attribute’s value.
8.2.4.40. Attribute value (unquoted) state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Switch to the §8.2.4.34 Before attribute name state.
- U+0026 AMPERSAND (&)
- Switch to the §8.2.4.41 Character reference in attribute value state, with the additional allowed character being U+003E GREATER-THAN SIGN (>).
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current tag token.
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current attribute’s value.
- U+0022 QUOTATION MARK (")
- U+0027 APOSTROPHE (')
- U+003C LESS-THAN SIGN (<)
- U+003D EQUALS SIGN (=)
- U+0060 GRAVE ACCENT (`)
- U+0027 APOSTROPHE (')
- parse error. Treat it as per the "anything else" entry below.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- Append the current input character to the current attribute’s value.
8.2.4.41. Character reference in attribute value state
Attempt to consume a character reference.
If nothing is returned, append a U+0026 AMPERSAND character (&) to the current attribute’s value.
Otherwise, append the returned character tokens to the current attribute’s value.
Finally, switch back to the attribute value state that switched into this state.
8.2.4.42. After attribute value (quoted) state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Switch to the §8.2.4.34 Before attribute name state.
- U+002F SOLIDUS (/)
- Switch to the §8.2.4.43 Self-closing start tag state.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current tag token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- parse error. Switch to the §8.2.4.34 Before attribute name state. Reconsume the character.
8.2.4.43. Self-closing start tag state
Consume the next input character:
- U+003E GREATER-THAN SIGN (>)
- Set the self-closing flag of the current tag token. Switch to the §8.2.4.1 Data state. Emit the current tag token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Reconsume the EOF character.
- Anything else
- parse error. Switch to the §8.2.4.34 Before attribute name state. Reconsume the character.
8.2.4.44. Bogus comment state
Consume every character up to and including the first U+003E GREATER-THAN SIGN character (>)
or the end of the file (EOF), whichever comes first.
If more than one character was consumed, then emit a comment token whose data is the
concatenation of all the characters starting from and including the character that caused the
state machine to switch into the bogus comment state, up to and including the character
immediately before the last consumed character (i.e., up to the character just before the U+003E or
EOF character), but with any U+0000 NULL characters replaced by U+FFFD REPLACEMENT CHARACTER
characters. (If the comment was started by the end of the file (EOF), the token is empty.
Similarly, the token is empty if it was generated by the string "<!>
".)
Switch to the §8.2.4.1 Data state.
If the end of the file was reached, reconsume the EOF character.
8.2.4.45. Markup declaration open state
If the next two characters are both U+002D HYPHEN-MINUS characters (-), consume those two characters, create a comment token whose data is the empty string, and switch to the §8.2.4.46 Comment start state.
Otherwise, if the next seven characters are an ASCII case-insensitive match for the word "DOCTYPE", then consume those characters and switch to the §8.2.4.52 DOCTYPE state.
Otherwise, if there is an adjusted current node and it is not an element in the HTML namespace and the next seven characters are a case-sensitive match for the string "[CDATA[" (the five uppercase letters "CDATA" with a U+005B LEFT SQUARE BRACKET character before and after), then consume those characters and switch to the §8.2.4.68 CDATA section state.
Otherwise, this is a parse error. Switch to the §8.2.4.44 Bogus comment state. The next character that is consumed, if any, is the first character that will be in the comment.
8.2.4.46. Comment start state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Switch to the §8.2.4.47 Comment start dash state.
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the comment token’s data. Switch to the §8.2.4.48 Comment state.
- U+003E GREATER-THAN SIGN (>)
- parse error. Switch to the §8.2.4.1 Data state. Emit the comment token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Emit the comment token. Reconsume the EOF character.
- Anything else
- Append the current input character to the comment token’s data. Switch to the §8.2.4.48 Comment state.
8.2.4.47. Comment start dash state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Switch to the §8.2.4.50 Comment end state
- U+0000 NULL
- parse error. Append a U+002D HYPHEN-MINUS character (-) and a U+FFFD REPLACEMENT CHARACTER character to the comment token’s data. Switch to the §8.2.4.48 Comment state.
- U+003E GREATER-THAN SIGN (>)
- parse error. Switch to the §8.2.4.1 Data state. Emit the comment token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Emit the comment token. Reconsume the EOF character.
- Anything else
- Append a U+002D HYPHEN-MINUS character (-) and the current input character to the comment token’s data. Switch to the §8.2.4.48 Comment state.
8.2.4.48. Comment state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Switch to the §8.2.4.49 Comment end dash state
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the comment token’s data.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Emit the comment token. Reconsume the EOF character.
- Anything else
- Append the current input character to the comment token’s data.
8.2.4.49. Comment end dash state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Switch to the §8.2.4.50 Comment end state
- U+0000 NULL
- parse error. Append a U+002D HYPHEN-MINUS character (-) and a U+FFFD REPLACEMENT CHARACTER character to the comment token’s data. Switch to the §8.2.4.48 Comment state.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Emit the comment token. Reconsume the EOF character.
- Anything else
- Append a U+002D HYPHEN-MINUS character (-) and the current input character to the comment token’s data. Switch to the §8.2.4.48 Comment state.
8.2.4.50. Comment end state
Consume the next input character:
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the comment token.
- U+0000 NULL
- parse error. Append two U+002D HYPHEN-MINUS characters (-) and a U+FFFD REPLACEMENT CHARACTER character to the comment token’s data. Switch to the §8.2.4.48 Comment state.
- U+0021 EXCLAMATION MARK (!)
- parse error. Switch to the §8.2.4.51 Comment end bang state.
- U+002D HYPHEN-MINUS (-)
- parse error. Append a U+002D HYPHEN-MINUS character (-) to the comment token’s data.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Emit the comment token. Reconsume the EOF character.
- Anything else
- parse error. Append two U+002D HYPHEN-MINUS characters (-) and the current input character to the comment token’s data. Switch to the §8.2.4.48 Comment state.
8.2.4.51. Comment end bang state
Consume the next input character:
- U+002D HYPHEN-MINUS (-)
- Append two U+002D HYPHEN-MINUS characters (-) and a U+0021 EXCLAMATION MARK character (!) to the comment token’s data. Switch to the §8.2.4.49 Comment end dash state.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the comment token.
- U+0000 NULL
- parse error. Append two U+002D HYPHEN-MINUS characters (-), a U+0021 EXCLAMATION MARK character (!), and a U+FFFD REPLACEMENT CHARACTER character to the comment token’s data. Switch to the §8.2.4.48 Comment state.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Emit the comment token. Reconsume the EOF character.
- Anything else
- Append two U+002D HYPHEN-MINUS characters (-), a U+0021 EXCLAMATION MARK character (!), and the current input character to the comment token’s data. Switch to the §8.2.4.48 Comment state.
8.2.4.52. DOCTYPE state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Switch to the §8.2.4.53 Before DOCTYPE name state.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Create a new DOCTYPE token. Set its force-quirks flag to on. Emit the token. Reconsume the EOF character.
- Anything else
- parse error. Switch to the §8.2.4.53 Before DOCTYPE name state. Reconsume the character.
8.2.4.53. Before DOCTYPE name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Ignore the character.
- Uppercase ASCII letter
- Create a new DOCTYPE token. Set the token’s name to the lowercase version of the current input character (add 0x0020 to the character’s code point). Switch to the §8.2.4.54 DOCTYPE name state.
- U+0000 NULL
- parse error. Create a new DOCTYPE token. Set the token’s name to a U+FFFD REPLACEMENT CHARACTER character. Switch to the §8.2.4.54 DOCTYPE name state.
- U+003E GREATER-THAN SIGN (>)
- parse error. Create a new DOCTYPE token. Set its force-quirks flag to on. Switch to the §8.2.4.1 Data state. Emit the token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Create a new DOCTYPE token. Set its force-quirks flag to on. Emit the token. Reconsume the EOF character.
- Anything else
- Create a new DOCTYPE token. Set the token’s name to the current input character. Switch to the §8.2.4.54 DOCTYPE name state.
8.2.4.54. DOCTYPE name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Switch to the §8.2.4.55 After DOCTYPE name state.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current DOCTYPE token.
- Uppercase ASCII letter
- Append the lowercase version of the current input character (add 0x0020 to the character’s code point) to the current DOCTYPE token’s name.
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current DOCTYPE token’s name.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- Append the current input character to the current DOCTYPE token’s name.
8.2.4.55. After DOCTYPE name state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Ignore the character.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current DOCTYPE token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
-
If the six characters starting from the current input character are an ASCII case-insensitive match for the word "PUBLIC", then consume those characters and switch to the §8.2.4.56 After DOCTYPE public keyword state.
Otherwise, if the six characters starting from the current input character are an ASCII case-insensitive match for the word "SYSTEM", then consume those characters and switch to the §8.2.4.62 After DOCTYPE system keyword state.
Otherwise, this is a parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.67 Bogus DOCTYPE state.
8.2.4.56. After DOCTYPE public keyword state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Switch to the §8.2.4.57 Before DOCTYPE public identifier state.
- U+0022 QUOTATION MARK (")
- parse error. Set the DOCTYPE token’s public identifier to the empty string (not missing), then switch to the §8.2.4.58 DOCTYPE public identifier (double-quoted) state.
- U+0027 APOSTROPHE (')
- parse error. Set the DOCTYPE token’s public identifier to the empty string (not missing), then switch to the §8.2.4.59 DOCTYPE public identifier (single-quoted) state.
- U+003E GREATER-THAN SIGN (>)
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.1 Data state. Emit that DOCTYPE token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.67 Bogus DOCTYPE state.
8.2.4.57. Before DOCTYPE public identifier state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Ignore the character.
- U+0022 QUOTATION MARK (")
- Set the DOCTYPE token’s public identifier to the empty string (not missing), then switch to the §8.2.4.58 DOCTYPE public identifier (double-quoted) state.
- U+0027 APOSTROPHE (')
- Set the DOCTYPE token’s public identifier to the empty string (not missing), then switch to the §8.2.4.59 DOCTYPE public identifier (single-quoted) state.
- U+003E GREATER-THAN SIGN (>)
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.1 Data state. Emit that DOCTYPE token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.67 Bogus DOCTYPE state.
8.2.4.58. DOCTYPE public identifier (double-quoted) state
Consume the next input character:
- U+0022 QUOTATION MARK (")
- Switch to the §8.2.4.60 After DOCTYPE public identifier state.
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current DOCTYPE token’s public identifier.
- U+003E GREATER-THAN SIGN (>)
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.1 Data state. Emit that DOCTYPE token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- Append the current input character to the current DOCTYPE token’s public identifier.
8.2.4.59. DOCTYPE public identifier (single-quoted) state
Consume the next input character:
- U+0027 APOSTROPHE (')
- Switch to the §8.2.4.60 After DOCTYPE public identifier state.
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current DOCTYPE token’s public identifier.
- U+003E GREATER-THAN SIGN (>)
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.1 Data state. Emit that DOCTYPE token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- Append the current input character to the current DOCTYPE token’s public identifier.
8.2.4.60. After DOCTYPE public identifier state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Switch to the §8.2.4.61 Between DOCTYPE public and system identifiers state.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current DOCTYPE token.
- U+0022 QUOTATION MARK (")
- parse error. Set the DOCTYPE token’s system identifier to the empty string (not missing), then switch to the §8.2.4.64 DOCTYPE system identifier (double-quoted) state.
- U+0027 APOSTROPHE (')
- parse error. Set the DOCTYPE token’s system identifier to the empty string (not missing), then switch to the §8.2.4.65 DOCTYPE system identifier (single-quoted) state.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.67 Bogus DOCTYPE state.
8.2.4.61. Between DOCTYPE public and system identifiers state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Ignore the character.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current DOCTYPE token.
- U+0022 QUOTATION MARK (")
- Set the DOCTYPE token’s system identifier to the empty string (not missing), then switch to the §8.2.4.64 DOCTYPE system identifier (double-quoted) state.
- U+0027 APOSTROPHE (')
- Set the DOCTYPE token’s system identifier to the empty string (not missing), then switch to the §8.2.4.65 DOCTYPE system identifier (single-quoted) state.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.67 Bogus DOCTYPE state.
8.2.4.62. After DOCTYPE system keyword state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Switch to the §8.2.4.63 Before DOCTYPE system identifier state.
- U+0022 QUOTATION MARK (")
- parse error. Set the DOCTYPE token’s system identifier to the empty string (not missing), then switch to the §8.2.4.64 DOCTYPE system identifier (double-quoted) state.
- U+0027 APOSTROPHE (')
- parse error. Set the DOCTYPE token’s system identifier to the empty string (not missing), then switch to the §8.2.4.65 DOCTYPE system identifier (single-quoted) state.
- U+003E GREATER-THAN SIGN (>)
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.1 Data state. Emit that DOCTYPE token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.67 Bogus DOCTYPE state.
8.2.4.63. Before DOCTYPE system identifier state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Ignore the character.
- U+0022 QUOTATION MARK (")
- Set the DOCTYPE token’s system identifier to the empty string (not missing), then switch to the §8.2.4.64 DOCTYPE system identifier (double-quoted) state.
- U+0027 APOSTROPHE (')
- Set the DOCTYPE token’s system identifier to the empty string (not missing), then switch to the §8.2.4.65 DOCTYPE system identifier (single-quoted) state.
- U+003E GREATER-THAN SIGN (>)
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.1 Data state. Emit that DOCTYPE token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.67 Bogus DOCTYPE state.
8.2.4.64. DOCTYPE system identifier (double-quoted) state
Consume the next input character:
- U+0022 QUOTATION MARK (")
- Switch to the §8.2.4.66 After DOCTYPE system identifier state.
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current DOCTYPE token’s system identifier.
- U+003E GREATER-THAN SIGN (>)
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.1 Data state. Emit that DOCTYPE token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- Append the current input character to the current DOCTYPE token’s system identifier.
8.2.4.65. DOCTYPE system identifier (single-quoted) state
Consume the next input character:
- U+0027 APOSTROPHE (')
- Switch to the §8.2.4.66 After DOCTYPE system identifier state.
- U+0000 NULL
- parse error. Append a U+FFFD REPLACEMENT CHARACTER character to the current DOCTYPE token’s system identifier.
- U+003E GREATER-THAN SIGN (>)
- parse error. Set the DOCTYPE token’s force-quirks flag to on. Switch to the §8.2.4.1 Data state. Emit that DOCTYPE token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- Append the current input character to the current DOCTYPE token’s system identifier.
8.2.4.66. After DOCTYPE system identifier state
Consume the next input character:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+000A LINE FEED (LF)
- Ignore the character.
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the current DOCTYPE token.
- EOF
- parse error. Switch to the §8.2.4.1 Data state. Set the DOCTYPE token’s force-quirks flag to on. Emit that DOCTYPE token. Reconsume the EOF character.
- Anything else
- parse error. Switch to the §8.2.4.67 Bogus DOCTYPE state. (This does not set the DOCTYPE token’s force-quirks flag to on.)
8.2.4.67. Bogus DOCTYPE state
Consume the next input character:
- U+003E GREATER-THAN SIGN (>)
- Switch to the §8.2.4.1 Data state. Emit the DOCTYPE token.
- EOF
- Switch to the §8.2.4.1 Data state. Emit the DOCTYPE token. Reconsume the EOF character.
- Anything else
- Ignore the character.
8.2.4.68. CDATA section state
Switch to the §8.2.4.1 Data state.
Consume every character up to the next occurrence of the three character sequence U+005D RIGHT
SQUARE BRACKET U+005D RIGHT SQUARE BRACKET U+003E GREATER-THAN SIGN (]]>
),
or the end of the file (EOF), whichever comes first. Emit a series of character tokens consisting
of all the characters consumed except the matching three character sequence at the end (if one was
found before the end of the file).
If the end of the file was reached, reconsume the EOF character.
8.2.4.69. Tokenizing character references
This section defines how to consume a character reference, optionally with an additional allowed character, which, if specified where the algorithm is invoked, adds a character to the list of characters that cause there to not be a character reference.
This definition is used when parsing character references in text and in attributes.
The behavior depends on the identity of the next character (the one immediately after the U+0026 AMPERSAND character), as follows:
- U+0009 CHARACTER TABULATION (tab)
- U+000A LINE FEED (LF)
- U+000C FORM FEED (FF)
- U+0020 SPACE
- U+003C LESS-THAN SIGN
- U+0026 AMPERSAND
- EOF
- The additional allowed character, if there is one
- U+000A LINE FEED (LF)
- Not a character reference. No characters are consumed, and nothing is returned. (This is not an error, either.)
- U+0023 NUMBER SIGN (#)
-
Consume the U+0023 NUMBER SIGN.
The behavior further depends on the character after the U+0023 NUMBER SIGN:
- U+0078 LATIN SMALL LETTER X
- U+0058 LATIN CAPITAL LETTER X
-
Consume the X.
Follow the steps below, but using ASCII hex digits.
When it comes to interpreting the number, interpret it as a hexadecimal number.
- Anything else
-
Follow the steps below, but using ASCII digits.
When it comes to interpreting the number, interpret it as a decimal number.
Consume as many characters as match the range of characters given above (ASCII hex digits or ASCII digits).
If no characters match the range, then don’t consume any characters (and unconsume the U+0023 NUMBER SIGN character and, if appropriate, the X character). This is a parse error; nothing is returned.
Otherwise, if the next character is a U+003B SEMICOLON, consume that too. If it isn’t, there is a parse error.
If one or more characters match the range, then take them all and interpret the string of characters as a number (either hexadecimal or decimal as appropriate).
If that number is one of the numbers in the first column of the following table, then this is a parse error. Find the row with that number in the first column, and return a character token for the Unicode character given in the second column of that row.
Number Unicode character 0x00 U+FFFD REPLACEMENT CHARACTER 0x80 U+20AC EURO SIGN (€) 0x82 U+201A SINGLE LOW-9 QUOTATION MARK (‚) 0x83 U+0192 LATIN SMALL LETTER F WITH HOOK (ƒ) 0x84 U+201E DOUBLE LOW-9 QUOTATION MARK („) 0x85 U+2026 HORIZONTAL ELLIPSIS (…) 0x86 U+2020 DAGGER (†) 0x87 U+2021 DOUBLE DAGGER (‡) 0x88 U+02C6 MODIFIER LETTER CIRCUMFLEX ACCENT (ˆ) 0x89 U+2030 PER MILLE SIGN (‰) 0x8A U+0160 LATIN CAPITAL LETTER S WITH CARON (Š) 0x8B U+2039 SINGLE LEFT-POINTING ANGLE QUOTATION MARK (‹) 0x8C U+0152 LATIN CAPITAL LIGATURE OE (Œ) 0x8E U+017D LATIN CAPITAL LETTER Z WITH CARON (Ž) 0x91 U+2018 LEFT SINGLE QUOTATION MARK (‘) 0x92 U+2019 RIGHT SINGLE QUOTATION MARK (’) 0x93 U+201C LEFT DOUBLE QUOTATION MARK (“) 0x94 U+201D RIGHT DOUBLE QUOTATION MARK (”) 0x95 U+2022 BULLET (•) 0x96 U+2013 EN DASH (–) 0x97 U+2014 EM DASH (—) 0x98 U+02DC SMALL TILDE (˜) 0x99 U+2122 TRADE MARK SIGN (™) 0x9A U+0161 LATIN SMALL LETTER S WITH CARON (š) 0x9B U+203A SINGLE RIGHT-POINTING ANGLE QUOTATION MARK (›) 0x9C U+0153 LATIN SMALL LIGATURE OE (œ) 0x9E U+017E LATIN SMALL LETTER Z WITH CARON (ž) 0x9F U+0178 LATIN CAPITAL LETTER Y WITH DIAERESIS (Ÿ) Otherwise, if the number is in the range 0xD800 to 0xDFFF or is greater than 0x10FFFF, then this is a parse error. Return a U+FFFD REPLACEMENT CHARACTER character token.
Otherwise, return a character token for the Unicode character whose code point is that number.
Additionally, if the number is in the range 0x0001 to 0x0008, 0x000D to 0x001F, 0x007F to 0x009F, 0xFDD0 to 0xFDEF, or is one of 0x000B, 0xFFFE, 0xFFFF, 0x1FFFE, 0x1FFFF, 0x2FFFE, 0x2FFFF, 0x3FFFE, 0x3FFFF, 0x4FFFE, 0x4FFFF, 0x5FFFE, 0x5FFFF, 0x6FFFE, 0x6FFFF, 0x7FFFE, 0x7FFFF, 0x8FFFE, 0x8FFFF, 0x9FFFE, 0x9FFFF, 0xAFFFE, 0xAFFFF, 0xBFFFE, 0xBFFFF, 0xCFFFE, 0xCFFFF, 0xDFFFE, 0xDFFFF, 0xEFFFE, 0xEFFFF, 0xFFFFE, 0xFFFFF, 0x10FFFE, or 0x10FFFF, then this is a parse error.
- U+0078 LATIN SMALL LETTER X
- Anything else
-
Consume the maximum number of characters possible, with the consumed characters matching one of the identifiers in the first column of the §8.5 Named character references table (in a case-sensitive manner).
If no match can be made, then no characters are consumed, and nothing is returned. In this case, if the characters after the U+0026 AMPERSAND character (&) consist of a sequence of one or more alphanumeric ASCII characters followed by a U+003B SEMICOLON character (;), then this is a parse error.
If the character reference is being consumed as part of an attribute, and the last character matched is not a U+003B SEMICOLON character (;), and the next character is either a U+003D EQUALS SIGN character (=) or an alphanumeric ASCII character, then, for historical reasons, all the characters that were matched after the U+0026 AMPERSAND character (&) must be unconsumed, and nothing is returned.
However, if this next character is in fact a U+003D EQUALS SIGN character (=), then this is a parse error, because some legacy user agents will misinterpret the markup in those cases.
Otherwise, a character reference is parsed. If the last character matched is not a U+003B SEMICOLON character (;), there is a parse error.
Return one or two character tokens for the character(s) corresponding to the character reference name (as given by the second column of the §8.5 Named character references table).
If the markup contains (not in an attribute) the stringI’m ¬it; I tell you
, the character reference is parsed as "not", as in,I’m ¬it; I tell you
(and this is a parse error). But if the markup wasI’m ∉ I tell you
, the character reference would be parsed as "notin;", resulting inI’m ∉ I tell you
(and no parse error).
8.2.5. Tree construction
The input to the tree construction stage is a sequence of tokens from the tokenization stage. The tree construction stage is associated with a DOM Document
object when a parser is created. The "output" of this stage consists of
dynamically modifying or extending that document’s DOM tree.
This specification does not define when an interactive user agent has to render the Document
so that it is available to the user, or when it has to begin accepting user
input.
As each token is emitted from the tokenizer, the user agent must follow the appropriate steps from the following list, known as the tree construction dispatcher:
- If the stack of open elements is empty
- If the adjusted current node is an element in the HTML namespace
- If the adjusted current node is a MathML text integration point and the token is a start tag whose tag name is neither "mglyph" nor "malignmark"
- If the adjusted current node is a MathML text integration point and the token is a character token
- If the adjusted current node is an
annotation-xml
element in the MathML namespace and the token is a start tag whose tag name is "svg"- If the adjusted current node is an HTML integration point and the token is a start tag
- If the adjusted current node is an HTML integration point and the token is a character token
- If the token is an end-of-file token
- If the adjusted current node is an element in the HTML namespace
- Process the token according to the rules given in the section corresponding to the current insertion mode in HTML content.
- Otherwise
- Process the token according to the rules given in the section for parsing tokens in foreign content.
The next token is the token that is about to be processed by the tree construction dispatcher (even if the token is subsequently just ignored).
A node is a MathML text integration point if it is one of the following elements:
- An
mi
element in the MathML namespace - An
mo
element in the MathML namespace - An
mn
element in the MathML namespace - An
ms
element in the MathML namespace - An
mtext
element in the MathML namespace
A node is an HTML integration point if it is one of the following elements:
- An
annotation-xml
element in the MathML namespace whose start tag token had an attribute with the name "encoding" whose value was an ASCII case-insensitive match for the string "text/html
" - An
annotation-xml
element in the MathML namespace whose start tag token had an attribute with the name "encoding" whose value was an ASCII case-insensitive match for the string "application/xhtml+xml
" - A
foreignObject
element in the SVG namespace - A
desc
element in the SVG namespace - A
title
element in the SVG namespace
If the node in question is the context element passed to the HTML fragment parsing algorithm, then the start tag token for that element is the "fake" token created during by that HTML fragment parsing algorithm.
Not all of the tag names mentioned below are conformant tag names in this specification; many are included to handle legacy content. They still form part of the algorithm that implementations are required to implement to claim conformance.
The algorithm described below places no limit on the depth of the DOM tree
generated, or on the length of tag names, attribute names, attribute values, Text
nodes, etc. While implementors are encouraged to avoid arbitrary limits, it is recognized that practical concerns will likely force user agents to impose nesting
depth constraints.
8.2.5.1. Creating and inserting nodes
While the parser is processing a token, it can enable or disable foster parenting. This affects the following algorithm.
The appropriate place for inserting a node, optionally using a particular override target, is the position in an element returned by running the following steps:
-
If there was an override target specified, then let target be the override target.
Otherwise, let target be the current node.
-
Determine the adjusted insertion location using the first matching steps from the following list:
- If foster parenting is enabled and target is a
table
,tbody
,tfoot
,thead
, ortr
element -
Foster parenting happens when content is misnested in tables.
Run these substeps:
- Let last template be the last
template
element in the stack of open elements, if any. - Let last table be the last
table
element in the stack of open elements, if any. - If there is a last template and either there is no last table, or there is one, but last template is lower (more recently added) than last table in the stack of open elements, then: let adjusted insertion location be inside last template’s template contents, after its last child (if any), and abort these substeps.
- If there is no last table, then let adjusted insertion
location be inside the first element in the stack of open elements (the
html
element), after its last child (if any), and abort these substeps. (fragment case) - If last table has a parent node, then let adjusted insertion location be inside last table’s parent node, immediately before last table, and abort these substeps.
- Let previous element be the element immediately above last table in the stack of open elements.
- Let adjusted insertion location be inside previous element, after its last child (if any).
These steps are involved in part because it’s possible for elements, the
table
element in this case in particular, to have been moved by a script around in the DOM, or indeed removed from the DOM entirely, after the element was inserted by the parser. - Let last template be the last
- Otherwise
-
Let adjusted insertion location be inside target, after its last child (if any).
- If foster parenting is enabled and target is a
-
If the adjusted insertion location is inside a
template
element, let it instead be inside thetemplate
element’s template contents, after its last child (if any). -
Return the adjusted insertion location.
When the steps below require the user agent to create an element for a token in a particular given namespace and with a particular intended parent, the user agent must run the following steps:
-
Create a node implementing the interface appropriate for the element type corresponding to the tag name of the token in given namespace (as given in the specification that defines that element, e.g., for an
a
element in the HTML namespace, this specification defines it to be theHTMLAnchorElement
interface), with the tag name being the name of that element, with the node being in the given namespace, and with the attributes on the node being those given in the given token.The interface appropriate for an element in the HTML namespace that is not defined in this specification (or other applicable specifications) is
HTMLUnknownElement
. Elements in other namespaces whose interface is not defined by that namespace’s specification must use the interfaceElement
.The node document of the newly created element must be the node document of the intended parent.
- If the newly created element has an
xmlns
attribute in the XMLNS namespace whose value is not exactly the same as the element’s namespace, that is a parse error. Similarly, if the newly created element has anxmlns:xlink
attribute in the XMLNS namespace whose value is not the XLink namespace, that is a parse error. - If the newly created element is a resettable element, invoke its reset algorithm. (This initializes the element’s value and checkedness based on the element’s attributes.)
- If the element is a form-associated element, and the
form
element pointer is not null, and there is notemplate
element on the stack of open elements, and the newly created element is either not reassociateable or doesn’t have aform
attribute, and the intended parent is in the same home subtree as the element pointed to by theform
element pointer, associate the newly created element with theform
element pointed to by theform
element pointer, and suppress the running of the reset the form owner algorithm when the parser subsequently attempts to insert the element. - Return the newly created element.
When the steps below require the user agent to insert a foreign element for a token in a given namespace, the user agent must run these steps:
- Let the adjusted insertion location be the appropriate place for inserting a node.
- Create an element for the token in the given namespace, with the intended parent being the element in which the adjusted insertion location finds itself.
-
If it is possible to insert an element at the adjusted insertion location, then insert the newly created element at the adjusted insertion location.
If the adjusted insertion location cannot accept more elements, e.g., because it’s a
Document
that already has an element child, then the newly created element is dropped on the floor. - Push the element onto the stack of open elements so that it is the new current node.
- Return the newly created element.
When the steps below require the user agent to insert an HTML element for a token, the user agent must insert a foreign element for the token, in the HTML namespace.
When the steps below require the user agent to adjust MathML attributes for a token,
then, if the token has an attribute named definitionurl
, change its name to definitionURL
(note the case difference).
When the steps below require the user agent to adjust SVG attributes for a token, then, for each attribute on the token whose attribute name is one of the ones in the first column of the following table, change the attribute’s name to the name given in the corresponding cell in the second column. (This fixes the case of SVG attributes that are not all lowercase.)
Attribute name on token | Attribute name on element |
---|---|
attributename
| attributeName
|
attributetype
| attributeType
|
basefrequency
| baseFrequency
|
baseprofile
| baseProfile
|
calcmode
| calcMode
|
clippathunits
| clipPathUnits
|
diffuseconstant
| diffuseConstant
|
edgemode
| edgeMode
|
filterunits
| filterUnits
|
glyphref
| glyphRef
|
gradienttransform
| gradientTransform
|
gradientunits
| gradientUnits
|
kernelmatrix
| kernelMatrix
|
kernelunitlength
| kernelUnitLength
|
keypoints
| keyPoints
|
keysplines
| keySplines
|
keytimes
| keyTimes
|
lengthadjust
| lengthAdjust
|
limitingconeangle
| limitingConeAngle
|
markerheight
| markerHeight
|
markerunits
| markerUnits
|
markerwidth
| markerWidth
|
maskcontentunits
| maskContentUnits
|
maskunits
| maskUnits
|
numoctaves
| numOctaves
|
pathlength
| pathLength
|
patterncontentunits
| patternContentUnits
|
patterntransform
| patternTransform
|
patternunits
| patternUnits
|
pointsatx
| pointsAtX
|
pointsaty
| pointsAtY
|
pointsatz
| pointsAtZ
|
preservealpha
| preserveAlpha
|
preserveaspectratio
| preserveAspectRatio
|
primitiveunits
| primitiveUnits
|
refx
| refX
|
refy
| refY
|
repeatcount
| repeatCount
|
repeatdur
| repeatDur
|
requiredextensions
| requiredExtensions
|
requiredfeatures
| requiredFeatures
|
specularconstant
| specularConstant
|
specularexponent
| specularExponent
|
spreadmethod
| spreadMethod
|
startoffset
| startOffset
|
stddeviation
| stdDeviation
|
stitchtiles
| stitchTiles
|
surfacescale
| surfaceScale
|
systemlanguage
| systemLanguage
|
tablevalues
| tableValues
|
targetx
| targetX
|
targety
| targetY
|
textlength
| textLength
|
viewbox
| viewBox
|
viewtarget
| viewTarget
|
xchannelselector
| xChannelSelector
|
ychannelselector
| yChannelSelector
|
zoomandpan
| zoomAndPan
|
When the steps below require the user agent to adjust foreign attributes for a
token, then, if any of the attributes on the token match the strings given in the first column of
the following table, let the attribute be a namespaced attribute, with the prefix being the string
given in the corresponding cell in the second column, the local name being the string given in the
corresponding cell in the third column, and the namespace being the namespace given in the
corresponding cell in the fourth column. (This fixes the use of namespaced attributes, in
particular lang
attributes in the XML namespace.)
Attribute name | Prefix | Local name | Namespace |
---|---|---|---|
xlink:actuate
| xlink
| actuate
| XLink namespace |
xlink:arcrole
| xlink
| arcrole
| XLink namespace |
xlink:href
| xlink
| href
| XLink namespace |
xlink:role
| xlink
| role
| XLink namespace |
xlink:show
| xlink
| show
| XLink namespace |
xlink:title
| xlink
| title
| XLink namespace |
xlink:type
| xlink
| type
| XLink namespace |
xml:lang
| xml
| lang
| XML namespace |
xml:space
| xml
| space
| XML namespace |
xmlns
| (none) | xmlns
| XMLNS namespace |
xmlns:xlink
| xmlns
| xlink
| XMLNS namespace |
When the steps below require the user agent to insert a character while processing a token, the user agent must run the following steps:
- Let data be the characters passed to the algorithm, or, if no characters were explicitly specified, the character of the character token being processed.
- Let the adjusted insertion location be the appropriate place for inserting a node.
-
If the adjusted insertion location is in a
Document
node, then abort these steps.The DOM will not let
Document
nodes haveText
node children, so they are dropped on the floor. -
If there is a
Text
node immediately before the adjusted insertion location, then append data to thatText
node’s data.Otherwise, create a new
Text
node whose data is data and whose node document is the same as that of the element in which the adjusted insertion location finds itself, and insert the newly created node at the adjusted insertion location.
Text
nodes that they result in, assuming a user agent that executes scripts.
Input | Number of Text nodes
|
---|---|
A<script> var script = document.getElementsByTagName('script')[0]; document.body.removeChild(script); </script>B | One Text node in the document, containing "AB".
|
A<script> var text = document.createTextNode('B'); document.body.appendChild(text); </script>C | Three Text nodes; "A" before the script, the script’s contents, and "BC" after the script (the parser appends to the Text node created by the script).
|
A<script> var text = document.getElementsByTagName('script')[0].firstChild; text.data = 'B'; document.body.appendChild(text); </script>C | Two adjacent Text nodes in the document, containing "A" and "BC".
|
A<table>B<tr>C</tr>D</table> | One Text node before the table, containing "ABCD". (This is caused by foster parenting.)
|
A<table><tr> B</tr> C</table> | One Text node before the table, containing "A B C" (A-space-B-space-C). (This is caused by foster parenting.)
|
A<table><tr> B</tr> </em>C</table> | One Text node before the table, containing "A BC" (A-space-B-C), and one Text node inside the table (as a child of a tbody ) with a single space character. (Space characters separated from non-space characters by non-character tokens are not affected by foster parenting, even if those other tokens then get ignored.)
|
When the steps below require the user agent to insert a comment while processing a comment token, optionally with an explicitly insertion position position, the user agent must run the following steps:
- Let data be the data given in the comment token being processed.
- If position was specified, then let the adjusted insertion location be position. Otherwise, let adjusted insertion location be the appropriate place for inserting a node.
- Create a
Comment
node whosedata
attribute is set to data and whose node document is the same as that of the node in which the adjusted insertion location finds itself. - Insert the newly created node at the adjusted insertion location.
DOM mutation events must not fire for changes caused by the user agent
parsing the document. This includes the parsing of any content inserted using document.write()
and document.writeln()
calls. [UIEVENTS]
However, mutation observers do fire, as required by the DOM specification.
8.2.5.2. Parsing elements that contain only text
The generic raw text element parsing algorithm and the generic RCDATA element parsing algorithm consist of the following steps. These algorithms are always invoked in response to a start tag token.
- Insert an HTML element for the token.
- If the algorithm that was invoked is the generic raw text element parsing algorithm, switch the tokenizer to the §8.2.4.5 RAWTEXT state; otherwise the algorithm invoked was the generic RCDATA element parsing algorithm, switch the tokenizer to the §8.2.4.3 RCDATA state.
- Let the original insertion mode be the current insertion mode.
- Then, switch the insertion mode to "text".
8.2.5.3. Closing elements that have implied end tags
When the steps below require the user agent to generate implied end
tags, then, while the current node is a dd
element, a dt
element, an li
element, an option
element, an optgroup
element, a p
element, an rb
element, an rp
element, an rt
element, or an rtc
element, the user agent must
pop the current node off the stack of open
elements.
If a step requires the user agent to generate implied end tags but lists an element to exclude from the process, then the user agent must perform the above steps as if that element was not in the above list.
When the steps below require the user agent to generate all implied end tags thoroughly,
then, while the current node is a caption
element, a colgroup
element, a dd
element, a dt
element, an li
element, an optgroup
element, an option
element, a p
element, an rb
element, an rp
element, an rt
element, an rtc
element, a tbody
element, a td
element, a tfoot
element, a th
element, a thead
element, or a tr
element, the user agent must pop the current node off the stack of open elements.
8.2.5.4. The rules for parsing tokens in HTML content
8.2.5.4.1. The "initial" insertion mode
When the user agent is to apply the rules for the "initial" insertion mode, the user agent must handle the token as follows:
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- Ignore the token.
- A comment token
- Insert a comment as the last child of the
Document
object. - A DOCTYPE token
-
If the DOCTYPE token’s name is not a case-sensitive match for the string "
html
", or the token’s public identifier is not missing, or the token’s system identifier is neither missing nor a case-sensitive match for the string "about:legacy-compat
", and none of the sets of conditions in the following list are matched, then there is a parse error.- The DOCTYPE token’s name is a case-sensitive match for the string "
html
", the token’s public identifier is the case-sensitive string "-//W3C//DTD HTML 4.0//EN
", and the token’s system identifier is either missing or the case-sensitive string "https://www.w3.org/TR/REC-html40/strict.dtd
". - The DOCTYPE token’s name is a case-sensitive match for the string "
html
", the token’s public identifier is the case-sensitive string "-//W3C//DTD HTML 4.01//EN
", and the token’s system identifier is either missing or the case-sensitive string "https://www.w3.org/TR/html4/strict.dtd
". - The DOCTYPE token’s name is a case-sensitive match for the string "
html
", the token’s public identifier is the case-sensitive string "-//W3C//DTD XHTML 1.0 Strict//EN
", and the token’s system identifier is the case-sensitive string "https://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd
". - The DOCTYPE token’s name is a case-sensitive match for the string "
html
", the token’s public identifier is the case-sensitive string "-//W3C//DTD XHTML 1.1//EN
", and the token’s system identifier is the case-sensitive string "https://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd
".
Conformance checkers may, based on the values (including presence or lack thereof) of the DOCTYPE token’s name, public identifier, or system identifier, switch to a conformance checking mode for another language (e.g., based on the DOCTYPE token a conformance checker could recognize that the document is an HTML 4.01-era document, and defer to an HTML 4.01 conformance checker.)
Append a
DocumentType
node to theDocument
node, with thename
attribute set to the name given in the DOCTYPE token, or the empty string if the name was missing; thepublicId
attribute set to the public identifier given in the DOCTYPE token, or the empty string if the public identifier was missing; thesystemId
attribute set to the system identifier given in the DOCTYPE token, or the empty string if the system identifier was missing; and the other attributes specific toDocumentType
objects set to null and empty lists as appropriate. Associate theDocumentType
node with theDocument
object so that it is returned as the value of thedoctype
attribute of theDocument
object.Then, if the document is not an
iframe
srcdoc
document, and the DOCTYPE token matches one of the conditions in the following list, then set theDocument
to quirks mode:- The force-quirks flag is set to on.
- The name is set to anything other than "
html
" (compared case-sensitively). - The public identifier is set to: "
-//W3O//DTD W3 HTML Strict 3.0//EN//
" - The public identifier is set to: "
-/W3C/DTD HTML 4.0 Transitional/EN
" - The public identifier is set to: "
HTML
" - The system identifier is set to: "
https://www.ibm.com/data/dtd/v11/ibmxhtml1-transitional.dtd
" - The public identifier starts with: "
+//Silmaril//dtd html Pro v0r11 19970101//
" - The public identifier starts with: "
-//AS//DTD HTML 3.0 asWedit + extensions//
" - The public identifier starts with: "
-//AdvaSoft Ltd//DTD HTML 3.0 asWedit + extensions//
" - The public identifier starts with: "
-//IETF//DTD HTML 2.0 Level 1//
" - The public identifier starts with: "
-//IETF//DTD HTML 2.0 Level 2//
" - The public identifier starts with: "
-//IETF//DTD HTML 2.0 Strict Level 1//
" - The public identifier starts with: "
-//IETF//DTD HTML 2.0 Strict Level 2//
" - The public identifier starts with: "
-//IETF//DTD HTML 2.0 Strict//
" - The public identifier starts with: "
-//IETF//DTD HTML 2.0//
" - The public identifier starts with: "
-//IETF//DTD HTML 2.1E//
" - The public identifier starts with: "
-//IETF//DTD HTML 3.0//
" - The public identifier starts with: "
-//IETF//DTD HTML 3.2 Final//
" - The public identifier starts with: "
-//IETF//DTD HTML 3.2//
" - The public identifier starts with: "
-//IETF//DTD HTML 3//
" - The public identifier starts with: "
-//IETF//DTD HTML Level 0//
" - The public identifier starts with: "
-//IETF//DTD HTML Level 1//
" - The public identifier starts with: "
-//IETF//DTD HTML Level 2//
" - The public identifier starts with: "
-//IETF//DTD HTML Level 3//
" - The public identifier starts with: "
-//IETF//DTD HTML Strict Level 0//
" - The public identifier starts with: "
-//IETF//DTD HTML Strict Level 1//
" - The public identifier starts with: "
-//IETF//DTD HTML Strict Level 2//
" - The public identifier starts with: "
-//IETF//DTD HTML Strict Level 3//
" - The public identifier starts with: "
-//IETF//DTD HTML Strict//
" - The public identifier starts with: "
-//IETF//DTD HTML//
" - The public identifier starts with: "
-//Metrius//DTD Metrius Presentational//
" - The public identifier starts with: "
-//Microsoft//DTD Internet Explorer 2.0 HTML Strict//
" - The public identifier starts with: "
-//Microsoft//DTD Internet Explorer 2.0 HTML//
" - The public identifier starts with: "
-//Microsoft//DTD Internet Explorer 2.0 Tables//
" - The public identifier starts with: "
-//Microsoft//DTD Internet Explorer 3.0 HTML Strict//
" - The public identifier starts with: "
-//Microsoft//DTD Internet Explorer 3.0 HTML//
" - The public identifier starts with: "
-//Microsoft//DTD Internet Explorer 3.0 Tables//
" - The public identifier starts with: "
-//Netscape Comm. Corp.//DTD HTML//
" - The public identifier starts with: "
-//Netscape Comm. Corp.//DTD Strict HTML//
" - The public identifier starts with: "
-//O’Reilly and Associates//DTD HTML 2.0//
" - The public identifier starts with: "
-//O’Reilly and Associates//DTD HTML Extended 1.0//
" - The public identifier starts with: "
-//O’Reilly and Associates//DTD HTML Extended Relaxed 1.0//
" - The public identifier starts with: "
-//SQ//DTD HTML 2.0 HoTMetaL + extensions//
" - The public identifier starts with: "
-//SoftQuad Software//DTD HoTMetaL PRO 6.0::19990601::extensions to HTML 4.0//
" - The public identifier starts with: "
-//SoftQuad//DTD HoTMetaL PRO 4.0::19971010::extensions to HTML 4.0//
" - The public identifier starts with: "
-//Spyglass//DTD HTML 2.0 Extended//
" - The public identifier starts with: "
-//Sun Microsystems Corp.//DTD HotJava HTML//
" - The public identifier starts with: "
-//Sun Microsystems Corp.//DTD HotJava Strict HTML//
" - The public identifier starts with: "
-//W3C//DTD HTML 3 1995-03-24//
" - The public identifier starts with: "
-//W3C//DTD HTML 3.2 Draft//
" - The public identifier starts with: "
-//W3C//DTD HTML 3.2 Final//
" - The public identifier starts with: "
-//W3C//DTD HTML 3.2//
" - The public identifier starts with: "
-//W3C//DTD HTML 3.2S Draft//
" - The public identifier starts with: "
-//W3C//DTD HTML 4.0 Frameset//
" - The public identifier starts with: "
-//W3C//DTD HTML 4.0 Transitional//
" - The public identifier starts with: "
-//W3C//DTD HTML Experimental 19960712//
" - The public identifier starts with: "
-//W3C//DTD HTML Experimental 970421//
" - The public identifier starts with: "
-//W3C//DTD W3 HTML//
" - The public identifier starts with: "
-//W3O//DTD W3 HTML 3.0//
" - The public identifier starts with: "
-//WebTechs//DTD Mozilla HTML 2.0//
" - The public identifier starts with: "
-//WebTechs//DTD Mozilla HTML//
" - The system identifier is missing and the public identifier starts with: "
-//W3C//DTD HTML 4.01 Frameset//
" - The system identifier is missing and the public identifier starts with: "
-//W3C//DTD HTML 4.01 Transitional//
"
Otherwise, if the document is not an
iframe
srcdoc
document, and the DOCTYPE token matches one of the conditions in the following list, then set theDocument
to limited-quirks mode:- The public identifier starts with: "
-//W3C//DTD XHTML 1.0 Frameset//
" - The public identifier starts with: "
-//W3C//DTD XHTML 1.0 Transitional//
" - The system identifier is not missing and the public identifier starts with: "
-//W3C//DTD HTML 4.01 Frameset//
" - The system identifier is not missing and the public identifier starts with: "
-//W3C//DTD HTML 4.01 Transitional//
"
The system identifier and public identifier strings must be compared to the values given in the lists above in an ASCII case-insensitive manner. A system identifier whose value is the empty string is not considered missing for the purposes of the conditions above.
Then, switch the insertion mode to "before html".
- The DOCTYPE token’s name is a case-sensitive match for the string "
- Anything else
-
If the document is not an
iframe
srcdoc
document, then this is a parse error; set theDocument
to quirks mode.In any case, switch the insertion mode to "before html", then reprocess the token.
8.2.5.4.2. The "before html" insertion mode
When the user agent is to apply the rules for the "before html" insertion mode, the user agent must handle the token as follows:
- A DOCTYPE token
- parse error. Ignore the token.
- A comment token
- Insert a comment as the last child of the
Document
object. - A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- Ignore the token.
- A start tag whose tag name is "html"
-
Create an element for the token in the HTML namespace, with the
Document
as the intended parent. Append it to theDocument
object. Put this element in the stack of open elements.If the
Document
is being loaded as part of navigation of a browsing context, run these steps:- If the result of running match service worker
registration for the
Document
’s address is non-null, run the application cache selection algorithm passing theDocument
object with no manifest. -
Otherwise, run these substeps:
- If the newly created element has a
manifest
attribute whose value is not the empty string, then parse the value of that attribute, relative to the newly created element, and if that is successful, run the application cache selection algorithm passing theDocument
object with the result of applying the URL serializer algorithm to the resulting URL string with the exclude fragment flag set. - Otherwise, run the application cache selection algorithm passing the
Document
object with no manifest.
- If the newly created element has a
Switch the insertion mode to "before head".
- If the result of running match service worker
registration for the
- An end tag whose tag name is one of: "head", "body", "html", "br"
- Act as described in the "anything else" entry below.
- Any other end tag
- parse error. Ignore the token.
- Anything else
-
Create an
html
element whose node document is theDocument
object. Append it to theDocument
object. Put this element in the stack of open elements.If the
Document
is being loaded as part of navigation of a browsing context, then: run the application cache selection algorithm with no manifest, passing it theDocument
object.Switch the insertion mode to "before head", then reprocess the token.
The root element can end up being removed from the Document
object, e.g., by
scripts; nothing in particular happens in such cases, content continues being appended to the
nodes as described in the next section.
8.2.5.4.3. The "before head" insertion mode
When the user agent is to apply the rules for the "before head" insertion mode, the user agent must handle the token as follows:
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- Ignore the token.
- A comment token
- Insert a comment.
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "html"
- Process the token using the rules for the "in body" insertion mode.
- A start tag whose tag name is "head"
-
Insert an HTML element for the token.
Set the
head
element pointer to the newly createdhead
element.Switch the insertion mode to "in head".
- An end tag whose tag name is one of: "head", "body", "html", "br"
-
Act as described in the "anything else" entry below.
- Any other end tag
-
parse error. Ignore the token.
- Anything else
-
Insert an HTML element for a "head" start tag token with no attributes.
Set the
head
element pointer to the newly createdhead
element.Switch the insertion mode to "in head".
Reprocess the current token.
8.2.5.4.4. The "in head" insertion mode
When the user agent is to apply the rules for the "in head" insertion mode, the user agent must handle the token as follows:
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- Insert the character.
- A comment token
- Insert a comment.
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "html"
- Process the token using the rules for the "in body" insertion mode.
- A start tag whose tag name is one of: "base", "basefont", "bgsound", "link"
-
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token’s self-closing flag, if it is set.
- A start tag whose tag name is "meta"
-
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token’s self-closing flag, if it is set.
If the element has a
charset
attribute, and getting an encoding from its value results in an encoding, and the confidence is currently tentative, then change the encoding to the resulting encoding.Otherwise, if the element has an
http-equiv
attribute whose value is an ASCII case-insensitive match for the string "Content-Type
", and the element has acontent
attribute, and applying the algorithm for extracting a character encoding from ameta
element to that attribute’s value returns an encoding, and the confidence is currently tentative, then change the encoding to the extracted encoding. - A start tag whose tag name is "title"
- Follow the generic RCDATA element parsing algorithm.
- A start tag whose tag name is "noscript", if the scripting flag is enabled
- A start tag whose tag name is one of: "noframes", "style"
- Follow the generic raw text element parsing algorithm.
- A start tag whose tag name is "noscript", if the scripting flag is disabled
-
Insert an HTML element for the token.
Switch the insertion mode to "in head noscript".
- A start tag whose tag name is "script"
-
Run these steps:
- Let the adjusted insertion location be the appropriate place for inserting a node.
- Create an element for the token in the HTML namespace, with the intended parent being the element in which the adjusted insertion location finds itself.
-
Mark the element as being "parser-inserted" and unset the element’s "non-blocking" flag.
This ensures that, if the script is external, any
document.write()
calls in the script will execute in-line, instead of blowing the document away, as would happen in most other cases. It also prevents the script from executing until the end tag is seen. - If the parser was originally created for the HTML fragment parsing
algorithm, then mark the
script
element as "already started". (fragment case) - Insert the newly created element at the adjusted insertion location.
- Push the element onto the stack of open elements so that it is the new current node.
- Switch the tokenizer to the §8.2.4.6 Script data state.
- Let the original insertion mode be the current insertion mode.
- Switch the insertion mode to "text".
- An end tag whose tag name is "head"
-
Pop the current node (which will be the
head
element) off the stack of open elements.Switch the insertion mode to "after head".
- An end tag whose tag name is one of: "body", "html", "br"
- Act as described in the "anything else" entry below.
- A start tag whose tag name is "template"
-
Insert an HTML element for the token.
Insert a marker at the end of the list of active formatting elements.
Set the frameset-ok flag to "not ok".
Switch the insertion mode to "in template".
Push "in template" onto the stack of template insertion modes so that it is the new current template insertion mode.
- An end tag whose tag name is "template"
-
If there is no
template
element on the stack of open elements, then this is a parse error; ignore the token.Otherwise, run these steps:
- Generate all implied end tags thoroughly.
- If the current node is not a
template
element, then this is a parse error. - Pop elements from the stack of open elements until a
template
element has been popped from the stack. - Clear the list of active formatting elements up to the last marker.
- Pop the current template insertion mode off the stack of template insertion modes.
- Reset the insertion mode appropriately.
- A start tag whose tag name is "head"
- Any other end tag
- parse error. Ignore the token.
- Anything else
-
Pop the current node (which will be the
head
element) off the stack of open elements.Switch the insertion mode to "after head".
Reprocess the token.
8.2.5.4.5. The "in head noscript" insertion mode
When the user agent is to apply the rules for the "in head noscript" insertion mode, the user agent must handle the token as follows:
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "html"
-
Process the token using the rules for the "in body" insertion mode.
- An end tag whose tag name is "noscript"
-
Pop the current node (which will be a
noscript
element) from the stack of open elements; the new current node will be ahead
element.Switch the insertion mode to "in head".
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C
FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- A comment token
- A start tag whose tag name is one of: "basefont", "bgsound", "link", "meta", "noframes", "style"
- A comment token
-
Process the token using the rules for the "in head" insertion mode.
- An end tag whose tag name is "br"
- Act as described in the "anything else" entry below.
- A start tag whose tag name is one of: "head", "noscript"
- Any other end tag
- parse error. Ignore the token.
- Anything else
-
Pop the current node (which will be a
noscript
element) from the stack of open elements; the new current node will be ahead
element.Switch the insertion mode to "in head".
Reprocess the token.
8.2.5.4.6. The "after head" insertion mode
When the user agent is to apply the rules for the "after head" insertion mode, the user agent must handle the token as follows:
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- Insert the character.
- A comment token
- Insert a comment.
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "html"
-
Process the token using the rules for the "in body" insertion mode.
- A start tag whose tag name is "body"
-
Insert an HTML element for the token.
Set the frameset-ok flag to "not ok".
Switch the insertion mode to "in body".
- A start tag whose tag name is "frameset"
-
Insert an HTML element for the token.
Switch the insertion mode to "in frameset".
- A start tag whose tag name is one of: "base", "basefont", "bgsound", "link", "meta", "noframes", "script", "style", "template", "title"
-
Push the node pointed to by the
head
element pointer onto the stack of open elements.Process the token using the rules for the "in head" insertion mode.
Remove the node pointed to by the
head
element pointer from the stack of open elements. (It might not be the current node at this point.)The
head
element pointer cannot be null at this point. - An end tag whose tag name is "template"
- Process the token using the rules for the "in head" insertion mode.
- An end tag whose tag name is one of: "body", "html", "br"
- Act as described in the "anything else" entry below.
- A start tag whose tag name is "head"
- Any other end tag
- parse error. Ignore the token.
- Anything else
-
Insert an HTML element for a "body" start tag token with no attributes.
Switch the insertion mode to "in body".
Reprocess the current token.
8.2.5.4.7. The "in body" insertion mode
When the user agent is to apply the rules for the "in body" insertion mode, the user agent must handle the token as follows:
- A character token that is U+0000 NULL
-
parse error. Ignore the token.
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- Any other character token
-
reconstruct the active formatting elements, if any.
Set the frameset-ok flag to "not ok".
- A comment token
- Insert a comment.
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "html"
-
If there is a
template
element on the stack of open elements, then ignore the token.Otherwise, for each attribute on the token, check to see if the attribute is already present on the top element of the stack of open elements. If it is not, add the attribute and its corresponding value to that element.
- A start tag whose tag name is one of: "base", "basefont", "bgsound", "link", "meta",
"noframes", "script", "style", "template", "title"
- An end tag whose tag name is "template"
- Process the token using the rules for the "in head" insertion mode.
- A start tag whose tag name is "body"
-
If the second element on the stack of open elements is not a
body
element, if the stack of open elements has only one node on it, or if there is atemplate
element on the stack of open elements, then ignore the token. (fragment case)Otherwise, set the frameset-ok flag to "not ok"; then, for each attribute on the token, check to see if the attribute is already present on the
body
element (the second element) on the stack of open elements, and if it is not, add the attribute and its corresponding value to that element. - A start tag whose tag name is "frameset"
-
If the stack of open elements has only one node on it, or if the second element on the stack of open elements is not a
body
element, then ignore the token. (fragment case)If the frameset-ok flag is set to "not ok", ignore the token.
Otherwise, run the following steps:
- Remove the second element on the stack of open elements from its parent node, if it has one.
- Pop all the nodes from the bottom of the stack of open elements, from the current node up to, but not including, the root
html
element. - Insert an HTML element for the token.
- Switch the insertion mode to "in frameset".
- An end-of-file token
-
If the stack of template insertion modes is not empty, then process the token using the rules for the "in template" insertion mode.
Otherwise, follow these steps:
- If there is a node in the stack of open elements that is not either a
dd
element, adt
element, anli
element, anoptgroup
element, anoption
element, ap
element, anrb
element, anrp
element, anrt
element, anrtc
element, atbody
element, atd
element, atfoot
element, ath
element, athead
element, atr
element, thebody
element, or thehtml
element, then this is a parse error. - Stop parsing.
- If there is a node in the stack of open elements that is not either a
- An end tag whose tag name is "body"
-
If the stack of open elements does not have a
body
element in scope, this is a parse error; ignore the token.Otherwise, if there is a node in the stack of open elements that is not either a
dd
element, adt
element, anli
element, anoptgroup
element, anoption
element, ap
element, anrb
element, anrp
element, anrt
element, anrtc
element, atbody
element, atd
element, atfoot
element, ath
element, athead
element, atr
element, thebody
element, or thehtml
element, then this is a parse error.Switch the insertion mode to "after body".
- An end tag whose tag name is "html"
-
If the stack of open elements does not have a
body
element in scope, this is a parse error; ignore the token.Otherwise, if there is a node in the stack of open elements that is not either a
dd
element, adt
element, anli
element, anoptgroup
element, anoption
element, ap
element, anrb
element, anrp
element, anrt
element, anrtc
element, atbody
element, atd
element, atfoot
element, ath
element, athead
element, atr
element, thebody
element, or thehtml
element, then this is a parse error.Switch the insertion mode to "after body".
Reprocess the token.
- A start tag whose tag name is one of: "address", "article", "aside", "blockquote", "center", "details", "dir", "div", "dl", "fieldset", "figcaption", "figure", "footer", "header", "main", "menu", "nav", "ol", "p", "section", "summary", "ul"
-
If the stack of open elements has a
p
element in button scope, then close ap
element.Insert an HTML element for the token.
- A start tag whose tag name is one of: "h1", "h2", "h3", "h4", "h5", "h6"
-
If the stack of open elements has a
p
element in button scope, then close ap
element.If the current node is an HTML element whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6", then this is a parse error; pop the current node off the stack of open elements.
Insert an HTML element for the token.
- A start tag whose tag name is one of: "pre", "listing"
-
If the stack of open elements has a
p
element in button scope, then close ap
element.Insert an HTML element for the token.
If the next token is a U+000A LINE FEED (LF) character token, then ignore that token and move on to the next one. (Newlines at the start of
pre
blocks are ignored as an authoring convenience.)Set the frameset-ok flag to "not ok".
- A start tag whose tag name is "form"
-
If the
form
element pointer is not null, and there is notemplate
element on the stack of open elements, then this is a parse error; ignore the token.Otherwise:
If the stack of open elements has a
p
element in button scope, then close ap
element.Insert an HTML element for the token, and, if there is no
template
element on the stack of open elements, set theform
element pointer to point to the element created. - A start tag whose tag name is "li"
-
Run these steps:
- Set the frameset-ok flag to "not ok".
- Initialize node to be the current node (the bottommost node of the stack).
-
Loop: If node is an
li
element, then run these substeps:- Generate implied end tags, except for
li
elements. - If the current node is not an
li
element, then this is a parse error. - Pop elements from the stack of open elements until an
li
element has been popped from the stack. - Jump to the step labeled done below.
- Generate implied end tags, except for
- If node is in the special category, but is not an
address
,div
, orp
element, then jump to the step labeled done below. - Otherwise, set node to the previous entry in the stack of open elements and return to the step labeled loop.
- Done: If the stack of open elements has a
p
element in button scope, then close ap
element. - Finally, insert an HTML element for the token.
- A start tag whose tag name is one of: "dd", "dt"
-
Run these steps:
- Set the frameset-ok flag to "not ok".
- Initialize node to be the current node (the bottommost node of the stack).
-
Loop: If node is a
dd
element, then run these substeps:- Generate implied end tags, except for
dd
elements. - If the current node is not a
dd
element, then this is a parse error. - Pop elements from the stack of open elements until a
dd
element has been popped from the stack. - Jump to the step labeled done below.
- Generate implied end tags, except for
-
If node is a
dt
element, then run these substeps:- Generate implied end tags, except for
dt
elements. - If the current node is not a
dt
element, then this is a parse error. - Pop elements from the stack of open elements until a
dt
element has been popped from the stack. - Jump to the step labeled done below.
- Generate implied end tags, except for
- If node is in the special category, but is not an
address
,div
, orp
element, then jump to the step labeled done below. - Otherwise, set node to the previous entry in the stack of open elements and return to the step labeled loop.
- Done: If the stack of open elements has a
p
element in button scope, then close ap
element. - Finally, insert an HTML element for the token.
- A start tag whose tag name is "plaintext"
-
If the stack of open elements has a
p
element in button scope, then close ap
element.Insert an HTML element for the token.
Switch the tokenizer to the §8.2.4.7 PLAINTEXT state.
Once a start tag with the tag name "plaintext" has been seen, that will be the last token ever seen other than character tokens (and the end-of-file token), because there is no way to switch out of the §8.2.4.7 PLAINTEXT state.
- A start tag whose tag name is "button"
-
-
If the stack of open elements has a
button
element in scope, then run these substeps:- parse error.
- Generate implied end tags.
- Pop elements from the stack of open elements until a
button
element has been popped from the stack.
- reconstruct the active formatting elements, if any.
- Insert an HTML element for the token.
- Set the frameset-ok flag to "not ok".
-
- An end tag whose tag name is one of: "address", "article", "aside", "blockquote", "button", "center", "details", "dir", "div", "dl", "fieldset", "figcaption", "figure", "footer", "header", "listing", "main", "menu", "nav", "ol", "pre", "section", "summary", "ul"
-
If the stack of open elements does not have an element in scope that is an HTML element with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, run these steps:
- Generate implied end tags.
- If the current node is not an HTML element with the same tag name as that of the token, then this is a parse error.
- Pop elements from the stack of open elements until an HTML element with the same tag name as the token has been popped from the stack.
- An end tag whose tag name is "form"
-
If there is no
template
element on the stack of open elements, then run these substeps:- Let node be the element that the
form
element pointer is set to, or null if it is not set to an element. - Set the
form
element pointer to null. - If node is null or if the stack of open elements does not have node in scope, then this is a parse error; abort these steps and ignore the token.
- Generate implied end tags.
- If the current node is not node, then this is a parse error.
- Remove node from the stack of open elements.
If there is a
template
element on the stack of open elements, then run these substeps instead:- If the stack of open elements does not have a
form
element in scope, then this is a parse error; abort these steps and ignore the token. - Generate implied end tags.
- If the current node is not a
form
element, then this is a parse error. - Pop elements from the stack of open elements until a
form
element has been popped from the stack.
- Let node be the element that the
- An end tag whose tag name is "p"
-
If the stack of open elements does not have a
p
element in button scope, then this is a parse error; insert an HTML element for a "p" start tag token with no attributes. - An end tag whose tag name is "li"
-
If the stack of open elements does not have an
li
element in list item scope, then this is a parse error; ignore the token.Otherwise, run these steps:
- Generate implied end tags, except for
li
elements. - If the current node is not an
li
element, then this is a parse error. - Pop elements from the stack of open elements until an
li
element has been popped from the stack.
- Generate implied end tags, except for
- An end tag whose tag name is one of: "dd", "dt"
-
If the stack of open elements does not have an element in scope that is an HTML element with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, run these steps:
- Generate implied end tags, except for html elements with the same tag name as the token.
- If the current node is not an HTML element with the same tag name as that of the token, then this is a parse error.
- Pop elements from the stack of open elements until an HTML element with the same tag name as the token has been popped from the stack.
- An end tag whose tag name is one of: "h1", "h2", "h3", "h4", "h5", "h6"
-
If the stack of open elements does not have an element in scope that is an HTML element and whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6", then this is a parse error; ignore the token.
Otherwise, run these steps:
- Generate implied end tags.
- If the current node is not an HTML element with the same tag name as that of the token, then this is a parse error.
- Pop elements from the stack of open elements until an HTML element whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6" has been popped from the stack.
- An end tag whose tag name is "sarcasm"
- Take a deep breath, then act as described in the "any other end tag" entry below.
- A start tag whose tag name is "a"
-
If the list of active formatting elements contains an
a
element between the end of the list and the last marker on the list (or the start of the list if there is no marker on the list), then this is a parse error; run the adoption agency algorithm for the tag name "a", then remove that element from the list of active formatting elements and the stack of open elements if the adoption agency algorithm didn’t already remove it (it might not have if the element is not in table scope).In the non-conforming stream
<a href="a">a<table><a href="b">b</table>x
, the firsta
element would be closed upon seeing the second one, and the "x" character would be inside a link to "b", not to "a". This is despite the fact that the outera
element is not in table scope (meaning that a regular</a>
end tag at the start of the table wouldn’t close the outera
element). The result is that the twoa
elements are indirectly nested inside each other — non-conforming markup will often result in non-conforming DOMs when parsed.reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Push onto the list of active formatting elements that element.
- A start tag whose tag name is one of: "b", "big", "code", "em", "font", "i", "s", "small", "strike", "strong", "tt", "u"
-
reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Push onto the list of active formatting elements that element.
- A start tag whose tag name is "nobr"
-
reconstruct the active formatting elements, if any.
If the stack of open elements has a
nobr
element in scope, then this is a parse error; run the adoption agency algorithm for the tag name "nobr", then once again reconstruct the active formatting elements, if any.Insert an HTML element for the token. Push onto the list of active formatting elements that element.
- An end tag whose tag name is one of: "a", "b", "big", "code", "em", "font", "i", "nobr", "s", "small", "strike", "strong", "tt", "u"
-
Run the adoption agency algorithm for the token’s tag name.
- A start tag whose tag name is one of: "applet", "marquee", "object"
-
reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Insert a marker at the end of the list of active formatting elements.
Set the frameset-ok flag to "not ok".
- An end tag token whose tag name is one of: "applet", "marquee", "object"
-
If the stack of open elements does not have an element in scope that is an HTML element with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, run these steps:
- Generate implied end tags.
- If the current node is not an HTML element with the same tag name as that of the token, then this is a parse error.
- Pop elements from the stack of open elements until an HTML element with the same tag name as the token has been popped from the stack.
- Clear the list of active formatting elements up to the last marker.
- A start tag whose tag name is "table"
-
If the
Document
is not set to quirks mode, and the stack of open elements has ap
element in button scope, then close ap
element.Insert an HTML element for the token.
Set the frameset-ok flag to "not ok".
Switch the insertion mode to "in table".
- An end tag whose tag name is "br"
-
parse error. Drop the attributes from the token, and act as described in the next entry; i.e., act as if this was a "br" start tag token with no attributes, rather than the end tag token that it actually is.
- A start tag whose tag name is one of: "area", "br", "embed", "img", "keygen", "wbr"
-
reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token’s self-closing flag, if it is set.
Set the frameset-ok flag to "not ok".
- A start tag whose tag name is "input"
-
reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token’s self-closing flag, if it is set.
If the token does not have an attribute with the name "type", or if it does, but that attribute’s value is not an ASCII case-insensitive match for the string "
hidden
", then: set the frameset-ok flag to "not ok". - A start tag whose tag name is one of: "menuitem", "param", "source", "track"
-
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token’s self-closing flag, if it is set.
- A start tag whose tag name is "hr"
-
If the stack of open elements has a
p
element in button scope, then close ap
element.Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token’s self-closing flag, if it is set.
Set the frameset-ok flag to "not ok".
- A start tag whose tag name is "image"
-
parse error. Change the token’s tag name to "img" and reprocess it. (Don’t ask.)
- A start tag whose tag name is "textarea"
-
Run these steps:
- Insert an HTML element for the token.
- If the next token is a U+000A LINE FEED (LF) character token, then ignore
that token and move on to the next one. (Newlines at the start of
textarea
elements are ignored as an authoring convenience.) - Switch the tokenizer to the §8.2.4.3 RCDATA state.
- Let the original insertion mode be the current insertion mode.
- Set the frameset-ok flag to "not ok".
- Switch the insertion mode to "text".
- A start tag whose tag name is "xmp"
-
If the stack of open elements has a
p
element in button scope, then close ap
element.reconstruct the active formatting elements, if any.
Set the frameset-ok flag to "not ok".
Follow the generic raw text element parsing algorithm.
- A start tag whose tag name is "iframe"
-
Set the frameset-ok flag to "not ok".
Follow the generic raw text element parsing algorithm.
- A start tag whose tag name is "noembed"
- A start tag whose tag name is "noscript", if the scripting flag is enabled
-
Follow the generic raw text element parsing algorithm.
- A start tag whose tag name is "select"
-
reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Set the frameset-ok flag to "not ok".
If the insertion mode is one of "in table", "in caption", "in table body", "in row", or "in cell", then switch the insertion mode to "in select in table". Otherwise, switch the insertion mode to "in select".
- A start tag whose tag name is one of: "optgroup", "option"
-
If the current node is an
option
element, then pop the current node off the stack of open elements.reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
- A start tag whose tag name is one of: "rb", "rtc"
-
If the stack of open elements has a
ruby
element in scope, then generate implied end tags. If the current node is not now aruby
element, this is a parse error.Insert an HTML element for the token.
- A start tag whose tag name is one of: "rp", "rt"
-
If the stack of open elements has a
ruby
element in scope, then generate implied end tags, except forrtc
elements. If the current node is not then aruby
element or anrtc
element, this is a parse error.Insert an HTML element for the token.
- A start tag whose tag name is "math"
-
reconstruct the active formatting elements, if any.
Adjust MathML attributes for the token. (This fixes the case of MathML attributes that are not all lowercase.)
Adjust foreign attributes for the token. (This fixes the use of namespaced attributes, in particular XLink.)
Insert a foreign element for the token, in the MathML namespace.
If the token has its self-closing flag set, pop the current node off the stack of open elements and acknowledge the token’s self-closing flag.
- A start tag whose tag name is "svg"
-
reconstruct the active formatting elements, if any.
Adjust SVG attributes for the token. (This fixes the case of SVG attributes that are not all lowercase.)
Adjust foreign attributes for the token. (This fixes the use of namespaced attributes, in particular XLink in SVG.)
Insert a foreign element for the token, in the SVG namespace.
If the token has its self-closing flag set, pop the current node off the stack of open elements and acknowledge the token’s self-closing flag.
- A start tag whose tag name is one of: "caption", "col", "colgroup", "frame", "head", "tbody", "td", "tfoot", "th", "thead", "tr"
-
parse error. Ignore the token.
- Any other start tag
-
reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
This element will be an ordinary element.
- Any other end tag
-
Run these steps:
- Initialize node to be the current node (the bottommost node of the stack).
-
Loop: If node is an HTML element with the same tag name as the token, then:
- Generate implied end tags, except for html elements with the same tag name as the token.
- If node is not the current node, then this is a parse error.
- Pop all the nodes from the current node up to node, including node, then stop these steps.
- Otherwise, if node is in the special category, then this is a parse error; ignore the token, and abort these steps.
- Set node to the previous entry in the stack of open elements.
- Return to the step labeled loop.
When the steps above say the user agent is to close a p
element, it
means that the user agent must run the following steps:
- Generate implied end tags, except for
p
elements. - If the current node is not a
p
element, then this is a parse error. - Pop elements from the stack of open elements until a
p
element has been popped from the stack.
The adoption agency algorithm, which takes as its only argument a tag name subject for which the algorithm is being run, consists of the following steps:
- If the current node is an HTML element whose tag name is subject, and the current node is not in the list of active formatting elements, then pop the current node off the stack of open elements, and abort these steps.
- Let outer loop counter be zero.
- Outer loop: If outer loop counter is greater than or equal to eight, then abort these steps.
- Increment outer loop counter by one.
-
Let formatting element be the last element in the list of active formatting elements that:
- is between the end of the list and the last marker in the list, if any, or the start of the list otherwise, and
- has the tag name subject.
If there is no such element, then abort these steps and instead act as described in the "any other end tag" entry above.
- If formatting element is not in the stack of open elements, then this is a parse error; remove the element from the list, and abort these steps.
- If formatting element is in the stack of open elements, but the element is not in scope, then this is a parse error; abort these steps.
- If formatting element is not the current node, this is a parse error. (But do not abort these steps.)
- Let furthest block be the topmost node in the stack of open elements that is lower in the stack than formatting element, and is an element in the special category. There might not be one.
- If there is no furthest block, then the user agent must first pop all the nodes from the bottom of the stack of open elements, from the current node up to and including formatting element, then remove formatting element from the list of active formatting elements, and finally abort these steps.
- Let common ancestor be the element immediately above formatting element in the stack of open elements.
- Let a bookmark note the position of formatting element in the list of active formatting elements relative to the elements on either side of it in the list.
-
Let node and last node be furthest block. Follow these steps:
- Let inner loop counter be zero.
- Inner loop: Increment inner loop counter by one.
- Let node be the element immediately above node in the stack of open elements, or if node is no longer in the stack of open elements (e.g., because it got removed by this algorithm), the element that was immediately above node in the stack of open elements before node was removed.
- If node is formatting element, then go to the next step in the overall algorithm.
- If inner loop counter is greater than three and node is in the list of active formatting elements, then remove node from the list of active formatting elements.
- If node is not in the list of active formatting elements, then remove node from the stack of open elements and then go back to the step labeled inner loop.
- Create an element for the token for which the element node was created, in the HTML namespace, with common ancestor as the intended parent; replace the entry for node in the list of active formatting elements with an entry for the new element, replace the entry for node in the stack of open elements with an entry for the new element, and let node be the new element.
- If last node is furthest block, then move the aforementioned bookmark to be immediately after the new node in the list of active formatting elements.
- Insert last node into node, first removing it from its previous parent node if any.
- Let last node be node.
- Return to the step labeled inner loop.
- Insert whatever last node ended up being in the previous step at the appropriate place for inserting a node, but using common ancestor as the override target.
- Create an element for the token for which formatting element was created, in the HTML namespace, with furthest block as the intended parent.
- Take all of the child nodes of furthest block and append them to the element created in the last step.
- Append that new element to furthest block.
- Remove formatting element from the list of active formatting elements, and insert the new element into the list of active formatting elements at the position of the aforementioned bookmark.
- Remove formatting element from the stack of open elements, and insert the new element into the stack of open elements immediately below the position of furthest block in that stack.
- Jump back to the step labeled outer loop.
This algorithm’s name, the "adoption agency algorithm", comes from the way it causes elements to change parents, and is in contrast with other possible algorithms for dealing with misnested content, which included the "incest algorithm", the "secret affair algorithm", and the "Heizenberg algorithm".
8.2.5.4.8. The "text" insertion mode
When the user agent is to apply the rules for the "text" insertion mode, the user agent must handle the token as follows:
- A character token
-
This can never be a U+0000 NULL character; the tokenizer converts those to U+FFFD REPLACEMENT CHARACTER characters.
- An end-of-file token
-
If the current node is a
script
element, mark thescript
element as "already started".Pop the current node off the stack of open elements.
Switch the insertion mode to the original insertion mode and reprocess the token.
- An end tag whose tag name is "script"
-
If the JavaScript execution context stack is empty, perform a microtask checkpoint.
Let script be the current node (which will be a
script
element).Pop the current node off the stack of open elements.
Switch the insertion mode to the original insertion mode.
Let the old insertion point have the same value as the current insertion point. Let the insertion point be just before the next input character.
Increment the parser’s script nesting level by one.
Prepare the script. This might cause some script to execute, which might cause new characters to be inserted into the tokenizer, and might cause the tokenizer to output more tokens, resulting in a reentrant invocation of the parser.
Decrement the parser’s script nesting level by one. If the parser’s script nesting level is zero, then set the parser pause flag to false.
Let the insertion point have the value of the old insertion point. (In other words, restore the insertion point to its previous value. This value might be the "undefined" value.)
At this stage, if there is a pending parsing-blocking script, then:
- If the script nesting level is not zero:
-
Set the parser pause flag to true, and abort the processing of any nested invocations of the tokenizer, yielding control back to the caller. (Tokenization will resume when the caller returns to the "outer" tree construction stage.)
The tree construction stage of this particular parser is being called reentrantly, say from a call to
document.write()
. - Otherwise:
-
Run these steps:
- Let the script be the pending parsing-blocking script. There is no longer a pending parsing-blocking script.
- Block the tokenizer for this instance of the HTML parser, such that the event loop will not run tasks that invoke the tokenizer.
- If the parser’s
Document
has a style sheet that is blocking scripts or the script’s "ready to be parser-executed" flag is not set: spin the event loop until the parser’sDocument
has no style sheet that is blocking scripts and the script’s "ready to be parser-executed" flag is set. -
If this parser has been aborted in the meantime, abort these steps.
This could happen if, e.g., while the spin the event loop algorithm is running, the browsing context gets closed, or the
document.open()
method gets invoked on theDocument
. - Unblock the tokenizer for this instance of the HTML parser, such that tasks that invoke the tokenizer can again be run.
- Let the insertion point be just before the next input character.
- Increment the parser’s script nesting level by one (it should be zero before this step, so this sets it to one).
- Execute the script.
- Decrement the parser’s script nesting level by one. If the parser’s script nesting level is zero (which it always should be at this point), then set the parser pause flag to false.
- Let the insertion point be undefined again.
- If there is once again a pending parsing-blocking script, then repeat these steps from step 1.
- Any other end tag
-
Pop the current node off the stack of open elements.
Switch the insertion mode to the original insertion mode.
8.2.5.4.9. The "in table" insertion mode
When the user agent is to apply the rules for the "in table" insertion mode, the user agent must handle the token as follows:
- A character token, if the current node is
table
,tbody
,tfoot
,thead
, ortr
element -
Let the pending table character tokens be an empty list of tokens.
Let the original insertion mode be the current insertion mode.
Switch the insertion mode to "in table text" and reprocess the token.
- A comment token
- Insert a comment.
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "caption"
-
Clear the stack back to a table context. (See below.)
Insert a marker at the end of the list of active formatting elements.
Insert an HTML element for the token, then switch the insertion mode to "in caption".
- A start tag whose tag name is "colgroup"
-
Clear the stack back to a table context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in column group".
- A start tag whose tag name is "col"
-
Clear the stack back to a table context. (See below.)
Insert an HTML element for a "colgroup" start tag token with no attributes, then switch the insertion mode to "in column group".
Reprocess the current token.
- A start tag whose tag name is one of: "tbody", "tfoot", "thead"
-
Clear the stack back to a table context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in table body".
- A start tag whose tag name is one of: "td", "th", "tr"
-
Clear the stack back to a table context. (See below.)
Insert an HTML element for a "tbody" start tag token with no attributes, then switch the insertion mode to "in table body".
Reprocess the current token.
- A start tag whose tag name is "table"
-
If the stack of open elements does not have a
table
element in table scope, ignore the token.Otherwise:
Pop elements from this stack until a
table
element has been popped from the stack.Reset the insertion mode appropriately.
Reprocess the token.
- An end tag whose tag name is "table"
-
If the stack of open elements does not have a
table
element in table scope, this is a parse error; ignore the token.Otherwise:
Pop elements from this stack until a
table
element has been popped from the stack. - An end tag whose tag name is one of: "body", "caption", "col", "colgroup", "html", "tbody", "td", "tfoot", "th", "thead", "tr"
- parse error. Ignore the token.
- A start tag whose tag name is one of: "style", "script", "template"
- An end tag whose tag name is "template"
-
Process the token using the rules for the "in head" insertion mode.
- A start tag whose tag name is "input"
-
If the token does not have an attribute with the name "type", or if it does, but that attribute’s value is not an ASCII case-insensitive match for the string "
hidden
", then: act as described in the "anything else" entry below.Otherwise:
Insert an HTML element for the token.
Pop that
input
element off the stack of open elements.Acknowledge the token’s self-closing flag, if it is set.
- A start tag whose tag name is "form"
-
If there is a
template
element on the stack of open elements, or if theform
element pointer is not null, ignore the token.Otherwise:
Insert an HTML element for the token, and set the
form
element pointer to point to the element created.Pop that
form
element off the stack of open elements. - An end-of-file token
-
Process the token using the rules for the "in body" insertion mode.
- Anything else
-
parse error. Enable foster parenting, process the token using the rules for the "in body" insertion mode, and then disable foster parenting.
When the steps above require the user agent to clear the stack back to a table context, it
means that the user agent must, while the current node is not a table
, template
, or html
element, pop elements from the stack of open
elements.
This is the same list of elements as used in the has an element in table scope steps.
The current node being an html
element after this
process is a fragment case.
8.2.5.4.10. The "in table text" insertion mode
When the user agent is to apply the rules for the "in table text" insertion mode, the user agent must handle the token as follows:
- A character token that is U+0000 NULL
-
parse error. Ignore the token.
- Any other character token
-
Append the character token to the pending table character tokens list.
- Anything else
-
If any of the tokens in the pending table character tokens list are character tokens that are not space characters, then this is a parse error: reprocess the character tokens in the pending table character tokens list using the rules given in the "anything else" entry in the "in table" insertion mode.
Otherwise, insert the characters given by the pending table character tokens list.
Switch the insertion mode to the original insertion mode and reprocess the token.
8.2.5.4.11. The "in caption" insertion mode
When the user agent is to apply the rules for the "in caption" insertion mode, the user agent must handle the token as follows:
- An end tag whose tag name is "caption"
-
If the stack of open elements does not have a
caption
element in table scope, this is a parse error; ignore the token. (fragment case)Otherwise:
Now, if the current node is not a
caption
element, then this is a parse error.Pop elements from this stack until a
caption
element has been popped from the stack.Clear the list of active formatting elements up to the last marker.
Switch the insertion mode to "in table".
- A start tag whose tag name is one of: "caption", "col", "colgroup", "tbody", "td", "tfoot",
"th", "thead", "tr"
- An end tag whose tag name is "table"
-
If the stack of open elements does not have a
caption
element in table scope, this is a parse error; ignore the token. (fragment case)Otherwise:
Now, if the current node is not a
caption
element, then this is a parse error.Pop elements from this stack until a
caption
element has been popped from the stack.Clear the list of active formatting elements up to the last marker.
Switch the insertion mode to "in table".
Reprocess the token.
- An end tag whose tag name is one of: "body", "col", "colgroup", "html", "tbody", "td", "tfoot", "th", "thead", "tr"
- parse error. Ignore the token.
- Anything else
-
Process the token using the rules for the "in body" insertion mode.
8.2.5.4.12. The "in column group" insertion mode
When the user agent is to apply the rules for the "in column group" insertion mode, the user agent must handle the token as follows:
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- Insert the character.
- A comment token
- Insert a comment.
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "html"
-
Process the token using the rules for the "in body" insertion mode.
- A start tag whose tag name is "col"
-
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token’s self-closing flag, if it is set.
- An end tag whose tag name is "colgroup"
-
If the current node is not a
colgroup
element, then this is a parse error; ignore the token.Otherwise, pop the current node from the stack of open elements. Switch the insertion mode to "in table".
- An end tag whose tag name is "col"
- parse error. Ignore the token.
- A start tag whose tag name is "template"
- An end tag whose tag name is "template"
-
Process the token using the rules for the "in head" insertion mode.
- An end-of-file token
-
Process the token using the rules for the "in body" insertion mode.
- Anything else
-
If the current node is not a
colgroup
element, then this is a parse error; ignore the token.Otherwise, pop the current node from the stack of open elements.
Switch the insertion mode to "in table".
Reprocess the token.
8.2.5.4.13. The "in table body" insertion mode
When the user agent is to apply the rules for the "in table body" insertion mode, the user agent must handle the token as follows:
- A start tag whose tag name is "tr"
-
Clear the stack back to a table body context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in row".
- A start tag whose tag name is one of: "th", "td"
-
Clear the stack back to a table body context. (See below.)
Insert an HTML element for a "tr" start tag token with no attributes, then switch the insertion mode to "in row".
Reprocess the current token.
- An end tag whose tag name is one of: "tbody", "tfoot", "thead"
-
If the stack of open elements does not have an element in table scope that is an HTML element with the same tag name as the token, this is a parse error; ignore the token.
Otherwise:
Clear the stack back to a table body context. (See below.)
Pop the current node from the stack of open elements. Switch the insertion mode to "in table".
- A start tag whose tag name is one of: "caption", "col",
"colgroup", "tbody", "tfoot", "thead"
- An end tag whose tag name is "table"
-
If the stack of open elements does not have a
tbody
,thead
, ortfoot
element in table scope, this is a parse error; ignore the token.Otherwise:
Clear the stack back to a table body context. (See below.)
Pop the current node from the stack of open elements. Switch the insertion mode to "in table".
Reprocess the token.
- An end tag whose tag name is one of: "body", "caption", "col", "colgroup", "html", "td", "th", "tr"
- parse error. Ignore the token.
- Anything else
- Process the token using the rules for the "in table" insertion mode.
When the steps above require the user agent to clear the stack back to a table body context,
it means that the user agent must, while the current node is not a tbody
, tfoot
, thead
, template
, or html
element, pop
elements from the stack of open elements.
The current node being an html
element after this
process is a fragment case.
8.2.5.4.14. The "in row" insertion mode
When the user agent is to apply the rules for the "in row" insertion mode, the user agent must handle the token as follows:
- A start tag whose tag name is one of: "th", "td"
-
Clear the stack back to a table row context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in cell".
Insert a marker at the end of the list of active formatting elements.
- An end tag whose tag name is "tr"
-
If the stack of open elements does not have a
tr
element in table scope, this is a parse error; ignore the token.Otherwise:
Clear the stack back to a table row context. (See below.)
Pop the current node (which will be a
tr
element) from the stack of open elements. Switch the insertion mode to "in table body". - A start tag whose tag name is one of: "caption", "col", "colgroup", "tbody", "tfoot",
"thead", "tr"
- An end tag whose tag name is "table"
-
If the stack of open elements does not have a
tr
element in table scope, this is a parse error; ignore the token.Otherwise:
Clear the stack back to a table row context. (See below.)
Pop the current node (which will be a
tr
element) from the stack of open elements. Switch the insertion mode to "in table body".Reprocess the token.
- An end tag whose tag name is one of: "tbody", "tfoot", "thead"
-
If the stack of open elements does not have an element in table scope that is an HTML element with the same tag name as the token, this is a parse error; ignore the token.
If the stack of open elements does not have a
tr
element in table scope, ignore the token.Otherwise:
Clear the stack back to a table row context. (See below.)
Pop the current node (which will be a
tr
element) from the stack of open elements. Switch the insertion mode to "in table body".Reprocess the token.
- An end tag whose tag name is one of: "body", "caption", "col", "colgroup", "html", "td", "th"
- parse error. Ignore the token.
- Anything else
-
Process the token using the rules for the "in table" insertion mode.
When the steps above require the user agent to clear the stack back to a table row context,
it means that the user agent must, while the current node is not a tr
, template
, or html
element, pop elements from the stack of open
elements.
The current node being an html
element after this
process is a fragment case.
8.2.5.4.15. The "in cell" insertion mode
When the user agent is to apply the rules for the "in cell" insertion mode, the user agent must handle the token as follows:
- An end tag whose tag name is one of: "td", "th"
-
If the stack of open elements does not have an element in table scope that is an HTML element with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise:
Now, if the current node is not an HTML element with the same tag name as the token, then this is a parse error.
Pop elements from the stack of open elements stack until an HTML element with the same tag name as the token has been popped from the stack.
Clear the list of active formatting elements up to the last marker.
Switch the insertion mode to "in row".
- A start tag whose tag name is one of: "caption", "col", "colgroup", "tbody", "td", "tfoot", "th", "thead", "tr"
-
If the stack of open elements does not have a
td
orth
element in table scope, then this is a parse error; ignore the token. (fragment case)Otherwise, close the cell (see below) and reprocess the token.
- An end tag whose tag name is one of: "body", "caption", "col", "colgroup", "html"
- parse error. Ignore the token.
- An end tag whose tag name is one of: "table", "tbody", "tfoot", "thead", "tr"
-
If the stack of open elements does not have an element in table scope that is an HTML element with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, close the cell (see below) and reprocess the token.
- Anything else
-
Process the token using the rules for the "in body" insertion mode.
Where the steps above say to close the cell, they mean to run the following algorithm:
- Generate implied end tags.
- If the current node is not now a
td
element or ath
element, then this is a parse error. - Pop elements from the stack of open elements stack until a
td
element or ath
element has been popped from the stack. - Clear the list of active formatting elements up to the last marker.
- Switch the insertion mode to "in row".
The stack of open elements cannot have both a td
and a th
element in table scope at the
same time, nor can it have neither when the close the cell algorithm is invoked.
8.2.5.4.16. The "in select" insertion mode
When the user agent is to apply the rules for the "in select" insertion mode, the user agent must handle the token as follows:
- A character token that is U+0000 NULL
- parse error. Ignore the token.
- Any other character token
- A comment token
- Insert a comment.
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "html"
-
Process the token using the rules for the "in body" insertion mode.
- A start tag whose tag name is "option"
-
If the current node is an
option
element, pop that node from the stack of open elements.Insert an HTML element for the token.
- A start tag whose tag name is "optgroup"
-
If the current node is an
option
element, pop that node from the stack of open elements.If the current node is an
optgroup
element, pop that node from the stack of open elements.Insert an HTML element for the token.
- An end tag whose tag name is "optgroup"
-
First, if the current node is an
option
element, and the node immediately before it in the stack of open elements is anoptgroup
element, then pop the current node from the stack of open elements.If the current node is an
optgroup
element, then pop that node from the stack of open elements. Otherwise, this is a parse error; ignore the token. - An end tag whose tag name is "option"
-
If the current node is an
option
element, then pop that node from the stack of open elements. Otherwise, this is a parse error; ignore the token. - An end tag whose tag name is "select"
-
If the stack of open elements does not have a
select
element in select scope, this is a parse error; ignore the token. (fragment case)Otherwise:
Pop elements from the stack of open elements until a
select
element has been popped from the stack. - A start tag whose tag name is "select"
-
If the stack of open elements does not have a
select
element in select scope, ignore the token. (fragment case)Otherwise:
Pop elements from the stack of open elements until a
select
element has been popped from the stack.Reset the insertion mode appropriately.
It just gets treated like an end tag.
- A start tag whose tag name is one of: "input", "keygen", "textarea"
-
If the stack of open elements does not have a
select
element in select scope, ignore the token. (fragment case)Otherwise:
Pop elements from the stack of open elements until a
select
element has been popped from the stack.Reset the insertion mode appropriately.
Reprocess the token.
- A start tag whose tag name is one of: "script", "template"
- An end tag whose tag name is "template"
-
Process the token using the rules for the "in head" insertion mode.
- An end-of-file token
-
Process the token using the rules for the "in body" insertion mode.
- Anything else
- parse error. Ignore the token.
8.2.5.4.17. The "in select in table" insertion mode
When the user agent is to apply the rules for the "in select in table" insertion mode, the user agent must handle the token as follows:
- A start tag whose tag name is one of: "caption", "table", "tbody", "tfoot", "thead", "tr", "td", "th"
-
Pop elements from the stack of open elements until a
select
element has been popped from the stack.Reset the insertion mode appropriately.
Reprocess the token.
- An end tag whose tag name is one of: "caption", "table", "tbody", "tfoot", "thead", "tr", "td", "th"
-
If the stack of open elements does not have an element in table scope that is an HTML element with the same tag name as that of the token, then ignore the token.
Otherwise:
Pop elements from the stack of open elements until a
select
element has been popped from the stack.Reset the insertion mode appropriately.
Reprocess the token.
- Anything else
-
Process the token using the rules for the "in select" insertion mode.
8.2.5.4.18. The "in template" insertion mode
When the user agent is to apply the rules for the "in template" insertion mode, the user agent must handle the token as follows:
- A character token
- A comment token
- A DOCTYPE token
- A comment token
-
Process the token using the rules for the "in body" insertion mode.
- A start tag whose tag name is one of: "base", "basefont", "bgsound", "link", "meta", "noframes", "script", "style", "template", "title"
- An end tag whose tag name is "template"
-
Process the token using the rules for the "in head" insertion mode.
- A start tag whose tag name is one of: "caption", "colgroup", "tbody", "tfoot", "thead"
-
Pop the current template insertion mode off the stack of template insertion modes.
Push "in table" onto the stack of template insertion modes so that it is the new current template insertion mode.
Switch the insertion mode to "in table", and reprocess the token.
- A start tag whose tag name is "col"
-
Pop the current template insertion mode off the stack of template insertion modes.
Push "in column group" onto the stack of template insertion modes so that it is the new current template insertion mode.
Switch the insertion mode to "in column group", and reprocess the token.
- A start tag whose tag name is "tr"
-
Pop the current template insertion mode off the stack of template insertion modes.
Push "in table body" onto the stack of template insertion modes so that it is the new current template insertion mode.
Switch the insertion mode to "in table body", and reprocess the token.
- A start tag whose tag name is one of: "td", "th"
-
Pop the current template insertion mode off the stack of template insertion modes.
Push "in row" onto the stack of template insertion modes so that it is the new current template insertion mode.
Switch the insertion mode to "in row", and reprocess the token.
- Any other start tag
-
Pop the current template insertion mode off the stack of template insertion modes.
Push "in body" onto the stack of template insertion modes so that it is the new current template insertion mode.
Switch the insertion mode to "in body", and reprocess the token.
- Any other end tag
- parse error. Ignore the token.
- An end-of-file token
-
If there is no
template
element on the stack of open elements, then stop parsing. (fragment case)Otherwise, this is a parse error.
Pop elements from the stack of open elements until a
template
element has been popped from the stack.Clear the list of active formatting elements up to the last marker.
Pop the current template insertion mode off the stack of template insertion modes.
Reset the insertion mode appropriately.
Reprocess the token.
8.2.5.4.19. The "after body" insertion mode
When the user agent is to apply the rules for the "after body" insertion mode, the user agent must handle the token as follows:
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
-
Process the token using the rules for the "in body" insertion mode.
- A comment token
-
Insert a comment as the last child of the first element in the stack of open elements (the
html
element). - A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "html"
-
Process the token using the rules for the "in body" insertion mode.
- An end tag whose tag name is "html"
-
If the parser was originally created as part of the HTML fragment parsing algorithm, this is a parse error; ignore the token. (fragment case)
Otherwise, switch the insertion mode to "after after body".
- An end-of-file token
- Stop parsing.
- Anything else
-
parse error. Switch the insertion mode to "in body" and reprocess the token.
8.2.5.4.20. The "in frameset" insertion mode
When the user agent is to apply the rules for the "in frameset" insertion mode, the user agent must handle the token as follows:
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- Insert the character.
- A comment token
- Insert a comment.
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "html"
-
Process the token using the rules for the "in body" insertion mode.
- A start tag whose tag name is "frameset"
- Insert an HTML element for the token.
- An end tag whose tag name is "frameset"
-
If the current node is the root
html
element, then this is a parse error; ignore the token. (fragment case)Otherwise, pop the current node from the stack of open elements.
If the parser was not originally created as part of the HTML fragment parsing algorithm (fragment case), and the current node is no longer a
frameset
element, then switch the insertion mode to "after frameset". - A start tag whose tag name is "frame"
-
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token’s self-closing flag, if it is set.
- A start tag whose tag name is "noframes"
-
Process the token using the rules for the "in head" insertion mode.
- An end-of-file token
-
If the current node is not the root
html
element, then this is a parse error.The current node can only be the root
html
element in the fragment case. - Anything else
- parse error. Ignore the token.
8.2.5.4.21. The "after frameset" insertion mode
When the user agent is to apply the rules for the "after frameset" insertion mode, the user agent must handle the token as follows:
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- Insert the character.
- A comment token
- Insert a comment.
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is "html"
-
Process the token using the rules for the "in body" insertion mode.
- An end tag whose tag name is "html"
-
Switch the insertion mode to "after after frameset".
- A start tag whose tag name is "noframes"
-
Process the token using the rules for the "in head" insertion mode.
- An end-of-file token
- Stop parsing.
- Anything else
- parse error. Ignore the token.
8.2.5.4.22. The "after after body" insertion mode
When the user agent is to apply the rules for the "after after body" insertion mode, the user agent must handle the token as follows:
- A comment token
- Insert a comment as the last child of the
Document
object. - A DOCTYPE token
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- A start tag whose tag name is "html"
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
-
Process the token using the rules for the "in body" insertion mode.
- An end-of-file token
- Stop parsing.
- Anything else
-
parse error. Switch the insertion mode to "in body" and reprocess the token.
8.2.5.4.23. The "after after frameset" insertion mode
When the user agent is to apply the rules for the "after after frameset" insertion mode, the user agent must handle the token as follows:
- A comment token
- Insert a comment as the last child of the
Document
object. - A DOCTYPE token
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- A start tag whose tag name is "html"
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
-
Process the token using the rules for the "in body" insertion mode.
- An end-of-file token
- Stop parsing.
- A start tag whose tag name is "noframes"
-
Process the token using the rules for the "in head" insertion mode.
- Anything else
- parse error. Ignore the token.
8.2.5.5. The rules for parsing tokens in foreign content
When the user agent is to apply the rules for parsing tokens in foreign content, the user agent must handle the token as follows:
- A character token that is U+0000 NULL
-
parse error. Insert a U+FFFD REPLACEMENT CHARACTER character.
- A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
- Any other character token
-
Set the frameset-ok flag to "not ok".
- A comment token
- A DOCTYPE token
- parse error. Ignore the token.
- A start tag whose tag name is one of: "b", "big", "blockquote", "body", "br", "center", "code", "dd", "div", "dl", "dt", "em", "embed", "h1", "h2", "h3", "h4", "h5", "h6", "head", "hr", "i", "img",
"li", "listing",
"menu", "meta", "nobr", "ol", "p", "pre", "ruby", "s", "small", "span", "strong", "strike", "sub",
"sup", "table", "tt", "u", "ul", "var"
- A start tag whose tag name is "font", if the token has any attributes named "color", "face", or "size"
-
If the parser was originally created for the HTML fragment parsing algorithm, then act as described in the "any other start tag" entry below. (fragment case)
Otherwise:
Pop an element from the stack of open elements, and then keep popping more elements from the stack of open elements until the current node is a MathML text integration point, an HTML integration point, or an element in the HTML namespace.
Then, reprocess the token.
- Any other start tag
-
If the adjusted current node is an element in the MathML namespace, adjust MathML attributes for the token. (This fixes the case of MathML attributes that are not all lowercase.)
If the adjusted current node is an element in the SVG namespace, and the token’s tag name is one of the ones in the first column of the following table, change the tag name to the name given in the corresponding cell in the second column. (This fixes the case of SVG elements that are not all lowercase.)
Tag name Element name altglyph
altGlyph
altglyphdef
altGlyphDef
altglyphitem
altGlyphItem
animatecolor
animateColor
animatemotion
animateMotion
animatetransform
animateTransform
clippath
clipPath
feblend
feBlend
fecolormatrix
feColorMatrix
fecomponenttransfer
feComponentTransfer
fecomposite
feComposite
feconvolvematrix
feConvolveMatrix
fediffuselighting
feDiffuseLighting
fedisplacementmap
feDisplacementMap
fedistantlight
feDistantLight
fedropshadow
feDropShadow
feflood
feFlood
fefunca
feFuncA
fefuncb
feFuncB
fefuncg
feFuncG
fefuncr
feFuncR
fegaussianblur
feGaussianBlur
feimage
feImage
femerge
feMerge
femergenode
feMergeNode
femorphology
feMorphology
feoffset
feOffset
fepointlight
fePointLight
fespecularlighting
feSpecularLighting
fespotlight
feSpotLight
fetile
feTile
feturbulence
feTurbulence
foreignobject
foreignObject
glyphref
glyphRef
lineargradient
linearGradient
radialgradient
radialGradient
textpath
textPath
If the adjusted current node is an element in the SVG namespace, adjust SVG attributes for the token. (This fixes the case of SVG attributes that are not all lowercase.)
Adjust foreign attributes for the token. (This fixes the use of namespaced attributes, in particular XLink in SVG.)
Insert a foreign element for the token, in the same namespace as the adjusted current node.
If the token has its self-closing flag set, then run the appropriate steps from the following list:
- If the token’s tag name is "script", and the new current node is in the SVG namespace
-
Acknowledge the token’s self-closing flag, and then act as described in the steps for a "script" end tag below.
- Otherwise
-
Pop the current node off the stack of open elements and acknowledge the token’s self-closing flag.
- An end tag whose tag name is "script", if the current node is a
script
element in the SVG namespace -
Pop the current node off the stack of open elements.
Let the old insertion point have the same value as the current insertion point. Let the insertion point be just before the next input character.
Increment the parser’s script nesting level by one. Set the parser pause flag to true.
Process the
script
element according to the SVG rules, if the user agent supports SVG. [SVG11]Even if this causes new characters to be inserted into the tokenizer, the parser will not be executed reentrantly, since the parser pause flag is true.
Decrement the parser’s script nesting level by one. If the parser’s script nesting level is zero, then set the parser pause flag to false.
Let the insertion point have the value of the old insertion point. (In other words, restore the insertion point to its previous value. This value might be the "undefined" value.)
- Any other end tag
-
Run these steps:
- Initialize node to be the current node (the bottommost node of the stack).
- If node’s tag name, converted to ASCII lowercase, is not the same as the tag name of the token, then this is a parse error.
- Loop: If node is the topmost element in the stack of open elements, abort these steps. (fragment case)
- If node’s tag name, converted to ASCII lowercase, is the same as the tag name of the token, pop elements from the stack of open elements until node has been popped from the stack, and then abort these steps.
- Set node to the previous entry in the stack of open elements.
- If node is not an element in the HTML namespace, return to the step labeled loop.
- Otherwise, process the token according to the rules given in the section corresponding to the current insertion mode in HTML content.
8.2.6. The end
Once the user agent stops parsing the document, the user agent must run the following steps:
- Set the current document readiness to "
interactive
" and the insertion point to undefined. - Pop all the nodes off the stack of open elements.
-
If the list of scripts that will execute when the document has finished
parsing is not empty, run these substeps:
- Spin the event loop until the first
script
in the list of scripts that will execute when the document has finished parsing has its "ready to be parser-executed" flag set and the parser’sDocument
has no style sheet that is blocking scripts. - Execute the first
script
in the list of scripts that will execute when the document has finished parsing. - Remove the first
script
element from the list of scripts that will execute when the document has finished parsing (i.e., shift out the first entry in the list). - If the list of scripts that will execute when the document has finished parsing is still not empty, repeat these substeps again from substep 1.
- Spin the event loop until the first
- Queue a task to fire a simple event that bubbles named
DOMContentLoaded
at theDocument
. - Spin the event loop until the set of scripts that will execute as soon as possible and the list of scripts that will execute in order as soon as possible are empty.
- Spin the event loop until there is nothing that delays the load event in the
Document
. -
Queue a task to run the following substeps:
- Set the current document readiness to "
complete
". - Load event: If the
Document
is in a browsing context, fire a simple event namedload
at theDocument
’sWindow
object, with target override set to theDocument
object.
- Set the current document readiness to "
-
If the
Document
is in a browsing context, then queue a task to run the following substeps:- If the
Document
’s page showing flag is true, then abort this task (i.e., don’t fire the event below). - Set the
Document
’s page showing flag to true. - Fire a trusted event with the name
pageshow
at theWindow
object of theDocument
, with target override set to theDocument
object, using thePageTransitionEvent
interface, with thepersisted
attribute initialized to false. This event must not bubble, must not be cancelable, and has no default action.
- If the
- If the
Document
has any pending application cache download process tasks, then queue each such task in the order they were added to the list of pending application cache download process tasks, and then empty the list of pending application cache download process tasks. The task source for these tasks is the networking task source. - If the
Document
’s print when loaded flag is set, then run the printing steps. - The
Document
is now ready for post-load tasks. - Queue a task to mark the
Document
as completely loaded.
When the user agent is to abort a parser, it must run the following steps:
- Throw away any pending content in the input stream, and discard any future content that would have been added to it.
- Set the current document readiness to "
interactive
". - Pop all the nodes off the stack of open elements.
- Set the current document readiness to "
complete
".
Except where otherwise specified, the task source for the tasks mentioned in this section is the DOM manipulation task source.
8.2.7. Coercing an HTML DOM into an infoset
When an application uses an HTML parser in conjunction with an XML pipeline, it is
possible that the constructed DOM is not compatible with the XML tool chain in certain subtle
ways. For example, an XML toolchain might not be able to represent attributes with the name xmlns
, since they conflict with the Namespaces in XML syntax. There is also some
data that the HTML parser generates that isn’t included in the DOM itself. This
section specifies some rules for handling these issues.
If the XML API being used doesn’t support DOCTYPEs, the tool may drop DOCTYPEs altogether.
If the XML API doesn’t support attributes in no namespace that are named "xmlns
", attributes whose names start with "xmlns:
", or
attributes in the XMLNS namespace, then the tool may drop such attributes.
The tool may annotate the output with any namespace declarations required for proper operation.
If the XML API being used restricts the allowable characters in the local names of elements and attributes, then the tool may map all element and attribute local names that the API wouldn’t support to a set of names that are allowed, by replacing any character that isn’t supported with the uppercase letter U and the six digits of the character’s Unicode code point when expressed in hexadecimal, using digits 0-9 and capital letters A-F as the symbols, in increasing numeric order.
For example, the element name foo<bar
, which can be
output by the HTML parser, though it is neither a legal HTML element name nor a
well-formed XML element name, would be converted into fooU00003Cbar
, which is a well-formed XML element name (though it’s still not legal in HTML by any means).
As another example, consider the attribute xlink:href
.
Used on a MathML element, it becomes, after being adjusted, an attribute with a prefix "xlink
" and a local
name "href
". However, used on an HTML element, it becomes an attribute with
no prefix and the local name "xlink:href
", which is not a valid NCName, and
thus might not be accepted by an XML API. It could thus get converted, becoming "xlinkU00003Ahref
".
The resulting names from this conversion conveniently can’t clash with any attribute generated by the HTML parser, since those are all either lowercase or those listed in the adjust foreign attributes algorithm’s table.
If the XML API restricts comments from having two consecutive U+002D HYPHEN-MINUS characters (--), the tool may insert a single U+0020 SPACE character between any such offending characters.
If the XML API restricts comments from ending in a U+002D HYPHEN-MINUS character (-), the tool may insert a single U+0020 SPACE character at the end of such comments.
If the XML API restricts allowed characters in character data, attribute values, or comments, the tool may replace any U+000C FORM FEED (FF) character with a U+0020 SPACE character, and any other literal non-XML character with a U+FFFD REPLACEMENT CHARACTER.
If the tool has no way to convey out-of-band information, then the tool may drop the following information:
- Whether the document is set to no-quirks mode, limited-quirks mode, or quirks mode
- The association between form controls and forms that aren’t their nearest
form
element ancestor (use of theform
element pointer in the parser) - The template contents of any
template
elements.
The mutations allowed by this section apply after the HTML
parser’s rules have been applied. For example, a <a::>
start tag
will be closed by a </a::>
end tag, and never by a </aU00003AU00003A>
end tag, even if the user agent is using the rules above to
then generate an actual element in the DOM with the name aU00003AU00003A
for
that start tag.
8.2.8. An introduction to error handling and strange cases in the parser
This section is non-normative.
This section examines some erroneous markup and discusses how the HTML parser handles these cases.
8.2.8.1. Misnested tags: <b><i></b></i>
This section is non-normative.
The most-often discussed example of erroneous markup is as follows:
<p>1<b>2<i>3</b>4</i>5</p>
The parsing of this markup is straightforward up to the "3". At this point, the DOM looks like this:
Here, the stack of open elements has five elements on it: html
, body
, p
, b
, and i
. The list of active
formatting elements just has two: b
and i
. The insertion
mode is "in body".
Upon receiving the end tag token with the tag name "b", the "adoption
agency algorithm" is invoked. This is a simple case, in that the formatting
element is the b
element, and there is no furthest block.
Thus, the stack of open elements ends up with just three elements: html
, body
, and p
, while the list of active formatting elements has just one: i
. The DOM tree is unmodified at this point.
The next token is a character ("4"), triggers the reconstruction of the active formatting elements, in this case just
the i
element. A new i
element is thus created for the "4" Text
node. After the end tag token for the "i" is also received, and the "5" Text
node is inserted, the DOM looks as follows:
8.2.8.2. Misnested tags: <b><p></b></p>
This section is non-normative.
A case similar to the previous one is the following:
<b>1<p>2</b>3</p>
Up to the "2" the parsing here is straightforward:
The interesting part is when the end tag token with the tag name "b" is parsed.
Before that token is seen, the stack of open elements has four elements on it: html
, body
, b
, and p
. The list of active
formatting elements just has the one: b
. The insertion mode is
"in body".
Upon receiving the end tag token with the tag name "b", the "adoption
agency algorithm" is invoked, as in the previous example. However, in this case, there is a furthest block, namely the p
element. Thus, this
time the adoption agency algorithm isn’t skipped over.
The common ancestor is the body
element. A conceptual
"bookmark" marks the position of the b
in the list of active formatting
elements, but since that list has only one element in it, the bookmark won’t have much
effect.
As the algorithm progresses, node ends up set to the formatting element
(b
), and last node ends up set to the furthest
block (p
).
The last node gets appended (moved) to the common ancestor, so that the DOM looks like:
A new b
element is created, and the children of the p
element are
moved to it:
Finally, the new b
element is appended to the p
element, so that the
DOM looks like:
The b
element is removed from the list of active formatting elements and the stack of open elements, so that when the "3" is parsed, it is appended to the p
element:
8.2.8.3. Unexpected markup in tables
This section is non-normative.
Error handling in tables is, for historical reasons, especially strange. For example, consider the following markup:
<table><b><tr><td>aaa</td></tr>bbb</table>ccc
The highlighted b
element start tag is not allowed directly inside a table like
that, and the parser handles this case by placing the element before the table. (This is
called foster parenting.) This can be seen by examining the DOM tree
as it stands just after the table
element’s start tag has been seen:
...and then immediately after the b
element start tag has been seen:
At this point, the stack of open elements has on it the elements html
, body
, table
, and b
(in that order,
despite the resulting DOM tree); the list of active formatting elements just has the b
element in it; and the insertion mode is "in table".
The tr
start tag causes the b
element to be popped off the stack and
a tbody
start tag to be implied; the tbody
and tr
elements
are then handled in a rather straight-forward manner, taking the parser through the "in table body" and "in row" insertion modes, after which the DOM looks as follows:
Here, the stack of open elements has on it the elements html
, body
, table
, tbody
, and tr
; the list of
active formatting elements still has the b
element in it; and the insertion mode is "in row".
The td
element start tag token, after putting a td
element on the
tree, puts a marker on the list of active
formatting elements (it also switches to the "in
cell" insertion mode).
The marker means that when the "aaa" character
tokens are seen, no b
element is created to hold the resulting Text
node:
The end tags are handled in a straight-forward manner; after handling them, the stack of
open elements has on it the elements html
, body
, table
, and tbody
; the list of active formatting elements still has the b
element in it (the marker having been removed by the "td" end tag token); and the insertion mode is "in table body".
Thus it is that the "bbb" character tokens are found. These trigger the "in table text" insertion mode to be used (with the original
insertion mode set to "in table body").
The character tokens are collected, and when the next token (the table
element end
tag) is seen, they are processed as a group. Since they are not all spaces, they are handled as
per the "anything else" rules in the "in table"
insertion mode, which defer to the "in body"
insertion mode but with foster parenting.
When the active formatting elements
are reconstructed, a b
element is created and foster parented, and then the "bbb" Text
node is appended to it:
The stack of open elements has on it the elements html
, body
, table
, tbody
, and the new b
(again, note
that this doesn’t match the resulting tree!); the list of active formatting elements has the new b
element in it; and the insertion mode is still "in table body".
Had the character tokens been only space characters instead of "bbb", then those space characters would just be
appended to the tbody
element.
Finally, the table
is closed by a "table" end tag. This pops all the nodes from
the stack of open elements up to and including the table
element, but it
doesn’t affect the list of active formatting elements, so the "ccc" character tokens
after the table result in yet another b
element being created, this time after the
table:
8.2.8.4. Scripts that modify the page as it is being parsed
This section is non-normative.
Consider the following markup, which for this example we will assume is the document with URL https://example.com/inner
, being rendered as the content of
an iframe
in another document with the URL https://example.com/outer
:
<div id=a> <script> var div = document.getElementById("a"); parent.document.body.appendChild(div); </script> <script> alert(document.URL); </script> </div> <script> alert(document.URL); </script>
Up to the first "script" end tag, before the script is parsed, the result is relatively straightforward:
After the script is parsed, though, the div
element and its child script
element are gone:
They are, at this point, in the Document
of the aforementioned outer browsing context. However, the stack of open elements still contains
the div
element.
Thus, when the second script
element is parsed, it is inserted into the outer Document
object.
Those parsed into different Document
s than the one the parser was created for do
not execute, so the first alert does not show.
Once the div
element’s end tag is parsed, the div
element is popped
off the stack, and so the next script
element is in the inner Document
:
This script does execute, resulting in an alert that says "https://example.com/inner".
8.2.8.5. The execution of scripts that are moving across multiple documents
This section is non-normative.
Elaborating on the example in the previous section, consider the case where the second script
element is an external script (i.e., one with a src
attribute). Since the element was not in the parser’s Document
when it was created, that external script is not even downloaded.
In a case where a script
element with a src
attribute is parsed normally into its parser’s Document
, but while the external
script is being downloaded, the element is moved to another document, the script continues to
download, but does not execute.
In general, moving script
elements between Document
s is
considered a bad practice.
8.2.8.6. Unclosed formatting elements
This section is non-normative.
The following markup shows how nested formatting elements (such as b
) get
collected and continue to be applied even as the elements they are contained in are closed, but
that excessive duplicates are thrown away.
<!DOCTYPE html> <p><b class=x><b class=x><b><b class=x><b class=x><b>X <p>X <p><b><b class=x><b>X <p></b></b></b></b></b></b>X
The resulting DOM tree is as follows:
- DOCTYPE:
html
-
html
Note how the second p
element in the markup has no explicit b
elements, but in the resulting DOM, up to three of each kind of formatting element (in this case
three b
elements with the class attribute, and two unadorned b
elements)
get reconstructed before the element’s "X".
Also note how this means that in the final paragraph only six b
end tags are
needed to completely clear the list of active formatting elements, even though nine b
start
tags have been seen up to this point.
8.3. Serializing HTML fragments
The following steps form the HTML fragment serialization algorithm. The algorithm
takes as input a DOM Element
, Document
, or DocumentFragment
referred to as the node, and either returns a string.
This algorithm serializes the children of the node being serialized, not the node itself.
- Let s be a string, and initialize it to the empty string.
- If the node is a
template
element, then let the node instead be thetemplate
element’s template contents (aDocumentFragment
node). -
For each child node of the node, in tree order, run the following steps:
- Let current node be the child node being processed.
-
Append the appropriate string from the following list to s:
- If current node is an
Element
-
If current node is an element in the HTML namespace, the MathML namespace, or the SVG namespace, then let tagname be current node’s local name. Otherwise, let tagname be current node’s qualified name.
Append a U+003C LESS-THAN SIGN character (<), followed by tagname.
For html elements created by the HTML parser or
Document.createElement()
, tagname will be lowercase.For each attribute that the element has, append a U+0020 SPACE character, the attribute’s serialized name as described below, a U+003D EQUALS SIGN character (=), a U+0022 QUOTATION MARK character ("), the attribute’s value, escaped as described below in attribute mode, and a second U+0022 QUOTATION MARK character (").
An attribute’s serialized name for the purposes of the previous paragraph must be determined as follows:
- If the attribute has no namespace
-
The attribute’s serialized name is the attribute’s local name.
For attributes on html elements set by the HTML parser or by
Element.setAttribute()
, the local name will be lowercase. - If the attribute is in the XML namespace
- The attribute’s serialized name is the string "
xml:
" followed by the attribute’s local name. - If the attribute is in the XMLNS namespace and the attribute’s local name
is
xmlns
- The attribute’s serialized name is the string "
xmlns
". - If the attribute is in the XMLNS namespace and the attribute’s local name
is not
xmlns
- The attribute’s serialized name is the string "
xmlns:
" followed by the attribute’s local name. - If the attribute is in the XLink namespace
- The attribute’s serialized name is the string "
xlink:
" followed by the attribute’s local name. - If the attribute is in some other namespace
- The attribute’s serialized name is the attribute’s qualified name.
While the exact order of attributes is user agent-defined, and may depend on factors such as the order that the attributes were given in the original markup, the sort order must be stable, such that consecutive invocations of this algorithm serialize an element’s attributes in the same order.
Append a U+003E GREATER-THAN SIGN character (>).
If current node is an
area
,base
,basefont
,bgsound
,br
,col
,embed
,frame
,hr
,img
,input
,keygen
,link
,menuitem
,meta
,param
,source
,track
orwbr
element, then continue on to the next child node at this point.If current node is a
pre
,textarea
, orlisting
element, and the first child node of the element, if any, is aText
node whose character data has as its first character a U+000A LINE FEED (LF) character, then append a U+000A LINE FEED (LF) character.Append the value of running the HTML fragment serialization algorithm on the current node element (thus recursing into this algorithm for that element), followed by a U+003C LESS-THAN SIGN character (<), a U+002F SOLIDUS character (/), tagname again, and finally a U+003E GREATER-THAN SIGN character (>).
- If current node is a
Text
node -
If the parent of current node is a
style
,script
,xmp
,iframe
,noembed
,noframes
, orplaintext
element, or if the parent of current node is anoscript
element and scripting is enabled for the node, then append the value of current node’sdata
IDL attribute literally.Otherwise, append the value of current node’s
data
IDL attribute, escaped as described below. - If current node is a
Comment
-
Append the literal string "
<!--
" (U+003C LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS), followed by the value of current node’sdata
IDL attribute, followed by the literal string "-->
" (U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS, U+003E GREATER-THAN SIGN). - If current node is a
ProcessingInstruction
-
Append the literal string "
<?
" (U+003C LESS-THAN SIGN, U+003F QUESTION MARK), followed by the value of current node’starget
IDL attribute, followed by a single U+0020 SPACE character, followed by the value of current node’sdata
IDL attribute, followed by a single U+003E GREATER-THAN SIGN character (>). - If current node is a
DocumentType
-
Append the literal string "
<!DOCTYPE
" (U+003C LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+0044 LATIN CAPITAL LETTER D, U+004F LATIN CAPITAL LETTER O, U+0043 LATIN CAPITAL LETTER C, U+0054 LATIN CAPITAL LETTER T, U+0059 LATIN CAPITAL LETTER Y, U+0050 LATIN CAPITAL LETTER P, U+0045 LATIN CAPITAL LETTER E), followed by a space (U+0020 SPACE), followed by the value of current node’sname
IDL attribute, followed by the literal string ">
" (U+003E GREATER-THAN SIGN).
- If current node is an
- The result of the algorithm is the string s.
It is possible that the output of this algorithm, if parsed with an HTML parser, will not return the original tree structure.
textarea
element to which a Comment
node
has been appended is serialized and the output is then reparsed, the comment will end up being
displayed in the text field. Similarly, if, as a result of DOM manipulation, an element contains
a comment that contains the literal string "-->
", then when the result
of serializing the element is parsed, the comment will be truncated at that point and the rest of
the comment will be interpreted as markup. More examples would be making a script
element contain a Text
node with the text string "</script>
", or
having a p
element that contains a ul
element (as the ul
element’s start tag would imply the end tag for the p
).
This can enable cross-site scripting attacks. An example of this would be a page that lets the
user enter some font family names that are then inserted into a CSS style
block via
the DOM and which then uses the innerHTML
IDL attribute to get
the HTML serialization of that style
element: if the user enters
"</style><script>attack</script>
" as a font family name, innerHTML
will return markup that, if parsed in a different context,
would contain a script
node, even though no script
node existed in the
original DOM.
Escaping a string (for the purposes of the algorithm above) consists of running the following steps:
- Replace any occurrence of the "
&
" character by the string "&
". - Replace any occurrences of the U+00A0 NO-BREAK SPACE character by the string "
". - If the algorithm was invoked in the attribute mode, replace any occurrences of the
"
"
" character by the string ""
". - If the algorithm was not invoked in the attribute mode, replace any
occurrences of the "
<
" character by the string "<
", and any occurrences of the ">
" character by the string ">
".
8.4. Parsing HTML fragments
The following steps form the HTML fragment parsing algorithm.
The algorithm takes as input an Element
node, referred to as the context element,
which gives the context for the parser, as well as input, a string to parse, and
returns a list of zero or more nodes.
Parts marked fragment case in algorithms in the parser section are parts that only occur if the parser was created for the purposes of this algorithm. The algorithms have been annotated with such markings for informational purposes only; such markings have no normative weight. If it is possible for a condition described as a fragment case to occur even when the parser wasn’t created for the purposes of handling this algorithm, then that is an error in the specification.
-
Create a new
Document
node, and mark it as being an HTML document. -
If the node document of the context element is in quirks mode, then let the
Document
be in quirks mode. Otherwise, the node document of the context element is in limited-quirks mode, then let theDocument
be in limited-quirks mode. Otherwise, leave theDocument
in no-quirks mode. -
Create a new HTML parser, and associate it with the just created
Document
node. -
Set the state of the HTML parser’s tokenization stage as follows:
- If it is a
title
ortextarea
element - Switch the tokenizer to the §8.2.4.3 RCDATA state.
- If it is a
style
,xmp
,iframe
,noembed
, ornoframes
element - Switch the tokenizer to the §8.2.4.5 RAWTEXT state.
- If it is a
script
element - Switch the tokenizer to the §8.2.4.6 Script data state.
- If it is a
noscript
element - If the scripting flag is enabled, switch the tokenizer to the §8.2.4.5 RAWTEXT state. Otherwise, leave the tokenizer in the §8.2.4.1 Data state.
- If it is a
plaintext
element - Switch the tokenizer to the §8.2.4.7 PLAINTEXT state.
- Otherwise
- Leave the tokenizer in the §8.2.4.1 Data state.
For performance reasons, an implementation that does not report errors and that uses the actual state machine described in this specification directly could use the PLAINTEXT state instead of the RAWTEXT and script data states where those are mentioned in the list above. Except for rules regarding parse errors, they are equivalent, since there is no appropriate end tag token in the fragment case, yet they involve far fewer state transitions.
- If it is a
-
Let root be a new
html
element with no attributes. -
Append the element root to the
Document
node created above. -
Set up the parser’s stack of open elements so that it contains just the single element root.
-
If the context element is a
template
element, push "in template" onto the stack of template insertion modes so that it is the new current template insertion mode. -
Create a start tag token whose name is the local name of context and whose attributes are the attributes of context.
Let this start tag token be the start tag token of the context node, e.g., for the purposes of determining if it is an HTML integration point.
-
Reset the parser’s insertion mode appropriately.
The parser will reference the context element as part of that algorithm.
-
Set the parser’s
form
element pointer to the nearest node to the context element that is aform
element (going straight up the ancestor chain, and including the element itself, if it is aform
element), if any. (If there is no suchform
element, theform
element pointer keeps its initial value, null.) -
Place the input into the input stream for the HTML parser just created. The encoding confidence is irrelevant.
-
Start the parser and let it run until it has consumed all the characters just inserted into the input stream.
-
Return the child nodes of root, in tree order.
8.5. Named character references
This table lists the character reference names that are supported by HTML, and the code points to which they refer. It is referenced by the previous sections.
Name | Character(s) | Glyph |
---|---|---|
Aacute;
| U+000C1 | Á |
Aacute
| U+000C1 | Á |
aacute;
| U+000E1 | á |
aacute
| U+000E1 | á |
Abreve;
| U+00102 | Ă |
abreve;
| U+00103 | ă |
ac;
| U+0223E | ∾ |
acd;
| U+0223F | ∿ |
acE;
| U+0223E U+00333 | ∾̳ |
Acirc;
| U+000C2 | Â |
Acirc
| U+000C2 | Â |
acirc;
| U+000E2 | â |
acirc
| U+000E2 | â |
acute;
| U+000B4 | ´ |
acute
| U+000B4 | ´ |
Acy;
| U+00410 | А |
acy;
| U+00430 | а |
AElig;
| U+000C6 | Æ |
AElig
| U+000C6 | Æ |
aelig;
| U+000E6 | æ |
aelig
| U+000E6 | æ |
af;
| U+02061 | |
Afr;
| U+1D504 | 𝔄 |
afr;
| U+1D51E | 𝔞 |
Agrave;
| U+000C0 | À |
Agrave
| U+000C0 | À |
agrave;
| U+000E0 | à |
agrave
| U+000E0 | à |
alefsym;
| U+02135 | ℵ |
aleph;
| U+02135 | ℵ |
Alpha;
| U+00391 | Α |
alpha;
| U+003B1 | α |
Amacr;
| U+00100 | Ā |
amacr;
| U+00101 | ā |
amalg;
| U+02A3F | ⨿ |
AMP;
| U+00026 | & |
AMP
| U+00026 | & |
amp;
| U+00026 | & |
amp
| U+00026 | & |
And;
| U+02A53 | ⩓ |
and;
| U+02227 | ∧ |
andand;
| U+02A55 | ⩕ |
andd;
| U+02A5C | ⩜ |
andslope;
| U+02A58 | ⩘ |
andv;
| U+02A5A | ⩚ |
ang;
| U+02220 | ∠ |
ange;
| U+029A4 | ⦤ |
angle;
| U+02220 | ∠ |
angmsd;
| U+02221 | ∡ |
angmsdaa;
| U+029A8 | ⦨ |
angmsdab;
| U+029A9 | ⦩ |
angmsdac;
| U+029AA | ⦪ |
angmsdad;
| U+029AB | ⦫ |
angmsdae;
| U+029AC | ⦬ |
angmsdaf;
| U+029AD | ⦭ |
angmsdag;
| U+029AE | ⦮ |
angmsdah;
| U+029AF | ⦯ |
angrt;
| U+0221F | ∟ |
angrtvb;
| U+022BE | ⊾ |
angrtvbd;
| U+0299D | ⦝ |
angsph;
| U+02222 | ∢ |
angst;
| U+000C5 | Å |
angzarr;
| U+0237C | ⍼ |
Aogon;
| U+00104 | Ą |
aogon;
| U+00105 | ą |
Aopf;
| U+1D538 | 𝔸 |
aopf;
| U+1D552 | 𝕒 |
ap;
| U+02248 | ≈ |
apacir;
| U+02A6F | ⩯ |
apE;
| U+02A70 | ⩰ |
ape;
| U+0224A | ≊ |
apid;
| U+0224B | ≋ |
apos;
| U+00027 | ' |
ApplyFunction;
| U+02061 | |
approx;
| U+02248 | ≈ |
approxeq;
| U+0224A | ≊ |
Aring;
| U+000C5 | Å |
Aring
| U+000C5 | Å |
aring;
| U+000E5 | å |
aring
| U+000E5 | å |
Ascr;
| U+1D49C | 𝒜 |
ascr;
| U+1D4B6 | 𝒶 |
Assign;
| U+02254 | ≔ |
ast;
| U+0002A | * |
asymp;
| U+02248 | ≈ |
asympeq;
| U+0224D | ≍ |
Atilde;
| U+000C3 | Ã |
Atilde
| U+000C3 | Ã |
atilde;
| U+000E3 | ã |
atilde
| U+000E3 | ã |
Auml;
| U+000C4 | Ä |
Auml
| U+000C4 | Ä |
auml;
| U+000E4 | ä |
auml
| U+000E4 | ä |
awconint;
| U+02233 | ∳ |
awint;
| U+02A11 | ⨑ |
backcong;
| U+0224C | ≌ |
backepsilon;
| U+003F6 | ϶ |
backprime;
| U+02035 | ‵ |
backsim;
| U+0223D | ∽ |
backsimeq;
| U+022CD | ⋍ |
Backslash;
| U+02216 | ∖ |
Barv;
| U+02AE7 | ⫧ |
barvee;
| U+022BD | ⊽ |
Barwed;
| U+02306 | ⌆ |
barwed;
| U+02305 | ⌅ |
barwedge;
| U+02305 | ⌅ |
bbrk;
| U+023B5 | ⎵ |
bbrktbrk;
| U+023B6 | ⎶ |
bcong;
| U+0224C | ≌ |
Bcy;
| U+00411 | Б |
bcy;
| U+00431 | б |
bdquo;
| U+0201E | „ |
becaus;
| U+02235 | ∵ |
Because;
| U+02235 | ∵ |
because;
| U+02235 | ∵ |
bemptyv;
| U+029B0 | ⦰ |
bepsi;
| U+003F6 | ϶ |
bernou;
| U+0212C | ℬ |
Bernoullis;
| U+0212C | ℬ |
Beta;
| U+00392 | Β |
beta;
| U+003B2 | β |
beth;
| U+02136 | ℶ |
between;
| U+0226C | ≬ |
Bfr;
| U+1D505 | 𝔅 |
bfr;
| U+1D51F | 𝔟 |
bigcap;
| U+022C2 | ⋂ |
bigcirc;
| U+025EF | ◯ |
bigcup;
| U+022C3 | ⋃ |
bigodot;
| U+02A00 | ⨀ |
bigoplus;
| U+02A01 | ⨁ |
bigotimes;
| U+02A02 | ⨂ |
bigsqcup;
| U+02A06 | ⨆ |
bigstar;
| U+02605 | ★ |
bigtriangledown;
| U+025BD | ▽ |
bigtriangleup;
| U+025B3 | △ |
biguplus;
| U+02A04 | ⨄ |
bigvee;
| U+022C1 | ⋁ |
bigwedge;
| U+022C0 | ⋀ |
bkarow;
| U+0290D | ⤍ |
blacklozenge;
| U+029EB | ⧫ |
blacksquare;
| U+025AA | ▪ |
blacktriangle;
| U+025B4 | ▴ |
blacktriangledown;
| U+025BE | ▾ |
blacktriangleleft;
| U+025C2 | ◂ |
blacktriangleright;
| U+025B8 | ▸ |
blank;
| U+02423 | ␣ |
blk12;
| U+02592 | ▒ |
blk14;
| U+02591 | ░ |
blk34;
| U+02593 | ▓ |
block;
| U+02588 | █ |
bne;
| U+0003D U+020E5 | =⃥ |
bnequiv;
| U+02261 U+020E5 | ≡⃥ |
bNot;
| U+02AED | ⫭ |
bnot;
| U+02310 | ⌐ |
Bopf;
| U+1D539 | 𝔹 |
bopf;
| U+1D553 | 𝕓 |
bot;
| U+022A5 | ⊥ |
bottom;
| U+022A5 | ⊥ |
bowtie;
| U+022C8 | ⋈ |
boxbox;
| U+029C9 | ⧉ |
boxDL;
| U+02557 | ╗ |
boxDl;
| U+02556 | ╖ |
boxdL;
| U+02555 | ╕ |
boxdl;
| U+02510 | ┐ |
boxDR;
| U+02554 | ╔ |
boxDr;
| U+02553 | ╓ |
boxdR;
| U+02552 | ╒ |
boxdr;
| U+0250C | ┌ |
boxH;
| U+02550 | ═ |
boxh;
| U+02500 | ─ |
boxHD;
| U+02566 | ╦ |
boxHd;
| U+02564 | ╤ |
boxhD;
| U+02565 | ╥ |
boxhd;
| U+0252C | ┬ |
boxHU;
| U+02569 | ╩ |
boxHu;
| U+02567 | ╧ |
boxhU;
| U+02568 | ╨ |
boxhu;
| U+02534 | ┴ |
boxminus;
| U+0229F | ⊟ |
boxplus;
| U+0229E | ⊞ |
boxtimes;
| U+022A0 | ⊠ |
boxUL;
| U+0255D | ╝ |
boxUl;
| U+0255C | ╜ |
boxuL;
| U+0255B | ╛ |
boxul;
| U+02518 | ┘ |
boxUR;
| U+0255A | ╚ |
boxUr;
| U+02559 | ╙ |
boxuR;
| U+02558 | ╘ |
boxur;
| U+02514 | └ |
boxV;
| U+02551 | ║ |
boxv;
| U+02502 | │ |
boxVH;
| U+0256C | ╬ |
boxVh;
| U+0256B | ╫ |
boxvH;
| U+0256A | ╪ |
boxvh;
| U+0253C | ┼ |
boxVL;
| U+02563 | ╣ |
boxVl;
| U+02562 | ╢ |
boxvL;
| U+02561 | ╡ |
boxvl;
| U+02524 | ┤ |
boxVR;
| U+02560 | ╠ |
boxVr;
| U+0255F | ╟ |
boxvR;
| U+0255E | ╞ |
boxvr;
| U+0251C | ├ |
bprime;
| U+02035 | ‵ |
Breve;
| U+002D8 | ˘ |
breve;
| U+002D8 | ˘ |
brvbar;
| U+000A6 | ¦ |
brvbar
| U+000A6 | ¦ |
Bscr;
| U+0212C | ℬ |
bscr;
| U+1D4B7 | 𝒷 |
bsemi;
| U+0204F | ⁏ |
bsim;
| U+0223D | ∽ |
bsime;
| U+022CD | ⋍ |
bsol;
| U+0005C | \ |
bsolb;
| U+029C5 | ⧅ |
bsolhsub;
| U+027C8 | ⟈ |
bull;
| U+02022 | • |
bullet;
| U+02022 | • |
bump;
| U+0224E | ≎ |
bumpE;
| U+02AAE | ⪮ |
bumpe;
| U+0224F | ≏ |
Bumpeq;
| U+0224E | ≎ |
bumpeq;
| U+0224F | ≏ |
Cacute;
| U+00106 | Ć |
cacute;
| U+00107 | ć |
Cap;
| U+022D2 | ⋒ |
cap;
| U+02229 | ∩ |
capand;
| U+02A44 | ⩄ |
capbrcup;
| U+02A49 | ⩉ |
capcap;
| U+02A4B | ⩋ |
capcup;
| U+02A47 | ⩇ |
capdot;
| U+02A40 | ⩀ |
CapitalDifferentialD;
| U+02145 | ⅅ |
caps;
| U+02229 U+0FE00 | ∩︀ |
caret;
| U+02041 | ⁁ |
caron;
| U+002C7 | ˇ |
Cayleys;
| U+0212D | ℭ |
ccaps;
| U+02A4D | ⩍ |
Ccaron;
| U+0010C | Č |
ccaron;
| U+0010D | č |
Ccedil;
| U+000C7 | Ç |
Ccedil
| U+000C7 | Ç |
ccedil;
| U+000E7 | ç |
ccedil
| U+000E7 | ç |
Ccirc;
| U+00108 | Ĉ |
ccirc;
| U+00109 | ĉ |
Cconint;
| U+02230 | ∰ |
ccups;
| U+02A4C | ⩌ |
ccupssm;
| U+02A50 | ⩐ |
Cdot;
| U+0010A | Ċ |
cdot;
| U+0010B | ċ |
cedil;
| U+000B8 | ¸ |
cedil
| U+000B8 | ¸ |
Cedilla;
| U+000B8 | ¸ |
cemptyv;
| U+029B2 | ⦲ |
cent;
| U+000A2 | ¢ |
cent
| U+000A2 | ¢ |
CenterDot;
| U+000B7 | · |
centerdot;
| U+000B7 | · |
Cfr;
| U+0212D | ℭ |
cfr;
| U+1D520 | 𝔠 |
CHcy;
| U+00427 | Ч |
chcy;
| U+00447 | ч |
check;
| U+02713 | ✓ |
checkmark;
| U+02713 | ✓ |
Chi;
| U+003A7 | Χ |
chi;
| U+003C7 | χ |
cir;
| U+025CB | ○ |
circ;
| U+002C6 | ˆ |
circeq;
| U+02257 | ≗ |
circlearrowleft;
| U+021BA | ↺ |
circlearrowright;
| U+021BB | ↻ |
circledast;
| U+0229B | ⊛ |
circledcirc;
| U+0229A | ⊚ |
circleddash;
| U+0229D | ⊝ |
CircleDot;
| U+02299 | ⊙ |
circledR;
| U+000AE | ® |
circledS;
| U+024C8 | Ⓢ |
CircleMinus;
| U+02296 | ⊖ |
CirclePlus;
| U+02295 | ⊕ |
CircleTimes;
| U+02297 | ⊗ |
cirE;
| U+029C3 | ⧃ |
cire;
| U+02257 | ≗ |
cirfnint;
| U+02A10 | ⨐ |
cirmid;
| U+02AEF | ⫯ |
cirscir;
| U+029C2 | ⧂ |
ClockwiseContourIntegral;
| U+02232 | ∲ |
CloseCurlyDoubleQuote;
| U+0201D | ” |
CloseCurlyQuote;
| U+02019 | ’ |
clubs;
| U+02663 | ♣ |
clubsuit;
| U+02663 | ♣ |
Colon;
| U+02237 | ∷ |
colon;
| U+0003A | : |
Colone;
| U+02A74 | ⩴ |
colone;
| U+02254 | ≔ |
coloneq;
| U+02254 | ≔ |
comma;
| U+0002C | , |
commat;
| U+00040 | @ |
comp;
| U+02201 | ∁ |
compfn;
| U+02218 | ∘ |
complement;
| U+02201 | ∁ |
complexes;
| U+02102 | ℂ |
cong;
| U+02245 | ≅ |
congdot;
| U+02A6D | ⩭ |
Congruent;
| U+02261 | ≡ |
Conint;
| U+0222F | ∯ |
conint;
| U+0222E | ∮ |
ContourIntegral;
| U+0222E | ∮ |
Copf;
| U+02102 | ℂ |
copf;
| U+1D554 | 𝕔 |
coprod;
| U+02210 | ∐ |
Coproduct;
| U+02210 | ∐ |
COPY;
| U+000A9 | © |
COPY
| U+000A9 | © |
copy;
| U+000A9 | © |
copy
| U+000A9 | © |
copysr;
| U+02117 | ℗ |
CounterClockwiseContourIntegral;
| U+02233 | ∳ |
crarr;
| U+021B5 | ↵ |
Cross;
| U+02A2F | ⨯ |
cross;
| U+02717 | ✗ |
Cscr;
| U+1D49E | 𝒞 |
cscr;
| U+1D4B8 | 𝒸 |
csub;
| U+02ACF | ⫏ |
csube;
| U+02AD1 | ⫑ |
csup;
| U+02AD0 | ⫐ |
csupe;
| U+02AD2 | ⫒ |
ctdot;
| U+022EF | ⋯ |
cudarrl;
| U+02938 | ⤸ |
cudarrr;
| U+02935 | ⤵ |
cuepr;
| U+022DE | ⋞ |
cuesc;
| U+022DF | ⋟ |
cularr;
| U+021B6 | ↶ |
cularrp;
| U+0293D | ⤽ |
Cup;
| U+022D3 | ⋓ |
cup;
| U+0222A | ∪ |
cupbrcap;
| U+02A48 | ⩈ |
CupCap;
| U+0224D | ≍ |
cupcap;
| U+02A46 | ⩆ |
cupcup;
| U+02A4A | ⩊ |
cupdot;
| U+0228D | ⊍ |
cupor;
| U+02A45 | ⩅ |
cups;
| U+0222A U+0FE00 | ∪︀ |
curarr;
| U+021B7 | ↷ |
curarrm;
| U+0293C | ⤼ |
curlyeqprec;
| U+022DE | ⋞ |
curlyeqsucc;
| U+022DF | ⋟ |
curlyvee;
| U+022CE | ⋎ |
curlywedge;
| U+022CF | ⋏ |
curren;
| U+000A4 | ¤ |
curren
| U+000A4 | ¤ |
curvearrowleft;
| U+021B6 | ↶ |
curvearrowright;
| U+021B7 | ↷ |
cuvee;
| U+022CE | ⋎ |
cuwed;
| U+022CF | ⋏ |
cwconint;
| U+02232 | ∲ |
cwint;
| U+02231 | ∱ |
cylcty;
| U+0232D | ⌭ |
Dagger;
| U+02021 | ‡ |
dagger;
| U+02020 | † |
daleth;
| U+02138 | ℸ |
Darr;
| U+021A1 | ↡ |
dArr;
| U+021D3 | ⇓ |
darr;
| U+02193 | ↓ |
dash;
| U+02010 | ‐ |
Dashv;
| U+02AE4 | ⫤ |
dashv;
| U+022A3 | ⊣ |
dbkarow;
| U+0290F | ⤏ |
dblac;
| U+002DD | ˝ |
Dcaron;
| U+0010E | Ď |
dcaron;
| U+0010F | ď |
Dcy;
| U+00414 | Д |
dcy;
| U+00434 | д |
DD;
| U+02145 | ⅅ |
dd;
| U+02146 | ⅆ |
ddagger;
| U+02021 | ‡ |
ddarr;
| U+021CA | ⇊ |
DDotrahd;
| U+02911 | ⤑ |
ddotseq;
| U+02A77 | ⩷ |
deg;
| U+000B0 | ° |
deg
| U+000B0 | ° |
Del;
| U+02207 | ∇ |
Delta;
| U+00394 | Δ |
delta;
| U+003B4 | δ |
demptyv;
| U+029B1 | ⦱ |
dfisht;
| U+0297F | ⥿ |
Dfr;
| U+1D507 | 𝔇 |
dfr;
| U+1D521 | 𝔡 |
dHar;
| U+02965 | ⥥ |
dharl;
| U+021C3 | ⇃ |
dharr;
| U+021C2 | ⇂ |
DiacriticalAcute;
| U+000B4 | ´ |
DiacriticalDot;
| U+002D9 | ˙ |
DiacriticalDoubleAcute;
| U+002DD | ˝ |
DiacriticalGrave;
| U+00060 | ` |
DiacriticalTilde;
| U+002DC | ˜ |
diam;
| U+022C4 | ⋄ |
Diamond;
| U+022C4 | ⋄ |
diamond;
| U+022C4 | ⋄ |
diamondsuit;
| U+02666 | ♦ |
diams;
| U+02666 | ♦ |
die;
| U+000A8 | ¨ |
DifferentialD;
| U+02146 | ⅆ |
digamma;
| U+003DD | ϝ |
disin;
| U+022F2 | ⋲ |
div;
| U+000F7 | ÷ |
divide;
| U+000F7 | ÷ |
divide
| U+000F7 | ÷ |
divideontimes;
| U+022C7 | ⋇ |
divonx;
| U+022C7 | ⋇ |
DJcy;
| U+00402 | Ђ |
djcy;
| U+00452 | ђ |
dlcorn;
| U+0231E | ⌞ |
dlcrop;
| U+0230D | ⌍ |
dollar;
| U+00024 | $ |
Dopf;
| U+1D53B | 𝔻 |
dopf;
| U+1D555 | 𝕕 |
Dot;
| U+000A8 | ¨ |
dot;
| U+002D9 | ˙ |
DotDot;
| U+020DC | ◌⃜ |
doteq;
| U+02250 | ≐ |
doteqdot;
| U+02251 | ≑ |
DotEqual;
| U+02250 | ≐ |
dotminus;
| U+02238 | ∸ |
dotplus;
| U+02214 | ∔ |
dotsquare;
| U+022A1 | ⊡ |
doublebarwedge;
| U+02306 | ⌆ |
DoubleContourIntegral;
| U+0222F | ∯ |
DoubleDot;
| U+000A8 | ¨ |
DoubleDownArrow;
| U+021D3 | ⇓ |
DoubleLeftArrow;
| U+021D0 | ⇐ |
DoubleLeftRightArrow;
| U+021D4 | ⇔ |
DoubleLeftTee;
| U+02AE4 | ⫤ |
DoubleLongLeftArrow;
| U+027F8 | ⟸ |
DoubleLongLeftRightArrow;
| U+027FA | ⟺ |
DoubleLongRightArrow;
| U+027F9 | ⟹ |
DoubleRightArrow;
| U+021D2 | ⇒ |
DoubleRightTee;
| U+022A8 | ⊨ |
DoubleUpArrow;
| U+021D1 | ⇑ |
DoubleUpDownArrow;
| U+021D5 | ⇕ |
DoubleVerticalBar;
| U+02225 | ∥ |
DownArrow;
| U+02193 | ↓ |
Downarrow;
| U+021D3 | ⇓ |
downarrow;
| U+02193 | ↓ |
DownArrowBar;
| U+02913 | ⤓ |
DownArrowUpArrow;
| U+021F5 | ⇵ |
DownBreve;
| U+00311 | ◌̑ |
downdownarrows;
| U+021CA | ⇊ |
downharpoonleft;
| U+021C3 | ⇃ |
downharpoonright;
| U+021C2 | ⇂ |
DownLeftRightVector;
| U+02950 | ⥐ |
DownLeftTeeVector;
| U+0295E | ⥞ |
DownLeftVector;
| U+021BD | ↽ |
DownLeftVectorBar;
| U+02956 | ⥖ |
DownRightTeeVector;
| U+0295F | ⥟ |
DownRightVector;
| U+021C1 | ⇁ |
DownRightVectorBar;
| U+02957 | ⥗ |
DownTee;
| U+022A4 | ⊤ |
DownTeeArrow;
| U+021A7 | ↧ |
drbkarow;
| U+02910 | ⤐ |
drcorn;
| U+0231F | ⌟ |
drcrop;
| U+0230C | ⌌ |
Dscr;
| U+1D49F | 𝒟 |
dscr;
| U+1D4B9 | 𝒹 |
DScy;
| U+00405 | Ѕ |
dscy;
| U+00455 | ѕ |
dsol;
| U+029F6 | ⧶ |
Dstrok;
| U+00110 | Đ |
dstrok;
| U+00111 | đ |
dtdot;
| U+022F1 | ⋱ |
dtri;
| U+025BF | ▿ |
dtrif;
| U+025BE | ▾ |
duarr;
| U+021F5 | ⇵ |
duhar;
| U+0296F | ⥯ |
dwangle;
| U+029A6 | ⦦ |
DZcy;
| U+0040F | Џ |
dzcy;
| U+0045F | џ |
dzigrarr;
| U+027FF | ⟿ |
Eacute;
| U+000C9 | É |
Eacute
| U+000C9 | É |
eacute;
| U+000E9 | é |
eacute
| U+000E9 | é |
easter;
| U+02A6E | ⩮ |
Ecaron;
| U+0011A | Ě |
ecaron;
| U+0011B | ě |
ecir;
| U+02256 | ≖ |
Ecirc;
| U+000CA | Ê |
Ecirc
| U+000CA | Ê |
ecirc;
| U+000EA | ê |
ecirc
| U+000EA | ê |
ecolon;
| U+02255 | ≕ |
Ecy;
| U+0042D | Э |
ecy;
| U+0044D | э |
eDDot;
| U+02A77 | ⩷ |
Edot;
| U+00116 | Ė |
eDot;
| U+02251 | ≑ |
edot;
| U+00117 | ė |
ee;
| U+02147 | ⅇ |
efDot;
| U+02252 | ≒ |
Efr;
| U+1D508 | 𝔈 |
efr;
| U+1D522 | 𝔢 |
eg;
| U+02A9A | ⪚ |
Egrave;
| U+000C8 | È |
Egrave
| U+000C8 | È |
egrave;
| U+000E8 | è |
egrave
| U+000E8 | è |
egs;
| U+02A96 | ⪖ |
egsdot;
| U+02A98 | ⪘ |
el;
| U+02A99 | ⪙ |
Element;
| U+02208 | ∈ |
elinters;
| U+023E7 | ⏧ |
ell;
| U+02113 | ℓ |
els;
| U+02A95 | ⪕ |
elsdot;
| U+02A97 | ⪗ |
Emacr;
| U+00112 | Ē |
emacr;
| U+00113 | ē |
empty;
| U+02205 | ∅ |
emptyset;
| U+02205 | ∅ |
EmptySmallSquare;
| U+025FB | ◻ |
emptyv;
| U+02205 | ∅ |
EmptyVerySmallSquare;
| U+025AB | ▫ |
emsp;
| U+02003 | |
emsp13;
| U+02004 | |
emsp14;
| U+02005 | |
ENG;
| U+0014A | Ŋ |
eng;
| U+0014B | ŋ |
ensp;
| U+02002 | |
Eogon;
| U+00118 | Ę |
eogon;
| U+00119 | ę |
Eopf;
| U+1D53C | 𝔼 |
eopf;
| U+1D556 | 𝕖 |
epar;
| U+022D5 | ⋕ |
eparsl;
| U+029E3 | ⧣ |
eplus;
| U+02A71 | ⩱ |
epsi;
| U+003B5 | ε |
Epsilon;
| U+00395 | Ε |
epsilon;
| U+003B5 | ε |
epsiv;
| U+003F5 | ϵ |
eqcirc;
| U+02256 | ≖ |
eqcolon;
| U+02255 | ≕ |
eqsim;
| U+02242 | ≂ |
eqslantgtr;
| U+02A96 | ⪖ |
eqslantless;
| U+02A95 | ⪕ |
Equal;
| U+02A75 | ⩵ |
equals;
| U+0003D | = |
EqualTilde;
| U+02242 | ≂ |
equest;
| U+0225F | ≟ |
Equilibrium;
| U+021CC | ⇌ |
equiv;
| U+02261 | ≡ |
equivDD;
| U+02A78 | ⩸ |
eqvparsl;
| U+029E5 | ⧥ |
erarr;
| U+02971 | ⥱ |
erDot;
| U+02253 | ≓ |
Escr;
| U+02130 | ℰ |
escr;
| U+0212F | ℯ |
esdot;
| U+02250 | ≐ |
Esim;
| U+02A73 | ⩳ |
esim;
| U+02242 | ≂ |
Eta;
| U+00397 | Η |
eta;
| U+003B7 | η |
ETH;
| U+000D0 | Ð |
ETH
| U+000D0 | Ð |
eth;
| U+000F0 | ð |
eth
| U+000F0 | ð |
Euml;
| U+000CB | Ë |
Euml
| U+000CB | Ë |
euml;
| U+000EB | ë |
euml
| U+000EB | ë |
euro;
| U+020AC | € |
excl;
| U+00021 | ! |
exist;
| U+02203 | ∃ |
Exists;
| U+02203 | ∃ |
expectation;
| U+02130 | ℰ |
ExponentialE;
| U+02147 | ⅇ |
exponentiale;
| U+02147 | ⅇ |
fallingdotseq;
| U+02252 | ≒ |
Fcy;
| U+00424 | Ф |
fcy;
| U+00444 | ф |
female;
| U+02640 | ♀ |
ffilig;
| U+0FB03 | ffi |
fflig;
| U+0FB00 | ff |
ffllig;
| U+0FB04 | ffl |
Ffr;
| U+1D509 | 𝔉 |
ffr;
| U+1D523 | 𝔣 |
filig;
| U+0FB01 | fi |
FilledSmallSquare;
| U+025FC | ◼ |
FilledVerySmallSquare;
| U+025AA | ▪ |
fjlig;
| U+00066 U+0006A | fj |
flat;
| U+0266D | ♭ |
fllig;
| U+0FB02 | fl |
fltns;
| U+025B1 | ▱ |
fnof;
| U+00192 | ƒ |
Fopf;
| U+1D53D | 𝔽 |
fopf;
| U+1D557 | 𝕗 |
ForAll;
| U+02200 | ∀ |
forall;
| U+02200 | ∀ |
fork;
| U+022D4 | ⋔ |
forkv;
| U+02AD9 | ⫙ |
Fouriertrf;
| U+02131 | ℱ |
fpartint;
| U+02A0D | ⨍ |
frac12;
| U+000BD | ½ |
frac12
| U+000BD | ½ |
frac13;
| U+02153 | ⅓ |
frac14;
| U+000BC | ¼ |
frac14
| U+000BC | ¼ |
frac15;
| U+02155 | ⅕ |
frac16;
| U+02159 | ⅙ |
frac18;
| U+0215B | ⅛ |
frac23;
| U+02154 | ⅔ |
frac25;
| U+02156 | ⅖ |
frac34;
| U+000BE | ¾ |
frac34
| U+000BE | ¾ |
frac35;
| U+02157 | ⅗ |
frac38;
| U+0215C | ⅜ |
frac45;
| U+02158 | ⅘ |
frac56;
| U+0215A | ⅚ |
frac58;
| U+0215D | ⅝ |
frac78;
| U+0215E | ⅞ |
frasl;
| U+02044 | ⁄ |
frown;
| U+02322 | ⌢ |
Fscr;
| U+02131 | ℱ |
fscr;
| U+1D4BB | 𝒻 |
gacute;
| U+001F5 | ǵ |
Gamma;
| U+00393 | Γ |
gamma;
| U+003B3 | γ |
Gammad;
| U+003DC | Ϝ |
gammad;
| U+003DD | ϝ |
gap;
| U+02A86 | ⪆ |
Gbreve;
| U+0011E | Ğ |
gbreve;
| U+0011F | ğ |
Gcedil;
| U+00122 | Ģ |
Gcirc;
| U+0011C | Ĝ |
gcirc;
| U+0011D | ĝ |
Gcy;
| U+00413 | Г |
gcy;
| U+00433 | г |
Gdot;
| U+00120 | Ġ |
gdot;
| U+00121 | ġ |
gE;
| U+02267 | ≧ |
ge;
| U+02265 | ≥ |
gEl;
| U+02A8C | ⪌ |
gel;
| U+022DB | ⋛ |
geq;
| U+02265 | ≥ |
geqq;
| U+02267 | ≧ |
geqslant;
| U+02A7E | ⩾ |
ges;
| U+02A7E | ⩾ |
gescc;
| U+02AA9 | ⪩ |
gesdot;
| U+02A80 | ⪀ |
gesdoto;
| U+02A82 | ⪂ |
gesdotol;
| U+02A84 | ⪄ |
gesl;
| U+022DB U+0FE00 | ⋛︀ |
gesles;
| U+02A94 | ⪔ |
Gfr;
| U+1D50A | 𝔊 |
gfr;
| U+1D524 | 𝔤 |
Gg;
| U+022D9 | ⋙ |
gg;
| U+0226B | ≫ |
ggg;
| U+022D9 | ⋙ |
gimel;
| U+02137 | ℷ |
GJcy;
| U+00403 | Ѓ |
gjcy;
| U+00453 | ѓ |
gl;
| U+02277 | ≷ |
gla;
| U+02AA5 | ⪥ |
glE;
| U+02A92 | ⪒ |
glj;
| U+02AA4 | ⪤ |
gnap;
| U+02A8A | ⪊ |
gnapprox;
| U+02A8A | ⪊ |
gnE;
| U+02269 | ≩ |
gne;
| U+02A88 | ⪈ |
gneq;
| U+02A88 | ⪈ |
gneqq;
| U+02269 | ≩ |
gnsim;
| U+022E7 | ⋧ |
Gopf;
| U+1D53E | 𝔾 |
gopf;
| U+1D558 | 𝕘 |
grave;
| U+00060 | ` |
GreaterEqual;
| U+02265 | ≥ |
GreaterEqualLess;
| U+022DB | ⋛ |
GreaterFullEqual;
| U+02267 | ≧ |
GreaterGreater;
| U+02AA2 | ⪢ |
GreaterLess;
| U+02277 | ≷ |
GreaterSlantEqual;
| U+02A7E | ⩾ |
GreaterTilde;
| U+02273 | ≳ |
Gscr;
| U+1D4A2 | 𝒢 |
gscr;
| U+0210A | ℊ |
gsim;
| U+02273 | ≳ |
gsime;
| U+02A8E | ⪎ |
gsiml;
| U+02A90 | ⪐ |
GT;
| U+0003E | > |
GT
| U+0003E | > |
Gt;
| U+0226B | ≫ |
gt;
| U+0003E | > |
gt
| U+0003E | > |
gtcc;
| U+02AA7 | ⪧ |
gtcir;
| U+02A7A | ⩺ |
gtdot;
| U+022D7 | ⋗ |
gtlPar;
| U+02995 | ⦕ |
gtquest;
| U+02A7C | ⩼ |
gtrapprox;
| U+02A86 | ⪆ |
gtrarr;
| U+02978 | ⥸ |
gtrdot;
| U+022D7 | ⋗ |
gtreqless;
| U+022DB | ⋛ |
gtreqqless;
| U+02A8C | ⪌ |
gtrless;
| U+02277 | ≷ |
gtrsim;
| U+02273 | ≳ |
gvertneqq;
| U+02269 U+0FE00 | ≩︀ |
gvnE;
| U+02269 U+0FE00 | ≩︀ |
Hacek;
| U+002C7 | ˇ |
hairsp;
| U+0200A | |
half;
| U+000BD | ½ |
hamilt;
| U+0210B | ℋ |
HARDcy;
| U+0042A | Ъ |
hardcy;
| U+0044A | ъ |
hArr;
| U+021D4 | ⇔ |
harr;
| U+02194 | ↔ |
harrcir;
| U+02948 | ⥈ |
harrw;
| U+021AD | ↭ |
Hat;
| U+0005E | ^ |
hbar;
| U+0210F | ℏ |
Hcirc;
| U+00124 | Ĥ |
hcirc;
| U+00125 | ĥ |
hearts;
| U+02665 | ♥ |
heartsuit;
| U+02665 | ♥ |
hellip;
| U+02026 | … |
hercon;
| U+022B9 | ⊹ |
Hfr;
| U+0210C | ℌ |
hfr;
| U+1D525 | 𝔥 |
HilbertSpace;
| U+0210B | ℋ |
hksearow;
| U+02925 | ⤥ |
hkswarow;
| U+02926 | ⤦ |
hoarr;
| U+021FF | ⇿ |
homtht;
| U+0223B | ∻ |
hookleftarrow;
| U+021A9 | ↩ |
hookrightarrow;
| U+021AA | ↪ |
Hopf;
| U+0210D | ℍ |
hopf;
| U+1D559 | 𝕙 |
horbar;
| U+02015 | ― |
HorizontalLine;
| U+02500 | ─ |
Hscr;
| U+0210B | ℋ |
hscr;
| U+1D4BD | 𝒽 |
hslash;
| U+0210F | ℏ |
Hstrok;
| U+00126 | Ħ |
hstrok;
| U+00127 | ħ |
HumpDownHump;
| U+0224E | ≎ |
HumpEqual;
| U+0224F | ≏ |
hybull;
| U+02043 | ⁃ |
hyphen;
| U+02010 | ‐ |
Iacute;
| U+000CD | Í |
Iacute
| U+000CD | Í |
iacute;
| U+000ED | í |
iacute
| U+000ED | í |
ic;
| U+02063 | |
Icirc;
| U+000CE | Î |
Icirc
| U+000CE | Î |
icirc;
| U+000EE | î |
icirc
| U+000EE | î |
Icy;
| U+00418 | И |
icy;
| U+00438 | и |
Idot;
| U+00130 | İ |
IEcy;
| U+00415 | Е |
iecy;
| U+00435 | е |
iexcl;
| U+000A1 | ¡ |
iexcl
| U+000A1 | ¡ |
iff;
| U+021D4 | ⇔ |
Ifr;
| U+02111 | ℑ |
ifr;
| U+1D526 | 𝔦 |
Igrave;
| U+000CC | Ì |
Igrave
| U+000CC | Ì |
igrave;
| U+000EC | ì |
igrave
| U+000EC | ì |
ii;
| U+02148 | ⅈ |
iiiint;
| U+02A0C | ⨌ |
iiint;
| U+0222D | ∭ |
iinfin;
| U+029DC | ⧜ |
iiota;
| U+02129 | ℩ |
IJlig;
| U+00132 | IJ |
ijlig;
| U+00133 | ij |
Im;
| U+02111 | ℑ |
Imacr;
| U+0012A | Ī |
imacr;
| U+0012B | ī |
image;
| U+02111 | ℑ |
ImaginaryI;
| U+02148 | ⅈ |
imagline;
| U+02110 | ℐ |
imagpart;
| U+02111 | ℑ |
imath;
| U+00131 | ı |
imof;
| U+022B7 | ⊷ |
imped;
| U+001B5 | Ƶ |
Implies;
| U+021D2 | ⇒ |
in;
| U+02208 | ∈ |
incare;
| U+02105 | ℅ |
infin;
| U+0221E | ∞ |
infintie;
| U+029DD | ⧝ |
inodot;
| U+00131 | ı |
Int;
| U+0222C | ∬ |
int;
| U+0222B | ∫ |
intcal;
| U+022BA | ⊺ |
integers;
| U+02124 | ℤ |
Integral;
| U+0222B | ∫ |
intercal;
| U+022BA | ⊺ |
Intersection;
| U+022C2 | ⋂ |
intlarhk;
| U+02A17 | ⨗ |
intprod;
| U+02A3C | ⨼ |
InvisibleComma;
| U+02063 | |
InvisibleTimes;
| U+02062 | |
IOcy;
| U+00401 | Ё |
iocy;
| U+00451 | ё |
Iogon;
| U+0012E | Į |
iogon;
| U+0012F | į |
Iopf;
| U+1D540 | 𝕀 |
iopf;
| U+1D55A | 𝕚 |
Iota;
| U+00399 | Ι |
iota;
| U+003B9 | ι |
iprod;
| U+02A3C | ⨼ |
iquest;
| U+000BF | ¿ |
iquest
| U+000BF | ¿ |
Iscr;
| U+02110 | ℐ |
iscr;
| U+1D4BE | 𝒾 |
isin;
| U+02208 | ∈ |
isindot;
| U+022F5 | ⋵ |
isinE;
| U+022F9 | ⋹ |
isins;
| U+022F4 | ⋴ |
isinsv;
| U+022F3 | ⋳ |
isinv;
| U+02208 | ∈ |
it;
| U+02062 | |
Itilde;
| U+00128 | Ĩ |
itilde;
| U+00129 | ĩ |
Iukcy;
| U+00406 | І |
iukcy;
| U+00456 | і |
Iuml;
| U+000CF | Ï |
Iuml
| U+000CF | Ï |
iuml;
| U+000EF | ï |
iuml
| U+000EF | ï |
Jcirc;
| U+00134 | Ĵ |
jcirc;
| U+00135 | ĵ |
Jcy;
| U+00419 | Й |
jcy;
| U+00439 | й |
Jfr;
| U+1D50D | 𝔍 |
jfr;
| U+1D527 | 𝔧 |
jmath;
| U+00237 | ȷ |
Jopf;
| U+1D541 | 𝕁 |
jopf;
| U+1D55B | 𝕛 |
Jscr;
| U+1D4A5 | 𝒥 |
jscr;
| U+1D4BF | 𝒿 |
Jsercy;
| U+00408 | Ј |
jsercy;
| U+00458 | ј |
Jukcy;
| U+00404 | Є |
jukcy;
| U+00454 | є |
Kappa;
| U+0039A | Κ |
kappa;
| U+003BA | κ |
kappav;
| U+003F0 | ϰ |
Kcedil;
| U+00136 | Ķ |
kcedil;
| U+00137 | ķ |
Kcy;
| U+0041A | К |
kcy;
| U+0043A | к |
Kfr;
| U+1D50E | 𝔎 |
kfr;
| U+1D528 | 𝔨 |
kgreen;
| U+00138 | ĸ |
KHcy;
| U+00425 | Х |
khcy;
| U+00445 | х |
KJcy;
| U+0040C | Ќ |
kjcy;
| U+0045C | ќ |
Kopf;
| U+1D542 | 𝕂 |
kopf;
| U+1D55C | 𝕜 |
Kscr;
| U+1D4A6 | 𝒦 |
kscr;
| U+1D4C0 | 𝓀 |
lAarr;
| U+021DA | ⇚ |
Lacute;
| U+00139 | Ĺ |
lacute;
| U+0013A | ĺ |
laemptyv;
| U+029B4 | ⦴ |
lagran;
| U+02112 | ℒ |
Lambda;
| U+0039B | Λ |
lambda;
| U+003BB | λ |
Lang;
| U+027EA | ⟪ |
lang;
| U+027E8 | ⟨ |
langd;
| U+02991 | ⦑ |
langle;
| U+027E8 | 〈 |
lap;
| U+02A85 | ⪅ |
Laplacetrf;
| U+02112 | ℒ |
laquo;
| U+000AB | « |
laquo
| U+000AB | « |
Larr;
| U+0219E | ↞ |
lArr;
| U+021D0 | ⇐ |
larr;
| U+02190 | ← |
larrb;
| U+021E4 | ⇤ |
larrbfs;
| U+0291F | ⤟ |
larrfs;
| U+0291D | ⤝ |
larrhk;
| U+021A9 | ↩ |
larrlp;
| U+021AB | ↫ |
larrpl;
| U+02939 | ⤹ |
larrsim;
| U+02973 | ⥳ |
larrtl;
| U+021A2 | ↢ |
lat;
| U+02AAB | ⪫ |
lAtail;
| U+0291B | ⤛ |
latail;
| U+02919 | ⤙ |
late;
| U+02AAD | ⪭ |
lates;
| U+02AAD U+0FE00 | ⪭︀ |
lBarr;
| U+0290E | ⤎ |
lbarr;
| U+0290C | ⤌ |
lbbrk;
| U+02772 | ❲ |
lbrace;
| U+0007B | { |
lbrack;
| U+0005B | [ |
lbrke;
| U+0298B | ⦋ |
lbrksld;
| U+0298F | ⦏ |
lbrkslu;
| U+0298D | ⦍ |
Lcaron;
| U+0013D | Ľ |
lcaron;
| U+0013E | ľ |
Lcedil;
| U+0013B | Ļ |
lcedil;
| U+0013C | ļ |
lceil;
| U+02308 | ⌈ |
lcub;
| U+0007B | { |
Lcy;
| U+0041B | Л |
lcy;
| U+0043B | л |
ldca;
| U+02936 | ⤶ |
ldquo;
| U+0201C | “ |
ldquor;
| U+0201E | „ |
ldrdhar;
| U+02967 | ⥧ |
ldrushar;
| U+0294B | ⥋ |
ldsh;
| U+021B2 | ↲ |
lE;
| U+02266 | ≦ |
le;
| U+02264 | ≤ |
LeftAngleBracket;
| U+027E8 | 〈 |
LeftArrow;
| U+02190 | ← |
Leftarrow;
| U+021D0 | ⇐ |
leftarrow;
| U+02190 | ← |
LeftArrowBar;
| U+021E4 | ⇤ |
LeftArrowRightArrow;
| U+021C6 | ⇆ |
leftarrowtail;
| U+021A2 | ↢ |
LeftCeiling;
| U+02308 | ⌈ |
LeftDoubleBracket;
| U+027E6 | ⟦ |
LeftDownTeeVector;
| U+02961 | ⥡ |
LeftDownVector;
| U+021C3 | ⇃ |
LeftDownVectorBar;
| U+02959 | ⥙ |
LeftFloor;
| U+0230A | ⌊ |
leftharpoondown;
| U+021BD | ↽ |
leftharpoonup;
| U+021BC | ↼ |
leftleftarrows;
| U+021C7 | ⇇ |
LeftRightArrow;
| U+02194 | ↔ |
Leftrightarrow;
| U+021D4 | ⇔ |
leftrightarrow;
| U+02194 | ↔ |
leftrightarrows;
| U+021C6 | ⇆ |
leftrightharpoons;
| U+021CB | ⇋ |
leftrightsquigarrow;
| U+021AD | ↭ |
LeftRightVector;
| U+0294E | ⥎ |
LeftTee;
| U+022A3 | ⊣ |
LeftTeeArrow;
| U+021A4 | ↤ |
LeftTeeVector;
| U+0295A | ⥚ |
leftthreetimes;
| U+022CB | ⋋ |
LeftTriangle;
| U+022B2 | ⊲ |
LeftTriangleBar;
| U+029CF | ⧏ |
LeftTriangleEqual;
| U+022B4 | ⊴ |
LeftUpDownVector;
| U+02951 | ⥑ |
LeftUpTeeVector;
| U+02960 | ⥠ |
LeftUpVector;
| U+021BF | ↿ |
LeftUpVectorBar;
| U+02958 | ⥘ |
LeftVector;
| U+021BC | ↼ |
LeftVectorBar;
| U+02952 | ⥒ |
lEg;
| U+02A8B | ⪋ |
leg;
| U+022DA | ⋚ |
leq;
| U+02264 | ≤ |
leqq;
| U+02266 | ≦ |
leqslant;
| U+02A7D | ⩽ |
les;
| U+02A7D | ⩽ |
lescc;
| U+02AA8 | ⪨ |
lesdot;
| U+02A7F | ⩿ |
lesdoto;
| U+02A81 | ⪁ |
lesdotor;
| U+02A83 | ⪃ |
lesg;
| U+022DA U+0FE00 | ⋚︀ |
lesges;
| U+02A93 | ⪓ |
lessapprox;
| U+02A85 | ⪅ |
lessdot;
| U+022D6 | ⋖ |
lesseqgtr;
| U+022DA | ⋚ |
lesseqqgtr;
| U+02A8B | ⪋ |
LessEqualGreater;
| U+022DA | ⋚ |
LessFullEqual;
| U+02266 | ≦ |
LessGreater;
| U+02276 | ≶ |
lessgtr;
| U+02276 | ≶ |
LessLess;
| U+02AA1 | ⪡ |
lesssim;
| U+02272 | ≲ |
LessSlantEqual;
| U+02A7D | ⩽ |
LessTilde;
| U+02272 | ≲ |
lfisht;
| U+0297C | ⥼ |
lfloor;
| U+0230A | ⌊ |
Lfr;
| U+1D50F | 𝔏 |
lfr;
| U+1D529 | 𝔩 |
lg;
| U+02276 | ≶ |
lgE;
| U+02A91 | ⪑ |
lHar;
| U+02962 | ⥢ |
lhard;
| U+021BD | ↽ |
lharu;
| U+021BC | ↼ |
lharul;
| U+0296A | ⥪ |
lhblk;
| U+02584 | ▄ |
LJcy;
| U+00409 | Љ |
ljcy;
| U+00459 | љ |
Ll;
| U+022D8 | ⋘ |
ll;
| U+0226A | ≪ |
llarr;
| U+021C7 | ⇇ |
llcorner;
| U+0231E | ⌞ |
Lleftarrow;
| U+021DA | ⇚ |
llhard;
| U+0296B | ⥫ |
lltri;
| U+025FA | ◺ |
Lmidot;
| U+0013F | Ŀ |
lmidot;
| U+00140 | ŀ |
lmoust;
| U+023B0 | ⎰ |
lmoustache;
| U+023B0 | ⎰ |
lnap;
| U+02A89 | ⪉ |
lnapprox;
| U+02A89 | ⪉ |
lnE;
| U+02268 | ≨ |
lne;
| U+02A87 | ⪇ |
lneq;
| U+02A87 | ⪇ |
lneqq;
| U+02268 | ≨ |
lnsim;
| U+022E6 | ⋦ |
loang;
| U+027EC | ⟬ |
loarr;
| U+021FD | ⇽ |
lobrk;
| U+027E6 | ⟦ |
LongLeftArrow;
| U+027F5 | ⟵ |
Longleftarrow;
| U+027F8 | ⟸ |
longleftarrow;
| U+027F5 | ⟵ |
LongLeftRightArrow;
| U+027F7 | ⟷ |
Longleftrightarrow;
| U+027FA | ⟺ |
longleftrightarrow;
| U+027F7 | ⟷ |
longmapsto;
| U+027FC | ⟼ |
LongRightArrow;
| U+027F6 | ⟶ |
Longrightarrow;
| U+027F9 | ⟹ |
longrightarrow;
| U+027F6 | ⟶ |
looparrowleft;
| U+021AB | ↫ |
looparrowright;
| U+021AC | ↬ |
lopar;
| U+02985 | ⦅ |
Lopf;
| U+1D543 | 𝕃 |
lopf;
| U+1D55D | 𝕝 |
loplus;
| U+02A2D | ⨭ |
lotimes;
| U+02A34 | ⨴ |
lowast;
| U+02217 | ∗ |
lowbar;
| U+0005F | _ |
LowerLeftArrow;
| U+02199 | ↙ |
LowerRightArrow;
| U+02198 | ↘ |
loz;
| U+025CA | ◊ |
lozenge;
| U+025CA | ◊ |
lozf;
| U+029EB | ⧫ |
lpar;
| U+00028 | ( |
lparlt;
| U+02993 | ⦓ |
lrarr;
| U+021C6 | ⇆ |
lrcorner;
| U+0231F | ⌟ |
lrhar;
| U+021CB | ⇋ |
lrhard;
| U+0296D | ⥭ |
lrm;
| U+0200E | |
lrtri;
| U+022BF | ⊿ |
lsaquo;
| U+02039 | ‹ |
Lscr;
| U+02112 | ℒ |
lscr;
| U+1D4C1 | 𝓁 |
Lsh;
| U+021B0 | ↰ |
lsh;
| U+021B0 | ↰ |
lsim;
| U+02272 | ≲ |
lsime;
| U+02A8D | ⪍ |
lsimg;
| U+02A8F | ⪏ |
lsqb;
| U+0005B | [ |
lsquo;
| U+02018 | ‘ |
lsquor;
| U+0201A | ‚ |
Lstrok;
| U+00141 | Ł |
lstrok;
| U+00142 | ł |
LT;
| U+0003C | < |
LT
| U+0003C | < |
Lt;
| U+0226A | ≪ |
lt;
| U+0003C | < |
lt
| U+0003C | < |
ltcc;
| U+02AA6 | ⪦ |
ltcir;
| U+02A79 | ⩹ |
ltdot;
| U+022D6 | ⋖ |
lthree;
| U+022CB | ⋋ |
ltimes;
| U+022C9 | ⋉ |
ltlarr;
| U+02976 | ⥶ |
ltquest;
| U+02A7B | ⩻ |
ltri;
| U+025C3 | ◃ |
ltrie;
| U+022B4 | ⊴ |
ltrif;
| U+025C2 | ◂ |
ltrPar;
| U+02996 | ⦖ |
lurdshar;
| U+0294A | ⥊ |
luruhar;
| U+02966 | ⥦ |
lvertneqq;
| U+02268 U+0FE00 | ≨︀ |
lvnE;
| U+02268 U+0FE00 | ≨︀ |
macr;
| U+000AF | ¯ |
macr
| U+000AF | ¯ |
male;
| U+02642 | ♂ |
malt;
| U+02720 | ✠ |
maltese;
| U+02720 | ✠ |
Map;
| U+02905 | ⤅ |
map;
| U+021A6 | ↦ |
mapsto;
| U+021A6 | ↦ |
mapstodown;
| U+021A7 | ↧ |
mapstoleft;
| U+021A4 | ↤ |
mapstoup;
| U+021A5 | ↥ |
marker;
| U+025AE | ▮ |
mcomma;
| U+02A29 | ⨩ |
Mcy;
| U+0041C | М |
mcy;
| U+0043C | м |
mdash;
| U+02014 | — |
mDDot;
| U+0223A | ∺ |
measuredangle;
| U+02221 | ∡ |
MediumSpace;
| U+0205F | |
Mellintrf;
| U+02133 | ℳ |
Mfr;
| U+1D510 | 𝔐 |
mfr;
| U+1D52A | 𝔪 |
mho;
| U+02127 | ℧ |
micro;
| U+000B5 | µ |
micro
| U+000B5 | µ |
mid;
| U+02223 | ∣ |
midast;
| U+0002A | * |
midcir;
| U+02AF0 | ⫰ |
middot;
| U+000B7 | · |
middot
| U+000B7 | · |
minus;
| U+02212 | − |
minusb;
| U+0229F | ⊟ |
minusd;
| U+02238 | ∸ |
minusdu;
| U+02A2A | ⨪ |
MinusPlus;
| U+02213 | ∓ |
mlcp;
| U+02ADB | ⫛ |
mldr;
| U+02026 | … |
mnplus;
| U+02213 | ∓ |
models;
| U+022A7 | ⊧ |
Mopf;
| U+1D544 | 𝕄 |
mopf;
| U+1D55E | 𝕞 |
mp;
| U+02213 | ∓ |
Mscr;
| U+02133 | ℳ |
mscr;
| U+1D4C2 | 𝓂 |
mstpos;
| U+0223E | ∾ |
Mu;
| U+0039C | Μ |
mu;
| U+003BC | μ |
multimap;
| U+022B8 | ⊸ |
mumap;
| U+022B8 | ⊸ |
nabla;
| U+02207 | ∇ |
Nacute;
| U+00143 | Ń |
nacute;
| U+00144 | ń |
nang;
| U+02220 U+020D2 | ∠⃒ |
nap;
| U+02249 | ≉ |
napE;
| U+02A70 U+00338 | ⩰̸ |
napid;
| U+0224B U+00338 | ≋̸ |
napos;
| U+00149 | ʼn |
napprox;
| U+02249 | ≉ |
natur;
| U+0266E | ♮ |
natural;
| U+0266E | ♮ |
naturals;
| U+02115 | ℕ |
nbsp;
| U+000A0 | |
nbsp
| U+000A0 | |
nbump;
| U+0224E U+00338 | ≎̸ |
nbumpe;
| U+0224F U+00338 | ≏̸ |
ncap;
| U+02A43 | ⩃ |
Ncaron;
| U+00147 | Ň |
ncaron;
| U+00148 | ň |
Ncedil;
| U+00145 | Ņ |
ncedil;
| U+00146 | ņ |
ncong;
| U+02247 | ≇ |
ncongdot;
| U+02A6D U+00338 | ⩭̸ |
ncup;
| U+02A42 | ⩂ |
Ncy;
| U+0041D | Н |
ncy;
| U+0043D | н |
ndash;
| U+02013 | – |
ne;
| U+02260 | ≠ |
nearhk;
| U+02924 | ⤤ |
neArr;
| U+021D7 | ⇗ |
nearr;
| U+02197 | ↗ |
nearrow;
| U+02197 | ↗ |
nedot;
| U+02250 U+00338 | ≐̸ |
NegativeMediumSpace;
| U+0200B | |
NegativeThickSpace;
| U+0200B | |
NegativeThinSpace;
| U+0200B | |
NegativeVeryThinSpace;
| U+0200B | |
nequiv;
| U+02262 | ≢ |
nesear;
| U+02928 | ⤨ |
nesim;
| U+02242 U+00338 | ≂̸ |
NestedGreaterGreater;
| U+0226B | ≫ |
NestedLessLess;
| U+0226A | ≪ |
NewLine;
| U+0000A | ␊ |
nexist;
| U+02204 | ∄ |
nexists;
| U+02204 | ∄ |
Nfr;
| U+1D511 | 𝔑 |
nfr;
| U+1D52B | 𝔫 |
ngE;
| U+02267 U+00338 | ≧̸ |
nge;
| U+02271 | ≱ |
ngeq;
| U+02271 | ≱ |
ngeqq;
| U+02267 U+00338 | ≧̸ |
ngeqslant;
| U+02A7E U+00338 | ⩾̸ |
nges;
| U+02A7E U+00338 | ⩾̸ |
nGg;
| U+022D9 U+00338 | ⋙̸ |
ngsim;
| U+02275 | ≵ |
nGt;
| U+0226B U+020D2 | ≫⃒ |
ngt;
| U+0226F | ≯ |
ngtr;
| U+0226F | ≯ |
nGtv;
| U+0226B U+00338 | ≫̸ |
nhArr;
| U+021CE | ⇎ |
nharr;
| U+021AE | ↮ |
nhpar;
| U+02AF2 | ⫲ |
ni;
| U+0220B | ∋ |
nis;
| U+022FC | ⋼ |
nisd;
| U+022FA | ⋺ |
niv;
| U+0220B | ∋ |
NJcy;
| U+0040A | Њ |
njcy;
| U+0045A | њ |
nlArr;
| U+021CD | ⇍ |
nlarr;
| U+0219A | ↚ |
nldr;
| U+02025 | ‥ |
nlE;
| U+02266 U+00338 | ≦̸ |
nle;
| U+02270 | ≰ |
nLeftarrow;
| U+021CD | ⇍ |
nleftarrow;
| U+0219A | ↚ |
nLeftrightarrow;
| U+021CE | ⇎ |
nleftrightarrow;
| U+021AE | ↮ |
nleq;
| U+02270 | ≰ |
nleqq;
| U+02266 U+00338 | ≦̸ |
nleqslant;
| U+02A7D U+00338 | ⩽̸ |
nles;
| U+02A7D U+00338 | ⩽̸ |
nless;
| U+0226E | ≮ |
nLl;
| U+022D8 U+00338 | ⋘̸ |
nlsim;
| U+02274 | ≴ |
nLt;
| U+0226A U+020D2 | ≪⃒ |
nlt;
| U+0226E | ≮ |
nltri;
| U+022EA | ⋪ |
nltrie;
| U+022EC | ⋬ |
nLtv;
| U+0226A U+00338 | ≪̸ |
nmid;
| U+02224 | ∤ |
NoBreak;
| U+02060 | |
NonBreakingSpace;
| U+000A0 | |
Nopf;
| U+02115 | ℕ |
nopf;
| U+1D55F | 𝕟 |
Not;
| U+02AEC | ⫬ |
not;
| U+000AC | ¬ |
not
| U+000AC | ¬ |
NotCongruent;
| U+02262 | ≢ |
NotCupCap;
| U+0226D | ≭ |
NotDoubleVerticalBar;
| U+02226 | ∦ |
NotElement;
| U+02209 | ∉ |
NotEqual;
| U+02260 | ≠ |
NotEqualTilde;
| U+02242 U+00338 | ≂̸ |
NotExists;
| U+02204 | ∄ |
NotGreater;
| U+0226F | ≯ |
NotGreaterEqual;
| U+02271 | ≱ |
NotGreaterFullEqual;
| U+02267 U+00338 | ≧̸ |
NotGreaterGreater;
| U+0226B U+00338 | ≫̸ |
NotGreaterLess;
| U+02279 | ≹ |
NotGreaterSlantEqual;
| U+02A7E U+00338 | ⩾̸ |
NotGreaterTilde;
| U+02275 | ≵ |
NotHumpDownHump;
| U+0224E U+00338 | ≎̸ |
NotHumpEqual;
| U+0224F U+00338 | ≏̸ |
notin;
| U+02209 | ∉ |
notindot;
| U+022F5 U+00338 | ⋵̸ |
notinE;
| U+022F9 U+00338 | ⋹̸ |
notinva;
| U+02209 | ∉ |
notinvb;
| U+022F7 | ⋷ |
notinvc;
| U+022F6 | ⋶ |
NotLeftTriangle;
| U+022EA | ⋪ |
NotLeftTriangleBar;
| U+029CF U+00338 | ⧏̸ |
NotLeftTriangleEqual;
| U+022EC | ⋬ |
NotLess;
| U+0226E | ≮ |
NotLessEqual;
| U+02270 | ≰ |
NotLessGreater;
| U+02278 | ≸ |
NotLessLess;
| U+0226A U+00338 | ≪̸ |
NotLessSlantEqual;
| U+02A7D U+00338 | ⩽̸ |
NotLessTilde;
| U+02274 | ≴ |
NotNestedGreaterGreater;
| U+02AA2 U+00338 | ⪢̸ |
NotNestedLessLess;
| U+02AA1 U+00338 | ⪡̸ |
notni;
| U+0220C | ∌ |
notniva;
| U+0220C | ∌ |
notnivb;
| U+022FE | ⋾ |
notnivc;
| U+022FD | ⋽ |
NotPrecedes;
| U+02280 | ⊀ |
NotPrecedesEqual;
| U+02AAF U+00338 | ⪯̸ |
NotPrecedesSlantEqual;
| U+022E0 | ⋠ |
NotReverseElement;
| U+0220C | ∌ |
NotRightTriangle;
| U+022EB | ⋫ |
NotRightTriangleBar;
| U+029D0 U+00338 | ⧐̸ |
NotRightTriangleEqual;
| U+022ED | ⋭ |
NotSquareSubset;
| U+0228F U+00338 | ⊏̸ |
NotSquareSubsetEqual;
| U+022E2 | ⋢ |
NotSquareSuperset;
| U+02290 U+00338 | ⊐̸ |
NotSquareSupersetEqual;
| U+022E3 | ⋣ |
NotSubset;
| U+02282 U+020D2 | ⊂⃒ |
NotSubsetEqual;
| U+02288 | ⊈ |
NotSucceeds;
| U+02281 | ⊁ |
NotSucceedsEqual;
| U+02AB0 U+00338 | ⪰̸ |
NotSucceedsSlantEqual;
| U+022E1 | ⋡ |
NotSucceedsTilde;
| U+0227F U+00338 | ≿̸ |
NotSuperset;
| U+02283 U+020D2 | ⊃⃒ |
NotSupersetEqual;
| U+02289 | ⊉ |
NotTilde;
| U+02241 | ≁ |
NotTildeEqual;
| U+02244 | ≄ |
NotTildeFullEqual;
| U+02247 | ≇ |
NotTildeTilde;
| U+02249 | ≉ |
NotVerticalBar;
| U+02224 | ∤ |
npar;
| U+02226 | ∦ |
nparallel;
| U+02226 | ∦ |
nparsl;
| U+02AFD U+020E5 | ⫽⃥ |
npart;
| U+02202 U+00338 | ∂̸ |
npolint;
| U+02A14 | ⨔ |
npr;
| U+02280 | ⊀ |
nprcue;
| U+022E0 | ⋠ |
npre;
| U+02AAF U+00338 | ⪯̸ |
nprec;
| U+02280 | ⊀ |
npreceq;
| U+02AAF U+00338 | ⪯̸ |
nrArr;
| U+021CF | ⇏ |
nrarr;
| U+0219B | ↛ |
nrarrc;
| U+02933 U+00338 | ⤳̸ |
nrarrw;
| U+0219D U+00338 | ↝̸ |
nRightarrow;
| U+021CF | ⇏ |
nrightarrow;
| U+0219B | ↛ |
nrtri;
| U+022EB | ⋫ |
nrtrie;
| U+022ED | ⋭ |
nsc;
| U+02281 | ⊁ |
nsccue;
| U+022E1 | ⋡ |
nsce;
| U+02AB0 U+00338 | ⪰̸ |
Nscr;
| U+1D4A9 | 𝒩 |
nscr;
| U+1D4C3 | 𝓃 |
nshortmid;
| U+02224 | ∤ |
nshortparallel;
| U+02226 | ∦ |
nsim;
| U+02241 | ≁ |
nsime;
| U+02244 | ≄ |
nsimeq;
| U+02244 | ≄ |
nsmid;
| U+02224 | ∤ |
nspar;
| U+02226 | ∦ |
nsqsube;
| U+022E2 | ⋢ |
nsqsupe;
| U+022E3 | ⋣ |
nsub;
| U+02284 | ⊄ |
nsubE;
| U+02AC5 U+00338 | ⫅̸ |
nsube;
| U+02288 | ⊈ |
nsubset;
| U+02282 U+020D2 | ⊂⃒ |
nsubseteq;
| U+02288 | ⊈ |
nsubseteqq;
| U+02AC5 U+00338 | ⫅̸ |
nsucc;
| U+02281 | ⊁ |
nsucceq;
| U+02AB0 U+00338 | ⪰̸ |
nsup;
| U+02285 | ⊅ |
nsupE;
| U+02AC6 U+00338 | ⫆̸ |
nsupe;
| U+02289 | ⊉ |
nsupset;
| U+02283 U+020D2 | ⊃⃒ |
nsupseteq;
| U+02289 | ⊉ |
nsupseteqq;
| U+02AC6 U+00338 | ⫆̸ |
ntgl;
| U+02279 | ≹ |
Ntilde;
| U+000D1 | Ñ |
Ntilde
| U+000D1 | Ñ |
ntilde;
| U+000F1 | ñ |
ntilde
| U+000F1 | ñ |
ntlg;
| U+02278 | ≸ |
ntriangleleft;
| U+022EA | ⋪ |
ntrianglelefteq;
| U+022EC | ⋬ |
ntriangleright;
| U+022EB | ⋫ |
ntrianglerighteq;
| U+022ED | ⋭ |
Nu;
| U+0039D | Ν |
nu;
| U+003BD | ν |
num;
| U+00023 | # |
numero;
| U+02116 | № |
numsp;
| U+02007 | |
nvap;
| U+0224D U+020D2 | ≍⃒ |
nVDash;
| U+022AF | ⊯ |
nVdash;
| U+022AE | ⊮ |
nvDash;
| U+022AD | ⊭ |
nvdash;
| U+022AC | ⊬ |
nvge;
| U+02265 U+020D2 | ≥⃒ |
nvgt;
| U+0003E U+020D2 | >⃒ |
nvHarr;
| U+02904 | ⤄ |
nvinfin;
| U+029DE | ⧞ |
nvlArr;
| U+02902 | ⤂ |
nvle;
| U+02264 U+020D2 | ≤⃒ |
nvlt;
| U+0003C U+020D2 | <⃒ |
nvltrie;
| U+022B4 U+020D2 | ⊴⃒ |
nvrArr;
| U+02903 | ⤃ |
nvrtrie;
| U+022B5 U+020D2 | ⊵⃒ |
nvsim;
| U+0223C U+020D2 | ∼⃒ |
nwarhk;
| U+02923 | ⤣ |
nwArr;
| U+021D6 | ⇖ |
nwarr;
| U+02196 | ↖ |
nwarrow;
| U+02196 | ↖ |
nwnear;
| U+02927 | ⤧ |
Oacute;
| U+000D3 | Ó |
Oacute
| U+000D3 | Ó |
oacute;
| U+000F3 | ó |
oacute
| U+000F3 | ó |
oast;
| U+0229B | ⊛ |
ocir;
| U+0229A | ⊚ |
Ocirc;
| U+000D4 | Ô |
Ocirc
| U+000D4 | Ô |
ocirc;
| U+000F4 | ô |
ocirc
| U+000F4 | ô |
Ocy;
| U+0041E | О |
ocy;
| U+0043E | о |
odash;
| U+0229D | ⊝ |
Odblac;
| U+00150 | Ő |
odblac;
| U+00151 | ő |
odiv;
| U+02A38 | ⨸ |
odot;
| U+02299 | ⊙ |
odsold;
| U+029BC | ⦼ |
OElig;
| U+00152 | Œ |
oelig;
| U+00153 | œ |
ofcir;
| U+029BF | ⦿ |
Ofr;
| U+1D512 | 𝔒 |
ofr;
| U+1D52C | 𝔬 |
ogon;
| U+002DB | ˛ |
Ograve;
| U+000D2 | Ò |
Ograve
| U+000D2 | Ò |
ograve;
| U+000F2 | ò |
ograve
| U+000F2 | ò |
ogt;
| U+029C1 | ⧁ |
ohbar;
| U+029B5 | ⦵ |
ohm;
| U+003A9 | Ω |
oint;
| U+0222E | ∮ |
olarr;
| U+021BA | ↺ |
olcir;
| U+029BE | ⦾ |
olcross;
| U+029BB | ⦻ |
oline;
| U+0203E | ‾ |
olt;
| U+029C0 | ⧀ |
Omacr;
| U+0014C | Ō |
omacr;
| U+0014D | ō |
Omega;
| U+003A9 | Ω |
omega;
| U+003C9 | ω |
Omicron;
| U+0039F | Ο |
omicron;
| U+003BF | ο |
omid;
| U+029B6 | ⦶ |
ominus;
| U+02296 | ⊖ |
Oopf;
| U+1D546 | 𝕆 |
oopf;
| U+1D560 | 𝕠 |
opar;
| U+029B7 | ⦷ |
OpenCurlyDoubleQuote;
| U+0201C | “ |
OpenCurlyQuote;
| U+02018 | ‘ |
operp;
| U+029B9 | ⦹ |
oplus;
| U+02295 | ⊕ |
Or;
| U+02A54 | ⩔ |
or;
| U+02228 | ∨ |
orarr;
| U+021BB | ↻ |
ord;
| U+02A5D | ⩝ |
order;
| U+02134 | ℴ |
orderof;
| U+02134 | ℴ |
ordf;
| U+000AA | ª |
ordf
| U+000AA | ª |
ordm;
| U+000BA | º |
ordm
| U+000BA | º |
origof;
| U+022B6 | ⊶ |
oror;
| U+02A56 | ⩖ |
orslope;
| U+02A57 | ⩗ |
orv;
| U+02A5B | ⩛ |
oS;
| U+024C8 | Ⓢ |
Oscr;
| U+1D4AA | 𝒪 |
oscr;
| U+02134 | ℴ |
Oslash;
| U+000D8 | Ø |
Oslash
| U+000D8 | Ø |
oslash;
| U+000F8 | ø |
oslash
| U+000F8 | ø |
osol;
| U+02298 | ⊘ |
Otilde;
| U+000D5 | Õ |
Otilde
| U+000D5 | Õ |
otilde;
| U+000F5 | õ |
otilde
| U+000F5 | õ |
Otimes;
| U+02A37 | ⨷ |
otimes;
| U+02297 | ⊗ |
otimesas;
| U+02A36 | ⨶ |
Ouml;
| U+000D6 | Ö |
Ouml
| U+000D6 | Ö |
ouml;
| U+000F6 | ö |
ouml
| U+000F6 | ö |
ovbar;
| U+0233D | ⌽ |
OverBar;
| U+0203E | ‾ |
OverBrace;
| U+023DE | ⏞ |
OverBracket;
| U+023B4 | ⎴ |
OverParenthesis;
| U+023DC | ⏜ |
par;
| U+02225 | ∥ |
para;
| U+000B6 | ¶ |
para
| U+000B6 | ¶ |
parallel;
| U+02225 | ∥ |
parsim;
| U+02AF3 | ⫳ |
parsl;
| U+02AFD | ⫽ |
part;
| U+02202 | ∂ |
PartialD;
| U+02202 | ∂ |
Pcy;
| U+0041F | П |
pcy;
| U+0043F | п |
percnt;
| U+00025 | % |
period;
| U+0002E | . |
permil;
| U+02030 | ‰ |
perp;
| U+022A5 | ⊥ |
pertenk;
| U+02031 | ‱ |
Pfr;
| U+1D513 | 𝔓 |
pfr;
| U+1D52D | 𝔭 |
Phi;
| U+003A6 | Φ |
phi;
| U+003C6 | φ |
phiv;
| U+003D5 | ϕ |
phmmat;
| U+02133 | ℳ |
phone;
| U+0260E | ☎ |
Pi;
| U+003A0 | Π |
pi;
| U+003C0 | π |
pitchfork;
| U+022D4 | ⋔ |
piv;
| U+003D6 | ϖ |
planck;
| U+0210F | ℏ |
planckh;
| U+0210E | ℎ |
plankv;
| U+0210F | ℏ |
plus;
| U+0002B | + |
plusacir;
| U+02A23 | ⨣ |
plusb;
| U+0229E | ⊞ |
pluscir;
| U+02A22 | ⨢ |
plusdo;
| U+02214 | ∔ |
plusdu;
| U+02A25 | ⨥ |
pluse;
| U+02A72 | ⩲ |
PlusMinus;
| U+000B1 | ± |
plusmn;
| U+000B1 | ± |
plusmn
| U+000B1 | ± |
plussim;
| U+02A26 | ⨦ |
plustwo;
| U+02A27 | ⨧ |
pm;
| U+000B1 | ± |
Poincareplane;
| U+0210C | ℌ |
pointint;
| U+02A15 | ⨕ |
Popf;
| U+02119 | ℙ |
popf;
| U+1D561 | 𝕡 |
pound;
| U+000A3 | £ |
pound
| U+000A3 | £ |
Pr;
| U+02ABB | ⪻ |
pr;
| U+0227A | ≺ |
prap;
| U+02AB7 | ⪷ |
prcue;
| U+0227C | ≼ |
prE;
| U+02AB3 | ⪳ |
pre;
| U+02AAF | ⪯ |
prec;
| U+0227A | ≺ |
precapprox;
| U+02AB7 | ⪷ |
preccurlyeq;
| U+0227C | ≼ |
Precedes;
| U+0227A | ≺ |
PrecedesEqual;
| U+02AAF | ⪯ |
PrecedesSlantEqual;
| U+0227C | ≼ |
PrecedesTilde;
| U+0227E | ≾ |
preceq;
| U+02AAF | ⪯ |
precnapprox;
| U+02AB9 | ⪹ |
precneqq;
| U+02AB5 | ⪵ |
precnsim;
| U+022E8 | ⋨ |
precsim;
| U+0227E | ≾ |
Prime;
| U+02033 | ″ |
prime;
| U+02032 | ′ |
primes;
| U+02119 | ℙ |
prnap;
| U+02AB9 | ⪹ |
prnE;
| U+02AB5 | ⪵ |
prnsim;
| U+022E8 | ⋨ |
prod;
| U+0220F | ∏ |
Product;
| U+0220F | ∏ |
profalar;
| U+0232E | ⌮ |
profline;
| U+02312 | ⌒ |
profsurf;
| U+02313 | ⌓ |
prop;
| U+0221D | ∝ |
Proportion;
| U+02237 | ∷ |
Proportional;
| U+0221D | ∝ |
propto;
| U+0221D | ∝ |
prsim;
| U+0227E | ≾ |
prurel;
| U+022B0 | ⊰ |
Pscr;
| U+1D4AB | 𝒫 |
pscr;
| U+1D4C5 | 𝓅 |
Psi;
| U+003A8 | Ψ |
psi;
| U+003C8 | ψ |
puncsp;
| U+02008 | |
Qfr;
| U+1D514 | 𝔔 |
qfr;
| U+1D52E | 𝔮 |
qint;
| U+02A0C | ⨌ |
Qopf;
| U+0211A | ℚ |
qopf;
| U+1D562 | 𝕢 |
qprime;
| U+02057 | ⁗ |
Qscr;
| U+1D4AC | 𝒬 |
qscr;
| U+1D4C6 | 𝓆 |
quaternions;
| U+0210D | ℍ |
quatint;
| U+02A16 | ⨖ |
quest;
| U+0003F | ? |
questeq;
| U+0225F | ≟ |
QUOT;
| U+00022 | " |
QUOT
| U+00022 | " |
quot;
| U+00022 | " |
quot
| U+00022 | " |
rAarr;
| U+021DB | ⇛ |
race;
| U+0223D U+00331 | ∽̱ |
Racute;
| U+00154 | Ŕ |
racute;
| U+00155 | ŕ |
radic;
| U+0221A | √ |
raemptyv;
| U+029B3 | ⦳ |
Rang;
| U+027EB | ⟫ |
rang;
| U+027E9 | ⟩ |
rangd;
| U+02992 | ⦒ |
range;
| U+029A5 | ⦥ |
rangle;
| U+027E9 | 〉 |
raquo;
| U+000BB | » |
raquo
| U+000BB | » |
Rarr;
| U+021A0 | ↠ |
rArr;
| U+021D2 | ⇒ |
rarr;
| U+02192 | → |
rarrap;
| U+02975 | ⥵ |
rarrb;
| U+021E5 | ⇥ |
rarrbfs;
| U+02920 | ⤠ |
rarrc;
| U+02933 | ⤳ |
rarrfs;
| U+0291E | ⤞ |
rarrhk;
| U+021AA | ↪ |
rarrlp;
| U+021AC | ↬ |
rarrpl;
| U+02945 | ⥅ |
rarrsim;
| U+02974 | ⥴ |
Rarrtl;
| U+02916 | ⤖ |
rarrtl;
| U+021A3 | ↣ |
rarrw;
| U+0219D | ↝ |
rAtail;
| U+0291C | ⤜ |
ratail;
| U+0291A | ⤚ |
ratio;
| U+02236 | ∶ |
rationals;
| U+0211A | ℚ |
RBarr;
| U+02910 | ⤐ |
rBarr;
| U+0290F | ⤏ |
rbarr;
| U+0290D | ⤍ |
rbbrk;
| U+02773 | ❳ |
rbrace;
| U+0007D | } |
rbrack;
| U+0005D | ] |
rbrke;
| U+0298C | ⦌ |
rbrksld;
| U+0298E | ⦎ |
rbrkslu;
| U+02990 | ⦐ |
Rcaron;
| U+00158 | Ř |
rcaron;
| U+00159 | ř |
Rcedil;
| U+00156 | Ŗ |
rcedil;
| U+00157 | ŗ |
rceil;
| U+02309 | ⌉ |
rcub;
| U+0007D | } |
Rcy;
| U+00420 | Р |
rcy;
| U+00440 | р |
rdca;
| U+02937 | ⤷ |
rdldhar;
| U+02969 | ⥩ |
rdquo;
| U+0201D | ” |
rdquor;
| U+0201D | ” |
rdsh;
| U+021B3 | ↳ |
Re;
| U+0211C | ℜ |
real;
| U+0211C | ℜ |
realine;
| U+0211B | ℛ |
realpart;
| U+0211C | ℜ |
reals;
| U+0211D | ℝ |
rect;
| U+025AD | ▭ |
REG;
| U+000AE | ® |
REG
| U+000AE | ® |
reg;
| U+000AE | ® |
reg
| U+000AE | ® |
ReverseElement;
| U+0220B | ∋ |
ReverseEquilibrium;
| U+021CB | ⇋ |
ReverseUpEquilibrium;
| U+0296F | ⥯ |
rfisht;
| U+0297D | ⥽ |
rfloor;
| U+0230B | ⌋ |
Rfr;
| U+0211C | ℜ |
rfr;
| U+1D52F | 𝔯 |
rHar;
| U+02964 | ⥤ |
rhard;
| U+021C1 | ⇁ |
rharu;
| U+021C0 | ⇀ |
rharul;
| U+0296C | ⥬ |
Rho;
| U+003A1 | Ρ |
rho;
| U+003C1 | ρ |
rhov;
| U+003F1 | ϱ |
RightAngleBracket;
| U+027E9 | 〉 |
RightArrow;
| U+02192 | → |
Rightarrow;
| U+021D2 | ⇒ |
rightarrow;
| U+02192 | → |
RightArrowBar;
| U+021E5 | ⇥ |
RightArrowLeftArrow;
| U+021C4 | ⇄ |
rightarrowtail;
| U+021A3 | ↣ |
RightCeiling;
| U+02309 | ⌉ |
RightDoubleBracket;
| U+027E7 | ⟧ |
RightDownTeeVector;
| U+0295D | ⥝ |
RightDownVector;
| U+021C2 | ⇂ |
RightDownVectorBar;
| U+02955 | ⥕ |
RightFloor;
| U+0230B | ⌋ |
rightharpoondown;
| U+021C1 | ⇁ |
rightharpoonup;
| U+021C0 | ⇀ |
rightleftarrows;
| U+021C4 | ⇄ |
rightleftharpoons;
| U+021CC | ⇌ |
rightrightarrows;
| U+021C9 | ⇉ |
rightsquigarrow;
| U+0219D | ↝ |
RightTee;
| U+022A2 | ⊢ |
RightTeeArrow;
| U+021A6 | ↦ |
RightTeeVector;
| U+0295B | ⥛ |
rightthreetimes;
| U+022CC | ⋌ |
RightTriangle;
| U+022B3 | ⊳ |
RightTriangleBar;
| U+029D0 | ⧐ |
RightTriangleEqual;
| U+022B5 | ⊵ |
RightUpDownVector;
| U+0294F | ⥏ |
RightUpTeeVector;
| U+0295C | ⥜ |
RightUpVector;
| U+021BE | ↾ |
RightUpVectorBar;
| U+02954 | ⥔ |
RightVector;
| U+021C0 | ⇀ |
RightVectorBar;
| U+02953 | ⥓ |
ring;
| U+002DA | ˚ |
risingdotseq;
| U+02253 | ≓ |
rlarr;
| U+021C4 | ⇄ |
rlhar;
| U+021CC | ⇌ |
rlm;
| U+0200F | |
rmoust;
| U+023B1 | ⎱ |
rmoustache;
| U+023B1 | ⎱ |
rnmid;
| U+02AEE | ⫮ |
roang;
| U+027ED | ⟭ |
roarr;
| U+021FE | ⇾ |
robrk;
| U+027E7 | ⟧ |
ropar;
| U+02986 | ⦆ |
Ropf;
| U+0211D | ℝ |
ropf;
| U+1D563 | 𝕣 |
roplus;
| U+02A2E | ⨮ |
rotimes;
| U+02A35 | ⨵ |
RoundImplies;
| U+02970 | ⥰ |
rpar;
| U+00029 | ) |
rpargt;
| U+02994 | ⦔ |
rppolint;
| U+02A12 | ⨒ |
rrarr;
| U+021C9 | ⇉ |
Rrightarrow;
| U+021DB | ⇛ |
rsaquo;
| U+0203A | › |
Rscr;
| U+0211B | ℛ |
rscr;
| U+1D4C7 | 𝓇 |
Rsh;
| U+021B1 | ↱ |
rsh;
| U+021B1 | ↱ |
rsqb;
| U+0005D | ] |
rsquo;
| U+02019 | ’ |
rsquor;
| U+02019 | ’ |
rthree;
| U+022CC | ⋌ |
rtimes;
| U+022CA | ⋊ |
rtri;
| U+025B9 | ▹ |
rtrie;
| U+022B5 | ⊵ |
rtrif;
| U+025B8 | ▸ |
rtriltri;
| U+029CE | ⧎ |
RuleDelayed;
| U+029F4 | ⧴ |
ruluhar;
| U+02968 | ⥨ |
rx;
| U+0211E | ℞ |
Sacute;
| U+0015A | Ś |
sacute;
| U+0015B | ś |
sbquo;
| U+0201A | ‚ |
Sc;
| U+02ABC | ⪼ |
sc;
| U+0227B | ≻ |
scap;
| U+02AB8 | ⪸ |
Scaron;
| U+00160 | Š |
scaron;
| U+00161 | š |
sccue;
| U+0227D | ≽ |
scE;
| U+02AB4 | ⪴ |
sce;
| U+02AB0 | ⪰ |
Scedil;
| U+0015E | Ş |
scedil;
| U+0015F | ş |
Scirc;
| U+0015C | Ŝ |
scirc;
| U+0015D | ŝ |
scnap;
| U+02ABA | ⪺ |
scnE;
| U+02AB6 | ⪶ |
scnsim;
| U+022E9 | ⋩ |
scpolint;
| U+02A13 | ⨓ |
scsim;
| U+0227F | ≿ |
Scy;
| U+00421 | С |
scy;
| U+00441 | с |
sdot;
| U+022C5 | ⋅ |
sdotb;
| U+022A1 | ⊡ |
sdote;
| U+02A66 | ⩦ |
searhk;
| U+02925 | ⤥ |
seArr;
| U+021D8 | ⇘ |
searr;
| U+02198 | ↘ |
searrow;
| U+02198 | ↘ |
sect;
| U+000A7 | § |
sect
| U+000A7 | § |
semi;
| U+0003B | ; |
seswar;
| U+02929 | ⤩ |
setminus;
| U+02216 | ∖ |
setmn;
| U+02216 | ∖ |
sext;
| U+02736 | ✶ |
Sfr;
| U+1D516 | 𝔖 |
sfr;
| U+1D530 | 𝔰 |
sfrown;
| U+02322 | ⌢ |
sharp;
| U+0266F | ♯ |
SHCHcy;
| U+00429 | Щ |
shchcy;
| U+00449 | щ |
SHcy;
| U+00428 | Ш |
shcy;
| U+00448 | ш |
ShortDownArrow;
| U+02193 | ↓ |
ShortLeftArrow;
| U+02190 | ← |
shortmid;
| U+02223 | ∣ |
shortparallel;
| U+02225 | ∥ |
ShortRightArrow;
| U+02192 | → |
ShortUpArrow;
| U+02191 | ↑ |
shy;
| U+000AD | |
shy
| U+000AD | |
Sigma;
| U+003A3 | Σ |
sigma;
| U+003C3 | σ |
sigmaf;
| U+003C2 | ς |
sigmav;
| U+003C2 | ς |
sim;
| U+0223C | ∼ |
simdot;
| U+02A6A | ⩪ |
sime;
| U+02243 | ≃ |
simeq;
| U+02243 | ≃ |
simg;
| U+02A9E | ⪞ |
simgE;
| U+02AA0 | ⪠ |
siml;
| U+02A9D | ⪝ |
simlE;
| U+02A9F | ⪟ |
simne;
| U+02246 | ≆ |
simplus;
| U+02A24 | ⨤ |
simrarr;
| U+02972 | ⥲ |
slarr;
| U+02190 | ← |
SmallCircle;
| U+02218 | ∘ |
smallsetminus;
| U+02216 | ∖ |
smashp;
| U+02A33 | ⨳ |
smeparsl;
| U+029E4 | ⧤ |
smid;
| U+02223 | ∣ |
smile;
| U+02323 | ⌣ |
smt;
| U+02AAA | ⪪ |
smte;
| U+02AAC | ⪬ |
smtes;
| U+02AAC U+0FE00 | ⪬︀ |
SOFTcy;
| U+0042C | Ь |
softcy;
| U+0044C | ь |
sol;
| U+0002F | / |
solb;
| U+029C4 | ⧄ |
solbar;
| U+0233F | ⌿ |
Sopf;
| U+1D54A | 𝕊 |
sopf;
| U+1D564 | 𝕤 |
spades;
| U+02660 | ♠ |
spadesuit;
| U+02660 | ♠ |
spar;
| U+02225 | ∥ |
sqcap;
| U+02293 | ⊓ |
sqcaps;
| U+02293 U+0FE00 | ⊓︀ |
sqcup;
| U+02294 | ⊔ |
sqcups;
| U+02294 U+0FE00 | ⊔︀ |
Sqrt;
| U+0221A | √ |
sqsub;
| U+0228F | ⊏ |
sqsube;
| U+02291 | ⊑ |
sqsubset;
| U+0228F | ⊏ |
sqsubseteq;
| U+02291 | ⊑ |
sqsup;
| U+02290 | ⊐ |
sqsupe;
| U+02292 | ⊒ |
sqsupset;
| U+02290 | ⊐ |
sqsupseteq;
| U+02292 | ⊒ |
squ;
| U+025A1 | □ |
Square;
| U+025A1 | □ |
square;
| U+025A1 | □ |
SquareIntersection;
| U+02293 | ⊓ |
SquareSubset;
| U+0228F | ⊏ |
SquareSubsetEqual;
| U+02291 | ⊑ |
SquareSuperset;
| U+02290 | ⊐ |
SquareSupersetEqual;
| U+02292 | ⊒ |
SquareUnion;
| U+02294 | ⊔ |
squarf;
| U+025AA | ▪ |
squf;
| U+025AA | ▪ |
srarr;
| U+02192 | → |
Sscr;
| U+1D4AE | 𝒮 |
sscr;
| U+1D4C8 | 𝓈 |
ssetmn;
| U+02216 | ∖ |
ssmile;
| U+02323 | ⌣ |
sstarf;
| U+022C6 | ⋆ |
Star;
| U+022C6 | ⋆ |
star;
| U+02606 | ☆ |
starf;
| U+02605 | ★ |
straightepsilon;
| U+003F5 | ϵ |
straightphi;
| U+003D5 | ϕ |
strns;
| U+000AF | ¯ |
Sub;
| U+022D0 | ⋐ |
sub;
| U+02282 | ⊂ |
subdot;
| U+02ABD | ⪽ |
subE;
| U+02AC5 | ⫅ |
sube;
| U+02286 | ⊆ |
subedot;
| U+02AC3 | ⫃ |
submult;
| U+02AC1 | ⫁ |
subnE;
| U+02ACB | ⫋ |
subne;
| U+0228A | ⊊ |
subplus;
| U+02ABF | ⪿ |
subrarr;
| U+02979 | ⥹ |
Subset;
| U+022D0 | ⋐ |
subset;
| U+02282 | ⊂ |
subseteq;
| U+02286 | ⊆ |
subseteqq;
| U+02AC5 | ⫅ |
SubsetEqual;
| U+02286 | ⊆ |
subsetneq;
| U+0228A | ⊊ |
subsetneqq;
| U+02ACB | ⫋ |
subsim;
| U+02AC7 | ⫇ |
subsub;
| U+02AD5 | ⫕ |
subsup;
| U+02AD3 | ⫓ |
succ;
| U+0227B | ≻ |
succapprox;
| U+02AB8 | ⪸ |
succcurlyeq;
| U+0227D | ≽ |
Succeeds;
| U+0227B | ≻ |
SucceedsEqual;
| U+02AB0 | ⪰ |
SucceedsSlantEqual;
| U+0227D | ≽ |
SucceedsTilde;
| U+0227F | ≿ |
succeq;
| U+02AB0 | ⪰ |
succnapprox;
| U+02ABA | ⪺ |
succneqq;
| U+02AB6 | ⪶ |
succnsim;
| U+022E9 | ⋩ |
succsim;
| U+0227F | ≿ |
SuchThat;
| U+0220B | ∋ |
Sum;
| U+02211 | ∑ |
sum;
| U+02211 | ∑ |
sung;
| U+0266A | ♪ |
Sup;
| U+022D1 | ⋑ |
sup;
| U+02283 | ⊃ |
sup1;
| U+000B9 | ¹ |
sup1
| U+000B9 | ¹ |
sup2;
| U+000B2 | ² |
sup2
| U+000B2 | ² |
sup3;
| U+000B3 | ³ |
sup3
| U+000B3 | ³ |
supdot;
| U+02ABE | ⪾ |
supdsub;
| U+02AD8 | ⫘ |
supE;
| U+02AC6 | ⫆ |
supe;
| U+02287 | ⊇ |
supedot;
| U+02AC4 | ⫄ |
Superset;
| U+02283 | ⊃ |
SupersetEqual;
| U+02287 | ⊇ |
suphsol;
| U+027C9 | ⟉ |
suphsub;
| U+02AD7 | ⫗ |
suplarr;
| U+0297B | ⥻ |
supmult;
| U+02AC2 | ⫂ |
supnE;
| U+02ACC | ⫌ |
supne;
| U+0228B | ⊋ |
supplus;
| U+02AC0 | ⫀ |
Supset;
| U+022D1 | ⋑ |
supset;
| U+02283 | ⊃ |
supseteq;
| U+02287 | ⊇ |
supseteqq;
| U+02AC6 | ⫆ |
supsetneq;
| U+0228B | ⊋ |
supsetneqq;
| U+02ACC | ⫌ |
supsim;
| U+02AC8 | ⫈ |
supsub;
| U+02AD4 | ⫔ |
supsup;
| U+02AD6 | ⫖ |
swarhk;
| U+02926 | ⤦ |
swArr;
| U+021D9 | ⇙ |
swarr;
| U+02199 | ↙ |
swarrow;
| U+02199 | ↙ |
swnwar;
| U+0292A | ⤪ |
szlig;
| U+000DF | ß |
szlig
| U+000DF | ß |
Tab;
| U+00009 | ␉ |
target;
| U+02316 | ⌖ |
Tau;
| U+003A4 | Τ |
tau;
| U+003C4 | τ |
tbrk;
| U+023B4 | ⎴ |
Tcaron;
| U+00164 | Ť |
tcaron;
| U+00165 | ť |
Tcedil;
| U+00162 | Ţ |
tcedil;
| U+00163 | ţ |
Tcy;
| U+00422 | Т |
tcy;
| U+00442 | т |
tdot;
| U+020DB | ◌⃛ |
telrec;
| U+02315 | ⌕ |
Tfr;
| U+1D517 | 𝔗 |
tfr;
| U+1D531 | 𝔱 |
there4;
| U+02234 | ∴ |
Therefore;
| U+02234 | ∴ |
therefore;
| U+02234 | ∴ |
Theta;
| U+00398 | Θ |
theta;
| U+003B8 | θ |
thetasym;
| U+003D1 | ϑ |
thetav;
| U+003D1 | ϑ |
thickapprox;
| U+02248 | ≈ |
thicksim;
| U+0223C | ∼ |
ThickSpace;
| U+0205F U+0200A | |
thinsp;
| U+02009 | |
ThinSpace;
| U+02009 | |
thkap;
| U+02248 | ≈ |
thksim;
| U+0223C | ∼ |
THORN;
| U+000DE | Þ |
THORN
| U+000DE | Þ |
thorn;
| U+000FE | þ |
thorn
| U+000FE | þ |
Tilde;
| U+0223C | ∼ |
tilde;
| U+002DC | ˜ |
TildeEqual;
| U+02243 | ≃ |
TildeFullEqual;
| U+02245 | ≅ |
TildeTilde;
| U+02248 | ≈ |
times;
| U+000D7 | × |
times
| U+000D7 | × |
timesb;
| U+022A0 | ⊠ |
timesbar;
| U+02A31 | ⨱ |
timesd;
| U+02A30 | ⨰ |
tint;
| U+0222D | ∭ |
toea;
| U+02928 | ⤨ |
top;
| U+022A4 | ⊤ |
topbot;
| U+02336 | ⌶ |
topcir;
| U+02AF1 | ⫱ |
Topf;
| U+1D54B | 𝕋 |
topf;
| U+1D565 | 𝕥 |
topfork;
| U+02ADA | ⫚ |
tosa;
| U+02929 | ⤩ |
tprime;
| U+02034 | ‴ |
TRADE;
| U+02122 | ™ |
trade;
| U+02122 | ™ |
triangle;
| U+025B5 | ▵ |
triangledown;
| U+025BF | ▿ |
triangleleft;
| U+025C3 | ◃ |
trianglelefteq;
| U+022B4 | ⊴ |
triangleq;
| U+0225C | ≜ |
triangleright;
| U+025B9 | ▹ |
trianglerighteq;
| U+022B5 | ⊵ |
tridot;
| U+025EC | ◬ |
trie;
| U+0225C | ≜ |
triminus;
| U+02A3A | ⨺ |
TripleDot;
| U+020DB | ◌⃛ |
triplus;
| U+02A39 | ⨹ |
trisb;
| U+029CD | ⧍ |
tritime;
| U+02A3B | ⨻ |
trpezium;
| U+023E2 | ⏢ |
Tscr;
| U+1D4AF | 𝒯 |
tscr;
| U+1D4C9 | 𝓉 |
TScy;
| U+00426 | Ц |
tscy;
| U+00446 | ц |
TSHcy;
| U+0040B | Ћ |
tshcy;
| U+0045B | ћ |
Tstrok;
| U+00166 | Ŧ |
tstrok;
| U+00167 | ŧ |
twixt;
| U+0226C | ≬ |
twoheadleftarrow;
| U+0219E | ↞ |
twoheadrightarrow;
| U+021A0 | ↠ |
Uacute;
| U+000DA | Ú |
Uacute
| U+000DA | Ú |
uacute;
| U+000FA | ú |
uacute
| U+000FA | ú |
Uarr;
| U+0219F | ↟ |
uArr;
| U+021D1 | ⇑ |
uarr;
| U+02191 | ↑ |
Uarrocir;
| U+02949 | ⥉ |
Ubrcy;
| U+0040E | Ў |
ubrcy;
| U+0045E | ў |
Ubreve;
| U+0016C | Ŭ |
ubreve;
| U+0016D | ŭ |
Ucirc;
| U+000DB | Û |
Ucirc
| U+000DB | Û |
ucirc;
| U+000FB | û |
ucirc
| U+000FB | û |
Ucy;
| U+00423 | У |
ucy;
| U+00443 | у |
udarr;
| U+021C5 | ⇅ |
Udblac;
| U+00170 | Ű |
udblac;
| U+00171 | ű |
udhar;
| U+0296E | ⥮ |
ufisht;
| U+0297E | ⥾ |
Ufr;
| U+1D518 | 𝔘 |
ufr;
| U+1D532 | 𝔲 |
Ugrave;
| U+000D9 | Ù |
Ugrave
| U+000D9 | Ù |
ugrave;
| U+000F9 | ù |
ugrave
| U+000F9 | ù |
uHar;
| U+02963 | ⥣ |
uharl;
| U+021BF | ↿ |
uharr;
| U+021BE | ↾ |
uhblk;
| U+02580 | ▀ |
ulcorn;
| U+0231C | ⌜ |
ulcorner;
| U+0231C | ⌜ |
ulcrop;
| U+0230F | ⌏ |
ultri;
| U+025F8 | ◸ |
Umacr;
| U+0016A | Ū |
umacr;
| U+0016B | ū |
uml;
| U+000A8 | ¨ |
uml
| U+000A8 | ¨ |
UnderBar;
| U+0005F | _ |
UnderBrace;
| U+023DF | ⏟ |
UnderBracket;
| U+023B5 | ⎵ |
UnderParenthesis;
| U+023DD | ⏝ |
Union;
| U+022C3 | ⋃ |
UnionPlus;
| U+0228E | ⊎ |
Uogon;
| U+00172 | Ų |
uogon;
| U+00173 | ų |
Uopf;
| U+1D54C | 𝕌 |
uopf;
| U+1D566 | 𝕦 |
UpArrow;
| U+02191 | ↑ |
Uparrow;
| U+021D1 | ⇑ |
uparrow;
| U+02191 | ↑ |
UpArrowBar;
| U+02912 | ⤒ |
UpArrowDownArrow;
| U+021C5 | ⇅ |
UpDownArrow;
| U+02195 | ↕ |
Updownarrow;
| U+021D5 | ⇕ |
updownarrow;
| U+02195 | ↕ |
UpEquilibrium;
| U+0296E | ⥮ |
upharpoonleft;
| U+021BF | ↿ |
upharpoonright;
| U+021BE | ↾ |
uplus;
| U+0228E | ⊎ |
UpperLeftArrow;
| U+02196 | ↖ |
UpperRightArrow;
| U+02197 | ↗ |
Upsi;
| U+003D2 | ϒ |
upsi;
| U+003C5 | υ |
upsih;
| U+003D2 | ϒ |
Upsilon;
| U+003A5 | Υ |
upsilon;
| U+003C5 | υ |
UpTee;
| U+022A5 | ⊥ |
UpTeeArrow;
| U+021A5 | ↥ |
upuparrows;
| U+021C8 | ⇈ |
urcorn;
| U+0231D | ⌝ |
urcorner;
| U+0231D | ⌝ |
urcrop;
| U+0230E | ⌎ |
Uring;
| U+0016E | Ů |
uring;
| U+0016F | ů |
urtri;
| U+025F9 | ◹ |
Uscr;
| U+1D4B0 | 𝒰 |
uscr;
| U+1D4CA | 𝓊 |
utdot;
| U+022F0 | ⋰ |
Utilde;
| U+00168 | Ũ |
utilde;
| U+00169 | ũ |
utri;
| U+025B5 | ▵ |
utrif;
| U+025B4 | ▴ |
uuarr;
| U+021C8 | ⇈ |
Uuml;
| U+000DC | Ü |
Uuml
| U+000DC | Ü |
uuml;
| U+000FC | ü |
uuml
| U+000FC | ü |
uwangle;
| U+029A7 | ⦧ |
vangrt;
| U+0299C | ⦜ |
varepsilon;
| U+003F5 | ϵ |
varkappa;
| U+003F0 | ϰ |
varnothing;
| U+02205 | ∅ |
varphi;
| U+003D5 | ϕ |
varpi;
| U+003D6 | ϖ |
varpropto;
| U+0221D | ∝ |
vArr;
| U+021D5 | ⇕ |
varr;
| U+02195 | ↕ |
varrho;
| U+003F1 | ϱ |
varsigma;
| U+003C2 | ς |
varsubsetneq;
| U+0228A U+0FE00 | ⊊︀ |
varsubsetneqq;
| U+02ACB U+0FE00 | ⫋︀ |
varsupsetneq;
| U+0228B U+0FE00 | ⊋︀ |
varsupsetneqq;
| U+02ACC U+0FE00 | ⫌︀ |
vartheta;
| U+003D1 | ϑ |
vartriangleleft;
| U+022B2 | ⊲ |
vartriangleright;
| U+022B3 | ⊳ |
Vbar;
| U+02AEB | ⫫ |
vBar;
| U+02AE8 | ⫨ |
vBarv;
| U+02AE9 | ⫩ |
Vcy;
| U+00412 | В |
vcy;
| U+00432 | в |
VDash;
| U+022AB | ⊫ |
Vdash;
| U+022A9 | ⊩ |
vDash;
| U+022A8 | ⊨ |
vdash;
| U+022A2 | ⊢ |
Vdashl;
| U+02AE6 | ⫦ |
Vee;
| U+022C1 | ⋁ |
vee;
| U+02228 | ∨ |
veebar;
| U+022BB | ⊻ |
veeeq;
| U+0225A | ≚ |
vellip;
| U+022EE | ⋮ |
Verbar;
| U+02016 | ‖ |
verbar;
| U+0007C | | |
Vert;
| U+02016 | ‖ |
vert;
| U+0007C | | |
VerticalBar;
| U+02223 | ∣ |
VerticalLine;
| U+0007C | | |
VerticalSeparator;
| U+02758 | ❘ |
VerticalTilde;
| U+02240 | ≀ |
VeryThinSpace;
| U+0200A | |
Vfr;
| U+1D519 | 𝔙 |
vfr;
| U+1D533 | 𝔳 |
vltri;
| U+022B2 | ⊲ |
vnsub;
| U+02282 U+020D2 | ⊂⃒ |
vnsup;
| U+02283 U+020D2 | ⊃⃒ |
Vopf;
| U+1D54D | 𝕍 |
vopf;
| U+1D567 | 𝕧 |
vprop;
| U+0221D | ∝ |
vrtri;
| U+022B3 | ⊳ |
Vscr;
| U+1D4B1 | 𝒱 |
vscr;
| U+1D4CB | 𝓋 |
vsubnE;
| U+02ACB U+0FE00 | ⫋︀ |
vsubne;
| U+0228A U+0FE00 | ⊊︀ |
vsupnE;
| U+02ACC U+0FE00 | ⫌︀ |
vsupne;
| U+0228B U+0FE00 | ⊋︀ |
Vvdash;
| U+022AA | ⊪ |
vzigzag;
| U+0299A | ⦚ |
Wcirc;
| U+00174 | Ŵ |
wcirc;
| U+00175 | ŵ |
wedbar;
| U+02A5F | ⩟ |
Wedge;
| U+022C0 | ⋀ |
wedge;
| U+02227 | ∧ |
wedgeq;
| U+02259 | ≙ |
weierp;
| U+02118 | ℘ |
Wfr;
| U+1D51A | 𝔚 |
wfr;
| U+1D534 | 𝔴 |
Wopf;
| U+1D54E | 𝕎 |
wopf;
| U+1D568 | 𝕨 |
wp;
| U+02118 | ℘ |
wr;
| U+02240 | ≀ |
wreath;
| U+02240 | ≀ |
Wscr;
| U+1D4B2 | 𝒲 |
wscr;
| U+1D4CC | 𝓌 |
xcap;
| U+022C2 | ⋂ |
xcirc;
| U+025EF | ◯ |
xcup;
| U+022C3 | ⋃ |
xdtri;
| U+025BD | ▽ |
Xfr;
| U+1D51B | 𝔛 |
xfr;
| U+1D535 | 𝔵 |
xhArr;
| U+027FA | ⟺ |
xharr;
| U+027F7 | ⟷ |
Xi;
| U+0039E | Ξ |
xi;
| U+003BE | ξ |
xlArr;
| U+027F8 | ⟸ |
xlarr;
| U+027F5 | ⟵ |
xmap;
| U+027FC | ⟼ |
xnis;
| U+022FB | ⋻ |
xodot;
| U+02A00 | ⨀ |
Xopf;
| U+1D54F | 𝕏 |
xopf;
| U+1D569 | 𝕩 |
xoplus;
| U+02A01 | ⨁ |
xotime;
| U+02A02 | ⨂ |
xrArr;
| U+027F9 | ⟹ |
xrarr;
| U+027F6 | ⟶ |
Xscr;
| U+1D4B3 | 𝒳 |
xscr;
| U+1D4CD | 𝓍 |
xsqcup;
| U+02A06 | ⨆ |
xuplus;
| U+02A04 | ⨄ |
xutri;
| U+025B3 | △ |
xvee;
| U+022C1 | ⋁ |
xwedge;
| U+022C0 | ⋀ |
Yacute;
| U+000DD | Ý |
Yacute
| U+000DD | Ý |
yacute;
| U+000FD | ý |
yacute
| U+000FD | ý |
YAcy;
| U+0042F | Я |
yacy;
| U+0044F | я |
Ycirc;
| U+00176 | Ŷ |
ycirc;
| U+00177 | ŷ |
Ycy;
| U+0042B | Ы |
ycy;
| U+0044B | ы |
yen;
| U+000A5 | ¥ |
yen
| U+000A5 | ¥ |
Yfr;
| U+1D51C | 𝔜 |
yfr;
| U+1D536 | 𝔶 |
YIcy;
| U+00407 | Ї |
yicy;
| U+00457 | ї |
Yopf;
| U+1D550 | 𝕐 |
yopf;
| U+1D56A | 𝕪 |
Yscr;
| U+1D4B4 | 𝒴 |
yscr;
| U+1D4CE | 𝓎 |
YUcy;
| U+0042E | Ю |
yucy;
| U+0044E | ю |
Yuml;
| U+00178 | Ÿ |
yuml;
| U+000FF | ÿ |
yuml
| U+000FF | ÿ |
Zacute;
| U+00179 | Ź |
zacute;
| U+0017A | ź |
Zcaron;
| U+0017D | Ž |
zcaron;
| U+0017E | ž |
Zcy;
| U+00417 | З |
zcy;
| U+00437 | з |
Zdot;
| U+0017B | Ż |
zdot;
| U+0017C | ż |
zeetrf;
| U+02128 | ℨ |
ZeroWidthSpace;
| U+0200B | |
Zeta;
| U+00396 | Ζ |
zeta;
| U+003B6 | ζ |
Zfr;
| U+02128 | ℨ |
zfr;
| U+1D537 | 𝔷 |
ZHcy;
| U+00416 | Ж |
zhcy;
| U+00436 | ж |
zigrarr;
| U+021DD | ⇝ |
Zopf;
| U+02124 | ℤ |
zopf;
| U+1D56B | 𝕫 |
Zscr;
| U+1D4B5 | 𝒵 |
zscr;
| U+1D4CF | 𝓏 |
zwj;
| U+0200D | |
zwnj;
| U+0200C | |
This data is also available as a JSON file.
The glyphs displayed above are non-normative. Refer to the Unicode specifications for formal definitions of the characters listed above.
The character reference names originate from the XML Entity Definitions for Characters specification, though only the above is considered normative. [[XML-ENTITY-NAMES]]
9. The XHTML syntax
This section only describes the rules for XML resources. Rules for text/html
resources are discussed in the section above entitled "The HTML syntax".
The syntax for using HTML with XML, whether in XHTML documents or embedded in other XML documents, is defined in the XML and Namespaces in XML specifications. [XML] [XML-NAMES]
This specification does not define any syntax-level requirements beyond those defined for XML proper.
XML documents may contain a DOCTYPE
if desired, but this is not required
to conform to this specification. This specification does not define a public or system
identifier, nor provide a formal DTD.
According to the XML specification, XML processors are not guaranteed to process
the external DTD subset referenced in the DOCTYPE. This means, for example, that using entity references for characters in XHTML documents
is unsafe if they are defined in an external file (except for <
, >
, &
, "
and '
).
9.2. Parsing XHTML documents
This section describes the relationship between XML and the DOM, with a particular emphasis on how this interacts with HTML.
An XML parser, for the purposes of this specification, is a construct that follows
the rules given in the XML specification to map a string of bytes or characters into a Document
object.
At the time of writing, no such rules actually exist.
An XML parser is either associated with a Document
object when it is
created, or creates one implicitly.
This Document
must then be populated with DOM nodes that represent the tree
structure of the input passed to the parser, as defined by the XML specification, the Namespaces
in XML specification, and the DOM specification. DOM mutation events must not fire for the
operations that the XML parser performs on the Document
’s tree, but the
user agent must act as if elements and attributes were individually appended and set respectively
so as to trigger rules in this specification regarding what happens when an element is inserted
into a document or has its attributes set, and the DOM specification’s requirements regarding
mutation observers mean that mutation observers are fired (unlike mutation events). [XML] [XML-NAMES] [DOM] [UIEVENTS]
Between the time an element’s start tag is parsed and the time either the element’s end tag is parsed or the parser detects a well-formedness error, the user agent must act as if the element was in a stack of open elements.
This is used, e.g., by the object
element to avoid instantiating plugins
before the param
element children have been parsed.
This specification provides the following additional information that user agents should use when retrieving an external entity: the public identifiers given in the following list all correspond to the URL given by this link. (This URL is a DTD containing the entity declarations for the names listed in the §8.5 Named character references section.) [XML]
-//W3C//DTD XHTML 1.0 Transitional//EN
-//W3C//DTD XHTML 1.1//EN
-//W3C//DTD XHTML 1.0 Strict//EN
-//W3C//DTD XHTML 1.0 Frameset//EN
-//W3C//DTD XHTML Basic 1.0//EN
-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN
-//W3C//DTD XHTML 1.1 plus MathML 2.0 plus SVG 1.1//EN
-//W3C//DTD MathML 2.0//EN
-//WAPFORUM//DTD XHTML Mobile 1.0//EN
Furthermore, user agents should attempt to retrieve the above external entity’s content when one of the above public identifiers is used, and should not attempt to retrieve any other external entity’s content.
This is not strictly a violation of the XML specification, but it does contradict the spirit of the XML specification’s requirements. This is motivated by a desire for user agents to all handle entities in an interoperable fashion without requiring any network access for handling external subsets. [XML]
XML parsers can be invoked with XML scripting support enabled or disabled. Except where otherwise specified, XML parsers are invoked with XML scripting support enabled.
When an XML parser with XML scripting support enabled creates a script
element, it
must be marked as being "parser-inserted" and its "non-blocking" flag
must be unset. If the parser was originally created for the XML fragment parsing
algorithm, then the element must be marked as "already started" also. When the
element’s end tag is subsequently parsed, the user agent must perform a microtask checkpoint, and
then prepare the script
element. If this
causes there to be a pending parsing-blocking script, then the user agent must run
the following steps:
- Block this instance of the XML parser, such that the event loop will not run tasks that invoke it.
- Spin the event loop until the parser’s
Document
has no style sheet that is blocking scripts and the pending parsing-blocking script’s "ready to be parser-executed" flag is set. - Unblock this instance of the XML parser, such that tasks that invoke it can again be run.
- Execute the pending parsing-blocking script.
- There is no longer a pending parsing-blocking script.
Since the document.write()
API is not
available for XML documents, much of the complexity in the HTML parser is not needed in the XML parser.
When the XML parser has XML scripting support disabled, none of this happens.
When an XML parser would append a node to a template
element, it must instead append it to the template
element’s template contents (a DocumentFragment
node).
This is a willful violation of the XML specification; unfortunately,
XML is not formally extensible in the manner that is needed for template
processing. [XML]
When an XML parser creates a Node
object, its node document must be set to the node document of
the node into which the newly created node is to be inserted.
Certain algorithms in this specification spoon-feed the parser characters one string at a time. In such cases, the XML parser must act as it would have if faced with a single string consisting of the concatenation of all those characters.
When an XML parser reaches the end of its input, it must stop parsing, following the same rules as the HTML parser. An XML parser can also be aborted, which must again be done in the same way as for an HTML parser.
For the purposes of conformance checkers, if a resource is determined to be in the XHTML syntax, then it is an XML document.
9.3. Serializing XHTML fragments
The XML fragment serialization algorithm for a Document
or Element
node either returns a fragment of XML that represents that node or throws an
exception.
For Document
s, the algorithm must return a string in the form of a document entity, if none of the error cases
below apply.
For Element
s, the algorithm must return a string in the form of an internal general parsed entity, if none of the
error cases below apply.
In both cases, the string returned must be XML namespace-well-formed and must be an isomorphic
serialization of all of that node’s relevant child nodes, in tree order.
User agents may adjust prefixes and namespace declarations in the serialization (and indeed might
be forced to do so in some cases to obtain namespace-well-formed XML). User agents may use a
combination of regular text and character references to represent Text
nodes in the
DOM.
A node’s relevant child nodes are those that apply given the following rules:
- For
template
elements - The relevant child nodes are the child nodes of the
template
element’s template contents, if any. - For all other nodes
- The relevant child nodes are the child nodes of node itself, if any.
For Element
s, if any of the elements in the serialization are in no namespace, the
default namespace in scope for those elements must be explicitly declared as the empty string. (This doesn’t apply in the Document
case.) [XML] [XML-NAMES]
For the purposes of this section, an internal general parsed entity is considered XML namespace-well-formed if a document consisting of an element with no namespace declarations whose contents are the internal general parsed entity would itself be XML namespace-well-formed.
If any of the following error cases are found in the DOM subtree being serialized, then the
algorithm must throw an InvalidStateError
exception instead of returning a
string:
- A
Document
node with no child element nodes. - A
DocumentType
node that has an external subset public identifier that contains characters that are not matched by the XMLPubidChar
production. [XML] - A
DocumentType
node that has an external subset system identifier that contains both a U+0022 QUOTATION MARK (") and a U+0027 APOSTROPHE (') or that contains characters that are not matched by the XMLChar
production. [XML] - A node with a local name containing a U+003A COLON (:).
- A node with a local name that does not match the XML
Name
production. [XML] - An
Attr
node with no namespace whose local name is the lowercase string "xmlns
". [XML-NAMES] - An
Element
node with two or more attributes with the same local name and namespace. - An
Attr
node,Text
node,Comment
node, orProcessingInstruction
node whose data contains characters that are not matched by the XMLChar
production. [XML] - A
Comment
node whose data contains two adjacent U+002D HYPHEN-MINUS characters (-) or ends with such a character. - A
ProcessingInstruction
node whose target name is an ASCII case-insensitive match for the string "xml
". - A
ProcessingInstruction
node whose target name contains a U+003A COLON (:). - A
ProcessingInstruction
node whose data contains the string "?>
".
These are the only ways to make a DOM unserialisable. The DOM enforces all the
other XML constraints; for example, trying to append two elements to a Document
node
will throw a HierarchyRequestError
exception.
9.4. Parsing XHTML fragments
The XML fragment parsing algorithm either returns a Document
or throws
a "SyntaxError
" DOMException
. Given a string input and a
context element context, the algorithm is as
follows:
-
Create a new XML parser.
-
Feed the parser just created the string corresponding to the start tag of the context element, declaring all the namespace prefixes that are in scope on that element in the DOM, as well as declaring the default namespace (if any) that is in scope on that element in the DOM.
A namespace prefix is in scope if the DOM
lookupNamespaceURI()
method on the element would return a non-null value for that prefix.The default namespace is the namespace for which the DOM
isDefaultNamespace()
method on the element would return true.No
DOCTYPE
is passed to the parser, and therefore no external subset is referenced, and therefore no entities will be recognized. -
Feed the parser just created the string input.
-
Feed the parser just created the string corresponding to the end tag of the context element.
-
If there is an XML well-formedness or XML namespace well-formedness error, then throw a "
SyntaxError
"DOMException
and abort these steps. -
If the root element of the resulting
Document
has any sibling nodes, then throw a "SyntaxError
"DOMException
and abort these steps. -
Return the child nodes of the root element of the resulting
Document
, in tree order.
10. Rendering
User agents are not required to present HTML documents in any particular way. However, this section provides a set of suggestions for rendering HTML documents that, if followed, are likely to lead to a user experience that closely resembles the experience intended by the documents' authors. So as to avoid confusion regarding the normativity of this section, RFC2119 terms have not been used. Instead, the term "expected" is used to indicate behavior that will lead to this experience. For the purposes of conformance for user agents designated as supporting the suggested default rendering, the term "expected" in this section has the same conformance implications as the RFC2119-defined term "must".
10.1. Introduction
In general, user agents are expected to support CSS, and many of the suggestions in this section are expressed in CSS terms. User agents that use other presentation mechanisms can derive their expected behavior by translating from the CSS rules given in this section.
In the absence of style-layer rules to the contrary (e.g., author style sheets), user agents are expected to render an element so that it conveys to the user the meaning that the element represents, as described by this specification.
The suggestions in this section generally assume a visual output medium with a resolution of 96dpi or greater, but HTML is intended to apply to multiple media (it is a media-independent language). User agent implementors are encouraged to adapt the suggestions in this section to their target media.
An element is being rendered if it has any associated CSS layout boxes, SVG layout boxes, or some equivalent in other styling languages.
Just being off-screen does not mean the element is not being
rendered. The presence of the hidden
attribute normally
means the element is not being rendered, though this might be overridden by the style
sheets.
User agents that do not honor author-level CSS style sheets are nonetheless expected to act as if they applied the CSS rules given in these sections in a manner consistent with this specification and the relevant CSS and Unicode specifications. [CSS-2015] [UNICODE] [BIDI]
This is especially important for issues relating to the display, unicode-bidi, and direction properties.
10.2. The CSS user agent style sheet and presentational hints
The CSS rules given in these subsections are, except where otherwise specified, expected to be used as part of the user-agent level style sheet defaults for all documents that contain html elements.
Some rules are intended for the author-level zero-specificity presentational hints part of the CSS cascade; these are explicitly called out as presentational hints.
Some of the rules regarding left and right margins are given here as appropriate for elements whose direction property is ltr, and are expected to be flipped around on elements whose direction property is rtl. These are marked "LTR-specific".
These markings only affect the handling of attribute values, not attribute names or element names.
When the text below says that an attribute attribute on an element element maps to the pixel length property (or properties) properties, it means that if element has an attribute attribute set, and parsing that attribute’s value using the rules for parsing non-negative integers doesn’t generate an error, then the user agent is expected to use the parsed value as a pixel length for a presentational hint for properties.
When the text below says that an attribute attribute on an element element maps to the dimension property (or properties) properties, it means that if element has an attribute attribute set, and parsing that attribute’s value using the rules for parsing dimension values doesn’t generate an error, then the user agent is expected to use the parsed dimension as the value for a presentational hint for properties, with the value given as a pixel length if the dimension was a length, and with the value given as a percentage if the dimension was a percentage.
When the text below says that an attribute attribute on an element element maps to the dimension property (ignoring zero) (or properties) properties, it means that if element has an attribute attribute set, and parsing that attribute’s value using the rules for parsing non-zero dimension values doesn’t generate an error, then the user agent is expected to use the parsed dimension as the value for a presentational hint for properties, with the value given as a pixel length if the dimension was a length, and with the value given as a percentage if the dimension was a percentage.
When a user agent is to align descendants of a node, the user agent is expected to
align only those descendants that have both their margin-left and margin-right properties
computing to a value other than auto
, that are over-constrained and that have one of those two
margins with a used value forced to a greater value, and that do not themselves have an applicable align
attribute. When multiple elements are to align a particular descendant, the most deeply nested such
element is expected to override the others. Aligned elements are expected to be aligned by having
the used values of their left and right margins be set accordingly.
10.3. Non-replaced elements
10.3.1. Hidden elements
@namespace url(http://www.w3.org/1999/xhtml); [hidden], area, base, basefont, datalist, head, link, menu[type=context i], meta, noembed, noframes, param, rp, script, source, style, template, track, title { display: none; } embed[hidden] { display: inline; height: 0; width: 0; } input[type=hidden i] { display none ! important; } @media (scripting) { noscript { display: none !important; } }
10.3.2. The page
@namespace url(http://www.w3.org/1999/xhtml); html, body { display: block; }
For each property in the table below, given a body
element, the first attribute
that exists maps to the pixel length property on the body
element. If
none of the attributes for a property are found, or if the value of the attribute that was found
cannot be parsed successfully, then, then a default value of 8px is expected to be used for that
property instead.
Property | Source |
---|---|
margin-top | body element’s marginheight attribute
|
The body element’s container frame element’s marginheight attribute
| |
body element’s topmargin attribute
| |
margin-right | body element’s marginwidth attribute
|
The body element’s container frame element’s marginwidth attribute
| |
body element’s rightmargin attribute
| |
margin-bottom | body element’s marginheight attribute
|
The body element’s container frame element’s marginheight attribute
| |
body element’s bottommargin attribute
| |
margin-left | body element’s marginwidth attribute
|
The body element’s container frame element’s marginwidth attribute
| |
body element’s leftmargin attribute
|
If the body
element’s node document’s browsing context is a nested browsing context, and the browsing context container of that nested browsing context is a frame
or iframe
element, then
the container frame element of the body
element is that frame
or iframe
element. Otherwise, there is no container frame element.
The above requirements imply that a page can change the margins of another page
(including one from another origin) using, for example, an iframe
. This
is potentially a security risk, as it might in some cases allow an attack to contrive a situation
in which a page is rendered not as the author intended, possibly for the purposes of phishing or
otherwise misleading the user.
If a Document
is in a nested browsing context, it is expected to be
positioned and sized to fit inside the content box of its browsing context container.
If a browsing context is not being rendered, it is expected to have a viewport with zero width and zero height.
If the Document
is in a nested browsing context, and the browsing context container of that nested browsing context is a frame
or iframe
element, and that element has a scrolling
attribute, and that attribute’s value is an ASCII
case-insensitive match for the string "off
", "noscroll
", or "no
", then the user agent is expected to
prevent any scroll bars from being shown for the viewport of the nested browsing context, regardless of the overflow property that applies to that viewport.
When a body
element has a background
attribute set to a non-empty value, the new value is expected to be parsed relative to the
element’s node document, and if this is successful, the user agent is
expected to treat the attribute as a presentational hint setting the element’s background-image property to the resulting URL string.
When a body
element has a bgcolor
attribute
set, the new value is expected to be parsed using the rules for parsing a legacy color
value, and if that does not return an error, the user agent is expected to treat the
attribute as a presentational hint setting the element’s background-color property to the resulting color.
When a body
element has a text
attribute, its
value is expected to be parsed using the rules for parsing a legacy color value, and
if that does not return an error, the user agent is expected to treat the attribute as a presentational hint setting the element’s color property to
the resulting color.
When a body
element has a link
attribute, its
value is expected to be parsed using the rules for parsing a legacy color value, and
if that does not return an error, the user agent is expected to treat the attribute as a presentational hint setting the color property of any
element in the Document
matching the ':link' pseudo-class to the resulting color.
When a body
element has a vlink
attribute,
its value is expected to be parsed using the rules for parsing a legacy color value,
and if that does not return an error, the user agent is expected to treat the attribute as a presentational hint setting the color property of any
element in the Document
matching the ':visited' pseudo-class to the resulting
color.
When a body
element has an alink
attribute,
its value is expected to be parsed using the rules for parsing a legacy color value,
and if that does not return an error, the user agent is expected to treat the attribute as a presentational hint setting the color property of any
element in the Document
matching the ':active' pseudo-class and either the ':link'
pseudo-class or the ':visited' pseudo-class to the resulting color.
10.3.3. Flow content
@namespace url(http://www.w3.org/1999/xhtml); address, blockquote, center, div, figure, figcaption, footer, form, header, hr, legend, listing, main, p, plaintext, pre, summary, xmp { display: block; } blockquote, figure, listing, p, plaintext, pre, xmp { margin-top: 1em; margin-bottom: 1em; } blockquote, figure { margin-left: 40px; margin-right: 40px; } address { font-style: italic; } listing, plaintext, pre, xmp { font-family: monospace; white-space: pre; }
The following rules are also expected to apply, as presentational hints:
@namespace url(http://www.w3.org/1999/xhtml); pre[wrap] { white-space: pre-wrap; }
In quirks mode, the following rules are also expected to apply:
@namespace url(http://www.w3.org/1999/xhtml); form { margin-bottom: 1em; }
The center
element, and the div
element when it has an align
attribute whose value is an ASCII
case-insensitive match for either the string "center
" or the string
"middle
", are expected to center text within themselves, as if they had
their text-align property set to center in a presentational hint, and to align descendants to the center.
The div
element, when it has an align
attribute whose value is an ASCII case-insensitive match for the string "left
", is expected to left-align text within itself, as if it had its text-align property set to left in a presentational
hint, and to align descendants to the left.
The div
element, when it has an align
attribute whose value is an ASCII case-insensitive match for the string "right
", is expected to right-align text within itself, as if it had its text-align property set to right in a presentational
hint, and to align descendants to the right.
The div
element, when it has an align
attribute whose value is an ASCII case-insensitive match for the string "justify
", is expected to full-justify text within itself, as if it had its text-align property set to justify in a presentational
hint, and to align descendants to the left.
10.3.4. Phrasing content
@namespace url(http://www.w3.org/1999/xhtml); cite, dfn, em, i, var { font-style: italic; } b, strong { font-weight: bolder; } code, kbd, samp, tt { font-family: monospace; } big { font-size: larger; } small { font-size: smaller; } sub { vertical-align: sub; } sup { vertical-align: super; } sub, sup { line-height: normal; font-size: smaller; } ruby { display: ruby; } rb { display: ruby-base; white-space: nowrap; } rt { display: ruby-text; white-space: nowrap; font-size: 50%; font-variant-east-asian: ruby; text-emphasis: none; } rbc { display: ruby-base-container; } rtc { display: ruby-text-container; } ruby, rb, rt, rbc, rtc { unicode-bidi: isolate; } :link { color: #0000EE; } :visited { color: #551A8B; } :link:active, :visited:active { color: #FF0000; } :link, :visited { text-decoration: underline; cursor: pointer; } a:link[rel~=help], a:visited[rel~=help], area:link[rel~=help], area:visited[rel~=help] { cursor: help; } :focus { outline: auto; } mark { background: yellow; color: black; } /* this color is just a suggestion and can be changed based on implementation feedback */ abbr[title], acronym[title] { text-decoration: dotted underline; } ins, u { text-decoration: underline; } del, s, strike { text-decoration: line-through; } blink { text-decoration: blink; } q::before { content: open-quote; } q::after { content: close-quote; } br { display-outside: newline; } /* this also has bidi implications */ nobr { white-space: nowrap; } wbr { display-outside: break-opportunity; } /* this also has bidi implications */ nobr wbr { white-space: normal; }
The following rules are also expected to apply, as presentational hints:
@namespace url(http://www.w3.org/1999/xhtml); br[clear=left i] { clear: left; } br[clear=right i] { clear: right; } br[clear=all i], br[clear=both i] { clear: both; }
User agents that do not support correct ruby rendering are expected to render parentheses
around the text of rt
elements in the absence of rp
elements. [CSS3-RUBY]
User agents are expected to support the clear property on inline elements (in order to render br
elements with clear
attributes) in the manner
described in the non-normative note to this effect in CSS2.1.
The initial value for the color property is expected to be black. The initial value for the background-color property is expected to be transparent. The canvas' background is expected to be white.
When a font
element has a color
attribute, its value is expected to be parsed using the rules for parsing a legacy color
value, and if that does not return an error, the user agent is expected to treat the
attribute as a presentational hint setting the
element’s color property to the resulting color.
The font
element is expected to
override the color of any text decoration that spans the text of the element to the used value of
the element’s color property.
When a font
element has a face
attribute, the user agent is expected to treat the attribute as a presentational hint setting the element’s font-family property to the attribute’s
value.
When a font
element has a size
attribute, the user agent is expected to use the following steps, known as the rules for
parsing a legacy font size, to treat the attribute as a presentational hint setting the element’s font-size property:
- Let input be the attribute’s value.
- Let position be a pointer into input, initially pointing at the start of the string.
- Skip whitespace.
- If position is past the end of input, there is no presentational hint. Abort these steps.
- If the character at position is a U+002B PLUS SIGN character (+), then let mode be relative-plus, and advance position to the next character. Otherwise, if the character at position is a U+002D HYPHEN-MINUS character (-), then let mode be relative-minus, and advance position to the next character. Otherwise, let mode be absolute.
- Collect a sequence of characters that are ASCII digits, and let the resulting sequence be digits.
- If digits is the empty string, there is no presentational hint. Abort these steps.
- Interpret digits as a base-ten integer. Let value be the resulting number.
-
If mode is relative-plus, then increment value by 3. If mode is relative-minus, then let value be the result of subtracting value from 3.
- If value is greater than 7, let it be 7.
- If value is less than 1, let it be 1.
-
Set font-size to the keyword corresponding to the value of value according to the following table:
value font-size keyword Notes 1 x-small 2 small 3 medium 4 large 5 x-large 6 xx-large 7 xxx-large see below The "xxx-large" value is a non-CSS value used here to indicate a font size 50% larger than "xx-large".
10.3.5. Bidirectional text
@namespace url(http://www.w3.org/1999/xhtml); [dir]:dir(ltr), bdi:dir(ltr), input[type=tel i]:dir(ltr) { direction: ltr; } [dir]:dir(rtl), bdi:dir(rtl) { direction: rtl; } address, blockquote, center, div, figure, figcaption, footer, form, header, hr, legend, listing, main, p, plaintext, pre, summary, xmp, article, aside, h1, h2, h3, h4, h5, h6, nav, section, table, caption, colgroup, col, thead, tbody, tfoot, tr, td, th, dir, dd, dl, dt, menu, ol, ul, li, bdi, output, [dir=ltr i], [dir=rtl i], [dir=auto i] { unicode-bidi: isolate; } bdo, bdo[dir] { unicode-bidi: isolate-override; } input[dir=auto i]:matches([type=search i], [type=tel i], [type=url i], [type=email i]), textarea[dir=auto i], pre[dir=auto i] { unicode-bidi: plaintext; } /* see prose for input elements whose type attribute is in the Text state */ /* the rules setting the 'content' property on br and wbr elements also has bidi implications */
When an input
element’s dir
attribute is in the auto state and its type
attribute is in the Text state, then the user agent is
expected to act as if it had a user-agent-level style sheet rule setting the unicode-bidi property to plaintext.
Input fields (i.e., textarea
elements, and input
elements when their type
attribute is in the Text, Search, Telephone, URL,
or E-mail state) are expected to present an editing
user interface with a directionality that matches the element’s direction property.
When the document’s character encoding is ISO-8859-8, the following rules are additionally expected to apply, following those above: [ENCODING]
@namespace url(http://www.w3.org/1999/xhtml); address, blockquote, center, div, figure, figcaption, footer, form, header, hr, legend, listing, main, p, plaintext, pre, summary, xmp, article, aside, h1, h2, h3, h4, h5, h6, nav, section, table, caption, colgroup, col, thead, tbody, tfoot, tr, td, th, dir, dd, dl, dt, menu, ol, ul, li, [dir=ltr i], [dir=rtl i], [dir=auto i], *|* { unicode-bidi: bidi-override; } input:not([type=submit i]):not([type=reset i]):not([type=button i]), textarea, keygen { unicode-bidi: normal; }
10.3.6. Quotes
This block is automatically generated from the Unicode Common Locale Data Repository. [CLDR]
User agents are expected to use either the block below (which will be regularly updated) or to
automatically generate their own copy directly from the source material. The language codes are
derived from the CLDR file names. The quotes are derived from the delimiter
blocks, with fallback handled as specified in the CLDR documentation.
@namespace url(http://www.w3.org/1999/xhtml); :root { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(af), :not(:lang(af)) > :lang(af) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(agq), :not(:lang(agq)) > :lang(agq) { quotes: '\201e' '\201d' '\201a' '\2019' } /* „ ” ‚ ’ */ :root:lang(ak), :not(:lang(ak)) > :lang(ak) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(am), :not(:lang(am)) > :lang(am) { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */ :root:lang(ar), :not(:lang(ar)) > :lang(ar) { quotes: '\201d' '\201c' '\2019' '\2018' } /* ” “ ’ ‘ */ :root:lang(asa), :not(:lang(asa)) > :lang(asa) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(az-Cyrl), :not(:lang(az-Cyrl)) > :lang(az-Cyrl) { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */ :root:lang(bas), :not(:lang(bas)) > :lang(bas) { quotes: '\00ab' '\00bb' '\201e' '\201c' } /* « » „ “ */ :root:lang(bem), :not(:lang(bem)) > :lang(bem) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(bez), :not(:lang(bez)) > :lang(bez) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(bg), :not(:lang(bg)) > :lang(bg) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(bm), :not(:lang(bm)) > :lang(bm) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(bn), :not(:lang(bn)) > :lang(bn) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(br), :not(:lang(br)) > :lang(br) { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */ :root:lang(brx), :not(:lang(brx)) > :lang(brx) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(bs-Cyrl), :not(:lang(bs-Cyrl)) > :lang(bs-Cyrl) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(ca), :not(:lang(ca)) > :lang(ca) { quotes: '\201c' '\201d' '\00ab' '\00bb' } /* “ ” « » */ :root:lang(cgg), :not(:lang(cgg)) > :lang(cgg) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(chr), :not(:lang(chr)) > :lang(chr) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(cs), :not(:lang(cs)) > :lang(cs) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(da), :not(:lang(da)) > :lang(da) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(dav), :not(:lang(dav)) > :lang(dav) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(de), :not(:lang(de)) > :lang(de) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(de-CH), :not(:lang(de-CH)) > :lang(de-CH) { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */ :root:lang(dje), :not(:lang(dje)) > :lang(dje) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(dua), :not(:lang(dua)) > :lang(dua) { quotes: '\00ab' '\00bb' '\2018' '\2019' } /* « » ‘ ’ */ :root:lang(dyo), :not(:lang(dyo)) > :lang(dyo) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(dz), :not(:lang(dz)) > :lang(dz) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ebu), :not(:lang(ebu)) > :lang(ebu) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ee), :not(:lang(ee)) > :lang(ee) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(el), :not(:lang(el)) > :lang(el) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(en), :not(:lang(en)) > :lang(en) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(es), :not(:lang(es)) > :lang(es) { quotes: '\201c' '\201d' '\00ab' '\00bb' } /* “ ” « » */ :root:lang(et), :not(:lang(et)) > :lang(et) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(eu), :not(:lang(eu)) > :lang(eu) { quotes: '\201c' '\201d' '\00ab' '\00bb' } /* “ ” « » */ :root:lang(ewo), :not(:lang(ewo)) > :lang(ewo) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(fa), :not(:lang(fa)) > :lang(fa) { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */ :root:lang(ff), :not(:lang(ff)) > :lang(ff) { quotes: '\201e' '\201d' '\201a' '\2019' } /* „ ” ‚ ’ */ :root:lang(fi), :not(:lang(fi)) > :lang(fi) { quotes: '\201d' '\201d' '\2019' '\2019' } /* ” ” ’ ’ */ :root:lang(fr), :not(:lang(fr)) > :lang(fr) { quotes: '\00ab' '\00bb' '\00ab' '\00bb' } /* « » « » */ :root:lang(fr-CA), :not(:lang(fr-CA)) > :lang(fr-CA) { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */ :root:lang(fr-CH), :not(:lang(fr-CH)) > :lang(fr-CH) { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */ :root:lang(gsw), :not(:lang(gsw)) > :lang(gsw) { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */ :root:lang(gu), :not(:lang(gu)) > :lang(gu) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(guz), :not(:lang(guz)) > :lang(guz) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ha), :not(:lang(ha)) > :lang(ha) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(he), :not(:lang(he)) > :lang(he) { quotes: '\0022' '\0022' '\0027' '\0027' } /* " " ' ' */ :root:lang(hi), :not(:lang(hi)) > :lang(hi) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(hr), :not(:lang(hr)) > :lang(hr) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(hu), :not(:lang(hu)) > :lang(hu) { quotes: '\201e' '\201d' '\00bb' '\00ab' } /* „ ” » « */ :root:lang(id), :not(:lang(id)) > :lang(id) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ig), :not(:lang(ig)) > :lang(ig) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(it), :not(:lang(it)) > :lang(it) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(ja), :not(:lang(ja)) > :lang(ja) { quotes: '\300c' '\300d' '\300e' '\300f' } /* 「 」 『 』 */ :root:lang(jgo), :not(:lang(jgo)) > :lang(jgo) { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */ :root:lang(jmc), :not(:lang(jmc)) > :lang(jmc) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(kab), :not(:lang(kab)) > :lang(kab) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(kam), :not(:lang(kam)) > :lang(kam) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(kde), :not(:lang(kde)) > :lang(kde) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(kea), :not(:lang(kea)) > :lang(kea) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(khq), :not(:lang(khq)) > :lang(khq) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ki), :not(:lang(ki)) > :lang(ki) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(kkj), :not(:lang(kkj)) > :lang(kkj) { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */ :root:lang(kln), :not(:lang(kln)) > :lang(kln) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(km), :not(:lang(km)) > :lang(km) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(kn), :not(:lang(kn)) > :lang(kn) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ko), :not(:lang(ko)) > :lang(ko) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ksb), :not(:lang(ksb)) > :lang(ksb) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ksf), :not(:lang(ksf)) > :lang(ksf) { quotes: '\00ab' '\00bb' '\2018' '\2019' } /* « » ‘ ’ */ :root:lang(lag), :not(:lang(lag)) > :lang(lag) { quotes: '\201d' '\201d' '\2019' '\2019' } /* ” ” ’ ’ */ :root:lang(lg), :not(:lang(lg)) > :lang(lg) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ln), :not(:lang(ln)) > :lang(ln) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(lo), :not(:lang(lo)) > :lang(lo) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(lt), :not(:lang(lt)) > :lang(lt) { quotes: '\201e' '\201c' '\201e' '\201c' } /* „ “ „ “ */ :root:lang(lu), :not(:lang(lu)) > :lang(lu) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(luo), :not(:lang(luo)) > :lang(luo) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(luy), :not(:lang(luy)) > :lang(luy) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(lv), :not(:lang(lv)) > :lang(lv) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(mas), :not(:lang(mas)) > :lang(mas) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(mer), :not(:lang(mer)) > :lang(mer) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(mfe), :not(:lang(mfe)) > :lang(mfe) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(mg), :not(:lang(mg)) > :lang(mg) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(mgo), :not(:lang(mgo)) > :lang(mgo) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(mk), :not(:lang(mk)) > :lang(mk) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(ml), :not(:lang(ml)) > :lang(ml) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(mr), :not(:lang(mr)) > :lang(mr) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ms), :not(:lang(ms)) > :lang(ms) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(mua), :not(:lang(mua)) > :lang(mua) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(my), :not(:lang(my)) > :lang(my) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(naq), :not(:lang(naq)) > :lang(naq) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(nb), :not(:lang(nb)) > :lang(nb) { quotes: '\00ab' '\00bb' '\2018' '\2019' } /* « » ‘ ’ */ :root:lang(nd), :not(:lang(nd)) > :lang(nd) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(nl), :not(:lang(nl)) > :lang(nl) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(nmg), :not(:lang(nmg)) > :lang(nmg) { quotes: '\201e' '\201d' '\00ab' '\00bb' } /* „ ” « » */ :root:lang(nn), :not(:lang(nn)) > :lang(nn) { quotes: '\00ab' '\00bb' '\2018' '\2019' } /* « » ‘ ’ */ :root:lang(nnh), :not(:lang(nnh)) > :lang(nnh) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(nus), :not(:lang(nus)) > :lang(nus) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(nyn), :not(:lang(nyn)) > :lang(nyn) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(pl), :not(:lang(pl)) > :lang(pl) { quotes: '\201e' '\201d' '\00ab' '\00bb' } /* „ ” « » */ :root:lang(pt), :not(:lang(pt)) > :lang(pt) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(pt-PT), :not(:lang(pt-PT)) > :lang(pt-PT) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(rn), :not(:lang(rn)) > :lang(rn) { quotes: '\201d' '\201d' '\2019' '\2019' } /* ” ” ’ ’ */ :root:lang(ro), :not(:lang(ro)) > :lang(ro) { quotes: '\201e' '\201d' '\00ab' '\00bb' } /* „ ” « » */ :root:lang(rof), :not(:lang(rof)) > :lang(rof) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ru), :not(:lang(ru)) > :lang(ru) { quotes: '\00ab' '\00bb' '\201e' '\201c' } /* « » „ “ */ :root:lang(rw), :not(:lang(rw)) > :lang(rw) { quotes: '\00ab' '\00bb' '\2018' '\2019' } /* « » ‘ ’ */ :root:lang(rwk), :not(:lang(rwk)) > :lang(rwk) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(saq), :not(:lang(saq)) > :lang(saq) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(sbp), :not(:lang(sbp)) > :lang(sbp) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(seh), :not(:lang(seh)) > :lang(seh) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ses), :not(:lang(ses)) > :lang(ses) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(sg), :not(:lang(sg)) > :lang(sg) { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */ :root:lang(shi), :not(:lang(shi)) > :lang(shi) { quotes: '\00ab' '\00bb' '\201e' '\201d' } /* « » „ ” */ :root:lang(shi-Latn), :not(:lang(shi-Latn)) > :lang(shi-Latn) { quotes: '\00ab' '\00bb' '\201e' '\201d' } /* « » „ ” */ :root:lang(si), :not(:lang(si)) > :lang(si) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(sk), :not(:lang(sk)) > :lang(sk) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(sl), :not(:lang(sl)) > :lang(sl) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(sn), :not(:lang(sn)) > :lang(sn) { quotes: '\201d' '\201d' '\2019' '\2019' } /* ” ” ’ ’ */ :root:lang(so), :not(:lang(so)) > :lang(so) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(sq), :not(:lang(sq)) > :lang(sq) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(sr), :not(:lang(sr)) > :lang(sr) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(sr-Latn), :not(:lang(sr-Latn)) > :lang(sr-Latn) { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */ :root:lang(sv), :not(:lang(sv)) > :lang(sv) { quotes: '\201d' '\201d' '\2019' '\2019' } /* ” ” ’ ’ */ :root:lang(sw), :not(:lang(sw)) > :lang(sw) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(swc), :not(:lang(swc)) > :lang(swc) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ta), :not(:lang(ta)) > :lang(ta) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(te), :not(:lang(te)) > :lang(te) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(teo), :not(:lang(teo)) > :lang(teo) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(th), :not(:lang(th)) > :lang(th) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(ti-ER), :not(:lang(ti-ER)) > :lang(ti-ER) { quotes: '\2018' '\2019' '\201c' '\201d' } /* ‘ ’ “ ” */ :root:lang(to), :not(:lang(to)) > :lang(to) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(tr), :not(:lang(tr)) > :lang(tr) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(twq), :not(:lang(twq)) > :lang(twq) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(tzm), :not(:lang(tzm)) > :lang(tzm) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(uk), :not(:lang(uk)) > :lang(uk) { quotes: '\00ab' '\00bb' '\201e' '\201c' } /* « » „ “ */ :root:lang(ur), :not(:lang(ur)) > :lang(ur) { quotes: '\201d' '\201c' '\2019' '\2018' } /* ” “ ’ ‘ */ :root:lang(vai), :not(:lang(vai)) > :lang(vai) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(vai-Latn), :not(:lang(vai-Latn)) > :lang(vai-Latn) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(vi), :not(:lang(vi)) > :lang(vi) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(vun), :not(:lang(vun)) > :lang(vun) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(xh), :not(:lang(xh)) > :lang(xh) { quotes: '\2018' '\2019' '\201c' '\201d' } /* ‘ ’ “ ” */ :root:lang(xog), :not(:lang(xog)) > :lang(xog) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(yav), :not(:lang(yav)) > :lang(yav) { quotes: '\00ab' '\00bb' '\00ab' '\00bb' } /* « » « » */ :root:lang(yo), :not(:lang(yo)) > :lang(yo) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(zh), :not(:lang(zh)) > :lang(zh) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */ :root:lang(zh-Hant), :not(:lang(zh-Hant)) > :lang(zh-Hant) { quotes: '\300c' '\300d' '\300e' '\300f' } /* 「 」 『 』 */ :root:lang(zu), :not(:lang(zu)) > :lang(zu) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
10.3.7. Sections and headings
@namespace url(http://www.w3.org/1999/xhtml); article, aside, h1, h2, h3, h4, h5, h6, nav, section { display: block; } h1 { margin-top: 0.67em; margin-bottom: 0.67em; font-size: 2.00em; font-weight: bold; } h2 { margin-top: 0.83em; margin-bottom: 0.83em; font-size: 1.50em; font-weight: bold; } h3 { margin-top: 1.00em; margin-bottom: 1.00em; font-size: 1.17em; font-weight: bold; } h4 { margin-top: 1.33em; margin-bottom: 1.33em; font-size: 1.00em; font-weight: bold; } h5 { margin-top: 1.67em; margin-bottom: 1.67em; font-size: 0.83em; font-weight: bold; } h6 { margin-top: 2.33em; margin-bottom: 2.33em; font-size: 0.67em; font-weight: bold; }
In the following CSS block, x is shorthand for the following selector: :matches(article, aside, nav, section)
@namespace url(http://www.w3.org/1999/xhtml); x h1 { margin-top: 0.83em; margin-bottom: 0.83em; font-size: 1.50em; } x x h1 { margin-top: 1.00em; margin-bottom: 1.00em; font-size: 1.17em; } x x x h1 { margin-top: 1.33em; margin-bottom: 1.33em; font-size: 1.00em; } x x x x h1 { margin-top: 1.67em; margin-bottom: 1.67em; font-size: 0.83em; } x x x x x h1 { margin-top: 2.33em; margin-bottom: 2.33em; font-size: 0.67em; }
The shorthand is used to keep this block at least mildly readable.
10.3.8. Lists
@namespace url(http://www.w3.org/1999/xhtml); dir, dd, dl, dt, menu, ol, ul { display: block; } li { display: list-item; } dir, dl, menu, ol, ul { margin-top: 1em; margin-bottom: 1em; } :matches(dir, dl, menu, ol, ul) :matches(dir, dl, menu, ol, ul) { margin-top: 0; margin-bottom: 0; } dd { margin-left: 40px; } /* LTR-specific: use 'margin-right' for rtl elements */ dir, menu, ol, ul { padding-left: 40px; } /* LTR-specific: use 'padding-right' for rtl elements */ ol { list-style-type: decimal; } dir, menu, ul { list-style-type: disc; } :matches(dir, menu, ol, ul) :matches(dir, menu, ul) { list-style-type: circle; } :matches(dir, menu, ol, ul) :matches(dir, menu, ol, ul) :matches(dir, menu, ul) { list-style-type: square; }
The following rules are also expected to apply, as presentational hints:
@namespace url(http://www.w3.org/1999/xhtml); ol[type=1], li[type=1] { list-style-type: decimal; } ol[type=a], li[type=a] { list-style-type: lower-alpha; } ol[type=A], li[type=A] { list-style-type: upper-alpha; } ol[type=i], li[type=i] { list-style-type: lower-roman; } ol[type=I], li[type=I] { list-style-type: upper-roman; } ul[type=none i], li[type=none i] { list-style-type: none; } ul[type=disc i], li[type=disc i] { list-style-type: disc; } ul[type=circle i], li[type=circle i] { list-style-type: circle; } ul[type=square i], li[type=square i] { list-style-type: square; }
In the above stylesheet, the attribute selectors for the ol
and li
elements are expected to be treated as case-sensitive.
When rendering li
elements, non-CSS user agents are expected to use the ordinal value of the li
element to render the counter in the list item
marker.
This specification does not yet define the
CSS-specific rules for rendering li
elements, because CSS doesn’t yet provide
sufficient hooks for this purpose.
10.3.9. Tables
@namespace url(http://www.w3.org/1999/xhtml); table { display: table; } caption { display: table-caption; } colgroup, colgroup[hidden] { display: table-column-group; } col, col[hidden] { display: table-column; } thead, thead[hidden] { display: table-header-group; } tbody, tbody[hidden] { display: table-row-group; } tfoot, tfoot[hidden] { display: table-footer-group; } tr, tr[hidden] { display: table-row; } td, th, td[hidden], th[hidden] { display: table-cell; } colgroup[hidden], col[hidden], thead[hidden], tbody[hidden], tfoot[hidden], tr[hidden], td[hidden], th[hidden] { visibility: collapse; } table { box-sizing: border-box; border-spacing: 2px; border-collapse: separate; text-indent: initial; } td, th { padding: 1px; } th { font-weight: bold; } thead, tbody, tfoot, table > tr { vertical-align: middle; } tr, td, th { vertical-align: inherit; } table, td, th { border-color: gray; } thead, tbody, tfoot, tr { border-color: inherit; } table[rules=none i], table[rules=groups i], table[rules=rows i], table[rules=cols i], table[rules=all i], table[frame=void i], table[frame=above i], table[frame=below i], table[frame=hsides i], table[frame=lhs i], table[frame=rhs i], table[frame=vsides i], table[frame=box i], table[frame=border i], table[rules=none i] > tr > td, table[rules=none i] > tr > th, table[rules=groups i] > tr > td, table[rules=groups i] > tr > th, table[rules=rows i] > tr > td, table[rules=rows i] > tr > th, table[rules=cols i] > tr > td, table[rules=cols i] > tr > th, table[rules=all i] > tr > td, table[rules=all i] > tr > th, table[rules=none i] > thead > tr > td, table[rules=none i] > thead > tr > th, table[rules=groups i] > thead > tr > td, table[rules=groups i] > thead > tr > th, table[rules=rows i] > thead > tr > td, table[rules=rows i] > thead > tr > th, table[rules=cols i] > thead > tr > td, table[rules=cols i] > thead > tr > th, table[rules=all i] > thead > tr > td, table[rules=all i] > thead > tr > th, table[rules=none i] > tbody > tr > td, table[rules=none i] > tbody > tr > th, table[rules=groups i] > tbody > tr > td, table[rules=groups i] > tbody > tr > th, table[rules=rows i] > tbody > tr > td, table[rules=rows i] > tbody > tr > th, table[rules=cols i] > tbody > tr > td, table[rules=cols i] > tbody > tr > th, table[rules=all i] > tbody > tr > td, table[rules=all i] > tbody > tr > th, table[rules=none i] > tfoot > tr > td, table[rules=none i] > tfoot > tr > th, table[rules=groups i] > tfoot > tr > td, table[rules=groups i] > tfoot > tr > th, table[rules=rows i] > tfoot > tr > td, table[rules=rows i] > tfoot > tr > th, table[rules=cols i] > tfoot > tr > td, table[rules=cols i] > tfoot > tr > th, table[rules=all i] > tfoot > tr > td, table[rules=all i] > tfoot > tr > th { border-color: black; }
The following rules are also expected to apply, as presentational hints:
@namespace url(http://www.w3.org/1999/xhtml); table[align=left i] { float: left; } table[align=right i] { float: right; } table[align=center i] { margin-left: auto; margin-right: auto; } thead[align=absmiddle i], tbody[align=absmiddle i], tfoot[align=absmiddle i], tr[align=absmiddle i], td[align=absmiddle i], th[align=absmiddle i] { text-align: center; } caption[align=bottom i] { caption-side: bottom; } p[align=left i], h1[align=left i], h2[align=left i], h3[align=left i], h4[align=left i], h5[align=left i], h6[align=left i] { text-align: left; } p[align=right i], h1[align=right i], h2[align=right i], h3[align=right i], h4[align=right i], h5[align=right i], h6[align=right i] { text-align: right; } p[align=center i], h1[align=center i], h2[align=center i], h3[align=center i], h4[align=center i], h5[align=center i], h6[align=center i] { text-align: center; } p[align=justify i], h1[align=justify i], h2[align=justify i], h3[align=justify i], h4[align=justify i], h5[align=justify i], h6[align=justify i] { text-align: justify; } thead[valign=top i], tbody[valign=top i], tfoot[valign=top i], tr[valign=top i], td[valign=top i], th[valign=top i] { vertical-align: top; } thead[valign=middle i], tbody[valign=middle i], tfoot[valign=middle i], tr[valign=middle i], td[valign=middle i], th[valign=middle i] { vertical-align: middle; } thead[valign=bottom i], tbody[valign=bottom i], tfoot[valign=bottom i], tr[valign=bottom i], td[valign=bottom i], th[valign=bottom i] { vertical-align: bottom; } thead[valign=baseline i], tbody[valign=baseline i], tfoot[valign=baseline i], tr[valign=baseline i], td[valign=baseline i], th[valign=baseline i] { vertical-align: baseline; } td[nowrap], th[nowrap] { white-space: nowrap; } table[rules=none i], table[rules=groups i], table[rules=rows i], table[rules=cols i], table[rules=all i] { border-style: hidden; border-collapse: collapse; } table[border] { border-style: outset; } /* only if border is not equivalent to zero */ table[frame=void i] { border-style: hidden; } table[frame=above i] { border-style: outset hidden hidden hidden; } table[frame=below i] { border-style: hidden hidden outset hidden; } table[frame=hsides i] { border-style: outset hidden outset hidden; } table[frame=lhs i] { border-style: hidden hidden hidden outset; } table[frame=rhs i] { border-style: hidden outset hidden hidden; } table[frame=vsides i] { border-style: hidden outset; } table[frame=box i], table[frame=border i] { border-style: outset; } table[border] > tr > td, table[border] > tr > th, table[border] > thead > tr > td, table[border] > thead > tr > th, table[border] > tbody > tr > td, table[border] > tbody > tr > th, table[border] > tfoot > tr > td, table[border] > tfoot > tr > th { /* only if border is not equivalent to zero */ border-width: 1px; border-style: inset; } table[rules=none i] > tr > td, table[rules=none i] > tr > th, table[rules=none i] > thead > tr > td, table[rules=none i] > thead > tr > th, table[rules=none i] > tbody > tr > td, table[rules=none i] > tbody > tr > th, table[rules=none i] > tfoot > tr > td, table[rules=none i] > tfoot > tr > th, table[rules=groups i] > tr > td, table[rules=groups i] > tr > th, table[rules=groups i] > thead > tr > td, table[rules=groups i] > thead > tr > th, table[rules=groups i] > tbody > tr > td, table[rules=groups i] > tbody > tr > th, table[rules=groups i] > tfoot > tr > td, table[rules=groups i] > tfoot > tr > th, table[rules=rows i] > tr > td, table[rules=rows i] > tr > th, table[rules=rows i] > thead > tr > td, table[rules=rows i] > thead > tr > th, table[rules=rows i] > tbody > tr > td, table[rules=rows i] > tbody > tr > th, table[rules=rows i] > tfoot > tr > td, table[rules=rows i] > tfoot > tr > th { border-width: 1px; border-style: none; } table[rules=cols i] > tr > td, table[rules=cols i] > tr > th, table[rules=cols i] > thead > tr > td, table[rules=cols i] > thead > tr > th, table[rules=cols i] > tbody > tr > td, table[rules=cols i] > tbody > tr > th, table[rules=cols i] > tfoot > tr > td, table[rules=cols i] > tfoot > tr > th { border-width: 1px; border-style: none solid; } table[rules=all i] > tr > td, table[rules=all i] > tr > th, table[rules=all i] > thead > tr > td, table[rules=all i] > thead > tr > th, table[rules=all i] > tbody > tr > td, table[rules=all i] > tbody > tr > th, table[rules=all i] > tfoot > tr > td, table[rules=all i] > tfoot > tr > th { border-width: 1px; border-style: solid; } table[rules=groups i] > colgroup { border-left-width: 1px; border-left-style: solid; border-right-width: 1px; border-right-style: solid; } table[rules=groups i] > thead, table[rules=groups i] > tbody, table[rules=groups i] > tfoot { border-top-width: 1px; border-top-style: solid; border-bottom-width: 1px; border-bottom-style: solid; } table[rules=rows i] > tr, table[rules=rows i] > thead > tr, table[rules=rows i] > tbody > tr, table[rules=rows i] > tfoot > tr { border-top-width: 1px; border-top-style: solid; border-bottom-width: 1px; border-bottom-style: solid; }
In quirks mode, the following rules are also expected to apply:
@namespace url(http://www.w3.org/1999/xhtml); table { font-weight: initial; font-style: initial; font-variant: initial; font-size: initial; line-height: initial; white-space: initial; text-align: initial; }
For the purposes of the CSS table model, the col
element is expected to be treated
as if it was present as many times as its span
attribute specifies.
For the purposes of the CSS table model, the colgroup
element, if it contains no col
element, is expected to be treated as if it had as many such children as its span
attribute specifies.
For the purposes of the CSS table model, the colspan
and rowspan
attributes on td
and th
elements are expected to provide the special knowledge regarding cells spanning rows and columns.
In HTML documents, the following rules are also expected to apply:
@namespace url(http://www.w3.org/1999/xhtml); :matches(table, thead, tbody, tfoot, tr) > form { display: none !important; }
The table
element’s cellspacing
attribute maps to the pixel length property border-spacing on the element.
The table
element’s cellpadding
attribute maps to the pixel length
properties padding-top, padding-right, padding-bottom, and padding-left of any td
and th
elements that have corresponding cells in the table corresponding to
the table
element.
The table
element’s hspace
attribute maps to the dimension properties margin-left and margin-right on the table
element.
The table
element’s vspace
attribute maps to the dimension properties margin-top and margin-bottom on the table
element.
The table
element’s height
attribute maps to the dimension property (ignoring zero) height on the table
element.
The table
element’s width
attribute maps to the dimension property (ignoring zero) width on the table
element.
The col
element’s width
attribute maps
to the dimension property (ignoring zero) width on the col
element.
The tr
element’s height
attribute maps
to the dimension property (ignoring zero) height on the tr
element.
The td
and th
elements' height
attributes map to the dimension
property (ignoring zero) height on the element.
The td
and th
elements' width
attributes map to the dimension
property (ignoring zero) width on the element.
The caption
element unless specified otherwise below, and the thead
, tbody
, tfoot
, tr
, td
, and th
elements when they have an align
attribute whose value is an ASCII
case-insensitive match for either the string "center
" or the string
"middle
", are expected to center text within themselves, as if they had
their text-align property set to center in a presentational hint, and to align descendants to the center.
The caption
, thead
, tbody
, tfoot
, tr
, td
, and th
elements, when they have an align
attribute whose value is an ASCII case-insensitive match for
the string "left
", are expected to left-align text within themselves, as if
they had their text-align property set to left in a presentational hint, and to align descendants to the left.
The caption
, thead
, tbody
, tfoot
, tr
, td
, and th
elements, when they have an align
attribute whose value is an ASCII case-insensitive match for
the string "right
", are expected to right-align text within themselves, as
if they had their text-align property set to right in a presentational hint, and to align descendants to the right.
The caption
, thead
, tbody
, tfoot
, tr
, td
, and th
elements, when they have an align
attribute whose value is an ASCII case-insensitive match for
the string "justify
", are expected to full-justify text within themselves,
as if they had their text-align property set to justify in a presentational hint, and to align descendants to the left.
User agents are expected to have a rule in their user agent stylesheet that matches th
elements that have a parent node whose computed value for the text-align property is its initial value, whose declaration block consists of just a single declaration that
sets the text-align property to the value center.
When a table
, thead
, tbody
, tfoot
, tr
, td
, or th
element has a background
attribute set to a non-empty value, the new value is
expected to be parsed relative to the element’s node document, and if this is
successful, the user agent is expected to treat the attribute as a presentational hint setting the element’s background-image property to the resulting URL string.
When a table
, thead
, tbody
, tfoot
, tr
, td
, or th
element has a bgcolor
attribute set, the new value is expected to be parsed using the rules for parsing a legacy
color value, and if that does not return an error, the user agent is expected to treat the
attribute as a presentational hint setting the element’s background-color property to the resulting color.
When a table
element has a bordercolor
attribute, its value is expected to be parsed using the rules for parsing a legacy color
value, and if that does not return an error, the user agent is expected to treat the
attribute as a presentational hint setting the element’s border-top-color, border-right-color, border-bottom-color, and border-left-color properties to the resulting color.
The table
element’s border
attribute maps to the pixel length properties border-top-width, border-right-width, border-bottom-width, border-left-width on the
element. If the attribute is present but parsing the attribute’s value using the rules for
parsing non-negative integers generates an error, a default value of 1px is expected to be
used for that property instead.
Rules marked "only if border is not equivalent to zero"
in the CSS block above is expected to only be applied if the border
attribute mentioned in the selectors for the rule is not
only present but, when parsed using the rules for parsing non-negative integers, is
also found to have a value other than zero or to generate an error.
In quirks mode, a td
element or a th
element that has a nowrap
attribute but also has a width
attribute whose value, when parsed using the rules for
parsing non-zero dimension values, is found to be a length (not an error or a number
classified as a percentage), is expected to have a presentational hint setting the element’s white-space property to normal,
overriding the rule in the CSS block above that sets it to nowrap.
10.3.10. Margin collapsing quirks
A node is substantial if it is a text node that is not inter-element whitespace, or if it is an element node.
A node is blank if it is an element that contains no substantial nodes.
The elements with default margins are the following elements: blockquote
, dir
, dl
, h1
, h2
, h3
, h4
, h5
, h6
, listing
, menu
, ol
, p
, plaintext
, pre
, ul
, xmp
In quirks mode, any element with default margins that is the child of a body
, td
, or th
element and has no substantial previous siblings is expected to have a user-agent level style sheet rule that sets its margin-top property to zero.
In quirks mode, any element
with default margins that is the child of a body
, td
, or th
element, has no substantial previous siblings, and is blank, is expected to have
a user-agent level style sheet rule that sets its margin-bottom property to zero also.
In quirks mode, any element
with default margins that is the child of a td
or th
element, has
no substantial following siblings, and is blank, is expected to have a user-agent level style sheet
rule that sets its margin-top property to zero.
In quirks mode, any p
element that is the child of a td
or th
element and has no substantial following siblings, is expected to have a
user-agent level style sheet rule that sets its margin-bottom property to zero.
10.3.11. Form controls
@namespace url(http://www.w3.org/1999/xhtml); input, select, option, optgroup, button, textarea, keygen { text-indent: initial; } input:matches([type=radio i], [type=checkbox i], [type=reset i], [type=button i], [type=submit i], [type=search i]), select, button { box-sizing: border-box; }
In quirks mode, the following rules are also expected to apply:
@namespace url(http://www.w3.org/1999/xhtml); input:not([type=image i]), textarea { box-sizing: border-box; }
Each kind of form control is also given a specific default binding, as described in subsequent sections, which implements the look and feel of the control.
10.3.12. The hr
element
@namespace url(http://www.w3.org/1999/xhtml); hr { color: gray; border-style: inset; border-width: 1px; margin: 0.5em auto; }
The following rules are also expected to apply, as presentational hints:
@namespace url(http://www.w3.org/1999/xhtml); hr[align=left] { margin-left: 0; margin-right: auto; } hr[align=right] { margin-left: auto; margin-right: 0; } hr[align=center] { margin-left: auto; margin-right: auto; } hr[color], hr[noshade] { border-style: solid; }
If an hr
element has either a color
attribute
or a noshade
attribute, and furthermore also has a size
attribute, and parsing that attribute’s value using the rules for parsing non-negative integers doesn’t generate an error, then the user
agent is expected to use the parsed value divided by two as a pixel length for presentational hints for the properties border-top-width, border-right-width, border-bottom-width, and border-left-width on the element.
Otherwise, if an hr
element has neither a color
attribute nor a noshade
attribute, but does have a size
attribute, and parsing that attribute’s value using the rules for parsing non-negative integers doesn’t generate an error, then: if the
parsed value is one, then the user agent is expected to use the attribute as a presentational hint setting the element’s border-bottom-width to 0; otherwise, if the parsed value is greater than one, then the user
agent is expected to use the parsed value minus two as a pixel length for presentational
hints for the height property on the element.
The width
attribute on an hr
element maps
to the dimension property width on the element.
When an hr
element has a color
attribute, its
value is expected to be parsed using the rules for parsing a legacy color value, and
if that does not return an error, the user agent is expected to treat the attribute as a presentational hint setting the element’s color property to
the resulting color.
10.3.13. The fieldset
and legend
elements
@namespace url(http://www.w3.org/1999/xhtml); fieldset { display: block; margin-left: 2px; margin-right: 2px; border: groove 2px ThreeDFace; padding: 0.35em 0.625em 0.75em; min-width: min-content; } legend { padding-left: 2px; padding-right: 2px; }
The fieldset
element is expected to establish a new block formatting context.
If the fieldset
element has a child that matches the conditions in the list below,
then the first such child is the fieldset
element’s rendered legend:
- The child is a
legend
element. - The child is not out-of-flow (e.g., not absolutely positioned or floated).
- The child is generating a box (e.g., it is not 'display:none').
A fieldset
element’s rendered legend, if any, is expected to be
rendered over the top border edge of the fieldset
element as a block box
(overriding any explicit display value). In the absence of an explicit width, the box should
shrink-wrap. If the legend
element in question has an align
attribute, and its value is an ASCII
case-insensitive match for one of the strings in the first column of the following table,
then the legend
is expected to be rendered horizontally aligned over the border edge
in the position given in the corresponding cell on the same row in the second column. If the
attribute is absent or has a value that doesn’t match any of the cases in the table, then the
position is expected to be on the right if the direction property on this element has a computed
value of rtl, and on the left otherwise.
Attribute value | Alignment position |
---|---|
left
| On the left |
right
| On the right |
center
| In the middle |
10.4. Replaced elements
10.4.1. Embedded content
The embed
, iframe
, and video
elements are expected to be
treated as replaced elements.
A canvas
element that represents embedded content is
expected to be treated as a replaced element; the contents of such elements are the
element’s bitmap, if any, or else a transparent black bitmap with the same intrinsic
dimensions as the element. Other canvas
elements are expected to be treated
as ordinary elements in the rendering model.
An object
element that represents an image, plugin, or nested browsing context is expected to be treated as a replaced element. Other object
elements are expected to be treated as ordinary elements in the rendering
model.
An applet
element that represents a plugin is expected
to be treated as a replaced element. Other applet
elements are expected
to be treated as ordinary elements in the rendering model.
The audio
element, when it is exposing a user interface, is expected to be treated as a replaced element about one line high, as wide as is necessary to expose the user
agent’s user interface features. When an audio
element is not exposing a user interface, the user agent is expected to force
its display property to compute to none, irrespective of CSS rules.
Whether a video
element is exposing a user interface is not expected to affect the size of the rendering;
controls are expected to be overlaid above the page content without causing any layout changes,
and are expected to disappear when the user does not need them.
When a video
element represents a poster frame or frame of video, the poster frame
or frame of video is expected to be rendered at the largest size that maintains the aspect ratio
of that poster frame or frame of video without being taller or wider than the video
element itself, and is expected to be centered in the video
element.
Any subtitles or captions are expected to be overlayed directly on top of their video
element, as defined by the relevant rendering rules; for WebVTT, those are the rules for updating the display of WebVTT text tracks. [WEBVTT]
When the user agent starts exposing a user
interface for a video
element, the user agent should run the rules for
updating the text track rendering of each of the text
tracks in the video
element’s list of text tracks that are showing and whose text track kind is one of subtitles
or captions
(e.g., for text
tracks based on WebVTT, the rules for updating the display of WebVTT
text tracks). [WEBVTT]
Resizing video
and canvas
elements does not interrupt
video playback or clear the canvas.
The following CSS rules are expected to apply:
@namespace url(http://www.w3.org/1999/xhtml); video { object-fit: contain; }
10.4.2. Images
User agents are expected to render img
elements and input
elements
whose type
attributes are in the image button state, according to the first applicable rules
from the following list:
- If the element represents an image
- The user agent is expected to treat the element as a replaced element and render the image according to the rules for doing so defined in CSS.
-
If the element does not represent an image, but the element already has intrinsic dimensions (e.g., from the dimension attributes or CSS rules), and either:
- the user agent has reason to believe that the image will become available and be rendered in due course, or
- the element has no
alt
attribute, or - the
Document
is in quirks mode
- The user agent is expected to treat the element as a replaced element whose
content is the text that the element represents, if any, optionally alongside an icon indicating
that the image is being obtained (if applicable). For
input
elements, the element is expected to appear button-like to indicate that the element is a button. - If the element is an
img
element that represents some text and the user agent does not expect this to change - The user agent is expected to treat the element as a non-replaced phrasing element whose content is the text, optionally with an icon indicating that an image is missing, so that the user can request the image be displayed or investigate why it is not rendering. In non-graphical contexts, such an icon should be omitted.
- If the element is an
img
element that represents nothing and the user agent does not expect this to change - The user agent is expected to treat the element as an empty inline element. (In the absence of further styles, this will cause the element to essentially not be rendered.)
- If the element is an
input
element that does not represent an image and the user agent does not expect this to change - The user agent is expected to treat the element as a replaced element consisting of a button whose content is the element’s alternative text. The intrinsic dimensions of the button are expected to be about one line in height and whatever width is necessary to render the text on one line.
The icons mentioned above are expected to be relatively small so as not to disrupt most text but be easily clickable. In a visual environment, for instance, icons could be 16 pixels by 16 pixels square, or 1em by 1em if the images are scalable. In an audio environment, the icon could be a short bleep. The icons are intended to indicate to the user that they can be used to get to whatever options the user agent provides for images, and, where appropriate, are expected to provide access to the context menu that would have come up if the user interacted with the actual image.
All animated images with the same absolute URL and the same image data are expected to be rendered synchronized to the same timeline as a group, with the timeline starting at the time of the least recent addition to the group.
In other words, when a second image with the same absolute URL and animated image data is inserted into a document, it jumps to the point in the animation cycle that is currently being displayed by the first image.
When a user agent is to restart the animation for an img
element
showing an animated image, all animated images with the same absolute URL and the
same image data in that img
element’s node document are expected to restart
their animation from the beginning.
The following CSS rules are expected to apply when the Document
is in quirks
mode:
@namespace url(http://www.w3.org/1999/xhtml); img[align=left i] { margin-right: 3px; } img[align=right i] { margin-left: 3px; }
10.4.3. Attributes for embedded content and images
The following CSS rules are expected to apply as presentational hints:
@namespace url(http://www.w3.org/1999/xhtml); iframe[frameborder=0], iframe[frameborder=no i] { border: none; } applet[align=left i], embed[align=left i], iframe[align=left i], img[align=left i], input[type=image i][align=left i], object[align=left i] { float: left; } applet[align=right i], embed[align=right i], iframe[align=right i], img[align=right i], input[type=image i][align=right i], object[align=right i] { float: right; } applet[align=top i], embed[align=top i], iframe[align=top i], img[align=top i], input[type=image i][align=top i], object[align=top i] { vertical-align: top; } applet[align=baseline i], embed[align=baseline i], iframe[align=baseline i], img[align=baseline i], input[type=image i][align=baseline i], object[align=baseline i] { vertical-align: baseline; } applet[align=texttop i], embed[align=texttop i], iframe[align=texttop i], img[align=texttop i], input[type=image i][align=texttop i], object[align=texttop i] { vertical-align: text-top; } applet[align=absmiddle i], embed[align=absmiddle i], iframe[align=absmiddle i], img[align=absmiddle i], input[type=image i][align=absmiddle i], object[align=absmiddle i], applet[align=abscenter i], embed[align=abscenter i], iframe[align=abscenter i], img[align=abscenter i], input[type=image i][align=abscenter i], object[align=abscenter i] { vertical-align: middle; } applet[align=bottom i], embed[align=bottom i], iframe[align=bottom i], img[align=bottom i], input[type=image i][align=bottom i], object[align=bottom i] { vertical-align: bottom; }
When an applet
, embed
, iframe
, img
, or object
element, or an input
element whose type
attribute is in the image button state, has an align
attribute whose value is an ASCII case-insensitive match for the string "center
" or the string "middle
", the user agent is expected
to act as if the element’s vertical-align property was set to a value that aligns the vertical
middle of the element with the parent element’s baseline.
The hspace
attribute of applet
, embed
, iframe
, img
, or object
elements, and input
elements with a type
attribute in the image button state, maps to the dimension properties margin-left and margin-right on the
element.
The vspace
attribute of applet
, embed
, iframe
, img
, or object
elements, and input
elements with a type
attribute in the image button state, maps to the dimension properties margin-top and margin-bottom on the
element.
When an img
element, object
element, or input
element
with a type
attribute in the image button state has a border
attribute whose value, when parsed using the rules for
parsing non-negative integers, is found to be a number greater than zero, the user agent is
expected to use the parsed value for eight presentational hints: four setting the
parsed value as a pixel length for the element’s border-top-width, border-right-width, border-bottom-width, and border-left-width properties, and four setting the element’s border-top-style, border-right-style, border-bottom-style, and border-left-style properties to the value solid.
The width
and height
attributes on applet
, embed
, iframe
, img
, object
or video
elements, and input
elements with a type
attribute in the image button state and that either represents an image
or that the user expects will eventually represent an image, map to the dimension properties width and height on the element
respectively.
10.4.4. Image maps
Shapes on an image map are expected to act, for the purpose of the CSS cascade, as
elements independent of the original area
element that happen to match the same style
rules but inherit from the img
or object
element.
For the purposes of the rendering, only the cursor property is expected to have any effect on the shape.
Thus, for example, if an area
element has a style
attribute that sets the cursor property to help, then when the
user designates that shape, the cursor would change to a Help cursor.
Similarly, if an area
element had a CSS rule that set its cursor property to inherit (or if no rule setting the cursor property matched the element at all),
the shape’s cursor would be inherited from the img
or object
element of
the image map, not from the parent of the area
element.
10.5. Bindings
10.5.1. Introduction
Exactly how the bindings are implemented is not specified by this specification. User agents are encouraged to make their bindings set the appearance CSS property appropriately to achieve platform-native appearances for widgets, and are expected to implement any relevant animations, etc, that are appropriate for the platform. [CSS-UI-3]
10.5.2. The button
element
When the button binding applies to a button
element, the element
is expected to render as an inline-block box rendered as a button whose contents are the
contents of the element.
When the button
element’s type
attribute is
in the Menu state, the user agent is expected to
indicate that activating the element will display a menu, e.g., by displaying a down-pointing
triangle after the button’s label.
10.5.3. The details
element
When the details binding applies to a details
element, the element
is expected to render as a block box with its padding-left property set to "40px" for
left-to-right elements (LTR-specific) and with its padding-right property set to
"40px" for right-to-left elements. The element’s shadow tree is expected to take the element’s
first child summary
element, if any, and place it in a first block box container,
and then take the element’s remaining descendants, if any, and place them in a second block box
container.
The first container is expected to contain at least one line box, and that line box is expected
to contain a disclosure widget (typically a triangle), horizontally positioned within the left
padding of the details
element. That widget is expected to allow the user to request
that the details be shown or hidden.
The second container is expected to have its overflow property set to hidden. When the details
element does not have an open
attribute, this second container is expected to be removed from the rendering.
10.5.4. The input
element as a text entry widget
When the input-textfield binding applies to an input
element whose type
attribute is in the Text, Search, Telephone, URL,
or E-mail state, the element is expected to render as
an inline-block box rendered as a text field.
When the input-password binding applies to an input
element whose type
attribute is in the Password state, the element is expected to render as an inline-block box rendered as a text field whose contents are obscured.
If these text fields provide a text selection, then, when the user changes the current
selection in such a binding, the user agent is expected to queue a task to fire
a simple event that bubbles named select
at the element,
using the user interaction task source as the task source.
If an input
element whose type
attribute is
in one of the above states has a size
attribute, and parsing
that attribute’s value using the rules for parsing non-negative integers doesn’t
generate an error, then the user agent is expected to use the attribute as a presentational hint for the width property on the element,
with the value obtained from applying the converting a character width to pixels algorithm to the value of the attribute.
If an input
element whose type
attribute is
in one of the above states does not have a size
attribute, then the user agent is expected to act as if it had a user-agent-level style sheet rule
setting the width property on the element to the value obtained from applying the converting a character width to pixels algorithm to the number 20.
The converting a character width to pixels algorithm returns (size-1)×avg + max, where size is the character width to convert, avg is the average character width of the primary font for the element for which the algorithm is being run, in pixels, and max is the maximum character width of that same font, also in pixels. (The element’s letter-spacing property does not affect the result.)
When the input-textfield binding applies to an element, the line-height property, if it has a computed value equivalent to a value that is less than 1.0, must have a used value of 1.0.
10.5.5. The input
element as domain-specific widgets
When the input-date binding applies to an input
element whose type
attribute is in the Date state, the element is expected to render as an inline-block box depicting a Date control.
When the input-month binding applies to an input
element whose type
attribute is in the Month state, the element is expected to render as an inline-block box depicting a Month control.
When the input-week binding applies to an input
element whose type
attribute is in the Week state, the element is expected to render as an inline-block box depicting a Week control.
When the input-time binding applies to an input
element whose type
attribute is in the Time state, the element is expected to render as an inline-block box depicting a Time control.
When the input-datetime-local binding applies to an input
element
whose type
attribute is in the Local Date and Time state, the element is expected
to render as an inline-block box depicting a Local Date and Time control.
When the input-number binding applies to an input
element whose type
attribute is in the Number state, the element is expected to render as an inline-block box depicting a Number control.
These controls are all expected to be about one line high, and about as wide as necessary to show the widest possible value.
10.5.6. The input
element as a range control
When the input-range binding applies to an input
element whose type
attribute is in the Range state, the element is
expected to render as an inline-block box depicting a slider control.
When the control is wider than it is tall (or square), the control is expected to be a horizontal slider, with the lowest value on the right if the direction property on this element has a computed value of rtl, and on the left otherwise. When the control is taller than it is wide, it is expected to be a vertical slider, with the lowest value on the bottom.
Predefined suggested values (provided by the list
attribute) are expected to be shown as tick marks on the slider, which the slider can snap to.
User agents are expected to use the used value of the direction property on the element to determine the direction in which the slider operates. Typically, a left-to-right (ltr) horizontal control would have the lowest value on the left and the highest value on the right, and vice versa.
10.5.7. The input
element as a color well
When the input-color binding applies to an input
element whose type
attribute is in the Color state, the element is expected to render as an inline-block box depicting a color well, which, when activated, provides the user with a color
picker (e.g., a color wheel or color palette) from which the color can be changed.
Predefined suggested values (provided by the list
attribute) are expected to be shown in the color picker interface, not on the color well
itself.
10.5.8. The input
element as a checkbox and radio button widgets
When the input-checkbox binding applies to an input
element whose type
attribute is in the Checkbox state, the element is expected to render as an inline-block box containing a single checkbox control, with no label.
When the input-radio binding applies to an input
element whose type
attribute is in the Radio Button state, the element is expected to render as an inline-block box containing a single radio button control, with no label.
10.5.9. The input
element as a file upload control
When the input-file binding applies to an input
element whose type
attribute is in the File Upload state, the element is expected to render as an inline-block box containing a span of text giving the file name(s) of the selected files, if any, followed by a button that,
when activated, provides the user with a file picker from which the selection can be changed.
10.5.10. The input
element as a button
When the input-button binding applies to an input
element whose type
attribute is in the submit button, Reset Button, or Button state, the element is
expected to render as an inline-block box rendered as a button, about one line high, containing
the contents of the element’s value
attribute, if any, or
text derived from the element’s type
attribute in a
user-agent-defined (and probably locale-specific) fashion, if not.
10.5.11. The marquee
element
When the marquee binding applies to a marquee
element, while the
element is turned on, the element is expected to render in
an animated fashion according to its attributes as follows:
- If the element’s
behavior
attribute is in the scroll state -
Slide the contents of the element in the direction described by the
direction
attribute as defined below, such that it begins off the start side of themarquee
, and ends flush with the inner end side.For example, if the
direction
attribute isleft
(the default), then the contents would start such that their left edge are off the side of the right edge of themarquee
’s content area, and the contents would then slide up to the point where the left edge of the contents are flush with the left inner edge of themarquee
’s content area.Once the animation has ended, the user agent is expected to increment the marquee current loop index. If the element is still turned on after this, then the user agent is expected to restart the animation.
- If the element’s
behavior
attribute is in the slide state -
Slide the contents of the element in the direction described by the
direction
attribute as defined below, such that it begins off the start side of themarquee
, and ends off the end side of themarquee
.For example, if the
direction
attribute isleft
(the default), then the contents would start such that their left edge are off the side of the right edge of themarquee
's content area, and the contents would then slide up to the point where the right edge of the contents are flush with the left inner edge of themarquee
's content area.Once the animation has ended, the user agent is expected to increment the marquee current loop index. If the element is still turned on after this, then the user agent is expected to restart the animation.
- If the element’s
behavior
attribute is in the alternate state -
When the marquee current loop index is even (or zero), slide the contents of the element in the direction described by the
direction
attribute as defined below, such that it begins flush with the start side of themarquee
, and ends flush with the end side of themarquee
.When the marquee current loop index is odd, slide the contents of the element in the opposite direction than that described by the
direction
attribute as defined below, such that it begins flush with the end side of themarquee
, and ends flush with the start side of themarquee
.For example, if the
direction
attribute isleft
(the default), then the contents would with their right edge flush with the right inner edge of themarquee
’s content area, and the contents would then slide up to the point where the left edge of the contents are flush with the left inner edge of themarquee
’s content area.Once the animation has ended, the user agent is expected to increment the marquee current loop index. If the element is still turned on after this, then the user agent is expected to continue the animation.
The direction
attribute has the meanings described
in the following table:
direction attribute state
| Direction of animation | Start edge | End edge | Opposite direction |
---|---|---|---|---|
left
| ← Right to left | Right | Left | → Left to Right |
right
| → Left to Right | Left | Right | ← Right to left |
up
| ↑ Up (Bottom to Top) | Bottom | Top | ↓ Down (Top to Bottom) |
down
| ↓ Down (Top to Bottom) | Top | Bottom | ↑ Up (Bottom to Top) |
In any case, the animation should proceed such that there is a delay given by the marquee scroll interval between each frame, and such that the content moves at most the distance given by the marquee scroll distance with each frame.
When a marquee
element has a bgcolor
attribute set, the value is expected to be parsed using the rules for parsing a legacy color
value, and if that does not return an error, the user agent is expected to treat the
attribute as a presentational hint setting the element’s background-color property to the resulting color.
The width
and height
attributes on a marquee
element map to the dimension properties width and height on the element respectively.
The intrinsic height of a marquee
element with its direction
attribute in the up
or down
states is 200 CSS pixels.
The vspace
attribute of a marquee
element maps to the dimension properties margin-top and margin-bottom on the element. The hspace
attribute
of a marquee
element maps to the
dimension properties margin-left and margin-right on the element.
The overflow property on the marquee
element is expected to be ignored; overflow
is expected to always be hidden.
10.5.12. The meter
element
When the meter binding applies to a meter
element, the element is
expected to render as an inline-block box with a height of "1em" and a width of "5em", a vertical-align of "-0.2em", and with its contents depicting a gauge.
When the element is wider than it is tall (or square), the depiction is expected to be of a horizontal gauge, with the minimum value on the right if the direction property on this element has a computed value of rtl, and on the left otherwise. When the element is taller than it is wide, it is expected to depict a vertical gauge, with the minimum value on the bottom.
User agents are expected to use a presentation consistent with platform conventions for gauges, if any.
Requirements for what must be depicted in the gauge are included in the definition
of the meter
element.
10.5.13. The progress
element
When the progress binding applies to a progress
element, the
element is expected to render as an inline-block box with a height of "1em" and a width of
"10em", and a vertical-align of "-0.2em".
When the element is wider than it is tall, the element is expected to be depicted as a horizontal progress bar, with the start on the right and the end on the left if the direction property on this element has a computed value of rtl, and with the start on the left and the end on the right otherwise. When the element is taller than it is wide, it is expected to be depicted as a vertical progress bar, with the lowest value on the bottom. When the element is square, it is expected to be depicted as a direction-independent progress widget (e.g., a circular progress ring).
User agents are expected to use a presentation consistent with platform conventions for progress bars. In particular, user agents are expected to use different presentations for determinate and indeterminate progress bars. User agents are also expected to vary the presentation based on the dimensions of the element.
For example, on some platforms for showing indeterminate progress there is a "spinner" progress indicator with square dimensions, which could be used when the element is square, and an indeterminate progress bar, which could be used when the element is wide.
Requirements for how to determine if the progress bar is determinate or
indeterminate, and what progress a determinate progress bar is to show, are included in the
definition of the progress
element.
10.5.14. The select
element
When the select binding applies to a select
element whose multiple
attribute is present, the element is expected to
render as a multi-select list box.
When the select binding applies to a select
element whose multiple
attribute is absent, and the element’s display size is greater than 1, the element is expected to
render as a single-select list box.
When the element renders as a list box, it is expected to render as an inline-block box whose height is the height necessary to contain as many rows for items as given by the element’s display size, or four rows if the attribute is absent, and
whose width is the width of the select
’s labels plus the width of a
scrollbar.
When the select binding applies to a select
element whose multiple
attribute is absent, and the element’s display size is 1, the element is expected to render as a
one-line drop down box whose width is the width of the select
’s
labels.
In either case (list box or drop-down box), the element’s items are expected to be the
element’s list of options, with the element’s optgroup
element children providing headers for groups of options where
applicable.
An optgroup
element is expected to be rendered by displaying the element’s label
attribute.
An option
element is expected to be rendered by displaying the element’s label, indented under its optgroup
element if it
has one.
The width of the select
’s labels is the wider of the width necessary to
render the widest optgroup
, and the width necessary to render the widest option
element in the element’s list of
options (including its indent, if any).
If a select
element contains a placeholder label option, the user
agent is expected to render that option
in a manner that conveys that it is a label,
rather than a valid option of the control. This can include preventing the placeholder label
option from being explicitly selected by the user. When the placeholder label
option’s selectedness is true, the control
is expected to be displayed in a fashion that indicates that no valid option is currently
selected.
User agents are expected to render the labels in a select
in such a manner that
any alignment remains consistent whether the label is being displayed as part of the page or in a
menu control.
10.5.15. The textarea
element
@namespace url(http://www.w3.org/1999/xhtml); textarea { white-space: pre-wrap; }
When the textarea binding applies to a textarea
element, the
element is expected to render as an inline-block box rendered as a multiline text field. If this
text field provides a selection, then, when the user changes the current selection in such a
binding, the user agent is expected to queue a task to fire a simple
event that bubbles named select
at the element, using
the user interaction task source as the task source.
If the element has a cols
attribute, and parsing that
attribute’s value using the rules for parsing non-negative integers doesn’t generate
an error, then the user agent is expected to use the attribute as a presentational hint for the width property on the element, with the value being
the textarea effective width (as defined below). Otherwise, the user agent is
expected to act as if it had a user-agent-level style sheet rule setting the width property on
the element to the textarea effective width.
The textarea effective width of a textarea
element is size×avg + sbw, where size is the element’s character width, avg is the average
character width of the primary font of the element, in CSS pixels, and sbw is
the width of a scroll bar, in CSS pixels. (The element’s letter-spacing property does not affect
the result.)
If the element has a rows
attribute, and parsing that
attribute’s value using the rules for parsing non-negative integers doesn’t generate
an error, then the user agent is expected to use the attribute as a presentational hint for the height property on the element, with the value being
the textarea effective height (as defined below). Otherwise, the user agent is
expected to act as if it had a user-agent-level style sheet rule setting the height property on
the element to the textarea effective height.
The textarea effective height of a textarea
element is the height in
CSS pixels of the number of lines specified the element’s character height, plus the height of a scrollbar in CSS
pixels.
User agents are expected to apply the white-space CSS property to textarea
elements. For historical reasons, if the element has a wrap
attribute whose value is an ASCII
case-insensitive match for the string "off
", then the user agent is expected to treat the attribute as a presentational hint setting the element’s white-space property to pre.
10.5.16. The keygen
element
When the keygen binding applies to a keygen
element, the element
is expected to render as an inline-block box containing a user interface to configure the key
pair to be generated.
10.6. Frames and framesets
User agent are expected to render frameset
elements as a box with the height and
width of the viewport, with a surface rendered according to the following layout algorithm:
-
The cols and rows variables are lists of zero or more pairs consisting of a number and a unit, the unit being one of percentage, relative, and absolute.
Use the rules for parsing a list of dimensions to parse the value of the element’s
cols
attribute, if there is one. Let cols be the result, or an empty list if there is no such attribute.Use the rules for parsing a list of dimensions to parse the value of the element’s
rows
attribute, if there is one. Let rows be the result, or an empty list if there is no such attribute. -
For any of the entries in cols or rows that have the number zero and the unit relative, change the entry’s number to one.
-
If cols has no entries, then add a single entry consisting of the value 1 and the unit relative to cols.
If rows has no entries, then add a single entry consisting of the value 1 and the unit relative to rows.
-
Invoke the algorithm defined below to convert a list of dimensions to a list of pixel values using cols as the input list, and the width of the surface that the
frameset
is being rendered into, in CSS pixels, as the input dimension. Let sized cols be the resulting list.Invoke the algorithm defined below to convert a list of dimensions to a list of pixel values using rows as the input list, and the height of the surface that the
frameset
is being rendered into, in CSS pixels, as the input dimension. Let sized rows be the resulting list. -
Split the surface into a grid of w×h rectangles, where w is the number of entries in sized cols and h is the number of entries in sized rows.
Size the columns so that each column in the grid is as many CSS pixels wide as the corresponding entry in the sized cols list.
Size the rows so that each row in the grid is as many CSS pixels high as the corresponding entry in the sized rows list.
-
Let children be the list of
frame
andframeset
elements that are children of theframeset
element for which the algorithm was invoked. -
For each row of the grid of rectangles created in the previous step, from top to bottom, run these substeps:
-
For each rectangle in the row, from left to right, run these substeps:
-
If there are any elements left in children, take the first element in the list, and assign it to the rectangle.
If this is a
frameset
element, then recurse the entireframeset
layout algorithm for thatframeset
element, with the rectangle as the surface.Otherwise, it is a
frame
element; render its nested browsing context, positioned and sized to fit the rectangle. -
If there are any elements left in children, remove the first element from children.
-
-
-
If the
frameset
element has a border, draw an outer set of borders around the rectangles, using the element’s frame border color.For each rectangle, if there is an element assigned to that rectangle, and that element has a border, draw an inner set of borders around that rectangle, using the element’s frame border color.
For each (visible) border that does not abut a rectangle that is assigned a
frame
element with anoresize
attribute (including rectangles in further nestedframeset
elements), the user agent is expected to allow the user to move the border, resizing the rectangles within, keeping the proportions of any nestedframeset
grids.A
frameset
orframe
element has a border if the following algorithm returns true:- If the element has a
frameborder
attribute whose value is not the empty string and whose first character is either a U+0031 DIGIT ONE (1) character, a U+0079 LATIN SMALL LETTER Y character (y), or a U+0059 LATIN CAPITAL LETTER Y character (Y), then return true. - Otherwise, if the element has a
frameborder
attribute, return false. - Otherwise, if the element has a parent element that is a
frameset
element, then return true if that element has a border, and false if it does not. - Otherwise, return true.
The frame border color of a
frameset
orframe
element is the color obtained from the following algorithm:- If the element has a
bordercolor
attribute, and applying the rules for parsing a legacy color value to that attribute’s value does not result in an error, then return the color so obtained. - Otherwise, if the element has a parent element that is a
frameset
element, then return the frame border color of that element. - Otherwise, return gray.
- If the element has a
The algorithm to convert a list of dimensions to a list of pixel values consists of the following steps:
-
Let input list be the list of numbers and units passed to the algorithm.
Let output list be a list of numbers the same length as input list, all zero.
Entries in output list correspond to the entries in input list that have the same position.
- Let input dimension be the size passed to the algorithm.
-
Let count percentage be the number of entries in input list whose unit is percentage.
Let total percentage be the sum of all the numbers in input list whose unit is percentage.
Let count relative be the number of entries in input list whose unit is relative.
Let total relative be the sum of all the numbers in input list whose unit is relative.
Let count absolute be the number of entries in input list whose unit is absolute.
Let total absolute be the sum of all the numbers in input list whose unit is absolute.
Let remaining space be the value of input dimension.
-
If total absolute is greater than remaining space, then for each entry in input list whose unit is absolute, set the corresponding value in output list to the number of the entry in input list multiplied by remaining space and divided by total absolute. Then, set remaining space to zero.
Otherwise, for each entry in input list whose unit is absolute, set the corresponding value in output list to the number of the entry in input list. Then, decrement remaining space by total absolute.
-
If total percentage multiplied by the input dimension and divided by 100 is greater than remaining space, then for each entry in input list whose unit is percentage, set the corresponding value in output list to the number of the entry in input list multiplied by remaining space and divided by total percentage. Then, set remaining space to zero.
Otherwise, for each entry in input list whose unit is percentage, set the corresponding value in output list to the number of the entry in input list multiplied by the input dimension and divided by 100. Then, decrement remaining space by total percentage multiplied by the input dimension and divided by 100.
-
For each entry in input list whose unit is relative, set the corresponding value in output list to the number of the entry in input list multiplied by remaining space and divided by total relative.
- Return output list.
User agents working with integer values for frame widths (as opposed to user agents that can lay frames out with subpixel accuracy) are expected to distribute the remainder first to the last entry whose unit is relative, then equally (not proportionally) to each entry whose unit is percentage, then equally (not proportionally) to each entry whose unit is absolute, and finally, failing all else, to the last entry.
The contents of a frame
element that does not have a frameset
parent
are expected to be rendered as transparent black; the user agent is expected to not render the nested browsing context in this case, and that nested browsing context is expected to have a viewport with zero width and zero height.
10.7. Interactive media
10.7.1. Links, forms, and navigation
User agents are expected to allow the user to control aspects of hyperlink activation and §4.10.22 Form submission, such as which browsing context is to be used for the subsequent navigation.
User agents are expected to allow users to discover the destination of hyperlinks and of forms before triggering their navigation.
User agents may allow users to navigate browsing contexts to the URLs indicated by the cite
attributes on q
, blockquote
, ins
, and del
elements.
User agents may surface hyperlinks created by link
elements in their user
interface.
While link
elements that create hyperlinks will match the ':link' or ':visited' pseudo-classes, will
react to clicks if visible, and so forth, this does not extend to any browser interface constructs
that expose those same links. Activating a link through the browser’s interface, rather than in
the page itself, does not trigger click
events and the like.
10.7.2. The title
attribute
User agents are expected to expose the advisory information of elements upon user request, and to make the user aware of the presence of such information.
On interactive graphical systems where the user can use a pointing device, this could take the form of a tooltip. When the user is unable to use a pointing device, then the user agent is expected to make the content available in some other fashion, e.g., by making the element a focusable area and always displaying the advisory information of the currently focused element, or by showing the advisory information of the elements under the user’s finger on a touch device as the user pans around the screen.
U+000A LINE FEED (LF) characters are expected to cause line breaks in the tooltip; U+0009 CHARACTER TABULATION (tab) characters are expected to render as a non-zero horizontal shift that lines up the next glyph with the next tab stop, with tab stops occurring at points that are multiples of 8 times the width of a U+0020 SPACE character.
title
attribute focusable, and could make any focused element with a title
attribute show its tooltip under the element while the
element has focus. This would allow a user to tab around the document to find all the advisory
text. 10.7.3. Editing hosts
The current text editing caret (i.e., the active range, if it is empty and in an editing host), if any, is expected to act like an inline replaced element with the vertical dimensions of the caret and with zero width for the purposes of the CSS rendering model.
This means that even an empty block can have the caret inside it, and that when the caret is in such an element, it prevents margins from collapsing through the element.
10.7.4. Text rendered in native user interfaces
User agents are expected to honor the Unicode semantics of text that is exposed in user interfaces, for example supporting the bidirectional algorithm in text shown in dialogs, title bars, pop-up menus, and tooltips. Text from the contents of elements is expected to be rendered in a manner that honors the directionality of the element from which the text was obtained. Text from attributes is expected to be rendered in a manner that honours the directionality of the attribute.
<p dir="rtl" lang="he"> <label> בחר שפת תכנות: <select> <option dir="ltr">C++</option> <option dir="ltr">C#</option> <option dir="ltr">FreePascal</option> <option dir="ltr">F#</option> </select> </label> </p>
If the select
element was rendered as a drop down box, a correct rendering would
ensure that the punctuation was the same both in the drop down, and in the box showing the
current selection.
dir
attribute, as the following example demonstrates. Consider this
markup:
<table> <tr> <th abbr="(א" dir=ltr>A <th abbr="(א" dir=rtl>A <th abbr="(א" dir=auto>A </table>
If the abbr
attributes are rendered, e.g., in a tooltip or
other user interface, the first will have a left parenthesis (because the direction is ltr),
the second will have a right parenthesis (because the direction is rtl), and the third will
have a right parenthesis (because the direction is determined from the attribute value to be rtl).
However, if instead the attribute was not a directionality-capable attribute, the results would be different:
<table> <tr> <th>A <th>A <th>A </table>
In this case, if the user agent were to expose the data-abbr
attribute
in the user interface (e.g., in a debugging environment), the last case would be rendered with a left parenthesis, because the direction would be determined from the element’s
contents.
A string provided by a script (e.g., the argument to window.alert()
) is expected to be treated as an independent set of one or
more bidirectional algorithm paragraphs when displayed, as defined by the bidirectional algorithm,
including, for instance, supporting the paragraph-breaking behavior of U+000A LINE FEED (LF)
characters. For the purposes of determining the paragraph level of such text in the bidirectional
algorithm, this specification does not provide a higher-level override of rules P2 and
P3. [BIDI]
When necessary, authors can enforce a particular direction for a given paragraph by starting it with the Unicode U+200E LEFT-TO-RIGHT MARK or U+200F RIGHT-TO-LEFT MARK characters.
alert('\u05DC\u05DE\u05D3 HTML \u05D4\u05D9\u05D5\u05DD!')
...would always result in a message reading "למד LMTH היום!" (not "דמל HTML םויה!"), regardless of the language of the user agent interface or the direction of the page or any of its elements.
/* Warning: this script does not handle right-to-left scripts correctly */ var s; if (s = prompt('What is your name?')) { alert(s + '! Ok, Fred, ' + s + ', and Wilma will get the car.'); }
When the user enters "Kitty", the user agent would alert "Kitty! Ok, Fred, Kitty, and Wilma will get the car.". However, if the user enters "لا أفهم", then the bidirectional algorithm will determine that the direction of the paragraph is right-to-left, and so the output will be the following unintended mess: "لا أفهم! derF ,kO, لا أفهم, rac eht teg lliw amliW dna."
To force an alert that starts with user-provided text (or other text of unknown directionality) to render left-to-right, the string can be prefixed with a U+200E LEFT-TO-RIGHT MARK character:
var s; if (s = prompt('What is your name?')) { alert('\u200E' + s + '! Ok, Fred, ' + s + ', and Wilma will get the car.'); }
10.8. Print media
User agents are expected to allow the user to request the opportunity to obtain a physical
form (or a representation of a physical form) of a Document
. For example,
selecting the option to print a page or convert it to PDF format. [PDF]
When the user actually obtains a physical form (or
a representation of a physical form) of a Document
, the user agent is expected to
create a new rendering of the Document
for the print media.
10.9. Unstyled XML documents
HTML user agents may, in certain circumstances, find themselves rendering non-HTML documents that use vocabularies for which they lack any built-in knowledge. This section provides for a way for user agents to handle such documents in a somewhat useful manner.
While a Document
is an unstyled document, the user agent is expected
to render an unstyled document view.
A Document
is an unstyled document while it matches the following
conditions:
- The
Document
has no author style sheets (whether referenced by HTTP headers, processing instructions, elements likelink
, inline elements likestyle
, or any other mechanism). - None of the elements in the
Document
have any presentational hints. - None of the elements in the
Document
have any CSS styling attributes. - None of the elements in the
Document
are in any of the following namespaces: HTML namespace, SVG namespace, MathML namespace - The
Document
has no focusable area (e.g., from XLink) other than the viewport. - The
Document
has no hyperlinks (e.g., from XLink). - There exists no script whose settings object specifies this
Document
as the responsible document. - None of the elements in the
Document
have any registered event listeners.
An unstyled document view is one where the DOM is not rendered according to CSS
(which would, since there are no applicable styles in this context, just result in a wall of
text), but is instead rendered in a manner that is useful for a developer. This could consist of
just showing the Document
object’s source, maybe with syntax highlighting, or it
could consist of displaying just the DOM tree, or simply a message saying that the page is not a
styled document.
If a Document
stops being an unstyled document, then the
conditions above stop applying, and thus a user agent following these requirements will switch to
using the regular CSS rendering.
11. Obsolete features
11.1. Obsolete but conforming features
Features listed in this section will trigger warnings in conformance checkers.
Authors should not specify a border
attribute on an img
element. If the
attribute is present, its value must be the string "0
". CSS should be used instead.
Authors should not specify a language
attribute on a script
element. If
the attribute is present, its value must be an ASCII case-insensitive match for the string
"JavaScript
" and either the type
attribute must be omitted or its value
must be an ASCII case-insensitive match for the string "text/javascript
".
The attribute should be entirely omitted instead (with the value "JavaScript
", it has
no effect), or replaced with use of the type
attribute.
Authors should not specify the name
attribute on a
elements. If the
attribute is present, its value must not be the empty string and must neither be equal to the
value of any of the IDs in the element’s home subtree other than the element’s own id
, if any, nor be equal to the value of any of the other name
attributes on a
elements in the element’s home subtree. If this attribute is present and the
element has an id
, then the attribute’s value must be equal to the element’s id
. In
earlier versions of the language, this attribute was intended as a way to specify possible targets
for fragment identifiers in URLs. The id
attribute should be used instead.
Authors should not, but may despite requirements to the contrary elsewhere in this specification,
specify the maxlength
and size
attributes on input
elements
whose type
attributes are in the Number state. One
valid reason for using these attributes regardless is to help legacy user agents that do not
support input
elements with type="number"
to still render the text field with a
useful width.
In the HTML syntax, specifying a DOCTYPE that is an obsolete permitted DOCTYPE will also trigger a warning.
11.1.1. Warnings for obsolete but conforming features
To ease the transition from HTML Transitional documents to the language defined in this specification, and to discourage certain features that are only allowed in very few circumstances, conformance checkers must warn the user when the following features are used in a document. These are generally old obsolete features that have no effect, and are allowed only to distinguish between likely mistakes (regular conformance errors) and mere vestigial markup or unusual and discouraged practices (these warnings).
The following features must be categorized as described above:
-
The presence of an obsolete permitted DOCTYPE in an HTML document.
-
The presence of a
border
attribute on animg
element if its value is the string "0
". -
The presence of a
language
attribute on ascript
element if its value is an ASCII case-insensitive match for the string "JavaScript
" and if there is notype
attribute or there is and its value is an ASCII case-insensitive match for the string "text/javascript
". -
The presence of a
name
attribute on ana
element, if its value is not the empty string. -
The presence of a
maxlength
attribute on aninput
element whosetype
attribute is in the Number state. -
The presence of a
size
attribute on aninput
element whosetype
attribute is in the Number state.
Conformance checkers must distinguish between pages that have no conformance errors and have none of these obsolete features, and pages that have no conformance errors but do have some of these obsolete features.
For example, a validator could report some pages as "Valid HTML" and others as "Valid HTML with warnings".
11.2. Non-conforming features
Elements in the following list are entirely obsolete, and must not be used by authors:
-
applet
-
acronym
-
Use
abbr
instead. -
bgsound
-
Use
audio
instead. -
dir
-
Use
ul
instead. -
frame
frameset
noframes
-
Either use
iframe
and CSS instead, or use server-side includes to generate complete pages with the various invariant parts merged in. -
isindex
-
Use an explicit
form
and text field combination instead. -
listing
-
nextid
-
Use GUIDs instead.
-
noembed
-
plaintext
-
Use the "
text/plain
" MIME type instead. -
strike
-
Use
del
instead if the element is marking an edit, otherwise uses
instead. -
xmp
-
Use
pre
andcode
instead, and escape "<
" and "&
" characters as "<
" and "&
" respectively. -
basefont
big
blink
center
font
multicol
nobr
spacer
tt
-
Use appropriate elements or CSS instead.
Where the
tt
element would have been used for marking up keyboard input, consider thekbd
element; for variables, consider thevar
element; for computer code, consider thecode
element; and for computer output, consider thesamp
element.Similarly, if the
big
element is being used to denote a heading, consider using theh1
element; if it is being used for marking up important passages, consider thestrong
element; and if it is being used for highlighting text for reference purposes, consider themark
element.See also the text-level semantics usage summary for more suggestions with examples.
The following attributes are obsolete (though the elements are still part of the language), and must not be used by authors:
-
charset
ona
elementscharset
onlink
elements -
Use an HTTP
Content-Type
header on the linked resource instead. -
coords
ona
elementsshape
ona
elements -
Use
area
instead ofa
for image maps. -
methods
ona
elementsmethods
onlink
elements -
Use the HTTP OPTIONS feature instead.
-
name
ona
elements (except as noted in the previous section)name
onembed
elementsname
onimg
elementsname
onoption
elements -
Use the
id
attribute instead. -
urn
ona
elementsurn
onlink
elements -
Specify the preferred persistent identifier using the
href
attribute instead. -
accept
onform
elements -
Use the
accept
attribute directly on theinput
elements instead. -
type
onarea
elements -
These attributes do not do anything useful, and for historical reasons there are no corresponding IDL attributes on
area
elements. Omit them altogether. -
nohref
onarea
elements -
Omitting the
href
attribute is sufficient; thenohref
attribute is unnecessary. Omit it altogether. -
profile
onhead
elements -
When used for declaring which
meta
terms are used in the document, unnecessary; omit it altogether, and register the names.When used for triggering specific user agent behaviors: use a
link
element instead. -
version
onhtml
elements -
Unnecessary. Omit it altogether.
-
manifest
onhtml
elements -
The use of application caches is not recommended. Alternative mechanisms to support offline applications include the use of [WEBSTORAGE], [IndexedDB], and [SERVICE-WORKERS].
-
ismap
oninput
elements -
Unnecessary. Omit it altogether. All
input
elements with atype
attribute in the image button state are processed as server-side image maps. -
usemap
oninput
elements -
Use
img
instead ofinput
for image maps. -
lowsrc
onimg
elements -
Use a progressive JPEG image (given in the
src
attribute), instead of using two separate images. -
target
onlink
elements -
Unnecessary. Omit it altogether.
-
scheme
onmeta
elements -
Use only one scheme per field, or make the scheme declaration part of the value.
-
archive
onobject
elementsclassid
onobject
elementscode
onobject
elementscodebase
onobject
elementscodetype
onobject
elements -
Use the
data
andtype
attributes to invoke plugins. To set parameters with these names in particular, theparam
element can be used. -
declare
onobject
elements -
Repeat the
object
element completely each time the resource is to be reused. -
standby
onobject
elements -
Optimize the linked resource so that it loads quickly or, at least, incrementally.
-
usemap
onobject
elements -
Use
img
instead ofobject
for image maps. -
type
onparam
elementsvaluetype
onparam
elements -
Use the
name
andvalue
attributes without declaring value types. -
language
onscript
elements (except as noted in the previous section) -
Use the
type
attribute instead. -
event
onscript
elementsfor
onscript
elements -
Use DOM events mechanisms to register event listeners. [DOM]
-
Use script to select the media resource(s) to use.
-
datapagesize
ontable
elements -
Unnecessary. Omit it altogether.
-
summary
ontable
elements -
Use one of the §4.9.1.1 Techniques for describing tables given in the
table
section instead. -
abbr
ontd
elements -
Use text that begins in an unambiguous and terse manner, and include any more elaborate text after that. The
title
attribute can also be useful in including more detailed text, so that the cell’s contents can be made terse. If it’s a heading, useth
(which has anabbr
attribute). -
scope
ontd
elements -
Use
th
elements for heading cells. -
datasrc
ona
,applet
,button
,div
,frame
,iframe
,img
,input
,label
,legend
,marquee
,object
,option
,select
,span
,table
, andtextarea
elementsdatafld
ona
,applet
,button
,div
,fieldset
,frame
,iframe
,img
,input
,label
,legend
,marquee
,object
,param
,select
,span
, andtextarea
elementsdataformatas
onbutton
,div
,input
,label
,legend
,marquee
,object
,option
,select
,span
, andtable
elements -
Use script and a mechanism such as
XMLHttpRequest
to populate the page dynamically. [XHR] -
alink
onbody
elementsbgcolor
onbody
elementsbottommargin
onbody
elementsleftmargin
onbody
elementslink
onbody
elementsmarginheight
onbody
elementsmarginwidth
onbody
elementsrightmargin
onbody
elementstext
onbody
elementsmargintop
onbody
elementsvlink
onbody
elementsclear
onbr
elementsalign
oncaption
elementsalign
oncol
elementschar
oncol
elementscharoff
oncol
elementsvalign
oncol
elementswidth
oncol
elementsalign
ondiv
elementscompact
ondl
elementsalign
onembed
elementshspace
onembed
elementsvspace
onembed
elementsalign
onhr
elementscolor
onhr
elementsnoshade
onhr
elementssize
onhr
elementswidth
onhr
elementsalign
oniframe
elementsallowtransparency
oniframe
elementsframeborder
oniframe
elementsframespacing
oniframe
elementshspace
oniframe
elementsmarginheight
oniframe
elementsmarginwidth
oniframe
elementsscrolling
oniframe
elementsvspace
oniframe
elementsalign
oninput
elementsborder
oninput
elementshspace
oninput
elementsvspace
oninput
elementsalign
onimg
elementsborder
onimg
elements (except as noted in the previous section)hspace
onimg
elementsvspace
onimg
elementsalign
onlegend
elementstype
onli
elementscompact
onmenu
elementsalign
onobject
elementsborder
onobject
elementshspace
onobject
elementsvspace
onobject
elementscompact
onol
elementsalign
onp
elementswidth
onpre
elementsalign
ontable
elementsbgcolor
ontable
elementsborder
ontable
elementsbordercolor
ontable
elementscellpadding
ontable
elementscellspacing
ontable
elementsframe
ontable
elementsheight
ontable
elementsrules
ontable
elementswidth
ontable
elementsalign
ontbody
,thead
, andtfoot
elementschar
ontbody
,thead
, andtfoot
elementscharoff
ontbody
,thead
, andtfoot
elementsvalign
ontbody
,thead
, andtfoot
elementsalign
ontr
elementsbgcolor
ontr
elementschar
ontr
elementscharoff
ontr
elementsheight
ontr
elementsvalign
ontr
elementscompact
onul
elementstype
onul
elementsbackground
onbody
,table
,thead
,tbody
,tfoot
,tr
,td
, andth
elements -
Use CSS instead.
The border
attribute on the table
element can be used to provide basic fallback
styling for the purpose of making tables legible in browsing environments where CSS support is
limited or absent, such as text-based browsers, WYSIWYG editors, and in situations where CSS
support is disabled or the style sheet is lost. Only the empty string and the value
"1
" may be used as border
values for this purpose. Other values are
considered obsolete. To regulate the thickness of such borders, authors should instead use CSS.
11.3. Requirements for implementations
11.3.1. The applet
element
This feature is in the process of being removed from the Web platform. (This is a long process
that takes many years.) Using the applet
element at this time is highly
discouraged.
The applet
element is a Java-specific variant of the embed
element.
The applet
element is now obsoleted so that all extension frameworks (Java, .NET,
Flash, etc) are handled in a consistent manner.
When the element matches any of the following conditions, it represents its contents:
-
The element is still in the stack of open elements of an HTML parser or XML parser.
-
The element is not in a
Document
. -
The element’s node document is not fully active.
-
The element’s node document’s active sandboxing flag set has its sandboxed plugins browsing context flag set.
-
The element has an ancestor media element.
-
The element has an ancestor
object
element that is not showing its fallback content. -
No Java Language runtime plugin is available.
-
A Java runtime plugin is available but it is disabled.
Otherwise, the user agent should instantiate a Java Language runtime plugin, and should
pass the names and values of all the attributes on the element, in the order they were added to
the element, with the attributes added by the parser being ordered in source order, and then a
parameter named "PARAM" whose value is null, and then all the names and values of parameters given by param
elements that are children of the applet
element, in tree order, to the plugin used. If the plugin supports a scriptable interface, the HTMLAppletElement
object representing the
element should expose that interface. The applet
element represents the plugin.
The applet
element is unaffected by the CSS display property. The
Java Language runtime is instantiated even if the element is hidden with a 'display:none' CSS
style.
The applet
element must implement the HTMLAppletElement
interface.
interface HTMLAppletElement : HTMLElement { attribute DOMString align; attribute DOMString alt; attribute DOMString archive; attribute DOMString code; attribute DOMString codeBase; attribute DOMString height; attribute unsigned long hspace; attribute DOMString name; attribute DOMString _object; // the underscore is not part of the identifier attribute unsigned long vspace; attribute DOMString width; };
The align
, alt
, archive
, code
, height
, hspace
, name
, object
, vspace
, and width
IDL attributes must reflect the respective content attributes of the same name. For the purposes of reflection, the applet
element’s object
content attribute is defined as containing a URL.
The codeBase
IDL attribute must reflect the codebase
content attribute, which for the purposes of reflection
is defined as containing a URL.
11.3.2. The marquee
element
The marquee
element is a presentational element that animates content. CSS transitions and
animations are a more appropriate mechanism. [CSS3-ANIMATIONS] [CSS3-TRANSITIONS]
The task source for tasks mentioned in this section is the DOM manipulation task source.
The marquee
element must implement the HTMLMarqueeElement
interface.
interface HTMLMarqueeElement : HTMLElement { attribute DOMString behavior; attribute DOMString bgColor; attribute DOMString direction; attribute DOMString height; attribute unsigned long hspace; attribute long loop; attribute unsigned long scrollAmount; attribute unsigned long scrollDelay; attribute boolean trueSpeed; attribute unsigned long vspace; attribute DOMString width; attribute EventHandler onbounce; attribute EventHandler onfinish; attribute EventHandler onstart; void start(); void stop(); };
A marquee
element can be turned on or turned off. When it is created, it
is turned on.
When the start()
method is called, the marquee
element must be turned on.
When the stop()
method is called, the marquee
element must be turned off.
When a marquee
element is created, the user agent must queue a task to fire a simple event named start
at the element.
The behavior
content attribute on marquee
elements is an enumerated attribute with the following keywords (all non-conforming):
Keyword | State |
---|---|
scroll
| scroll |
slide
| slide |
alternate
| alternate |
The missing value default is the scroll state.
The direction
content attribute on marquee
elements is an enumerated attribute with the following keywords (all non-conforming):
Keyword | State |
---|---|
left
| left |
right
| right |
up
| up |
down
| down |
The missing value default is the left state.
The truespeed
content attribute on marquee
elements is a boolean attribute.
A marquee
element has a marquee scroll interval, which is obtained as follows:
-
If the element has a
scrolldelay
content attribute, and parsing its value using the rules for parsing non-negative integers does not return an error, then let delay be the parsed value. Otherwise, let delay be 85. -
If the element does not have a
truespeed
attribute, and the delay value is less than 60, then let delay be 60 instead. -
The marquee scroll interval is delay, interpreted in milliseconds.
A marquee
element has a marquee scroll distance, which, if the
element has a scrollamount
content attribute,
and parsing its value using the rules for parsing non-negative integers does not return an
error, is the parsed value interpreted in CSS pixels, and otherwise is 6 CSS pixels.
A marquee
element has a marquee loop count, which, if the element has a loop
content attribute, and parsing its value
using the rules for parsing integers does not return an error or a number less than 1, is
the parsed value, and otherwise is -1.
The loop
IDL attribute, on getting,
must return the element’s marquee loop count; and on setting, if the new value is different
than the element’s marquee loop count and either greater than zero or equal to -1, must set
the element’s loop
content attribute (adding it if necessary) to the valid integer that represents the new value. (Other values are ignored.)
A marquee
element also has a marquee current loop index, which is zero when the
element is created.
The rendering layer will occasionally increment the marquee current loop index, which must cause the following steps to be run:
-
If the marquee loop count is -1, then abort these steps.
-
Increment the marquee current loop index by one.
-
If the marquee current loop index is now equal to or greater than the element’s marquee loop count, turn off the
marquee
element and queue a task to fire a simple event namedfinish
at themarquee
element.Otherwise, if the
behavior
attribute is in the alternate state, then queue a task to fire a simple event namedbounce
at themarquee
element.Otherwise, queue a task to fire a simple event named
start
at themarquee
element.
The following are the event handlers (and their corresponding event handler event types) that must be supported, as event handler content attributes and event handler IDL attributes, by marquee
elements:
Event handler | Event handler event type |
---|---|
onbounce
| bounce
|
onfinish
| finish
|
onstart
| start
|
The behavior
, direction
, height
, hspace
, vspace
,
and width
IDL attributes must reflect the respective content attributes of the same name.
The bgColor
IDL attribute must reflect the bgcolor
content attribute.
The scrollAmount
IDL attribute must reflect the scrollamount
content attribute. The default value is 6.
The scrollDelay
IDL attribute must reflect the scrolldelay
content attribute. The default value is 85.
The trueSpeed
IDL attribute must reflect the truespeed
content attribute.
11.3.3. Frames
The frameset
element acts as the body
element in documents
that use frames.
The frameset
element must implement the HTMLFrameSetElement
interface.
interface HTMLFrameSetElement : HTMLElement { attribute DOMString cols; attribute DOMString rows; }; HTMLFrameSetElement implements WindowEventHandlers;
The cols
and rows
IDL attributes of the frameset
element must reflect the respective content attributes of the same name.
The frameset
element exposes as event handler content attributes a number of the event handlers of the Window
object. It also mirrors their event handler IDL attributes.
The onblur
, onerror
, onfocus
, onload
, onresize
, and onscroll
event handlers of the Window
object, exposed on the frameset
element, replace the generic event handlers with the same names normally supported by html elements.
The frame
element defines a nested browsing context similar
to the iframe
element, but rendered within a frameset
element.
A frame
element is said to be an active frame
element when it is in a Document
.
When a frame
element is created as an active frame
element, or becomes an active frame
element after not having been one, the user agent must create a nested browsing context, and then process the frame
attributes for the
first time.
When a frame
element stops being an active frame
element, the
user agent must discard the nested browsing context.
Whenever a frame
element with a nested browsing context has its src
attribute
set, changed, or removed, the user agent must process the frame
attributes.
When the user agent is to process the frame
attributes, it must run the
first appropriate steps from the following list:
- If the element has no
src
attribute specified, and the user agent is processing theframe
's attributes for the first time - Queue a task to fire a simple event named
load
at theframe
element. - Otherwise
-
-
If the value of the
src
attribute is the empty string, let url be the string "about:blank
".Otherwise, resolve the value of the
src
attribute, relative to theframe
element.If that is not successful, then let url be the string "
about:blank
". Otherwise, let url be the resulting absolute URL. -
Navigate the element’s child browsing contextto url.
-
Furthermore, if the active document of the element’s child browsing context before such a navigation was not completely loaded at the time of the new navigation, then the navigation must be completed with replacement enabled.
Similarly, if the child browsing context’s session history contained only one Document
when the process the frame
attributes algorithm was
invoked, and that was the about:blank
Document
created when the child
browsing context was created, then any navigation required of the user agent in that
algorithm must be completed with replacement enabled.
When a Document
in a frame
is marked as completely loaded, the user agent
must queue a task to fire a simple event named load
at the frame
element.
The task source for the tasks above is the DOM manipulation task source.
When a frame
element’s nested browsing context’s active document is not ready for post-load tasks, and when anything is delaying the load event of the frame
element’s browsing context’s active document, and when the frame
element’s browsing context is in the delaying load
events mode, the frame
must delay the load event of its document.
When the browsing context is created, if a name
content attribute is present, the browsing context name must be set to the value of this
attribute; otherwise, the browsing context name must be set to the empty string.
Whenever the name
attribute is set, the nested browsing context’s name must be changed to the new value. If the attribute is
removed, the browsing context name must be set to the empty string.
The frame
element must implement the HTMLFrameElement
interface.
interface HTMLFrameElement : HTMLElement { attribute DOMString name; attribute DOMString scrolling; attribute DOMString src; attribute DOMString frameBorder; attribute boolean noResize; readonly attribute Document? contentDocument; readonly attribute WindowProxy? contentWindow; [TreatNullAs=EmptyString] attribute DOMString marginHeight; [TreatNullAs=EmptyString] attribute DOMString marginWidth; };
The name
, scrolling
, and src
IDL attributes of the frame
element must reflect the respective content attributes of the same name. For the purposes
of reflection, the frame
element’s src
content attribute is defined as containing a URL.
The frameBorder
IDL attribute of the frame
element must reflect the element’s frameborder
content attribute.
The noResize
IDL attribute of the frame
element must reflect the element’s noresize
content attribute.
The contentDocument
IDL attribute of the frame
element must return the Document
object of the active document of the frame
element’s nested browsing context, if any and if its origin is the same origin-domain as the origin specified by the incumbent settings object, or null otherwise.
The contentWindow
IDL attribute must
return the WindowProxy
object of the frame
element’s nested browsing context.
The marginHeight
IDL attribute of the frame
element must reflect the element’s marginheight
content attribute.
The marginWidth
IDL attribute of the frame
element must reflect the element’s marginwidth
content attribute.
11.3.4. Application caches
An application cache is a set of cached resources consisting of:
-
One or more resources (including their out-of-band metadata, such as HTTP headers, if any), identified by URLs, each falling into one (or more) of the following categories:
- Master entries
-
These are documents that were added to the cache because a browsing context was navigated to that document and the document indicated that this was its cache, using the
manifest
attribute. - The manifest
-
This is the resource corresponding to the URL that was given in a master entry’s
html
element’smanifest
attribute. The manifest is fetched and processed during the application cache download process. All the master entries have the same origin as the manifest. - Explicit entries
-
These are the resources that were listed in the cache’s manifest in an explicit section.
- Fallback entries
-
These are the resources that were listed in the cache’s manifest in a fallback section.
Explicit entries and Fallback entries can be marked as foreign, which means that they have a
manifest
attribute but that it doesn’t point at this cache’s manifest.A URL in the list can be flagged with multiple different types, and thus an entry can end up being categorized as multiple entries. For example, an entry can be a manifest entry and an explicit entry at the same time, if the manifest is listed within the manifest.
-
Zero or more fallback namespaces, each of which is mapped to a fallback entry.
These are URLs used as prefix match patterns for resources that are to be fetched from the network if possible, or to be replaced by the corresponding fallback entry if not. Each namespace URL has the same origin as the manifest.
-
Zero or more URLs that form the online safelist namespaces.
These are used as prefix match patterns, and declare URLs for which the user agent will ignore the application cache, instead fetching them normally (i.e., from the network or local HTTP cache as appropriate).
-
An online safelist wildcard flag, which is either open or blocking.
The open state indicates that any URL not listed as cached is to be implicitly treated as being in the online safelist namespaces; the blocking state indicates that URLs not listed explicitly in the manifest are to be treated as unavailable.
-
A cache mode flag, which is either in the fast state or the prefer-online state.
Each application cache has a completeness flag, which is either complete or incomplete.
An application cache group is a group of application caches, identified by the absolute URL of a resource manifest which is used to populate the caches in the group.
An application cache is newer than another if it was created after the other (in other words, application caches in an application cache group have a chronological order).
Only the newest application cache in an application cache group can have its completeness flag set to incomplete; the others are always all complete.
Each application cache group has an update status, which is one of the following: idle, checking, downloading.
A relevant application cache is an application cache that is the newest in its group to be complete.
Each application cache group has a list of pending master entries. Each entry in this
list consists of a resource and a corresponding Document
object. It is used during
the application cache download process to ensure that new master entries are cached
even if the application cache download process was already running for their application cache group when they were loaded.
An application cache group can be marked as obsolete, meaning that it must be ignored when looking at what application cache groups exist.
A cache host is a Document
or a SharedWorkerGlobalScope
object. A cache host can be associated with an application cache.
A Document
initially is not associated with an application cache, but
can become associated with one early during the page load process, when steps in the parser and in the navigation sections cause cache selection to occur.
A SharedWorkerGlobalScope
can be associated with an application cache when it is created.
Each cache host has an associated ApplicationCache
object.
Multiple application caches in different application cache groups can contain the same resource, e.g., if the manifests all reference that resource. If the user agent is to select an application cache from a list of relevant application caches that contain a resource, the user agent must use the application cache that the user most likely wants to see the resource from, taking into account the following:
- which application cache was most recently updated,
- which application cache was being used to display the resource from which the user decided to look at the new resource, and
- which application cache the user prefers.
A URL matches a fallback namespace if there exists a relevant application cache whose manifest’s URL has the same origin as the URL in question, and that has a fallback namespace that is a prefix match for the URL being examined. If multiple fallback namespaces match the same URL, the longest one is the one that matches. A URL looking for a fallback namespace can match more than one application cache at a time, but only matches one namespace in each cache.
11.3.4.1. Parsing cache manifests
When a user agent is to parse a manifest, it means that the user agent must run the following steps:
-
UTF-8 decode the byte stream corresponding with the manifest to be parsed.
The UTF-8 decode algorithm strips a leading BOM, if any.
- Let base URL be the absolute URL representing the manifest.
- Apply the URL parser to base URL, and let manifest path be the path component thus obtained.
- Remove all the characters in manifest path after the last U+002F SOLIDUS character (/), if any. (The first character and the last character in manifest path after this step will both be slashes, the URL path separator character.)
- Apply the URL parser steps to the base URL, so that the components from its URL record can be used by the subsequent steps of this algorithm.
- Let explicit URLs be an initially empty list of absolute URLs for explicit entries.
- Let fallback URLs be an initially empty mapping of fallback namespaces to absolute URLs for fallback entries.
- Let online safelist namespaces be an initially empty list of absolute URLs for an online safelist.
- Let online safelist wildcard flag be blocking.
- Let cache mode flag be fast.
- Let input be the decoded text of the manifest’s byte stream.
- Let position be a pointer into input, initially pointing at the first character.
- If the characters starting from position are "CACHE", followed by a U+0020 SPACE character, followed by "MANIFEST", then advance position to the next character after those. Otherwise, this isn’t a cache manifest; abort this algorithm with a failure while checking for the magic signature.
- If the character at position is neither a U+0020 SPACE character, a U+0009 CHARACTER TABULATION (tab) character, U+000A LINE FEED (LF) character, nor a U+000D CARRIAGE RETURN (CR) character, then this isn’t a cache manifest; abort this algorithm with a failure while checking for the magic signature.
- This is a cache manifest. The algorithm cannot fail beyond this point (though bogus lines can get ignored).
- Collect a sequence of characters that are not U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters, and ignore those characters. (Extra text on the first line, after the signature, is ignored.)
- Let mode be "explicit".
- Start of line: If position is past the end of input, then jump to the last step. Otherwise, collect a sequence of characters that are U+000A LINE FEED (LF), U+000D CARRIAGE RETURN (CR), U+0020 SPACE, or U+0009 CHARACTER TABULATION (tab) characters.
- Now, collect a sequence of characters that are not U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters, and let the result be line.
- Drop any trailing U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters at the end of line.
- If line is the empty string, then jump back to the step labeled start of line.
- If the first character in line is a U+0023 NUMBER SIGN character (#), then jump back to the step labeled Start of line.
- If line equals "CACHE:" (the word "CACHE" followed by a U+003A COLON character (:)), then set mode to "explicit" and jump back to the step labeled Start of line.
- If line equals "FALLBACK:" (the word "FALLBACK" followed by a U+003A COLON character (:)), then set mode to "fallback" and jump back to the step labeled Start of line.
- If line equals "NETWORK:" (the word "NETWORK" followed by a U+003A COLON character (:)), then set mode to "online safelist" and jump back to the step labeled Start of line.
- If line equals "SETTINGS:" (the word "SETTINGS" followed by a U+003A COLON character (:)), then set mode to "settings" and jump back to the step labeled Start of line.
- If line ends with a U+003A COLON character (:), then set mode to "unknown" and jump back to the step labeled Start of line.
- This is either a data line or it is syntactically incorrect.
- Let position be a pointer into line, initially pointing at the start of the string.
- Let tokens be a list of strings, initially empty.
-
While position doesn’t point past the end of line:
- Let current token be an empty string.
- While position doesn’t point past the end of line and the character at position is neither a U+0020 SPACE nor a U+0009 CHARACTER TABULATION (tab) character, add the character at position to current token and advance position to the next character in input.
- Add current token to the tokens list.
- While position doesn’t point past the end of line and the character at position is either a U+0020 SPACE or a U+0009 CHARACTER TABULATION (tab) character, advance position to the next character in input.
-
Process tokens as follows:
- If mode is "explicit"
-
Let urlRecord be the result of parsing the first item in tokens, with base URL; ignore the rest.
If urlRecord is failure, then jump back to the step labeled Start of line.
If urlRecord has a different scheme component than base URL (the manifest’s URL), then jump back to the step labeled Start of line.
Let new URL be the result of applying the URL serializer algorithm to urlRecord, with the exclude fragment flag set.
Add new URL to the explicit URLs.
- If mode is "fallback"
-
Let part one be the first token in tokens, and let part two be the second token in tokens.
Let urlRecordOne be the result of parsing part one with base URL.
Let urlRecordTwo be the result of parsing part two with base URL.
If either urlRecordOne or urlRecordTwo is failure, then jump back to the step labeled Start of line.
If the origin of either urlRecordOne or urlRecordTwo is not same origin with the manifest’s URL origin, then jump back to the step labeled Start of line.
Let part one path be the path component of urlRecordOne.
If manifest path is not a prefix match for part one path, then jump back to the step labeled Start of line.
Let part one be the result of applying the URL serializer algorithm to urlRecordOne, with the exclude fragment flag set.
Let part two be the result of applying the URL serializer algorithm to urlRecordTwo, with the exclude fragment flag set.
If part one is already in the fallback URLs mapping as a fallback namespace, then jump back to the step labeled Start of line.
Otherwise, add part one to the fallback URLs mapping as a fallback namespace, mapped to part two as the fallback entry.
- If mode is "online safelist"
-
If the first item in tokens is a U+002A ASTERISK character (*), then set online safelist wildcard flag to open and jump back to the step labeled Start of line.
Otherwise, let urlRecord be the result of parsing the first item in tokens with base URL.
If urlRecord is failure, then jump back to the step labeled Start of line.
If urlRecord has a different scheme component than base URL (the manifest’s URL), then jump back to the step labeled Start of line.
Let new URL be the result of applying the URL serializer algorithm to urlRecord, with the exclude fragment flag set.
Add new URL to the online safelist namespaces.
- If mode is "settings"
-
If tokens contains a single token, and that token is a case-sensitive match for the string "
prefer-online
", then set cache mode flag to prefer-online and jump back to the step labeled Start of line.Otherwise, the line is an unsupported setting: do nothing; the line is ignored.
- If mode is "unknown"
-
Do nothing. The line is ignored.
- Jump back to the step labeled Start of line. (That step jumps to the next, and last, step when the end of the file is reached.)
- Return the explicit URLs list, the fallback URLs mapping, the online safelist namespaces, the online safelist wildcard flag, and the cache mode flag.
11.3.4.2. Downloading or updating an application cache
When the user agent is required (by other parts of this specification) to start the application cache download process for an absolute URL purported to identify a manifest, or for an application cache group, potentially given a particular cache host, and potentially given a master resource, the user agent must run the steps below. These steps are always run in parallel with the event loop tasks.
Some of these steps have requirements that only apply if the user agent shows caching
progress. Support for this is optional. Certain events
fired during the application cache download process allow the script to override the
display of such an interface. (Such events are delayed until after the load
event has fired.)
User agents are encouraged not to show prominent update progress notifications for applications that cancel the relevant events.
The application cache download process steps are as follows:
- Optionally, wait until the permission to start the application cache download process has been obtained from the user and until the user agent is confident that the network is available. This could include doing nothing until the user explicitly opts-in to caching the site, or could involve prompting the user for permission. The algorithm might never get past this point. (This step is particularly intended to be used by user agents running on severely space-constrained devices or in highly privacy-sensitive environments).
-
Atomically, so as to avoid race conditions, perform the following substeps:
-
Pick the appropriate substeps:
- If these steps were invoked with an absolute URL purported to identify a manifest
-
Let manifest URL be that absolute URL.
If there is no application cache group identified by manifest URL, then create a new application cache group identified by manifest URL. Initially, it has no application caches. One will be created later in this algorithm.
- If these steps were invoked with an application cache group
-
Let manifest URL be the absolute URL of the manifest used to identify the application cache group to be updated.
If that application cache group is obsolete, then abort this instance of the application cache download process. This can happen if another instance of this algorithm found the manifest to be 404 or 410 while this algorithm was waiting in the first step above.
- Let cache group be the application cache group identified by manifest URL.
- If these steps were invoked with a master resource, then add the resource, along with the resource’s
Document
, to cache group’s list of pending master entries. - If these steps were invoked with a cache host, and the status of cache group is checking or downloading, then queue a post-load task to fire a
simple event named
checking
that is cancelable at theApplicationCache
singleton of that cache host. The default action of this event must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the user agent is checking to see if it can download the application. - If these steps were invoked with a cache host, and the status of cache group is downloading, then also queue a post-load task to fire a simple
event named
downloading
that is cancelable at theApplicationCache
singleton of that cache host. The default action of this event must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user the application is being downloaded. - If the status of the cache group is either checking or downloading, then abort this instance of the application cache download process, as an update is already in progress.
- Set the status of cache group to checking.
- For each cache host associated with an application cache in cache group, queue a post-load task to fire a simple
event that is cancelable named
checking
at theApplicationCache
singleton of the cache host. The default action of these events must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the user agent is checking for the availability of updates.
The remainder of the steps run in parallel.
If cache group already has an application cache in it, then this is an upgrade attempt. Otherwise, this is a cache attempt.
-
- If this is a cache attempt, then this
algorithm was invoked with a cache host; queue a post-load task to fire a simple event named
checking
that is cancelable at theApplicationCache
singleton of that cache host. The default action of this event must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the user agent is checking for the availability of updates. - Let request be a new request whose URL is manifest URL, client is null, destination is "
subresource
", omit-Origin
-header flag is set, referrer is "no-referrer
", synchronous flag is set, credentials mode is "include
", and whose use-URL-credentials flag is set. -
Fetching the manifest: Let manifest be the result of fetching request. HTTP caching semantics should be honored for this request.
Parse manifest’s body according to the rules for parsing manifests, obtaining a list of explicit entries, fallback entries and the fallback namespaces that map to them, entries for the online safelist, and values for the online safelist wildcard flag and the cache mode flag.
The MIME type of the resource is ignored — it is assumed to be
text/cache-manifest
. In the future, if new manifest formats are supported, the different types will probably be distinguished on the basis of the file signatures (for the current format, that is the "CACHE MANIFEST
" string at the top of the file). -
If fetching the manifest fails due to a 404 or 410 response status, then run these substeps:
- Mark cache group as obsolete. This cache group no
longer exists for any purpose other than the processing of
Document
objects already associated with an application cache in the cache group. - Let task list be an empty list of tasks.
- For each cache host associated with an application cache in cache group, create a task to fire
a simple event named
obsolete
that is cancelable at theApplicationCache
singleton of the cache host, and append it to task list. The default action of these events must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the application is no longer available for offline use. - For each entry in cache group’s list of pending master entries, create a task to fire a simple event that is cancelable named
error
(notobsolete
!) at theApplicationCache
singleton of theDocument
for this entry, if there still is one, and append it to task list. The default action of this event must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the user agent failed to save the application for offline use. - If cache group has an application cache whose completeness flag is incomplete, then discard that application cache.
- If appropriate, remove any user interface indicating that an update for this cache is in progress.
- Let the status of cache group be idle.
- For each task in task list, queue that task as a post-load task.
- Abort the application cache download process.
- Mark cache group as obsolete. This cache group no
longer exists for any purpose other than the processing of
-
Otherwise, if fetching the manifest fails in some other way (e.g., the server returns another 4xx or 5xx response, or there is a DNS error, or the connection times out, or the user cancels the download, or the parser for manifests fails when checking the magic signature), or if the server returned a redirect, then run the cache failure steps. [HTTP]
-
If this is an upgrade attempt and the newly downloaded manifest is byte-for-byte identical to the manifest found in the newest application cache in cache group, or the response status is
304
, then run these substeps:- Let cache be the newest application cache in cache group.
- Let task list be an empty list of tasks.
-
For each entry in cache group’s list of pending master entries, wait for the resource for this entry to have either completely downloaded or failed.
If the download failed (e.g., the server returns a 4xx or 5xx response, or there is a DNS error, the connection times out, or the user cancels the download), or if the resource is labeled with the "no-store" cache directive, then create a task to fire a simple event that is cancelable named
error
at theApplicationCache
singleton of theDocument
for this entry, if there still is one, and append it to task list. The default action of this event must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the user agent failed to save the application for offline use.Otherwise, associate the
Document
for this entry with cache; store the resource for this entry in cache, if it isn’t already there, and categorize its entry as a master entry. If applying the URL parser algorithm to the resource’s URL results in a resulting URL record that has a non-null fragment component, the URL used for the entry in cache must instead be the absolute URL obtained from applying the URL serializer algorithm to the resulting URL record with the exclude fragment flag set (application caches never include fragment identifiers). - For each cache host associated with an application cache in cache group, create a task to fire
a simple event that is cancelable named
noupdate
at theApplicationCache
singleton of the cache host, and append it to task list. The default action of these events must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the application is up to date. - Empty cache group’s list of pending master entries.
- If appropriate, remove any user interface indicating that an update for this cache is in progress.
- Let the status of cache group be idle.
- For each task in task list, queue that task as a post-load task.
- Abort the application cache download process.
- Let new cache be a newly created application cache in cache group. Set its completeness flag to incomplete.
- For each entry in cache group’s list of pending master entries, associate the
Document
for this entry with new cache. - Set the status of cache group to downloading.
- For each cache host associated with an application cache in cache group, queue a post-load task to fire a simple
event that is cancelable named
downloading
at theApplicationCache
singleton of the cache host. The default action of these events must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that a new version is being downloaded. - Let file list be an empty list of URLs with flags.
- Add all the URLs in the list of explicit entries obtained by parsing manifest to file list, each flagged with "explicit entry".
- Add all the URLs in the list of fallback entries obtained by parsing manifest to file list, each flagged with "fallback entry".
- If this is an upgrade attempt, then add all the URLs of master entries in the newest application cache in cache group whose completeness flag is complete to file list, each flagged with "master entry".
- If any URL is in file list more than once, then merge the entries into one entry for that URL, that entry having all the flags that the original entries had.
-
For each URL in file list, run the following steps. These steps may be run in parallel for two or more of the URLs at a time. If, while running these steps, the
ApplicationCache
object’sabort()
method sends a signal to this instance of the application cache download process algorithm, then run the cache failure steps instead.-
If the resource URL being processed was flagged as neither an "explicit entry" nor or a "fallback entry", then the user agent may skip this URL.
This is intended to allow user agents to expire resources not listed in the manifest from the cache. Generally, implementors are urged to use an approach that expires lesser-used resources first.
- For each cache host associated with an application cache in cache group, queue a progress post-load task to fire a trusted event with the name
progress
, which does not bubble, which is cancelable, and which uses theProgressEvent
interface, at theApplicationCache
singleton of the cache host. ThelengthComputable
attribute must be set to true, thetotal
attribute must be set to the number of files in file list, and theloaded
attribute must be set to the number of files in file list that have been either downloaded or skipped so far. The default action of these events must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that a file is being downloaded in preparation for updating the application. [XHR] - Let request be a new request whose URL is URL, client is null, destination is
"
subresource
", origin is manifest URL’s origin, referrer is "no-referrer
", synchronous flag is set, credentials mode is "include
", use-URL-credentials flag is set, and redirect mode is "manual
". - Fetch request. If this is an upgrade attempt, then use the newest application cache in cache group as an HTTP cache, and honor HTTP caching semantics (such as expiration, ETags, and so forth) with respect to that cache. User agents may also have other caches in place that are also honored.
-
If the previous step fails (e.g., the server returns a 4xx or 5xx response, or there is a DNS error, or the connection times out, or the user cancels the download), or if the server returned a redirect, or if the resource is labeled with the "no-store" cache directive, then run the first appropriate step from the following list: [HTTP]
- If the URL being processed was flagged as an "explicit entry" or a "fallback entry"
-
If these steps are being run in parallel for any other URLs in file list, then abort these steps for those other URLs. Run the cache failure steps.
Redirects are fatal because they are either indicative of a network problem (e.g., a captive portal); or would allow resources to be added to the cache under URLs that differ from any URL that the networking model will allow access to, leaving orphan entries; or would allow resources to be stored under URLs different than their true URLs. All of these situations are bad.
- If the error was a 404 or 410 HTTP response
- If the resource was labeled with the "no-store" cache directive
-
Skip this resource. It is dropped from the cache.
- Otherwise
-
Copy the resource and its metadata from the newest application cache in cache group whose completeness flag is complete, and act as if that was the fetched resource, ignoring the resource obtained from the network.
These rules make errors for resources listed in the manifest fatal, while making it possible for other resources to be removed from caches when they are removed from the server, without errors, and making non-manifest resources survive server-side errors.
Except for the "no-store" directive, HTTP caching rules that would cause a file to be expired or otherwise not cached are ignored for the purposes of the application cache download process.
-
Otherwise, the fetching succeeded. Store the resource in the new cache.
If the user agent is not able to store the resource (e.g., because of quota restrictions), the user agent may prompt the user or try to resolve the problem in some other manner (e.g., automatically pruning content in other caches). If the problem cannot be resolved, the user agent must run the cache failure steps.
- If the URL being processed was flagged as an "explicit entry" in file list, then categorize the entry as an explicit entry.
- If the URL being processed was flagged as a "fallback entry" in file list, then categorize the entry as a fallback entry.
- If the URL being processed was flagged as an "master entry" in file list, then categorize the entry as a master entry.
- As an optimization, if the resource is an HTML or XML file whose root element is an
html
element with amanifest
attribute whose value doesn’t match the manifest URL of the application cache being processed, then the user agent should mark the entry as being foreign.
-
- For each cache host associated with an application cache in cache group, queue a progress post-load task to fire a trusted event with the name
progress
, which does not bubble, which is cancelable, and which uses theProgressEvent
interface, at theApplicationCache
singleton of the cache host. ThelengthComputable
attribute must be set to true, thetotal
and theloaded
attributes must be set to the number of files in file list. The default action of these events must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that all the files have been downloaded. [XHR] - Store the list of fallback namespaces, and the URLs of the fallback entries that they map to, in new cache.
- Store the URLs that form the new online safelist in new cache.
- Store the value of the new online safelist wildcard flag in new cache.
- Store the value of the new cache mode flag in new cache.
-
For each entry in cache group’s list of pending master entries, wait for the resource for this entry to have either completely downloaded or failed.
If the download failed (e.g., the server returns a 4xx or 5xx response, or there is a DNS error, the connection times out, or the user cancels the download), or if the resource is labeled with the "no-store" cache directive, then run these substeps:
- Unassociate the
Document
for this entry from new cache. - Queue a post-load task to fire a simple event that is
cancelable named
error
at theApplicationCache
singleton of theDocument
for this entry, if there still is one. The default action of this event must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the user agent failed to save the application for offline use. -
If this is a cache attempt and this entry is the last entry in cache group’s list of pending master entries, then run these further substeps:
- Discard cache group and its only application cache, new cache.
- If appropriate, remove any user interface indicating that an update for this cache is in progress.
- Abort the application cache download process.
- Otherwise, remove this entry from cache group’s list of pending master entries.
Otherwise, store the resource for this entry in new cache, if it isn’t already there, and categorize its entry as a master entry.
- Unassociate the
- Let request be a new request whose URL is manifest URL, client is null, destination is "
subresource
", referrer is "no-referrer
", synchronous flag is set, credentials mode is "include
", and whose use-URL-credentials flag is set. -
Let second manifest be the result of fetching request. HTTP caching semantics should again be honored for this request.
-
If the previous step failed for any reason, or if the fetching attempt involved a redirect, or if second manifest and manifest are not byte-for-byte identical, then schedule a rerun of the entire algorithm with the same parameters after a short delay, and run the cache failure steps.
-
Otherwise, store manifest in new cache, if it’s not there already, and categorize its entry as the manifest.
- Set the completeness flag of new cache to complete.
- Let task list be an empty list of tasks.
-
If this is a cache attempt, then for each cache host associated with an application cache in cache group, create a task to fire a simple event that is cancelable named
cached
at theApplicationCache
singleton of the cache host, and append it to task list. The default action of these events must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the application has been cached and that they can now use it offline.Otherwise, it is an upgrade attempt. For each cache host associated with an application cache in cache group, create a task to fire a simple event that is cancelable named
updateready
at theApplicationCache
singleton of the cache host, and append it to task list. The default action of these events must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that a new version is available and that they can activate it by reloading the page. - If appropriate, remove any user interface indicating that an update for this cache is in progress.
- Set the update status of cache group to idle.
- For each task in task list, queue that task as a post-load task.
The cache failure steps are as follows:
- Let task list be an empty list of tasks.
-
For each entry in cache group’s list of pending master entries, run the following further substeps. These steps may be run in parallel for two or more entries at a time.
- Wait for the resource for this entry to have either completely downloaded or failed.
- Unassociate the
Document
for this entry from its application cache, if it has one. - Create a task to fire a simple event that
is cancelable named
error
at theApplicationCache
singleton of theDocument
for this entry, if there still is one, and append it to task list. The default action of these events must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the user agent failed to save the application for offline use.
- For each cache host still associated with an application cache in cache group, create a task to fire
a simple event that is cancelable named
error
at theApplicationCache
singleton of the cache host, and append it to task list. The default action of these events must be, if the user agent shows caching progress, the display of some sort of user interface indicating to the user that the user agent failed to save the application for offline use. - Empty cache group’s list of pending master entries.
- If cache group has an application cache whose completeness flag is incomplete, then discard that application cache.
- If appropriate, remove any user interface indicating that an update for this cache is in progress.
- Let the status of cache group be idle.
- If this was a cache attempt, discard cache group altogether.
- For each task in task list, queue that task as a post-load task.
- Abort the application cache download process.
Attempts to fetch resources as part of the application cache download process may be done with cache-defeating semantics, to avoid problems with stale or inconsistent intermediary caches.
User agents may invoke the application cache download process, in the background, for any application cache group, at any time (with no cache host). This allows user agents to keep caches primed and to update caches even before the user visits a site.
Each Document
has a list of pending application cache download process
tasks that is used to delay events fired by the algorithm above until the document’s load
event has fired. When the Document
is created, the
list must be empty.
When the steps above say to queue a post-load task task, where task is a task that dispatches an event on a
target ApplicationCache
object target, the user agent must run
the appropriate steps from the following list:
- If target’s node document is ready for post-load tasks
- Queue the task task.
- Otherwise
- Add task to target’s node document’s list of pending application cache download process tasks.
When the steps above say to queue a progress post-load task task, where task is a task that dispatches an event on a
target ApplicationCache
object target, the user agent must run
the following steps:
- If there is a task in target’s node document’s list of pending application cache download process tasks that is labeled as a progress task, then remove that task from the list.
- Label task as a progress task.
- Queue a post-load task task.
The task source for these tasks is the networking task source.
11.3.4.3. The application cache selection algorithm
When the application cache selection algorithm algorithm is invoked with a Document
document and optionally a
manifest URL manifest URL, the user agent must run the first
applicable set of steps from the following list:
- If there is a manifest URL, and document was loaded from an application cache, and the URL of the manifest of that cache’s application cache group is not the same as manifest URL
-
Mark the entry for the resource from which document was taken in the application cache from which it was loaded as foreign.
Restart the current navigation from the top of the navigation algorithm, undoing any changes that were made as part of the initial load (changes can be avoided by ensuring that the step to update the session history with the new page is only ever completed after this application cache selection algorithm is run, though this is not required).
- If document was loaded from an application cache, and that application cache still exists (it is not now obsolete)
-
Associate document with the application cache from which it was loaded. Invoke, in the background, the application cache download process for that application cache’s application cache group, with document as the cache host.
- If document was loaded using
GET
, and, there is a manifest URL, and manifest URL has the same origin as document -
Invoke, in the background, the application cache download process for manifest URL, with document as the cache host and with the resource from which document was parsed as the master resource.
If there are relevant application caches that are identified by a URL with the same origin as the URL of document, and that have this URL as one of their entries, excluding entries marked as foreign, then the user agent should use the most appropriate application cache of those that match as an HTTP cache for any subresource loads. User agents may also have other caches in place that are also honored.
- Otherwise
-
The
Document
is not associated with any application cache.If there was a manifest URL, the user agent may report to the user that it was ignored, to aid in application development.
11.3.4.4. Changes to the networking model
When a cache host is associated with an application cache whose completeness flag is complete, any and all loads for resources related to that cache host other than those for child browsing contexts must go through the following steps instead of immediately invoking the mechanisms appropriate to that resource’s scheme:
- If the resource is not to be fetched using the GET method, or if applying the URL parser algorithm to both its URL and the application cache’s manifest’s URL results in two URL records with different scheme components, then fetch the resource normally and abort these steps.
- If the resource’s URL is a master entry, the manifest, an explicit entry, or a fallback entry in the application cache, then get the resource from the cache (instead of fetching it), and abort these steps.
- If there is an entry in the application cache’s online safelist that has the same origin as the resource’s URL and that is a prefix match for the resource’s URL, then fetch the resource normally and abort these steps.
-
If the resource’s URL has the same origin as the manifest’s URL, and there is a fallback namespace f in the application cache that is a prefix match for the resource’s URL, then:
Fetch the resource normally. If this results in a redirect to a resource with another origin (indicative of a captive portal), or a 4xx or 5xx status code, or if there were network errors (but not if the user canceled the download), then instead get, from the cache, the resource of the fallback entry corresponding to the fallback namespace f. Abort these steps.
- If the application cache’s online safelist wildcard flag is open, then fetch the resource normally and abort these steps.
- Fail the resource load as if there had been a generic network error.
The above algorithm ensures that so long as the online safelist wildcard flag is blocking, resources that are not present in the manifest will always fail to load (at least, after the application cache has been primed the first time), making the testing of offline applications simpler.
11.3.4.5. Expiring application caches
As a general rule, user agents should not expire application caches, except on request from the user, or after having been left unused for an extended period of time.
Application caches and cookies have similar implications with respect to privacy (e.g., if the site can identify the user when providing the cache, it can store data in the cache that can be used for cookie resurrection). Implementors are therefore encouraged to expose application caches in a manner related to HTTP cookies, allowing caches to be expunged together with cookies and other origin-specific data.
11.3.4.6. Disk space
User agents should consider applying constraints on disk usage of application caches, and care should be taken to ensure that the restrictions cannot be easily worked around using subdomains.
User agents should allow users to see how much space each domain is using, and may offer the user the ability to delete specific application caches.
11.3.4.7. Security concerns with offline applications caches
This section is non-normative.
The main risk introduced by offline application caches is that an injection attack can be elevated into persistent site-wide page replacement. This attack involves using an injection vulnerability to upload two files to the victim site. The first file is an application cache manifest consisting of just a fallback entry pointing to the second file, which is an HTML page whose manifest is declared as that first file. Once the user has been directed to that second file, all subsequent accesses to any file covered by the given fallback namespace while either the user or the site is offline will instead show that second file. Targeted denial-of-service attacks or cookie bombing attacks (where the client is made to send so many cookies that the server refuses to process the request) can be used to ensure that the site appears offline.
To mitigate this, manifests can only specify fallbacks that are in the same path as the manifest itself. This means that a content injection upload vulnerability in a particular directory on a server can only be escalated to a take-over of that directory and its subdirectories. If there is no way to inject a file into the root directory, the entire site cannot be taken over.
If a site has been attacked in this way, simply removing the offending manifest might eventually clear the problem, since the next time the manifest is updated, a 404 error will be seen, and the user agent will clear the cache. "Eventually" is the key word here, however; while the attack on the user or server is ongoing, such that connections from an affected user to the affected site are blocked, the user agent will simply assume that the user is offline and will continue to use the hostile manifest. Unfortunately, if a cookie bombing attack has also been used, merely removing the manifest is insufficient; in addition, the server has to be configured to return a 404 or 410 response instead of the 413 "Request Entity Too Large" response.
TLS does not inherently protect a site from this attack, since the attack relies on content being served from the server itself. Not using application caches also does not prevent this attack, since the attack relies on an attacker-provided manifest.
11.3.4.8. Application cache API
[Exposed=(Window, SharedWorker)] interface ApplicationCache : EventTarget { // update status const unsigned short UNCACHED = 0; const unsigned short IDLE = 1; const unsigned short CHECKING = 2; const unsigned short DOWNLOADING = 3; const unsigned short UPDATEREADY = 4; const unsigned short OBSOLETE = 5; readonly attribute unsigned short status; // updates void update(); void abort(); void swapCache(); // events attribute EventHandler onchecking; attribute EventHandler onerror; attribute EventHandler onnoupdate; attribute EventHandler ondownloading; attribute EventHandler onprogress; attribute EventHandler onupdateready; attribute EventHandler oncached; attribute EventHandler onobsolete; };
- cache = window .
applicationCache
-
(In a window.) Returns the
ApplicationCache
object that applies to the active document of thatWindow
. - cache = self .
applicationCache
-
(In a shared worker.) Returns the
ApplicationCache
object that applies to the current shared worker. - cache .
status
-
Returns the current status of the application cache, as given by the constants defined below.
- cache .
update
() -
Invokes the application cache download process.
Throws an
InvalidStateError
exception if there is no application cache to update. - cache .
abort
() -
Cancels the application cache download process.
- cache .
swapCache
() -
Switches to the most recent application cache, if there is a newer one. If there isn’t, throws an
InvalidStateError
exception.
There is a one-to-one mapping from cache hosts to ApplicationCache
objects. The applicationCache
attribute on Window
objects must return the ApplicationCache
object associated with the Window
object’s active document. The applicationCache
attribute
on SharedWorkerGlobalScope
objects must return the ApplicationCache
object associated with the worker.
A Window
or SharedWorkerGlobalScope
object has an
associated ApplicationCache
object even if that cache host has no actual application cache.
The status
attribute, on getting, must
return the current state of the application cache that the ApplicationCache
object’s cache host is associated with, if any. This
must be the appropriate value from the following list:
UNCACHED
(numeric value 0)- The
ApplicationCache
object’s cache host is not associated with an application cache at this time. IDLE
(numeric value 1)- The
ApplicationCache
object’s cache host is associated with an application cache whose application cache group’s update status is idle, and that application cache is the newest cache in its application cache group, and the application cache group is not marked as obsolete. CHECKING
(numeric value 2)- The
ApplicationCache
object’s cache host is associated with an application cache whose application cache group’s update status is checking. DOWNLOADING
(numeric value 3)- The
ApplicationCache
object’s cache host is associated with an application cache whose application cache group’s update status is downloading. UPDATEREADY
(numeric value 4)- The
ApplicationCache
object’s cache host is associated with an application cache whose application cache group’s update status is idle, and whose application cache group is not marked as obsolete, but that application cache is not the newest cache in its group. OBSOLETE
(numeric value 5)- The
ApplicationCache
object’s cache host is associated with an application cache whose application cache group is marked as obsolete.
If the update()
method is invoked, the user
agent must invoke the application cache download process, in the background, for the application cache group of the application cache with which the ApplicationCache
object’s cache host is associated, but without giving
that cache host to the algorithm. If there is no such application cache,
or if its application cache group is marked as obsolete, then the method must throw an InvalidStateError
exception instead.
If the abort()
method is invoked, the user
agent must send a signal to the current application cache download process for the application cache group of the application cache with which the ApplicationCache
object’s cache host is associated, if any. If there is
no such application cache, or it does not have a current application cache
download process, then do nothing.
If the swapCache()
method is invoked,
the user agent must run the following steps:
- Check that
ApplicationCache
object’s cache host is associated with an application cache. If it is not, then throw anInvalidStateError
exception and abort these steps. - Let cache be the application cache with which the
ApplicationCache
object’s cache host is associated. (By definition, this is the same as the one that was found in the previous step.) - If cache’s application cache group is marked as obsolete, then unassociate the
ApplicationCache
object’s cache host from cache and abort these steps. (Resources will now load from the network instead of the cache.) - Check that there is an application cache in the same application cache group as cache whose completeness
flag is complete and that is newer than cache. If there is not, then throw an
InvalidStateError
exception and abort these steps. - Let new cache be the newest application cache in the same application cache group as cache whose completeness flag is complete.
- Unassociate the
ApplicationCache
object’s cache host from cache and instead associate it with new cache.
The following are the event handlers (and their corresponding event handler event types) that must be supported, as event handler IDL attributes, by all objects implementing the ApplicationCache
interface:
Event handler | Event handler event type |
---|---|
onchecking
| checking
|
onerror
| error
|
onnoupdate
| noupdate
|
ondownloading
| downloading
|
onprogress
| progress
|
onupdateready
| updateready
|
oncached
| cached
|
onobsolete
| obsolete
|
11.3.5. Other elements, attributes and APIs
User agents must treat acronym
elements in a manner equivalent to abbr
elements in terms
of semantics and for purposes of rendering.
partial interface HTMLAnchorElement { attribute DOMString coords; attribute DOMString charset; attribute DOMString name; attribute DOMString shape; };
The coords
, charset
, name
, and shape
IDL attributes of the th
element must reflect the respective content attributes of the same name.
partial interface HTMLAreaElement { attribute boolean noHref; };
The noHref
IDL attribute of the area
element must reflect the element’s nohref
content attribute.
partial interface HTMLBodyElement { [TreatNullAs=EmptyString] attribute DOMString text; [TreatNullAs=EmptyString] attribute DOMString link; [TreatNullAs=EmptyString] attribute DOMString vLink; [TreatNullAs=EmptyString] attribute DOMString aLink; [TreatNullAs=EmptyString] attribute DOMString bgColor; attribute DOMString background; };
The text
IDL attribute of the body
element must reflect the element’s text
content attribute.
The link
IDL attribute of the body
element must reflect the element’s link
content attribute.
The aLink
IDL attribute of the body
element must reflect the element’s alink
content attribute.
The vLink
IDL attribute of the body
element must reflect the element’s vlink
content attribute.
The bgColor
IDL attribute of the body
element must reflect the element’s bgcolor
content attribute.
The background
IDL attribute of the body
element must reflect the element’s background
content attribute. (The background
content is not defined to contain a URL, despite
rules regarding its handling in §10 Rendering above.)
partial interface HTMLBRElement { attribute DOMString clear; };
The clear
IDL attribute of the br
element must reflect the content attribute of the same name.
partial interface HTMLTableCaptionElement { attribute DOMString align; };
The align
IDL attribute of the caption
element must reflect the content attribute of the same name.
partial interface HTMLTableColElement { attribute DOMString align; attribute DOMString ch; attribute DOMString chOff; attribute DOMString vAlign; attribute DOMString width; };
The align
and width
IDL attributes of the col
element must reflect the respective content attributes of the same name.
The ch
IDL attribute of the col
element must reflect the element’s char
content attribute.
The chOff
IDL attribute of the col
element must reflect the element’s charoff
content attribute.
The vAlign
IDL attribute of the col
element must reflect the element’s valign
content attribute.
User agents must treat dir
elements in a manner equivalent to ul
elements in terms of semantics and for purposes of rendering.
The dir
element must implement the HTMLDirectoryElement
interface.
interface HTMLDirectoryElement : HTMLElement { attribute boolean compact; };
The compact
IDL attribute of the dir
element must reflect the content attribute of the same name.
partial interface HTMLDivElement { attribute DOMString align; };
The align
IDL attribute of the div
element must reflect the content attribute of the same name.
partial interface HTMLDListElement { attribute boolean compact; };
The compact
IDL attribute of the dl
element must reflect the content attribute of the same name.
partial interface HTMLEmbedElement { attribute DOMString align; attribute DOMString name; };
The name
and align
IDL attributes of the embed
element must reflect the respective content attributes of the same name.
The font
element must implement the HTMLFontElement
interface.
interface HTMLFontElement : HTMLElement { [TreatNullAs=EmptyString] attribute DOMString color; attribute DOMString face; attribute DOMString size; };
The color
, face
, and size
IDL attributes of the font
element must reflect the respective content
attributes of the same name.
partial interface HTMLHeadingElement { attribute DOMString align; };
The align
IDL attribute of the h1
–h6
elements must reflect the content attribute of the same name.
The profile
IDL attribute on head
elements (with the HTMLHeadElement
interface) is intentionally omitted. Unless so required
by another applicable specification, implementations would
therefore not support this attribute. (It is mentioned here as it was defined in a previous
version of the DOM specifications.)
partial interface HTMLHRElement { attribute DOMString align; attribute DOMString color; attribute boolean noShade; attribute DOMString size; attribute DOMString width; };
The align
, color
, size
,
and width
IDL attributes of the hr
element must reflect the respective content attributes of the same name.
The noShade
IDL attribute of the hr
element must reflect the element’s noshade
content attribute.
partial interface HTMLHtmlElement { attribute DOMString version; };
The version
IDL attribute of the html
element must reflect the content attribute of the same name.
partial interface HTMLIFrameElement { attribute DOMString align; attribute DOMString scrolling; attribute DOMString frameBorder; [TreatNullAs=EmptyString] attribute DOMString marginHeight; [TreatNullAs=EmptyString] attribute DOMString marginWidth; };
The align
and scrolling
IDL attributes of the iframe
element must reflect the respective content attributes of the same name.
The frameBorder
IDL attribute of the iframe
element must reflect the element’s frameborder
content attribute.
The marginHeight
IDL attribute of the iframe
element must reflect the element’s marginheight
content attribute.
The marginWidth
IDL attribute of the iframe
element must reflect the element’s marginwidth
content attribute.
partial interface HTMLImageElement { attribute DOMString name; attribute DOMString lowsrc; attribute DOMString align; attribute unsigned long hspace; attribute unsigned long vspace; [TreatNullAs=EmptyString] attribute DOMString border; };
The name
, align
, border
, hspace
, and vspace
IDL attributes of the img
element must reflect the respective content attributes of the same name.
The lowsrc
IDL attribute of the img
element must reflect the element’s lowsrc
content attribute, which for the
purposes of reflection is defined as containing a URL.
partial interface HTMLInputElement { attribute DOMString align; attribute DOMString useMap; };
The align
IDL attribute of the input
element must reflect the content attribute of the same name.
The useMap
IDL attribute of the input
element must reflect the element’s usemap
content attribute.
partial interface HTMLLegendElement { attribute DOMString align; };
The align
IDL attribute of the legend
element must reflect the content attribute of the same name.
partial interface HTMLLIElement { attribute DOMString type; };
The type
IDL attribute of the li
element
must reflect the content attribute of the same name.
partial interface HTMLLinkElement { attribute DOMString charset; attribute DOMString target; };
The charset
and target
IDL attributes of the link
element must reflect the respective content attributes of the same name.
User agents must treat listing
elements in a manner equivalent to pre
elements in
terms of semantics and for purposes of rendering.
partial interface HTMLMenuElement { attribute boolean compact; };
The compact
IDL attribute of the menu
element must reflect the content attribute of the same name.
partial interface HTMLMetaElement { attribute DOMString scheme; };
User agents may treat the scheme
content attribute
on the meta
element as an extension of the element’s name
content attribute when
processing a meta
element with a name
attribute whose value is one that the user
agent recognizes as supporting the scheme
attribute.
User agents are encouraged to ignore the scheme
attribute and instead process the
value given to the metadata name as if it had been specified for each expected value of the scheme
attribute.
meta
elements with name
attributes having the value "eGMS.subject.keyword", and knows that the scheme
attribute is used with this metadata name, then it could take the scheme
attribute
into account, acting as if it was an extension of the name
attribute. Thus the
following two meta
elements could be treated as two elements giving values for two
different metadata names, one consisting of a combination of "eGMS.subject.keyword" and "LGCL",
and the other consisting of a combination of "eGMS.subject.keyword" and "ORLY":
<!-- this markup is invalid --> <meta name="eGMS.subject.keyword" scheme="LGCL" content="Abandoned vehicles"> <meta name="eGMS.subject.keyword" scheme="ORLY" content="Mah car: kthxbye">
The suggested processing of this markup, however, would be equivalent to the following:
<meta name="eGMS.subject.keyword" content="Abandoned vehicles"> <meta name="eGMS.subject.keyword" content="Mah car: kthxbye">
The scheme
IDL attribute of the meta
element must reflect the content attribute of the same name.
partial interface HTMLObjectElement { attribute DOMString align; attribute DOMString archive; attribute DOMString code; attribute boolean declare; attribute unsigned long hspace; attribute DOMString standby; attribute unsigned long vspace; attribute DOMString codeBase; attribute DOMString codeType; attribute DOMString useMap; [TreatNullAs=EmptyString] attribute DOMString border; };
The align
, archive
, border
, code
, declare
, hspace
, standby
, and vspace
IDL attributes of the object
element must reflect the respective content attributes of the same name.
The codeBase
IDL attribute of the object
element must reflect the element’s codebase
content attribute,
which for the purposes of reflection is defined as containing a URL.
The codeType
IDL attribute of the object
element must reflect the element’s codetype
content attribute.
The useMap
IDL attribute of the object
element must reflect the element’s usemap
content attribute.
partial interface HTMLOListElement { attribute boolean compact; };
The compact
IDL attribute of the ol
element must reflect the content attribute of the same name.
partial interface HTMLParagraphElement { attribute DOMString align; };
The align
IDL attribute of the p
element must reflect the content attribute of the same name.
partial interface HTMLParamElement { attribute DOMString type; attribute DOMString valueType; };
The type
IDL attribute of the param
element must reflect the content attribute of the same name.
The valueType
IDL attribute of the param
element must reflect the element’s valuetype
content attribute.
User agents must treat plaintext
elements in a manner equivalent to pre
elements
in terms of semantics and for purposes of rendering. (The parser has special behavior for this
element, though.)
partial interface HTMLPreElement { attribute long width; };
The width
IDL attribute of the pre
element must reflect the content attribute of the same name.
partial interface HTMLScriptElement { attribute DOMString event; attribute DOMString htmlFor; };
The event
IDL attribute of the script
element must reflect the element’s event
content attribute.
The htmlFor
IDL attribute of the script
element must reflect the element’s for
content attribute.
partial interface HTMLTableElement { attribute DOMString align; attribute DOMString border; attribute DOMString frame; attribute DOMString rules; attribute DOMString summary; attribute DOMString width; [TreatNullAs=EmptyString] attribute DOMString bgColor; [TreatNullAs=EmptyString] attribute DOMString cellPadding; [TreatNullAs=EmptyString] attribute DOMString cellSpacing; };
The align
, border
, frame
, summary
, rules
, and width
,
IDL attributes of the table
element must reflect the respective content
attributes of the same name.
The bgColor
IDL attribute of the table
element must reflect the element’s bgcolor
content attribute.
The cellPadding
IDL attribute of the table
element must reflect the element’s cellpadding
content attribute.
The cellSpacing
IDL attribute of the table
element must reflect the element’s cellspacing
content attribute.
partial interface HTMLTableSectionElement { attribute DOMString align; attribute DOMString ch; attribute DOMString chOff; attribute DOMString vAlign; };
The align
IDL attribute of the tbody
, thead
, and tfoot
elements must reflect the content attribute of the same
name.
The ch
IDL attribute of the tbody
, thead
, and tfoot
elements must reflect the elements' char
content attributes.
The chOff
IDL attribute of the tbody
, thead
, and tfoot
elements must reflect the elements' charoff
content attributes.
The vAlign
IDL attribute of the tbody
, thead
, and tfoot
element must reflect the elements' valign
content attributes.
partial interface HTMLTableCellElement { attribute DOMString align; attribute DOMString axis; attribute DOMString height; attribute DOMString width; attribute DOMString ch; attribute DOMString chOff; attribute boolean noWrap; attribute DOMString vAlign; [TreatNullAs=EmptyString] attribute DOMString bgColor; };
The align
, axis
, height
,
and width
IDL attributes of the td
and th
elements must reflect the respective content attributes of the same name.
The ch
IDL attribute of the td
and th
elements must reflect the elements' char
content attributes.
The chOff
IDL attribute of the td
and th
elements must reflect the elements' charoff
content attributes.
The noWrap
IDL attribute of the td
and th
elements must reflect the elements' nowrap
content
attributes.
The vAlign
IDL attribute of the td
and th
element must reflect the elements' valign
content
attributes.
The bgColor
IDL attribute of the td
and th
elements must reflect the elements' bgcolor
content
attributes.
partial interface HTMLTableDataCellElement { attribute DOMString abbr; };
The abbr
IDL attribute of the td
element must reflect the respective content attributes of the same name.
partial interface HTMLTableRowElement { attribute DOMString align; attribute DOMString ch; attribute DOMString chOff; attribute DOMString vAlign; [TreatNullAs=EmptyString] attribute DOMString bgColor; };
The align
IDL attribute of the tr
element must reflect the content attribute of the same name.
The ch
IDL attribute of the tr
element must reflect the element’s char
content attribute.
The chOff
IDL attribute of the tr
element must reflect the element’s charoff
content attribute.
The vAlign
IDL attribute of the tr
element must reflect the element’s valign
content attribute.
The bgColor
IDL attribute of the tr
element must reflect the element’s bgcolor
content attribute.
partial interface HTMLUListElement { attribute boolean compact; attribute DOMString type; };
The compact
and type
IDL attributes of the ul
element must reflect the respective content attributes of the
same name.
User agents must treat xmp
elements in a manner equivalent to pre
elements in terms of
semantics and for purposes of rendering. (The parser has special behavior for this element though.)
The blink
, bgsound
, isindex
, multicol
, nextid
, and spacer
elements must
use the HTMLUnknownElement
interface.
partial interface Document { [TreatNullAs=EmptyString] attribute DOMString fgColor; [TreatNullAs=EmptyString] attribute DOMString linkColor; [TreatNullAs=EmptyString] attribute DOMString vlinkColor; [TreatNullAs=EmptyString] attribute DOMString alinkColor; [TreatNullAs=EmptyString] attribute DOMString bgColor; [SameObject] readonly attribute HTMLCollection anchors; [SameObject] readonly attribute HTMLCollection applets; void clear(); void captureEvents(); void releaseEvents(); [SameObject] readonly attribute HTMLAllCollection all; };
The attributes of the Document
object listed in the first column of the following table must reflect the content attribute on the body
element with the name given in the
corresponding cell in the second column on the same row, if the body
element is a body
element (as opposed to a frameset
element). When there is no body
element or if it is a frameset
element, the attributes must instead return the empty string on getting and do
nothing on setting.
IDL attribute | Content attribute |
---|---|
fgColor
| text
|
linkColor
| link
|
vlinkColor
| vlink
|
alinkColor
| alink
|
bgColor
| bgcolor
|
The anchors
attribute must return an HTMLCollection
rooted at the Document
node, whose filter matches only a
elements with name
attributes.
The applets
attribute must return an HTMLCollection
rooted at the Document
node, whose filter matches only applet
elements.
The clear()
, captureEvents()
, and releaseEvents()
methods must do nothing.
The all
attribute must return an HTMLAllCollection
rooted at the Document
node, whose filter matches all elements.
The object returned for all
has several unusual behaviors:
-
The user agent must act as if the ToBoolean() operator in JavaScript converts the object returned for
all
to the false value. -
The user agent must act as if, for the purposes of the
==
and!=
operators in JavaScript, the object returned forall
compares as equal to theundefined
andnull
values. (Comparisons using the===
operator, and comparisons to other values such as strings or objects, are unaffected.) -
The user agent must act such that the
typeof
operator in JavaScript returns the stringundefined
when applied to the object returned forall
.
These requirements are a willful violation of the JavaScript specification current at the
time of writing (ECMAScript edition 6). The JavaScript specification requires that the
ToBoolean() operator convert all objects to the true value, and does not have provisions for
objects acting as if they were undefined
for the purposes of certain operators.
This violation is motivated by a desire for compatibility with two classes of legacy content:
one that uses the presence of document.all
as a way to detect legacy user agents,
and one that only supports those legacy user agents and uses the document.all
object without testing for its presence first. [ECMA-262]
partial interface Window { void captureEvents(); void releaseEvents(); [Replaceable, SameObject] readonly attribute External external; };
The captureEvents()
and releaseEvents()
methods must do nothing.
The external
attribute of the Window
interface
must return an instance of the External
interface:
[NoInterfaceObject] interface External { void AddSearchProvider(); void IsSearchProviderInstalled(); };
The AddSearchProvider()
and IsSearchProviderInstalled()
methods
must do nothing.
12. IANA considerations
12.1. text/html
This registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
-
Type name:
-
text
-
Subtype name:
-
html
-
Required parameters:
-
No required parameters
-
Optional parameters:
-
-
charset
-
The
charset
parameter may be provided to specify the document’s character encoding, overriding any character encoding declarations in the document other than a Byte Order Mark (BOM). The parameter’s value must be one of the labels of the character encoding used to serialize the file. [ENCODING]
-
-
Encoding considerations:
-
8bit (see the section on character encoding declarations)
-
Security considerations:
-
Entire novels have been written about the security considerations that apply to HTML documents. Many are listed in this document, to which the reader is referred for more details. Some general concerns bear mentioning here, however:
HTML is scripted language, and has a large number of APIs (some of which are described in this document). Script can expose the user to potential risks of information leakage, credential leakage, cross-site scripting attacks, cross-site request forgeries, and a host of other problems. While the designs in this specification are intended to be safe if implemented correctly, a full implementation is a massive undertaking and, as with any software, user agents are likely to have security bugs.
Even without scripting, there are specific features in HTML which, for historical reasons, are required for broad compatibility with legacy content but that expose the user to unfortunate security problems. In particular, the
img
element can be used in conjunction with some other features as a way to effect a port scan from the user’s location on the Internet. This can expose local network topologies that the attacker would otherwise not be able to determine.HTML relies on a compartmentalization scheme sometimes known as the same-origin policy. An origin in most cases consists of all the pages served from the same host, on the same port, using the same protocol.
It is critical, therefore, to ensure that any untrusted content that forms part of a site be hosted on a different origin than any sensitive content on that site. Untrusted content can easily spoof any other page on the same origin, read data from that origin, cause scripts in that origin to execute, submit forms to and from that origin even if they are protected from cross-site request forgery attacks by unique tokens, and make use of any third-party resources exposed to or rights granted to that origin.
-
Interoperability considerations:
-
Rules for processing both conforming and non-conforming content are defined in this specification.
-
Published specification:
-
This document is the relevant specification. Labeling a resource with the
text/html
type asserts that the resource is an HTML document using the HTML syntax. -
Applications that use this media type:
-
Web browsers, tools for processing Web content, HTML authoring tools, search engines, validators.
-
Additional information:
-
-
Magic number(s):
-
No sequence of bytes can uniquely identify an HTML document. More information on detecting HTML documents is available in the MIME Sniffing specification. [MIMESNIFF]
-
File extension(s):
-
"
html
" and "htm
" are commonly, but certainly not exclusively, used as the extension for HTML documents. -
Macintosh file type code(s):
-
TEXT
-
-
Person & email address to contact for further information:
-
Ian Hickson <ian@hixie.ch>
-
Intended usage:
-
Common
-
Restrictions on usage:
-
No restrictions apply.
-
Author:
-
Ian Hickson <ian@hixie.ch>
-
Change controller:
-
W3C
Fragment identifiers used with text/html
resources either refer to the indicated part of the document or provide state information for in-page scripts.
12.2. multipart/x-mixed-replace
This registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
-
Type name:
-
multipart
-
Subtype name:
-
x-mixed-replace
-
Required parameters:
-
-
boundary
(defined in RFC2046) [RFC2046]
-
-
Optional parameters:
-
No optional parameters.
-
Encoding considerations:
-
binary
-
Security considerations:
-
Subresources of a
multipart/x-mixed-replace
resource can be of any type, including types with non-trivial security implications such astext/html
. -
Interoperability considerations:
-
None.
-
Published specification:
-
This specification describes processing rules for Web browsers. Conformance requirements for generating resources with this type are the same as for
multipart/mixed
. [RFC2046] -
Applications that use this media type:
-
This type is intended to be used in resources generated by Web servers, for consumption by Web browsers.
-
Additional information:
-
-
Magic number(s):
-
No sequence of bytes can uniquely identify a
multipart/x-mixed-replace
resource. -
File extension(s):
-
No specific file extensions are recommended for this type.
-
Macintosh file type code(s):
-
No specific Macintosh file type codes are recommended for this type.
-
-
Person & email address to contact for further information:
-
Ian Hickson <ian@hixie.ch>
-
Intended usage:
-
Common
-
Restrictions on usage:
-
No restrictions apply.
-
Author:
-
Ian Hickson <ian@hixie.ch>
-
Change controller:
-
W3C
Fragment identifiers used with multipart/x-mixed-replace
resources apply to each
body part as defined by the type used by that body part.
12.3. application/xhtml+xml
This registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
-
Type name:
-
application
-
Subtype name:
-
xhtml+xml
-
Required parameters:
-
Same as for
application/xml
[RFC7303] -
Optional parameters:
-
Same as for
application/xml
[RFC7303] -
Encoding considerations:
-
Same as for
application/xml
[RFC7303] -
Security considerations:
-
Same as for
application/xml
[RFC7303] -
Interoperability considerations:
-
Same as for
application/xml
[RFC7303] -
Published specification:
-
Labeling a resource with the
application/xhtml+xml
type asserts that the resource is an XML document that likely has a root element from the HTML namespace. Thus, the relevant specifications are the XML specification, the Namespaces in XML specification, and this specification. [XML] [XPTR-XMLNS] -
Applications that use this media type:
-
Same as for
application/xml
[RFC7303] -
Additional information:
-
-
Magic number(s):
-
Same as for
application/xml
[RFC7303] -
File extension(s):
-
"
xhtml
" and "xht
" are sometimes used as extensions for XML resources that have a root element from the HTML namespace. -
Macintosh file type code(s):
-
TEXT
-
-
Person & email address to contact for further information:
-
Ian Hickson <ian@hixie.ch>
-
Intended usage:
-
Common
-
Restrictions on usage:
-
No restrictions apply.
-
Author:
-
Ian Hickson <ian@hixie.ch>
-
Change controller:
-
W3C
Fragment identifiers used with application/xhtml+xml
resources have the same
semantics as with any XML MIME type. [RFC7303]
12.4. web+
scheme prefix
This section describes a convention for use with the IANA URI scheme registry. It does not itself register a specific scheme. [RFC7595]
-
Scheme name:
-
Schemes starting with the four characters "
web+
" followed by one or more letters in the rangea
-z
. -
Status:
-
Permanent
-
Scheme syntax:
-
Scheme-specific.
-
Scheme semantics:
-
Scheme-specific.
-
Encoding considerations:
-
All "
web+
" schemes should use UTF-8 encodings where relevant. -
Applications/protocols that use this scheme name:
-
Scheme-specific.
-
Interoperability considerations:
-
The scheme is expected to be used in the context of Web applications.
-
Security considerations:
-
Any Web page is able to register a handler for all "
web+
" schemes. As such, these schemes must not be used for features intended to be core platform features (e.g., network transfer protocols like HTTP or FTP). Similarly, such schemes must not store confidential information in their URLs, such as usernames, passwords, personal information, or confidential project names. -
Contact:
-
Ian Hickson <ian@hixie.ch>
-
Change controller:
-
Ian Hickson <ian@hixie.ch>
-
References:
-
Custom scheme and content handlers, HTML Continually Updated Specification: https://html.spec.whatwg.org/#custom-handlers
Index
Terms defined by this specification
- "", in §4.7.14
- 1, in §4.4.5
-
2d
- context for canvas, in §4.12.4
- definition of, in §4.12.4
-
a
- attr-value for ol/type, in §4.4.5
- (element), in §4.5.1
-
abbr
- (element), in §4.5.9
- element-attr for th, in §4.9.10
- attribute for HTMLTableHeaderCellElement, in §4.9.10
- element-attr for td, in §11.2
- attribute for HTMLTableDataCellElement, in §11.3.5
-
abort
- event for media, in §4.7.14.15
- event for global, in §Unnumbered section
- abort(), in §11.3.4.8
- abort a document, in §6.7.12
- abort a parser, in §8.2.6
- abort a running script, in §7.1.3.6
- aborted, in §6.7.12
- aborted prematurely, in §7.1.3.6
- aborted the running script, in §7.1.3.6
- aborting a document, in §6.7.12
- aborting the running script, in §7.1.3.6
- abort that parser, in §8.2.6
- abort the document, in §6.7.12
- abort the image request, in §4.7.5
- abort the parser, in §8.2.6
- abort the script, in §7.1.3.6
- about:, in §2.2.2
- about:blank, in §2.2.2
- about:legacy-compat, in §2.5.1
- about:srcdoc, in §2.5.1
- about-to-be-notified rejected promises list, in §7.1.3.1
- a browsing context is discarded, in §6.3.4
-
accept
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.1.17
- element-attr for form, in §11.2
- acceptCharset, in §4.10.3
- accept-charset, in §4.10.3
- Access Key, in §4.11.6.1
- accessKey, in §5.5.3
- accesskey, in §5.5.2
- acknowledged, in §8.2.4
- acknowledge the token’s self-closing flag, in §8.2.4
- acronym, in §11.2
- Action, in §4.11.6.1
-
action
- element-attr for form, in §4.10.19.6
- definition of, in §4.10.19.6
- attribute for HTMLFormElement, in §4.10.19.6
- activation behavior, in §5.3
- :active, in §4.15.2
- activeCues, in §4.7.14.11.5
- active document, in §6.1
- activeElement, in §5.4.6
- active flag, in §4.7.14.11.1
- active flag was set when the script started, in §4.7.14.11.5
- active frame element, in §11.3.3
- active parser, in §3.1.2
- active range, in §5.6.4
- active sandboxing flag set, in §6.5
- actually disabled, in §4.14
- actual value, in §4.10.15
- add(), in §5.7.3.1
- addCue(cue), in §4.7.14.11.5
- add(data), in §5.7.3.1
- add(data, type), in §5.7.3.1
-
add(element)
- method for HTMLOptionsCollection, in §2.7.2.3
- method for HTMLSelectElement, in §4.10.7
-
add(element, before)
- method for HTMLOptionsCollection, in §2.7.2.3
- method for HTMLSelectElement, in §4.10.7
- additional allowed character, in §8.2.4.69
-
address
- definition of, in §3.1
- (element), in §4.3.9
- AddSearchProvider(), in §11.3.5
- addTextTrack(kind, label, language), in §4.7.14.11.5
- addtrack, in §4.7.14.15
- adjusted current node, in §8.2.3.2
- adjust foreign attributes, in §8.2.5.1
- adjust MathML attributes, in §8.2.5.1
- adjust SVG attributes, in §8.2.5.1
- administrative level, in §4.10.19.8.1
- adoption agency algorithm, in §8.2.5.4.7
- a drag data item kind, in §5.7.2
- a drag data item type string, in §5.7.2
- advance, in §4.9.12.1
- advanced to the next child of the table, in §4.9.12.1
- advisory information, in §3.2.5.2
- a fallback entry, in §11.3.4
- affected by a base URL change, in §2.2.2
- after after body, in §8.2.5.4.22
- after after frameset, in §8.2.5.4.23
- after body, in §8.2.5.4.19
- after frameset, in §8.2.5.4.21
- after head, in §8.2.5.4.6
- afterprint, in §Unnumbered section
- afterscriptexecute, in §Unnumbered section
- a known definite encoding, in §8.2.2.1
- a label, in §4.7.14.11.1
- a language, in §4.7.14.11.1
- alert(), in §7.5.1
- alert(message), in §7.5.1
- algorithm for assigning header cells, in §4.9.12.2
- algorithm for ending a row group, in §4.9.12.1
- algorithm for extracting a character encoding from a meta element, in §2.6.5
- algorithm for growing downward-growing cells, in §4.9.12.1
- algorithm for processing row groups, in §4.9.12.1
- algorithm for processing rows, in §4.9.12.1
- algorithm to convert a Date object to a string, in §4.10.5
- algorithm to convert a number to a string, in §4.10.5
- algorithm to convert a string to a Date object, in §4.10.5
- algorithm to convert a string to a number, in §4.10.5
-
align
- element-attr for caption, in §11.2
- element-attr for col, in §11.2
- element-attr for div, in §11.2
- element-attr for embed, in §11.2
- element-attr for hr, in §11.2
- element-attr for headings, in §11.2
- element-attr for iframe, in §11.2
- element-attr for input, in §11.2
- element-attr for img, in §11.2
- element-attr for legend, in §11.2
- element-attr for object, in §11.2
- element-attr for p, in §11.2
- element-attr for table, in §11.2
- element-attr for tbody, thead, tfoot, tablesection, in §11.2
- element-attr for td, th, tablecells, in §11.2
- element-attr for tr, in §11.2
- attribute for HTMLAppletElement, in §11.3.1
- attribute for HTMLTableCaptionElement, in §11.3.5
- attribute for HTMLTableColElement, in §11.3.5
- attribute for HTMLDivElement, in §11.3.5
- attribute for HTMLEmbedElement, in §11.3.5
- attribute for HTMLHeadingElement, in §11.3.5
- attribute for HTMLHRElement, in §11.3.5
- attribute for HTMLIFrameElement, in §11.3.5
- attribute for HTMLImageElement, in §11.3.5
- attribute for HTMLInputElement, in §11.3.5
- attribute for HTMLLegendElement, in §11.3.5
- attribute for HTMLObjectElement, in §11.3.5
- attribute for HTMLParagraphElement, in §11.3.5
- attribute for HTMLTableElement, in §11.3.5
- attribute for HTMLTableSectionElement, in §11.3.5
- attribute for HTMLTableCellElement, in §11.3.5
- attribute for HTMLTableRowElement, in §11.3.5
- align descendants, in §10.2
- alink, in §11.2
- aLink, in §11.3.5
- alinkColor, in §11.3.5
- a list of zero or more cues, in §4.7.14.11.1
-
all
- value for effectAllowed, in §5.7.3
- attribute for Document, in §11.3.5
- "all"-named elements, in §2.7.2.1
- allowed keywords and their meanings, in §4.8.6
- allowed to navigate, in §6.1.3
- allowed to show a popup, in §6.1.5
- allowed value step, in §4.10.5.3.8
- allow-forms, in §6.5
- allowfullscreen, in §4.7.6
- allowFullscreen, in §4.7.6
- allow-modals, in §6.5
- allow-pointer-lock, in §6.5
- allow-popups, in §6.5
- allow-popups-to-escape-sandbox, in §6.5
- allow-same-origin, in §6.5
- allow-scripts, in §6.5
- allow-top-navigation, in §6.5
- allowtransparency, in §11.2
- alphanumeric ASCII characters, in §2.4.1
- "already started", in §4.12.1.1
-
alt
- element-attr for img, in §4.7.5
- attribute for HTMLImageElement, in §4.7.5
- element-attr for area, in §4.7.16
- attribute for HTMLAreaElement, in §4.7.16
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.1.19
- attribute for HTMLAppletElement, in §11.3.1
-
alternate
- attr-value for link/type, in §4.8.6.1
- attr-value for marquee/behavior, in §11.3.2
- state for marquee/behavior, in §11.3.2
- alternative, in §4.7.14.10.1
- ambiguous ampersand, in §8.1.4
- a mode, in §4.7.14.11.1
- an alternative stylesheet, in §4.8.6.10
- ancestor, in §6.1.1
- ancestor browsing context, in §6.1.1
- ancestorOrigins, in §6.6.4
- ancestor origins array, in §6.6.4
- anchors, in §11.3.5
- an end time, in §4.7.14.11.1
- An entry with persisted user state, in §6.6.1
- a new date object, in §2.2.2
- a new start for session storage, in §6.1.5
- an explicit entry, in §11.3.4
- an identifier, in §4.7.14.11.1
- an iframe srcdoc documents, in §4.7.6
- animation frame callback identifier, in §7.8
- an in-band metadata track dispatch type, in §4.7.14.11.1
- an indicated part of the document, in §6.7.9
- annotates, in §4.8.1
- annotation pairing, in §4.5.10
- anonymous, in §2.6.6
- Anonymous, in §2.6.6
- an overridden reload, in §3.1
- An unstyled document view, in §10.9
- any, in §4.8.6.5
- API base URL, in §7.1.3.1
- APIs, in §4.10.5.4
- API URL character encoding, in §7.1.3.1
- API value, in §4.10.11
- a plausible language, in §7.6.1.2
- appCodeName, in §7.6.1.1
- applet, in §11.3.1
- applets, in §11.3.5
- applicable specification, in §2.2.3
- application cache, in §11.3.4
- ApplicationCache, in §11.3.4.8
-
applicationCache
- attribute for Window, in §11.3.4.8
- attribute for SharedWorkerGlobalScope, in §11.3.4.8
- application cache download process, in §11.3.4.2
- application cache group, in §11.3.4
- application cache manifest, in §11.3.4
- application cache mode, in §11.3.4
- application cache selection, in §11.3.4.3
- application cache selection algorithm, in §11.3.4.3
- application-name, in §4.2.5.1
- application/x-www-form-urlencoded, in §4.10.19.6
- application/x-www-form-urlencoded encoding algorithm, in §4.10.22.6
- apply, in §4.10.5
- appName, in §7.6.1.1
- appropriate end tag token, in §8.2.4
- appropriate form encoding algorithm, in §4.10.22.3
- appropriate place for inserting a node, in §8.2.5.1
- appropriate template contents owner document, in §4.12.3
- appVersion, in §7.6.1.1
-
archive
- element-attr for object, in §11.2
- attribute for HTMLAppletElement, in §11.3.1
- attribute for HTMLObjectElement, in §11.3.5
- area, in §4.7.16
- a readiness state, in §4.7.14.11.1
- areas, in §4.7.15
- a registered handler, in §7.6.1.3
- aria-*, in §2.2.2
- aria-checked, in §2.2.2
- aria-describedby, in §2.2.2
- aria-disabled, in §2.2.2
- aria-expanded, in §2.2.2
- aria-hidden, in §2.2.2
- aria-invalid, in §2.2.2
- aria-label, in §2.2.2
- aria-level, in §2.2.2
- aria-multiline, in §2.2.2
- aria-multiselectable, in §2.2.2
- aria-owns, in §2.2.2
- aria-readonly, in §2.2.2
- aria-required, in §2.2.2
- aria-selected, in §2.2.2
- aria-sort, in §2.2.2
- aria-valuemax, in §2.2.2
- aria-valuemin, in §2.2.2
- aria-valuenow, in §2.2.2
- art directed, in §4.7.1
- art direction, in §4.7.1
- article, in §4.3.2
- as a download, in §4.8.5
- ASCII case-insensitive, in §2.3
- ASCII-compatible encoding, in §2.1.6
- ASCII digits, in §2.4.1
- ASCII hex digits, in §2.4.1
- ASCII serialization of an origin, in §6.4
- a serialization of the bitmap as a file, in §4.12.4.2
- a serialization of the canvas element’s bitmap as a file, in §4.12.4.2
- as hints for the rendering, in §10.2
- aside, in §4.3.5
- ask for a reset, in §4.10.7
- asks for a reset, in §4.10.7
- as part of an attribute, in §8.2.4.41
- assign(), in §6.6.4
- assigned access key, in §5.5.3
- assigned context menu, in §4.11.5.2
- assigned media provider object, in §4.7.14.2
- assign(url), in §6.6.4
- associated, in §4.10.18.3
- associated content-type headers, in §2.6.4
- associated content-type metadata, in §2.6.4
- associated inert template document, in §4.12.3
- associate section, in §4.3.10.1
- a start time, in §4.7.14.11.1
- as that element in the specific scope, in §8.2.3.2
- a style sheet that is blocking scripts, in §4.2.7
-
async
- element-attr for script, in §4.12.1
- attribute for HTMLScriptElement, in §4.12.1
- atob(atob), in §7.2
- attribute, in §8.1.2.3
- attribute name, in §8.1.2.3
- attribute names, in §8.1.2.3
- attributes, in §8.1.2.3
- attribute serialized name, in §8.3
- Attributes for form submission, in §4.10.19.6
- attribute value, in §8.1.2.3
- attribute values, in §8.1.2.3
- a type change is signalled, in §4.10.5
- A type that the user agent knows it cannot render, in §4.7.14.3
- audio, in §4.7.11
- Audio(src), in §4.7.11
- AudioTrack, in §4.7.14.10.1
- AudioTrack.enabled, in §4.7.14.10.1
- AudioTrack.id, in §4.7.14.10.1
- AudioTrack.kind, in §4.7.14.10.1
- AudioTrack.label, in §4.7.14.10.1
- AudioTrack.language, in §4.7.14.10.1
- AudioTrackList, in §4.7.14.10.1
- AudioTrackList.getTrackById(id), in §4.7.14.10.1
- AudioTrackList.length, in §4.7.14.10.1
- audioTracks, in §4.7.14.10
-
author
- definition of, in §4.2.5.1
- attr-value for link/type, in §4.8.6.2
- "auto", in §6.6.2
-
auto
- attr-value for global/dir, in §3.2.5.6
- state for dir, in §3.2.5.6
- value for HTMLMediaElement/preload, in §4.7.14.5
- state for scope, in §4.9.10
- value for scrollRestorationMode, in §6.6.1
- enum-value for ScrollRestoration, in §6.6.2
-
autocomplete
- attribute for HTMLFormElement, in §4.10.3
- element-attr for autocompleteelements, form, input, select, textarea, in §4.10.19.8.1
- attribute for HTMLInputElement, HTMLSelectElement, HTMLTextAreaElement, in §4.10.19.8.2
- autofill, in §4.10.19.8
- autofill anchor mantle, in §4.10.19.8.1
- Autofill detail tokens, in §4.10.19.8.1
- autofill expectation mantle, in §4.10.19.8.1
- autofill field, in §4.10.19.8.1
- autofill field name, in §4.10.19.8.2
- autofill hint set, in §4.10.19.8.2
- autofill mechanism, in §4.10.19.8
- autofill scope, in §4.10.19.8.2
- autofills form controls, in §4.10.19.8.2
- autofocus
- Automatic, in §4.7.14.5
-
autoplay
- element-attr for media, in §4.7.14.7
- attribute for HTMLMediaElement, in §4.7.14.7
- autoplaying flag, in §4.7.14.5
- auxiliary browsing context, in §6.1.2
- auxiliary browsing contexts, in §6.1.2
- Available, in §4.7.5
-
available
- state for img, in §4.7.5
- definition of, in §4.10.5.1.19
- await a stable state, in §7.1.4.2
- a WebSocket message has been received, in §2.2.2
-
axis
- element-attr for td, in §11.2
- attribute for HTMLTableCellElement, in §11.3.5
- b, in §4.5.23
- back(), in §6.6.2
- background
- badInput, in §4.10.21.3
- BarProp, in §6.3.6
- barred from constraint validation, in §4.10.21.1
- barring it from constraint validation, in §4.10.21.1
- base, in §4.2.3
- basefont, in §11.2
- base URL change steps, in §2.2.2
- bdi, in §4.5.26
- bdo, in §4.5.27
- before head, in §8.2.5.4.3
- before html, in §8.2.5.4.2
- beforeprint, in §Unnumbered section
- beforescriptexecute, in §Unnumbered section
- beforeunload, in §Unnumbered section
- BeforeUnloadEvent, in §6.7.11.1
-
behavior
- element-attr for marquee, in §11.3.2
- attribute for HTMLMarqueeElement, in §11.3.2
- being activated, in §4.15.2
- being actively pointed at, in §4.15.2
- being rendered, in §10.1
- being unloaded, in §6.7.11
- being used as relevant canvas fallback content, in §4.12.4
- best floating-point number, in §2.4.4.3
-
bgcolor
- element-attr for body, in §11.2
- element-attr for table, in §11.2
- element-attr for td, th, tablecells, in §11.2
- element-attr for tr, in §11.2
-
bgColor
- attribute for HTMLMarqueeElement, in §11.3.2
- attribute for HTMLBodyElement, in §11.3.5
- attribute for HTMLTableElement, in §11.3.5
- attribute for HTMLTableCellElement, in §11.3.5
- attribute for HTMLTableRowElement, in §11.3.5
- attribute for Document, in §11.3.5
- bgsound, in §11.2
- bidirectional-algorithm formatting character ranges, in §3.2.6.1
- big, in §11.2
- Big5, in §8.2.2.3
- billing, in §4.10.19.8.1
- blank, in §10.3.10
- blink, in §11.2
- blob:, in §2.2.2
- blocked by a modal dialog, in §5.2
- blocked by the modal dialog, in §5.2
- blocked media element, in §4.7.14.8
- blocked-on-parser, in §4.7.14.11.1
- blockquote, in §4.4.4
- blur, in §Unnumbered section
- blur(), in §5.4.6
-
body
- attribute for Document, in §3.1.3
- (element), in §4.3.1
- bookmark, in §4.8.6.3
- boolean attribute, in §2.4.2
- boolean attributes, in §2.4.2
-
border
- element-attr for HTMLTableElement, in §4.9.1
- element-attr for input, in §11.2
- element-attr for img, in §11.2
- element-attr for object, in §11.2
- element-attr for table, in §11.2
- attribute for HTMLImageElement, in §11.3.5
- attribute for HTMLObjectElement, in §11.3.5
- attribute for HTMLTableElement, in §11.3.5
- bordercolor, in §11.2
- bottommargin, in §11.2
- bounce, in §11.3.2
- br, in §4.5.29
- broken, in §4.7.5
- Broken, in §4.7.5
- browsing context, in §6.1
- browsing context container, in §6.1.1
- browsing context name, in §6.1.5
- browsing contexts, in §6.1
- browsing context scope origin, in §6.1.3
- btoa(btoa), in §7.2
- buffered, in §4.7.14.5
- build a menu construct, in §4.11.3
- build and show, in §4.11.3
- build and show a menu, in §4.11.3
-
Button
- element-state for input, in §4.10.5.1.21
- element-state for button/type, in §4.10.6
-
button
- attr-value for input/type, in §4.10.5
- (element), in §4.10.6
- attr-value for button/type, in §4.10.6
- buttons, in §4.10.2
- cache attempt, in §11.3.4.2
- cache failure steps, in §11.3.4.2
- cache host, in §11.3.4
- cache mode flag, in §11.3.4
- cache selection, in §11.3.4.3
- calling scripts, in §7.1.3.4
- can be focused, in §5.4.3
- cancelAnimationFrame(), in §7.8
- cancelAnimationFrame(handle), in §7.8
- canceled activation steps, in §5.3
- candidate for constraint validation, in §4.10.21.1
- candidates for constraint validation, in §4.10.21.1
- canplay, in §4.7.14.15
- canplaythrough, in §4.7.14.15
- canPlayType(type), in §4.7.14.3
- canvas, in §4.12.4
- canvas blob serialization task source, in §4.12.4
- canvas context mode, in §4.12.4
-
caption
- attribute for HTMLTableElement, in §4.9.1
- (element), in §4.9.2
-
captions
- attr-value for track/kind, in §4.7.13
- attr-value for commonTrack/kind, in §4.7.14.10.1
- definition of, in §4.7.14.11.1
- enum-value for TextTrackKind, in §4.7.14.11.5
- Captions, in §4.7.13
- "captions", in §4.7.14.11.5
-
captureEvents()
- method for Document, in §11.3.5
- method for Window, in §11.3.5
- case-sensitive, in §2.3
- Categories, in §3.2.3
- causes the opener attribute to remain null, in §6.1.5
- CDATA sections, in §8.1.5
- cell, in §4.9.12
- cellIndex, in §4.9.11
- cellpadding, in §11.2
- cellPadding, in §11.3.5
-
cells
- attribute for HTMLTableRowElement, in §4.9.8
- definition of, in §4.9.12
- cellspacing, in §11.2
- cellSpacing, in §11.3.5
- center, in §11.2
-
ch
- attribute for HTMLTableColElement, in §11.3.5
- attribute for HTMLTableSectionElement, in §11.3.5
- attribute for HTMLTableCellElement, in §11.3.5
- attribute for HTMLTableRowElement, in §11.3.5
-
challenge
- element-attr for keygen, in §4.10.12
- attribute for HTMLKeygenElement, in §4.10.12
-
change
- definition of, in §2.1.3
- event for MediaList, in §4.7.14.15
- event for input, in §4.10.5.5
- event for global, in §Unnumbered section
- change the encoding, in §8.2.2.4
- "chapters", in §4.7.14.11.5
- Chapters, in §4.7.13
-
chapters
- attr-value for track/kind, in §4.7.13
- definition of, in §4.7.14.11.1
- enum-value for TextTrackKind, in §4.7.14.11.5
-
char
- element-attr for col, in §11.2
- element-attr for tbody, thead, tfoot, tablesection, in §11.2
- element-attr for td, th, tablecells, in §11.2
- element-attr for tr, in §11.2
- character, in §2.1.6
- character encoding, in §2.1.6
- character encoding declaration, in §4.2.5.5
- character height, in §4.10.11
- character references, in §8.1.4
- character width, in §4.10.11
-
charoff
- element-attr for col, in §11.2
- element-attr for tbody, thead, tfoot, tablesection, in §11.2
- element-attr for td, th, tablecells, in §11.2
- element-attr for tr, in §11.2
- _charset_, in §4.10.19.1
-
charset
- element-attr for meta, in §4.2.5
- element-attr for script, in §4.12.1
- attribute for HTMLScriptElement, in §4.12.1
- element-attr for a, in §11.2
- element-attr for link, in §11.2
- attribute for HTMLAnchorElement, in §11.3.5
- attribute for HTMLLinkElement, in §11.3.5
-
Checkbox
- element-state for input, in §4.10.5.1.15
- state for menuitem, in §4.11.4
-
checkbox
- attr-value for input/type, in §4.10.5
- attr-value for menuitem/type, in §4.11.4
-
checked
- element-attr for input, in §4.10.5
- attribute for HTMLInputElement, in §4.10.5.4
- element-attr for menuitem, in §4.11.4
- attribute for HTMLMenuItemElement, in §4.11.4
- :checked, in §4.15.2
- checkedness, in §4.10.18.1
- check if we can run script, in §7.1.3.4
- CHECKING, in §11.3.4.8
- checkValidity()
- child browsing context, in §6.1.1
- child browsing context name property set, in §6.3.3
- child browsing contexts, in §6.1.1
- child text content, in §2.1.3
-
chOff
- attribute for HTMLTableColElement, in §11.3.5
- attribute for HTMLTableSectionElement, in §11.3.5
- attribute for HTMLTableCellElement, in §11.3.5
- attribute for HTMLTableRowElement, in §11.3.5
- circ, in §4.7.16
- circle, in §4.7.16
- circle state, in §4.7.16
- Circle state, in §4.7.16
-
cite
- element-attr for blockquote, in §4.4.4
- (element), in §4.5.6
- element-attr for q, in §4.5.7
- element-attr for edits, in §4.6.3
- attribute for HTMLModElement, in §4.6.3
- class, in §3.2.5.7
- classic script, in §7.1.3.1
- classid, in §11.2
- clean up after running script, in §7.1.3.4
-
clear
- element-attr for br, in §11.2
- attribute for HTMLBRElement, in §11.3.5
-
clear()
- method for DataTransferItemList, in §5.7.3.1
- method for Document, in §11.3.5
- clearData(), in §5.7.3
- clearData(format), in §5.7.3
- clearInterval(), in §7.4
- clearInterval(handle), in §7.4
- clear the list of active formatting elements up to the last marker, in §8.2.3.3
- clear the stack back to a table body context, in §8.2.5.4.13
- clear the stack back to a table context, in §8.2.5.4.9
- clear the stack back to a table row context, in §8.2.5.4.14
- clearTimeout(), in §7.4
- clearTimeout(handle), in §7.4
- click(), in §5.3
- Clone, in §2.9.1
- Cloneable objects, in §2.9.1
-
close()
- method for Window, in §6.3.1
- method for Document, in §7.3.2
- close a browsing context, in §6.3.5
- close a p element, in §8.2.5.4.7
- closed, in §6.3.1
- close the cell, in §8.2.5.4.15
- close the WebSocket connection, in §2.2.2
- closing misnested formatting elements, in §8.2.5.4.7
-
code
- (element), in §4.5.17
- attribute for MediaError, in §4.7.14.1
- element-attr for object, in §11.2
- attribute for HTMLAppletElement, in §11.3.1
- attribute for HTMLObjectElement, in §11.3.5
-
codeBase
- attribute for HTMLAppletElement, in §11.3.1
- attribute for HTMLObjectElement, in §11.3.5
- codebase, in §11.2
- codetype, in §11.2
- codeType, in §11.3.5
- code unit, in §2.1.6
- code-unit length, in §2.1.6
-
col
- (element), in §4.9.4
- attr-value for scope, in §4.9.10
-
colgroup
- (element), in §4.9.3
- attr-value for scope, in §4.9.10
- colgroup group, in §4.9.10
- collect a sequence of characters, in §2.4.1
- colno, in §7.1.3.8.2
- Color, in §4.10.5.1.14
-
color
- attr-value for input/type, in §4.10.5
- element-attr for hr, in §11.2
- attribute for HTMLFontElement, in §11.3.5
- attribute for HTMLHRElement, in §11.3.5
-
cols
- element-attr for textarea, in §4.10.11
- attribute for HTMLTextAreaElement, in §4.10.11
- element-attr for frameset, in §11.3.3
- colspan, in §4.9.11
- colSpan, in §4.9.11
-
column
- state for scope, in §4.9.10
- definition of, in §4.9.12
- column group, in §4.9.12
- column group header, in §4.9.12.2
- column groups, in §4.9.12
- column header, in §4.9.12.2
- columns, in §4.9.12
- Command, in §4.11.4
-
command
- attr-value for menuitem/type, in §4.11.4
- dfn for menuitem, in §4.11.6.1
- comment, in §8.1.6
- commentary, in §4.7.14.10.1
- comments, in §8.1.6
- commit an automatic annotation, in §4.5.13
- commit an automatic base, in §4.5.10
- commit a ruby segment, in §4.5.10
- commit current annotations, in §4.5.10
- commit the base range, in §4.5.10
-
compact
- element-attr for dl, in §11.2
- element-attr for menu, in §11.2
- element-attr for ol, in §11.2
- element-attr for ul, in §11.2
- attribute for HTMLDirectoryElement, in §11.3.5
- attribute for HTMLDListElement, in §11.3.5
- attribute for HTMLMenuElement, in §11.3.5
- attribute for HTMLOListElement, in §11.3.5
- attribute for HTMLUListElement, in §11.3.5
- comparing origins, in §6.4
- compatibility caseless, in §2.3
- compiled pattern regular expression, in §4.10.5.3.6
- "complete", in §3.1.1
-
complete
- enum-value for DocumentReadyState, in §3.1.1
- attribute for HTMLImageElement, in §4.7.5
- Completely available, in §4.7.5
- completely available, in §4.7.5
- completely loaded, in §8.2.6
- completeness flag, in §11.3.4
- compound microtasks, in §7.1.4.2
- compound microtask subtask, in §7.1.4.2
- computed MIME type, in §2.6.4
- computed type of a resource, in §2.6.4
- computed type of the resource, in §2.6.4
- conent category, in §3.2.4.2
- confidence, in §8.2.2
- confirm(), in §7.5.1
- confirm(message), in §7.5.1
- conforming document, in §2.2.1
- conforming documents, in §2.2.1
- constraint validation API, in §4.10.21.3
- Constructing the form data set, in §4.10.22.4
- construct the form data set, in §4.10.22.4
- consume a character reference, in §8.2.4.69
- consumed, in §8.2.2.5
- container frame element, in §10.3.2
-
content
- element-attr for meta, in §4.2.5
- attribute for HTMLMetaElement, in §4.2.5
- attribute for HTMLTemplateElement, in §4.12.3
- content attribute, in §3.2.3
- content attributes, in §3.2.3
- content categories, in §3.2.4.2
-
contentDocument
- attribute for HTMLIFrameElement, in §4.7.6
- attribute for HTMLFrameElement, in §11.3.3
- contentEditable, in §5.6.1
- contenteditable, in §5.6.1
- content-language, in §4.2.5.3
- Content model, in §3.2.3
- Content security policy state, in §4.2.5.3
-
content-type
- definition of, in §2.6.4
- state for http-equiv, in §4.2.5.3
- content-type metadata, in §2.6.4
-
contentWindow
- attribute for HTMLIFrameElement, in §4.7.6
- attribute for HTMLFrameElement, in §11.3.3
-
context
- attr-value for menu/type, in §4.11.3
- definition of, in §8.4
- contextMenu, in §4.11.5.2
- context menu, in §4.11.5
-
contextmenu
- element-attr for global, in §4.11.5.1
- event for global, in §Unnumbered section
- context mode, in §4.12.4
- Contexts in which this element can be used, in §3.2.3
- control, in §4.10.4
- control characters, in §2.4.1
- control group, in §5.4.2
- control group owner, in §5.4.2
- control group owner object, in §5.4.2
- control group owner objects, in §5.4.2
-
controls
- attribute for Document, in §3.2.1
- element-attr for mediaelements, video, audio, in §4.7.14.12
- attribute for HTMLMediaElement, in §4.7.14.12
- control’s data, in §4.10.19.8.2
- controls in the user interface that is exposed to the user, in §4.7.14.12
- convert a list of dimensions to a list of pixel values, in §10.6
- converting a character width to pixels, in §10.5.4
- Converting a string to ASCII lowercase, in §2.3
- Converting a string to ASCII uppercase, in §2.3
- cookie, in §3.1.2
- cookie-averse, in §3.1.2
- cookieEnabled, in §7.6.1.4
- cookies set during the server’s opening handshake, in §2.2.2
- cookie-string, in §2.2.2
- coordinate, in §4.10.5.1.19
-
coords
- element-attr for area, in §4.7.16
- attribute for HTMLAreaElement, in §4.7.16
- element-attr for a, in §11.2
- attribute for HTMLAnchorElement, in §11.3.5
-
copy
- value for dropEffect, in §5.7.3
- value for effectAllowed, in §5.7.3
- value for drag, in §5.7.5
- definition of, in §5.7.8
- event for global, in §Unnumbered section
- copyLink, in §5.7.3
- copyMove, in §5.7.3
- cors-same-origin, in §6.4
- CORS settings attribute, in §2.6.6
- create a classic script, in §7.1.3.3
- create a drag data store, in §5.7.2
- create an element for a token, in §8.2.5.1
- create an element for the token, in §8.2.5.1
- create a new browsing context, in §6.1
- create a potential-CORS request, in §2.6.1
- create a script, in §7.1.3.3
- createCaption(), in §4.9.1
- createImageBitmap(), in §7.7
- createImageBitmap(image), in §7.7
- createImageBitmap(image, sx, sy, sw, sh), in §7.7
- createTBody(), in §4.9.1
- createTFoot(), in §4.9.1
- createTHead(), in §4.9.1
- creating a classic script, in §7.1.3.3
- creating a new browsing context, in §6.1
- creating a potential-cors request, in §2.6.1
- creating scripts, in §7.1.3.3
- creation URL, in §7.1.3.1
- creator base URL, in §6.1
- creator browsing context, in §6.1
- creator origin, in §6.1
- creator URL, in §6.1
- critical subresource, in §2.1.1
- critical subresources, in §2.1.1
- crop bitmap data to the source rectangle, in §7.7
- cropped to the source rectangle, in §7.7
- cross-boundary event parent, in §2.2.2
-
crossorigin
- element-attr for link, in §4.2.4
- element-attr for img, in §4.7.5
- element-attr for media, in §4.7.14.2
- element-attr for script, in §4.12.1
-
crossOrigin
- attribute for HTMLLinkElement, in §4.2.4
- attribute for HTMLImageElement, in §4.7.5
- attribute for HTMLMediaElement, in §4.7.14.2
- attribute for HTMLScriptElement, in §4.12.1
- cross-origin, in §6.4
- CrossOriginFunctionWrapper, in §6.2.3.3.2
- CrossOriginGet, in §6.2.3.4
- CrossOriginGetOwnPropertyHelper, in §6.2.3.3
- CrossOriginOwnPropertyKeys, in §6.2.3.6
- CrossOriginProperties, in §6.2.3.1
- CrossOriginPropertyDescriptor, in §6.2.3.3.1
- CrossOriginPropertyDescriptorMap, in §6.2.2
- CrossOriginSet, in §6.2.3.5
- cross-origin wrapper function, in §6.2.3.3.2
- CSP list, in §3.1.1
- CSS properties, in §2.1
- CSS property, in §2.1
- cue, in §4.7.14.11.1
- cuechange, in §4.7.14.15
-
cues
- definition of, in §4.7.14.11.1
- attribute for TextTrack, in §4.7.14.11.5
- Current, in §7.1.3.5
- current document readiness, in §3.1.2
- current drag operation, in §5.7.5
- current entry, in §6.6.1
- current entry of the joint session history, in §6.6.2
- current global object, in §7.1.3.5.3
- current input character, in §8.2.2.5
- currently focused area of a top-level browsing context, in §5.4.2
- currently focused area of the top-level browsing context, in §5.4.2
- currently relevant menu element, in §4.11.3
- currently running task, in §7.1.4.1
- current node, in §8.2.3.2
- current pixel density, in §4.7.5
- current playback position, in §4.7.14.6
- current position, in §4.7.14.6
- current request, in §4.7.5
- currentScript, in §3.1.3
- current settings object, in §7.1.3.5.3
-
currentSrc
- attribute for HTMLImageElement, in §4.7.5
- attribute for HTMLMediaElement, in §4.7.14.2
- current target element, in §5.7.5
- current template insertion mode, in §8.2.3.1
- currentTime, in §4.7.14.6
- current URL, in §4.7.5
- current value, in §4.10.14
- custom data attribute, in §3.2.5.9
- customError, in §4.10.21.3
- custom validity error message, in §4.10.21.1
- cut, in §Unnumbered section
- data-, in §3.2.5.9
- data:, in §2.2.2
-
data
- (element), in §4.5.15
- element-attr for object, in §4.7.8
- attribute for DataCue, in §4.7.14.11.6
- data-*, in §3.2.5.9
- data block, in §4.12.1
- data blocks, in §4.12.1
- DataCue, in §4.7.14.11.6
- DataCue(startTime, endTime, data), in §4.7.14.11.6
- datafld, in §11.2
- dataformatas, in §11.2
- datalist, in §4.10.8
- datapagesize, in §11.2
- datasrc, in §11.2
- dataTransfer, in §5.7.4
- DataTransfer, in §5.7.3
- DataTransferItem, in §5.7.3.2
- DataTransferItemList, in §5.7.3.1
- data url, in §2.2.2
- data: url, in §2.2.2
-
date
- dfn for dates, in §2.4.5.2
- attr-value for input/type, in §4.10.5
- Date, in §4.10.5.1.7
- date object, in §2.2.2
- dates, in §2.4.5.2
-
datetime
- element-attr for time, in §4.5.16
- element-attr for edits, in §4.6.3
-
dateTime
- attribute for HTMLTimeElement, in §4.5.16
- attribute for HTMLModElement, in §4.6.3
- datetime-local, in §4.10.5
- datetime value, in §4.5.16
- dd, in §4.4.10
- decimal, in §4.4.5
-
declare
- element-attr for object, in §11.2
- attribute for HTMLObjectElement, in §11.3.5
- dedicated media source failure steps, in §4.7.14.5
- Default, in §4.10.19.7
- :default, in §4.15.2
-
default
- element-attr for track, in §4.7.13
- attribute for HTMLTrackElement, in §4.7.13
- attr-value for area/shape, in §4.7.16
- mode for input, in §4.10.5.4
- mode for output, in §4.10.13
- element-attr for menuitem, in §4.11.4
- attribute for HTMLMenuItemElement, in §4.11.4
- default behavior, in §5.6.5
- default button, in §4.10.22.2
- defaultChecked, in §4.10.5
- default commands, in §4.11.3
- default maximum, in §4.10.5.3.7
- default minimum, in §4.10.5.3.7
- defaultMuted, in §4.7.14.12
- default object size, in §2.2.2
- default/on, in §4.10.5.4
- defaultPlaybackRate, in §4.7.14.8
- default playback start position, in §4.7.14.6
- DefaultProperties, in §6.6.4
- defaultSelected, in §4.10.10
- default state, in §4.7.16
- Default state, in §4.7.16
- default step, in §4.10.5.3.8
- default step base, in §4.10.5.3.8
- default-style, in §4.2.5.3
-
default value
- dfn for range, in §4.10.5.1.13
- dfn for output, in §4.10.13
-
defaultValue
- attribute for HTMLInputElement, in §4.10.5
- attribute for HTMLTextAreaElement, in §4.10.11
- attribute for HTMLOutputElement, in §4.10.13
- defaultView, in §6.3
-
defer
- element-attr for script, in §4.12.1
- attribute for HTMLScriptElement, in §4.12.1
- defines a command, in §4.11.6.1
- defines the term, in §4.5.8
- defining term, in §4.5.8
- del, in §4.6.2
- delaying load events mode, in §6.1.1
- delaying the load event, in §8.2.6
- delaying-the-load-event flag, in §4.7.14.5
- delays the load event, in §8.2.6
- delay the load event, in §8.2.6
- delete an existing named property, in §2.7.3
- deleteCaption(), in §4.9.1
- deleteCell(index), in §4.9.8
-
deleteRow(index)
- method for HTMLTableElement, in §4.9.1
- method for HTMLTableSectionElement, in §4.9.5
- deleteTFoot(), in §4.9.1
- deleteTHead(), in §4.9.1
- delete the selection, in §5.6.4
- density-corrected intrinsic width and height, in §4.7.5
- dereferencing a javascript: url, in §6.7.1
- derived from country in some cases, in §4.10.19.8.2
- described above, in §4.7.5.1.16
-
description
- definition of, in §4.2.5.1
- attribute for Plugin, in §7.6.1.5
- attribute for MimeType, in §7.6.1.5
-
descriptions
- attr-value for track/kind, in §4.7.13
- attr-value for commonTrack/kind, in §4.7.14.10.1
- definition of, in §4.7.14.11.1
- enum-value for TextTrackKind, in §4.7.14.11.5
- "descriptions", in §4.7.14.11.5
- Descriptions, in §4.7.13
- designated pop-up menu, in §4.10.6
-
designMode
- attribute for Document, in §3.1.1
- definition of, in §5.6.2
- Detached, in §2.9.2
- detach from a media element, in §2.2.2
- details, in §4.11.1
- details notification task steps, in §4.11.1
- determining the type of the resource, in §4.2.4
- device-pixel-ratio, in §4.7.1
- dfn, in §4.5.8
- dialog arguments, in §7.5.3
- dialogArguments, in §7.5.3
- dialog arguments' origin, in §7.5.3
- did-perform-automatic-track-selection, in §4.7.14.11.1
- Dimension attributes, in §4.7.20
-
dir
- attribute for Document, in §3.1.1
- element-attr for global, in §3.2.5.6
- (element), in §11.2
-
direction
- element-attr for marquee, in §11.3.2
- attribute for HTMLMarqueeElement, in §11.3.2
- directionality, in §3.2.5.6
- directionality-capable attributes, in §3.2.5.6
- directionality of an attribute, in §3.2.5.6
- directionality of the attribute, in §3.2.5.6
- direction of playback, in §4.7.14.8
- directly reachable browsing contexts, in §6.1.4
- :dir(ltr), in §4.15.2
- dirname, in §4.10.19.2
-
dirName
- attribute for HTMLInputElement, in §4.10.5
- attribute for HTMLTextAreaElement, in §4.10.11
- :dir(rtl), in §4.15.2
- dirtiness, in §4.10.10
- dirty checkedness, in §4.10.5
- dirty checkedness flag, in §4.10.5
-
dirty value flag
- dfn for input, in §4.10.5
- dfn for textarea, in §4.10.11
- :disabled, in §4.15.2
- "disabled", in §4.7.14.11.5
-
disabled
- mode for track, in §4.7.14.11.1
- enum-value for TextTrackMode, in §4.7.14.11.5
- enum for TextTrackMode, in §4.7.14.11.5
- element-attr for optgroup, in §4.10.9
- attribute for HTMLOptGroupElement, in §4.10.9
- element-attr for option, in §4.10.10
- attribute for HTMLOptionElement, in §4.10.10
- element-attr for fieldset, in §4.10.16
- attribute for HTMLFieldSetElement, in §4.10.16
- element-attr for disabledformelements, input, button, keygen, select, textarea, in §4.10.19.5
- attribute for HTMLInputElement, HTMLButtonElement, HTMLSelectElement, HTMLTextAreaElement, HTMLKeygenElement, in §4.10.19.5
- element-attr for menuitem, in §4.11.4
- attribute for HTMLMenuItemElement, in §4.11.4
- disabled fieldset, in §4.10.16
- Disabled State, in §4.11.6.1
- disabling, in §4.14
- discard, in §6.3.4
- discard a document, in §6.3.4
- discarded, in §6.3.4
- discard the document, in §6.3.4
- disown its opener, in §6.1.2.1
- dispatch, in §2.1.4
- dispatched, in §2.1.4
- dispatching, in §2.1.4
- displayed, in §2.1
- display size, in §4.10.7
- display state, in §4.7.14.11.1
- display the inline content, in §6.7.8
- div, in §4.4.14
- dl, in §4.4.8
- DOCTYPE, in §8.1.1
- DOCTYPE legacy string, in §8.1.1
-
document
- definition of, in §2.1
- attribute for Window, in §6.3
- Document, in §3.1.1
- DocumentAndElementEventHandlers, in §7.1.5.2.1
- document associated with a window, in §6.1
- document base URL, in §2.5.1
- document family, in §6.1.1
- documents, in §2.1
- does not apply, in §4.10.5
- doesn’t apply, in §4.10.5
- doesn’t necessarily have to affect, in §6.6.3
- domain, in §6.4.1
- DOM anchor, in §5.4.2
- DOMContentLoaded, in §Unnumbered section
- DOMElementMap, in §2.7.4
- dom event dispatch logic, in §2.1.4
- DOM interface, in §3.2.3
- DOM manipulation task source, in §7.1.4.3
- DOMStringMap, in §2.7.3
- do not apply, in §4.10.5
- do not set, in §3.2.7.1
- do not support scripting, in §2.2.1
- don’t apply, in §4.10.5
-
down
- attr-value for marquee/direction, in §10.5.11
- state for marquee, in §11.3.2
-
download
- attribute for HTMLAnchorElement, in §4.5.1
- attribute for HTMLAreaElement, in §4.7.16
- element-attr for a, area, links, in §4.8.2
- definition of, in §4.8.5
- download hyperlinks, in §4.8.5
- DOWNLOADING, in §11.3.4.8
- downloads a hyperlink, in §4.8.5
- download the hyperlink, in §4.8.5
- drag, in §5.7.6
- drag-and-drop events, in §5.7.6
- drag data item kind, in §5.7.2
- drag data item type string, in §5.7.2
- drag data item type strings, in §5.7.2
- drag data store, in §5.7.2
- drag data store allowed effects state, in §5.7.2
- drag data store bitmap, in §5.7.2
- drag data store default feedback, in §5.7.2
- drag data store hot spot coordinate, in §5.7.2
- drag data store item list, in §5.7.2
- drag data store mode, in §5.7.2
- dragend, in §5.7.6
- dragenter, in §5.7.6
- DragEvent, in §5.7.4
- DragEvent(type), in §5.7.4
- DragEvent(type, eventInitDict), in §5.7.4
- dragexit, in §5.7.6
-
draggable
- element-attr for global, in §5.7.7
- attribute for HTMLElement, in §5.7.7
- dragleave, in §5.7.6
- dragover, in §5.7.6
- dragstart, in §5.7.6
- drop, in §5.7.6
- dropEffect, in §5.7.3
-
dropzone
- element-attr for global, in §5.7.8
- attribute for HTMLElement, in §5.7.8
- dropzone processing steps, in §5.7.8
- dt, in §4.4.9
-
duration
- definition of, in §2.4.5.9
- attribute for HTMLMediaElement, in §4.7.14.6
- durationchange, in §4.7.14.15
- duration time component, in §2.4.5.9
- duration time component scale, in §2.4.5.9
- during form submission, in §4.10.22.4
- dynamic markup insertion, in §7.3
- earliest possible position, in §4.7.14.6
- earliest possible position when the script started, in §4.7.14.11.5
- editable, in §5.6.4
- editing host, in §5.6.4
- effectAllowed, in §5.7.3
- effective domain, in §6.4
- effective media volume, in §4.7.14.12
- effective playback rate, in §4.7.14.8
- ElementContentEditable, in §5.6.1
- element has the focus, in §4.15.2
-
elements
- attribute for HTMLFormElement, in §4.10.3
- attribute for HTMLFieldSetElement, in §4.10.16
- elements with default margins, in §10.3.10
- element type, in §2.1.2
- element with default margins, in §10.3.10
- em, in §4.5.2
- E-mail, in §4.10.19.7
-
email
- attr-value for input/type, in §4.10.5
- element-state for input, in §4.10.5.1.5
- value for form/inputmode, in §4.10.19.7
- e-mail, in §4.10.5.1.5
- embed, in §4.7.7
- embedded content, in §3.2.4.2.6
- Embedding custom non-visible data, in §3.2.5.9
- embeds, in §3.1.3
- embed task source, in §4.7.7
- emptied, in §4.7.14.15
- empty, in §2.1.3
- empty cell, in §4.9.12.2
- enabled, in §4.7.14.10.1
- :enabled, in §4.15.2
- enabledPlugin, in §7.6.1.5
- encoding, in §4.10.19.6
- encoding declaration state, in §4.2.5.3
- encoding labels, in §2.1.6
- encoding name, in §2.1.6
- encoding sniffing algorithm, in §8.2.2.2
-
enctype
- element-attr for form, in §4.10.19.6
- definition of, in §4.10.19.6
- attribute for HTMLFormElement, in §4.10.19.6
-
end
- enum-value for SelectionMode, in §4.10.20
- enum for SelectionMode, in §4.10.20
- "end", in §4.10.20
-
ended
- definition of, in §4.7.14.8
- event for media, in §4.7.14.15
- ended playback, in §4.7.14.8
- end(index), in §4.7.14.13
- end tag, in §8.1.2.2
- end tags, in §8.1.2.2
- endTime, in §4.7.14.11.5
- enter, in §4.7.14.15
- entrance counter, in §7.1.3.5.1
- Entry, in §7.1.3.5
- entry execution context, in §7.1.3.5.1
- entry global object, in §7.1.3.5.1
- entry Realm, in §7.1.3.5.1
- entry settings object, in §7.1.3.5.1
- entry update, in §6.7.1
- enumerated attributes, in §2.4.3
- environment settings object, in §7.1.3.1
-
error
- attribute for HTMLMediaElement, in §4.7.14.1
- event for media, in §4.7.14.15
- event for source, in §4.7.14.15
- event for track, in §4.7.14.15
- attribute for ErrorEvent, in §7.1.3.8.2
- event for global, in §Unnumbered section
- ERROR, in §4.7.13
- ErrorEvent, in §7.1.3.8.2
- ErrorEvent(type), in §7.1.3.8.2
- ErrorEvent(type, eventInitDict), in §7.1.3.8.2
- error occurs during reading of the object, in §2.2.2
- escapable raw text, in §8.1.2
- escapable raw text elements, in §8.1.2
- Escaping a string, in §8.3
- establish a WebSocket connection, in §2.2.2
- establishing the media timeline, in §4.7.14.6
- establish the media timeline, in §4.7.14.6
- EUC-KR, in §8.2.2.3
-
event
- element-attr for script, in §11.2
- attribute for HTMLScriptElement, in §11.3.5
- event dispatching, in §2.1.4
- event handler, in §7.1.5.1
- event handler content attribute, in §7.1.5.1
- event handler content attributes, in §7.1.5.1
- event handler event type, in §7.1.5.1
- event handler IDL attribute, in §7.1.5.1
- event handler IDL attributes, in §7.1.5.1
- event handlers, in §7.1.5.1
- event loop, in §7.1.4.1
- event loops, in §7.1.4.1
- event parent, in §2.2.2
- exceptions enabled flag, in §6.7.1
- execCommand(), in §5.6.4
- execCommand(commandId), in §3.1.1
- execCommand(commandId, showUI), in §3.1.1
- execCommand(commandId, showUI, value), in §3.1.1
- execute, in §4.12.1.1
- execute a compound microtask subtask, in §7.1.4.2
- execute a script block, in §4.12.1.1
- execute the script block, in §4.12.1.1
- existing, in §2.7.4
- exit, in §4.7.14.15
- explicit content-type metadata, in §2.6.4
- explicit entries, in §11.3.4
- explicit "EOF" character, in §8.2.2.5
- explicitly going back or forwards in the session history, in §6.6.2
- explicitly supported, in §7.6.1.5
- explicitly supported JSON type, in §6.7.1
- explicitly supported XML type, in §6.7.1
- explicitly supports, in §7.6.1.5
- explicit section, in §11.3.4.1
- expose a user interface to the user, in §4.7.14.12
- exposed, in §3.1.3
- exposes a user interface to the user, in §4.7.14.12
- exposing a user interface, in §4.7.14.12
- exposing a user interface to the user, in §4.7.14.12
- expressly inert, in §5.4.2
- extension, in §4.8.5
- extensions in use, in §2.2.2
- extensions to the predefined set of link type, in §4.8.6.13
- extensions to the predefined set of link types, in §4.8.6.13
- Extensions to the predefined set of pragma directives, in §4.2.5.4
- External, in §11.3.5
- external, in §11.3.5
- external resource, in §4.8.1
- external resource link, in §4.8.1
- external resources, in §4.8.1
- face, in §11.3.5
- facets, in §4.11.6.1
- failed, in §4.7.14.11.1
- failed to load, in §4.7.14.11.1
- fail the WebSocket connection, in §2.2.2
- fallback base URL, in §2.5.1
- fallback content, in §3.2.4.2.6
- fallback entries, in §11.3.4
- fallback namespaces, in §11.3.4
- fallback section, in §11.3.4.1
- false-by-default, in §5.6.5
- familiar with, in §6.1.3
- fast, in §11.3.4
- fastSeek(time), in §4.7.14.9
- feed the parser, in §9.2
- fetch a classic script, in §7.1.3.2
- fetch a classic worker script, in §7.1.3.2
- fetching a classic script, in §7.1.3.2
- Fetching scripts, in §7.1.3.2
- fgColor, in §11.3.5
- fieldset, in §4.10.16
- figcaption, in §4.4.12
- figure, in §4.4.11
- file, in §4.10.5
-
filename
- mode for input, in §4.10.5.4
- attribute for ErrorEvent, in §7.1.3.8.2
- attribute for Plugin, in §7.6.1.5
-
files
- attribute for HTMLInputElement, in §4.10.5.4
- attribute for DataTransfer, in §5.7.3
- file upload, in §4.10.5.1.17
- file upload controls, in §4.10.5.1.17
- finish, in §11.3.2
- finishes, in §8.2.6
- fire, in §2.1.4
- fire a click event, in §7.1.5.3
- fire a DND event, in §5.7.4
- fire a focus event, in §5.4.4
- fire a progress event, in §4.7.5
- fire a progress event or simple event, in §4.7.5
- fire a simple event, in §2.1.4
- fire a synthetic mouse event named contextmenu, in §7.1.5.3
- fired, in §2.1.4
- fired unload, in §6.7.11
- fires, in §2.1.4
- fires a simple event, in §2.1.4
- firing, in §2.1.4
- firing a click event, in §7.1.5.3
- firing a simple event, in §7.1.5.3
- firing a simple event named e, in §7.1.5.3
- firing a synthetic mouse event named click, in §7.1.5.3
- Firing a synthetic mouse event named e, in §7.1.5.3
- floating date and time, in §2.4.5.5
- flow content, in §3.2.4.2.2
- focus(), in §5.4.6
- focus, in §Unnumbered section
- :focus, in §4.15.2
- focusable, in §5.4.2
- focusable area, in §5.4.2
- focus chain, in §5.4.2
- focused, in §5.4.2
- focused area, in §5.4.2
- focused area of a control group, in §5.4.2
- focused area of that focus group, in §5.4.2
- focused area of the control group, in §5.4.2
- focused dialog, in §5.4.2
- Focus fixup rule one, in §5.4.4
- focusing steps, in §5.4.4
- focus update steps, in §5.4.4
- follow hyperlinks, in §4.8.4
- following a hyperlink, in §4.8.4
- following hyperlinks, in §4.8.4
- follows a hyperlink, in §4.8.4
- follow the hyperlink, in §4.8.4
- follow the hyperlinks, in §4.8.4
- font, in §11.2
- footer, in §4.3.8
-
for
- element-attr for label, in §4.10.4
- element-attr for output, in §4.10.13
- element-attr for script, in §11.2
- forced sandboxing flag set, in §6.5
- force-quirks flag, in §8.2.4
- forces content into a unique origin, in §6.4
- forceSpellCheck(), in §5.6.5
- foreign, in §11.3.4
- Foreign elements, in §8.1.2
- forget the media element’s media-resource-specific tracks, in §4.7.14.5
-
form
- (element), in §4.10.3
- element-attr for formelements, object, label, input, button, select, textarea, keygen, output, fieldset, in §4.10.18.3
- attribute for FormIDLAttribute, HTMLObjectElement, HTMLLabelElement, HTMLInputElement, HTMLButtonElement, HTMLSelectElement, HTMLOptionElement, HTMLTextAreaElement, HTMLKeygenElement, HTMLOutputElement, HTMLFieldSetElement, HTMLLegendElement, in §4.10.18.3
- formaction, in §4.10.19.6
- formAction, in §4.10.19.6
- form-associated, in §4.10.2
- form-associated elements, in §4.10.2
- formatting, in §8.2.3.2
- formatting element tags, in §8.2.3.2
- form control maxlength attribute, in §4.10.19.3
- form control minlength attribute, in §4.10.19.4
- form element pointer, in §8.2.3.4
- formEnctype, in §4.10.19.6
- formenctype, in §4.10.19.6
- formMethod, in §4.10.19.6
- formmethod, in §4.10.19.6
- formNoValidate, in §4.10.19.6
- formnovalidate, in §4.10.19.6
- form owner, in §4.10.18.3
- Forms, in §4.10
- forms, in §3.1.3
- form submission, in §4.10.22
- form submission algorithm, in §4.10.22.3
- form submissions, in §4.10.22
- formTarget, in §4.10.19.6
- formtarget, in §4.10.19.6
- for privacy, in §1.8
- forward(), in §6.6.2
- foster parent, in §8.2.5.1
- foster parented, in §8.2.5.1
- foster parenting, in §8.2.5.1
- fragment case, in §8.4
- fragment identifier, in §6.7.9
- fragment identifiers, in §6.7.9
-
frame
- element-attr for table, in §11.2
- (element), in §11.3.3
- attribute for HTMLTableElement, in §11.3.5
- frameborder, in §11.2
-
frameBorder
- attribute for HTMLFrameElement, in §11.3.3
- attribute for HTMLIFrameElement, in §11.3.5
- frame border color, in §10.6
- frameElement, in §6.1.1.1
- frames, in §6.3
- frameset, in §11.3.3
- frameset-ok flag, in §8.2.3.5
- framespacing, in §11.2
- from an external file, in §4.12.1.1
- frozen base URL, in §4.2.3
- Full-width Latin, in §4.10.19.7
- full-width-latin, in §4.10.19.7
- fully active, in §6.1.1
- fully decodable, in §4.7.5
- further restrictions, in §8.1.2.6
- gain focus, in §5.4.2
- gb18030, in §8.2.2.3
- generate all implied end tags thoroughly, in §8.2.5.3
- generate implied end tags, in §8.2.5.3
- generator, in §4.2.5.1
- generator-unable-to-provide-required-alt, in §4.7.5.1.22
- generic raw text element parsing algorithm, in §8.2.5.2
- generic RCDATA element parsing algorithm, in §8.2.5.2
- get, in §4.10.19.6
- GET, in §4.10.19.6
- Get action URL, in §4.10.22.3
- get all-indexed, in §2.7.2.1
- get all-named, in §2.7.2.1
- get an attribute, in §8.2.2.2
- getAsFile(), in §5.7.3.2
- getAsString(_callback), in §5.7.3.2
- getContext(contextId, arguments...), in §4.12.4
- getContext(contextId, arguments), in §4.12.4
- getCueById(id), in §4.7.14.11.5
- getData(format), in §5.7.3
- getElementsByName(), in §3.1.3
- getElementsByName(elementName), in §3.1.1
- gets reset, in §6.7.10
- getStartDate(), in §4.7.14.6
- get the current value of the event handler, in §7.1.5.1
- getting, in §2.1.4
- Getting an encoding, in §2.2.2
- getting an output encoding, in §2.2.2
- getting the current value of the event handler, in §7.1.5.1
-
getTrackById(id)
- method for AudioTrackList, in §4.7.14.10.1
- method for VideoTrackList, in §4.7.14.10.1
- method for TextTrackList, in §4.7.14.11.5
- global aria-* attributes, in §3.2.7.3.2
- Global attributes, in §3.2.5
- global date and time, in §2.4.5.7
- GlobalEventHandlers, in §7.1.5.2.1
- global object, in §7.1.3.5
- global script clean-up jobs list, in §7.1.3.4
- global States and properties, in §3.2.7.3.2
- go(), in §6.6.2
- go(delta), in §6.6.2
- group, in §4.9.12
- Guidelines for exposing cues, in §4.7.14.11.4
- h1, in §4.3.6
- h2, in §4.3.6
- h3, in §4.3.6
- h4, in §4.3.6
- h5, in §4.3.6
- h6, in §4.3.6
-
handled
- dfn for script, in §7.1.3.8
- dfn for promise, in §7.1.3.9
- hard, in §4.10.11
- Hard, in §4.10.11
- hardware limitations, in §2.2.1
- has a border, in §10.6
- has an effect, in §11.3.4.3
- has a p element in button scope, in §8.2.3.2
- has a periodic domain, in §4.10.5.3.7
- has a reversed range, in §4.10.5.3.7
- has a style sheet that is blocking scripts, in §4.2.7
- hasFocus(), in §5.4.6
- has focus steps, in §5.4.4
-
hash
- attribute for HTMLHyperlinkElementUtils, in §4.8.3
- attribute for Location, in §6.6.4
- hashchange, in §Unnumbered section
- HashChangeEvent, in §6.7.10.3
- HashChangeEvent(type), in §6.7.10.3
- HashChangeEvent(type, eventInitDict), in §6.7.10.3
- @@hasInstance, in §2.2.2
- has no style sheet that is blocking scripts, in §4.2.7
- has range limitations, in §4.10.5.3.7
- has that element in the specific scope, in §8.2.3.2
- have an element in table scope, in §8.2.3.2
- have an element target node in a specific scope, in §8.2.3.2
- have an li element in list item scope, in §8.2.3.2
- have a particular element in button scope, in §8.2.3.2
- have a particular element in list item scope, in §8.2.3.2
- have a particular element in select scope, in §8.2.3.2
- have a particular element in table scope, in §8.2.3.2
- have a p element in button scope, in §8.2.3.2
- have a periodic domain, in §4.10.5.3.7
- have a reversed range, in §4.10.5.3.7
- have a style sheet that is blocking scripts, in §4.2.7
- HAVE_CURRENT_DATA, in §4.7.14.7
- HAVE_ENOUGH_DATA, in §4.7.14.7
- HAVE_FUTURE_DATA, in §4.7.14.7
- HAVE_METADATA, in §4.7.14.7
- HAVE_NOTHING, in §4.7.14.7
- have range limitations, in §4.10.5.3.7
-
head
- attribute for Document, in §3.1.3
- (element), in §4.2.1
- head element pointer, in §8.2.3.4
- header, in §4.3.7
-
headers
- element-attr for tablecells, in §4.9.11
- attribute for HTMLTableCellElement, in §4.9.11
- headers to send appropriate cookies, in §2.2.2
- heading content, in §3.2.4.2.4
- headings, in §3.2.4.2.4
-
height
- attribute for HTMLImageElement, in §4.7.5
- attribute for HTMLIFrameElement, in §4.7.6
- attribute for HTMLEmbedElement, in §4.7.7
- attribute for HTMLObjectElement, in §4.7.8
- element-attr for media, img, iframe, embed, object, video, input, in §4.7.20
- attribute for media, in §4.7.20
- attribute for HTMLInputElement, in §4.10.5
- element-attr for canvas, in §4.12.4
- attribute for HTMLCanvasElement, in §4.12.4
- attribute for ImageBitmap, in §7.7
- element-attr for table, in §11.2
- element-attr for td, th, tablecells, in §11.2
- element-attr for tr, in §11.2
- attribute for HTMLAppletElement, in §11.3.1
- attribute for HTMLMarqueeElement, in §11.3.2
- attribute for HTMLTableCellElement, in §11.3.5
- help, in §4.8.6.4
-
hidden
- mode for track, in §4.7.14.11.1
- enum-value for TextTrackMode, in §4.7.14.11.5
- enum for TextTrackMode, in §4.7.14.11.5
- attr-value for input/type, in §4.10.5
- definition of, in §5.1
- attribute for common, in §5.1
- Hidden, in §4.10.5.1.1
- "hidden", in §4.7.14.11.5
- hidden plugins, in §7.6.1.5
- Hidden State, in §4.11.6.1
-
high
- element-attr for meter, in §4.10.15
- attribute for HTMLMeterElement, in §4.10.15
- high boundary, in §4.10.15
- History, in §6.6.2
- history, in §6.6.1
- history traversal, in §6.7.10
- history traversal task source, in §7.1.4.3
- home control group, in §5.4.5
- home sequential focus navigation order, in §5.4.5
- home subtree, in §2.1.3
- home subtrees, in §2.1.3
- honor user preferences for automatic text track selection, in §4.7.14.11.3
-
host
- attribute for HTMLHyperlinkElementUtils, in §4.8.3
- attribute for Location, in §6.6.4
-
hostname
- attribute for HTMLHyperlinkElementUtils, in §4.8.3
- attribute for Location, in §6.6.4
- :hover, in §4.15.2
- hr, in §4.4.2
-
href
- element-attr for base, in §4.2.3
- attribute for HTMLBaseElement, in §4.2.3
- element-attr for link, in §4.2.4
- attribute for HTMLLinkElement, in §4.2.4
- element-attr for a, area, links, in §4.8.2
- attribute for HTMLHyperlinkElementUtils, in §4.8.3
- attribute for Location, in §6.6.4
-
hreflang
- element-attr for link, in §4.2.4
- attribute for HTMLLinkElement, in §4.2.4
- attribute for HTMLAnchorElement, in §4.5.1
- attribute for HTMLAreaElement, in §4.7.16
- element-attr for a, links, in §4.8.2
-
hspace
- element-attr for embed, in §11.2
- element-attr for iframe, in §11.2
- element-attr for input, in §11.2
- element-attr for img, in §11.2
- element-attr for object, in §11.2
- attribute for HTMLAppletElement, in §11.3.1
- attribute for HTMLMarqueeElement, in §11.3.2
- attribute for HTMLImageElement, in §11.3.5
- attribute for HTMLObjectElement, in §11.3.5
- html, in §4.1.1
- HTMLAllCollection, in §2.7.2.1
- HTMLAnchorElement, in §4.5.1
- HTMLAppletElement, in §11.3.1
- HTMLAreaElement, in §4.7.16
- HTMLAudioElement, in §4.7.11
- HTMLBaseElement, in §4.2.3
- HTMLBodyElement, in §4.3.1
- HTMLBRElement, in §4.5.29
- HTMLButtonElement, in §4.10.6
- HTMLCanvasElement, in §4.12.4
- html-contents, in §3.2.4
- HTMLDataElement, in §4.5.15
- HTMLDataListElement, in §4.10.8
- HTMLDetailsElement, in §4.11.1
- HTMLDirectoryElement, in §11.3.5
- HTMLDivElement, in §4.4.14
- HTMLDListElement, in §4.4.8
- HTMLDocument, in §6.3
- HTML document, in §2.1
- html element, in §2.1.2
- HTMLElement, in §3.2.2
- html elements, in §2.1.2
- HTMLEmbedElement, in §4.7.7
- HTMLFieldSetElement, in §4.10.16
- HTMLFontElement, in §11.3.5
-
htmlFor
- attribute for HTMLLabelElement, in §4.10.4
- attribute for HTMLOutputElement, in §4.10.13
- attribute for HTMLScriptElement, in §11.3.5
- HTMLFormControlsCollection, in §2.7.2.2
- HTMLFormElement, in §4.10.3
- HTML fragment parsing algorithm, in §8.4
- HTML fragment serialization algorithm, in §8.3
- HTMLFrameElement, in §11.3.3
- HTMLFrameSetElement, in §11.3.3
- HTMLHeadElement, in §4.2.1
- HTMLHeadingElement, in §4.3.6
- HTMLHRElement, in §4.4.2
- HTMLHtmlElement, in §4.1.1
- HTMLHyperlinkElementUtils, in §4.8.3
- HTMLIFrameElement, in §4.7.6
- HTMLImageElement, in §4.7.5
- HTMLInputElement, in §4.10.5
- HTML integration point, in §8.2.5
- HTMLKeygenElement, in §4.10.12
- HTMLLabelElement, in §4.10.4
- HTMLLegendElement, in §4.10.17
- HTMLLIElement, in §4.4.7
- HTMLLinkElement, in §4.2.4
- html link types, in §4.8.6
- HTMLMapElement, in §4.7.15
- HTMLMarqueeElement, in §11.3.2
- HTMLMediaElement, in §4.7.14
- HTMLMenuElement, in §4.11.3
- HTMLMenuItemElement, in §4.11.4
- HTMLMetaElement, in §4.2.5
- HTMLMeterElement, in §4.10.15
- HTML MIME type, in §2.1.1
- HTMLModElement, in §4.6.3
- HTML namespace, in §2.8
- HTMLObjectElement, in §4.7.8
- HTMLOListElement, in §4.4.5
- HTMLOptGroupElement, in §4.10.9
- HTMLOptionElement, in §4.10.10
- HTMLOptionsCollection, in §2.7.2.3
- HTMLOutputElement, in §4.10.13
- HTMLParagraphElement, in §4.4.1
- HTMLParamElement, in §4.7.9
- HTML parser, in §8.2
- HTMLPictureElement, in §4.7.3
- HTMLPreElement, in §4.4.3
- HTMLProgressElement, in §4.10.14
- HTMLQuoteElement, in §4.4.4
- HTMLScriptElement, in §4.12.1
- HTMLSelectElement, in §4.10.7
- HTMLSourceElement, in §4.7.12
- HTMLSpanElement, in §4.5.28
- HTMLStyleElement, in §4.2.6
- HTMLTableCaptionElement, in §4.9.2
- HTMLTableCellElement, in §4.9.11
- HTMLTableColElement, in §4.9.3
- HTMLTableDataCellElement, in §4.9.9
- HTMLTableElement, in §4.9.1
- HTMLTableHeaderCellElement, in §4.9.10
- HTMLTableRowElement, in §4.9.8
- HTMLTableSectionElement, in §4.9.5
- HTMLTemplateElement, in §4.12.3
- HTMLTextAreaElement, in §4.10.11
- HTMLTimeElement, in §4.5.16
- HTMLTitleElement, in §4.2.2
- HTMLTrackElement, in §4.7.13
- HTMLUListElement, in §4.4.6
- HTMLUnknownElement, in §3.2.2
- HTMLVideoElement, in §4.7.10
- http:, in §2.2.2
-
http-equiv
- element-attr for meta, in §4.2.5
- definition of, in §4.2.5.3
- httpEquiv, in §4.2.5
- HTTP GET method, in §2.6.1
- HTTP headers, in §2.6.1
- HTTP response codes, in §2.6.1
- https:, in §2.2.2
-
HTTPS state
- dfn for document, in §3.1.1
- dfn for settings, in §7.1.3.1
- hyperlink, in §4.8.1
- hyperlink annotations, in §4.8.1
- hyperlinks, in §4.8.1
-
i
- attr-value for ol/type, in §4.4.5
- (element), in §4.5.22
-
icon
- value for link/type, in §4.8.6.5
- element-attr for menuitem, in §4.11.4
- attribute for HTMLMenuItemElement, in §4.11.4
-
id
- element-attr for global, in §3.2.5.1
- attribute for AudioTrack, in §4.7.14.10.1
- attribute for VideoTrack, in §4.7.14.10.1
- attribute for TextTrack, in §4.7.14.11.5
- attribute for TextTrackCue, in §4.7.14.11.5
- IDL attribute, in §2.1
- IDL attributes, in §2.1
- IDLE, in §11.3.4.8
- IDL-exposed autofill value, in §4.10.19.8.2
- if appropriate, in §5.7.4
- iframe, in §4.7.6
- iframe load event steps, in §4.7.6
- iframe load in progress, in §4.7.6
- iframe sandboxing flag set, in §6.5
- iframe srcdoc document, in §4.7.6
- ignored, in §2.1.3
- ignore-destructive-writes counter, in §7.3.3
- ignored ruby content, in §4.5.10
- ignore higher-layer caching, in §4.7.5
- ignore-opens-during-unload counter, in §7.3.1
- image, in §4.10.5
- ImageBitmap, in §7.7
- ImageBitmapFactories, in §7.7
- Image Button, in §4.10.5.1.19
- image candidate string, in §4.7.5
- image data, in §4.7.5
- image format-based selection, in §4.7.1
- image map, in §4.7.17
- image maps, in §4.7.17
- image request, in §4.7.5
-
images
- attribute for Document, in §3.1.3
- attribute for HTMLMapElement, in §4.7.15
- image sniffing, in §2.6.4
- image sniffing rules, in §2.6.4
- image source, in §4.7.5
- Image(width, height), in §4.7.5
- img, in §4.7.5
- immediately, in §2.1
- immediate user selection, in §5.7.5
- implementation notes, in §4.10.5.2
- Implementation notes for session history, in §6.6.3
- implement the sandboxing, in §6.5
- implied, in §3.2.4.4
- implied paragraph, in §3.2.4.4
- implied paragraphs, in §3.2.4.4
- implied strong reference, in §2.7.5
- in a document, in §2.1.3
- in a formal activation state, in §4.15.2
- inappropriate for a control, in §4.10.19.8.1
- inappropriate for the control, in §4.10.19.8.1
- in-band metadata track dispatch type, in §4.7.14.11.1
- inBandMetadataTrackDispatchType, in §4.7.14.11.5
- in body, in §8.2.5.4.7
- in caption, in §8.2.5.4.11
- in cell, in §8.2.5.4.15
- in column group, in §8.2.5.4.12
- increment the marquee current loop index, in §11.3.2
- Incumbent, in §7.1.3.5
- incumbent global object, in §7.1.3.5.2
- incumbent Realm, in §7.1.3.5.2
- incumbent settings object, in §7.1.3.5.2
- indeterminate, in §4.10.5
- :indeterminate, in §4.15.2
-
index
- dfn for option, in §4.10.10
- attribute for HTMLOptionElement, in §4.10.10
- indexed for indexed property retrieval, in §4.10.3
- indexed for named property retrieval, in §4.10.3
- indicated a coordinate, in §4.10.5.1.19
- indicated part of the document, in §6.7.9
- in error reporting mode, in §7.1.3.8
- inert, in §5.2
- inertness, in §5.2
- in foreign content, in §8.2.5.5
- in frameset, in §8.2.5.4.20
- in head, in §8.2.5.4.4
- in head noscript, in §8.2.5.4.5
- inherit-by-default, in §5.6.5
- initial, in §8.2.5.4.1
- Initializing a new Document object, in §6.7.1
- initial playback position, in §4.7.14.6
- initiated, in §5.7.5
- initiate the drag-and-drop operation, in §5.7.5
- in parallel, in §2.1
-
input
- (element), in §4.10.5
- event for input, in §4.10.5.5
- event for global, in §Unnumbered section
- input byte stream, in §8.2.2
-
inputMode
- attribute for HTMLInputElement, in §4.10.5
- attribute for HTMLTextAreaElement, in §4.10.11
-
inputmode
- element-attr for textarea, in §4.10.11
- element-attr for input, in §4.10.19.7
- input stream, in §8.2.2.5
- :in-range, in §4.15.2
- in row, in §8.2.5.4.14
- ins, in §4.6.1
- in scope, in §8.2.3.2
- in select, in §8.2.5.4.16
- in select in table, in §8.2.5.4.17
- insert a character, in §8.2.5.1
- insert a comment, in §8.2.5.1
- insert a foreign element, in §8.2.5.1
- insert an HTML element, in §8.2.5.1
- insertCell(index), in §4.9.8
- insert characters, in §8.2.5.1
- inserted into, in §2.1.3
- inserted into a document, in §2.1.3
- inserted into the document, in §2.1.3
- insertion mode, in §8.2.3.1
- insertion point, in §8.2.2.5
-
insertRow(index)
- method for HTMLTableElement, in §4.9.1
- method for HTMLTableSectionElement, in §4.9.5
- insert the character, in §8.2.5.1
- insert the token’s character, in §8.2.5.1
- in table, in §8.2.5.4.9
- in table body, in §8.2.5.4.13
- in table scope, in §8.2.3.2
- in table text, in §8.2.5.4.10
- in template, in §8.2.5.4.18
- interactive, in §3.1.1
- "interactive", in §3.1.1
- interactive content, in §3.2.4.2.7
- interactively validate the constraints, in §4.10.21.2
- inter-element whitespace, in §3.2.4
- internal algorithm for scanning and assigning header cells, in §4.9.12.2
- internal pause steps, in §4.7.14.8
- internal raw uncompiled handler, in §7.1.5.1
- in the document, in §2.1.3
- in the html parser, in §8.2.5.4.2
- in the parser, in §8.2.5.4.2
- intrinsic dimensions, in §2.2.2
-
intrinsic height
- dfn for css, in §2.2.2
- dfn for video, in §4.7.10
-
intrinsic width
- dfn for css, in §2.2.2
- dfn for video, in §4.7.10
- invalid, in §Unnumbered section
- :invalid, in §4.15.2
- invalid value default, in §2.4.3
- invoke, in §7.1.5.1
- @@isConcatSpreadable, in §2.2.2
- isContentEditable, in §5.6.1
- isindex, in §11.2
- isMap, in §4.7.5
-
ismap
- element-attr for img, in §4.7.5
- element-attr for input, in §11.2
- is not step aligned, in §4.10.5.4
- ISO-2022-JP, in §8.2.2.3
- ISO-8859-2, in §8.2.2.3
- ISO-8859-8, in §8.2.2.3
- IsPlatformObjectSameOrigin, in §6.2.3.2
- IsSearchProviderInstalled(), in §11.3.5
- is step aligned, in §4.10.5.4
- IsTransferable, in §2.9.5
- it can also come from script, in §7.3
- item(), in §2.7.2.1
-
item(index)
- method for HTMLSelectElement, in §4.10.7
- method for PluginArray, in §7.6.1.5
- method for MimeTypeArray, in §7.6.1.5
- method for Plugin, in §7.6.1.5
- item(nameOrItem), in §2.7.2.1
- items, in §5.7.3
- item type string, in §5.7.2
- javaEnabled(), in §7.6.1.5
- JavaScript MIME type, in §4.12.1.2
- javascript: url, in §6.7.1
- javascript: urls, in §6.7.1
- joint session history, in §6.6.2
- JSON MIME type, in §6.7.1
- kana, in §4.10.19.7
- Kana, in §4.10.19.7
- kana-name, in §4.10.19.7
- Kana Name, in §4.10.19.7
- Katakana, in §4.10.19.7
- katakana, in §4.10.19.7
- kbd, in §4.5.20
- keygen, in §4.10.12
-
keytype
- element-attr for keygen, in §4.10.12
- attribute for HTMLKeygenElement, in §4.10.12
- keywords, in §4.2.5.1
-
kind
- element-attr for track, in §4.7.13
- attribute for HTMLTrackElement, in §4.7.13
- attribute for AudioTrack, in §4.7.14.10.1
- attribute for VideoTrack, in §4.7.14.10.1
- definition of, in §4.7.14.11.1
- attribute for TextTrack, in §4.7.14.11.5
- attribute for DataTransferItem, in §5.7.3.2
- kind of element, in §8.1.2
- kind of track, in §4.7.14.11.1
- kinds of elements, in §8.1.2
-
label
- element-attr for track, in §4.7.13
- attribute for HTMLTrackElement, in §4.7.13
- attribute for AudioTrack, in §4.7.14.10.1
- attribute for VideoTrack, in §4.7.14.10.1
- attribute for TextTrack, in §4.7.14.11.5
- (element), in §4.10.4
- element-attr for optgroup, in §4.10.9
- attribute for HTMLOptGroupElement, in §4.10.9
- element-attr for option, in §4.10.10
- definition of, in §4.10.10
- attribute for HTMLOptionElement, in §4.10.10
- element-attr for menu, in §4.11.3
- attribute for HTMLMenuElement, in §4.11.3
- element-attr for menuitem, in §4.11.4
- attribute for HTMLMenuItemElement, in §4.11.4
- Label, in §4.11.6.1
- labelable, in §4.10.2
- labelable element, in §4.10.2
- labelable elements, in §4.10.2
- labeled control, in §4.10.4
- label of a track, in §4.7.14.11.1
- labels, in §4.10.4
- lack scripting support, in §2.2.1
-
lang
- element-attr for global, in §3.2.5.3
- element-attr for xml, in §3.2.5.3
-
language
- definition of, in §3.2.5.3
- attribute for AudioTrack, in §4.7.14.10.1
- attribute for VideoTrack, in §4.7.14.10.1
- attribute for TextTrack, in §4.7.14.11.5
- attribute for NavigatorLanguage, in §7.6.1.2
- element-attr for script, in §11.2
- languagechange, in §Unnumbered section
- language of a text track, in §4.7.14.11.1
- languages, in §7.6.1.2
- lastModified, in §3.1.2
- last selected source, in §4.7.5
- latest entry, in §6.6.1
- latin, in §4.10.19.7
- Latin Name, in §4.10.19.7
- latin-name, in §4.10.19.7
- Latin Prose, in §4.10.19.7
- latin-prose, in §4.10.19.7
- Latin Text, in §4.10.19.7
- Latin Verbatim, in §4.10.19.7
- leading and trailing whitespace stripped, in §2.4.1
-
left
- attr-value for marquee/direction, in §10.5.11
- state for marquee, in §11.3.2
- leftmargin, in §11.2
-
legacy caller operation
- dfn for embed, in §4.7.7
- dfn for object, in §4.7.8
- legend, in §4.10.17
-
length
- attribute for HTMLAllCollection, in §2.7.2.1
- attribute for HTMLOptionsCollection, in §2.7.2.3
- attribute for AudioTrackList, in §4.7.14.10.1
- attribute for VideoTrackList, in §4.7.14.10.1
- attribute for TextTrackList, in §4.7.14.11.5
- attribute for TextTrackCueList, in §4.7.14.11.5
- attribute for TimeRanges, in §4.7.14.13
- attribute for HTMLFormElement, in §4.10.3
- attribute for HTMLSelectElement, in §4.10.7
- attribute for DataTransferItemList, in §5.7.3.1
- attribute for Window, in §6.3.2
- attribute for History, in §6.6.2
- attribute for PluginArray, in §7.6.1.5
- attribute for MimeTypeArray, in §7.6.1.5
- attribute for Plugin, in §7.6.1.5
- li, in §4.4.7
- license, in §4.8.6.6
- limited-quirks mode, in §2.2.2
- limited to numbers greater than zero, in §2.7.1
- limited to only known values, in §2.7.1
- limited to only non-negative numbers, in §2.7.1
- limited to only non-negative numbers greater than zero, in §2.7.1
- lineno, in §7.1.3.8.2
- :link, in §4.15.2
-
link
- (element), in §4.2.4
- value for dropEffect, in §5.7.3
- value for effectAllowed, in §5.7.3
- value for drag, in §5.7.5
- definition of, in §5.7.8
- element-attr for body, in §11.2
- attribute for HTMLBodyElement, in §11.3.5
- linkColor, in §11.3.5
- linkMove, in §5.7.3
- links, in §3.1.3
- links to external resources, in §4.8.1
- link type, in §4.8.6
- link types, in §4.8.6
-
list
- element-attr for input, in §4.10.5.3.9
- attribute for HTMLInputElement, in §4.10.5.4
- Listed element, in §4.10.2
- Listed elements, in §4.10.2
- listing, in §11.2
- list of active formatting elements, in §8.2.3.3
- list of active timers, in §7.4
- list of animation frame callbacks, in §7.8
- list of available images, in §4.7.5
- list of cues, in §4.7.14.11.1
- list of cues of a text track, in §4.7.14.11.1
- list of dragged nodes, in §5.7.5
- list of newly introduced cues, in §4.7.14.8
- list of options, in §4.10.7
- list of pending master entries, in §11.3.4
- list of pending text tracks, in §4.7.14.11.1
- list of scripts that will execute in order as soon as possible, in §4.12.1.1
- list of scripts that will execute when the document has finished parsing, in §4.12.1.1
- list of text tracks, in §4.7.14.11.1
- list of the descendant browsing contexts, in §6.1.1
- live, in §2.1.4
-
load()
- (function), in §3.1.4
- method for HTMLMediaElement, in §4.7.14.5
-
load
- event for track, in §4.7.14.15
- event for global, in §Unnumbered section
- loaded, in §4.7.14.11.1
- LOADED, in §4.7.13
- loadeddata, in §4.7.14.15
- loadedmetadata, in §4.7.14.15
- loadend, in §Unnumbered section
- LOADING, in §4.7.13
-
loading
- enum-value for DocumentReadyState, in §3.1.1
- state for track, in §4.7.14.11.1
- "loading", in §3.1.1
-
loadstart
- event for media, in §4.7.14.15
- event for global, in §Unnumbered section
- load(url), in §3.1.4
- Local Date and Time, in §4.10.5.1.11
- Location, in §6.6.4
-
location
- attribute for Document, in §6.6.4
- attribute for Window, in §6.6.4
- locationbar, in §6.3.6
- Location-object navigate, in §6.6.4
- Location-object-setter navigate, in §6.6.4
- locked for focus, in §5.4.6
- locked for reset, in §4.10.3
-
loop
- element-attr for media, in §4.7.14.6
- attribute for HTMLMediaElement, in §4.7.14.6
- element-attr for marquee, in §11.3.2
- attribute for HTMLMarqueeElement, in §11.3.2
- loses focus, in §5.4.4
-
low
- element-attr for meter, in §4.10.15
- attribute for HTMLMeterElement, in §4.10.15
- low boundary, in §4.10.15
- lower-alpha, in §4.4.5
- lowercase ASCII hex digits, in §2.4.1
- lowercase ASCII letters, in §2.4.1
- lower-roman, in §4.4.5
-
lowsrc
- element-attr for img, in §11.2
- attribute for HTMLImageElement, in §11.3.5
-
ltr
- attr-value for global/dir, in §3.2.5.6
- state for dir, in §3.2.5.6
- LTR-specific, in §10.2
- machine-readable equivalent of the element’s contents, in §4.5.16
- Mail as body, in §4.10.22.3
- mailto:, in §2.2.2
- Mail with headers, in §4.10.22.3
-
main
- (element), in §4.4.13
- attr-value for commonTrack/kind, in §4.7.14.10.1
- main-desc, in §4.7.14.10.1
-
manifest
- element-attr for html, in §11.2
- definition of, in §11.3.4
-
manual
- value for scrollRestorationMode, in §6.6.1
- enum-value for ScrollRestoration, in §6.6.2
- "manual", in §6.6.2
- map, in §4.7.15
- maps to the dimension properties, in §10.2
- maps to the dimension property, in §10.2
- maps to the dimension property (ignoring zero), in §10.2
- maps to the pixel length property, in §10.2
- map to the dimension property (ignoring zero), in §10.2
-
marginHeight
- attribute for HTMLFrameElement, in §11.3.3
- attribute for HTMLIFrameElement, in §11.3.5
-
marginheight
- element-attr for body, in §11.2
- element-attr for iframe, in §11.2
- margintop, in §11.2
-
marginwidth
- element-attr for body, in §11.2
- element-attr for iframe, in §11.2
-
marginWidth
- attribute for HTMLFrameElement, in §11.3.3
- attribute for HTMLIFrameElement, in §11.3.5
- mark, in §4.5.25
- markers, in §8.2.3.3
- marquee, in §11.3.2
- marquee current loop index, in §11.3.2
- marquee loop count, in §11.3.2
- marquee scroll distance, in §11.3.2
- marquee scroll interval, in §11.3.2
- master, in §11.3.4
- master entries, in §11.3.4
- matches a drag data store, in §5.7.8
- matches a fallback namespace, in §11.3.4
- matches the environment, in §2.4.10
- matches the fallback namespace, in §11.3.4
- match service worker registration, in §2.2.2
- match the environment, in §2.4.10
- MathML namespace, in §2.8
- MathML text integration point, in §8.2.5
- matured, in §6.7.1
-
max
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.3.7
- element-attr for progress, in §4.10.14
- attribute for HTMLProgressElement, in §4.10.14
- element-attr for meter, in §4.10.15
- attribute for HTMLMeterElement, in §4.10.15
- maximum, in §4.10.5.3.7
- maximum allowed value length, in §4.10.19.3
-
maximum value
- dfn for progress, in §4.10.14
- dfn for meter, in §4.10.15
-
maxLength
- attribute for HTMLInputElement, in §4.10.5
- attribute for HTMLTextAreaElement, in §4.10.11
-
maxlength
- element-attr for input, in §4.10.5.3.1
- element-attr for textarea, in §4.10.11
- "maybe", in §4.7.14
-
maybe
- enum-value for CanPlayTypeResult, in §4.7.14
- definition of, in §4.7.14.3
-
media
- element-attr for link, in §4.2.4
- attribute for HTMLLinkElement, in §4.2.4
- element-attr for style, in §4.2.6
- attribute for HTMLStyleElement, in §4.2.6
- element-attr for source, in §4.7.4
- media data, in §4.7.14
- media data processing steps list, in §4.7.14.5
- media element, in §4.7.14
- media element attributes, in §4.7.14
- media element event task source, in §4.7.14
- media element load algorithm, in §4.7.14.5
- media elements, in §4.7.14
- MEDIA_ERR_ABORTED, in §4.7.14.1
- MEDIA_ERR_DECODE, in §4.7.14.1
- MEDIA_ERR_NETWORK, in §4.7.14.1
- MediaError, in §4.7.14.1
- MEDIA_ERR_SRC_NOT_SUPPORTED, in §4.7.14.1
- media provider object, in §4.7.14.2
- media resource, in §4.7.14
- media-resource-specific text track, in §4.7.14.11.2
- media timeline, in §4.7.14.6
- media type, in §2.1.1
-
menu
- attr-value for button/type, in §4.10.6
- element-attr for button, in §4.10.6
- attribute for HTMLButtonElement, in §4.10.6
- (element), in §4.11.3
- Menu, in §4.10.6
- menubar, in §6.3.6
- menu button, in §4.10.6
- menu command, in §4.11.6.5
- menu construct, in §4.11.3
- menuitem, in §4.11.4
- menu item constructs, in §4.11.3
- menu item generator, in §4.11.3
-
message
- attribute for ErrorEvent, in §7.1.3.8.2
- event for global, in §Unnumbered section
- meta, in §4.2.5
-
Metadata
- state for track, in §4.7.13
- state for media, in §4.7.14.5
- "metadata", in §4.7.14.11.5
-
metadata
- attr-value for track/kind, in §4.7.13
- value for HTMLMediaElement/preload, in §4.7.14.5
- definition of, in §4.7.14.11.1
- enum-value for TextTrackKind, in §4.7.14.11.5
- metadata content, in §3.2.4.2.1
- metadata names, in §4.2.5.2
- meter, in §4.10.15
-
method
- element-attr for form, in §4.10.19.6
- dfn for forms, in §4.10.19.6
- attribute for HTMLFormElement, in §4.10.19.6
-
methods
- element-attr for a, in §11.2
- element-attr for link, in §11.2
- microtask, in §7.1.4.2
- microtask checkpoints, in §7.1.4.2
- microtask queue, in §7.1.4.2
- microtask task source, in §7.1.4.2
- mime type, in §2.1.1
- MimeType, in §7.6.1.5
- MimeTypeArray, in §7.6.1.5
- mimeTypes, in §7.6.1.5
- mime types, in §2.1.1
-
min
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.3.7
- element-attr for meter, in §4.10.15
- attribute for HTMLMeterElement, in §4.10.15
- minimum, in §4.10.5.3.7
- minimum allowed value length, in §4.10.19.4
- minimum value, in §4.10.15
-
minLength
- attribute for HTMLInputElement, in §4.10.5
- attribute for HTMLTextAreaElement, in §4.10.11
-
minlength
- element-attr for input, in §4.10.5.3.1
- element-attr for textarea, in §4.10.11
- missing value default, in §2.4.3
- mode, in §4.7.14.11.5
- Month, in §4.10.5.1.8
-
month
- definition of, in §2.4.5.1
- attr-value for input/type, in §4.10.5
- most appropriate application cache, in §11.3.4
-
move
- value for dropEffect, in §5.7.3
- value for effectAllowed, in §5.7.3
- value for drag, in §5.7.5
- definition of, in §5.7.8
- multicol, in §11.2
- multipart/form-data, in §4.10.19.6
- multipart/form-data boundary string, in §4.10.22.7
- multipart/form-data encoding algorithm, in §4.10.22.7
-
multiple
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.3.5
- element-attr for select, in §4.10.7
- attribute for HTMLSelectElement, in §4.10.7
- mutable, in §4.10.18.2
- Mutate action URL, in §4.10.22.3
- mutation observers, in §2.2.2
-
muted
- definition of, in §4.7.14.12
- attribute for HTMLMediaElement, in §4.7.14.12
- element-attr for media, in §4.7.14.12
- muted errors, in §7.1.3.1
- mute iframe load, in §4.7.6
-
name
- event for global, in §2.2.2
- element-attr for meta, in §4.2.5
- attribute for HTMLMetaElement, in §4.2.5
- element-attr for iframe, in §4.7.6
- attribute for HTMLIFrameElement, in §4.7.6
- element-attr for object, in §4.7.8
- element-attr for param, in §4.7.9
- attribute for HTMLParamElement, in §4.7.9
- element-attr for map, in §4.7.15
- attribute for HTMLMapElement, in §4.7.15
- element-attr for form, in §4.10.3
- attribute for HTMLFormElement, in §4.10.3
- element-attr for formelements, label, input, button, select, textarea, keygen, output, fieldset, in §4.10.19.1
- attribute for HTMLInputElement, HTMLButtonElement, HTMLSelectElement, HTMLTextAreaElement, HTMLKeygenElement, HTMLOutputElement, HTMLFieldSetElement, in §4.10.19.1
- attribute for Window, in §6.3.1
- attribute for Plugin, in §7.6.1.5
- definition of, in §8.1.2.3
- element-attr for a, in §11.2
- element-attr for embed, in §11.2
- element-attr for img, in §11.2
- element-attr for option, in §11.2
- attribute for HTMLAppletElement, in §11.3.1
- element-attr for frame, in §11.3.3
- attribute for HTMLFrameElement, in §11.3.3
- attribute for HTMLAnchorElement, in §11.3.5
- attribute for HTMLEmbedElement, in §11.3.5
- attribute for HTMLImageElement, in §11.3.5
- named color, in §2.2.2
- named colors, in §2.2.2
- Named elements, in §3.1.3
- named for the all collection, in §2.7.2.1
-
namedItem(name)
- method for HTMLAllCollection, in §2.7.2.1
- method for HTMLFormControlsCollection, in §2.7.2.2
- method for HTMLSelectElement, in §4.10.7
- method for PluginArray, in §7.6.1.5
- method for MimeTypeArray, in §7.6.1.5
- method for Plugin, in §7.6.1.5
- Named objects, in §6.3.3
- names, in §8.1.2.3
- naturalHeight, in §4.7.5
- naturalWidth, in §4.7.5
- nav, in §4.3.4
- navigate, in §6.7.1
- navigated, in §6.7.1
- navigating, in §6.7.1
- navigating a browsing context, in §6.7.1
- navigation, in §6.7.1
- navigation algorithm, in §6.7.1
- Navigator, in §7.6.1
- navigator, in §7.6.1
- NavigatorContentUtils, in §7.6.1.3
- NavigatorCookies, in §7.6.1.4
- NavigatorID, in §7.6.1.1
- NavigatorLanguage, in §7.6.1.2
- navigator.onLine, in §6.7.13
- NavigatorOnLine, in §6.7.13
- NavigatorPlugins, in §7.6.1.5
- nearest activatable element, in §5.3
- nearest ancestor autofocus scoping root element, in §4.10.19.6.1
- nested browsing context, in §6.1.1
- nested browsing contexts, in §6.1.1
- nested through, in §6.1.1
- NETWORK_EMPTY, in §4.7.14.4
- NETWORK_IDLE, in §4.7.14.4
- networking task source, in §7.1.4.3
- NETWORK_LOADING, in §4.7.14.4
- NETWORK_NO_SOURCE, in §4.7.14.4
- networkState, in §4.7.14.4
- new, in §2.7.4
- newer, in §11.3.4
- newest, in §11.3.4
- newURL, in §6.7.10.3
- next, in §4.8.6.12.1
- nextid, in §11.2
- next input character, in §8.2.2.5
- next token, in §8.2.5
- nobr, in §11.2
- No CORS, in §2.6.6
- node A is removed, in §2.1.3
- noembed, in §11.2
- nofollow, in §4.8.6.7
- noframes, in §11.2
- nohref, in §11.2
- noHref, in §11.3.5
- "non-blocking", in §4.12.1.1
-
nonce
- element-attr for style, in §4.2.6
- attribute for HTMLStyleElement, in §4.2.6
- element-attr for script, in §4.12.1
- attribute for HTMLScriptElement, in §4.12.1
-
none
- value for HTMLMediaElement/preload, in §4.7.14.5
- context for canvas, in §4.12.4
- value for dropEffect, in §5.7.3
- value for effectAllowed, in §5.7.3
- value for drag, in §5.7.5
- None, in §4.7.14.5
- NONE, in §4.7.13
- no-quirks mode, in §2.2.2
- noreferrer, in §4.8.6.8
- noResize, in §11.3.3
- normal elements, in §8.1.2
- normalized TimeRanges object, in §4.7.14.13
- normalize the source densities, in §4.7.5
- noscript, in §4.12.2
- noShade, in §11.3.5
- noshade, in §11.2
-
not handled
- dfn for script, in §7.1.3.8
- dfn for promise, in §7.1.3.9
- nothing, in §3.2.4.1
- notify about rejected promises, in §7.1.3.9
- not loaded, in §4.7.14.11.1
- no-translate, in §3.2.5.4
- not yet been loaded, in §4.7.14.11.1
- novalidate, in §4.10.19.6
- noValidate, in §4.10.19.6
- no-validate state, in §4.10.19.6
- nowrap, in §11.2
- noWrap, in §11.3.5
- number, in §4.10.5
- Number, in §4.10.5.1.12
- number of bytes downloaded, in §2.6.2
- number of child browsing contexts, in §6.3.2
- number of days in month month of year year, in §2.4.5
- numeric, in §4.10.19.7
- Numeric, in §4.10.19.7
-
object
- (element), in §4.7.8
- attribute for HTMLAppletElement, in §11.3.1
- _object, in §11.3.1
- object properties, in §2.1
- object property, in §2.1
- OBSOLETE, in §11.3.4.8
- obsolete, in §11.3.4
- obsolete permitted DOCTYPE, in §8.1.1
- obsolete permitted DOCTYPE string, in §8.1.1
- obtain, in §4.2.4
- obtain a physical form, in §10.8
- obtain the resource, in §4.2.4
-
off
- attr-value for form/autocomplete, in §4.10.3
- state for form/autocomplete, in §4.10.3
- attr-value for forms/autocomplete, in §4.10.19.8.1
- official playback position, in §4.7.14.6
- offline, in §Unnumbered section
- ol, in §4.4.5
- oldURL, in §6.7.10.3
- omitted, in §8.1.2.4
-
on
- attr-value for form/autocomplete, in §4.10.3
- state for form/autocomplete, in §4.10.3
- attr-value for forms/autocomplete, in §4.10.19.8.1
- onabort, in §7.1.5.2
-
onaddtrack
- attribute for AudioTrackList, in §4.7.14.10.1
- attribute for VideoTrackList, in §4.7.14.10.1
- attribute for MediaTrackList, in §4.7.14.10.1
- attribute for TextTrackList, in §4.7.14.11.8
- onafterprint, in §7.1.5.2
- onbeforeprint, in §7.1.5.2
-
onbeforeunload
- attribute for OnBeforeUnloadEventHandler, in §7.1.5.2
- attribute for WindowEventHandlers, in §7.1.5.2.1
- onblur, in §7.1.5.2
- onbounce, in §11.3.2
- oncached, in §11.3.4.8
- oncancel, in §7.1.5.2
- oncanplay, in §7.1.5.2
- oncanplaythrough, in §7.1.5.2
-
onchange
- attribute for AudioTrackList, in §4.7.14.10.1
- attribute for VideoTrackList, in §4.7.14.10.1
- attribute for MediaTrackList, in §4.7.14.10.1
- attribute for TextTrackList, in §4.7.14.11.8
- attribute for GlobalEventHandlers, in §7.1.5.2
- onchecking, in §11.3.4.8
- onclick, in §7.1.5.2
- onclose, in §7.1.5.2
- oncontextmenu, in §7.1.5.2
- oncopy, in §7.1.5.2
-
oncuechange
- attribute for TextTrack, in §4.7.14.11.8
- attribute for GlobalEventHandlers, in §7.1.5.2
- oncut, in §7.1.5.2
- ondblclick, in §7.1.5.2
- ondownloading, in §11.3.4.8
- ondrag, in §7.1.5.2
- ondragend, in §7.1.5.2
- ondragenter, in §7.1.5.2
- ondragexit, in §7.1.5.2
- ondragleave, in §7.1.5.2
- ondragover, in §7.1.5.2
- ondragstart, in §7.1.5.2
- ondrop, in §7.1.5.2
- ondurationchange, in §7.1.5.2
- onemptied, in §7.1.5.2
- onended, in §7.1.5.2
- onenter, in §4.7.14.11.8
- one permitted sandboxed navigator, in §6.5
-
onerror
- attribute for GlobalEventHandlers, in §7.1.5.2
- attribute for ApplicationCache, in §11.3.4.8
- onexit, in §4.7.14.11.8
- onfinish, in §11.3.2
- onfocus, in §7.1.5.2
- onhashchange, in §7.1.5.2
- oninput, in §7.1.5.2
- oninvalid, in §7.1.5.2
- onkeydown, in §7.1.5.2
- onkeypress, in §7.1.5.2
- onkeyup, in §7.1.5.2
- onlanguagechange, in §7.1.5.2
- online, in §Unnumbered section
- onLine, in §6.7.13
- online safelist, in §11.3.4.1
- online safelist namespaces, in §11.3.4
- online safelist wildcard flag, in §11.3.4
- onload, in §7.1.5.2
- onloadeddata, in §7.1.5.2
- onloadedmetadata, in §7.1.5.2
- onloadstart, in §7.1.5.2
- only if border is not equivalent to zero, in §10.3.9
- onmessage, in §7.1.5.2
- onmousedown, in §7.1.5.2
- onmouseenter, in §7.1.5.2
- onmouseleave, in §7.1.5.2
- onmousemove, in §7.1.5.2
- onmouseout, in §7.1.5.2
- onmouseover, in §7.1.5.2
- onmouseup, in §7.1.5.2
- onnoupdate, in §11.3.4.8
- onobsolete, in §11.3.4.8
- onoffline, in §7.1.5.2
- ononline, in §7.1.5.2
- onpagehide, in §7.1.5.2
- onpageshow, in §7.1.5.2
- onpaste, in §7.1.5.2
- onpause, in §7.1.5.2
- onplay, in §7.1.5.2
- onplaying, in §7.1.5.2
- onpopstate, in §7.1.5.2
-
onprogress
- attribute for GlobalEventHandlers, in §7.1.5.2
- attribute for ApplicationCache, in §11.3.4.8
- onratechange, in §7.1.5.2
-
onreadystatechange
- attribute for Document, in §3.1.1
- definition of, in §7.1.5.2
- onrejectionhandled, in §7.1.5.2
-
onremovetrack
- attribute for AudioTrackList, in §4.7.14.10.1
- attribute for VideoTrackList, in §4.7.14.10.1
- attribute for MediaTrackList, in §4.7.14.10.1
- attribute for TextTrackList, in §4.7.14.11.8
- onreset, in §7.1.5.2
- onresize, in §7.1.5.2
- onscroll, in §7.1.5.2
- onseeked, in §7.1.5.2
- onseeking, in §7.1.5.2
- onselect, in §7.1.5.2
- onshow, in §7.1.5.2
- onstalled, in §7.1.5.2
- onstart, in §11.3.2
- onstorage, in §7.1.5.2
- onsubmit, in §7.1.5.2
- onsuspend, in §7.1.5.2
- ontimeupdate, in §7.1.5.2
- ontoggle, in §7.1.5.2
- onunhandledrejection, in §7.1.5.2
- onunload, in §7.1.5.2
- onupdateready, in §11.3.4.8
- onvolumechange, in §7.1.5.2
- onwaiting, in §7.1.5.2
- onwheel, in §7.1.5.2
- opaque origin, in §6.4
-
open
- element-attr for details, in §4.11.1
- attribute for HTMLDetailsElement, in §4.11.1
- event for global, in §Unnumbered section
-
open()
- method for Window, in §6.3.1
- method for Document, in §7.3.1
-
opener
- definition of, in §6.1.2.1
- attribute for Window, in §6.3
- opener browsing context, in §6.1.2
- open(type), in §7.3.1
- open(type, replace), in §7.3.1
- open(url, name, features), in §7.3.1
- open(url, name, features, replace), in §7.3.1
- optgroup, in §4.10.9
-
optimum
- element-attr for meter, in §4.10.15
- attribute for HTMLMeterElement, in §4.10.15
- optimum point, in §4.10.15
- optimum value, in §4.10.15
- option, in §4.10.10
- :optional, in §4.15.2
- optionally truncate a simple dialog string, in §7.5.1
- optionally truncated, in §7.5.1
- optionally truncating, in §7.5.1
- optional start and end tags, in §8.1.2.4
-
options
- attribute for HTMLSelectElement, in §4.10.7
- attribute for HTMLDataListElement, in §4.10.8
- Option(text, value, defaultSelected, selected), in §4.10.10
- ordered set of unique space-separated tokens, in §2.4.7
- ordinal value, in §4.4.7
- Ordinary, in §8.2.3.2
- or equivalent, in §2.6.1
-
origin
- attribute for HTMLHyperlinkElementUtils, in §4.8.3
- dfn for concept, in §6.4
- attribute for Location, in §6.6.4
- original insertion mode, in §8.2.3.1
- origin-clean, in §4.12.4
- origin domain, in §6.4
- origin host, in §6.4
- origin port, in §6.4
- origins, in §6.4
- origin scheme, in §6.4
- Other link types, in §4.8.6.13
- outline, in §4.3.10.1
- outline depth, in §4.3.10.1
- :out-of-range, in §4.15.2
- output, in §4.10.13
- outstanding rejected promises weak set, in §7.1.3.1
- overridden reload, in §3.1
- override URL, in §6.7.1
- owner, in §5.4.2
- p, in §4.4.1
- pagehide, in §Unnumbered section
- pageshow, in §Unnumbered section
- page showing, in §6.7.11
- PageTransitionEvent, in §6.7.10.4
- PageTransitionEvent(type), in §6.7.10.4
- PageTransitionEvent(type, eventInitDict), in §6.7.10.4
- palpable content, in §3.2.4.2.8
- paragraph, in §3.2.4.4
- paragraphing, in §3.2.4.4
- paragraphs, in §3.2.4.4
- param, in §4.7.9
- parameter, in §4.7.9
- parent, in §6.1.1.1
- parent browsing context, in §6.1.1
- parse, in §2.5.2
- parse a date component, in §2.4.5.2
- parse a date or time string, in §2.4.5.10
- parse a date string, in §2.4.5.2
- parse a duration string, in §2.4.5.9
- parse a floating date and time string, in §2.4.5.5
- parse a global date and time string, in §2.4.5.7
- parse a manifest, in §11.3.4.1
- parse a month component, in §2.4.5.1
- parse a month string, in §2.4.5.1
- parse a sandboxing directive, in §6.5
- parse a sizes attribute, in §4.7.5
- parse a srcset attribute, in §4.7.5
- parse a time component, in §2.4.5.4
- parse a time string, in §2.4.5.4
- parse a time-zone offset component, in §2.4.5.6
- parse a time-zone offset string, in §2.4.5.6
- parse a URL, in §2.5.2
- parse a week string, in §2.4.5.8
- parse a yearless date component, in §2.4.5.3
- parse a yearless date string, in §2.4.5.3
- parse child’s sizes attribute, in §4.7.5
- parse child’s srcset attribute, in §4.7.5
- parsed as a CSS <color> value, in §2.2.2
- parse error, in §8.2
- parse errors, in §8.2
- parse it as an integer, in §2.4.4.1
- "parser-inserted", in §4.12.1.1
- parser pause flag, in §8.2.1
- parse that attribute’s value, in §2.4.4.2
- parse the sandboxing directive, in §6.5
- parse token as an integer, in §2.4.4.1
- parsing, in §2.5.2
- parsing a date, in §2.4.5.2
- parsing a date and time, in §2.4.5.7
- parsing a date string, in §2.4.5.2
- parsing a duration string, in §2.4.5.9
- parsing a floating date and time, in §2.4.5.5
- parsing a floating date and time string, in §2.4.5.5
- parsing a month, in §2.4.5.1
- parsing a month string, in §2.4.5.1
- parsing a time, in §2.4.5.4
- parsing a time string, in §2.4.5.4
- parsing a time-zone offset string, in §2.4.5.6
- parsing a week, in §2.4.5.8
- parsing a week string, in §2.4.5.8
- parsing a yearless date string, in §2.4.5.3
- parsing of relative urls, in §2.5.2
- parsing relative urls, in §2.5.2
- partially available, in §4.7.5
- Partially available, in §4.7.5
- passing its URL or data to an external software package, in §6.7.1
- Password, in §4.10.5.1.6
-
password
- attribute for HTMLHyperlinkElementUtils, in §4.8.3
- attr-value for input/type, in §4.10.5
- paste, in §Unnumbered section
- past names map, in §4.10.3
- Path components, in §4.10.5.1.17
-
pathname
- attribute for HTMLHyperlinkElementUtils, in §4.8.3
- attribute for Location, in §6.6.4
-
pattern
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.3.6
- patternMismatch, in §4.10.21.3
- pause(), in §4.7.14.8
- Pause, in §7.1.4.2
-
pause
- event for media, in §4.7.14.15
- state for useragent, in §7.1.4.2
- paused, in §4.7.14.8
- paused for in-band content, in §4.7.14.8
- paused for user interaction, in §4.7.14.8
- pause-on-exit, in §4.7.14.11.1
- pauseOnExit, in §4.7.14.11.5
- pause-on-exit flag, in §4.7.14.11.1
- pending application cache download process tasks, in §11.3.4.2
- pending parsing-blocking script, in §4.12.1.1
- pending request, in §4.7.5
- pending table character tokens, in §8.2.5.4.9
- pending text track change notification flag, in §4.7.14.11.1
- perform a microtask checkpoint, in §7.1.4.2
- perform automatic text track selection, in §4.7.14.11.3
- performing a microtask checkpoint flag, in §7.1.4.1
- performs a microtask checkpoint, in §7.1.4.2
- persisted, in §6.7.10.4
- personalbar, in §6.3.6
- phrasing content, in §3.2.4.2.5
- pick an encoding for a form, in §4.10.22.5
- picked, in §4.10.7
- picking an encoding for the form, in §4.10.22.5
- picture, in §4.7.3
- picture source, in §4.7.4
- picture source type, in §4.7.4
-
placeholder
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.3.10
- element-attr for textarea, in §4.10.11
- attribute for HTMLTextAreaElement, in §4.10.11
- placeholder label option, in §4.10.7
- plaintext, in §11.2
- plain text file, in §6.7.4
- planned navigation, in §4.10.22.3
- plan to navigate, in §4.10.22.3
- platform, in §7.6.1.1
- plausible languages, in §7.6.1.2
- play, in §4.7.14.15
- play(), in §4.7.14.8
- playback ended, in §4.7.14.8
- playback has ended, in §4.7.14.8
- playbackRate, in §4.7.14.8
- playback volume, in §4.7.14.12
- played, in §4.7.14.8
- playing, in §4.7.14.15
- Plugin, in §7.6.1.5
- plugin, in §2.1.5
- PluginArray, in §7.6.1.5
- plugin document, in §6.7.7
-
plugins
- definition of, in §2.1.5
- attribute for Document, in §3.1.3
- attribute for NavigatorPlugins, in §7.6.1.5
- poly, in §4.7.16
- polygon, in §4.7.16
- Polygon state, in §4.7.16
- polygon state, in §4.7.16
- popstate, in §Unnumbered section
- PopStateEvent, in §6.7.10.2
- PopStateEvent(type), in §6.7.10.2
- PopStateEvent(type, eventInitDict), in §6.7.10.2
- populate the list of pending text tracks, in §4.7.14.11.1
- popup menu, in §4.11.3
- popup sandboxing flag set, in §6.5
-
port
- attribute for HTMLHyperlinkElementUtils, in §4.8.3
- attribute for Location, in §6.6.4
- position, in §4.10.14
- possibly appropriate alternatives, in §5.7.4
- post, in §4.10.19.6
- POST, in §4.10.19.6
-
poster
- element-attr for video, in §4.7.10
- definition of, in §4.7.10
- poster frame, in §4.7.10
- Post to data:, in §4.10.22.3
- potentially active, in §4.7.7
- potentially playing, in §4.7.14.8
- practical concerns, in §2.2.1
- pragma-set default language, in §4.2.5.3
- pre, in §4.4.3
- pre-click activation steps, in §5.3
- prefer-online, in §11.3.4
- prefix match, in §2.3
- prefix match patterns, in §11.3.4
-
preload
- element-attr for media, in §4.7.14.5
- attribute for HTMLMediaElement, in §4.7.14.5
- prepare an event, in §4.7.14.8
- prepare a script, in §4.12.1.1
- prepared, in §4.12.1.1
- prepare to run script, in §7.1.3.4
- preparing, in §4.12.1.1
- prescan a byte stream to determine its encoding, in §8.2.2.2
- prescan the byte stream to determine its encoding, in §8.2.2.2
- presentational hints, in §10.2
-
preserve
- enum-value for SelectionMode, in §4.10.20
- enum for SelectionMode, in §4.10.20
- "preserve", in §4.10.20
- prev, in §4.8.6.12.2
- prevents content from creating new auxiliary browsing contexts, in §6.1.5
- previous target element, in §5.7.5
- primary control group, in §5.4.5
- print(), in §7.5.2
- printing steps, in §7.5.2
- print when loaded, in §7.5.2
-
probably
- enum-value for CanPlayTypeResult, in §4.7.14
- definition of, in §4.7.14.3
- "probably", in §4.7.14
- probablySupportsContext(contextId, arguments...), in §4.12.4
- probablySupportsContext(contextId, arguments), in §4.12.4
- proceed with that mechanism instead, in §6.7.1
- process an rtc element, in §4.5.13
- processing model for navigating across documents, in §6.7.1
- process the frame attributes, in §11.3.3
- process the iframe attributes, in §4.7.6
- process the resource appropriately, in §6.7.1
- Process the response, in §7.1.3.2
- product, in §7.6.1.1
-
profile
- element-attr for head, in §11.2
- attribute for HTMLHeadElement, in §11.3.5
-
progress
- event for media, in §4.7.14.15
- (element), in §4.10.14
- event for global, in §Unnumbered section
- proleptic Gregorian calendar, in §2.4.5
- proleptic-Gregorian date, in §2.4.5
- promise, in §7.1.3.9.2
- PromiseRejectionEvent, in §7.1.3.9.2
- PromiseRejectionEvent(type, eventInitDict), in §7.1.3.9.2
- prompt(), in §7.5.1
- prompt(message), in §7.5.1
- prompt(message, default), in §7.5.1
- prompt to unload, in §6.7.11
- prompt to unload a document, in §6.7.11
- Protected mode, in §5.7.2
-
protocol
- attribute for HTMLHyperlinkElementUtils, in §4.8.3
- attribute for Location, in §6.6.4
- proto-URL, in §7.6.1.3
- provides a paint source, in §2.2.2
- provides a stable state, in §7.1.4.2
- provide such information, in §4.9.1.1
- push onto the list of active formatting elements, in §8.2.3.3
- pushState(data, title), in §6.6.2
- pushState(data, title, url), in §6.6.2
- q, in §4.5.7
- queryCommandEnabled(), in §5.6.4
- queryCommandEnabled(commandId), in §3.1.1
- queryCommandIndeterm(), in §5.6.4
- queryCommandIndeterm(commandId), in §3.1.1
- queryCommandState(), in §5.6.4
- queryCommandState(commandId), in §3.1.1
- queryCommandSupported(), in §5.6.4
- queryCommandSupported(commandId), in §3.1.1
- queryCommandValue(), in §5.6.4
- queryCommandValue(commandId), in §3.1.1
- queue a microtask, in §7.1.4.2
- queue a post-load task, in §11.3.4.2
- queue a progress post-load task, in §11.3.4.2
- queue a task, in §7.1.4.1
- queued, in §7.1.4.2
- queues a task, in §7.1.4.1
- queue that task as a post-load task, in §11.3.4.2
- queuing, in §7.1.4.1
- quirks mode, in §2.2.2
-
radio
- attr-value for input/type, in §4.10.5
- attr-value for menuitem/type, in §4.11.4
- Radio, in §4.11.4
- Radio Button, in §4.10.5.1.16
- radio button group, in §4.10.5.1.16
-
radiogroup
- element-attr for menuitem, in §4.11.4
- attribute for HTMLMenuItemElement, in §4.11.4
- RadioNodeList, in §2.7.2.2
- range, in §4.10.5
- Range, in §4.10.5.1.13
- rangeOverflow, in §4.10.21.3
- rangeUnderflow, in §4.10.21.3
- rank, in §4.3.6
- rarely necessary, in §4.10.19.7
- ratechange, in §4.7.14.15
- raw text, in §8.1.2
- raw text elements, in §8.1.2
- raw value, in §4.10.11
- rb, in §4.5.11
- read errors, in §2.2.2
- readiness state, in §4.7.14.11.1
-
readonly
- element-attr for input, in §4.10.5.3.3
- element-attr for textarea, in §4.10.11
- :read-only, in §4.15.2
-
readOnly
- attribute for HTMLInputElement, in §4.10.5
- attribute for HTMLTextAreaElement, in §4.10.11
- Read-only mode, in §5.7.2
- :read-write, in §4.15.2
- Read/write mode, in §5.7.2
- ready, in §4.7.14.11.1
- ready for post-load tasks, in §8.2.6
-
readyState
- attribute for Document, in §3.1.2
- attribute for HTMLTrackElement, in §4.7.13
- attribute for HTMLMediaElement, in §4.7.14.7
- readystatechange, in §Unnumbered section
- "ready to be parser-executed", in §4.12.1.1
- realm execution context, in §7.1.3.1
- reason, in §7.1.3.9.2
- reassociateable, in §4.10.2
- Reassociateable element, in §4.10.2
- Reassociateable elements, in §4.10.2
- reconstruction of the active formatting element, in §8.2.3.3
- reconstruction of the active formatting elements, in §8.2.3.3
- reconstruct the active formatting element, in §8.2.3.3
- reconstruct the active formatting elements, in §8.2.3.3
- rect, in §4.7.16
- rectangle, in §4.7.16
- rectangle state, in §4.7.16
- Rectangle state, in §4.7.16
- rect state, in §4.7.16
- Rect state, in §4.7.16
- reentrant, in §8.2.1
- referrer, in §3.1.2
- referrer source, in §2.6.1
- reflect, in §2.7.1
- reflection, in §2.7.1
- refresh(), in §7.6.1.5
- refresh, in §4.2.5.3
- refresh(reload), in §7.6.1.5
- refused to allow the document to be unloaded, in §6.7.11
- refused to allow this document to be unloaded, in §6.7.11
- registerProtocolHandler(scheme, url, title), in §7.6.1.3
- register the name, in §4.2.5.2
- register the names, in §4.2.5.2
- reinitialise url, in §4.8.3
-
rel
- element-attr for link, in §4.2.4
- attribute for HTMLLinkElement, in §4.2.4
- attribute for HTMLAnchorElement, in §4.5.1
- attribute for HTMLAreaElement, in §4.7.16
- element-attr for a, area, links, in §4.8.2
- RelatedEvent, in §4.11.5.3
- RelatedEvent(type), in §4.11.5.3
- RelatedEvent(type, eventInitDict), in §4.11.5.3
- relatedTarget, in §4.11.5.3
-
releaseEvents()
- method for Document, in §11.3.5
- method for Window, in §11.3.5
- Relevant, in §7.1.3.5
- relevant application cache, in §11.3.4
- relevant child nodes, in §9.3
- relevant Document, in §6.6.4
- relevant global object, in §7.1.3.5.4
- relevant mutations, in §4.7.5
- relevant Realm, in §7.1.3.5.4
- relevant settings object, in §7.1.3.5.4
-
relList
- attribute for HTMLLinkElement, in §4.2.4
- attribute for HTMLAnchorElement, in §4.5.1
- attribute for HTMLAreaElement, in §4.7.16
- reload(), in §6.6.4
- reload override buffer, in §3.1
- reload override flag, in §3.1
- reload-triggered navigation, in §6.7.1
- removeCue(cue), in §4.7.14.11.5
- removed from, in §2.1.3
- removed from a document, in §2.1.3
-
remove(index)
- method for HTMLOptionsCollection, in §2.7.2.3
- method for HTMLSelectElement, in §4.10.7
- method for DataTransferItemList, in §5.7.3.1
- removetrack, in §4.7.14.15
- rendered legend, in §10.3.13
- reparsed, in §2.5.2
- replace(), in §6.6.4
- replaced element, in §2.2.2
- replacement enabled, in §6.7.10
- replacement must be enabled, in §6.7.10
- replaceState(data, title), in §6.6.2
- replaceState(data, title, url), in §6.6.2
- replace(url), in §6.6.4
- report an error, in §7.1.3.8
- report an exception, in §7.1.3.8.1
- reported MIME types, in §7.6.1.5
- report the error, in §7.1.3.8
- report the exception, in §7.1.3.8.1
- reportValidity()
- represent, in §3.2.2
- reprocess the iframe attributes, in §4.7.6
- requestAnimationFrame(), in §7.8
- requestAnimationFrame(callback), in §7.8
- :required, in §4.15.2
-
required
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.3.4
- definition of, in §4.10.5.3.4
- element-attr for select, in §4.10.7
- attribute for HTMLSelectElement, in §4.10.7
- element-attr for textarea, in §4.10.11
- attribute for HTMLTextAreaElement, in §4.10.11
-
reset
- attr-value for input/type, in §4.10.5
- attr-value for button/type, in §4.10.6
- definition of, in §4.10.23
- event for global, in §Unnumbered section
- reset(), in §4.10.3
- reset algorithm, in §4.10.23
- reset button, in §4.10.6
- Reset Button, in §4.10.5.1.20
- resettable, in §4.10.2
- Resettable element, in §4.10.2
- Resettable elements, in §4.10.2
- reset the form owner, in §4.10.18.3
- reset the insertion mode appropriately, in §8.2.3.1
-
resource
- dfn for http, in §2.1.1
- definition of, in §4.7.14
- resource fetch algorithm, in §4.7.14.5
- resource selection algorithm, in §4.7.14.5
- responsible browsing context, in §7.1.3.1
- responsible document, in §7.1.3.1
- responsible event loop, in §7.1.3.1
- restart the animation, in §10.4.2
- restore persisted user state, in §6.7.10.1
- restrictions, in §8.1.2.6
- restrictions on the contents of raw text and escapable raw text elements, in §8.1.2.6
- resulting URL record, in §2.5.2
- resulting URL records, in §2.5.2
- resulting URL string, in §2.5.2
-
returnValue
- attribute for BeforeUnloadEvent, in §6.7.11.1
- attribute for WindowModal, in §7.5.3
- return value, in §7.5.3
- return value origin, in §7.5.3
-
rev
- element-attr for a, link, links, in §4.2.4
- attribute for HTMLLinkElement, in §4.2.4
- attribute for HTMLAnchorElement, in §4.5.1
-
reversed
- element-attr for ol, in §4.4.5
- attribute for HTMLOListElement, in §4.4.5
- reverse link, in §4.2.4
- Reverse links, in §4.2.4
-
right
- attr-value for marquee/direction, in §10.5.11
- state for marquee, in §11.3.2
- rightmargin, in §11.2
- role, in §2.2.2
- root element, in §2.1.3
- root element of a Document object, in §2.1.3
- root elements, in §2.1.3
-
row
- attr-value for scope, in §4.9.10
- state for scope, in §4.9.10
- definition of, in §4.9.12
- rowgroup, in §4.9.10
-
row group
- state for scope, in §4.9.10
- definition of, in §4.9.12
- row group header, in §4.9.12.2
- row groups, in §4.9.12
- row header, in §4.9.12.2
- rowIndex, in §4.9.8
-
rows
- attribute for HTMLTableElement, in §4.9.1
- attribute for HTMLTableSectionElement, in §4.9.5
- definition of, in §4.9.12
- element-attr for textarea, in §4.10.11
- attribute for HTMLTextAreaElement, in §4.10.11
- element-attr for frameset, in §11.3.3
- rowSpan, in §4.9.11
- rowspan, in §4.9.11
- rp, in §4.5.14
- rt, in §4.5.12
- rtc, in §4.5.13
-
rtl
- attr-value for global/dir, in §3.2.5.6
- state for dir, in §3.2.5.6
- ruby, in §4.5.10
- ruby annotation container, in §4.5.10
- ruby base container, in §4.5.10
- ruby bases, in §4.5.10
- ruby segment, in §4.5.10
- ruby text annotations, in §4.5.10
- ruby text container, in §4.5.10
-
rules
- element-attr for table, in §11.2
- attribute for HTMLTableElement, in §11.3.5
- rules for constructing the chapter tree from a text track, in §4.7.14.11.7
- rules for distinguishing if a resource is text or binary, in §2.6.4
- rules for extracting the chapter title, in §4.7.14.11.1
- rules for interpreting WebVTT cue text, in §2.2.2
- rules for parsing a hash-name reference, in §2.4.9
- rules for parsing a legacy color value, in §2.4.6
- rules for parsing a legacy font size, in §10.3.4
- rules for parsing a list of dimensions, in §2.4.4.7
- rules for parsing a list of floating-point numbers, in §2.4.4.6
- rules for parsing dimension values, in §2.4.4.4
- rules for parsing floating-point number values, in §2.4.4.3
- rules for parsing integer, in §2.4.4.1
- rules for parsing integers, in §2.4.4.1
- rules for parsing manifests, in §11.3.4.1
- rules for parsing non-negative integers, in §2.4.4.2
- rules for parsing non-zero dimension values, in §2.4.4.5
- rules for parsing signed integers, in §2.4.4.1
- rules for parsing simple color values, in §2.4.6
- rules for serializing simple color values, in §2.4.6
- rules for sniffing images specifically, in §2.6.4
- rules for updating the display of WebVTT text tracks, in §2.2.2
- rules for updating the text track rendering, in §4.7.14.11.1
- run a classic script, in §7.1.3.4
- run authentic click activation steps, in §5.3
- run canceled activation steps, in §5.3
- run CSS animations and send events, in §7.1.4.2
- running script, in §7.1.3.4
- running synthetic click activation steps, in §5.3
- running the classic script, in §7.1.3.4
- run post-click activation steps, in §5.3
- run pre-click activation steps, in §5.3
- runs, in §4.7.14.5
- run synthetic click activation steps, in §5.3
- run the animation frame callbacks, in §7.8
- run the classic script, in §7.1.3.4
- run the fullscreen rendering steps, in §7.1.4.2
- run the global script clean-up jobs, in §7.1.3.4
- Runtime script errors, in §7.1.3.8
- s, in §4.5.5
- safelisted schemes, in §7.6.1.3
- salvageable, in §6.7.11
- same origin, in §6.4
- same origin-domain, in §6.4
- samp, in §4.5.19
-
sandbox
- element-attr for iframe, in §4.7.6
- attribute for HTMLIFrameElement, in §4.7.6
- sandbox cookies, in §3.1.2
- sandboxed automatic features browsing context flag, in §6.5
- sandboxed auxiliary navigation browsing context flag, in §6.5
- sandboxed document.domain browsing context flag, in §6.5
- sandboxed forms browsing context flag, in §6.5
- sandboxed fullscreen browsing context flag, in §6.5
- sandboxed into a unique origin, in §6.5
- sandboxed modals flag, in §6.5
- sandboxed navigation browsing context flag, in §6.5
- sandboxed origin browsing context flag, in §6.5
- sandboxed plugins browsing context flag, in §6.5
- sandboxed pointer lock browsing context flag, in §6.5
- sandboxed scripts browsing context flag, in §6.5
- sandboxed storage area URLs flag, in §6.5
- sandboxed top-level navigation browsing context flag, in §6.5
- sandboxing flag set, in §6.5
- sandbox propagates to auxiliary browsing contexts flag, in §6.5
- satisfies its constraints, in §4.10.21.1
- satisfy its constraints, in §4.10.21.1
- satisfy their constraints, in §4.10.21.1
-
scheme
- element-attr for meta, in §11.2
- attribute for HTMLMetaElement, in §11.3.5
-
scope
- element-attr for th, in §4.9.10
- attribute for HTMLTableHeaderCellElement, in §4.9.10
- element-attr for td, in §11.2
-
script
- (element), in §4.12.1
- dfn for concept, in §7.1.3.1
- script-closable, in §6.3.1
- script content restrictions, in §4.12.1.3
- script-created parser, in §7.3.1
- script documentation, in §4.12.1.4
- scripting, in §7.1.3.1
- scripting flag, in §8.2.3.5
- Scripting is disabled, in §7.1.2
- Scripting is disabled for a node, in §7.1.2
- scripting is enabled, in §7.1.2
- Scripting is enabled for a node, in §7.1.2
- scripting was enabled, in §7.1.2
- scripting was enabled or not, in §8.2.3.5
- script nesting level, in §8.2.1
-
scripts
- attribute for Document, in §3.1.3
- dfn for concept, in §7.1.3.1
- Script-supporting element, in §3.2.4.2.9
- Script-supporting elements, in §3.2.4.2.9
-
scroll
- attr-value for marquee/behavior, in §11.3.2
- state for marquee/behavior, in §11.3.2
- scrollamount, in §11.3.2
- scrollAmount, in §11.3.2
- scrollbars, in §6.3.6
- scrolldelay, in §11.3.2
- scrollDelay, in §11.3.2
-
scrolling
- element-attr for iframe, in §11.2
- attribute for HTMLFrameElement, in §11.3.3
- attribute for HTMLIFrameElement, in §11.3.5
- scrollRestoration, in §6.6.2
- scroll restoration mode, in §6.6.1
- scroll to the fragment identifier, in §6.7.9
- Search, in §4.10.5.1.2
-
search
- attribute for HTMLHyperlinkElementUtils, in §4.8.3
- attr-value for link/type, in §4.8.6.9
- attr-value for input/type, in §4.10.5
- attribute for Location, in §6.6.4
- second administrative level, in §4.10.19.8.1
-
section
- (element), in §4.3.3
- definition of, in §4.3.10.1
- sectioning content, in §3.2.4.2.3
- sectioning roots, in §4.3.10
- sectionRowIndex, in §4.9.8
- secured, in §2.1.5
- Sec-WebSocket-Protocol, in §2.2.2
- seek, in §4.7.14.9
- seekable, in §4.7.14.9
- seeked, in §4.7.14.15
-
seeking
- attribute for HTMLMediaElement, in §4.7.14.9
- event for media, in §4.7.14.15
- segmentation and categorization of content of a ruby, in §4.5.10
- "select", in §4.10.20
-
select
- (element), in §4.10.7
- enum-value for SelectionMode, in §4.10.20
- enum for SelectionMode, in §4.10.20
- event for global, in §Unnumbered section
- select(), in §4.10.20
- select an application cache, in §11.3.4
- select an image source, in §4.7.5
-
selected
- attribute for VideoTrack, in §4.7.14.10.1
- element-attr for option, in §4.10.10
- attribute for HTMLOptionElement, in §4.10.10
- selected coordinate, in §4.10.5.1.19
- selected files, in §4.10.5.1.17
-
selectedIndex
- attribute for HTMLOptionsCollection, in §2.7.2.3
- attribute for VideoTrackList, in §4.7.14.10.1
- attribute for HTMLSelectElement, in §4.10.7
- selectedness, in §4.10.10
- selectedOptions, in §4.10.7
- selecting an image source, in §4.7.5
- selectionDirection, in §4.10.20
- selectionEnd, in §4.10.20
- selectionStart, in §4.10.20
- self, in §6.3
- self-closing flag, in §8.2.4
- send a signal, in §11.3.4.8
- send a WebSocket Message, in §2.2.2
- sends a signal, in §11.3.4.8
- send select update notifications, in §4.10.7
- Separators, in §4.11.3
- sequential focus navigation, in §5.4.5
- sequential focus navigation order, in §5.4.5
- sequential focus navigation starting point, in §5.4.5
- sequential navigation search algorithm, in §5.4.5
- session history, in §6.6.1
- session history document visibility change steps, in §6.7.10
- session history entry, in §6.6.1
- session history event loop, in §6.6.2
- session history traversal, in §6.7.10
- session history traversal queue, in §6.6.2
- set-cookie, in §4.2.5.3
- setCustomValidity(), in §4.10.21.3
- setCustomValidity(error), in §4.10.21.3
- setData(format, data), in §5.7.3
- setDragImage(image, x, y), in §5.7.3
- setInterval(handler, timeout, arguments...), in §7.4
- setInterval(handler, timeout, arguments), in §7.4
- set of comma-separated tokens, in §2.4.8
- set of scripts that will execute as soon as possible, in §4.12.1.1
- set of space-separated tokens, in §2.4.7
- setRangeText(), in §4.10.20
- setRangeText(replacement), in §4.10.20
- setRangeText(replacement, start, end), in §4.10.20
- setRangeText(replacement, start, end, selectionMode), in §4.10.20
- setSelectionRange(), in §4.10.20
- setSelectionRange(start, end), in §4.10.20
- setSelectionRange(start, end, direction), in §4.10.20
- set the document’s address, in §6.7.1
- set the frozen base URL, in §4.2.3
- set the url, in §4.8.3
- set the value of a new indexed property, in §4.10.7
- set the value of a new indexed property or set the value of an existing indexed property, in §2.7.2.3
- setTimeout(handler, timeout, arguments), in §7.4
- setTimeout(handler, timeout, arguments...), in §7.4
- setting, in §2.1.4
- settings object, in §7.1.3.1
- setting the document’s address, in §6.7.1
- set up a browsing context environment settings object, in §6.1.6
- Set up the request, in §7.1.3.2
-
shape
- element-attr for area, in §4.7.16
- attribute for HTMLAreaElement, in §4.7.16
- element-attr for a, in §11.2
- attribute for HTMLAnchorElement, in §11.3.5
- Shift_JIS, in §8.2.2.3
- shipping, in §4.10.19.8.1
- should be used, in §4.7.8
- show, in §Unnumbered section
-
showing
- mode for track, in §4.7.14.11.1
- enum-value for TextTrackMode, in §4.7.14.11.5
- enum for TextTrackMode, in §4.7.14.11.5
- "showing", in §4.7.14.11.5
- showModalDialog(), in §7.5.3
- showModalDialog(url), in §7.5.3
- showModalDialog(url, argument), in §7.5.3
- shown, in §2.1
- show poster flag, in §4.7.14.6
- shows caching progress, in §11.3.4.2
- sign, in §4.7.14.10.1
- signal a type change, in §4.10.5
- simple color, in §2.4.6
-
size
- definition of, in §2.6.2
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.3.2
- element-attr for select, in §4.10.7
- attribute for HTMLSelectElement, in §4.10.7
- element-attr for hr, in §11.2
- attribute for HTMLFontElement, in §11.3.5
- attribute for HTMLHRElement, in §11.3.5
-
sizes
- attribute for HTMLLinkElement, in §4.2.4
- element-attr for source, in §4.7.4
- element-attr for img, in §4.7.5
- attribute for HTMLImageElement, in §4.7.5
- element-attr for link, in §4.8.6.5
- skip whitespace, in §2.4.1
-
slide
- attr-value for marquee/behavior, in §11.3.2
- state for marquee/behavior, in §11.3.2
- slots, in §4.9.12
- small, in §4.5.4
- sms:, in §2.2.2
- Soft, in §4.10.11
- soft, in §4.10.11
- solitary callback microtasks, in §7.1.4.2
- source, in §4.7.12
- source browsing context, in §6.7.1
- source node, in §5.7.5
- source set, in §4.7.5
- source size, in §4.7.5
- Source text, in §7.1.3.1
- space characters, in §2.4.1
- spacer, in §11.2
-
span
- (element), in §4.5.28
- element-attr for colgroup, in §4.9.3
- attribute for HTMLTableColElement, in §4.9.3
- element-attr for col, in §4.9.4
- span multiple columns, in §4.9.11
- Special, in §8.2.3.2
- specified, in §5.7.8
- specifies an operation, in §5.7.8
- specify an operation, in §5.7.8
- spellcheck, in §5.6.5
- spinning the event loop, in §7.1.4.2
- spins the event loop, in §7.1.4.2
- spin the event loop, in §7.1.4.2
- split a string on commas, in §2.4.8
- split a string on spaces, in §2.4.7
- spoon-feed the parser, in §9.2
-
src
- element-attr for img, in §4.7.5
- attribute for HTMLImageElement, in §4.7.5
- element-attr for iframe, in §4.7.6
- attribute for HTMLIFrameElement, in §4.7.6
- element-attr for embed, in §4.7.7
- attribute for HTMLEmbedElement, in §4.7.7
- element-attr for source, in §4.7.12
- attribute for source, in §4.7.12
- element-attr for track, in §4.7.13
- attribute for HTMLTrackElement, in §4.7.13
- element-attr for media, in §4.7.14.2
- attribute for HTMLMediaElement, in §4.7.14.2
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.1.19
- element-attr for script, in §4.12.1
- attribute for HTMLScriptElement, in §4.12.1
- element-attr for frame, in §11.3.3
- attribute for HTMLFrameElement, in §11.3.3
-
srcdoc
- element-attr for iframe, in §4.7.6
- attribute for HTMLIFrameElement, in §4.7.6
-
srclang
- element-attr for track, in §4.7.13
- attribute for HTMLTrackElement, in §4.7.13
- srcObject, in §4.7.14.2
-
srcset
- element-attr for source, in §4.7.4
- element-attr for img, in §4.7.5
- attribute for HTMLImageElement, in §4.7.5
- stack of open elements, in §8.2.3.2
- stack of template insertion modes, in §8.2.3.1
- stalled, in §4.7.14.15
- stall timeout, in §4.7.14.5
-
standby
- element-attr for object, in §11.2
- attribute for HTMLObjectElement, in §11.3.5
- start(), in §11.3.2
-
start
- element-attr for ol, in §4.4.5
- attribute for HTMLOListElement, in §4.4.5
- enum-value for SelectionMode, in §4.10.20
- enum for SelectionMode, in §4.10.20
- event for marquee, in §11.3.2
- "start", in §4.10.20
- start(index), in §4.7.14.13
- start tag, in §8.1.2.1
- start tags, in §8.1.2.1
- start the track processing model, in §4.7.14.11.3
- start the WebSocket closing handshake, in §2.2.2
- startTime, in §4.7.14.11.5
-
state
- dfn for image, in §4.7.5
- attribute for History, in §6.6.2
- attribute for PopStateEvent, in §6.7.10.2
- state object, in §6.6.1
- state of the type attribute, in §4.10.5.1
- states of the type attribute, in §4.10.5.1
- statically validate the constraints, in §4.10.21.2
- statically validating the constraints, in §4.10.21.2
-
status
- attribute for Window, in §6.3.6
- attribute for ApplicationCache, in §11.3.4.8
- statusbar, in §6.3.6
-
step
- attribute for HTMLInputElement, in §4.10.5
- element-attr for input, in §4.10.5.3.8
- step-align, in §4.10.5.4
- step-aligned, in §4.10.5.4
- step-aligns, in §4.10.5.4
- step base, in §4.10.5.3.8
- stepDown(n), in §4.10.5.4
- stepMismatch, in §4.10.21.3
- step scale factor, in §4.10.5.3.8
- steps to expose a media-resource-specific text track, in §4.7.14.11.2
- stepUp(n), in §4.10.5.4
-
stop()
- method for Window, in §6.3.1
- method for HTMLMarqueeElement, in §11.3.2
- stopped, in §8.2.6
- stopped due to errors, in §4.7.14.8
- stopped parsing, in §8.2.6
- stops parsing, in §8.2.6
- storage, in §Unnumbered section
- strictly split, in §2.4.1
- strictly split a string, in §2.4.1
- strictly splitting the string, in §2.4.1
- strike, in §11.2
-
stringification behavior
- dfn for HTMLHyperlinkElementUtils, in §4.8.3
- dfn for Location, in §6.6.4
- strip and collapse whitespace, in §2.4.1
- strip leading and trailing whitespace, in §2.4.1
- strip line breaks, in §2.4.1
- stripped line breaks, in §2.4.1
- stripping and collapsing whitespace, in §2.4.1
- stripping leading and trailing whitespace, in §2.4.1
- strong, in §4.5.3
- StructuredClone, in §2.9.4
- StructuredCloneWithTransfer, in §2.9.3
-
style
- element-attr for global, in §3.2.5.8
- (element), in §4.2.6
- style data, in §4.2.6
- stylesheet, in §4.8.6.10
- style sheet ready, in §4.2.7
- sub, in §4.5.21
- submenu label, in §4.11.3
- submit(), in §4.10.3
-
submit
- attr-value for input/type, in §4.10.5
- attr-value for button/type, in §4.10.6
- definition of, in §4.10.22.3
- event for global, in §Unnumbered section
- Submit as entity body, in §4.10.22.3
-
submit button
- definition of, in §4.10.2
- element-state for button/type, in §4.10.6
- Submit Button, in §4.10.5.1.18
- submit buttons, in §4.10.2
- submittable, in §4.10.2
- Submittable element, in §4.10.2
- Submittable elements, in §4.10.2
- submitted, in §4.10.22.3
- subprotocol in use, in §2.2.2
- substantial, in §10.3.10
- Subtitles, in §4.7.13
-
subtitles
- attr-value for track/kind, in §4.7.13
- attr-value for commonTrack/kind, in §4.7.14.10.1
- definition of, in §4.7.14.11.1
- enum-value for TextTrackKind, in §4.7.14.11.5
- "subtitles", in §4.7.14.11.5
- suffer from a custom error, in §4.10.21.1
- suffer from an overflow, in §4.10.21.1
- suffer from an underflow, in §4.10.21.1
- suffer from a pattern mismatch, in §4.10.21.1
- suffer from a step mismatch, in §4.10.21.1
- suffer from a type mismatch, in §4.10.21.1
- suffer from bad input, in §4.10.21.1
- suffer from being missing, in §4.10.21.1
- suffer from being too long, in §4.10.21.1
- suffer from being too short, in §4.10.21.1
- suffering from a custom error, in §4.10.21.1
- suffering from an overflow, in §4.10.21.1
- suffering from an underflow, in §4.10.21.1
- suffering from a pattern mismatch, in §4.10.21.1
- suffering from a step mismatch, in §4.10.21.1
- suffering from a type mismatch, in §4.10.21.1
- suffering from bad input, in §4.10.21.1
- suffering from being missing, in §4.10.21.1
- suffering from being too long, in §4.10.21.1
- suffering from being too short, in §4.10.21.1
- suffixes, in §7.6.1.5
- suggestions source element, in §4.10.5.3.9
- suitable sequentially focusable area, in §5.4.5
-
summary
- (element), in §4.11.2
- element-attr for table, in §11.2
- attribute for HTMLTableElement, in §11.3.5
- sup, in §4.5.21
- supported, in §2.1.1
- supported token, in §2.2.2
- supported tokens, in §2.2.2
- supporting the suggested default rendering, in §2.2.1
- support the suggested default rendering, in §2.2.1
- suspend, in §4.7.14.15
- svg, in §4.7.19
- SVG namespace, in §2.8
- swapCache(), in §11.3.4.8
- synchronous section, in §7.1.4.2
- synchronous sections, in §7.1.4.2
- syntax for which, in §8.1.2.3
- tabindex, in §5.4.3
- tabIndex, in §5.4.3
- tabindex focus flag, in §5.4.3
-
table
- (element), in §4.9.1
- definition of, in §4.9.12
- table design techniques, in §4.9.1.1
- table model, in §4.9.12
- table model error, in §4.9.12
- tables, in §4.9.12
- tag, in §4.8.6.11
- Tag clouds, in §4.13.3
- tag name, in §8.1.2
- Tag omission in text/html, in §3.2.3
- Tags, in §8.1.2
- taintEnabled(), in §7.6.1.1
- :target, in §6.7.9
-
target
- element-attr for base, in §4.2.3
- attribute for HTMLBaseElement, in §4.2.3
- attribute for HTMLAnchorElement, in §4.5.1
- attribute for HTMLAreaElement, in §4.7.16
- element-attr for a, area, links, in §4.8.2
- element-attr for form, in §4.10.19.6
- attribute for HTMLFormElement, in §4.10.19.6
- element-attr for link, in §11.2
- attribute for HTMLLinkElement, in §11.3.5
- target element, in §6.7.9
- target override, in §2.2.2
- task queues, in §7.1.4.1
- tasks, in §7.1.4.1
- task source, in §7.1.4.1
- tBodies, in §4.9.1
- tbody, in §4.9.5
- td, in §4.9.9
-
tel
- attr-value for input/type, in §4.10.5
- value for form/inputmode, in §4.10.19.7
-
Telephone
- element-state for input, in §4.10.5.1.3
- state for inputmode, in §4.10.19.7
- template, in §4.12.3
- template contents, in §4.12.3
- temporary buffer, in §8.2.4
- term, in §4.5.8
- termination nesting level, in §6.7.11
-
Text
- definition of, in §3.2.4.2.5
- element-state for input, in §4.10.5.1.2
-
text
- attribute for HTMLTitleElement, in §4.2.2
- attribute for HTMLAnchorElement, in §4.5.1
- attr-value for input/type, in §4.10.5
- attribute for HTMLOptionElement, in §4.10.10
- attribute for HTMLScriptElement, in §4.12.1
- element-attr for body, in §11.2
- attribute for HTMLBodyElement, in §11.3.5
- textarea, in §4.10.11
- textarea effective height, in §10.5.15
- textarea effective width, in §10.5.15
- textarea wrapping transformation, in §4.10.11
- Text content, in §3.2.4.2.5
- textLength, in §4.10.11
- text/plain, in §4.10.19.6
- text/plain encoding algorithm, in §4.10.22.8
- TextTrack, in §4.7.14.11.5
- text track cue, in §4.7.14.11.1
- TextTrackCue, in §4.7.14.11.5
- text track cue active flag, in §4.7.14.11.1
- text track cue data, in §4.7.14.11.1
- text track cue display state, in §4.7.14.11.1
- text track cue end time, in §4.7.14.11.1
- text track cue identifier, in §4.7.14.11.1
- TextTrackCueList, in §4.7.14.11.5
- text track cue order, in §4.7.14.11.1
- text track cue pause-on-exit flag, in §4.7.14.11.1
- text track cue start time, in §4.7.14.11.1
- text track cue writing direction, in §2.2.2
- text track failed to load, in §4.7.14.11.1
- text track in-band metadata track dispatch type, in §4.7.14.11.1
- text track kind, in §4.7.14.11.1
- text track kinds, in §4.7.14.11.1
- text track label, in §4.7.14.11.1
- text track language, in §4.7.14.11.1
- TextTrackList, in §4.7.14.11.5
- text track list of cues, in §4.7.14.11.1
- text track loaded, in §4.7.14.11.1
- text track loading, in §4.7.14.11.1
- text track mode, in §4.7.14.11.1
- text track not loaded, in §4.7.14.11.1
- text track readiness state, in §4.7.14.11.1
- text track rules for extracting the chapter title, in §4.7.14.11.1
- textTracks, in §4.7.14.11.5
- text tracks, in §4.7.14.11.1
- tFoot, in §4.9.1
- tfoot, in §4.9.7
- th, in §4.9.10
- that algorithm, in §8.4
- thead, in §4.9.6
- tHead, in §4.9.1
- the address, in §3.1
- the conditions described above, in §4.7.5.1.16
- the directionality, in §3.2.5.6
- the document address, in §3.1
- the Document object is indexed for property retrieval, in §3.1.3
- the document’s address, in §3.1
- The document’s referrer, in §3.1
- The drag data item kind, in §5.7.2
- The drag data item type string, in §5.7.2
- the element’s directionality, in §3.2.5.6
- The embed element setup steps, in §4.7.7
- the empty string, in §4.7.14.3
- the environment settings object’s global object, in §7.1.3.5
- the environment settings object’s Realm, in §7.1.3.5
- The event handler processing algorithm, in §7.1.5.1
- the first 1024 bytes, in §4.2.5.5
- the global object’s Realm, in §7.1.3.5
- the handling for misnested tags, in §8.2.5.4.7
- The HTML syntax, in §8
- the indicated part of the document, in §6.7.9
- the kind of text track, in §4.7.14.11.1
- the link is an alternative stylesheet, in §4.8.6.10
- The location bar BarProp object, in §6.3.6
- the manifest, in §11.3.4
- The menu bar BarProp object, in §6.3.6
- the outline’s owner, in §4.3.10.1
- The personal bar BarProp object, in §6.3.6
- the Realm’s global object, in §7.1.3.5
- the Realm’s settings object, in §7.1.3.5
- the resource’s content-type metadata, in §2.6.4
- the rules described previously, in §4.7.14.5
- The rules for choosing a browsing context given a browsing context name, in §6.1.5
- the script is ready, in §4.12.1.1
- the script’s script, in §4.12.1.1
- the script’s type, in §4.12.1.1
- The scrollbar BarProp object, in §6.3.6
- The status bar BarProp object, in §6.3.6
- the step labeled fragment identifiers, in §6.7.1
- the text insertion mode, in §8.2.5.4.8
- the text tracks are ready, in §4.7.14.11.1
- The toolbar BarProp object, in §6.3.6
- the WebSocket closing handshake is started, in §2.2.2
- the WebSocket connection close code, in §2.2.2
- the WebSocket connection close reason, in §2.2.2
- the WebSocket connection is closed, in §2.2.2
- the WebSocket connection is established, in §2.2.2
- the Window object is indexed for property retrieval, in §6.3.3
- The XHTML syntax, in §9
- third administrative level, in §4.10.19.8.1
-
this
- dfn for conventions, in §1.7.2
- element for conventions, in §1.7.2
- through which new document is nested, in §6.1.1
- throw, in §2.2.2
-
time
- definition of, in §2.4.5.4
- (element), in §4.5.16
- attr-value for input/type, in §4.10.5
- Time, in §4.10.5.1.10
- timeline offset, in §4.7.14.6
- time marches on, in §4.7.14.8
- TimeRanges, in §4.7.14.13
- timer initialization steps, in §7.4
- timer nesting level, in §7.4
- timer task source, in §7.4
- timeupdate, in §4.7.14.15
- time zone, in §2.4.5.6
- time-zone offset, in §2.4.5.6
-
title
- attribute for Document, in §3.1.3
- element-attr for global, figure, div, img, textarea, meter, in §3.2.5.2
- (element), in §4.2.2
- element-attr for link, in §4.2.4
- element-attr for style, in §4.2.6
- element-attr for dfn, in §4.5.8
- element-attr for abbr, in §4.5.9
- element-attr for input, in §4.10.5.3.6
- element-attr for menuitem, in §4.11.4
- toBlob(), in §4.12.4
- toBlob(_callback), in §4.12.4
- toBlob(_callback, type), in §4.12.4
- toBlob(_callback, type, arguments...), in §4.12.4
- toDataURL(), in §4.12.4
-
toggle
- definition of, in §4.10.7
- event for global, in §Unnumbered section
- tokenization, in §8.2.4
- tokenizer, in §8.2.4
- toolbar, in §6.3.6
- tooLong, in §4.10.21.3
- tooShort, in §4.10.21.3
-
top
- definition of, in §6.1.1.1
- attribute for Window, in §6.3
- top-level browsing context, in §6.1.1
- @@toPrimitive, in §2.2.2
- @@toStringTag, in §2.2.2
- tr, in §4.9.8
-
track
- (element), in §4.7.13
- attribute for HTMLTrackElement, in §4.7.13
- attribute for TextTrackCue, in §4.7.14.11.5
- attribute for TrackEvent, in §4.7.14.14
- TrackEvent, in §4.7.14.14
- TrackEvent(type), in §4.7.14.14
- TrackEvent(type, eventInitDict), in §4.7.14.14
- track label, in §4.7.13
- track language, in §4.7.13
- track URL, in §4.7.13
- Transfer, in §2.9.2
- Transferable objects, in §2.9.2
- TransferHelper, in §2.9.6
- transformToDocument(), in §2.2.2
- transformToFragment(), in §2.2.2
- translatable attributes, in §3.2.5.4
- translate, in §3.2.5.4
- translate-enabled, in §3.2.5.4
- translation, in §4.7.14.10.1
- translation mode, in §3.2.5.4
- transparent, in §3.2.4.3
- transparently follow the redirect, in §2.6.2
- traverse the history, in §6.7.10
- traverse the history by a delta, in §6.6.2
- traversing the history, in §6.7.10
- tree construction dispatcher, in §8.2.5
- tree order, in §2.1.3
- true-by-default, in §5.6.5
- truespeed, in §11.3.2
- trueSpeed, in §11.3.2
- trusted, in §2.1.4
- trusted event, in §2.1.4
- tt, in §11.2
- tuple, in §6.4
- tuple origin, in §6.4
- turned off, in §11.3.2
- turned on, in §11.3.2
-
type
- element-attr for link, in §4.2.4
- attribute for HTMLLinkElement, in §4.2.4
- element-attr for style, in §4.2.6
- attribute for HTMLStyleElement, in §4.2.6
- element-attr for ol, in §4.4.5
- attribute for HTMLOListElement, in §4.4.5
- attribute for HTMLAnchorElement, in §4.5.1
- element-attr for embed, in §4.7.7
- element-attr for object, in §4.7.8
- element-attr for source, in §4.7.12
- attribute for source, in §4.7.12
- attribute for HTMLAreaElement, in §4.7.16
- element-attr for a, links, in §4.8.2
- element-attr for input, in §4.10.5
- attribute for HTMLInputElement, in §4.10.5
- element-attr for button, in §4.10.6
- attribute for HTMLButtonElement, in §4.10.6
- attribute for HTMLSelectElement, in §4.10.7
- attribute for HTMLTextAreaElement, in §4.10.11
- attribute for HTMLKeygenElement, in §4.10.12
- attribute for HTMLOutputElement, in §4.10.13
- attribute for HTMLFieldSetElement, in §4.10.16
- element-attr for menu, in §4.11.3
- attribute for HTMLMenuElement, in §4.11.3
- element-attr for menuitem, in §4.11.4
- attribute for HTMLMenuItemElement, in §4.11.4
- element-attr for script, in §4.12.1
- attribute for HTMLScriptElement, in §4.12.1
- attribute for DataTransferItem, in §5.7.3.2
- attribute for MimeType, in §7.6.1.5
- element-attr for area, in §11.2
- element-attr for param, in §11.2
- element-attr for li, in §11.2
- element-attr for ul, in §11.2
- attribute for HTMLLIElement, in §11.3.5
- attribute for HTMLParamElement, in §11.3.5
- type information, in §2.6.4
- typeMismatch, in §4.10.21.3
- typeMustMatch, in §4.7.8
- type of the content, in §4.7.7
- types, in §5.7.3
- type string, in §5.7.2
- u, in §4.5.24
- ul, in §4.4.6
- Unavailable, in §4.7.5
- unavailable, in §4.7.5
- UNCACHED, in §11.3.4.8
- unfocusing steps, in §5.4.4
- Unhandled promise rejections, in §7.1.3.9
- Unicode character, in §2.1.6
- Unicode code point, in §2.1.6
- unicode serialization, in §6.4
- unicode serialization of an origin, in §6.4
- uninitialized, in §5.7.3
- unit of related browsing contexts, in §6.1.4
- unit of related similar-origin browsing contexts, in §6.1.4
- units of related similar-origin browsing contexts, in §6.1.4
-
unload
- definition of, in §6.7.11
- event for global, in §Unnumbered section
- unload a document, in §6.7.11
- unloaded, in §6.7.11
- unloading document cleanup steps, in §6.7.11
- unloading document visibility change steps, in §6.7.11
- unordered set of unique space-separated tokens, in §2.4.7
- unquoted, in §8.1.2.3
- unregisterProtocolHandler(scheme, url), in §7.6.1.3
- unstyled document, in §10.9
-
up
- attr-value for marquee/direction, in §10.5.11
- state for marquee, in §11.3.2
- update(), in §11.3.4.8
- update a style block, in §4.2.6
- update href, in §4.8.3
- UPDATEREADY, in §11.3.4.8
- update status, in §11.3.4
- update the image data, in §4.7.5
- update the session history with the new page, in §6.7.1
- update the source set, in §4.7.5
- updating the session history with the new page, in §6.7.1
- upgrade attempt, in §11.3.4.2
- upgrade the pending request to the current request, in §4.7.5
- upper-alpha, in §4.4.5
- uppercase ASCII hex digits, in §2.4.1
- uppercase ASCII letters, in §2.4.1
- upper-roman, in §4.4.5
-
URL
- element-state for input, in §4.10.5.1.4
- state for inputmode, in §4.10.19.7
-
url
- attr-value for input/type, in §4.10.5
- value for form/inputmode, in §4.10.19.7
- dfn for Location, in §6.6.4
-
urn
- element-attr for a, in §11.2
- element-attr for link, in §11.2
- urn:, in §2.2.2
- Use Credentials, in §2.6.6
- use-credentials, in §2.6.6
- used during the parsing, in §8.2.5.4.4
-
usemap
- element-attr for img, in §4.7.5
- element-attr for common, in §4.7.17
- element-attr for input, in §11.2
- element-attr for object, in §11.2
-
useMap
- attribute for HTMLImageElement, in §4.7.5
- attribute for HTMLInputElement, in §11.3.5
- attribute for HTMLObjectElement, in §11.3.5
- userAgent, in §7.6.1.1
- User agents with no scripting support, in §2.2.1
- user interaction task source, in §7.1.4.3
- username, in §4.8.3
- use srcset or picture, in §4.7.5
- using the rules for, in §8.2.3.1
- UTF-16BE, in §8.2.2.3
- UTF-16 encoding, in §2.1.6
- UTF-16LE, in §8.2.2.3
- UTF-8, in §8.2.2.3
- UTF-8 decode, in §2.2.2
- UTF-8 decode without BOM, in §2.2.2
- UTF-8 decode without BOM or fail, in §2.2.2
- UTF-8 encode, in §2.2.2
- valid, in §4.10.21.3
- :valid, in §4.15.2
- validate the server’s response, in §2.2.2
- validationMessage, in §4.10.21.3
- valid browsing context name, in §6.1.5
- valid browsing context name or keyword, in §6.1.5
- valid browsing context names or keywords, in §6.1.5
- valid date string, in §2.4.5.2
- valid date string with optional time, in §2.4.5.10
- valid duration string, in §2.4.5.9
- valid e-mail address, in §4.10.5.1.5
- valid e-mail address list, in §4.10.5.1.5
- valid floating date and time string, in §2.4.5.5
- valid floating-point number, in §2.4.4.3
- valid global date and time string, in §2.4.5.7
- valid hash-name reference, in §2.4.9
- valid integer, in §2.4.4.1
- valid integers, in §2.4.4.1
- validity, in §4.10.21.3
- ValidityState, in §4.10.21.3
- validity states, in §4.10.21.1
- valid list of floating-point numbers, in §2.4.4.6
- valid lowercase simple color, in §2.4.6
- valid media query list, in §2.4.10
- valid MIME type, in §2.1.1
- valid MIME types with no parameters, in §2.1.1
- valid MIME type with no parameters, in §2.1.1
- valid month string, in §2.4.5.1
- valid non-empty URL, in §2.5.1
- valid non-empty URL potentially surrounded by spaces, in §2.5.1
- valid non-negative integer, in §2.4.4.2
- valid normalized floating date and time string, in §2.4.5.5
- valid normalized global date and time string, in §2.4.5.7
- valid simple color, in §2.4.6
- valid source size list, in §4.7.5
- valid time string, in §2.4.5.4
- valid time-zone offset string, in §2.4.5.6
- valid URL, in §2.5.1
- valid URL potentially surrounded by spaces, in §2.5.1
- valid week string, in §2.4.5.8
- valid yearless date string, in §2.4.5.3
-
vAlign
- attribute for HTMLTableColElement, in §11.3.5
- attribute for HTMLTableSectionElement, in §11.3.5
- attribute for HTMLTableCellElement, in §11.3.5
- attribute for HTMLTableRowElement, in §11.3.5
-
valign
- element-attr for col, in §11.2
- element-attr for tbody, thead, tfoot, tablesection, in §11.2
- element-attr for td, th, tablecells, in §11.2
- element-attr for tr, in §11.2
-
value
- element-attr for li, in §4.4.7
- attribute for HTMLLIElement, in §4.4.7
- element-attr for data, in §4.5.15
- attribute for HTMLDataElement, in §4.5.15
- element-attr for param, in §4.7.9
- attribute for HTMLParamElement, in §4.7.9
- element-attr for input, in §4.10.5
- attribute for HTMLInputElement, in §4.10.5.4
- mode for input, in §4.10.5.4
- element-attr for button, in §4.10.6
- attribute for HTMLButtonElement, in §4.10.6
- attribute for HTMLSelectElement, in §4.10.7
- element-attr for option, in §4.10.10
- attribute for HTMLOptionElement, in §4.10.10
- attribute for HTMLTextAreaElement, in §4.10.11
- mode for output, in §4.10.13
- attribute for HTMLOutputElement, in §4.10.13
- element-attr for progress, in §4.10.14
- attribute for HTMLProgressElement, in §4.10.14
- element-attr for meter, in §4.10.15
- attribute for HTMLMeterElement, in §4.10.15
- dfn for forms, in §4.10.18.1
- valueAsDate, in §4.10.5.4
- valueAsNumber, in §4.10.5.4
- valueMissing, in §4.10.21.3
- value mode flag, in §4.10.13
- values, in §4.10.18.1
- value sanitization algorithm, in §4.10.5
- values are reset, in §6.7.10
- valuetype, in §11.2
- valueType, in §11.3.5
- var, in §4.5.18
- verbatim, in §4.10.19.7
-
version
- element-attr for html, in §11.2
- attribute for HTMLHtmlElement, in §11.3.5
- video, in §4.7.10
- videoHeight, in §4.7.10
- VideoTrack, in §4.7.14.10.1
- VideoTrack.id, in §4.7.14.10.1
- VideoTrack.kind, in §4.7.14.10.1
- VideoTrack.label, in §4.7.14.10.1
- VideoTrack.language, in §4.7.14.10.1
- VideoTrackList, in §4.7.14.10.1
- VideoTrackList.getTrackById(id), in §4.7.14.10.1
- VideoTrackList.length, in §4.7.14.10.1
- VideoTrackList.selectedIndex, in §4.7.14.10.1
- videoTracks, in §4.7.14.10
- VideoTrack.selected, in §4.7.14.10.1
- videoWidth, in §4.7.10
- viewport, in §2.2.2
- viewport-based selection, in §4.7.1
-
visible
- definition of, in §2.1
- attribute for BarProp, in §6.3.6
- :visited, in §4.15.2
- Visual user agents that support the suggested default rendering, in §2.2.1
- vlink, in §11.2
- vLink, in §11.3.5
- vlinkColor, in §11.3.5
- Void elements, in §8.1.2
- volume, in §4.7.14.12
- volumechange, in §4.7.14.15
-
vspace
- element-attr for embed, in §11.2
- element-attr for iframe, in §11.2
- element-attr for input, in §11.2
- element-attr for img, in §11.2
- element-attr for object, in §11.2
- attribute for HTMLAppletElement, in §11.3.1
- attribute for HTMLMarqueeElement, in §11.3.2
- attribute for HTMLImageElement, in §11.3.5
- attribute for HTMLObjectElement, in §11.3.5
- waiting, in §4.7.14.15
- wbr, in §4.5.30
-
webgl
- context for canvas, in §4.12.4
- definition of, in §4.12.4
- WebVTT, in §2.2.2
- WebVTT file, in §2.2.2
- WebVTT file using chapter title text, in §2.2.2
- WebVTT file using cue text, in §2.2.2
- WebVTT file using only nested cues, in §2.2.2
- WebVTT parser, in §2.2.2
-
week
- definition of, in §2.4.5.8
- attr-value for input/type, in §4.10.5
- Week, in §4.10.5.1.9
- week number of the last day, in §2.4.5.8
- white_space, in §2.4.1
- white_space characters, in §2.4.1
-
width
- attribute for HTMLImageElement, in §4.7.5
- attribute for HTMLIFrameElement, in §4.7.6
- attribute for HTMLEmbedElement, in §4.7.7
- attribute for HTMLObjectElement, in §4.7.8
- element-attr for media, img, iframe, embed, object, video, input, in §4.7.20
- attribute for media, in §4.7.20
- attribute for HTMLInputElement, in §4.10.5
- element-attr for canvas, in §4.12.4
- attribute for HTMLCanvasElement, in §4.12.4
- attribute for ImageBitmap, in §7.7
- element-attr for col, in §11.2
- element-attr for hr, in §11.2
- element-attr for pre, in §11.2
- element-attr for table, in §11.2
- element-attr for td, th, tablecells, in §11.2
- attribute for HTMLAppletElement, in §11.3.1
- attribute for HTMLMarqueeElement, in §11.3.2
- attribute for HTMLTableColElement, in §11.3.5
- attribute for HTMLHRElement, in §11.3.5
- attribute for HTMLPreElement, in §11.3.5
- attribute for HTMLTableElement, in §11.3.5
- attribute for HTMLTableCellElement, in §11.3.5
- width descriptor, in §4.7.5
- width descriptor value, in §4.7.5
- width of the select’s labels, in §10.5.14
- willful violation, in §1.5.2
- willValidate, in §4.10.21.3
- window, in §6.3
- Window, in §6.3
- WindowBase64, in §7.2
- WindowEventHandlers, in §7.1.5.2.1
- WindowModal, in §7.5.3
- WindowProxy, in §6.3.7
- windowproxy defineownproperty, in §6.3.7.1.6
- windowproxy delete, in §6.3.7.1.9
- windowproxy get, in §6.3.7.1.7
- windowproxy getownproperty, in §6.3.7.1.5
- windowproxy getprototypeof, in §6.3.7.1.1
- windowproxy isextensible, in §6.3.7.1.3
- windowproxy ownpropertykeys, in §6.3.7.1.10
- windowproxy preventextensions, in §6.3.7.1.4
- windowproxy set, in §6.3.7.1.8
- windowproxy setprototypeof, in §6.3.7.1.2
- windows-1250, in §8.2.2.3
- windows-1251, in §8.2.2.3
- windows-1252, in §8.2.2.3
- windows-1254, in §8.2.2.3
- windows-1256, in §8.2.2.3
- windows-1257, in §8.2.2.3
- window slot, in §6.3.7
- WindowTimers, in §7.4
-
wrap
- element-attr for textarea, in §4.10.11
- attribute for HTMLTextAreaElement, in §4.10.11
- wrap callbacks, in §7.1.4.2
- write(), in §7.3.3
- writeln(), in §7.3.4
- XHTML document, in §2.1
- XHTML documents, in §2.1
- XLink namespace, in §2.8
- xml:base, in §3.2.5.5
- XML-compatible, in §2.1.2
- XML document, in §2.1
- XML fragment parsing algorithm, in §9.4
- XML fragment serialization algorithm, in §9.3
- XML MIME type, in §2.1.2
- XML namespace, in §2.8
- XMLNS namespace, in §2.8
- XML parser, in §9.2
- XML scripting support disabled, in §9.2
- XML scripting support enabled, in §9.2
- xmp, in §11.2
- XSLTProcessor, in §2.2.2
- x-user-defined, in §8.2.2.3
- yearless date, in §2.4.5.3
- yet more restrictions, in §8.1.2.5
Terms defined by reference
-
[CSP3] defines the following terms:
- content security policy
- content security policy directive
- content security policy syntax
- directives
- enforce the policy
- enforced
- ensurecspdoesnotblockstringcompilation
- frame-ancestors
- frame-ancestors directive
- initialize a document's csp list
- initialize a global object's csp list
- is base allowed for document?
- parse a serialized content security policy
- report-uri
- sandbox
- sandbox directive
- should element's inline behavior be blocked by content security policy?
- valid content security policy
- [CSSOM] defines the following terms:
- [CSSOM-VIEW] defines the following terms:
- [DOM] defines the following terms:
- [DOM-Parsing] defines the following terms:
-
[ECMA-262] defines the following terms:
- %arraybuffer%
- %arrayprototype%
- %objproto_tostring%
- %objproto_valueof%
- ArrayBuffer
- Date
- Error
- Function
- RangeError
- RegExp
- SyntaxError
- TypeError
- abstract equality comparison
- arraycreate
- automatic semicolon insertion
- call
- clonearraybuffer
- construct
- createdataproperty
- current realm
- current realm record
- detacharraybuffer
- directive prologue
- early error
- enqueuejob
- functionbody
- functioncreate
- get
- getactivescriptormodule
- getfunctionrealm
- hasownproperty
- hostensurecancompilestrings
- hostpromiserejectiontracker
- initializehostdefinedrealm
- isaccessordescriptor
- iscallable
- isconstructor
- isdatadescriptor
- isdetachedbuffer
- javascript execution context
- javascript execution context stack
- javascript realm
- list
- newobjectenvironment
- ordinarydefineownproperty
- ordinarydelete
- ordinaryget
- ordinarygetownproperty
- ordinarygetprototypeof
- ordinaryisextensible
- ordinaryownpropertykeys
- ordinarypreventextensions
- ordinaryset
- ordinarysetprototypeof
- parsescript
- pattern
- property descriptor
- propertydescriptor
- realm
- record
- runjobs
- running javascript execution context
- samevalue
- script
- scriptevaluation
- strict equality comparison
- the typedarray constructors
- toboolean
- tostring
- touint32
- type
- typedarraycreate
- typeof
- use strict directive
- well-known intrinsic objects
- well-known symbols
- [ENCODING] defines the following terms:
-
[FETCH] defines the following terms:
- body
- cache mode
- client
- cors protocol
- cors-cross-origin
- credentials mode
- cryptographic nonce metadata
- csp list
- default user-agent value
- destination
- extract a mime type
- fetch
- fetching algorithm
- header list
- https state
- https state value
- initiator
- internal response
- method
- mode
- ok status
- omit-origin-header flag
- origin
- origin header
- parser metadata
- process response
- redirect mode
- referrer
- referrer policy
- request
- requestcredentials
- response
- same-origin data-url flag
- set
- status
- synchronous flag
- target browsing context
- terminate
- type
- unsafe-request flag
- url
- url list
- use-url-credentials flag
- [RESOURCE-HINTS] defines the following terms:
- [SELECTION-API] defines the following terms:
- [UIEVENTS] defines the following terms:
-
[URL] defines the following terms:
- application/x-www-form-urlencoded serializer
- basic url parser
- default encode set
- domain
- domain to ascii
- domain to unicode
- fragment
- fragment state
- host
- host equals
- host parser
- host serializer
- host state
- hostname state
- ipv4
- ipv6
- network scheme
- origin
- parse errors
- parsed urls
- path
- path start state
- percent decode
- percent encode
- port
- port state
- query
- query state
- relative schemes
- scheme
- scheme start state
- serialization
- serialize an integer
- serialized
- set the password
- set the username
- url
- url parser
- url serializer
- username
- utf-8 percent encode
- [WHATWG] defines the following terms:
- [WEBWORKERS] defines the following terms:
- [XML] defines the following terms:
-
[aria] defines the following terms:
- alert
- alertdialog
- application
- article
- banner
- button
- checkbox
- columnheader
- combobox
- complementary
- contentinfo
- dialog
- directory
- document
- grid
- gridcell
- group
- heading
- img
- link
- list
- listbox
- listitem
- log
- main
- marquee
- menu
- menubar
- menuitem
- menuitemcheckbox
- menuitemradio
- navigation
- note
- option
- presentation
- progressbar
- radio
- radiogroup
- region
- row
- rowgroup
- rowheader
- search
- separator
- slider
- spinbutton
- status
- tab
- tablist
- tabpanel
- textbox
- toolbar
- tree
- treeitem
- [aria-1.1] defines the following terms:
- [css-cascade-3] defines the following terms:
- [css-color-4] defines the following terms:
- [CSS3-CONTENT] defines the following terms:
- [css-display-3] defines the following terms:
- [CSS-FONT-LOADING-3] defines the following terms:
- [CSS-FONTS-3] defines the following terms:
- [css-images-4] defines the following terms:
- [css-lists-3] defines the following terms:
- [css-overflow-3] defines the following terms:
- [CSS3-RUBY] defines the following terms:
- [css-sizing-3] defines the following terms:
- [CSS-STYLE-ATTR] defines the following terms:
- [CSS-SYNTAX-3] defines the following terms:
- [css-text-3] defines the following terms:
- [css-transitions-1] defines the following terms:
- [css-ui-4] defines the following terms:
- [CSS-VALUES] defines the following terms:
- [CSS-WRITING-MODES-3] defines the following terms:
- [CSS2] defines the following terms:
-
[CSS22] defines the following terms:
- background-color
- background-image
- border-bottom-color
- border-bottom-style
- border-bottom-width
- border-left-color
- border-left-style
- border-left-width
- border-right-color
- border-right-style
- border-right-width
- border-top-color
- border-top-style
- border-top-width
- cursor
- display
- letter-spacing
- margin-bottom
- margin-left
- margin-right
- margin-top
- outline
- padding-bottom
- padding-left
- padding-right
- padding-top
- solid
- vertical-align
- white-space
- [CSS-SYNTAX-3] defines the following terms:
- [CSSOM] defines the following terms:
- [CSSOM-VIEW] defines the following terms:
-
[DOM] defines the following terms:
- Attr
- ChildNode
- Comment
- DOMImplementation
- DOMTokenList
- DocumentFragment
- DocumentType
- Event
- EventInit
- EventTarget
- HTMLCollection
- MutationObserver
- Node
- NodeList
- ProcessingInstruction
- Text
- XMLDocument
- addEventListener(type, callback)
- adopting steps
- appendChild(node)
- case-sensitively
- childNodes
- classList
- className
- cloneNode()
- cloning steps
- converted to ascii lowercase
- converted to ascii uppercase
- createDocument(namespace, qualifiedName)
- createElement(localName)
- createElementNS(namespace, qualifiedName)
- createHTMLDocument()
- currentTarget
- data
- event
- getElementById(elementId)
- getElementsByClassName(classNames)
- id
- importNode(node, deep)
- initEvent(type, bubbles, cancelable)
- initialize
- insertBefore(node, child)
- isTrusted
- item(index)
- localName
- namespaceURI
- node document
- other applicable specifications
- ownerDocument
- parentNode
- removing steps
- select
- tagName
- target
- textContent
- traverse
- type
- value
- [EVENTSOURCE] defines the following terms:
- [FILEAPI] defines the following terms:
- [FULLSCREEN] defines the following terms:
- [GEOMETRY-1] defines the following terms:
- [HR-TIME-2] defines the following terms:
-
[HTML] defines the following terms:
- BlobCallback
- CanPlayTypeResult
- Document
- DocumentReadyState
- DragEventInit
- ErrorEventInit
- EventHandler
- EventHandlerNonNull
- FrameRequestCallback
- FunctionStringCallback
- HashChangeEventInit
- ImageBitmapSource
- MediaProvider
- OnBeforeUnloadEventHandler
- OnBeforeUnloadEventHandlerNonNull
- OnErrorEventHandler
- OnErrorEventHandlerNonNull
- PageTransitionEventInit
- PopStateEventInit
- PromiseRejectionEventInit
- RelatedEventInit
- RenderingContext
- ScrollRestoration
- SelectionMode
- TextTrackKind
- TextTrackMode
- TrackEventInit
- activeElement
- addTextTrack(kind, label)
- blob
- blur()
- cite
- click()
- colno
- cols
- contentDocument
- contentWindow
- data
- dataTransfer
- dataset
- defaultPlaybackRate
- defaultView
- dir
- ended
- error
- filename
- focus()
- forceSpellCheck()
- height
- hidden
- lang
- lineno
- media
- message
- name
- networkState
- newURL
- noShade
- oldURL
- open(url, target, features)
- pause()
- paused
- persisted
- play()
- playbackRate
- played
- poster
- promise
- reason
- relatedTarget
- rows
- sizes
- spellcheck
- src
- srcset
- state
- tabIndex
- title
- toDataURL(type)
- track
- translate
- type
- typeMustMatch
- value
- width
- [html-ls] defines the following terms:
- [JLREQ] defines the following terms:
- [MATHML] defines the following terms:
- [MEDIACAPTURE-STREAMS] defines the following terms:
- [mediaqueries-4] defines the following terms:
- [mediasource] defines the following terms:
- [PAGE-VISIBILITY] defines the following terms:
- [PROGRESS-EVENTS] defines the following terms:
- [promises-guide] defines the following terms:
- [RFC5988] defines the following terms:
- [COOKIES] defines the following terms:
- [RFC6266] defines the following terms:
- [rfc7230] defines the following terms:
- [rfc7231] defines the following terms:
- [rfc7232] defines the following terms:
- [rfc7234] defines the following terms:
- [selectors-4] defines the following terms:
- [SVG] defines the following terms:
- [SVG2] defines the following terms:
- [SVGTiny12] defines the following terms:
- [TOUCH-EVENTS] defines the following terms:
- [URL] defines the following terms:
- [WEBGL] defines the following terms:
-
[WEBIDL] defines the following terms:
- AbortError
- DOMException
- DOMString
- DataCloneError
- EmptyString
- Exposed
- HierarchyRequestError
- IndexSizeError
- InvalidAccessError
- InvalidCharacterError
- InvalidModificationError
- InvalidNodeTypeError
- InvalidStateError
- LegacyUnenumerableNamedProperties
- LenientThis
- NamespaceError
- NetworkError
- NoInterfaceObject
- NoModificationAllowedError
- NotFoundError
- NotSupportedError
- OverrideBuiltins
- PrimaryGlobal
- Promise
- PutForwards
- QuotaExceededError
- Replaceable
- SameObject
- SecurityError
- TimeoutError
- TreatNonObjectAsNull
- TreatNullAs
- URLMismatchError
- Unforgeable
- WrongDocumentError
- array index property name
- arraybufferview
- callback this value
- converted
- converting
- determine the value of a named property
- determine the value of an indexed property
- global environment associated with
- invoke the web idl callback function
- perform a security check
- platform object
- read only
- support named properties
- supported property indices
- supported property names
- unenumerable
- [XHR] defines the following terms:
- [XML] defines the following terms:
- [XML-STYLESHEET] defines the following terms:
Elements
This section is non-normative.
An asterisk (*) in a cell indicates that the actual rules are more complicated than indicated in the table above.
† Categories in the "Parents" column refer to parents that list
the given categories in their content model, not to elements that themselves are in those
categories. For example, the a
element’s "Parents" column says "phrasing", so any
element whose content model contains the "phrasing" category could be a parent of an a
element. Since the "flow" category includes all the "phrasing" elements, that means
the th
element could be a parent to an a
element.
Element content categories
This section is non-normative.
* The tabindex
attribute can also make any element into interactive content.
Attributes
This section is non-normative.
Attribute | Element(s) | Description | Value |
---|---|---|---|
abbr
| th
| Alternative label to use for the header cell when referencing the cell in other contexts | Text* |
accept
| input
| Hint for expected file type in file upload controls | Set of comma-separated tokens* consisting of valid MIME types with no parameters or audio/* , video/* , or image/*
|
accept-charset
| form
| Character encodings to use for form submission | Ordered set of unique space-separated tokens, ASCII case-insensitive, consisting of labels of ASCII-compatible encodings* |
accesskey
| HTML elements | Keyboard shortcut to activate or focus element | Ordered set of unique space-separated tokens, case-sensitive, consisting of one Unicode code point in length |
action
| form
| URL to use for form submission | Valid non-empty URL potentially surrounded by spaces |
allowfullscreen
| iframe
| Whether to allow the iframe 's contents to use requestFullscreen()
| Boolean attribute |
alt
| area ; img ; input
| Replacement text for use when images are not available | Text* |
async
| script
| Execute script asynchronously | Boolean attribute |
autocomplete
| form
| Default setting for autofill feature for controls in the form | "on "; "off "
|
autocomplete
| input ; select ; textarea
| Hint for form autofill feature | Autofill field name and related tokens* |
autofocus
| button ; input ; keygen ; select ; textarea
| Automatically focus the form control when the page is loaded | Boolean attribute |
autoplay
| audio ; video
| Hint that the media resource can be started automatically when the page is loaded | Boolean attribute |
border
| table
| Explicit indication that the table element is not being used for layout purposes
| The empty string, or "1 "
|
challenge
| keygen
| String to package with the generated and signed public key | Text |
charset
| meta
| Character encoding declaration | Encoding label* |
charset
| script
| Character encoding of the external script resource | Encoding label* |
checked
| menuitem ; input
| Whether the command or control is checked | Boolean attribute |
cite
| blockquote ; del ; ins ; q
| Link to the source of the quotation or more information about the edit | Valid URL potentially surrounded by spaces |
class
| HTML elements | Classes to which the element belongs | Set of space-separated tokens |
cols
| textarea
| Maximum number of characters per line | Valid non-negative integer greater than zero |
colspan
| td ; th
| Number of columns that the cell is to span | Valid non-negative integer greater than zero |
command
| menuitem
| Command definition | ID* |
content
| meta
| Value of the element | Text* |
contenteditable
| HTML elements | Whether the element is editable | "true "; "false "
|
contextmenu
| HTML elements | The element’s context menu | ID* |
controls
| audio ; video
| Show user agent controls | Boolean attribute |
coords
| area
| Coordinates for the shape to be created in an image map | Valid list of floating-point numbers* |
crossorigin
| audio ; img ; link ; script ; video
| How the element handles crossorigin requests | "anonymous "; "use-credentials "
|
data
| object
| Address of the resource | Valid non-empty URL potentially surrounded by spaces |
datetime
| del ; ins
| Date and (optionally) time of the change | Valid date string with optional time |
datetime
| time
| Machine-readable value | Valid month string, valid date string, valid yearless date string, valid time string, valid floating date and time string, valid time-zone offset string, valid global date and time string, valid week string, valid non-negative integer, or valid duration string |
default
| menuitem
| Mark the command as being a default command | Boolean attribute |
default
| track
| Enable the track if no other text track is more suitable | Boolean attribute |
defer
| script
| Defer script execution | Boolean attribute |
dir
| HTML elements | The text directionality of the element | "ltr "; "rtl "; "auto "
|
dir
| bdo
| The text directionality of the element | "ltr "; "rtl "
|
dirname
| input ; textarea
| Name of form field to use for sending the element’s directionality in form submission | Text* |
disabled
| button ; menuitem ; fieldset ; input ; keygen ; optgroup ; option ; select ; textarea
| Whether the form control is disabled | Boolean attribute |
download
| a ; area
| Whether to download the resource instead of navigating to it, and its file name if so | Text |
draggable
| HTML elements | Whether the element is draggable | "true "; "false "
|
dropzone
| HTML elements | Accepted item types for drag-and-drop | Unordered set of unique space-separated tokens, ASCII case-insensitive, consisting of accepted types and drag feedback* |
enctype
| form
| Form data set encoding type to use for form submission | "application/x-www-form-urlencoded "; "multipart/form-data "; "text/plain "
|
for
| label
| Associate the label with form control | ID* |
for
| output
| Specifies controls from which the output was calculated | Unordered set of unique space-separated tokens, case-sensitive, consisting of IDs* |
form
| button ; fieldset ; input ; keygen ; label ; object ; output ; select ; textarea
| Associates the control with a form element
| ID* |
formaction
| button ; input
| URL to use for form submission | Valid non-empty URL potentially surrounded by spaces |
formenctype
| button ; input
| Form data set encoding type to use for form submission | "application/x-www-form-urlencoded "; "multipart/form-data "; "text/plain "
|
formmethod
| button ; input
| HTTP method to use for form submission | "GET "; "POST "
|
formnovalidate
| button ; input
| Bypass form control validation for form submission | Boolean attribute |
formtarget
| button ; input
| Browsing context for form submission | Valid browsing context name or keyword |
headers
| td ; th
| The header cells for this cell | Unordered set of unique space-separated tokens, case-sensitive, consisting of IDs* |
height
| canvas ; embed ; iframe ; img ; input ; object ; video
| Vertical dimension | Valid non-negative integer |
hidden
| HTML elements | Whether the element is relevant | Boolean attribute |
high
| meter
| Low limit of high range | Valid floating-point number* |
href
| a ; area
| Address of the hyperlink | Valid URL potentially surrounded by spaces |
href
| link
| Address of the hyperlink | Valid non-empty URL potentially surrounded by spaces |
href
| base
| Document base URL | Valid URL potentially surrounded by spaces |
hreflang
| a ; area ; link
| Language of the linked resource | Valid BCP 47 language tag |
http-equiv
| meta
| Pragma directive | Text* |
icon
| menuitem
| Icon for the command | Valid non-empty URL potentially surrounded by spaces |
id
| HTML elements | The element’s ID | Text* |
inputmode
| input ; textarea
| Hint for selecting an input modality | "verbatim "; "latin "; "latin-name "; "latin-prose "; "full-width-latin "; "kana "; "kana-name "; "katakana "; "numeric "; "tel "; "email "; "url "
|
ismap
| img
| Whether the image is a server-side image map | Boolean attribute |
keytype
| keygen
| The type of cryptographic key to generate | Text* |
kind
| track
| The type of text track | "subtitles "; "captions "; "descriptions "; "chapters "; "metadata "
|
label
| menuitem ; menu ; optgroup ; option ; track
| User-visible label | Text |
lang
| HTML elements | Language of the element | Valid BCP 47 language tag or the empty string |
list
| input
| List of autocomplete options | ID* |
loop
| audio ; video
| Whether to loop the media resource | Boolean attribute |
low
| meter
| High limit of low range | Valid floating-point number* |
max
| input
| Maximum value | Varies* |
max
| meter ; progress
| Upper bound of range | Valid floating-point number* |
maxlength
| input ; textarea
| Maximum length of value | Valid non-negative integer |
media
| link ; style
| Applicable media | Valid media query list |
menu
| button
| Specifies the element’s designated pop-up menu | ID* |
method
| form
| HTTP method to use for form submission | "get "; "post "
|
min
| input
| Minimum value | Varies* |
min
| meter
| Lower bound of range | Valid floating-point number* |
minlength
| input ; textarea
| Minimum length of value | Valid non-negative integer |
multiple
| input ; select
| Whether to allow multiple values | Boolean attribute |
muted
| audio ; video
| Whether to mute the media resource by default | Boolean attribute |
name
| button ; fieldset ; input ; keygen ; output ; select ; textarea
| Name of form control to use for form submission and in the form.elements API
| Text* |
name
| form
| Name of form to use in the document.forms API
| Text* |
name
| iframe ; object
| Name of nested browsing context | Valid browsing context name or keyword |
name
| map
| Name of image map to reference from the usemap attribute
| Text* |
name
| meta
| Metadata name | Text* |
name
| param
| Name of parameter | Text |
nonce
| script ; style
| Cryptographic nonce used in Content Security Policy checks [CSP3] | Text |
novalidate
| form
| Bypass form control validation for form submission | Boolean attribute |
open
| details
| Whether the details are visible | Boolean attribute |
optimum
| meter
| Optimum value in gauge | Valid floating-point number* |
pattern
| input
| Pattern to be matched by the form control’s value | Regular expression matching the JavaScript Pattern production |
placeholder
| input ; textarea
| User-visible label to be placed within the form control | Text* |
poster
| video
| Poster frame to show prior to video playback | Valid non-empty URL potentially surrounded by spaces |
preload
| audio ; video
| Hints how much buffering the media resource will likely need | "none "; "metadata "; "auto "
|
radiogroup
| menuitem
| Name of group of commands to treat as a radio button group | Text |
readonly
| input ; textarea
| Whether to allow the value to be edited by the user | Boolean attribute |
rel
| a ; area ; link
| Relationship of this document (or subsection/topic) to the destination resource | Set of space-separated tokens* |
required
| input ; select ; textarea
| Whether the control is required for form submission | Boolean attribute |
rev
| a ; link
| Reverse link relationship of the destination resource to this document (or subsection/topic) | Set of space-separated tokens |
reversed
| ol
| Number the list backwards | Boolean attribute |
rows
| textarea
| Number of lines to show | Valid non-negative integer greater than zero |
rowspan
| td ; th
| Number of rows that the cell is to span | Valid non-negative integer |
sandbox
| iframe
| Security rules for nested content | Unordered set of unique space-separated tokens, ASCII case-insensitive, consisting of
"allow-forms ",
"allow-pointer-lock ",
"allow-popups ",
"allow-same-origin ",
"allow-scripts and
"allow-top-navigation "
|
spellcheck
| HTML elements | Whether the element is to have its spelling and grammar checked | "true "; "false "
|
scope
| th
| Specifies which cells the header cell applies to | "row "; "col "; "rowgroup "; "colgroup "
|
selected
| option
| Whether the option is selected by default | Boolean attribute |
shape
| area
| The kind of shape to be created in an image map | "circle "; "default "; "poly "; "rect "
|
size
| input ; select
| Size of the control | Valid non-negative integer greater than zero |
sizes
| link
| Sizes of the icons (for rel ="icon ")
| Unordered set of unique space-separated tokens, ASCII case-insensitive, consisting of sizes* |
sizes
| img ; source
| Image sizes for different page layouts | Valid source size list |
span
| col ; colgroup
| Number of columns spanned by the element | Valid non-negative integer greater than zero |
src
| audio ; embed ; iframe ; img ; input ; script ; source ; track ; video
| Address of the resource | Valid non-empty URL potentially surrounded by spaces |
srcdoc
| iframe
| A document to render in the iframe
| The source of an iframe srcdoc document*
|
srclang
| track
| Language of the text track | Valid BCP 47 language tag |
srcset
| img ; source
| Images to use in different situations (e.g., high-resolution displays, small monitors, etc) | Comma-separated list of image candidate strings |
start
| ol
| Ordinal value of the first item | Valid integer |
step
| input
| Granularity to be matched by the form control’s value | Valid floating-point number greater than zero, or "any "
|
style
| HTML elements | Presentational and formatting instructions | CSS declarations* |
tabindex
| HTML elements | Whether the element is focusable, and the relative order of the element for the purposes of sequential focus navigation | Valid integer |
target
| a ; area
| Browsing context for hyperlink navigation | Valid browsing context name or keyword |
target
| base
| Default browsing context for hyperlink navigation and form submission | Valid browsing context name or keyword |
target
| form
| Browsing context for form submission | Valid browsing context name or keyword |
title
| HTML elements | Advisory information for the element | Text |
title
| abbr ; dfn
| Full term or expansion of abbreviation | Text |
title
| input
| Description of pattern (when used with pattern attribute)
| Text |
title
| menuitem
| Hint describing the command | Text |
title
| link
| Title of the link | Text |
title
| link ; style
| Alternative style sheet set name | Text |
translate
| HTML elements | Whether the element is to be translated when the page is localized | "yes "; "no "
|
type
| a ; area ; link
| Hint for the type of the referenced resource | Valid MIME type |
type
| button
| Type of button | "submit "; "reset "; "button "; "menu "
|
type
| embed ; object ; script ; source ; style
| Type of embedded resource | Valid MIME type |
type
| input
| Type of form control | input type keyword
|
type
| menu
| Type of menu | "context ";
|
type
| menuitem
| Type of command | "command "; "checkbox "; "radio "
|
type
| ol
| Kind of list marker | "1 "; "a "; "A "; "i "; "I "
|
typemustmatch
| object
| Whether the type attribute and the Content-Type value need to match for the resource to be used
| Boolean attribute |
usemap
| img
| Name of image map to use | Valid hash-name reference* |
value
| button ; option
| Value to be used for form submission | Text |
value
| data
| Machine-readable value | Text* |
value
| input
| Value of the form control | Varies* |
value
| li
| Ordinal value of the list item | Valid integer |
value
| meter ; progress
| Current value of the element | Valid floating-point number |
value
| param
| Value of parameter | Text |
width
| canvas ; embed ; iframe ; img ; input ; object ; video
| Horizontal dimension | Valid non-negative integer |
wrap
| textarea
| How the value of the form control is to be wrapped for form submission | "soft "; "hard "
|
An asterisk (*) in a cell indicates that the actual rules are more complicated than indicated in the table above.
Element Interfaces
This section is non-normative.
Events
This section is non-normative.
Event | Interface | Interesting targets | Description |
---|---|---|---|
abort
| Event
| Window
| Fired at the Window when the download was aborted by the user
|
DOMContentLoaded
| Event
| Document
| Fired at the Document once the parser has finished
|
afterprint
| Event
| Window
| Fired at the Window after printing
|
afterscriptexecute
| Event
| script elements
| Fired at script elements after the script runs (just before the corresponding load event)
|
beforeprint
| Event
| Window
| Fired at the Window before printing
|
beforescriptexecute
| Event
| script elements
| Fired at script elements just before the script runs; canceling the event cancels the running of the script
|
beforeunload
| BeforeUnloadEvent
| Window
| Fired at the Window when the page is about to be unloaded, in case the page would like to show a warning prompt
|
blur
| Event
| Window , elements
| Fired at nodes losing focus |
change
| Event
| Form controls | Fired at controls when the user commits a value change (see also the change event of input elements)
|
click
| MouseEvent
| Elements | Normally a mouse event; also synthetically fired at an element before its activation behavior is run, when an element is activated from a non-pointer input device (e.g., a keyboard) |
contextmenu
| Event
| Elements | Fired at elements when the user requests their context menu |
copy
| Event
| Elements | Fired at elements when the user copies data to the clipboard |
cut
| Event
| Elements | Fired at elements when the user copies the selected data on the clipboard and removes the selection from the document |
error
| Event
| Global scope objects, Worker objects, elements, networking-related objects
| Fired when unexpected errors occur (e.g., networking errors, script errors, decoding errors) |
focus
| Event
| Window , elements
| Fired at nodes gaining focus |
hashchange
| HashChangeEvent
| Window
| Fired at the Window when the fragment identifier part of the document’s address changes
|
input
| Event
| Form controls | Fired at controls when the user changes the value (see also the change event of input elements)
|
invalid
| Event
| Form controls | Fired at controls during form validation if they do not satisfy their constraints |
languagechange
| Event
| Global scope objects | Fired at the global scope object when the user’s preferred languages change |
load
| Event
| Window , elements
| Fired at the Window when the document has finished loading; fired at an element containing a resource (e.g., img , embed ) when its resource has finished loading
|
loadend
| Event or ProgressEvent
| img elements
| Fired at img elements after a successful load (see also media element events)
|
loadstart
| ProgressEvent
| img elements
| Fired at img elements when a load begins (see also media element events)
|
message
| MessageEvent
| Window , EventSource , WebSocket , MessagePort , DedicatedWorkerGlobalScope , Worker
| Fired at an object when it receives a message |
offline
| Event
| Global scope objects | Fired at the global scope object when the network connections fails |
online
| Event
| Global scope objects | Fired at the global scope object when the network connections returns |
open
| Event
| EventSource , WebSocket
| Fired at networking-related objects when a connection is established |
pagehide
| PageTransitionEvent
| Window
| Fired at the Window when the page’s entry in the session history stops being the current entry
|
pageshow
| PageTransitionEvent
| Window
| Fired at the Window when the page’s entry in the session history becomes the current entry
|
paste
| Event
| Elements | Fired at elements when the user will insert the clipboard data in the most suitable format (if any) supported for the given context |
popstate
| PopStateEvent
| Window
| Fired at the Window when the user navigates the session history
|
progress
| ProgressEvent
| img elements
| Fired at img elements during a CORS-same-origin image load (see also media element events)
|
readystatechange
| Event
| Document
| Fired at the Document when it finishes parsing and again when all its subresources have finished loading
|
reset
| Event
| form elements
| Fired at a form element when it is reset
|
select
| Event
| Form controls | Fired at form controls when their text selection is adjusted (whether by an API or by the user) |
show
| RelatedEvent
| menu elements
| Fired at a menu element when it is shown as a context menu
|
storage
| StorageEvent
| Window
| Fired at Window event when the corresponding localStorage or sessionStorage storage areas change
|
submit
| Event
| form elements
| Fired at a form element when it is submitted
|
toggle
| Event
| details element
| Fired at details elements when they open or close
|
unload
| Event
| Window
| Fired at the Window object when the page is going away
|
See also media element events, application cache events, and drag-and-drop events.
IDL Index
[LegacyUnenumerableNamedProperties] interface HTMLAllCollection { readonly attribute unsigned long length; getter Element? (unsigned long index); getter (HTMLCollection or Element)? namedItem(DOMString name); legacycaller (HTMLCollection or Element)? item(optional DOMString nameOrItem); }; interface HTMLFormControlsCollection : HTMLCollection { // inherits length and item() getter (RadioNodeList or Element)? namedItem(DOMString name); // shadows inherited namedItem() }; interface RadioNodeList : NodeList { attribute DOMString value; }; interface HTMLOptionsCollection : HTMLCollection { // inherits item(), namedItem() attribute unsigned long length; // shadows inherited length setter void (unsigned long index, HTMLOptionElement? option); void add((HTMLOptionElement or HTMLOptGroupElement) element, optional (HTMLElement or long)? before = null); void remove(long index); attribute long selectedIndex; }; [OverrideBuiltins] interface DOMStringMap { getter DOMString (DOMString name); setter void (DOMString name, DOMString value); deleter void (DOMString name); }; interface DOMElementMap { getter Element (DOMString name); setter creator void (DOMString name, Element value); deleter void (DOMString name); }; enum DocumentReadyState { "loading", "interactive", "complete" }; [OverrideBuiltins] partial /*sealed*/ interface Document { // resource metadata management [PutForwards=href, Unforgeable] readonly attribute Location? location; attribute DOMString domain; readonly attribute DOMString referrer; attribute DOMString cookie; readonly attribute DOMString lastModified; readonly attribute DocumentReadyState readyState; // DOM tree accessors getter object (DOMString name); attribute DOMString title; attribute DOMString dir; attribute HTMLElement? body; readonly attribute HTMLHeadElement? head; [SameObject] readonly attribute HTMLCollection images; [SameObject] readonly attribute HTMLCollection embeds; [SameObject] readonly attribute HTMLCollection plugins; [SameObject] readonly attribute HTMLCollection links; [SameObject] readonly attribute HTMLCollection forms; [SameObject] readonly attribute HTMLCollection scripts; NodeList getElementsByName(DOMString elementName); readonly attribute HTMLScriptElement? currentScript; // dynamic markup insertion Document open(optional DOMString type = "text/html", optional DOMString replace = ""); WindowProxy open(DOMString url, DOMString name, DOMString features, optional boolean replace = false); void close(); void write(DOMString... text); void writeln(DOMString... text); // user interaction readonly attribute WindowProxy? defaultView; readonly attribute Element? activeElement; boolean hasFocus(); attribute DOMString designMode; boolean execCommand(DOMString commandId, optional boolean showUI = false, optional DOMString value = ""); boolean queryCommandEnabled(DOMString commandId); boolean queryCommandIndeterm(DOMString commandId); boolean queryCommandState(DOMString commandId); boolean queryCommandSupported(DOMString commandId); DOMString queryCommandValue(DOMString commandId); // special event handler IDL attributes that only apply to Document objects [LenientThis] attribute EventHandler onreadystatechange; }; Document implements GlobalEventHandlers; Document implements DocumentAndElementEventHandlers; partial interface XMLDocument { boolean load(DOMString url); }; interface HTMLElement : Element { // metadata attributes attribute DOMString title; attribute DOMString lang; attribute boolean translate; attribute DOMString dir; [SameObject] readonly attribute DOMStringMap dataset; // user interaction attribute boolean hidden; void click(); attribute long tabIndex; void focus(); void blur(); attribute DOMString accessKey; attribute boolean draggable; [PutForwards=value] readonly attribute DOMTokenList dropzone; attribute HTMLMenuElement? contextMenu; attribute boolean spellcheck; void forceSpellCheck(); }; HTMLElement implements GlobalEventHandlers; HTMLElement implements DocumentAndElementEventHandlers; HTMLElement implements ElementContentEditable; interface HTMLUnknownElement : HTMLElement { }; interface HTMLHtmlElement : HTMLElement {}; interface HTMLHeadElement : HTMLElement {}; interface HTMLTitleElement : HTMLElement { attribute DOMString text; }; interface HTMLBaseElement : HTMLElement { attribute DOMString href; attribute DOMString target; }; interface HTMLLinkElement : HTMLElement { attribute DOMString href; attribute DOMString? crossOrigin; attribute DOMString rel; attribute DOMString rev; [SameObject, PutForwards=value]readonly attribute DOMTokenList relList; attribute DOMString media; attribute DOMString hreflang; attribute DOMString type; [SameObject, PutForwards=value] readonly attribute DOMTokenList sizes; }; HTMLLinkElement implements LinkStyle; interface HTMLMetaElement : HTMLElement { attribute DOMString name; attribute DOMString httpEquiv; attribute DOMString content; }; interface HTMLStyleElement : HTMLElement { attribute DOMString media; attribute DOMString nonce; attribute DOMString type; }; HTMLStyleElement implements LinkStyle; interface HTMLBodyElement : HTMLElement { }; HTMLBodyElement implements WindowEventHandlers; interface HTMLHeadingElement : HTMLElement {}; interface HTMLParagraphElement : HTMLElement {}; interface HTMLHRElement : HTMLElement {}; interface HTMLPreElement : HTMLElement {}; interface HTMLQuoteElement : HTMLElement { attribute DOMString cite; }; interface HTMLOListElement : HTMLElement { attribute boolean reversed; attribute long start; attribute DOMString type; }; interface HTMLUListElement : HTMLElement {}; interface HTMLLIElement : HTMLElement { attribute long value; }; interface HTMLDListElement : HTMLElement {}; interface HTMLDivElement : HTMLElement {}; interface HTMLAnchorElement : HTMLElement { attribute DOMString target; attribute DOMString download; attribute DOMString rel; attribute DOMString rev; [SameObject, PutForwards=value] readonly attribute DOMTokenList relList; attribute DOMString hreflang; attribute DOMString type; attribute DOMString text; }; HTMLAnchorElement implements HTMLHyperlinkElementUtils; interface HTMLDataElement : HTMLElement { attribute DOMString value; }; interface HTMLTimeElement : HTMLElement { attribute DOMString dateTime; }; interface HTMLSpanElement : HTMLElement {}; interface HTMLBRElement : HTMLElement {}; interface HTMLModElement : HTMLElement { attribute DOMString cite; attribute DOMString dateTime; }; interface HTMLPictureElement : HTMLElement {}; partial interface HTMLSourceElement { attribute DOMString srcset; attribute DOMString sizes; attribute DOMString media; }; [NamedConstructor=Image(optional unsigned long width, optional unsigned long height)] interface HTMLImageElement : HTMLElement { attribute DOMString alt; attribute DOMString src; attribute DOMString srcset; attribute DOMString sizes; attribute DOMString? crossOrigin; attribute DOMString useMap; attribute boolean isMap; attribute unsigned long width; attribute unsigned long height; readonly attribute unsigned long naturalWidth; readonly attribute unsigned long naturalHeight; readonly attribute boolean complete; readonly attribute DOMString currentSrc; }; interface HTMLIFrameElement : HTMLElement { attribute DOMString src; attribute DOMString srcdoc; attribute DOMString name; [PutForwards=value] readonly attribute DOMTokenList sandbox; attribute boolean allowFullscreen; attribute DOMString width; attribute DOMString height; readonly attribute Document? contentDocument; readonly attribute WindowProxy? contentWindow; }; interface HTMLEmbedElement : HTMLElement { attribute DOMString src; attribute DOMString type; attribute DOMString width; attribute DOMString height; legacycaller any (any... arguments); }; interface HTMLObjectElement : HTMLElement { attribute DOMString data; attribute DOMString type; attribute boolean typeMustMatch; attribute DOMString name; readonly attribute HTMLFormElement? form; attribute DOMString width; attribute DOMString height; readonly attribute Document? contentDocument; readonly attribute WindowProxy? contentWindow; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); legacycaller any (any... arguments); }; interface HTMLParamElement : HTMLElement { attribute DOMString name; attribute DOMString value; }; interface HTMLVideoElement : HTMLMediaElement { attribute unsigned long width; attribute unsigned long height; readonly attribute unsigned long videoWidth; readonly attribute unsigned long videoHeight; attribute DOMString poster; }; [NamedConstructor=Audio(optional DOMString src)] interface HTMLAudioElement : HTMLMediaElement {}; interface HTMLSourceElement : HTMLElement { attribute DOMString src; attribute DOMString type; }; interface HTMLTrackElement : HTMLElement { attribute DOMString kind; attribute DOMString src; attribute DOMString srclang; attribute DOMString label; attribute boolean default; const unsigned short NONE = 0; const unsigned short LOADING = 1; const unsigned short LOADED = 2; const unsigned short ERROR = 3; readonly attribute unsigned short readyState; readonly attribute TextTrack track; }; enum CanPlayTypeResult { "" /* empty string */, "maybe", "probably" }; typedef (MediaStream or MediaSource or Blob) MediaProvider; interface HTMLMediaElement : HTMLElement { // error state readonly attribute MediaError? error; // network state attribute DOMString src; attribute MediaProvider? srcObject; readonly attribute DOMString currentSrc; attribute DOMString? crossOrigin; const unsigned short NETWORK_EMPTY = 0; const unsigned short NETWORK_IDLE = 1; const unsigned short NETWORK_LOADING = 2; const unsigned short NETWORK_NO_SOURCE = 3; readonly attribute unsigned short networkState; attribute DOMString preload; readonly attribute TimeRanges buffered; void load(); CanPlayTypeResult canPlayType(DOMString type); // ready state const unsigned short HAVE_NOTHING = 0; const unsigned short HAVE_METADATA = 1; const unsigned short HAVE_CURRENT_DATA = 2; const unsigned short HAVE_FUTURE_DATA = 3; const unsigned short HAVE_ENOUGH_DATA = 4; readonly attribute unsigned short readyState; readonly attribute boolean seeking; // playback state attribute double currentTime; void fastSeek(double time); readonly attribute unrestricted double duration; object getStartDate(); readonly attribute boolean paused; attribute double defaultPlaybackRate; attribute double playbackRate; readonly attribute TimeRanges played; readonly attribute TimeRanges seekable; readonly attribute boolean ended; attribute boolean autoplay; attribute boolean loop; void play(); void pause(); // controls attribute boolean controls; attribute double volume; attribute boolean muted; attribute boolean defaultMuted; // tracks [SameObject] readonly attribute AudioTrackList audioTracks; [SameObject] readonly attribute VideoTrackList videoTracks; [SameObject] readonly attribute TextTrackList textTracks; TextTrack addTextTrack(TextTrackKind kind, optional DOMString label = "", optional DOMString language = ""); }; interface MediaError { const unsigned short MEDIA_ERR_ABORTED = 1; const unsigned short MEDIA_ERR_NETWORK = 2; const unsigned short MEDIA_ERR_DECODE = 3; const unsigned short MEDIA_ERR_SRC_NOT_SUPPORTED = 4; readonly attribute unsigned short code; }; interface AudioTrackList : EventTarget { readonly attribute unsigned long length; getter AudioTrack (unsigned long index); AudioTrack? getTrackById(DOMString id); attribute EventHandler onchange; attribute EventHandler onaddtrack; attribute EventHandler onremovetrack; }; interface AudioTrack { readonly attribute DOMString id; readonly attribute DOMString kind; readonly attribute DOMString label; readonly attribute DOMString language; attribute boolean enabled; }; interface VideoTrackList : EventTarget { readonly attribute unsigned long length; getter VideoTrack (unsigned long index); VideoTrack? getTrackById(DOMString id); readonly attribute long selectedIndex; attribute EventHandler onchange; attribute EventHandler onaddtrack; attribute EventHandler onremovetrack; }; interface VideoTrack { readonly attribute DOMString id; readonly attribute DOMString kind; readonly attribute DOMString label; readonly attribute DOMString language; attribute boolean selected; }; interface TextTrackList : EventTarget { readonly attribute unsigned long length; getter TextTrack (unsigned long index); TextTrack? getTrackById(DOMString id); attribute EventHandler onchange; attribute EventHandler onaddtrack; attribute EventHandler onremovetrack; }; enum TextTrackMode { "disabled", "hidden", "showing" }; enum TextTrackKind { "subtitles", "captions", "descriptions", "chapters", "metadata" }; interface TextTrack : EventTarget { readonly attribute TextTrackKind kind; readonly attribute DOMString label; readonly attribute DOMString language; readonly attribute DOMString id; readonly attribute DOMString inBandMetadataTrackDispatchType; attribute TextTrackMode mode; readonly attribute TextTrackCueList? cues; readonly attribute TextTrackCueList? activeCues; void addCue(TextTrackCue cue); void removeCue(TextTrackCue cue); attribute EventHandler oncuechange; }; interface TextTrackCueList { readonly attribute unsigned long length; getter TextTrackCue (unsigned long index); TextTrackCue? getCueById(DOMString id); }; interface TextTrackCue : EventTarget { readonly attribute TextTrack? track; attribute DOMString id; attribute double startTime; attribute double endTime; attribute boolean pauseOnExit; attribute EventHandler onenter; attribute EventHandler onexit; }; [Constructor(double startTime, double endTime, ArrayBuffer data)] interface DataCue : TextTrackCue { attribute ArrayBuffer data; }; interface TimeRanges { readonly attribute unsigned long length; double start(unsigned long index); double end(unsigned long index); }; [Constructor(DOMString type, optional TrackEventInit eventInitDict)] interface TrackEvent : Event { readonly attribute (VideoTrack or AudioTrack or TextTrack)? track; }; dictionary TrackEventInit : EventInit { (VideoTrack or AudioTrack or TextTrack)? track; }; interface HTMLMapElement : HTMLElement { attribute DOMString name; [SameObject] readonly attribute HTMLCollection areas; [SameObject] readonly attribute HTMLCollection images; }; interface HTMLAreaElement : HTMLElement { attribute DOMString alt; attribute DOMString coords; attribute DOMString shape; attribute DOMString target; attribute DOMString download; attribute DOMString rel; readonly attribute DOMTokenList relList; attribute DOMString hreflang; attribute DOMString type; }; HTMLAreaElement implements HTMLHyperlinkElementUtils; [NoInterfaceObject] interface HTMLHyperlinkElementUtils { stringifier attribute USVString href; readonly attribute USVString origin; attribute USVString protocol; attribute USVString username; attribute USVString password; attribute USVString host; attribute USVString hostname; attribute USVString port; attribute USVString pathname; attribute USVString search; attribute USVString hash; }; interface HTMLTableElement : HTMLElement { attribute HTMLTableCaptionElement? caption; HTMLTableCaptionElement createCaption(); void deleteCaption(); attribute HTMLTableSectionElement? tHead; HTMLTableSectionElement createTHead(); void deleteTHead(); attribute HTMLTableSectionElement? tFoot; HTMLTableSectionElement createTFoot(); void deleteTFoot(); [SameObject] readonly attribute HTMLCollection tBodies; HTMLTableSectionElement createTBody(); [SameObject] readonly attribute HTMLCollection rows; HTMLTableRowElement insertRow(optional long index = -1); void deleteRow(long index); }; interface HTMLTableCaptionElement : HTMLElement {}; interface HTMLTableColElement : HTMLElement { attribute unsigned long span; }; interface HTMLTableSectionElement : HTMLElement { [SameObject] readonly attribute HTMLCollection rows; HTMLElement insertRow(optional long index = -1); void deleteRow(long index); }; interface HTMLTableRowElement : HTMLElement { readonly attribute long rowIndex; readonly attribute long sectionRowIndex; [SameObject] readonly attribute HTMLCollection cells; HTMLElement insertCell(optional long index = -1); void deleteCell(long index); }; interface HTMLTableDataCellElement : HTMLTableCellElement {}; interface HTMLTableHeaderCellElement : HTMLTableCellElement { attribute DOMString scope; attribute DOMString abbr; }; interface HTMLTableCellElement : HTMLElement { attribute unsigned long colSpan; attribute unsigned long rowSpan; [PutForwards=value] readonly attribute DOMTokenList headers; readonly attribute long cellIndex; }; [OverrideBuiltins] interface HTMLFormElement : HTMLElement { attribute DOMString acceptCharset; attribute DOMString action; attribute DOMString autocomplete; attribute DOMString enctype; attribute DOMString encoding; attribute DOMString method; attribute DOMString name; attribute boolean noValidate; attribute DOMString target; [SameObject] readonly attribute HTMLFormControlsCollection elements; readonly attribute unsigned long length; getter Element (unsigned long index); getter (RadioNodeList or Element) (DOMString name); void submit(); void reset(); boolean checkValidity(); boolean reportValidity(); }; interface HTMLLabelElement : HTMLElement { readonly attribute HTMLFormElement? form; attribute DOMString htmlFor; readonly attribute HTMLElement? control; }; interface HTMLInputElement : HTMLElement { attribute DOMString accept; attribute DOMString alt; attribute DOMString autocomplete; attribute boolean autofocus; attribute boolean defaultChecked; attribute boolean checked; attribute DOMString dirName; attribute boolean disabled; readonly attribute HTMLFormElement? form; readonly attribute FileList? files; attribute DOMString formAction; attribute DOMString formEnctype; attribute DOMString formMethod; attribute boolean formNoValidate; attribute DOMString formTarget; attribute unsigned long height; attribute boolean indeterminate; attribute DOMString inputMode; readonly attribute HTMLElement? list; attribute DOMString max; attribute long maxLength; attribute DOMString min; attribute long minLength; attribute boolean multiple; attribute DOMString name; attribute DOMString pattern; attribute DOMString placeholder; attribute boolean readOnly; attribute boolean required; attribute unsigned long size; attribute DOMString src; attribute DOMString step; attribute DOMString type; attribute DOMString defaultValue; [TreatNullAs=EmptyString] attribute DOMString value; attribute object? valueAsDate; attribute unrestricted double valueAsNumber; attribute unsigned long width; void stepUp(optional long n = 1); void stepDown(optional long n = 1); readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; void select(); attribute unsigned long selectionStart; attribute unsigned long selectionEnd; attribute DOMString selectionDirection; void setRangeText(DOMString replacement); void setRangeText(DOMString replacement, unsigned long start, unsigned long end, optional SelectionMode selectionMode = "preserve"); void setSelectionRange(unsigned long start, unsigned long end, optional DOMString direction); }; interface HTMLButtonElement : HTMLElement { attribute boolean autofocus; attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute DOMString formAction; attribute DOMString formEnctype; attribute DOMString formMethod; attribute boolean formNoValidate; attribute DOMString formTarget; attribute DOMString name; attribute DOMString type; attribute DOMString value; attribute HTMLMenuElement? menu; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; }; interface HTMLSelectElement : HTMLElement { attribute DOMString autocomplete; attribute boolean autofocus; attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute boolean multiple; attribute DOMString name; attribute boolean required; attribute unsigned long size; readonly attribute DOMString type; [SameObject] readonly attribute HTMLOptionsCollection options; attribute unsigned long length; getter Element? item(unsigned long index); HTMLOptionElement? namedItem(DOMString name); void add((HTMLOptionElement or HTMLOptGroupElement) element, optional (HTMLElement or long)? before = null); void remove(); // ChildNode overload void remove(long index); setter void (unsigned long index, HTMLOptionElement? option); [SameObject] readonly attribute HTMLCollection selectedOptions; attribute long selectedIndex; attribute DOMString value; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; }; interface HTMLDataListElement : HTMLElement { [SameObject] readonly attribute HTMLCollection options; }; interface HTMLOptGroupElement : HTMLElement { attribute boolean disabled; attribute DOMString label; }; [NamedConstructor=Option(optional DOMString text = "", optional DOMString value, optional boolean defaultSelected = false, optional boolean selected = false)] interface HTMLOptionElement : HTMLElement { attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute DOMString label; attribute boolean defaultSelected; attribute boolean selected; attribute DOMString value; attribute DOMString text; readonly attribute long index; }; interface HTMLTextAreaElement : HTMLElement { attribute DOMString autocomplete; attribute boolean autofocus; attribute unsigned long cols; attribute DOMString dirName; attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute DOMString inputMode; attribute long maxLength; attribute long minLength; attribute DOMString name; attribute DOMString placeholder; attribute boolean readOnly; attribute boolean required; attribute unsigned long rows; attribute DOMString wrap; readonly attribute DOMString type; attribute DOMString defaultValue; [TreatNullAs=EmptyString] attribute DOMString value; readonly attribute unsigned long textLength; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; void select(); attribute unsigned long selectionStart; attribute unsigned long selectionEnd; attribute DOMString selectionDirection; void setRangeText(DOMString replacement); void setRangeText(DOMString replacement, unsigned long start, unsigned long end, optional SelectionMode selectionMode = "preserve"); void setSelectionRange(unsigned long start, unsigned long end, optional DOMString direction); }; interface HTMLKeygenElement : HTMLElement { attribute boolean autofocus; attribute DOMString challenge; attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute DOMString keytype; attribute DOMString name; readonly attribute DOMString type; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; }; interface HTMLOutputElement : HTMLElement { [SameObject, PutForwards=value] readonly attribute DOMTokenList htmlFor; readonly attribute HTMLFormElement? form; attribute DOMString name; readonly attribute DOMString type; attribute DOMString defaultValue; attribute DOMString value; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); [SameObject] readonly attribute NodeList labels; }; interface HTMLProgressElement : HTMLElement { attribute double value; attribute double max; readonly attribute double position; [SameObject] readonly attribute NodeList labels; }; interface HTMLMeterElement : HTMLElement { attribute double value; attribute double min; attribute double max; attribute double low; attribute double high; attribute double optimum; [SameObject] readonly attribute NodeList labels; }; interface HTMLFieldSetElement : HTMLElement { attribute boolean disabled; readonly attribute HTMLFormElement? form; attribute DOMString name; readonly attribute DOMString type; [SameObject] readonly attribute HTMLCollection elements; readonly attribute boolean willValidate; [SameObject] readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); boolean reportValidity(); void setCustomValidity(DOMString error); }; interface HTMLLegendElement : HTMLElement { readonly attribute HTMLFormElement? form; }; enum SelectionMode { "select", "start", "end", "preserve" // default }; interface ValidityState { readonly attribute boolean valueMissing; readonly attribute boolean typeMismatch; readonly attribute boolean patternMismatch; readonly attribute boolean tooLong; readonly attribute boolean tooShort; readonly attribute boolean rangeUnderflow; readonly attribute boolean rangeOverflow; readonly attribute boolean stepMismatch; readonly attribute boolean badInput; readonly attribute boolean customError; readonly attribute boolean valid; }; interface HTMLDetailsElement : HTMLElement { attribute boolean open; }; interface HTMLMenuElement : HTMLElement { attribute DOMString type; attribute DOMString label; }; interface HTMLMenuItemElement : HTMLElement { attribute DOMString type; attribute DOMString label; attribute DOMString icon; attribute boolean disabled; attribute boolean checked; attribute DOMString radiogroup; attribute boolean default; }; [Constructor(DOMString type, optional RelatedEventInit eventInitDict)] interface RelatedEvent : Event { readonly attribute EventTarget? relatedTarget; }; dictionary RelatedEventInit : EventInit { EventTarget? relatedTarget; }; interface HTMLScriptElement : HTMLElement { attribute DOMString src; attribute DOMString type; attribute DOMString charset; attribute boolean async; attribute boolean defer; attribute DOMString? crossOrigin; attribute DOMString text; attribute DOMString nonce; }; interface HTMLTemplateElement : HTMLElement { readonly attribute DocumentFragment content; }; typedef (CanvasRenderingContext2D or WebGLRenderingContext) RenderingContext; interface HTMLCanvasElement : HTMLElement { attribute unsigned long width; attribute unsigned long height; RenderingContext? getContext(DOMString contextId, any... arguments); boolean probablySupportsContext(DOMString contextId, any... arguments); DOMString toDataURL(optional DOMString type, any... arguments); void toBlob(BlobCallback _callback, optional DOMString type, any... arguments); }; callback BlobCallback = void (Blob? blob); [NoInterfaceObject] interface ElementContentEditable { attribute DOMString contentEditable; readonly attribute boolean isContentEditable; }; interface DataTransfer { attribute DOMString dropEffect; attribute DOMString effectAllowed; [SameObject] readonly attribute DataTransferItemList items; void setDragImage(Element image, long x, long y); /* old interface */ [SameObject] readonly attribute DOMString[] types; DOMString getData(DOMString format); void setData(DOMString format, DOMString data); void clearData(optional DOMString format); [SameObject] readonly attribute FileList files; }; interface DataTransferItemList { readonly attribute unsigned long length; getter DataTransferItem (unsigned long index); DataTransferItem? add(DOMString data, DOMString type); DataTransferItem? add(File data); void remove(unsigned long index); void clear(); }; interface DataTransferItem { readonly attribute DOMString kind; readonly attribute DOMString type; void getAsString(FunctionStringCallback? _callback); File? getAsFile(); }; callback FunctionStringCallback = void (DOMString data); [Constructor(DOMString type, optional DragEventInit eventInitDict)] interface DragEvent : MouseEvent { readonly attribute DataTransfer? dataTransfer; }; dictionary DragEventInit : MouseEventInit { DataTransfer? dataTransfer = null; }; [PrimaryGlobal, LegacyUnenumerableNamedProperties] /*sealed*/ interface Window : EventTarget { // the current browsing context [Unforgeable] readonly attribute WindowProxy window; [Replaceable] readonly attribute WindowProxy self; [Unforgeable] readonly attribute Document document; attribute DOMString name; [PutForwards=href, Unforgeable] readonly attribute Location location; readonly attribute History history; [Replaceable] readonly attribute BarProp locationbar; [Replaceable] readonly attribute BarProp menubar; [Replaceable] readonly attribute BarProp personalbar; [Replaceable] readonly attribute BarProp scrollbars; [Replaceable] readonly attribute BarProp statusbar; [Replaceable] readonly attribute BarProp toolbar; attribute DOMString status; void close(); readonly attribute boolean closed; void stop(); void focus(); void blur(); // other browsing contexts [Replaceable] readonly attribute WindowProxy frames; [Replaceable] readonly attribute unsigned long length; [Unforgeable] readonly attribute WindowProxy top; attribute any opener; [Replaceable] readonly attribute WindowProxy parent; readonly attribute Element? frameElement; WindowProxy open(optional DOMString url = "about:blank", optional DOMString target = "_blank", [TreatNullAs=EmptyString] optional DOMString features = "", optional boolean replace = false); getter WindowProxy (unsigned long index); getter object (DOMString name); // the user agent readonly attribute Navigator navigator; // user prompts void alert(); void alert(DOMString message); boolean confirm(optional DOMString message = ""); DOMString? prompt(optional DOMString message = "", optional DOMString default = ""); void print(); any showModalDialog(DOMString url, optional any argument); // deprecated unsigned long requestAnimationFrame(FrameRequestCallback callback); void cancelAnimationFrame(unsigned long handle); }; Window implements GlobalEventHandlers; Window implements WindowEventHandlers; callback FrameRequestCallback = void (DOMHighResTimeStamp time); interface BarProp { readonly attribute boolean visible; }; enum ScrollRestoration { "auto", "manual" }; interface History { readonly attribute unsigned long length; attribute ScrollRestoration scrollRestoration; readonly attribute any state; void go(optional long delta = 0); void back(); void forward(); void pushState(any data, DOMString title, optional DOMString? url = null); void replaceState(any data, DOMString title, optional DOMString? url = null); }; [Unforgeable] interface Location { stringifier attribute USVString href; readonly attribute USVString origin; attribute USVString protocol; attribute USVString host; attribute USVString hostname; attribute USVString port; attribute USVString pathname; attribute USVString search; attribute USVString hash; void assign(USVString url); void replace(USVString url); void reload(); [SameObject] readonly attribute USVString[] ancestorOrigins; }; [Constructor(DOMString type, optional PopStateEventInit eventInitDict), Exposed=(Window,Worker)] interface PopStateEvent : Event { readonly attribute any state; }; dictionary PopStateEventInit : EventInit { any state; }; [Constructor(DOMString type, optional HashChangeEventInit eventInitDict), Exposed=(Window,Worker)] interface HashChangeEvent : Event { readonly attribute DOMString oldURL; readonly attribute DOMString newURL; }; dictionary HashChangeEventInit : EventInit { DOMString oldURL; DOMString newURL; }; [Constructor(DOMString type, optional PageTransitionEventInit eventInitDict), Exposed=(Window,Worker)] interface PageTransitionEvent : Event { readonly attribute boolean persisted; }; dictionary PageTransitionEventInit : EventInit { boolean persisted; }; interface BeforeUnloadEvent : Event { attribute DOMString returnValue; }; [NoInterfaceObject, Exposed=(Window, Worker)] interface NavigatorOnLine { readonly attribute boolean onLine; }; [Constructor(DOMString type, optional ErrorEventInit eventInitDict), Exposed=(Window, Worker)] interface ErrorEvent : Event { readonly attribute DOMString message; readonly attribute DOMString filename; readonly attribute unsigned long lineno; readonly attribute unsigned long colno; readonly attribute any error; }; dictionary ErrorEventInit : EventInit { DOMString message = ""; DOMString filename = ""; unsigned long lineno = 0; unsigned long colno = 0; any error = null; }; [Constructor(DOMString type, PromiseRejectionEventInit eventInitDict), Exposed=(Window,Worker)] interface PromiseRejectionEvent : Event { readonly attribute Promise<any> promise; readonly attribute any reason; }; dictionary PromiseRejectionEventInit : EventInit { required Promise<any> promise; any reason; }; [TreatNonObjectAsNull] callback EventHandlerNonNull = any (Event event); typedef EventHandlerNonNull? EventHandler; [TreatNonObjectAsNull] callback OnErrorEventHandlerNonNull = any ((Event or DOMString) event, optional DOMString source, optional unsigned long lineno, optional unsigned long column, optional any error); typedef OnErrorEventHandlerNonNull? OnErrorEventHandler; [TreatNonObjectAsNull] callback OnBeforeUnloadEventHandlerNonNull = DOMString? (Event event); typedef OnBeforeUnloadEventHandlerNonNull? OnBeforeUnloadEventHandler; [NoInterfaceObject] interface GlobalEventHandlers { attribute EventHandler onabort; attribute EventHandler onblur; attribute EventHandler oncancel; attribute EventHandler oncanplay; attribute EventHandler oncanplaythrough; attribute EventHandler onchange; attribute EventHandler onclick; attribute EventHandler onclose; attribute EventHandler oncontextmenu; attribute EventHandler oncuechange; attribute EventHandler ondblclick; attribute EventHandler ondrag; attribute EventHandler ondragend; attribute EventHandler ondragenter; attribute EventHandler ondragexit; attribute EventHandler ondragleave; attribute EventHandler ondragover; attribute EventHandler ondragstart; attribute EventHandler ondrop; attribute EventHandler ondurationchange; attribute EventHandler onemptied; attribute EventHandler onended; attribute OnErrorEventHandler onerror; attribute EventHandler onfocus; attribute EventHandler oninput; attribute EventHandler oninvalid; attribute EventHandler onkeydown; attribute EventHandler onkeypress; attribute EventHandler onkeyup; attribute EventHandler onload; attribute EventHandler onloadeddata; attribute EventHandler onloadedmetadata; attribute EventHandler onloadstart; attribute EventHandler onmousedown; [LenientThis] attribute EventHandler onmouseenter; [LenientThis] attribute EventHandler onmouseleave; attribute EventHandler onmousemove; attribute EventHandler onmouseout; attribute EventHandler onmouseover; attribute EventHandler onmouseup; attribute EventHandler onwheel; attribute EventHandler onpause; attribute EventHandler onplay; attribute EventHandler onplaying; attribute EventHandler onprogress; attribute EventHandler onratechange; attribute EventHandler onreset; attribute EventHandler onresize; attribute EventHandler onscroll; attribute EventHandler onseeked; attribute EventHandler onseeking; attribute EventHandler onselect; attribute EventHandler onshow; attribute EventHandler onstalled; attribute EventHandler onsubmit; attribute EventHandler onsuspend; attribute EventHandler ontimeupdate; attribute EventHandler ontoggle; attribute EventHandler onvolumechange; attribute EventHandler onwaiting; }; [NoInterfaceObject] interface WindowEventHandlers { attribute EventHandler onafterprint; attribute EventHandler onbeforeprint; attribute OnBeforeUnloadEventHandler onbeforeunload; attribute EventHandler onhashchange; attribute EventHandler onlanguagechange; attribute EventHandler onmessage; attribute EventHandler onoffline; attribute EventHandler ononline; attribute EventHandler onpagehide; attribute EventHandler onpageshow; attribute EventHandler onrejectionhandled; attribute EventHandler onpopstate; attribute EventHandler onstorage; attribute EventHandler onunhandledrejection; attribute EventHandler onunload; }; [NoInterfaceObject] interface DocumentAndElementEventHandlers { attribute EventHandler oncopy; attribute EventHandler oncut; attribute EventHandler onpaste; }; [NoInterfaceObject, Exposed=(Window, Worker)] interface WindowBase64 { DOMString btoa(DOMString btoa); DOMString atob(DOMString atob); }; Window implements WindowBase64; WorkerGlobalScope implements WindowBase64; [NoInterfaceObject, Exposed=(Window,Worker)] interface WindowTimers { long setTimeout((Function or DOMString) handler, optional long timeout = 0, any... arguments); void clearTimeout(optional long handle = 0); long setInterval((Function or DOMString) handler, optional long timeout = 0, any... arguments); void clearInterval(optional long handle = 0); }; Window implements WindowTimers; WorkerGlobalScope implements WindowTimers; [NoInterfaceObject] interface WindowModal { readonly attribute any dialogArguments; attribute any returnValue; }; interface Navigator { // objects implementing this interface also implement the interfaces given below }; Navigator implements NavigatorID; Navigator implements NavigatorLanguage; Navigator implements NavigatorOnLine; Navigator implements NavigatorContentUtils; Navigator implements NavigatorCookies; Navigator implements NavigatorPlugins; [NoInterfaceObject, Exposed=(Window, Worker)] interface NavigatorID { [Exposed=Window] readonly attribute DOMString appCodeName; // constant "Mozilla" readonly attribute DOMString appName; // constant "Netscape" readonly attribute DOMString appVersion; readonly attribute DOMString platform; [Exposed=Window]readonly attribute DOMString product; // constant "Gecko" readonly attribute DOMString userAgent; }; [NoInterfaceObject, Exposed=(Window, Worker)] interface NavigatorLanguage { readonly attribute DOMString? language; readonly attribute DOMString[] languages; }; [NoInterfaceObject] interface NavigatorContentUtils { // content handler registration void registerProtocolHandler(DOMString scheme, DOMString url, DOMString title); void unregisterProtocolHandler(DOMString scheme, DOMString url); }; [NoInterfaceObject] interface NavigatorCookies { readonly attribute boolean cookieEnabled; }; [NoInterfaceObject] interface NavigatorPlugins { [SameObject] readonly attribute PluginArray plugins; [SameObject] readonly attribute MimeTypeArray mimeTypes; boolean javaEnabled(); }; interface PluginArray { void refresh(optional boolean reload = false); readonly attribute unsigned long length; getter Plugin? item(unsigned long index); getter Plugin? namedItem(DOMString name); }; interface MimeTypeArray { readonly attribute unsigned long length; getter MimeType? item(unsigned long index); getter MimeType? namedItem(DOMString name); }; interface Plugin { readonly attribute DOMString name; readonly attribute DOMString description; readonly attribute DOMString filename; readonly attribute unsigned long length; getter MimeType? item(unsigned long index); getter MimeType? namedItem(DOMString name); }; interface MimeType { readonly attribute DOMString type; readonly attribute DOMString description; readonly attribute DOMString suffixes; // comma-separated readonly attribute Plugin enabledPlugin; }; [Exposed=(Window, Worker)] interface ImageBitmap { readonly attribute unsigned long width; readonly attribute unsigned long height; }; typedef (HTMLImageElement or HTMLVideoElement or HTMLCanvasElement or Blob or ImageData or CanvasRenderingContext2D or ImageBitmap) ImageBitmapSource; [NoInterfaceObject, Exposed=(Window, Worker)] interface ImageBitmapFactories { Promise<ImageBitmap> createImageBitmap(ImageBitmapSource image); Promise<ImageBitmap> createImageBitmap(ImageBitmapSource image, long sx, long sy, long sw, long sh); }; Window implements ImageBitmapFactories; WorkerGlobalScope implements ImageBitmapFactories; interface HTMLAppletElement : HTMLElement { attribute DOMString align; attribute DOMString alt; attribute DOMString archive; attribute DOMString code; attribute DOMString codeBase; attribute DOMString height; attribute unsigned long hspace; attribute DOMString name; attribute DOMString _object; // the underscore is not part of the identifier attribute unsigned long vspace; attribute DOMString width; }; interface HTMLMarqueeElement : HTMLElement { attribute DOMString behavior; attribute DOMString bgColor; attribute DOMString direction; attribute DOMString height; attribute unsigned long hspace; attribute long loop; attribute unsigned long scrollAmount; attribute unsigned long scrollDelay; attribute boolean trueSpeed; attribute unsigned long vspace; attribute DOMString width; attribute EventHandler onbounce; attribute EventHandler onfinish; attribute EventHandler onstart; void start(); void stop(); }; interface HTMLFrameSetElement : HTMLElement { attribute DOMString cols; attribute DOMString rows; }; HTMLFrameSetElement implements WindowEventHandlers; interface HTMLFrameElement : HTMLElement { attribute DOMString name; attribute DOMString scrolling; attribute DOMString src; attribute DOMString frameBorder; attribute boolean noResize; readonly attribute Document? contentDocument; readonly attribute WindowProxy? contentWindow; [TreatNullAs=EmptyString] attribute DOMString marginHeight; [TreatNullAs=EmptyString] attribute DOMString marginWidth; }; [Exposed=(Window, SharedWorker)] interface ApplicationCache : EventTarget { // update status const unsigned short UNCACHED = 0; const unsigned short IDLE = 1; const unsigned short CHECKING = 2; const unsigned short DOWNLOADING = 3; const unsigned short UPDATEREADY = 4; const unsigned short OBSOLETE = 5; readonly attribute unsigned short status; // updates void update(); void abort(); void swapCache(); // events attribute EventHandler onchecking; attribute EventHandler onerror; attribute EventHandler onnoupdate; attribute EventHandler ondownloading; attribute EventHandler onprogress; attribute EventHandler onupdateready; attribute EventHandler oncached; attribute EventHandler onobsolete; }; partial interface HTMLAnchorElement { attribute DOMString coords; attribute DOMString charset; attribute DOMString name; attribute DOMString shape; }; partial interface HTMLAreaElement { attribute boolean noHref; }; partial interface HTMLBodyElement { [TreatNullAs=EmptyString] attribute DOMString text; [TreatNullAs=EmptyString] attribute DOMString link; [TreatNullAs=EmptyString] attribute DOMString vLink; [TreatNullAs=EmptyString] attribute DOMString aLink; [TreatNullAs=EmptyString] attribute DOMString bgColor; attribute DOMString background; }; partial interface HTMLBRElement { attribute DOMString clear; }; partial interface HTMLTableCaptionElement { attribute DOMString align; }; partial interface HTMLTableColElement { attribute DOMString align; attribute DOMString ch; attribute DOMString chOff; attribute DOMString vAlign; attribute DOMString width; }; interface HTMLDirectoryElement : HTMLElement { attribute boolean compact; }; partial interface HTMLDivElement { attribute DOMString align; }; partial interface HTMLDListElement { attribute boolean compact; }; partial interface HTMLEmbedElement { attribute DOMString align; attribute DOMString name; }; interface HTMLFontElement : HTMLElement { [TreatNullAs=EmptyString] attribute DOMString color; attribute DOMString face; attribute DOMString size; }; partial interface HTMLHeadingElement { attribute DOMString align; }; partial interface HTMLHRElement { attribute DOMString align; attribute DOMString color; attribute boolean noShade; attribute DOMString size; attribute DOMString width; }; partial interface HTMLHtmlElement { attribute DOMString version; }; partial interface HTMLIFrameElement { attribute DOMString align; attribute DOMString scrolling; attribute DOMString frameBorder; [TreatNullAs=EmptyString] attribute DOMString marginHeight; [TreatNullAs=EmptyString] attribute DOMString marginWidth; }; partial interface HTMLImageElement { attribute DOMString name; attribute DOMString lowsrc; attribute DOMString align; attribute unsigned long hspace; attribute unsigned long vspace; [TreatNullAs=EmptyString] attribute DOMString border; }; partial interface HTMLInputElement { attribute DOMString align; attribute DOMString useMap; }; partial interface HTMLLegendElement { attribute DOMString align; }; partial interface HTMLLIElement { attribute DOMString type; }; partial interface HTMLLinkElement { attribute DOMString charset; attribute DOMString target; }; partial interface HTMLMenuElement { attribute boolean compact; }; partial interface HTMLMetaElement { attribute DOMString scheme; }; partial interface HTMLObjectElement { attribute DOMString align; attribute DOMString archive; attribute DOMString code; attribute boolean declare; attribute unsigned long hspace; attribute DOMString standby; attribute unsigned long vspace; attribute DOMString codeBase; attribute DOMString codeType; attribute DOMString useMap; [TreatNullAs=EmptyString] attribute DOMString border; }; partial interface HTMLOListElement { attribute boolean compact; }; partial interface HTMLParagraphElement { attribute DOMString align; }; partial interface HTMLParamElement { attribute DOMString type; attribute DOMString valueType; }; partial interface HTMLPreElement { attribute long width; }; partial interface HTMLScriptElement { attribute DOMString event; attribute DOMString htmlFor; }; partial interface HTMLTableElement { attribute DOMString align; attribute DOMString border; attribute DOMString frame; attribute DOMString rules; attribute DOMString summary; attribute DOMString width; [TreatNullAs=EmptyString] attribute DOMString bgColor; [TreatNullAs=EmptyString] attribute DOMString cellPadding; [TreatNullAs=EmptyString] attribute DOMString cellSpacing; }; partial interface HTMLTableSectionElement { attribute DOMString align; attribute DOMString ch; attribute DOMString chOff; attribute DOMString vAlign; }; partial interface HTMLTableCellElement { attribute DOMString align; attribute DOMString axis; attribute DOMString height; attribute DOMString width; attribute DOMString ch; attribute DOMString chOff; attribute boolean noWrap; attribute DOMString vAlign; [TreatNullAs=EmptyString] attribute DOMString bgColor; }; partial interface HTMLTableDataCellElement { attribute DOMString abbr; }; partial interface HTMLTableRowElement { attribute DOMString align; attribute DOMString ch; attribute DOMString chOff; attribute DOMString vAlign; [TreatNullAs=EmptyString] attribute DOMString bgColor; }; partial interface HTMLUListElement { attribute boolean compact; attribute DOMString type; }; partial interface Document { [TreatNullAs=EmptyString] attribute DOMString fgColor; [TreatNullAs=EmptyString] attribute DOMString linkColor; [TreatNullAs=EmptyString] attribute DOMString vlinkColor; [TreatNullAs=EmptyString] attribute DOMString alinkColor; [TreatNullAs=EmptyString] attribute DOMString bgColor; [SameObject] readonly attribute HTMLCollection anchors; [SameObject] readonly attribute HTMLCollection applets; void clear(); void captureEvents(); void releaseEvents(); [SameObject] readonly attribute HTMLAllCollection all; }; partial interface Window { void captureEvents(); void releaseEvents(); [Replaceable, SameObject] readonly attribute External external; }; [NoInterfaceObject] interface External { void AddSearchProvider(); void IsSearchProviderInstalled(); };
References
Normative References
- [ABNF]
- D. Crocker, Ed.; P. Overell. Augmented BNF for Syntax Specifications: ABNF. January 2008. Internet Standard. URL: https://tools.ietf.org/html/rfc5234
- [BCP47]
- A. Phillips; M. Davis. Tags for Identifying Languages. September 2009. IETF Best Current Practice. URL: https://tools.ietf.org/html/bcp47
- [BIDI]
- Mark Davis; Aharon Lanin; Andrew Glass. Unicode Bidirectional Algorithm. 5 June 2014. Unicode Standard Annex #9. URL: http://www.unicode.org/reports/tr9/
- [CANVAS-2D]
- Rik Cabanier; et al. HTML Canvas 2D Context. 19 November 2015. REC. URL: https://www.w3.org/TR/2dcontext/
- [CLDR]
- Unicode Common Locale Data Repository. URL: http://cldr.unicode.org/
- A. Barth. HTTP State Management Mechanism. April 2011. Proposed Standard. URL: https://tools.ietf.org/html/rfc6265
- [CSP3]
- Mike West. Content Security Policy Level 3. 1 September 2016. WD. URL: https://www.w3.org/TR/CSP3/
- [CSS-2015]
- Tab Atkins Jr.; Elika Etemad; Florian Rivoal. CSS Snapshot 2015. 13 October 2015. NOTE. URL: https://www.w3.org/TR/css-2015/
- [CSS-COLOR-4]
- Tab Atkins Jr.; Chris Lilley. CSS Color Module Level 4. 5 July 2016. WD. URL: https://www.w3.org/TR/css-color-4/
- [CSS-DISPLAY-3]
- Tab Atkins Jr.; Elika Etemad. CSS Display Module Level 3. 15 October 2015. WD. URL: https://www.w3.org/TR/css-display-3/
- [CSS-FONT-LOADING-3]
- Tab Atkins Jr.. CSS Font Loading Module Level 3. 22 May 2014. LCWD. URL: https://www.w3.org/TR/css-font-loading-3/
- [CSS-FONTS-3]
- John Daggett. CSS Fonts Module Level 3. 3 October 2013. CR. URL: https://www.w3.org/TR/css-fonts-3/
- [CSS-OVERFLOW-3]
- David Baron; Florian Rivoal. CSS Overflow Module Level 3. 31 May 2016. WD. URL: https://www.w3.org/TR/css-overflow-3/
- [CSS-SIZING-3]
- Tab Atkins Jr.; Elika Etemad. CSS Intrinsic & Extrinsic Sizing Module Level 3. 12 May 2016. WD. URL: https://www.w3.org/TR/css-sizing-3/
- [CSS-STYLE-ATTR]
- Tantek Çelik; Elika Etemad. CSS Style Attributes. 7 November 2013. REC. URL: https://www.w3.org/TR/css-style-attr
- [CSS-SYNTAX-3]
- Tab Atkins Jr.; Simon Sapin. CSS Syntax Module Level 3. 20 February 2014. CR. URL: https://www.w3.org/TR/css-syntax-3/
- [CSS-TEXT-3]
- Elika Etemad; Koji Ishii. CSS Text Module Level 3. 10 October 2013. LCWD. URL: https://www.w3.org/TR/css-text-3/
- [CSS-TRANSITIONS-1]
- CSS Transitions Module Level 1 URL: https://www.w3.org/TR/css3-transitions/
- [CSS-UI-3]
- Tantek Çelik; Florian Rivoal. CSS Basic User Interface Module Level 3 (CSS3 UI). 7 July 2015. CR. URL: https://www.w3.org/TR/css-ui-3/
- [CSS-UI-4]
- Florian Rivoal. CSS Basic User Interface Module Level 4. 22 September 2015. WD. URL: https://www.w3.org/TR/css-ui-4/
- [CSS-VALUES]
- Tab Atkins Jr.; Elika Etemad. CSS Values and Units Module Level 3. 11 June 2015. CR. URL: https://www.w3.org/TR/css-values/
- [CSS-WRITING-MODES-3]
- Elika Etemad; Koji Ishii. CSS Writing Modes Level 3. 15 December 2015. CR. URL: https://www.w3.org/TR/css-writing-modes-3/
- [CSS2]
- Bert Bos; et al. Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification. 7 June 2011. REC. URL: https://www.w3.org/TR/CSS2
- [CSS22]
- Bert Bos. Cascading Style Sheets Level 2 Revision 2 (CSS 2.2) Specification. 12 April 2016. WD. URL: https://www.w3.org/TR/CSS22/
- [CSS3-CONTENT]
- Elika Etemad; Dave Cramer. CSS Generated Content Module Level 3. 2 June 2016. WD. URL: https://www.w3.org/TR/css-content-3/
- [CSS3-IMAGES]
- Elika Etemad; Tab Atkins Jr.. CSS Image Values and Replaced Content Module Level 3. 17 April 2012. CR. URL: https://www.w3.org/TR/css3-images/
- [CSS3-RUBY]
- Elika Etemad; Koji Ishii. CSS Ruby Layout Module Level 1. 5 August 2014. WD. URL: https://www.w3.org/TR/css-ruby-1/
- [CSS3-SELECTORS]
- Tantek Çelik; et al. Selectors Level 3. 29 September 2011. REC. URL: https://www.w3.org/TR/css3-selectors/
- [CSS3COLOR]
- Tantek Çelik; Chris Lilley; David Baron. CSS Color Module Level 3. 7 June 2011. REC. URL: https://www.w3.org/TR/css3-color
- [CSSOM]
- Simon Pieters; Glenn Adams. CSS Object Model (CSSOM). 17 March 2016. WD. URL: https://www.w3.org/TR/cssom-1/
- [CSSOM-VIEW]
- Simon Pieters. CSSOM View Module. 17 March 2016. WD. URL: https://www.w3.org/TR/cssom-view-1/
- [DOM]
- Anne van Kesteren; et al. W3C DOM4. 19 November 2015. REC. URL: https://www.w3.org/TR/dom/
- [DOM-Parsing]
- Travis Leithead. DOM Parsing and Serialization. 17 May 2016. WD. URL: https://www.w3.org/TR/DOM-Parsing/
- [ECMA-262]
- ECMAScript Language Specification. URL: https://tc39.github.io/ecma262/
- [ENCODING]
- Anne van Kesteren; Joshua Bell; Addison Phillips. Encoding. 20 October 2015. CR. URL: https://www.w3.org/TR/encoding/
- [EVENTSOURCE]
- Ian Hickson. Server-Sent Events. 3 February 2015. REC. URL: https://www.w3.org/TR/eventsource/
- [FETCH]
- Anne van Kesteren. Fetch Standard. Continually Updated Specification. URL: https://fetch.spec.whatwg.org/
- [FILEAPI]
- Arun Ranganathan; Jonas Sicking. File API. 21 April 2015. WD. URL: https://www.w3.org/TR/FileAPI/
- [FULLSCREEN]
- Anne van Kesteren; Tantek Çelik. Fullscreen. 18 November 2014. NOTE. URL: https://www.w3.org/TR/fullscreen/
- [GEOMETRY-1]
- Simon Pieters; Dirk Schulze; Rik Cabanier. Geometry Interfaces Module Level 1. 25 November 2014. CR. URL: https://www.w3.org/TR/geometry-1/
- [HR-TIME-2]
- Ilya Grigorik; James Simonsen; Jatinder Mann. High Resolution Time Level 2. 20 July 2016. WD. URL: https://www.w3.org/TR/hr-time-2/
- [HTML-AAM-1.0]
- Steve Faulkner; et al. HTML Accessibility API Mappings 1.0. 3 December 2015. WD. URL: https://www.w3.org/TR/html-aam-1.0/
- [HTML-ARIA]
- Steve Faulkner. ARIA in HTML. 2 September 2016. WD. URL: https://www.w3.org/TR/html-aria/
- [HTTP]
-
HTTP is the union of a set of RFCs:
- Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing (URL: https://tools.ietf.org/html/rfc7230), R. Fielding, J. Reschke. IETF.
- Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content (URL: https://tools.ietf.org/html/rfc7231), R. Fielding, J. Reschke. IETF.
- Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests (URL: https://tools.ietf.org/html/rfc7232), R. Fielding, J. Reschke. IETF.
- Hypertext Transfer Protocol (HTTP/1.1): Range Requests (URL: https://tools.ietf.org/html/rfc7233), R. Fielding, Y. Lafon, J. Reschke. IETF.
- Hypertext Transfer Protocol (HTTP/1.1): Caching (URL: https://tools.ietf.org/html/rfc7234), R. Fielding, M. Nottingham, J. Reschke. IETF.
- Hypertext Transfer Protocol (HTTP/1.1): Authentication (URL: https://tools.ietf.org/html/rfc7235), R. Fielding, J. Reschke. IETF.
- [IANAPERMHEADERS]
- Permanent Message Header Field Names. IANA.
- [ISO3166]
- ISO 3166: Codes for the representation of names of countries and their subdivisions. ISO.
- [ISO4217]
- ISO 4217: Codes for the representation of currencies and funds. ISO.
- [JPEG]
- Eric Hamilton. JPEG File Interchange Format. September 1992. URL: https://www.w3.org/Graphics/JPEG/jfif3.pdf
- [MATHML]
- Patrick D F Ion; Robert R Miner. Mathematical Markup Language (MathML) 1.01 Specification. 7 July 1999. REC. URL: https://www.w3.org/TR/MathML/
- [MEDIA-FRAGS]
- Raphaël Troncy; et al. Media Fragments URI 1.0 (basic). 25 September 2012. REC. URL: https://www.w3.org/TR/media-frags/
- [MEDIA-SOURCE]
- Matthew Wolenetz; et al. Media Source Extensions. 5 July 2016. CR. URL: https://www.w3.org/TR/media-source/
- [MEDIACAPTURE-STREAMS]
- Daniel Burnett; et al. Media Capture and Streams. 19 May 2016. CR. URL: https://www.w3.org/TR/mediacapture-streams/
- [MEDIAQ]
- Florian Rivoal; et al. Media Queries. 19 June 2012. REC. URL: https://www.w3.org/TR/css3-mediaqueries/
- [MEDIAQUERIES-4]
- Florian Rivoal; Tab Atkins Jr.. Media Queries Level 4. 6 July 2016. WD. URL: https://www.w3.org/TR/mediaqueries-4/
- [MFREL]
- Microformats Wiki: existing rel values. Microformats.
- [MIMESNIFF]
-
As of today the Web community lacks a sufficiently complete, reliable, interoperable, and tested specification for the manner in which content sniffing takes place on the Web. We encourage implementers to exercise caution in this area as the Web community makes progress towards addressing this issue.
Gordon P. Hemsley. MIME Sniffing Standard. Continually Updated Specification. URL: https://mimesniff.spec.whatwg.org/
- [MPEG2TS]
- Information technology -- Generic coding of moving pictures and associated audio information: Systems ITU-T Rec. H.222.0 / ISO/IEC 13818-1:2013. URL: http://www.itu.int/rec/T-REC-H.222.0-201206-I
- [MPEG4]
- ISO/IEC 14496-12: ISO base media file format. ISO/IEC.
- [MPEGDASH]
- ISO/IEC 23009-1:2014 Information technology -- Dynamic adaptive streaming over HTTP (DASH) -- Part 1: Media presentation description and segment formats. URL: http://standards.iso.org/ittf/PubliclyAvailableStandards/c065274_ISO_IEC_23009-1_2014.zip
- [OGGSKELETON]
- Ogg Skeleton 4 Message Headers. 17 March 2014. URL: http://wiki.xiph.org/SkeletonHeaders
- [ORIGIN]
- A. Barth. The Web Origin Concept. December 2011. Proposed Standard. URL: https://tools.ietf.org/html/rfc6454
- [PAGE-VISIBILITY]
- Jatinder Mann; Arvind Jain. Page Visibility (Second Edition). 29 October 2013. REC. URL: https://www.w3.org/TR/page-visibility/
- [PNG]
- Tom Lane. Portable Network Graphics (PNG) Specification (Second Edition). 10 November 2003. REC. URL: https://www.w3.org/TR/PNG
- [POINTERLOCK]
- Vincent Scheib. Pointer Lock. 30 August 2016. PR. URL: https://www.w3.org/TR/pointerlock/
- [PROGRESS-EVENTS]
- Anne van Kesteren; Charles McCathie Nevile; Jungkee Song. Progress Events. 11 February 2014. REC. URL: https://www.w3.org/TR/progress-events/
- [PROMISES-GUIDE]
- Domenic Denicola. Writing Promise-Using Specifications. 16 February 2016. Finding of the W3C TAG. URL: https://www.w3.org/2001/tag/doc/promises-guide
- [PSL]
- Public Suffix List. Mozilla Foundation.
- [RESOURCE-HINTS]
- Ilya Grigorik. Resource Hints. 27 May 2016. WD. URL: https://www.w3.org/TR/resource-hints/
- [RFC1034]
- P.V. Mockapetris. Domain names - concepts and facilities. November 1987. Internet Standard. URL: https://tools.ietf.org/html/rfc1034
- [RFC1123]
- R. Braden, Ed.. Requirements for Internet Hosts - Application and Support. October 1989. Internet Standard. URL: https://tools.ietf.org/html/rfc1123
- [RFC2046]
- N. Freed; N. Borenstein. Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types. November 1996. Draft Standard. URL: https://tools.ietf.org/html/rfc2046
- [RFC2119]
- S. Bradner. Key words for use in RFCs to Indicate Requirement Levels. March 1997. Best Current Practice. URL: https://tools.ietf.org/html/rfc2119
- [RFC2318]
- H. Lie; B. Bos; C. Lilley. The text/css Media Type. March 1998. Informational. URL: https://tools.ietf.org/html/rfc2318
- [RFC2397]
- L. Masinter. The "data" URL scheme. August 1998. Proposed Standard. URL: https://tools.ietf.org/html/rfc2397
- [RFC2483]
- M. Mealling; R. Daniel. URI Resolution Services Necessary for URN Resolution. January 1999. Experimental. URL: https://tools.ietf.org/html/rfc2483
- [RFC3279]
- L. Bassham; W. Polk; R. Housley. Algorithms and Identifiers for the Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile. April 2002. Proposed Standard. URL: https://tools.ietf.org/html/rfc3279
- [RFC3447]
- J. Jonsson; B. Kaliski. Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1. February 2003. Informational. URL: https://tools.ietf.org/html/rfc3447
- [RFC4648]
- S. Josefsson. The Base16, Base32, and Base64 Data Encodings. October 2006. Proposed Standard. URL: https://tools.ietf.org/html/rfc4648
- [RFC5280]
- D. Cooper; et al. Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile. May 2008. Proposed Standard. URL: https://tools.ietf.org/html/rfc5280
- [RFC5322]
- P. Resnick, Ed.. Internet Message Format. October 2008. Draft Standard. URL: https://tools.ietf.org/html/rfc5322
- [RFC5724]
- E. Wilde; A. Vaha-Sipila. URI Scheme for Global System for Mobile Communications (GSM) Short Message Service (SMS). January 2010. Proposed Standard. URL: https://tools.ietf.org/html/rfc5724
- [RFC5988]
- M. Nottingham. Web Linking. October 2010. Proposed Standard. URL: https://tools.ietf.org/html/rfc5988
- [RFC6068]
- M. Duerst; L. Masinter; J. Zawinski. The 'mailto' URI Scheme. October 2010. Proposed Standard. URL: https://tools.ietf.org/html/rfc6068
- [RFC6266]
- J. Reschke. Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP). June 2011. Proposed Standard. URL: https://tools.ietf.org/html/rfc6266
- [RFC6381]
- R. Gellens; D. Singer; P. Frojdh. The 'Codecs' and 'Profiles' Parameters for "Bucket" Media Types. August 2011. Proposed Standard. URL: https://tools.ietf.org/html/rfc6381
- [RFC6455]
- I. Fette; A. Melnikov. The WebSocket Protocol. December 2011. Proposed Standard. URL: https://tools.ietf.org/html/rfc6455
- [RFC6694]
- S. Moonesamy, Ed.. The "about" URI Scheme. August 2012. Informational. URL: https://tools.ietf.org/html/rfc6694
- [RFC7230]
- R. Fielding, Ed.; J. Reschke, Ed.. Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing. June 2014. Proposed Standard. URL: https://tools.ietf.org/html/rfc7230
- [RFC7231]
- R. Fielding, Ed.; J. Reschke, Ed.. Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content. June 2014. Proposed Standard. URL: https://tools.ietf.org/html/rfc7231
- [RFC7232]
- R. Fielding, Ed.; J. Reschke, Ed.. Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests. June 2014. Proposed Standard. URL: https://tools.ietf.org/html/rfc7232
- [RFC7234]
- R. Fielding, Ed.; M. Nottingham, Ed.; J. Reschke, Ed.. Hypertext Transfer Protocol (HTTP/1.1): Caching. June 2014. Proposed Standard. URL: https://tools.ietf.org/html/rfc7234
- [RFC7303]
- H. Thompson; C. Lilley. XML Media Types. July 2014. Proposed Standard. URL: https://tools.ietf.org/html/rfc7303
- [RFC7578]
- L. Masinter. Returning Values from Forms: multipart/form-data. July 2015. Proposed Standard. URL: https://tools.ietf.org/html/rfc7578
- [RFC7595]
- D. Thaler, Ed.; T. Hansen; T. Hardie. Guidelines and Registration Procedures for URI Schemes. June 2015. Best Current Practice. URL: https://tools.ietf.org/html/rfc7595
- [SELECTION-API]
- Ryosuke Niwa. Selection API. 21 April 2016. WD. URL: https://www.w3.org/TR/selection-api/
- [SELECTORS-4]
- Selectors Level 4 URL: https://www.w3.org/TR/selectors4/
- [SERVICE-WORKERS]
- Alex Russell; Jungkee Song; Jake Archibald. Service Workers. 25 June 2015. WD. URL: https://www.w3.org/TR/service-workers/
- [SRGB]
- Amendment 1 - Multimedia systems and equipment - Colour measurement and management - Part 2-1: Colour management - Default RGB colour space - sRGB. URL: https://webstore.iec.ch/publication/6168
- [SVG]
- Jon Ferraiolo. Scalable Vector Graphics (SVG) 1.0 Specification. 4 September 2001. REC. URL: https://www.w3.org/TR/SVG/
- [SVG11]
- Erik Dahlström; et al. Scalable Vector Graphics (SVG) 1.1 (Second Edition). 16 August 2011. REC. URL: https://www.w3.org/TR/SVG11/
- [SVG2]
- Nikos Andronikos; et al. Scalable Vector Graphics (SVG) 2. 15 September 2015. WD. URL: https://www.w3.org/TR/SVG2/
- [SVGTiny12]
- Ola Andersson; et al. Scalable Vector Graphics (SVG) Tiny 1.2 Specification. 22 December 2008. REC. URL: https://www.w3.org/TR/SVGTiny12/
- [TOUCH-EVENTS]
- Doug Schepers; et al. Touch Events. 10 October 2013. REC. URL: https://www.w3.org/TR/touch-events/
- [UIEVENTS]
- Gary Kacmarcik; Travis Leithead. UI Events. 4 August 2016. WD. URL: https://www.w3.org/TR/uievents/
- [UNICODE]
- The Unicode Standard. URL: http://www.unicode.org/versions/latest/
- [URL]
-
Note: URLs can be used in numerous different manners, in many differing contexts. For the purpose of producing strict URLs one may wish to consider [RFC3986] [RFC3987]. The W3C URL specification defines the term URL, various algorithms for dealing with URLs, and an API for constructing, parsing, and resolving URLs. Developers of Web browsers are advised to keep abreast of the latest URL developments by tracking the progress of https://url.spec.whatwg.org/. We expect that the W3C URL draft will evolve along the Recommendation track as the community converges on a definition of URL processing.
Most of the URL-related terms used in the HTML specification (URL, absolute URL, relative URL, relative schemes, scheme component, scheme data, username, password, host, port, path, query, fragment, percent encode, get the base, and UTF-8 percent encode) can be straightforwardly mapped to the terminology of [RFC3986] [RFC3987]. The
URLUtils
(formerly known asURL
) collection of attributes (e.g.href
andprotocol
) and its required definitions (input, query encoding, url, update steps, set the input) are considered common practice nowadays. Some of the URL-related terms are still being refined (e.g. URL parser, parse errors, URL serializer, default encode set, and percent decode).As a word of caution, there are notable differences in the manner in which Web browsers and other software stacks outside the HTML context handle URLs. While no changes would be accepted to URL processing that would break existing Web content, some important parts of URL processing should therefore be considered as implementation-defined (e.g. parsing file: URLs or operating on URLs that would be syntax errors under the [RFC3986] [RFC3987] syntax).
Anne van Kesteren. URL Standard. Continually Updated Specification. URL: https://url.spec.whatwg.org/
- [URN]
- R. Moats. URN Syntax. May 1997. Proposed Standard. URL: https://tools.ietf.org/html/rfc2141
- [WAI-ARIA]
- James Craig; Michael Cooper; et al. Accessible Rich Internet Applications (WAI-ARIA) 1.0. 20 March 2014. REC. URL: https://www.w3.org/TR/wai-aria/
- [WEBGL]
- Chris Marrin (Apple Inc.). WebGL Specification, Version 1.0. 10 February 2011. URL: https://www.khronos.org/registry/webgl/specs/1.0/
- [WEBIDL]
- Cameron McCormack; Boris Zbarsky. WebIDL Level 1. 8 March 2016. CR. URL: https://www.w3.org/TR/WebIDL-1/
- [WEBM]
- WebM Container Guidelines. 26 April 2016. URL: https://www.webmproject.org/docs/container/
- [WEBSTORAGE]
- Ian Hickson. Web Storage (Second Edition). 19 April 2016. REC. URL: https://www.w3.org/TR/webstorage/
- [WEBWORKERS]
- Ian Hickson. Web Workers. 24 September 2015. WD. URL: https://www.w3.org/TR/workers/
- [X690]
- Recommendation X.690 — Information Technology — ASN.1 Encoding Rules — Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER), and Distinguished Encoding Rules (DER). International Telecommunication Union.
- [XML]
- Tim Bray; et al. Extensible Markup Language (XML) 1.0 (Fifth Edition). 26 November 2008. REC. URL: https://www.w3.org/TR/xml
- [XML-NAMES]
- Tim Bray; et al. Namespaces in XML 1.0 (Third Edition). 8 December 2009. REC. URL: https://www.w3.org/TR/xml-names
- [XML-STYLESHEET]
- James Clark; Simon Pieters; Henry Thompson. Associating Style Sheets with XML documents 1.0 (Second Edition). 28 October 2010. REC. URL: https://www.w3.org/TR/xml-stylesheet
- [XMLBASE]
- Jonathan Marsh. XML Base (Second Edition). 28 January 2009. REC. URL: https://www.w3.org/TR/xmlbase/
- [XPATH]
- James Clark; Steven DeRose. XML Path Language (XPath) Version 1.0. 16 November 1999. REC. URL: https://www.w3.org/TR/xpath
- [XPTR-XMLNS]
- Steven DeRose; et al. XPointer xmlns() Scheme. 25 March 2003. REC. URL: https://www.w3.org/TR/xptr-xmlns/
Informative References
- [APNG]
- S. Parmenter; V. Vukicevic; A. Smith. APNG Specification. URL: https://wiki.mozilla.org/APNG_Specification
- [ATAG20]
- Jan Richards; Jeanne F Spellman; Jutta Treviranus. Authoring Tool Accessibility Guidelines (ATAG) 2.0. 24 September 2015. REC. URL: https://www.w3.org/TR/ATAG20/
- [BATTERY-STATUS]
- Anssi Kostiainen; Mounir Lamouri. Battery Status API. 7 July 2016. CR. URL: https://www.w3.org/TR/battery-status/
- [BOCU1]
- M. Scherer; M. Davis. UTN #6: BOCU-1: MIME-Compatible Unicode Compression. URL: http://www.unicode.org/notes/tn6/
- [CESU8]
- T. Phipps. UTR #26: Compatibility Encoding Scheme For UTF-16: 8-BIT (CESU-8). URL: http://www.unicode.org/reports/tr26/
- [CHARMOD]
- Martin Dürst; et al. Character Model for the World Wide Web 1.0: Fundamentals. 15 February 2005. REC. URL: https://www.w3.org/TR/charmod/
- [COMPUTABLE]
- A. Turing. On computable numbers, with an application to the Entscheidungsproblem, Proceedings of the London Mathematical Society, series 2, volume 42,. 1937. URL: http://www.turingarchive.org/browse.php/B/12
- [CSS-CASCADE-3]
- Elika Etemad; Tab Atkins Jr.. CSS Cascading and Inheritance Level 3. 19 May 2016. CR. URL: https://www.w3.org/TR/css-cascade-3/
- [CSS-IMAGES-4]
- CSS Image Values and Replaced Content Module Level 4 URL: https://www.w3.org/TR/css4-images/
- [CSS-LISTS-3]
- Tab Atkins Jr.. CSS Lists and Counters Module Level 3. 20 March 2014. WD. URL: https://www.w3.org/TR/css-lists-3/
- [CSS3-ANIMATIONS]
- Dean Jackson; et al. CSS Animations. 19 February 2013. WD. URL: https://www.w3.org/TR/css3-animations/
- [CSS3-TRANSITIONS]
- Dean Jackson; et al. CSS Transitions. 19 November 2013. WD. URL: https://www.w3.org/TR/css3-transitions/
- [DOT]
- The DOT Language. URL: http://www.graphviz.org/content/dot-language
- [EDITING]
- A. Gregor. HTML Editing APIs. URL: https://dvcs.w3.org/hg/editing/raw-file/tip/editing.html
- [GIF]
- Graphics Interchange Format. 31 July 1990. URL: https://www.w3.org/Graphics/GIF/spec-gif89a.txt
- [GRAPHICS]
- Computer Graphics: Principles and Practice in C, Second Edition, J. Foley, A. van Dam, S. Feiner, J. Hughes. Addison-Wesley. ISBN 0-201-84840-6.
- [GREGORIAN]
- Inter Gravissimas, A. Lilius, C. Clavius. Gregory XIII Papal Bull, February 1582.
- [HTML-POLYGLOT]
- Eliot Graff; Leif Halvard Silli. Polyglot Markup: A robust profile of the HTML5 vocabulary. 29 September 2015. NOTE. URL: https://www.w3.org/TR/html-polyglot/
- [HTML5-DIFF]
- Simon Pieters. HTML5 Differences from HTML4. 9 December 2014. NOTE. URL: https://www.w3.org/TR/html5-diff/
- [INBANDTRACKS]
- Sourcing In-band Media Resource Tracks from Media Containers into HTML (URL: http://dev.w3.org/html5/html-sourcing-inband-tracks/), S. Pfeiffer, B. Lund. W3C.
- [IndexedDB]
- Nikunj Mehta; et al. Indexed Database API. 8 January 2015. REC. URL: https://www.w3.org/TR/IndexedDB/
- [ISO8601]
- Representation of dates and times. International Organization for Standardization. 2004. ISO 8601:2004. URL: http://www.iso.org/iso/catalogue_detail?csnumber=40874
- [JLREQ]
- Yasuhiro Anan; et al. Requirements for Japanese Text Layout. 3 April 2012. NOTE. URL: https://www.w3.org/TR/jlreq/
- [MNG]
- MNG (Multiple-image Network Graphics) Format. G. Randers-Pehrson.
- [NPAPI]
- Gecko Plugin API Reference. Mozilla.
- [OPENSEARCH]
- Autodiscovery in HTML/XHTML. In OpenSearch 1.1 Draft 4, Section 4.6.2. OpenSearch.org.
- [PDF]
- Document management — Portable document format — Part 1: PDF. ISO.
- [PPUTF8]
- The Properties and Promises of UTF-8, M. Dürst. University of Zürich. In Proceedings of the 11th International Unicode Conference.
- [RFC2152]
- D. Goldsmith; M. Davis. UTF-7 A Mail-Safe Transformation Format of Unicode. May 1997. Informational. URL: https://tools.ietf.org/html/rfc2152
- [RFC3676]
- R. Gellens. The Text/Plain Format and DelSp Parameters. February 2004. Proposed Standard. URL: https://tools.ietf.org/html/rfc3676
- [RFC4287]
- M. Nottingham, Ed.; R. Sayre, Ed.. The Atom Syndication Format. December 2005. Proposed Standard. URL: https://tools.ietf.org/html/rfc4287
- [RFC4329]
- B. Hoehrmann. Scripting Media Types. April 2006. Informational. URL: https://tools.ietf.org/html/rfc4329
- [RUBY-UC]
- Richard Ishida. Use Cases & Exploratory Approaches for Ruby Markup. 8 October 2013. NOTE. URL: https://www.w3.org/TR/ruby-use-cases/
- [SCSU]
- UTR #6: A Standard Compression Scheme For Unicode, M. Wolf, K. Whistler, C. Wicksteed, M. Davis, A. Freytag, M. Scherer. Unicode Consortium.
- [TIMEZONE]
- Addison Phillips; et al. Working with Time Zones. 5 July 2011. NOTE. URL: https://www.w3.org/TR/timezone
- [TOR]
- Tor.
- [TZDATABASE]
- Time Zone Database. IANA.
- [UAAG20]
- James Allan; et al. User Agent Accessibility Guidelines (UAAG) 2.0. 15 December 2015. NOTE. URL: https://www.w3.org/TR/UAAG20/
- [UNDO]
- Ryosuke Niwa. UndoManager and DOM Transaction. ED. URL: https://dvcs.w3.org/hg/undomanager/raw-file/tip/undomanager.html
- [UNICODE-SECURITY]
- Mark Davis; Michel Suignard. Unicode Security Considerations. URL: http://www.unicode.org/reports/tr36/
- [UNIVCHARDET]
- A composite approach to language/encoding detection, S. Li, K. Momoi. Netscape. In Proceedings of the 19th International Unicode Conference.
- [UTF8DET]
- Multilingual form encoding, M. Dürst. W3C.
- [WAI-ARIA-1.1]
- Joanmarie Diggs; et al. Accessible Rich Internet Applications (WAI-ARIA) 1.1. 21 July 2016. WD. URL: https://www.w3.org/TR/wai-aria-1.1/
- [WCAG20]
- Ben Caldwell; et al. Web Content Accessibility Guidelines (WCAG) 2.0. 11 December 2008. REC. URL: https://www.w3.org/TR/WCAG20/
- [WEBVTT]
- Simon Pieters. WebVTT: The Web Video Text Tracks Format. 8 December 2015. WD. URL: https://www.w3.org/TR/webvtt1/
- [WHATWGWIKI]
- The WHATWG Wiki. WHATWG.
- [XHR]
- Anne van Kesteren. XMLHttpRequest Standard. Continually Updated Specification. URL: https://xhr.spec.whatwg.org/
- [XML-ENTITY-NAMES]
- David Carlisle; Patrick D F Ion. XML Entity Definitions for Characters (2nd Edition). 10 April 2014. REC. URL: https://www.w3.org/TR/xml-entity-names/
- [XSLT]
- James Clark. XSL Transformations (XSLT) Version 1.0. 16 November 1999. REC. URL: https://www.w3.org/TR/xslt
Changes
This section summarises substantial substantive changes between Public Working Drafts, as a guide for general review.
Full details of all changes since 12 January 2016 are available from the commit log of the w3c/html github repository, including various editorial and linking fixes.
Changes since the 21 June 2016 Candidate Recommendation.
The following features, that were marked "at risk" were removed for lack of implementation:
- The
dialog
element - The
registerContentHandler()
,isContentHandlerRegistered()
andisProtocolHandlerRegistered()
methods - The
datetime
value for thetype
attribute of theinput
element - unimplemented parts of the autofill mechanism
- The
label
element is no longer Reassociatable - the
toolbar
type for themenu
element - the
inputmode
attribute
The mention of longdesc
at several places within the document was removed, since it is a separate W3C Recommendation
Changes between the 21 June 2016 Candidate Recommendation and the 3 May 2016 Public Working Draft.
- Changes to match implementation or reflect lack of it
- Add
oncopy
/oncut
/onpaste
handling- Remove
usemap
attribute onobject
- Remove
requestAutoComplete
- HTML Fragment serialisation doesn’t throw
- Allow
header
andfooter
elements to be nested if each level is within a sectioning element- Make the algorithm for forming a table closer to what implementations do with them
- Remove
multiple
attribute oninput type="range"
- Remove IntersectionObservers
- Remove
canvasProxy
,setContext
fromcanvas
- Make behaviour for fractional step values in
stepUp
andstepDown
match reality- Allow empty
option
elementsmousewheel
is nowwheel
- Remove
appCache
- Remove
MediaController
andmediagroup
attribute- Change
menu
/type
attribute token frompopup
tocontext
- Restore the
rev
attribute, used by RDFa, and e.g. Schema.org- Remove the nested
section
h1
outline model- Removed
style scoped
- Remove
- Changes related to other specifications
- Use closed blob from File API
- Integrate Resource Hints
- Update
HTMLAllCollection
to match Web IDL- Integrate the encoding specification
- Provide hooks to integrate CSP, and Realms from ECMAScript
- Integrate Resource Hints
- Fixes for specification bugs
value
attribute ofinput type="submit"
is translatable- added
requestAnimationFrame
- Having
title
, or writing email to a friend is not sufficient to make animg
conformant if theimg
/alt
attribute is missing- Fix the content model for
time
- Add
HTMLMediaElement
/srcObject
- added
Changes since the 12 April 2016 Public Working Draft.
- Changes to match implementation or reflect lack of it
- Removed
seamless
attribute on iframe- Removed table sorting
- Clarify that respecting user preferences for track selection is valid
- Allow
figcaption
anywhere within afigure
(not just first or last)- Remove special handling of
isindex
in form submission - Removed table sorting
- Normative reference changes
- Move from WCAG 1.0 to WCAG 2.0
Changes between the 12 April 2016 Public Working Draft and the 10 March 2016 Public Working Draft.
accesskey
attribute only takes a single character- This is to match implementation in browsers better.
- Add a callout to detach a media object in the media element load algorithm
- This is to synchronise with MSE.
- Remove microdata
- There is a https://www.w3.org/TR/2013/NOTE-microdata-20131029/W3C Note describing Microdata as an extension.
- Note that the attributes may be added back, referring to a Recommendation-track version of the extension, since there is a substantial amount of implementation.
Changes between the 10 March 2016 Public Working Draft and the 10 October 2015 Public Working Draft.
Full details of all changes since 12 January 2016 are available from the commit log of the w3c/html github repository. Note that a large number of changes made between 10 October and 12 January were copied direct from the whatwg/html repository.
- Removed because implementation is not consistent and the idea didn’t make sense
form
attribute onlabel
element.- Removed for lack of implementation and to potentially improve before re-adding
accessKeyLabel
IDL attribute.- Removed for lack of implementation
- Blank
alt
onarea
elements with duplicatehref
attributes is no longer conformant.- Browsers don’t know about the user’s keyboard
- Storage Mutex
navigator.yieldForStorageUpdates()
hreflang
andtype
attributes onarea
linksdocument.cssElementMap
andDOMElementMap
interfacedocument.commands
IDL- master commands concept in
menuitem
- Command API and related concepts
- Browsers don’t know about the user’s keyboard
- Focus navigation fixed
- When navigating internally, the next search for a link etc starts from where the navigation moved to - no longer optionally.
main
refers to thebody
- As opposed to be allowed multiple times in the page, for other elements
- More ways
p
can be automatigically closed- redefine "fully active" for a document
- Require that a document has its own browsing context to be fully active
- change currentSrc for images which don’t resolve
- From the absolute URL to the URL given to the resolver
a
is non-interactive if it has nohref
attribute- Fix Collections
HTMLFormControlsCollection
not used for collections offieldset
elements- Instead
fieldset
makes anHTMLCollection
namedItem
is an HTMLCollection not HTMLOptionsCollection- Instead
- Supported tokens
- Define supported tokens for link types and
dropzone
as those that have an impact on processing- add supported tokens for rel
- Allow more cross-origin…
- Enable cross-origin
track
andEventSource
- Allow cross-origin content for
ImageBitmap
incanvas
- let frameElement return null
- Allow cross-origin content for
- Transferable objects can go to different domains
- Make content of
time
consistent - Make content of
- There were contradictory requirements, now it is phrasing content, or text
- Integration with the ES job queue
- Defining EnqueueJob() and NextJob in a monkeypatch to ECMAScript.
- Add missing events
- Events and APIs for tracking promise rejection
event-source-error
error for media fetchingevent-track-error
andevent-track-load
- Make
navigator.javaEnabled()
a method- Table cleanups
- Add specific types for HTML table elements
.tFoot
an.createTFoot()
always insert at the end- Disallow
tfoot
beforetbody
- Clear autoplay flag once autoplaying
- Otherwise odd things happened if the network changed
- Cleaning up toBlob in
canvas
- Make the
toBlob()
callback non-nullable- Rename
fileCallback
toblobcallback
- Rename
- CSP hooks
- Add hooks for property on global object
- for inline events, styles
- inline elements
- update specification links
- for inline events, styles
- Flip modes (remote/local) in loading media resources
- make origin on HTMLHyperlinkElementUtils and Location readonly
meta refresh
parsing - make origin on HTMLHyperlinkElementUtils and Location readonly
- Match Gecko better
- make
;
optional - make
- Clean up SVG in HTML
- describe the flavour of SVG used in browsers
- Make SVG
title
first child not last - Make SVG
- Scroll restoration
- Add scroll restoration preferences to history traversal
- Clarify manual scrolling restoration
- Take account of
srclang
when renderingtrack
- Windows without browsing context
window.open()
can return null- Add "noopener" to
rel
andwindow
- Add "noopener" to
- Move HTTPS state from
window
todocument
- Drop some IDL attributes
[Exposed=Window]
for HTMLHyperLinkElementUtils[Exposed=Window, Worker]
for DOMStringMap- IDL Date
- Add IDL
[SameObject]
for some objects that return collections- Make script IDL attributes reflect
- Remove "no exception" step from HAVE_METADATA
- Fix mismatched HTMLMediaElement currentTime exception
- Make script IDL attributes reflect
- If there is a current media controller it can still throw…
setInterval()
timers clear too- Cleanup Fullscreen
- rename
menu type="popup"
asmenu type="context"
- Support
width="0"
- Cleanup Fullscreen
- For
img
and related elements, but not table cells
A description of substantial changes between the HTML 5.0 Recommendation of 2014 and the HTML 5.1 draft as it was in August 2015 is available as part of a separate document, that is no longer maintained.
Acknowledgements
Thanks to Tim Berners-Lee for inventing HTML, without which none of this would exist, Dan Connolly, the many who worked to standardise HTML over the last couple of decades or so, and the many more who worked on ideas subsequently incorporated into HTML.
For inestimable work, and the drive to keep HTML up to date, particular thanks are due to Ian Hickson, and the other editors of the WHATWG: Anne van Kesteren, Domenic Denicola, Philip Jägenstedt, Simon Pieters.
Thanks to the participants of the Responsive Images Community Group and the WHATWG for helping to develop the picture
element, the srcset
attribute,
and the sizes
attribute. Special thanks to Bruce Lawson for originally suggesting,
Edward O’Connor and Ian Hickson for writing the original srcset specification, and Adrian Bateman
for providing the group with guidance. Contributions also from: David Newton, Ilya Grigorik,
John Schoenick, and Leon de Rijke.
With apologies to people who have undeservedly not been named, thanks to
Aankhen, Aaron Boodman, Aaron Leventhal, Adam Barth, Adam de Boor, Adam Hepton, Adam Klein, Adam Roben, Addison Phillips, Adele Peterson, Adrian Bateman, Adrian Roselli, Adrian Sutton, Agustín Fernández, Aharon (Vladimir) Lanin, Ajai Tirumali, Akatsuki Kitamura, Alan Plum, Alastair Campbell, Alejandro G. Castro, Alex Bishop, Alex Nicolaou, Alex Plescan, Alex Rousskov, Alexander Farkas, Alexander J. Vincent, Alexander Surkov, Alexandre Morgaut, Alexey Feldgendler, Алексей Проскуряков (Alexey Proskuryakov), Alexis Deveria, Alice Boxhall, Allan Clements, Ami Fischman, Amos Jeffries, Anders Carlsson, André E. Veltstra, Andrea Rendine, Andreas, Andreas Kling, Andrei Popescu, Andres Gomez, Andrew Barfield, Andrew Clover, Andrew Gove, Andrew Grieve, Andrew Oakley, Andrew Sidwell, Andrew Simons, Andrew Smith, Andrew W. Hagen, Andrey V. Lukyanov, Andry Rendy, Andy Earnshaw, Andy Heydon, Andy Palay, Anjana Vakil, Anna Belle Leiserson, Anthony Boyd, Anthony Bryan, Anthony Hickson, Anthony Ramine, Anthony Ricaud, Antonio Olmo Titos, Antti Koivisto, Arkadiusz Michalski, Arne Thomassen, Aron Spohr, Arphen Lin, Arron Eicholz, Arthur Stolyar, Arun Patole, Aryeh Gregor, Asbjørn Ulsberg, Ashley Gullen, Ashley Sheridan, Atsushi Takayama, Aurelien Levy, Ave Wrigley, Axel Dahmen, B Lingafelter, Bart Humphries, Ben Boyle, Ben Buchanan, Ben Godfrey, Ben Lerner, Ben Leslie, Ben Meadowcroft, Ben Millard, Benjamin Carl Wiley Sittler, Benjamin Hawkes-Lewis, Benoit Ren, Bert Bos, Bijan Parsia, Bil Corry, Bill Mason, Bill McCoy, Billy Wong, Bjartur Thorlacius, Björn Höhrmann, Blake Frantz, Bob Lund, Bob Owen, Bobby Holly, Boris Zbarsky, Brad Fults, Brad Neuberg, Brad Spencer, Brady Eidson, Brendan Eich, Brenton Simpson, Brett Wilson, Brett Zamir, Brian Blakely, Brian Campbell, Brian Korver, Brian Kuhn, Brian M. Dube, Brian Ryner, Brian Smith, Brian Wilson, Bryan Sullivan, Bruce Bailey, Bruce D’Arcus, Bruce Lawson, Bruce Miller, C. Williams, Cameron McCormack, Cameron Zemek, Cao Yipeng, Carlos Amengual, Carlos Gabriel Cardona, Carlos Perelló Marín, Casey Leask, Cătălin Mariș, Chaals McCathie Nevile, Chao Cai, 윤석찬 (Channy Yun), Charl van Niekerk, Charles Iliya Krempeaux, Charu Pandhi, Chris Apers, Chris Cressman, Chris Evans, Chris Morris, Chris Pearce, Chris Peterson, Chris Weber, Christian Biesinger, Christian Johansen, Christian Schmidt, Christoph Päper, Christophe Dumez, Christopher Aillon, Christopher Ferris, Chriswa, Clark Buehler, Cole Robison, Colin Fine, Collin Jackson, Corey Farwell, Corprew Reed, Craig Cockburn, Csaba Gabor, Csaba Marton, Cynthia Shelly, Dan Brickley, Dan Yoder, Daniel Barclay, Daniel Bratell, Daniel Brooks, Daniel Brumbaugh Keeney, Daniel Cheng, Daniel Davis, Daniel Glazman, Daniel Peng, Daniel Schattenkirchner, Daniel Spång, Daniel Steinberg, Daniel Trebbien, Danny Sullivan, Darin Adler, Darin Fisher, Darxus, Dave Camp, Dave Hodder, Dave Lampton, Dave Singer, Dave Townsend, David Baron, David Bloom, David Bruant, David Carlisle, David E. Cleary, David Egan Evans, David Fink, David Flanagan, David Gerard, David Håsäther, David Hyatt, David I. Lehn, David John Burrowes, David Kendal, David MacDonald, David Matja, David Remahl, David Smith, David Storey, David Vest, David Woolley, DeWitt Clinton, Dean Edridge, Dean Edwards, Debi Orton, Derek Featherstone, Devarshi Pant, Devdatta, Dimitri Glazkov, Dimitry Golubovsky, Dirk Pranke, Dirk Schulze, Dirkjan Ochtman, Divya Manian, Dmitry Titov, dolphinling, Dominic Mazzoni, Dominique Hazaël-Massieux, Don Brutzman, Doron Rosenberg, Doug Kramer, Doug Simpkinson, Drew Wilson, Dylan Barrell, Edmund Lai, Eduard Pascual, Eduardo Vela, Edward O’Connor, Edward Welbourne, Edward Z. Yang, Ehsan Akhgari, Eira Monstad, Eitan Adler, Eliot Graff, Elisabeth Robson, Elizabeth Castro, Elliott Regan, Elliott Sprehn, Elliotte Harold, Eric Carlson, Eric Casler, Eric Lawrence, Eric Rescorla, Eric Semling, Erik Arvidsson, Erik Rose, Evan Jacobs, Evan Martin, Evan Prodromou, Evan Stade, Evert, fantasai, Felix Sasaki, Francesco Schwarz, Francis Brosnan Blazquez, Franck "Shift" Quélain, François Remy, Frank Barchard, Frank Liberato, Frank Olivier, Fredrik Söderquist, 鵜飼文敏 (Fumitoshi Ukai), Futomi Hatano, Gavin Carothers, Gavin Kistner, Gareth Rees, Gary Kačmarčík, Garrett Smith, Geoff Richards, Geoffrey Garen, Sam Sneddon, Gez Lemon, George Lund, George Ornbo, Gianmarco Armellin, Giovanni Campagna, Giuseppe Pascale, Glenn Adams, Glenn Maynard, Graham Klyne, Greg Botten, Greg Houston, Greg Wilkins, Gregg Tavares, Gregory J. Rosmaita, Grey, Guilherme Johansson Tramontina, Gytis Jakutonis, Håkon Wium Lie, Habib Virji, Hallvord Reiar Michaelsen Steen, Hans S. Tømmerhalt, Hans Stimer, Harald Alvestrand, Henri Sivonen, Henrik Lied, Henry Mason, Henry Story, Heydon Pickering, Hugh Guiney, Hugh Winkler, Ian Bicking, Ian Clelland, Ian Davis, Ian Devlin, Ian Fette, Ian Kilpatrick, Ido Green, Ignacio Javier, Ivan Enderlin, Ivo Emanuel Gonçalves, J. King, Jacob Davies, Jacques Distler, Jake Verbaten, Jakub Łopuszański, Jakub Wilk, James Craig, James Graham, James Greene, James Justin Harrell, James Kozianski, James M Snell, James Perrett, James Robinson, Jamie Lokier, Jan Molnár, Janusz Majnert, Jan-Klaas Kollhof, Jared Jacobs, Jason Duell, Jason Kersey, Jason Kiss, Jason Lustig, Jason White, Jasper Bryant-Greene, Jasper St. Pierre, Jatinder Mann, Jdsmith3000, Jed Hartman, Jeff Balogh, Jeff Cutsinger, Jeff Schiller, Jeff Walden, Jeffrey Yasskin, Jeffrey Zeldman, 胡慧鋒 (Jennifer Braithwaite), Jens Bannmann, Jens Fendler, Jens Lindström, Jens Meiert, Jer Noble, Jeremey Hustman, Jeremy Keith, Jeremy Orlow, Jerry Smith, Jeroen van der Meer, Jesse Renée Beach, Jian Li, Jim Jewett, Jim Ley, Jim Meehan, Jim Michaels, Jirka Kosek, Jjgod Jiang, João Eiras, Jochen Eisinger, Joe Clark, Joe Gregorio, Joel Spolsky, Joel Verhagen, Johan Herland, John Boyer, John Bussjaeger, John Carpenter, John Daggett, John Fallows, John Foliot, John Harding, John Keiser, John Snyders, John Stockton, John-Mark Bell, Johnny Stenback, Jon Ferraiolo, Jon Gibbins, Jon Gunderson, Jon Ribbins, Jon Perlow, Jonas Sicking, Jonathan Cook, Jonathan Kingston, Jonathan Rees, Jonathan Watt, Jonathan Worent, Jonny Axelsson, Jordan Tucker, Jorgen Horstink, Jorunn Danielsen Newth, Joseph Kesselman, Joseph Mansfield, Joseph Pecoraro, Josh Aas, Josh Hart, Josh Levenberg, Josh Matthews, Joshua Bell, Joshua Berenhaus, Joshua Randall, Jukka K. Korpela, Jules Clément-Ripoche, Julian Reschke, Julio Lopez, Junkee Song, Jürgen Jeka, Justin Lebar, Justin Novosad, Justin Rogers, Justin Schuh, Justin Sinclair, Ka-Sing Chou, Kai Hendry, 呂康豪 (KangHao Lu), Karl Dubost, Karl Groves, Kartikaya Gupta, Kathy Walton, Keith Hall, Keith Yeung, Kelly Ford, Kelly Norton, Kevin Benson, Kevin Gadd, Kevin Cole, Kinuko Yasuda Kornél Pál, Kornel Lesinski, Kris Northfield, Kristof Zelechovski, Krzysztof Maczyński, 黒澤剛志 (Kurosawa Takeshi), Kyle Barnhart, Kyle Hofmann, Kyle Huey, Léonard Bouchet, Lachlan Hunt, Larry Masinter, Larry Page, Lars Gunther, Lars Solberg, Laura Carlson, Laura Granka, Laura L. Carlson, Laura Wisewell, Laurens Holst, Lawrence Forooghian, Lea Verou, Lee Kowalkowski, Leif Halvard Silli, Leif Kornstaedt, Lenny Domnitser, Leonard Rosenthol, Léonie Watson, Leons Petrazickis, Lobotom Dysmon, Logan, Loune, Łukasz Pilorz, Luke Kenneth Casson Leighton, Maciej Stachowiak, Magnus Kristiansen, Maik Merten, Majid Valipour, Malcolm Rowe, Manu Sporny, Manuel Strehl, Manish Tripathi, Mallory van Achterberg, Marat Talanin, Marc Hoyois, Marcus Bointon, Mark Birbeck, Mark Davis, Mark Miller, Mark Nottingham, Mark Pilgrim, Mark Rogers, Mark Rowe, Mark Schenk, Mark Vickers, Mark Wilton-Jones, Marquish, Martijn Wargers, Martin Atkins, Martin Dürst, Martin Honnen, Martin Janecke, Martin Kutschker, Martin Nilsson, Martin Thomson, Masataka Yakura, Masatoshi Kimura, Matheus Martins, Mathias Bynens, Mathieu Henri, Matias Larsson, Matt Falkenhagen, Matt Garrish, Matt May, Matt Rakow, Matt Schmidt, Matt Wright, Matthew Gregan, Matthew Mastracci, Matthew Noorenberghe, Matthew Raymond, Matthew Thomas, Mattias Waldau, Max Romantschuk, Menachem Salomon, Menno van Slooten, Mia Lipner, Micah Dubinko, Michael "Ratt" Iannarelli, Michael A. Nachbaur, Michael A. Puls II, Michael Carter, Michael Daskalov, Michael Day, Michael Dyck, Michael Enright, Michael Gratton, Michael Nordman, Michael Powers, Michael Rakowski, Michael(tm) Smith, Michael Walmsley, Michal Zalewski, Michel Fortin, Michelangelo De Simone, Zoë Bijl, Michiel van der Blonk, Mihai Şucan, Mihai Parparita, Mike Brown, Mike Dierken, Mike Dixon, Mike Hearn, Mike Schinkel, Mike Shaver, Mikko Rantalainen, Mohamed Zergaoui, Mohammad Al Houssami, Momdo Nakamura, Mounir Lamouri, Mount-root-yy, Ms2ger, Nadia Heninger, Nhan, NARUSE Yui, Neil Deakin, Neil Rashbrook, Neil Soiffer, Nicholas Shanks, Nicholas Stimpson, Nicholas Zakas, Nick Levinson, Nickolay Ponomarev, Nicolas Gallagher, Noah Mendelsohn, Noah Slater, Noel Gordon, Nolan Waite, NoozNooz42, Norbert Lindenberg, Ojan Vafai, Olaf Hoffmann, Olav Junker Kjær, Oldřich Vetešník, Oli Studholme, Oliver Hunt, Oliver Rigby, Olivier Gendrin, Olli Pettay, oSand, Pablo Flouret, Patrick Garies, Patrick H. Lauke, Patrik Persson, Paul Adenot, Paul Cotton, Paul Norman, Per-Erik Brodin, Perry Smith, Peter Beverloo, Peter Karlsson, Peter Kasting, Peter Lemieux, Peter Moulder, Peter Occil, Peter Stark, Peter Van der Beken, Peter Winnberg, Peter-Paul Koch, Phil Pickering, Philip Taylor, Philip TAYLOR, Philippe De Ryck, Prateek Rungta, Pravir Gupta, Prayag Verma, 李普君 (Pujun Li), Rabab Gomaa, Rachid Finge, Rachel White, Rafael Weinstein, Rafał Miłecki, Raj Doshi, Rajas Moonka, Ralf Stoltze, Ralph Giles, Raphael Champeimont, Rebeca Ruiz, Remci Mizkur, Remco, Remy Sharp, Rene Saarsoo, Rene Stach, Ric Hardacre, Rich Clark, Rich Doughty, Richa Rupela, Richard Ishida, Richard Schwerdtfeger, Rigo Wenning, Rikkert Koppes, Rimantas Liubertas, Riona Macnamara, Rob Ennals, Rob Jellinghaus, Rob S, Robert Blaut, Robert Collins, Robert Kieffer, Robert Millan, Robert O’Callahan, Robert Sayre, Robin Berjon, Robin Schaufler, Rodger Combs, Rodney Rehm, Roland Steiner, Roma Matusevich, Roman Ivanov, Roy Fielding, Ruud Steltenpool, Ryan King, Ryan Rion, Ryosuke Niwa, S. Mike Dierken, Sailesh Panchang, Salvatore Loreto, Sam Dutton, Sam Kuper, Sam Ruby, Sam Weinig, Samuel Bronson, Samy Kamkar, Sander van Lambalgen, Sarven Capadisli, 佐藤雅之 (SATO Masayuki), Scott González, Scott Hess, Sean Fraser, Sean Hayes, Sean Hogan, Sean Knapp, Sebastian Markbåge, Sebastian Schnitzenbaumer, Seth Call, Seth Dillingham, Shannon Moeller, Shanti Rao, Shaun Inman, Shiki Okasaka, Shubheksha Jalan, Sierk Bornemann, Sigbjørn Finne, Sigbjørn Vik, Silver Ghost, Silvia Pfeiffer, Šime Vidas, Simo Sutela, Simon Montagu, Simon Spiegel, skeww, Smylers, Srirama Chandra Sekhar Mogali, Stanton McCandlish, Stefan Götz, Stefan Håkansson, Stefan Haustein, Stefan Santesson, Stefan Schumacher, Stefan Weiss, Steffen Meschkat, Stephane Corlosquet, Stephen Cunliffe, Stephen Ma, Stephen White, Steve Comstock, Steve Runyon, Steven Bennett, Steven Garrity, Steven Tate, Steven Wood, Stewart Brodie, Stuart Ballard, Stuart P Bentley, Stuart Langridge, Stuart Parmenter, Subramanian Peruvemba, Sunava Dutta, Susan Borgrink, Susan Lesch, Sylvain Pasche, T. J. Crowder, Tab Atkins-Bittner, Taiju Tsuiki, Takeshi Kurosawa, Takeshi Yoshino, Tantek Çelik, 田村健人 (TAMURA Kent), Taylor Hunt, Ted Mielczarek, Terrence Wood, Thijs van der Vossen, Thomas Broyer, Thomas Koetter, Thomas O’Connor, Tim Baxter, Tim Altman, Tim Johansson, TJ VanToll, Toby Inkster, Tobi Reif, Todd Moody, Tom Baker, Tom Pike, Tommy Thorsen, Tony Ross, Tooru Fujisawa, Travis Leithead, Trevor Saunders, triple-underscore, Tyler Close, Unor, Victor Carbune, Vipul Snehadeep Chawathe, Vitya Muhachev, Vladimir Katardjiev, Vladimir Vukićević, voracity, Wakaba, Wayne Carr, Wayne Pollock, Wellington Fernando de Macedo, Wes, Weston Ruter, Wilhelm Joys Andersen, Will Levine, William Chen, William Swanson, Wladimir Palant, Wojciech Mach, Wolfram Kriesing, Xan Gregg, xenotheme, Yang Chen, Yaroslaw, Ye-Kui Wang, Yehuda Katz, Yi-An Huang, Yngve Nysaeter Pettersen, Yoav Weiss, Yonathan Randolph, Yuzo Fujishima, Zhenbin Xu, Zoltan Herczeg, and Øistein E. Andersen,
for their useful comments, both large and small, that have led to changes to this specification over the years.
Thanks also to everyone who has ever posted about HTML to their blogs, public mailing lists, or forums, including all the contributors to the various W3C HTML WG lists and the various WHATWG lists.
The image in the introduction is based on a photo by Wonderlane. (CC BY 2.0)
The image of the wolf in the embedded content introduction is based on a photo by Barry O’Neill. (Public domain)
The image of the kettlebell swing in the embedded content introduction is based on a photo by kokkarina. (CC0 1.0)
The image of two cute kittens in a basket used in the context menu example is based on a photo by Alex G. (CC BY 2.0)
The Blue Robot Player sprite used in the canvas demo is based on a work by JohnColburn. (CC BY-SA 3.0)
The photograph of robot 148 climbing the tower at the FIRST Robotics Competition 2013 Silicon Valley Regional is based on a work by Lenore Edman. (CC BY 2.0)
Parts of this specification are © Copyright 2004-2014 Apple Inc., Mozilla Foundation, and Opera Software ASA. You are granted a license to use, reproduce and create derivative works of this document.