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http://software.hixie.ch/utilities/js/live-dom-viewer/?saved=2879 This is supported and returns true in every browser I've tested. It's used by jQuery, and is encountered on ~7% of pages by Chrome's use counter system: http://www.chromestatus.com/metrics/feature/timeline/popularity/162
Careful, it's "page loads" not "pages". 7% of page loads from Chrome installs with anonymous statistics reporting enabled. That's a ton of page loads. :) We can get "pages" numbers as well by crawling the web, but that's a different question. Regardless, it seems silly for this property to be marked as deprecated when it's seen on 7% of chrome page loads.
Thanks Eric, I'll make sure to be more precise when talking about use counters outside of blink-dev :)
The test in comment 0 tests something different than the bug subject line refers to. Can you elaborate on what this bug is about?
Oops, this is the correct test: http://software.hixie.ch/utilities/js/live-dom-viewer/?saved=2880 In other words, it looks like all browsers I've tested have a specified attribute on Attr objects. In Blink it's always true, but I haven't checked how it's implemented elsewhere. As an experiment, I dropped it from Blink and ran the jQuery tests, which caused 20 failures in LayoutTests/jquery/attributes.html. The fact that it's used by jQuery probably accounts for a lot of that 7%. I don't know for certain that specifying it is the best course of action, but it seems like the easiest fix.
https://github.com/whatwg/dom/commit/ab7d0c17491d94a93a463f04f6977ce689e9da0b
Thanks!