On Wednesday, February 9, 2022 at 2:49:55 AM UTC+1 Mike Taylor wrote:
> Hey Xiaocheng, > > Thanks for working on improving interop! A few thoughts and questions > below. > > On 2/8/22 7:25 PM, Xiaocheng Hu wrote: > > Contact emails xiaoche...@chromium.org > > Explainer None > > Specification None. Not a standard feature. > > Summary > > Event.path is a non-standard API that returns the event's path, which is > an array of the objects on which listeners will be invoked. It is supported > by Blink only, causing web compatibility issues. Web developers should > switch to the equivalent standard API Event.composedPath(), which returns > the same result. > > > Blink component Blink>DOM > <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EDOM> > > TAG review > > TAG review status Not applicable > > Risks > > > Interoperability and Compatibility > > The removal of this API should improve interoperability, as it's supported > by Blink only. It still has 18% usage as of Feb 2022 ( > https://chromestatus.com/metrics/feature/timeline/popularity/345), so we > will only deprecate it for now, and will not remove it before the usage > drops low enough. We expect low compatibility risks, since there is an > equivalent standard API (Event.composedPath()) by all browsers, and the > following polyfill should also keep existing sites functioning with minimum > changes: > > 18% is a _lot_ of usage. So much that I'm surprised there aren't dozens of > compat bugs reported against Firefox. In > https://bugzilla.mozilla.org/show_bug.cgi?id=1697590#c0 there are only 2 > linked site bugs. And there's only 3 in > https://github.com/webcompat/web-bugs/issues?q=is%3Aissue+composedPath > (the last one being from 2019). > > I wonder how much of that 18% is feature detection and fallback codepaths > <https://github.com/search?l=JavaScript&q=composedPath+event.path&type=Code> > . > Yeah, that 18% is unreasonably high... I think it'd be good to add a non-IDL based counter that counts when both Event::path <https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/dom/events/event.cc;l=287;bpv=1;bpt=0> and Event::composedPath <https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/dom/events/event.cc;l=293;bpv=1;bpt=0> are accessed. (e.g. by adding 2 booleans or a bitmask on Event indicating when any of them was touched and triggering the counter when both have been) Then we can assume that counts feature-detection/fallback and subtract that counter from the 18%. > Are we aware of bug reports from Apple caused by event.path? I'm not able > to find any on bugs.webkit.org, but I could be doing it wrong. > > Have you thought of ways to measure when event.path is called, and > event.composedPath isn't (not sure if that's even possible)? Maybe that > would show it's actually safe to remove. > > if (!Event.prototype.path) { Object.defineProperty(Event.prototype, > 'path', { get() { return this.composedPath(); } }); } > > Given how simple this appears to be, I wonder if a better approach would > be to ask Mozilla and Apple if they would be willing to accept patches to > make event.path a legacy alias to event.composedPath - and then we can spec > it in DOM or Compat. The alternative is to send deprecation messages for > possibly a very long time, which doesn't really improve the compat > situation for a very long time. Or, we can figure out how to measure the > actual non-fallback usage of event.path and go from there. > > > > Gecko: No signal Firefox does not support Event.path > > WebKit: No signal Safari does not support Event.path > > Web developers: Positive ( > https://github.com/web-platform-tests/interop-2022/issues/26) > > That should probably be counted as positive support from Mozilla, rather > than webdev support (no offense to James). > > > Other signals: > > > Debuggability > > Usage of this deprecated feature will be reported to the DevTools Issues > Tab. > > > Is this feature fully tested by web-platform-tests > <https://chromium.googlesource.com/chromium/src/+/master/docs/testing/web_platform_tests.md> > ? No > > Flag name > > Requires code in //chrome? False > > Tracking bug https://bugs.chromium.org/p/chromium/issues/detail?id=1277431 > > Estimated milestones > > No milestones specified > > > Link to entry on the Chrome Platform Status > https://chromestatus.com/feature/5726124632965120 > > This intent message was generated by Chrome Platform Status > <https://chromestatus.com/>. > > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to blink-dev+unsubscr...@chromium.org. > To view this discussion on the web visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAFqEGha_iNax9r8%2BXVQK%2Bf3hEdu5z-MDAh44FbKMOuAnrHL2Ew%40mail.gmail.com > > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAFqEGha_iNax9r8%2BXVQK%2Bf3hEdu5z-MDAh44FbKMOuAnrHL2Ew%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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