Web-Facing Change PSA: Interoperable dispatch timing for transitionrun and media query events

[Chromestatus]

Contact emails

mus...@chromium.org

Specification

https://html.spec.whatwg.org/multipage/webappapis.html#event-loop-processing-model

Summary

Aligns Blink's dispatch timing for animation "transitionrun" event and media query "change" event with the spec, making the timing interoperable with Gecko and WebKit. More precisely, as per HTML window event loop specification, "transitionrun" events will be fired at Step 3.11 even for animations created earlier in the same iteration (instead of delaying them for a later iteration), and the media query "change" event will be fired at Step 3.10 before firing any pending animation events (instead of intermixing them with animation events at Step 3.11).

Blink component

Blink>Animation

Web Feature ID

No information provided

Risks

Interoperability and Compatibility

Interoperability: no risk. This makes Blink interoperable with Gecko and WebKit. Compatibility risk: very low. The change only affects the relative order of media query "change" events and animation "transitionrun" events with respect to rAF callbacks, and this subtle timing adjustment is not expected to be noticeable to web applications.

Gecko: No signal

WebKit: No signal

Web developers: No signals

Other signals:

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

No information provided

Debuggability

This feature is barely observable by developers, and is debuggable through event listeners and rAF callbacks.

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

Yes

Is this feature fully tested by web-platform-tests?

Yes
https://wpt.fyi/results/html/webappapis/scripting/event-loops/new-scroll-event-dispatched-at-next-updating-rendering-time.html?label=master&label=experimental&aligned&view=interop

Tracking bug

https://crbug.com/397737222

Estimated milestones

Shipping on desktop	153
Shipping on Android	153
Shipping on WebView	153

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/6312504658624512

This intent message was generated by Chrome Platform Status.