Adds the pending attribute to the Web Animations API. A pending animation is one that is waiting on an asynchronous operation that affects the play state. Adding support for this attribute does not affect the rendering or timing of animations, but simply exposes the signal.


Animation.pending has been in the spec for some time and we are playing catch up in Chrome. Firefox and Safari already support this API. The main driving force behind Animation.pending is for testing and diagnostics. Animations have a lot of asynchronous moving parts, and it is easier to verify correctness of the code when we can measure that JavaScript code will induce an asynchronous change to the play state of an animations. Consistency across platforms is a strong motivating force. With this change, Chrome is more in line with other browsers. Adding the Animation.pending attribute fixes 30 WPT test failures for web animations.




Specification link

Specification being incubated in a Community Group

Status in Chromium


Enabled by default (tracking bug)

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.


Last updated on 2021-12-13