Animation.updatePlaybackRate() lets you seamlessly transition the playback rate of an animation such that there is no visible jump in the animation. Current time is preserved at the instance the new playback rate takes effect.
Animation.updatePlaybackRate() provides a means of ensuring that a change in playback rate results in a smooth transition. Current time is preserved at the moment the new playback rate takes effect. This method is presently available on Firefox and under development for Safari. Adding support in Chrome ensures consistency across browsers.
Docs: https://drafts.csswg.org/web-animations/#the-animation-interface https://drafts.csswg.org/web-animations/#seamlessly-updating-the-playback-rate-of-an-animation
Samples: https://wpt.fyi/results/web-animations/interfaces/Animation/idlharness.window.html?label=master https://wpt.fyi/results/web-animations/timing-model/animations/seamlessly-updating-the-playback-rate-of-an-animation.html?label=master
Explainers: https://developer.mozilla.org/en-US/docs/Web/API/Animation/updatePlaybackRate