This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The Animation
.playbackRate
property of the Web Animations API returns or sets the playback rate of the animation.
Animations have a playback rate that provides a scaling factor from the rate of change of the animation's timeline
time values to the animation’s current time. The playback rate is initially 1
.
Syntax
var currentPlaybackRate = Animation.playbackRate; Animation.playbackRate = newRate;
Value
Takes a number that can be 0, negative, or positive. Negative values reverse the animation. The value is a scaling factor, so for example a value of 2 would double the playback rate.
Setting an animation’s playbackRate
to 0
effectively pauses the animation (however, its playstate
does not necessarily become paused
).
Examples
In the Growing/Shrinking Alice Game example, clicking or tapping the bottle causes Alice's growing animation (aliceChange
) to reverse, causing her to shrink:
var shrinkAlice = function() { aliceChange.playbackRate = -1; aliceChange.play(); } // On tap or click, Alice will shrink. bottle.addEventListener("mousedown", shrinkAlice, false); bottle.addEventListener("touchstart", shrinkAlice, false);
Contrariwise, clicking on the cake causes her to "grow," playing aliceChange
forwards again:
var growAlice = function() { aliceChange.playbackRate = 1; aliceChange.play(); } // On tap or click, Alice will grow. cake.addEventListener("mousedown", growAlice, false); cake.addEventListener("touchstart", growAlice, false);
In another example, the Red Queen's Race Game, Alice and the Red Queen are constantly slowing down:
setInterval( function() { // Make sure the playback rate never falls below .4 if (redQueen_alice.playbackRate > .4) { redQueen_alice.playbackRate *= .9; } }, 3000);
But clicking or tapping on them causes them to speed up by multiplying their playbackRate
:
var goFaster = function() { redQueen_alice.playbackRate *= 1.1; } document.addEventListener("click", goFaster); document.addEventListener("touchstart", goFaster);
Specifications
Specification | Status | Comment |
---|---|---|
Web Animations The definition of 'Animation.playbackRate' in that specification. |
Working Draft |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
playbackRate | Chrome Full support 39 | Edge Full support ≤79 | Firefox
Full support
48
| IE No support No | Opera Full support 26 | Safari No support No | WebView Android Full support 39 | Chrome Android Full support 39 | Firefox Android
Full support
48
| Opera Android Full support 26 | Safari iOS No support No | Samsung Internet Android Full support 4.0 |
Legend
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.
- Experimental. Expect behavior to change in the future.
- User must explicitly enable this feature.
- User must explicitly enable this feature.