This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
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
// getting the playbackRate var currentPlaybackRate = element.playbackRate; // setting playbackRate element.playbackRate = 1;
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.
Note: 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
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 39.0 | 48 (48) | No support | No support | No support |
Feature | Android | Android Webview | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|
Basic support | No support | 39.0 | 48.0 (48) | No support | No support | No support | 39.0 |