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

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

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 39.0 48 (48)[1] 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)[1] No support No support No support 39.0

[1] The Web Animations API is only enabled by default in Firefox Developer Edition and Nightly builds. You can enable it in beta and release builds by setting the preference dom.animations-api.core.enabled to true, and can disable it in any Firefox version by setting this preference to false.

See also

Document Tags and Contributors

 Last updated by: Sheppy,