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 KeyframeEffect() constructor of the Web Animations API returns a new KeyframeEffect object instance.


var keyframes = new keyframeEffect(element, keyframeSet, keyframeOptions);


The DOM element to be animated, or null.
An keyframe object or null.
keyframeOptions Optional

Either an integer representing the animation's duration (in milliseconds), or an Object containing one or more of the following:

AnimationEffectTimingProperties.delay Optional
The number of milliseconds to delay the start of the animation. Defaults to 0.
AnimationEffectTimingProperties.direction Optional
Whether the animation runs forwards (normal), backwards (reverse), switches direction after each iteration (alternate), or runs backwards and switches direction after each iteration (alternate-reverse). Defaults to normal.
AnimationEffectTimingProperties.duration Optional
The number of milliseconds each iteration of the animation takes to complete. Defaults to 0.
AnimationEffectTimingProperties.easing Optional
The rate of the animation's change over time. Accepts the pre-defined values linearease, ease-in, ease-out, and ease-in-out, or a custom cubic-bezier value like cubic-bezier(0.42, 0, 0.58, 1). Defaults to linear.
AnimationEffectTimingProperties.endDelay Optional
The number of milliseconds to delay after the end of an animation. This is primarily of use when sequencing animations based on the end time of another animation. Defaults to 0
AnimationEffectTimingProperties.fill Optional
Dictates whether the animation's effects should be reflected by the element(s) prior to playing (backwards), retained after the animation has completed playing (forwards), or both. Defaults to none.
AnimationEffectTimingProperties.iterationStart Optional
Describes at what point in the iteration the animation should start. 0.5 would indicate starting halfway through the first iteration for example, and with this value set, an animation with 2 iterations would end halfway through a third iteration. Defaults to 0.0.
AnimationEffectTimingProperties.iterations Optional
The number of times the animation should repeat. Defaults to 1, and can also take a value of infinity to make it repeat infinitely.

Future Options

The following options are currently not shipped anywhere, but will be added in the near future:

Determines how values are combined between this animation and the element's underlying values.
Determines how values build from iteration to iteration in the current animation.
Determines how keyframes without temporal offsets should be distributed during the animation's duration.


In the Follow the White Rabbit example, the KeyframeEffect constructor is used to create a set of keyframes that dictate how the White Rabbit should animate down the hole:

 var rabbitDownKeyframes = new KeyframeEffect( 
    whiteRabbit, // element to animate
      { transform: 'translateY(0%)' }, // keyframe 
      { transform: 'translateY(100%)' } // keyframe
    { duration: 3000, fill: 'forwards' } // keyframe options


Specification Status Comment
Web Animations
The definition of 'keyframeEffect()' in that specification.
Working Draft Editor's draft.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support No support No support No support No support No support
Feature Android Android Webview Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support No support No support No support No support No support No support No support No support

See also


© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

Animation API Constructor Experimental KeyframeEffect Reference waapi web animations api