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 {domxref("AnimationEffectTimingProperties")}} dictionary's easing property in the Web Animations API specifies the timing function used to scale the time to produce easing effects, where easing is the rate of the animation's change over time.

Element.animate(), KeyframeEffectReadOnly(), and KeyframeEffect() all accept an object of timing properties including easing. The value of easing corresponds directly to AnimationEffectTimingReadOnly.easing in timing objects returned by AnimationEffectReadOnly, KeyframeEffectReadOnly, and KeyframeEffect.


var timingProperties = {
  easing: <single-transition-timing-function>

timingProperties.easing = <single-transition-timing-function>


A string defining the timing function to use for easing transitions during the animation process. Accepts several pre-defined DOMString values, a steps() timing function like steps(5, end), or a custom cubic-bezier value like cubic-bezier(0.42, 0, 0.58, 1). Defaults to linear. Available values include:

A constant rate of change, neither accelerating nor deccelerating. 
cubic-bezier(<number>, <number>, <number>, <number>)
A diagram showing the points of a cubic bezier timing function.
Specifies a cubic Bézier timing function. The four numbers specify points P1 and P2 of the curve as (x1, y1, x2, y2). Both x values must be in the range [0, 1] or the definition is invalid.
A decelerated rate of change, going from fast to slow. Equivalent to cubic-bezier(0.25, 0.1, 0.25, 1).
An accelerated rate of change, going from slow to fast. Equivalent to cubic-bezier(0.42, 0, 1, 1).
Another decelerated rate of change, going from fast to slow. Equivalent to cubic-bezier(0, 0, 0.58, 1).
This rate of change speeds up in the middle. Equivalent to cubic-bezier(0.42, 0, 0.58, 1).
steps(<integer>[, [ start | end ] ]?)
A diagram of the various steps timing functions.
Specifies a step timing function. The first parameter specifies the number of intervals in the function. It must be a positive integer (greater than 0). The second parameter, which is optional, specifies the point at which the change of values occur within the interval. If the second parameter is omitted, it is given the value end.
Equivalent to steps(1, start)
Equivalent to steps(1, end).


In the Red Queen's Race example, we animate Alice and the Red Queen by passing an easing of steps(7, end) to animate():

// Define the key frames
var spriteFrames = [
  { transform: 'translateY(0)' },
  { transform: 'translateY(-100%)' }   

// Get the element that represents Alice and the Red Queen
var redQueen_alice_sprite = document.getElementById('red-queen_and_alice_sprite');

// Animate Alice and the Red Queen using steps()
var redQueen_alice = redQueen_alice_sprite.animate(
spriteFrames, {
  easing: 'steps(7, end)',
  direction: "reverse",
  duration: 600,
  playbackRate: 1,
  iterations: Infinity


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

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support (Yes) 48 (48)[1] No support (Yes) No support
Feature Android Android Webview Chrome for Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile
Basic support ? ? ? 48.0 (48)[1] ? No support No support No support

[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