This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The duration property of the dictionary AnimationEffectTimingProperties in the Web Animations API specifies the duration in milliseconds that a single iteration (from beginning to end) the animation should take to complete.

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


var timingProperties = {
  duration: durationInMilliseconds | "auto"

timingProperties.duration = durationInMilliseconds | "auto";


The number of milliseconds long a single beginning-to-end iteration of the animation should take. The default is "auto". This value must not be negative; otherwise, it can have any value (including positive infinity).

Currently, a value of "auto" is the same as specifying 0.0. This is a forwards-compatiblity measure since in the future, "auto" will be expanded to take into account the duration of any child effects. Consider using "auto" rather than 0 if that makes sense.


The specified value is either a string other than "auto", a number less than zero, NaN, or some other type of object entirely.


In the Pool of Tears example, each tear is passed a random duration via its timing object:

// Randomizer function
var getRandomMsRange = function(min, max) {
  return Math.random() * (max - min) + min;

// Loop through each tear
tears.forEach(function(el) { 

  // Animate each tear
       delay: getRandomMsRange(-1000, 1000), // randomized for each tear
       duration: getRandomMsRange(2000, 6000), // randomized for each tear
       iterations: Infinity,
       easing: "cubic-bezier(0.6, 0.04, 0.98, 0.335)"


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

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

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 ? ? ?[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