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 Web Animations API dictionary AnimationEffectTimingProperties's iterations property specifies the number of times the animation should repeat. The default value is 1, indicating that it should only play once, but you can set it to any floating-point value (including positive Infinity defaults to 1, and can also take a value of Infinity to make it loop infinitely. 

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


var timingProperties = {
  iterations: numberOfIterations

timingProperties.iterations = numberOfIterations;


A floating-point value specifying the number of times the animation sequence will play through. Any value from 0 (don't play the animation at all) to positive Infinity (run the animation indefinitely) is supported. Defaults to 1, meaning the animation sequence plays through once then stops automatically.


An attempt was made to set the value of this property to a negative number or NaN. The property's value is left unchanged.


In the Forgotten Key example, Alice waves her arm up and down the entire time the page is open by passing Infinity as the value for her iterations property:

// Get Alice's arm, and wave it up and down
  { transform: 'rotate(10deg)' }, 
  { transform: 'rotate(-40deg)' }
], {
  easing: 'steps(2, end)',
  iterations: Infinity,
  direction: 'alternate',
  duration: 600


Specification Status Comment
Web Animations
The definition of 'iterations' 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