Element: animationstart event

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since December 2019.

See full compatibility

The animationstart event is fired when a CSS Animation has started. If there is an animation-delay, this event will fire once the delay period has expired. A negative delay will cause the event to fire with an elapsedTime equal to the absolute value of the delay (and, correspondingly, the animation will begin playing at that time index into the sequence).

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

addEventListener("animationstart", (event) => { })

onanimationstart = (event) => { }

Event type

An AnimationEvent. Inherits from Event.

Event properties

Also inherits properties from its parent Event.

AnimationEvent.animationName Read only: A string containing the value of the animation-name that generated the animation.
AnimationEvent.elapsedTime Read only: A float giving the amount of time the animation has been running, in seconds, when this event fired, excluding any time the animation was paused. For an animationstart event, elapsedTime is 0.0 unless there was a negative value for animation-delay, in which case the event will be fired with elapsedTime containing (-1 * delay).
AnimationEvent.pseudoElement Read only: A string, starting with '::', containing the name of the pseudo-element the animation runs on. If the animation doesn't run on a pseudo-element but on the element, an empty string: ''.

Examples

This listens for the animationstart event and logs a message when it is fired:

const animated = document.querySelector(".animated");

animated.addEventListener("animationstart", () => {
  console.log("Animation started");
});

The same, but using onanimationstart:

const animated = document.querySelector(".animated");

animated.onanimationstart = () => {
  console.log("Animation started");
};

Live example

HTML

html

<div class="animation-example">
  <div class="container">
    <p class="animation">You chose a cold night to visit our planet.</p>
  </div>
  <button class="activate" type="button">Activate animation</button>
  <div class="event-log"></div>
</div>

CSS

css

.container {
  height: 3rem;
}

.event-log {
  width: 25rem;
  height: 2rem;
  border: 1px solid black;
  margin: 0.2rem;
  padding: 0.2rem;
}

.animation.active {
  animation-duration: 2s;
  animation-name: slide-in;
  animation-iteration-count: 2;
}

@keyframes slide-in {
  from {
    transform: translateX(100%) scaleX(3);
  }
  to {
    transform: translateX(0) scaleX(1);
  }
}

JavaScript

const animation = document.querySelector("p.animation");
const animationEventLog = document.querySelector(
  ".animation-example>.event-log",
);
const applyAnimation = document.querySelector(
  ".animation-example>button.activate",
);
let iterationCount = 0;

animation.addEventListener("animationstart", () => {
  animationEventLog.textContent = `${animationEventLog.textContent}'animation started' `;
});

animation.addEventListener("animationiteration", () => {
  iterationCount++;
  animationEventLog.textContent = `${animationEventLog.textContent}'animation iterations: ${iterationCount}' `;
});

animation.addEventListener("animationend", () => {
  animationEventLog.textContent = `${animationEventLog.textContent}'animation ended'`;
  animation.classList.remove("active");
  applyAnimation.textContent = "Activate animation";
});

animation.addEventListener("animationcancel", () => {
  animationEventLog.textContent = `${animationEventLog.textContent}'animation canceled'`;
});

applyAnimation.addEventListener("click", () => {
  animation.classList.toggle("active");
  animationEventLog.textContent = "";
  iterationCount = 0;
  const active = animation.classList.contains("active");
  applyAnimation.textContent = active
    ? "Cancel animation"
    : "Activate animation";
});

Result

Specifications

Specification
CSS Animations Level 1 # eventdef-globaleventhandlers-animationstart

Browser compatibility

	desktop					mobile
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS
`animationstart` event	Chrome – Partial support Chrome 43 – 78 (Release date: 2015-05-19) footnote Partial support footnote The `onanimationstart` event handler property is not supported. To listen to this event, use `document.addEventListener('animationstart', function() {});`. Chrome – Full support Chrome 81 (Release date: 2020-04-07) prefix prefix Implemented with the vendor prefix: webkit Chrome – Full support Chrome 79 (Release date: 2019-12-10) footnote Full support	Edge – Partial support Edge 12 – 17 (Release date: 2015-07-29) footnote Partial support footnote The `onanimationstart` event handler property is not supported. To listen to this event, use `document.addEventListener('animationstart', function() {});`. Edge – Full support Edge 81 (Release date: 2020-04-13) prefix prefix Implemented with the vendor prefix: webkit Edge – Full support Edge 18 (Release date: 2018-10-02) footnote Full support	Firefox – Partial support Firefox 5 – 50 (Release date: 2011-06-21) footnote Partial support footnote The `onanimationstart` event handler property is not supported. To listen to this event, use `document.addEventListener('animationstart', function() {});`. Firefox – Full support Firefox 51 (Release date: 2017-01-24) footnote Full support	Opera – Partial support Opera 30 – 65 (Release date: 2015-06-09) footnote Partial support footnote The `onanimationstart` event handler property is not supported. To listen to this event, use `document.addEventListener('animationstart', function() {});`. Opera – Full support Opera 68 (Release date: 2020-04-22) prefix prefix Implemented with the vendor prefix: webkit Opera – Full support Opera 66 (Release date: 2020-01-07) footnote Full support	Safari – Full support Safari 9 (Release date: 2015-09-30) footnote Full support	Chrome Android – Partial support Chrome Android 43 – 78 (Release date: 2015-05-27) footnote Partial support footnote The `onanimationstart` event handler property is not supported. To listen to this event, use `document.addEventListener('animationstart', function() {});`. Chrome Android – Full support Chrome Android 81 (Release date: 2020-04-07) prefix prefix Implemented with the vendor prefix: webkit Chrome Android – Full support Chrome Android 79 (Release date: 2019-12-17) footnote Full support	Firefox for Android – Partial support Firefox for Android 5 – 50 (Release date: 2011-06-21) footnote Partial support footnote The `onanimationstart` event handler property is not supported. To listen to this event, use `document.addEventListener('animationstart', function() {});`. Firefox for Android – Full support Firefox for Android 51 (Release date: 2017-01-24) footnote Full support	Opera Android – Partial support Opera Android 30 – 56 (Release date: 2015-06-10) footnote Partial support footnote The `onanimationstart` event handler property is not supported. To listen to this event, use `document.addEventListener('animationstart', function() {});`. Opera Android – Full support Opera Android 58 (Release date: 2020-05-13) prefix prefix Implemented with the vendor prefix: webkit Opera Android – Full support Opera Android 57 (Release date: 2020-03-30) footnote Full support	Safari on iOS – Full support Safari on iOS 9 (Release date: 2015-09-16) footnote Full support	Samsung Internet – Partial support Samsung Internet 4 – 11.2 (Release date: 2016-03-11) footnote Partial support footnote The `onanimationstart` event handler property is not supported. To listen to this event, use `document.addEventListener('animationstart', function() {});`. Samsung Internet – Full support Samsung Internet 13 (Release date: 2020-12-02) prefix prefix Implemented with the vendor prefix: webkit Samsung Internet – Full support Samsung Internet 12 (Release date: 2020-06-19) footnote Full support	WebView Android – Partial support WebView Android 43 – 78 (Release date: 2015-05-27) footnote Partial support footnote The `onanimationstart` event handler property is not supported. To listen to this event, use `document.addEventListener('animationstart', function() {});`. WebView Android – Full support WebView Android 81 (Release date: 2020-04-07) prefix prefix Implemented with the vendor prefix: webkit WebView Android – Full support WebView Android 79 (Release date: 2019-12-17) footnote Full support	WebView on iOS – Full support WebView on iOS 9 (Release date: 2015-09-16) footnote Full support

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Full support: Full support
Partial support: Partial support
: Requires a vendor prefix or different name for use.
: Has more compatibility info.

Element: animationstart event

HTML

CSS

JavaScript

Result

Legend