HTMLElement: animationstart event

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).

Bubbles Yes
Cancelable No
Interface AnimationEvent
Event handler property onanimationstart

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

<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

.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: slidein;
  animation-iteration-count: 2;
}

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

JS

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;
  let active = animation.classList.contains('active');
  if (active) {
    applyAnimation.textContent = "Cancel animation";
  } else {
    applyAnimation.textContent = "Activate animation";
  }
});

Result

Specifications

Specification Status Comment
CSS Animations Working Draft Initial definition

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
animationstart eventChrome Full support 43Edge ? Firefox Full support 51IE ? Opera ? Safari ? WebView Android Full support 43Chrome Android Full support 43Edge Mobile ? Firefox Android Full support 51Opera Android ? Safari iOS ? Samsung Internet Android ?

Legend

Full support  
Full support
Compatibility unknown  
Compatibility unknown

See also

Document Tags and Contributors

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