HTMLElement: animationstart event - Web APIs 编辑

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).

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

Browser compatibility

BCD tables only load in the browser

See also

• CSS Animations
• Using CSS Animations
• AnimationEvent
• Related events: animationend, animationiteration, animationcancel
• This event on Document targets: animationstart
• This event on Window targets: animationstart