Element: animationstart event

{{APIRef}}

The animationstart event is fired when a CSS Animation has started. If there is an {{cssxref("animation-delay")}} , this event will fire once the delay period has expired. A negative delay will cause the event to fire with an {{domxref("AnimationEvent/elapsedTime", "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 {{domxref("EventTarget.addEventListener", "addEventListener()")}} , or set an event handler property.

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

onanimationstart = (event) => {};

Event type

An {{domxref("AnimationEvent")}} . Inherits from {{domxref("Event")}} .

{{InheritanceDiagram("AnimationEvent")}}

Event properties

Also inherits properties from its parent {{domxref("Event")}} .

{{domxref("AnimationEvent.animationName")}} {{ReadOnlyInline}}
- : A string containing the value of the {{cssxref("animation-name")}} that generated the animation.
{{domxref("AnimationEvent.elapsedTime")}} {{ReadOnlyInline}}
- : 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 {{cssxref("animation-delay")}} , in which case the event will be fired with elapsedTime containing (-1 * delay).
{{domxref("AnimationEvent.pseudoElement")}} {{ReadOnlyInline}}
- : 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

<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: 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

{{ EmbedLiveSample('Live_example', '100%', '150px') }}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

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