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 March 2020.
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 ananimationstart
event,elapsedTime
is0.0
unless there was a negative value foranimation-delay
, in which case the event will be fired withelapsedTime
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
<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
Specifications
Specification |
---|
CSS Animations Level 1 # eventdef-globaleventhandlers-animationstart |
Browser compatibility
BCD tables only load in the browser