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.
Theanimationstart event is fired when aCSS Animation has started. If there is ananimation-delay, this event will fire once the delay period has expired. A negative delay will cause the event to fire with anelapsedTime 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 likeaddEventListener(), or set an event handler property.
addEventListener("animationstart", (event) => { })onanimationstart = (event) => { }Event type
AnAnimationEvent. Inherits fromEvent.
Event properties
Also inherits properties from its parentEvent.
AnimationEvent.animationNameRead onlyA string containing the value of the
animation-namethat generated the animation.AnimationEvent.elapsedTimeRead onlyA
floatgiving the amount of time the animation has been running, in seconds, when this event fired, excluding any time the animation was paused. For ananimationstartevent,elapsedTimeis0.0unless there was a negative value foranimation-delay, in which case the event will be fired withelapsedTimecontaining(-1 * delay).AnimationEvent.pseudoElementRead onlyA string, starting with
'::', containing the name of thepseudo-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 theanimationstart event and logs a message when it is fired:
const animated = document.querySelector(".animated");animated.addEventListener("animationstart", () => { console.log("Animation started");});The same, but usingonanimationstart:
const animated = document.querySelector(".animated");animated.onanimationstart = () => { console.log("Animation started");};Live example
HTML
<div> <div> <p>You chose a cold night to visit our planet.</p> </div> <button type="button">Activate animation</button> <div></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 |