Window: transitionstart event

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The transitionstart event is fired when a CSS transition has actually started, i.e., after any transition-delay has ended.

Bubbles Yes
Cancelable No
Interface TransitionEvent
Event handler property GlobalEventHandlers.ontransitionstart

The original target for this event is the Element that had the transition applied. You can listen for this event on the Window interface to handle it in the capture or bubbling phases. For full details on this event please see the page on HTMLElement: transitionstart.

Examples

This code adds a listener to the transitionstart event:

window.addEventListener('transitionstart', () => {
  console.log('Started transitioning');
});

The same, but using the ontransitionstart property instead of addEventListener():

window.ontransitionrun = () => {
  console.log('Started transitioning');
};

See a live example of this event.

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
transitionstart_event
No
No
53
No
?
13.1
12
No
No
53
?
13.4
12
No

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/Window/transitionstart_event