Window: transitionrun event

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

The transitionrun event is fired when a CSS transition is first created, i.e. before any transition-delay has begun.

Bubbles Yes
Cancelable No
Interface TransitionEvent
Event handler property ontransitionrun

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: transitionrun.


This code adds a listener to the transitionrun event:

window.addEventListener('transitionrun', () => {
  console.log('Transition is running but hasn't necessarily started transitioning yet');

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

window.ontransitionrun = () => {
  console.log('Transition started running');

See a live example of this event.


CSS Transitions Level 2
# transitionrun

Browser compatibility

BCD tables only load in the browser

See also