Obsolete since Gecko 11 (Firefox 11 / Thunderbird 11 / SeaMonkey 2.8)
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

Warning: This non-standard event handler has not worked for several releases, and has been removed in Gecko 11.0 (Firefox 11.0 / Thunderbird 11.0 / SeaMonkey 2.8).


An event handler for the MozBeforePaint event. This is used in concert with the window.mozRequestAnimationFrame() method to perform smooth, synchronized animations from JavaScript code.


window.onmozbeforepaint = funcRef;
  • funcRef is the handler function.


See window.mozRequestAnimationFrame() for an example.


This event fires immediately before the browser window is repainted, if the event has been requested by one or more scripts calling window.mozRequestAnimationFrame(). The event handler receives as an input parameter an event whose timeStamp property is the time, in milliseconds since epoch, that is the "current time" for the current animation frame. This time is the same for all animations being run in the same browser window, including those using the window.mozRequestAnimationFrame() method, CSS transitions, and SMIL animations.


Not part of a specification.

Document Tags and Contributors

 Contributors to this page: fscholz, MHasan, teoli, Sheppy, Bzbarsky
 Last updated by: fscholz,