Callback on CSS transition

I know that Safari implements a webkitTransitionEnd callback that you can attach directly to the element with the transition.

Their example (reformatted to multiple lines):

box.addEventListener( 
     'webkitTransitionEnd', 
     function( event ) { 
         alert( "Finished transition!" ); 
     }, false );

Yes, if such things are supported by the browser, then an event is triggered when the transition completes. The actual event however, differs between browsers:

• Webkit browsers (Chrome, Safari) use webkitTransitionEnd
• Firefox uses transitionend
• IE9+ uses msTransitionEnd
• Opera uses oTransitionEnd

However you should be aware that webkitTransitionEnd doesn't always fire! This has caught me out a number of times, and seems to occur if the animation would have no effect on the element. To get around this, it makes sense to use a timeout to fire the event handler in the case that it's not been triggered as expected. A blog post about this problem is available here: http://www.cuppadev.co.uk/the-trouble-with-css-transitions/ <-- 500 Internal Server Error

With this in mind, I tend to use this event in a chunk of code that looks a bit like this:

var transitionEndEventName = "XXX"; //figure out, e.g. "webkitTransitionEnd".. 
var elemToAnimate = ... //the thing you want to animate..
var done = false;
var transitionEnded = function(){
     done = true;
     //do your transition finished stuff..
     elemToAnimate.removeEventListener(transitionEndEventName,
                                        transitionEnded, false);
};
elemToAnimate.addEventListener(transitionEndEventName,
                                transitionEnded, false);

//animation triggering code here..

//ensure tidy up if event doesn't fire..
setTimeout(function(){
    if(!done){
        console.log("timeout needed to call transition ended..");
        transitionEnded();
    }
}, XXX); //note: XXX should be the time required for the
        //animation to complete plus a grace period (e.g. 10ms) 

Note: to get the transition event end name you can use the method posted as the answer in: How do I normalize CSS3 Transition functions across browsers?.

Note: this question is also related to: - CSS3 transition events