transition_sniffing.js

function whichTransitionEvent(){
    var t;
    var el = document.createElement('fakeelement');
    var transitions = {
      'transition':'transitionend',
      'MSTransition':'msTransitionEnd',
      'MozTransition':'transitionend',
      'WebkitTransition':'webkitTransitionEnd'
    }

    for(t in transitions){
        if( el.style[t] !== undefined ){
            return transitions[t];
        }
    }
}

I have successfully used callbacks by registering the events for all browsers so i would recommend that.
eg: this.$el.on('webkitTransitionEnd transitionend msTransitionEnd oTransitionEnd', function(event) { ...

You shouldn't register all events. The reason for this is that at least Chrome as of version 29 will fire off both webkitTransitionEnd and transitionend. So your function will fire twice.

The way you get around firing function twice is to add a namespace to the event name and turning them all off once one of them have been executed.

this.$el.on('webkitTransitionEnd.blah transitionend.blah msTransitionEnd.blah oTransitionEnd.blah', function(event) {
  this.$el.off(".blah");
}

Obviously, replace blah with your own namespace.