Vanilla event delegation

event_delegate.js

var delegate = (function(){

	var match = (function(){
		var guineaPig = document.createElement('div');
		if(guineaPig.matchesSelector) return function(elem, selector){
			return elem.matchesSelector(selector);
		};
		if(guineaPig.mozMatchesSelector) return function(elem, selector){
			return elem.mozMatchesSelector(selector);
		};
		if(guineaPig.webkitMatchesSelector) return function(elem, selector){
			return elem.webkitMatchesSelector(selector);
		};
		return function(elem, selector, elems){
			for(var i=0,len=elems.length; i < len; i++){
				if(elems[i] === elem) return true;
			}
			return false;
		};
	})();

	return function(baseElement, event, selector, callback){
		var on = 'addEventListener';
		if(!baseElement.addEventListener){
			event = 'on'+event;
			on = 'attachEvent';
		}
		baseElement[on](event, function(e){
			var _elems;
			var target = e.target || e.srcElement;
			if(!baseElement.mozMatchesSelector || !baseElement.webkitMatchesSelector){
				_elems = baseElement.querySelectorAll(selector);
			}
			if(match(target, selector, _elems)){
				return callback.call(target, e);
			}
			if(target.parentNode){
				var _parent = target;
				while(_parent = _parent.parentNode){
					if(match(_parent, selector, _elems)){
						return callback.call(_parent, e);
					}
				}
			}
		});
	};
})();

/** Example usage **/

delegate(document.body, 'click', 'li .link', function(e){
    // do something, `this` should point to element that was matched...
});