주로 메모리 유출에 대한 개선

(function() {
	window.EventUtils = {
		eventFuncs : [],

		addEvent : function(o, n, f) {
			var el, id;

			// Resolve element by id if needed
			o = typeof(o) == 'string' ? document.getElementById(o) : o;

			if (o.attachEvent) {
				// Since we can't use attachEvent we need to generate an unique id for the object
				// and place functions in an array one for each object
				el = EventUtils.eventFuncs;
				id = o._evtID;

				if (!el[id]) {
					// Generate new unique id
					id = o._evtID = el.length;

					// Add event listener old fashion way instead of attachEvent
					o['on' + n] = function() {
						var i, l, e = window.event, li;

						e.target = e.srcElement; // Force W3C style

						// Execute each event listener in order
						for (i = 0, li = el[e.target._evtID], l = li.length; i < l; i++)
							li[i](e);
					};

					// Create array with first function
					el[id] = [f];
				} else
					el[id].push(f); // Push in more functions

				// Fix the IE leak
				o = null;
			} else if (o.addEventListener)
				o.addEventListener(n, f, false);
			else
				o['on' + n] = f;

			return f;
		},

		removeEvent : function(o, n, f) {
			var i, li;

			// Resolve element by id if needed
			o = typeof(o) == 'string' ? document.getElementById(o) : o;

			if (o.detachEvent) {
				li = EventUtils.eventFuncs[o._evtID];

				if (li) {
					// Detach event listener by looking for it and remove it from the array
					for (i = 0; i < li.length; i++) {
						if (li[i] === f)
							li.splice(i, 1);
					}
				}
			} else if (o.removeEventListener)
				o.removeEventListener(n, f, false);
			else
				o['on' + n] = null;
		}
	};
})();

(function() {
window.EventUtils = {
eventFuncs : [],
addEvent : function(o, n, f) {
var el, id;
//Resolve element by id if needed
o = typeof(o) == 'string' ? document.getElementById(o) : o;
if (o.attachEvent) {
//Since we can't use attachEvent we need to generate an unique id for the object
//and place functions in an array one for each object
el = EventUtils.eventFuncs;
id = o._evtID;
if (!el[id]) {
//Generate new unique id
id = o._evtID = el.length;
//Add event listener old fashion way instead of attachEvent
o['on' + n] = function() {
var i, l, e = window.event, li;
e.target = e.srcElement;//Force W3C style
//Execute each event listener in order
for (i = 0, li = el[e.target._evtID], l = li.length; i < l; i++)
li[i](e);
};
//Create array with first function
el[id] = [f];
} else
el[id].push(f);//Push in more functions
//Fix the IE leak
o = null;
} else if (o.addEventListener)
o.addEventListener(n, f, false);
else
o['on' + n] = f;
return f;
},
removeEvent : function(o, n, f) {
var i, li;
//Resolve element by id if needed
o = typeof(o) == 'string' ? document.getElementById(o) : o;
if (o.detachEvent) {
li = EventUtils.eventFuncs[o._evtID];
if (li) {
//Detach event listener by looking for it and remove it from the array
for (i = 0; i < li.length; i++) {
if (li[i] === f)
li.splice(i, 1);
}
}
} else if (o.removeEventListener)
o.removeEventListener(n, f, false);
else
o['on' + n] = null;
}
};
})();
function addListeners() {
var f;
EventUtils.addEvent('elm', 'click', function(e) {
alert('Listener 1: ' + e.target.id);
});
f = EventUtils.addEvent('elm', 'click', function(e) {
alert('Listener 2: ' + e.target.id);
});
EventUtils.addEvent('elm', 'click', function(e) {
alert('Listener 3: ' + e.target.id);
});
EventUtils.removeEvent('elm', 'click', f);
}

Example of an simple event class not using the unload event

실행 코드