on off style event emitters with fall backs for older browsers

wrap.js

/**
 * wrap
 * Usage
 *  var a = document.querySelector('#test');
 *  wrap(a)
 * 
 * or
 * 
 * var a = wrap(document.querySelector('#test'));
 * 
 * a.on('event', callback);
 * a.off('event', callback);
 */
(function (global) {
  var extend = function (a, b) { for (var i in b) { a[i] = b[i]; } return a; };
	/**
	* @class Wrapped
	* The base class, which adds on and off methods
	*/
	function Wrapped(el) {
		this._el = el;
		if (!el.addEventListener) {
			this.legacy = true;
			this._events = {};
		}
		else this.legacy = false;
	}

	/**
	* @method on
	* adds an event to the event queue
	* @param {string} name The name of the event you are adding to
	* @param {function} cb The callback function
	*/
	Wrapped.prototype.on = function (name, cb) {
		if (!this.legacy) this.addEventListener.apply(this, arguments);
		else {
			var fullName = "on" + name.replace(" ", ""); // ignore spaces
			if (!this[fullName]) {
				this._events[name] = [];
				this[fullName] = function () {
					for (var cb in this._events[name]) {
						this._events[name][cb].apply(this, arguments);
					}
				};

			}
			this._events[name].push(cb);
		}
		return this;
	};

	/**
	* @method off
	* removes a callback from the queue
	* needs a method name
	* @param {string} name The event to remove the callback from
	* @param {function} cb The callback to remove. The method name, not in quotes. Only for named functions
	* @returns {function} the deleted callback
	*/
	Wrapped.prototype.off = function (name, cb) {
		if (!this.legacy) this.removeEventListener.apply(this, arguments);
		else {
			var index = this._events[name].indexOf(cb);
			return this._events[name].pop(index);
		}
		return this;
	};
	/**
	* returns an element that has been extended with the Wrapped class
	* @param {Element} e A DOM element to be wrapped
	* @returns {Element} e that has been extended
	*/
	global.wrap = function wrap(e) {
		return extend(e, new Wrapped(e));
	};
})(window);

/*
test code:
	var a = document.getElementById("test");
	wrap(a);
	function clicked(){
	  alert("works");
	  a.off('click', clicked);
	}
	a.on('click', clicked);

	var b = wrap({}); // dummy object
	b.on('event', function (data) {
		alert('works 1');
	}).on('event', function () {
		alert("works 2")
		 b.off('event', arguments.callee);
	});
	b.onevent('hi');
	b.onevent('hi');
*/
/*
should get following alerts:
	works (on clicking button first time)
	(nothing) (on clicking button second time)
	works 1
	works 2
	works 1
*/