Inyección de logica de eventos en objetos

utils.eventize.js

/**
 * Eventiza el objeto, agregandole los 
 * metodos
 *		on
 *		emit
 *		removeListener
 *
 * @param {Object}
 * @return {Object}
 */
var eventize = (function() {
	// Los metodos son unicos y se comparten
	// entre todos los objetos donde se aplique
	// la funcion
	var on, emit, removeListener;
	
	/**
	 * @param {String} event
	 * @param {Function} handler
	 * @param {Object} scope
	 * @return {Object}
	 */
	on = function(event, handler, scope) {
		var handlers = this.__handlers = this.__handlers || {};		
		handlers[event] = handlers[event] || [];		
		handlers[event].push([handler, scope]);
		
		return this;
	};
	
	/**
	 * @param {String} event
	 * @param {...mixed} arguments
	 * @return {Object}
	 */	
	emit = function(event) {
		var
			handlers = (this.__handlers = this.__handlers || {})[event],
			args = Array.prototype.slice.call(arguments, 1);	
		
		if(!handlers) {
			return this;
		}
		
		for(var i = 0, l = handlers.length; i < l; i++) {
			(function(fn, scope) {
				fn.apply(scope, args);
			})(handlers[i][0], handlers[i][1]);
		}
		
		return this;
	};
	
	/**
	 * @param {String} event
	 * @param {Function} handler
	 * @return {Object}
	 */	
	removeListener = function(event, handler) {
		if(!this.__handlers) {
			return this;
		}
	
		if(!handler) {
			delete this.__handlers[event];
			return this;
		}
		
		for(var i = 0, l = this.__handlers[event].length; i < l; i++) {
			if(this.__handlers[event][i][0] === handler) {
				this.__handlers[event].splice(i, 1);
			}
		}
		
		return this;
	};
	
	return function(obj) {
		obj.on = on;
		obj.emit = emit;
		obj.removeListener = removeListener;
		
		return obj;
	};
})();

// Uso

var myObject = {};

// Magic!
eventize(myObject);	

// attach
myObject.on('foo', console.log);
// trigger
myObject.emit('foo', 1, 2, 'bar', {a:'b'}); // 1 2 bar Object { a="b"}
// detach
myObject.removeListener('foo', console.log);
// trigger
myObject.emit('foo', 1, 2, 'bar', {a:'b'}); // ...