main.js

// Full credit for this example goes to Stoyan Stefanov and his
// amazing book JavaScript Patterns
// http://www.amazon.com/JavaScript-Patterns-Stoyan-Stefanov/dp/0596806752

"use strict";

var publisher = {
	subscribers: {
		any: [] // event type: subscribers
	},
	on: function(type, fn, context) {
		type = type || 'any';
		fn = typeof fn === 'function' ? fn : context[fn];
		if (typeof this.subscribers[type] === "undefined") {
			this.subscribers[type] = [];
		}
		this.subscribers[type].push({ fn: fn, context: context || this });
	},
	remove: function(type, fn, context) {
		this.visitSubscribers('unsubscribe', type, fn, context);
	},
	fire: function(type, publication) {
		this.visitSubscribers('publish', type, publication);
	},
	visitSubscribers: function(action, type, arg, context) {
		var pubtype = type || 'any',
			subscribers = this.subscribers[pubtype],
			i,
			max = subscribers ? subscribers.length : 0;

		for (i = 0; i < max; i += 1) {
			if (action === 'publish') {
				// Call our observers, passing along arguments
				 subscribers[i].fn.call(subscribers[i].context, arg);
			} else {
				if (subscribers[i].fn === arg && subscribers[i].context === context) {
					subscribers.splice(i, 1);
				}
			}
		}
	}
};