JavaScript: Pub/Sub Mediator Pattern

mediator.js

window.mediator = (function(){
	var subscribe = function(channel, fn, _context){
		_context = (typeof _context != 'undefined') ? _context : this;
		if (!mediator.channels[channel]) mediator.channels[channel] = [];
		mediator.channels[channel].push({ context: _context, callback: fn });
		return _context;
	},
	publish = function(channel){
		if (!mediator.channels[channel]) return false;
		var args = Array.prototype.slice.call(arguments, 1);
		for (var i = 0, l = mediator.channels[channel].length; i < l; i++) {
			var subscription = mediator.channels[channel][i];
			subscription.callback.apply(subscription.context, args);
		}
		return this;
	};
	return {
		channels: {},
		publish: publish,
		subscribe: subscribe,
		installTo: function(obj){
			obj.subscribe = subscribe;
			obj.publish = publish;
		}
	};

}());