Пример реализации шаблона Pub/Sub

pub_sub.js

var mediator = (function(){
	var subscribe = function(channel, fn){
			if (!mediator.channels[channel]) mediator.channels[channel] = [];
			mediator.channels[channel].push({ context: this, callback: fn });

			return this;
		},
 
	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;
		}
	};
 
}());

Пример использования:

//Pub/sub on a centralized mediator

mediator.name = "tim";
mediator.subscribe('nameChange', function(arg){
    console.log(this.name);
    this.name = arg;
    console.log(this.name);
});

mediator.publish('nameChange', 'david'); //tim, david


//Pub/sub via third party mediator

var obj = { name: 'sam' };
mediator.installTo(obj);
obj.subscribe('nameChange', function(arg){
    console.log(this.name);
    this.name = arg;
    console.log(this.name);
});

obj.publish('nameChange', 'john'); //sam, john