PubSub implementation using closures in JavaScript

gistfile1.js

var makePubSub = function () {
	var callbacks = {},
        publish = function (){
            //Turn arguments object into real array
            var args = Array.prototype.slice.call(arguments, 0);
    
            //Extract the event name which is the first entry
            var ev = args.shift();

            //Return if callbacks object doesn't contain 
	    //any entry for event
            var list, i, l;
            if(!callbacks[ev]) { return this; }
            list = callbacks[ev];
    
            //Invoke the callbacks, passing in the rest of parameters
            for (i=0, l=list.length; i<l; i=i+1){
                list[i].apply(this, args);
            }

            return this;
        },
        subscribe = function (ev, callback){
	    //Check if ev is already registered
	    // If it isn't create an array entry for it
            if(!callbacks[ev]){
                callbacks[ev] = [];
            }
            callbacks[ev].push(callback);
            return this;
        };

	return {pub: publish, sub: subscribe};
};

test = makePubSub()
test.sub('alert', function(){alert('hello');})
test.pub('alert')