This is Demo for the PubSub design pattern

pubSubDemo.js

/*PubSub Pattern*/

var pubSub = {
    events: [],
    on: function(eventName, fn) {
        this.events[eventName] = this.events[eventName] || [];
        this.events[eventName].push(fn);
    },
    emit:  function(eventName, data) {
        if(this.events[eventName]) {
            this.events[eventName].forEach(function(fn){
                fn(data);
            });
        }
    },
    off: function(eventName, fn) {
        var index = this.events[eventName].indexOf(fn);
        if(index != -1) {
            this.events[eventName].splice(index, 1);
        }
    },
    inspect:function(){
        console.log(this.events);
    }
};

var membersObj = (function(){

	var members = ["Happy"];

	function addMember(name){
		members.push(name);
		pubSub.emit("membersUpdated", members);
	}

	function removeMember(id){
		members.splice(id,1);
		pubSub.emit("membersUpdated", members);
	}

	function inspect (){
		console.log(members);
	}

	return {
		addMember: addMember,
		cutMember: removeMember
	};
})();

var memberActor = (function(){

    function responder(data) {
        console.log("_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-");
        console.log(data);
        console.log("_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-");
    }

    pubSub.on("membersUpdated", responder);

    return {
        off: function(){
            pubSub.off("membersUpdated", responder);
        }
    }
    
})();

//Demo How it get execute.
membersObj.addMember("Harry");
membersObj.cutMember(1);
membersObj.addMember("Darry");

memberActor.off(); // remove the event listner


membersObj.addMember("Sharry"); // nothing will get printed from memberActor