[JS] Wzorzec observer

console.clear();
var cl = function(text){ console.log(text); }

var Users = {
	list: [],
	listeners: {},

	add: function(name) {
		this.list.push({name: name});
		this.dispatch("user-added");
	},
	on: function(eventName, listener) {
		if(!this.listeners[eventName]) this.listeners[eventName] = [];
		this.listeners[eventName].push(listener);
	},
	dispatch: function(eventName) {
		if (this.listeners[eventName]) {
			var i, max = this.listeners[eventName].length;
			for (i = 0; i < max; ++i){
				this.listeners[eventName][i](this);
			}
		}
	},
	numOfAddedUsers: function() {
		return this.list.length;
	}
}

Users.on(
	"user-added",
	function(){
		cl(Users.numOfAddedUsers());
	}
);

Users.add("Casimir");
Users.add("Zygmunt");