观察者模式的Javascript实现方式

观察者模式也被称作发布/订阅模式，下面是JAVASCRIPT的一种实现方式

var global = window;

(function(ns, base){
	
	//被观察的对象
	function Observable(){
		
		this.observers = {};
	}	
	
	Observable.prototype = {
		
		//subscribe
		bind: function(name, observer){
			var observers = this.observers[name] || ( this.observers[name] = [] );
			var isbind = observer && observers.indexOf(observer) === -1;
			
			if(isbind){
				observers.push(observer);
			}

		},
		
		//unsubscribe
		unbind: function(name, observer){
			var observers = this.observers[name],
				index = observers && observers.indexOf(observer),
				isunbind = (index !== undefined) && (index > -1);
				
			if (isunbind ){
				observers.splice(index, 1);
			}
		},
		
		//publish
		trigger: function (name, args){
			var observers = this.observers[name];
			if(!observers) return;
			
			for (var i=0; i<observers.length; i++) {
				observers[i](args);
			}
		}
	};
	
	Observable.fn = Observable.prototype;
	ns.Observable = Observable;
	
}(global, undefined));

使用示例：

//测试,Model和View解耦
(function(){

	//UserModel，继承Observable
	function UserModel (id){
		this.id = id;
	}
	
	UserModel.prototype =  new Observable(); 
	
	UserModel.prototype.load = function(){
		//ajax load
		var mode = { name: "jser", id: this.id };
		
		//触发loaded事件
		this.trigger("loaded", { target: this, data: mode } );
	
	}
	
	function UserView(){
		this.render = function(data){
			alert("username: "+ data.name);
		}
	}
	
	var user = new UserModel();
	var view = new UserView();
	
	//添加观察者，当UserMode加载完成调用
	user.bind("loaded", function(event){
		view.render(event.data);
	});
	user.load();
}());