观察者模式

观察者模式具有以下组件

(1) Subject 目标: 维护一系列的观察者,方便添加或者删除观察者

(2) Observer 观察者 : 为那些在目标状态发生改变时需获取得通知的对象提供一个接口

(3) ConcreteSubject 具体目标 : 状态发生改变时,向observer发出通知,储存ConcreteObserver的状态

(4) ConcreteObserver 具体观察者 : 存储一个指向ConcreteSubject的引用,实现Observer的更新

    //----------- observer list
    var ObservertionList = function () {
        this.observerList = [];
    };

    ObservertionList.prototype.add = function (value) {
        this.observerList.push(value);
    };

    ObservertionList.prototype.Get = function (index) {
        //if(){   //do something
        return this.observerList[index];
        //}
    };

    ObservertionList.prototype.Count = function () {
        return this.observerList.length;
    };


    var extend = function (obj, extension) {
        for (var key in obj) {
            extension[key] = obj[key];
        }
    };

    //----------(1) subject

    var Subject = function () {
        this.observers = new ObservertionList();
    };

    Subject.prototype.addObserver = function (obj) {
        this.observers.add(obj);
    };

    Subject.prototype.notify = function (index) {
        //var len = this.observers.Count();
        // for(var i=0;i<len;i++){
        this.observers.Get(index).broadCast();
        // }
    };

    var observations = [
        {
            Id: 1,
            name: "Jackey",
            age: 24,
            skill: function () {
                console.log("programming");
            }
        },
        {
            Id: 2,
            name: "Cassi",
            age: 23,
            skill: function () {
                console.log("cooking");
            }
        }
    ];

    //(2) observer
    var broadCast = function () {
        this.broadCast = function () {
            console.log("broadCast to other");
        };
    };

    var subject = new Subject();
    for (var i = 0; i < observations.length; i++) {
        extend(new broadCast(), observations[i]);
        subject.addObserver(observations[i]);
        subject.notify(i);
    }
    ;