參看書籍JavaScript模式第七章設計模式
我的理解：觀察者模式又叫訂閱／發(fā)布模式崔步。被觀察者（發(fā)布者）內(nèi)部需要有一些東西來處理觀察者（訂閱者）的方法咽扇。
發(fā)布者對象paper 需要有以下這些成員：
1轴猎、subscribers：
??? 一個數(shù)組
//存儲每個事件類型下的訂閱者晴弃。每個類型下訂閱者是一個數(shù)組袱瓮。
2、subscribe()：
??? 將訂閱者添加到subscribers數(shù)組
//訂閱者訂閱某個類型浮禾，傳入對應的回調(diào)函數(shù)交胚。
3、unsubscribe()：
??? 從訂閱者數(shù)組subscribers刪除訂閱者盈电。
4蝴簇、publish():
??? 循環(huán)遍歷subscribers中的每個元素，并且調(diào)用他們注冊時所提供的方法匆帚。
5熬词、visitSubscribers()
??? 遍歷操作訂閱對象的方法。幫助方法卷扮。
如下：
發(fā)布者荡澎；

var publisher = {
    subscribers: {
        any: []           //事件類型：訂閱者
    },
    subscribe: function(fn, type){
        type = type || "any";
        if (typeof this.subscribers[type] === "undefined"){
            this.subscribers[type] = []
        };
        this.subscribers[type].push(fn);
    },
    unsubscribe: function(fn,type){
        this.visitSubscribers('unsubscribe',fn,type);

    },
    publish: function(publication, type){
        this.visitSubscribers('publish',publication,type);

    },
    visitSubscribers: function (action, arg, type){
        var pubtype = type || 'any',
            subscribers = this.subscribers[pubtype],
            i,
            max = subscribers.length;
        for(i = 0;i < max; i += 1){
            if(action === 'publish'){
                subscribers[i](arg);
            }else {
                if (subscribers[i] === arg){
                    subscribers.splice(i, 1);
                }
            }
        }

    }

}

創(chuàng)造一個發(fā)布者均践；

function makePublisher(o){
    var i ;
    for (i in publisher){
        if(publisher.hasOwnProperty(i) && typeof publisher[i] === "function"){
            o[i] = publisher[i];
        }
    }
    o.subscribers = {
        any:[]
    }

}

發(fā)布者對象

var paper = {
    daily:function(){
        this.publish("bing news today");
    },
    monthly: function(){
        this.publish("interesting analysis", "monthly");
    },
    aha: function(){
        this.publish("aha","monday");
    }
};
makePublisher(paper);

訂閱者對象

var joe = {
    drinkCoffee: function (paper){
        console.log("Just read" + paper);
    },
    sundayPreNap: function (monthly){
        console.log('About to fall asleep reading this'+ monthly);
    }
};

發(fā)布事件 和結果

paper.subscribe(joe.drinkCoffee);
paper.subscribe(joe.sundayPreNap, 'monthly');
paper.subscribe(joe.sundayPreNap, 'monday');


paper.daily();//Just readbing news today
paper.daily();//Just readbing news today
paper.daily();//Just readbing news today
paper.monthly();//About to fall asleep reading thisinteresting analysis
paper.aha();//About to fall asleep reading thisaha