javascript之观察者模式

demo1:

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));
//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();
}());

　　demo2:

function Observer() {
    this.fns = [];
}
Observer.prototype = {
    subscribe: function (fn) {
        this.fns.push(fn);
    },
    unsubscribe: function (fn) {
        this.fns = this.fns.filter(
                        function (el) {
                            if (el !== fn) {
                                return el;
                            }
                        }
                    );
    },
    update: function (o, thisObj) {
        var scope = thisObj || window;
        this.fns.forEach(
                        function (el) {
                            el.call(scope, o);
                        }
                    );
    }
};

//测试
var o = new Observer;
var f1 = function (data) {
    console.log('Robbin: ' + data + ', 赶紧干活了！');
};

var f2 = function (data) {
    console.log('Randall: ' + data + ', 找他加点工资去！');
};

o.subscribe(f1);
o.subscribe(f2);

o.update("Tom回来了！")

//退订f1
o.unsubscribe(f1);
//再来验证
o.update("Tom回来了！");

　　

if (!Array.prototype.forEach) {
    Array.prototype.forEach = function (fn, thisObj) {
        var scope = thisObj || window;
        for (var i = 0, j = this.length; i < j; ++i) {
            fn.call(scope, this[i], i, this);
        }
    };
}
if (!Array.prototype.filter) {
    Array.prototype.filter = function (fn, thisObj) {
        var scope = thisObj || window;
        var a = [];
        for (var i = 0, j = this.length; i < j; ++i) {
            if (!fn.call(scope, this[i], i, this)) {
                continue;
            }
            a.push(this[i]);
        }
        return a;
    };
}

　　demo3:

//通用代码
var observer = {
    //订阅
    addSubscriber: function (callback) {
        this.subscribers[this.subscribers.length] = callback;
    },
    //退订
    removeSubscriber: function (callback) {
        for (var i = 0; i < this.subscribers.length; i++) {
            if (this.subscribers[i] === callback) {
                delete (this.subscribers[i]);
            }
        }
    },
    //发布
    publish: function (what) {
        for (var i = 0; i < this.subscribers.length; i++) {
            if (typeof this.subscribers[i] === 'function') {
                this.subscribers[i](what);
            }
        }
    },
    // 将对象o具有观察者功能
    make: function (o) { 
        for (var i in this) {
            o[i] = this[i];
            o.subscribers = [];
        }
    }
};
var blogger = {
    recommend: function (id) {
        var msg = 'dudu 推荐了的帖子:' + id;
        this.publish(msg);
    }
};

var user = {
    vote: function (id) {
        var msg = '有人投票了!ID=' + id;
        this.publish(msg);
    }
};

observer.make(blogger);
observer.make(user);
var tom = {
    read: function (what) {
        console.log('Tom看到了如下信息：' + what)
    }
};

var mm = {
    show: function (what) {
        console.log('mm看到了如下信息：' + what)
    }
};
// 订阅
blogger.addSubscriber(tom.read);
blogger.addSubscriber(mm.show);
blogger.recommend(123); //调用发布

//退订
blogger.removeSubscriber(mm.show);
blogger.recommend(456); //调用发布

//另外一个对象的订阅
user.addSubscriber(mm.show);
user.vote(789); //调用发布

　　参考地址：1 http://www.cnblogs.com/rentj1/archive/2013/01/08/2851383.html

2 http://www.cnblogs.com/TomXu/archive/2012/03/02/2355128.html