设计模式之观察者模式

var pubsub = {};(function (q) {
    var topics = {}, // 回调函数存放的数组        subUid = -1;    // 发布方法    q.publish = function (topic, args) {
        if (!topics[topic]) {            return false;        }
        setTimeout(function () {            var subscribers = topics[topic],                len = subscribers ? subscribers.length : 0;
            while (len--) {                subscribers[len].func(topic, args);            }        }, 0);
        return true;
    };    //订阅方法    q.subscribe = function (topic, func) {
        if (!topics[topic]) {            topics[topic] = [];        }
        var token = (++subUid).toString();        topics[topic].push({            token: token,            func: func        });        return token;    };    //退订方法    q.unsubscribe = function (token) {        for (var m in topics) {            if (topics[m]) {                for (var i = 0, j = topics[m].length; i < j; i++) {                    if (topics[m][i].token === token) {                        topics[m].splice(i, 1);                        return token;                    }                }            }        }        return false;    };} (pubsub));

//来，订阅一个pubsub.subscribe('example1', function (topics, data) {    console.log(topics + ": " + data);});
//发布通知pubsub.publish('example1', 'hello world!');pubsub.publish('example1', ['test', 'a', 'b', 'c']);pubsub.publish('example1', [{ 'color': 'blue' }, { 'text': 'hello'}]);

//将订阅赋值给一个变量，以便退订var testSubscription = pubsub.subscribe('example1', function (topics, data) {    console.log(topics + ": " + data);});
//发布通知pubsub.publish('example1', 'hello world!');pubsub.publish('example1', ['test', 'a', 'b', 'c']);pubsub.publish('example1', [{ 'color': 'blue' }, { 'text': 'hello'}]);
//退订setTimeout(function () {    pubsub.unsubscribe(testSubscription);}, 0);
//再发布一次，验证一下是否还能够输出信息pubsub.publish('example1', 'hello again! (this will fail)');

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f1o.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;    };}

//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

(function ($) {
    var o = $({});
    $.subscribe = function () {        o.on.apply(o, arguments);    };
    $.unsubscribe = function () {        o.off.apply(o, arguments);    };
    $.publish = function () {        o.trigger.apply(o, arguments);    };
} (jQuery));

//回调函数function handle(e, a, b, c) {    // `e`是事件对象，不需要关注    console.log(a + b + c);};
//订阅$.subscribe("/some/topic", handle);//发布$.publish("/some/topic", ["a", "b", "c"]); // 输出abc        
$.unsubscribe("/some/topic", handle); // 退订
//订阅$.subscribe("/some/topic", function (e, a, b, c) {    console.log(a + b + c);});
$.publish("/some/topic", ["a", "b", "c"]); // 输出abc
//退订（退订使用的是/some/topic名称，而不是回调函数哦，和版本一的例子不一样$.unsubscribe("/some/topic");