Javascript设计模式之观察者模式的多个实现版本实例

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;
    };
}

//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");