javascript publish/subscribe or observer pattern

 定义

定义一对多的对象封装，目标对象状态发生变化，它所有的接受者都会收到通知并做相应的更新。

使用频率：5/5 最高

概要

观察者模式，也就是发布者/订阅者模式，当发布者发布一个通知的时候，订阅者就会收到通知，并调用自己的更新方法，做些什么事情。这种通知是单向的，只能由发布者向订阅者发布通知。

图标说明

示例代码

      var Publisher = function () { 

        this.subscribers = [];

      }



      Publisher.prototype = { 



          constructor: Publisher,



          addSubscriber: function(subscriber){ 

            this.subscribers.push(subscriber);

          },



          removeSubscriber: function(subscriber){ 

            var subscribers = this.subscribers,

              len = subscribers.length,

              i = 0;

            for(; i < len; i++){ 

              if (subscribers[i] === subscriber) { 

                delete subscribers[i];

                break;

              };

            }

          },



          notifySubscriber: function(message){ 

            var subscribers = this.subscribers,

              len = subscribers.length,

              i = 0;

            for(; i< len; i++){ 

              subscribers[i].receiveMessage(message);

            }

          }

      };



      var Subscriber = function(subscriberName, publisher){ 

        this.name = subscriberName;

        this.publisher = publisher;

      };



      Subscriber.prototype = { 



        constructor: Subscriber,



        receiveMessage: function(message){ 

          console.log('I am ' + this.name + ' I receive: ' + message);

        }

      };



      var publisher = new Publisher();

      var subUser_001 = new Subscriber('subUser_001', publisher);

      var subUser_002 = new Subscriber('subUser_002', publisher);

      var subUser_003 = new Subscriber('subUser_003', publisher);



      publisher.addSubscriber(subUser_001);

      publisher.addSubscriber(subUser_002);

      publisher.addSubscriber(subUser_003);



      publisher.notifySubscriber('百度推送新闻了');