JS实现观察者模式

观察者模式 又称 订阅发布模式

QQ Email 客户端订阅消息 从报社发布消息，然后客户d端接收。

代码如下：

            //观察者模式  又称订阅发布模式
            function Newspaper() {
                var list = new Set();
                //订阅
                this.subscribe = function(c) {
                    list.add(c);
                }
                //取消订阅
                this.unsubscribe = function(c) {
                    list.remove();
                }
                //发布新闻
                this.publish = function(msg) {
                    for(var i of list.keys()) {
                        i.notice(msg);
                    }
                }
                //每4s产生一条新闻
                this.start = function() {
                    setInterval(function() {
                        this.publish(Math.random());
                    }.bind(this), 4000);
                }
            }

            function Client() {
                this.notice = function(msg) {
                    console.log(this.type + "内容：" + msg);
                }
            }
            var QQ = function() {
                this.type = "QQ";
            };
            QQ.prototype = new Client();
            var Email = function() {
                this.type = "Email";
            };
            Email.prototype = new Client();

            var theme = new Newspaper();
            theme.start();
            theme.subscribe(new QQ("aaa"));
            theme.subscribe(new Email("aaa@qq.com"));