function Wechat(){        this.state = [];                //    订阅        this.subscribe = function(obj){            this.state.push(obj)        };                //    发布        this.publish = function(){            this.state.forEach(function(v){                v.natice();            })        };                //    取消订阅        this.unsubcribe = function(obj){            this.state.forEach((items,index)=>{                if(items === obj){                    this.state.splice(index,1)                }            })        };    }        var zhangsan = {        'name':'张三',        natice:function(){            console.log(this.name+'收到了新闻')        }    }        var lisi = {        'name':'李四',        natice:function(){            console.log(this.name+'收到了新闻')        }    }        var WechatPublish = new Wechat();    //    张三和李四订阅了    WechatPublish.subscribe(zhangsan)    WechatPublish.subscribe(lisi)        //    微信每隔2秒发布一个新闻给订阅的人        setInterval(function(){        WechatPublish.publish()        console.log(WechatPublish.state)    },2000)        //    6秒后张三实在受不了了，一怒之下取消了订阅    setTimeout(function(){        WechatPublish.unsubcribe(zhangsan)        console.log(WechatPublish.state)    },6000)