const success = 1, fail = 0 ,pendding = -1;
   function MyPromise(deal){
	  this.status = null
	  this.freeze = null
	  Object.defineProperty(this,'status',{
		  get:function(){
			  // console.log("get")
			  return status;
		  },
		  set:function(newValue){
			  // console.log("set")
			  status = newValue; //通过订阅模式    获取异步执行完成的时机
			  this.then(this.resolveCallback,this.rejectallback)
		  
		  },
		  enumerable : true,
		  configurable : true
	  })
	  console.log(this)
	  this.status = pendding;
	  deal(this.resolve.bind(this),this.reject.bind(this))
	  //使用bind是因为函数作为参数传入函数中 调用者为deal函数  resolve和reject中的 this指向变为window或undefined或者箭头函数获取的this
	  return this
  
   }
   MyPromise.prototype.resolve = function(res) {
   	  if(this.freeze) return
	  console.log(res)
	  console.log(this)
	  this.value = res  //value的赋值必须在状态变更之前   不然执行get函数执行then方法时无法获取value
	  this.freeze = true
	  this.status = success
	  
   };
	MyPromise.prototype.reject = function(err) {
	  if(this.freeze) return
	  console.log(err)
	  this.value = err
	  this.freeze = true
	  this.status = fail
			  
   };
	MyPromise.prototype.then = function(resolveCallback,rejectallback) {
	  //将回调函数储存在this上
	   this.resolveCallback = resolveCallback
	   this.rejectallback = rejectallback
	   if(this.status == -1) return this
		  // console.log(this.status+"5656459")
		  // console.log(typeof this.resolveCallback)
		  //此处status为字符串类型 所以不能使用===  为什么是字符串类型暂时未知
		  this.status == 1 && this.resolveCallback && this.resolveCallback(this.value)
		  this.status == 0 && this.rejectallback  && this.rejectallback(this.value)
  
	  // setTimeout(()=>{
	  // 	console.log(this.status+"5656459")
	  // 	// console.log(typeof this.resolveCallback)
  
	  // 	this.status == 1 && this.resolveCallback(this.value)
	  // 	this.status == 0 && rejectallback(this.value)
	  // },0) 
	  return this
   };
   let a =  new MyPromise((resolve)=>{
	  setTimeout(()=>{ //模拟异步操作
		  console.log("454")
		  resolve(78980)
		  resolve(5656)
	  },1000)
	  // new Promise((resolve1)=>{resolve1()}).then(()=>{resolve(456464)})
   })
   // .then(res=>{console.log(res+"45656")})
  //console.log(a.then(res=>{console.log(res+"45656")}).then(res=>{console.log(res+"8888")}))
   // 如果连续.then后面的方法会覆盖之前的方法  储存回调函数应该使用数组然后做相应的处理
	console.log(a.then(res=>{console.log(res+"45656")}))