沒(méi)有狀態(tài)

function  fakepromise(fn) {
      var that = this
      function f1() {
          that.arr[0]()
      }
      fn(f1)
      this.arr = []
      this.then = function (fn) {
          this.arr.push(fn)
      }
  }
   var p = new fakepromise(function (resolve,reject) {
       setTimeout(function () {
           console.log('hhh')
           resolve()
       }, 0)
   })
    p.then(function () {
        console.log('我是then函數(shù)里面的')
    })