手写promise

class Promise{
  constructor(excutor){
    this.value = '';
    this.reason = '';
    this.status = 'padding'
    this.onFulfilledCallback = []
    this.onRejectedCallback = []
    let resolve = (value)=>{
      /*2.这个判断是为了status不可逆 只能从 padding转化为 成功或者失败*/
      if (this.status == 'padding') {
        this.status = 'fulfilled'
        this.value = value
        /*3.当转态改变的时候依次执行队列里面储存的then函数里面对应的回调*/
        this.onFulfilledCallback.forEach(fn=>{
          fn()
        })
      }
    };
    let reject = (reason)=>{
      /*2.这个判断是为了status不可逆 只能从 padding转化为 成功或者失败*/
      if (this.status == 'padding') {
        this.status = 'rejected'
        this.reason = reason
        /*3.当转态改变的时候依次执行队列里面储存的then函数里面对应的回调*/
        this.onRejectedCallback.forEach(fn=>{
          fn()
        })
      }
    };
    /*1. 当发生异常是捕获异常 */
    try{
      excutor(resolve,reject)
    }catch (e){
      reject(e)
    }

  }
  then(onFulfilled,onRejected){
    //4.防止使用者不传成功或失败回调函数，所以成功失败回调都给了默认回调函数
    onFulfilled = typeof onFulfilled === "function" ? onFulfilled : value => value;
    onRejected = typeof onRejected === "function" ? onRejected : error => { throw error };
    let newPromise;
    if(this.status == 'fulfilled'){
      return newPromise = new Promise((resolve,reject)=>{
        setTimeout(()=>{
          try{
            let x = onFulfilled(this.value)
            this.resolvePromise(newPromise, x, resolve, reject);
          }catch (e){
            reject(e)
          }
        })

      })

    }
    if(this.status == 'rejected'){
      return newPromise = new Promise((resolve,reject)=>{
        setTimeout(()