promise异步获取数据

let promise2 = new Promise((resolve, reject) => {
      if (this.status === RESOLVED) {
        setTimeout(() => {
          try {
            let x = onFulfilled(this.value);
            resolvePromise(promise2, x, resolve, reject);
          } catch (e) {
            reject(e);
          }
        }, 0);
      }

注意要拿到promise2得用异步方法，然后异步方法捕获不到错误