723_promise_API

<script>
      let p = new Promise((resolve, reject) => {
        //同步调用，promise里面的函数会立即执行
        console.log(111);
        //修改promise对象的状态
        reject("err");
      });
      console.log(222);

      //执行catch方法
      p.catch((reason) => {
        console.log(reason);
      });
    </script>