723_promise_all

<script>
      //
      let p1 = Promise.reject("123");
      let p2 = Promise.resolve(123);
      let p3 = Promise.resolve("qwer");

      let p = new Promise((resolve, reject) => {
        resolve("OK");
      });

      //只有全部成功才会返回成功结果，且成功结果为成功的Promise数组
      //只要有一个不成功就会返回失败，失败结果为失败的那个Promise对象

      const result = Promise.all([p1, p2, p3, p]);
      console.log(result);
    </script>