723_promise问题_串联多任务

<script>
      let p = new Promise((resolve, reject) => {
        setTimeout(() => {
          resolve("OK");
        }, 1000);
      });

      p.then((value) => {
        return new Promise((resolve, reject) => {
          resolve("success");
        })
          .then((value) => {
            console.log(value); //1秒后输出success
          })
          .then((value) => {
            console.log(value); //undefined
          });
      });
    </script>