promise 输出 1 2 3 

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>promise 输出 1 2 3</title>
  </head>
  <body>
    <script>
      const arr = [1, 2, 3];
      arr.reduce((p, x) => {
        return p.then(() => {
          return new Promise(r => {
            setTimeout(() => r(console.log(x)), 1000);
          });
        });
      }, Promise.resolve());
    </script>
  </body>
</html>

 

posted @ 2022-05-04 14:27  苹果π  阅读(36)  评论(0)  编辑  收藏  举报