红绿灯 

<!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>红绿灯</title>
  </head>
  <body>
    <script>
      // 使用Promise实现红绿灯交替重复亮
      function red() {
        console.log('red');
      }
      function green() {
        console.log('green');
      }
      function yellow() {
        console.log('yellow');
      }
      const light = function (timer, cb) {
        return new Promise(resolve => {
          setTimeout(() => {
            cb();
            resolve();
          }, timer);
        });
      };

      const step1 = async function () {
        await light(3000, red);
        await light(2000, green);
        await light(1000, yellow);
        await step1();
      };

      step1();
    </script>
  </body>
</html>

 

posted @ 2022-05-04 14:28  苹果π  阅读(20)  评论(0)    收藏  举报