promise race 

<!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.race</title>
  </head>
  <body>
    <script>
      const sleep = seconds => new Promise(resolve => setTimeout(() => resolve(seconds), seconds));
    </script>
    <script>
      function promiseRace(_promises) {
        return new Promise((resolve, reject) => {
          const promises = [..._promises];
          const arr = [];
          for (let i = 0; i < promises.length; i++) {
            Promise.resolve(promises[i])
              .then(data => {
                resolve(data);
              })
              .catch(err => {
                reject(err);
              });
          }
        });
      }
      promiseRace([1, 2, 3])
        .then(data => {
          console.log(data);
        })
        .catch(err => {
          console.log(err);
        });

      // all 一个任务失败全是失败，所有成功才算成功
      // any 一个成功就成功，所有失败才失败
      // race 返回最先完成的那个任务
      // allsettled 返回所有任务完成的状态和值
    </script>
  </body>
</html>

 

posted @ 2022-05-04 14:26  苹果π  阅读(21)  评论(0)    收藏  举报