1. function myFetch(timeout) {
    2.   // 通过setTimeount模拟封装fetch
    3.   const fetch = () => {
    4.     return new Promise((resolve, reject) => {
    5.       setTimeout(() => {
    6.         resolve("ok");
    7.       }, 3 * 1000);
    8.     });
    9.   };
    11.   return new Promise((resolve, reject) => {
    12.     // 模拟fetch，运行成功则resolve
    13.     fetch().then(() => {
    14.       resolve("ok");
    15.     });
    16.     // 模拟超时，超时则reject
    17.     setTimeout(() => {
    18.       reject("timeout");
    19.     }, timeout * 1000);
    20.   });
    21. }
    23. myFetch(2)
    24.   .then((v) => {
    25.     console.log(v);
    26.   })
    27.   .catch((e) => {
    28.     console.log(e);
    29.   });