const fetchData = () => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      const success = true;
      if (success) {
        resolve("数据获取成功");
      } else {
        reject("请求失败");
      }
    }, 1000);
  });
};

fetchData()
  .then(data => console.log(data))
  .catch(error => console.error(error));

fetchData()
  .then(step1)
  .then(step2)
  .then(step3)
  .catch(err => console.log("出错啦：", err));

const handleData = async () => {
  try {
    const result1 = await fetchData();
    console.log(result1);

    const result2 = await anotherAsyncTask();
    console.log(result2);
  } catch (error) {
    console.error("捕获异常：", error);
  }
};

// 模拟一个API请求
const apiCall = (url) => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      if (url) {
        resolve({ code: 200, data: `来自${url}的数据` });
      } else {
        reject({ code: 500, message: "URL不能为空" });
      }
    }, 800);
  });
};

// 使用async/await调用
const getData = async () => {
  try {
    const res = await apiCall("/users");
    console.log(res.data);
  } catch (err) {
    console.error("请求出错：", err.message);
  }
};

const parallelTasks = async () => {
  try {
    const [res1, res2] = await Promise.all([
      apiCall("/users"),
      apiCall("/posts")
    ]);
    console.log(res1.data, res2.data);
  } catch (error) {
    console.error("任一请求失败即触发catch");
  }
};

const [res1, res2] = await Promise.all([
  apiCall("/users").catch(err => err),
  apiCall("/wrong").catch(err => err)
]);