promise-onreject

gistfile1.txt

let doWorkPromise = function (job, timer, success) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      let dt = new Date();
      if (success) {
        // 成功
        return resolve(`完成工作: ${job} at ${dt.toISOString()}`);
      }
      reject(`!!工作失敗: ${job} at ${dt.toISOString()}`);
    }, timer);
  });
};

// 刷完牙 > 吃早餐 > 寫功課

// 作法1
doWorkPromise("刷牙", 2000, true)
  .then((result) => {
    // fulfilled 處理成功 resolve
    console.log(result);
    return doWorkPromise("吃早餐", 3000, false);
  })
  .then((result) => {
    console.log(result);
    return doWorkPromise("寫功課", 5000, true);
  })
  .then((result) => {
    console.log(result);
  })
  .catch((err) => {
    // rejected 處理失敗 reject
    console.error("發生錯誤", err);
  })
  .finally(() => {
    console.log("我是 Finally");
  });
  
// 作法2
doWorkPromise("刷牙", 2000, true)
  .then(
    (result) => {
      // fulfilled 處理成功 resolve
      console.log(result);
      return doWorkPromise("吃早餐", 3000, false);
    },
    (reject) => {
      console.log("中途攔截A", reject);
    }
  )
  .then(
    (result) => {
      console.log(result);
      return doWorkPromise("寫功課", 5000, true);
    },
    (reject) => {
      console.log("中途攔截B", reject);
      // 試試看這行有註解 跟 沒註解的差異
      // return doWorkPromise("寫功課", 5000, true);
    }
  )
  .then(
    (result) => {
      console.log(result);
    },
    (reject) => {
      console.log("中途攔截C", reject);
    }
  )
  .catch((err) => {
    // rejected 處理失敗 reject
    console.error("發生錯誤", err);
  })
  .finally(() => {
    console.log("我是 Finally");
  });