// 傳入需要倒計時的秒數
    countDown(times) {
      // 時間間隔 1秒
      const interval = 1000;
      // 計算時間，轉化為毫秒
      let ms = times * 1000;
      let count = 0;
      const startTime = new Date().getTime();
      const endTime = startTime + ms;
      let timeCounter;
      timeCounter = setTimeout(countDownStart,
 
 interval)
      function countDownStart() {
        count++
        const offset = new Date().getTime() - (startTime + count * interval);
        // 計算剩餘時間
        const diff = endTime - new Date().getTime();
        const h = Math.floor(diff / (60 * 1000 * 60));
        const hdiff = diff % (60 * 1000 * 60);
        const
 
 m = Math.floor(hdiff / (60 * 1000));
        const mdiff = hdiff % (60 * 1000);
        const s = mdiff / (1000);
        const sCeil = Math.ceil(s);
        const sFloor = Math.floor(s);
        let nextTime = interval - offset;
        if (nextTime < 0) {
          nextTime = 0
        }
        ms = ms - interval;
 

        console.log(`誤差：${offset} ms，下一次執行：${nextTime} ms 後，離活動開始還有：${ms} ms`);
        console.log('時：' + h, '分：' + m, '毫秒：' + s, '秒向上取整：' + sCeil)
        if (ms < 0) {
          clearTimeout(timeCounter)
          console.log('此處執行自己想要的操作')
        } else {
          timeCounter = setTimeout(countDownStart, nextTime)
        }
      }
    }

核心程式碼如上，可以更具自己的業務邏輯修改