js倒计时一小时代码

// 设置倒计时的总时间（单位：毫秒）
const totalTime = 60 * 60 * 1000; // 一小时

// 获取显示倒计时的元素
const countdownElement = document.getElementById('countdown');

// 定义一个函数来更新倒计时显示
function updateCountdown() {
  // 计算剩余时间
  const remainingTime = totalTime - (Date.now() - startTime);

  // 如果剩余时间小于等于0，停止倒计时
  if (remainingTime <= 0) {
    clearInterval(intervalId);
    countdownElement.textContent = '倒计时结束';
    return;
  }

  // 计算剩余的小时、分钟和秒
  const hours = Math.floor(remainingTime / (1000 * 60 * 60));
  const minutes = Math.floor((remainingTime % (1000 * 60 * 60)) / (1000 * 60));
  const seconds = Math.floor((remainingTime % (1000 * 60)) / 1000);

  // 更新显示
  countdownElement.textContent = `${hours.toString().padStart(2, '0')}:${minutes.toString().padStart(2, '0')}:${seconds.toString().padStart(2, '0')}`;
}

// 记录开始时间
const startTime = Date.now();

// 每秒更新一次倒计时
const intervalId = setInterval(updateCountdown, 1000);

// 初始化显示
updateCountdown();

// 保存开始时间到localStorage
localStorage.setItem('startTime', Date.now());

// 页面加载时读取开始时间
const startTime = parseInt(localStorage.getItem('startTime'), 10);

function updateCountdown() {
  const now = Date.now();
  const elapsed = now - startTime;
  const remainingTime = totalTime - elapsed;

  if (remainingTime <= 0) {
    clearInterval(intervalId);
    countdownElement.textContent = '倒计时结束';
    return;
  }

  const hours = Math.floor(remainingTime / (1000 * 60 * 60));
  const minutes = Math.floor((remainingTime % (1000 * 60 * 60)) / (1000 * 60));
  const seconds = Math.floor((remainingTime % (1000 * 60)) / 1000);

  countdownElement.textContent = `${hours.toString().padStart(2, '0')}:${minutes.toString().padStart(2, '0')}:${seconds.toString().padStart(2, '0')}`;

  requestAnimationFrame(updateCountdown);
}

requestAnimationFrame(updateCountdown);