js三天倒计时

// 设置目标时间（三天后的时间）
const targetDate = new Date();
targetDate.setDate(targetDate.getDate() + 3);

function updateCountdown() {
  const now = new Date();
  const diff = targetDate - now;

  if (diff <= 0) {
    clearInterval(intervalId);
    document.getElementById('countdown').innerHTML = "倒计时结束";
    return;
  }

  const days = Math.floor(diff / (1000 * 60 * 60 * 24));
  const hours = Math.floor((diff % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  const minutes = Math.floor((diff % (1000 * 60 * 60)) / (1000 * 60));
  const seconds = Math.floor((diff % (1000 * 60)) / 1000);

  document.getElementById('countdown').innerHTML = `${days}天 ${hours}小时 ${minutes}分钟 ${seconds}秒`;
}

const intervalId = setInterval(updateCountdown, 1000);

<div id="countdown"></div>