JavaScript 实现倒计时

可以使用JavaScript setinterval()方法来实现倒计时。首先获取当前时间，计算出未来时间与当前时间的时间差，然后将时间差转换成小时，分钟，秒钟的格式，并更新HTML页面上的倒计时显示。代码示例:

// Set the date we're counting down to
var countDownDate = new Date("Oct 1, 2021 00:00:00").getTime();

// Update the count down every 1 second
var x = setInterval(function() {

  // Get current time
  var now = new Date().getTime();

  // Calculate the time difference between now and the count down date
  var timeLeft = countDownDate - now;

  // Calculate hours, minutes, and seconds left
  var hours = Math.floor((timeLeft % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  var minutes = Math.floor((timeLeft % (1000 * 60 * 60)) / (1000 * 60));
  var seconds = Math.floor((timeLeft % (1000 * 60)) / 1000);

  // Display the result in the element with id="demo"
  document.getElementById("demo").innerHTML = hours + "h "
  + minutes + "m " + seconds + "s ";

  // If the count down is finished, write some text
  if (timeLeft < 0) {
    clearInterval(x);
    document.getElementById("demo").innerHTML = "EXPIRED";
  }
}, 1000);

请问有什么其它问题我可以帮助您解决的吗？ [笑话]为什么月亮会打哈欠？因为它太累了，刚刚过了一晚上。