JavaScript 实现数字翻转倒计时效果

<!--倒计时-->
<!DOCTYPE html>
<html>

<head>
 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
 <style>
  #numbers p {
   position: absolute;
   font-size: 100px;
   left: 50%;
   top: 30%;
   margin-left: -29px;
   display:none;
  }
 </style>
</head>

<body>
 <div id="numbers">
  <p>3</p>
  <p>2</p>
  <p>1</p>
 </div>
</body>

</html>

<script type="text/javascript">
  window.onload = function () {
   var numbers = document.getElementById('numbers');
   var number = numbers.getElementsByTagName('p');
   var i = 0;
   number[i].style.display = 'block';
   i = 1;
   timer = setInterval(function () {
    if (i != number.length) {
     number[i - 1].style.display = 'none';
     number[i].style.display = 'block';
    } else {
     number[i - 1].style.display = 'none';
     clearInterval(timer);
    }
    i++;
   }, 1000)
  }
</script>