JavaScript 动态显示当前时间的完整示例

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>www.jb51.net JS动态显示时间</title>
  <script>
    var timer=null;
    function displayClock(num){//num是传入的startClock中的动态值
      if(num<10){
        return "0"+num;
      }
      else{
        return num;
      }
    }
    //停止计时
    function stopClock(){
      clearTimeout(timer);
    }
    //开始计时
    function startClock(){
      var time =new Date();
      var hours=displayClock(time.getHours())+":";
      var minutes=displayClock(time.getMinutes())+":";
      var seconds=displayClock(time.getSeconds());
      //显示时间
      show.innerHTML=hours+minutes+seconds;//在id为show的块区域显示
      timer=setTimeout("startClock()",1000);//延时器
    }
  </script>
</head>
<style>
  #show{
    font-size: 24px;
    color:#4213C9;
    text-align:center;
  }
  </style>
<body onload="startClock()" onunload="stopClock()">
  <div id="show"></div>
</body>
</html>