js计时器秒表功能

HTML

 <input type="text" id="timetext" value="00:00:00" readonly>
  <button type="button" onclick="start()">开始button> 
  <button type="button" onclick="stop()">暂停button> 
  <button type="button" onclick="Reset()">重置button>

Script

<script>
    var hour,minute,second;//时 分 秒
    hour=minute=second=0;//初始化
    var millisecond=0;//毫秒
    var int;
    function Reset()//重置
    {
      window.clearInterval(int);
      millisecond=hour=minute=second=0;
      document.getElementById('timetext').value='00:00:00:000';
    }
 
    function start()//开始
    {
      int=setInterval(timer,50);
    }
 
    function timer()//计时
    {
      millisecond=millisecond+50;
      if(millisecond>=1000)
      {
        millisecond=0;
        second=second+1;
      }
      if(second>=60)
      {
        second=0;
        minute=minute+1;
      }
 
      if(minute>=60)
      {
        minute=0;
        hour=hour+1;
      }
      document.getElementById('timetext').value=toDub(hour)+':'+toDub(minute)+':'+toDub(second);
 
    }

    function stop()//暂停
    {
      window.clearInterval(int);
    }
    //补零
    function toDub(n){
        return n<10?"0"+n:""+n;
    }
  </script>

如图：

www.foryh.com

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