求大神帮我写一个js的计时器，只需要时分秒毫秒，不要倒计时，不要倒计时！！！谢谢[face]emoj

求大神帮我写一个js的计时器，只需要时分秒毫秒，不要倒计时，不要倒计时！！！谢谢[face]emoji:012.png[/face]

<html lang="en">
<head>
      <meta charset="UTF-8">
      <meta name="viewport" content="width=device-width, initial-scale=1.0">
      <title>计时器</title>
      <style>
            html,body{height:100%;width:100%;background-color:rgb(48, 65, 86);}
			.btn{background-color:#409EFF;color:#ddd;padding:3px 7px;border:0;border-radius:5px;letter-spacing:2px;cursor:pointer;}
			#box{height:40px;padding:10px;width:20px;color:#fff;font-size:20px;line-height:40px;}
	  </style>
     
</head>
<body>
      <div id="box">00:00:00:000</div>
	  <div class="control">
			<span class="btn" onclick="setTimer('begin')">开始</span>
			<span class="btn" onclick="setTimer('suspend')">暂停</span>
			<span class="btn" onclick="setTimer('reset')">重置</span>
	  </div>
	   <script>
			let hour=0,minute=0,second=0,millisecond=0;
			let box = document.getElementById('box');
			let Interval;
            function setTimer(e){
				if(e=='begin'){
					Interval=setInterval(timer,50);
				}else if(e=='suspend'){
					 window.clearInterval(Interval);
					
				}else{
                    hour=00;minute=00;second=00;millisecond=00;
				  window.clearInterval(Interval);
				  box.innerHTML = '00:00:00:000';
				}
			}
			
			
			function timer(){
				
					millisecond+=50;
					if(millisecond>=1000)
					  {
						millisecond=0;
						second++;
					  }
					if(second>=60)
					{
						second=0;
						minute++;
					}
			   
					if(minute>=60)
					{
						minute=0;
						hour++;
					}
					if(hour<10){
						hour=PrefixInteger(hour,2);
					}
					if(minute<10){
						minute=PrefixInteger(minute,2);
					}
					if(second<10){
						second=PrefixInteger(second,2);
					}
					
					box.innerHTML=hour+':'+minute+':'+second+':'+millisecond;
				
				
			}
			function PrefixInteger(num, length) {
			 return (Array(length).join('0') + num).slice(-length);
			}
      </script>
</body>
</html>

答案满意记得采纳，谢谢

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>计时器</title>
  <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时00分00秒000毫秒';
    }
   
    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=hour+'时'+minute+'分'+second+'秒'+millisecond+'毫秒';
   
    }
   
    function stop()//暂停
    {
      window.clearInterval(int);
    }
  </script>
</head>
<body>
<div style="text-align: center">
  <input type="text" id="timetext" value="00时00分00秒" readonly><br>
  <button type="button" onclick="start()">开始</button> <button type="button" onclick="stop()">暂停</button> <button type="button" onclick="Reset()">重置</button>
</div>
</body>
</html>