<!DOCTYPE html>
<html>

<head>
  <title>Web秀 - 让你的技术真正秀起来</title>
  <meta name="name" content="Javan" />
  <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>