JS implements a stopwatch timer

This article example shares the specific code of JS to implement the stopwatch timer for your reference. The specific content is as follows

Implementation of stopwatch timer:

The effect diagram is as follows:

Attached code, debugged and run

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    #div1 {
      width: 300px;
      height: 400px;
      background: skyblue;
      margin: 100px auto;
      text-align: center;
    }
    
    #count {
      width: 200px;
      height: 150px;
      line-height: 150px;
      margin: auto;
      font-size: 40px;
    }
    
    #div1 input {
      width: 150px;
      height: 40px;
      background: orange;
      font-size: 25px;
      margin-top: 20px
    }
  </style>
</head>

<body>
  <div id="div1">
    <div id="count">
      <span id="id_H">00</span>
      <span id="id_M">00</span>
      <span id="id_S">00</span>
    </div>
    <input id="start" type="button" value="Start">
    <input id="pause" type="button" value="Pause">
    <input id="stop" type="button" value="Stop">
  </div>
  <script>
    //You can simplify the operation of finding label nodes var btn = getElementById('btn')
    function $(id) {
      return document.getElementById(id)
    }
    window.onload = function() {
      //Click to start building and counting var count = 0
      var timer = null //The timer variable records the return value of the timer setInterval $("start").onclick = function() {
        timer = setInterval(function() {
          count++;
          console.log(count)
            // Need to change the value of hours, minutes and seconds on the page console.log($("id_S"))
          $("id_S").innerHTML = showNum(count % 60)
          $("id_M").innerHTML = showNum(parseInt(count / 60) % 60)
          $("id_H").innerHTML = showNum(parseInt(count / 60 / 60))
        }, 1000)
      }
      $("pause").onclick = function() {
          //Cancel the timer clearInterval(timer)
        }
        //Stop counting, clear data, and clear page display data$("stop").onclick = function() {
        //Cancel the timer $("pause").onclick()
          // clearInterval(timer)
          //Data clear total seconds clear count = 0
          // Page display data cleared $("id_S").innerHTML = "00"
        $("id_M").innerHTML = "00"
        $("id_H").innerHTML = "00"
      }

      //Encapsulate a function that processes single-digit numbers function showNum(num) {
        if (num < 10) {
          return '0' + num
        }
        return num
      }
    }
  </script>
</body>

</html>

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