How to Create Stopwatch Using JavaScript

The following example shows, how to create stopwatch using JavaScript.
Demo

Example
<html>
  <head>
    <style>
      @font-face{
       font-family:'digital-font';
       src: url('digital-7.ttf');
      }
      .timer{
        font-family:digital-font;
        font-size:30px;
      }
    </style>
  </head>
  <body>
    <div class='timer'>
      <label id='hour'>00</label>:
      <label id='minute'>00</label>:
      <label id='second'>00</label>
    </div>
    <input type='button' value='Start' id='start'>
    <input type='button' value='Stop' id='stop'>
    <input type='button' value='Reset' id='reset'>
    
    <script>
      var interval;
      document.querySelector("#start").onclick=function(){
        interval=setInterval(timer,1000);
        document.querySelector("#start").disabled=true;
        document.querySelector("#stop").disabled=false;
        document.querySelector("#reset").disabled=false;
      }
      
      document.querySelector("#stop").onclick=function(){
        clearInterval(interval);
        document.querySelector("#start").disabled=false;
        document.querySelector("#stop").disabled=true;
      }
      
      document.querySelector("#reset").onclick=function(){
        document.querySelector("#start").disabled=false;
        document.querySelector("#stop").disabled=true;
        document.querySelector("#reset").disabled=true;
        
        clearInterval(interval);
        document.querySelector("#hour").innerText="00";
        document.querySelector("#minute").innerText="00";
        document.querySelector("#second").innerText="00";
      }
      
      function timer(){
        var hour=document.querySelector("#hour");
        var minute=document.querySelector("#minute");
        var second=document.querySelector("#second");
        
        h=Number(hour.innerText);
        m=Number(minute.innerText);
        s=Number(second.innerText);
        s++;
        if(s>60){
          s=0;
          m++;
        }
        if(m>60){
          m=0;
          h++;
        }
        hour.innerText=formatTime(h);
        minute.innerText=formatTime(m);
        second.innerText=formatTime(s);
      }
      
      function formatTime(x){
        if(x<10){
          return "0"+x;
        }
        return x;
      }
    </script>
  </body>
</html>
Try it Yourself
Others

Others

How to Create Stopwatch Using JavaScript

Demo
