<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css"> <script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script> <script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script> <!------ Include the above in your HEAD tag ----------> <script type="text/javascript"> var check = null; function printDuration() { if (check == null) { var cnt = 0; check = setInterval(function () { cnt += 1; document.getElementById("para").innerHTML = cnt; }, 1000); } } function stop() { clearInterval(check); check = null; document.getElementById("para").innerHTML = '0'; } </script> <div> <p id="para">0</p> <input id="btnStart" type="button" value="Start" onclick="printDuration();" /> <input id="btnStop" type="button" value="Stop" onclick="stop();" /> </div>