<html>
<body>
<p id="demo">Click the button to display the time.</p>
<button onclick="myFunction()">Try it</button>
<script>
function addZero(x,n)
{
if (x.toString().length<n)
{
x="0" + x;
}
return x;
}
function myFunction()
{
var d=new Date();
var x=document.getElementById("demo");
var h=addZero(d.getHours(),2);
var m=addZero(d.getMinutes(),2);
var s=addZero(d.getSeconds(),2);
var ms=addZero(d.getMilliseconds(),3);
x.innerHTML=h + ":" + m + ":" + s + ":" + ms;
}
</script>
</body>
</html>