<!DOCTYPE html>
<html>
<body>
<p>Click the button to display the time.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function addZero(x,n) {
while (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>