<!DOCTYPE html>
<html>
<body>
<p>Click the button to display the milliseconds of a given date-time.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
var d = new Date("July 21, 1983 01:15:00:526");
var n = d.getMilliseconds();
document.getElementById("demo").innerHTML = n;
}
</script>
</body>
</html>