<!DOCTYPE html>
<html>
<body>
<p>Click the button to display the numbers of milliseconds between a specified date and midnight January 1, 1970.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
var d = Date.UTC(2012, 02, 30);
document.getElementById("demo").innerHTML = d;
}
</script>
</body>
</html>