Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<body>

<p onclick="myFunction(event)">Click this paragraph to get the number of milliseconds since midnight of January 1, 1970.</p>

<p>Timestamp: <span id="demo"></span></p>

<script>
function myFunction(event) {
    var n = event.timeStamp;
    document.getElementById("demo").innerHTML = n;
}
</script>

</body>
</html>