<!DOCTYPE html>
<html>
<body>

<p><del id="myDel" datetime="2011-11-15T22:55:03Z">This text has been deleted</del></p>

<p>Click the button to return the value of the datetime attribute of the deleted text.</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<script>
function myFunction() {
    var x = document.getElementById("myDel").dateTime;
    document.getElementById("demo").innerHTML = x;
}
</script>

</body>
</html>