<!DOCTYPE html>
<html>
<body>
<p id="myP" style="text-decoration:line-through;">This is an example paragraph.</p>
<button type="button" onclick="myFunction()">Return text decoration of p</button>
<script>
function myFunction() {
alert(document.getElementById("myP").style.textDecoration);
}
</script>
</body>
</html>