Tryit Editor v2.7

Edit This Code:

<!DOCTYPE html>
<html>
<body>

<p id="myP">This is a paragraph.</p>

<button type="button" onclick="myFunction()">Set font size</button>
 
<script>
function myFunction() {
    document.getElementById("myP").style.fontSize = "xx-large";
}
</script>

</body>
</html>