<!DOCTYPE html>
<html>
<body>

<p>Click the button to create an I element with some text.</p>

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

<script>
function myFunction() {
    var x = document.createElement("I");
    var t = document.createTextNode("Some italic text");
    x.appendChild(t);
    document.body.appendChild(x);
}
</script>

</body>
</html>