<!DOCTYPE html>
<html>
<body>
<p>Click the button to create a LEGEND element with some text.</p>
<fieldset id="myFieldset">
Name: <input type="text">
</fieldset><br>
<button onclick="myFunction()">Try it</button>
<script>
function myFunction() {
var x = document.createElement("LEGEND");
var t = document.createTextNode("Personalia:");
x.appendChild(t);
document.getElementById("myFieldset").appendChild(x);
}
</script>
</body>
</html>