Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<body>

<form>
<fieldset id="myFieldset" name="personalia">
  Name: <input type="text" name="username"><br>
  Email: <input type="text" name="usermail"><br>
</fieldset>
</form>

<p>Click the button to display the new name of the fieldset.</p>

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

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

<script>
function myFunction() {
    document.getElementById("myFieldset").name = "newName";
    document.getElementById("demo").innerHTML = document.getElementById("myFieldset").name;
}
</script>
</body>
</html>