Tryit Editor v2.9

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

<form id="myForm">
  <fieldset id="myFieldset">
    <legend>Personalia:</legend>
    Name: <input type="text"><br>
    Email: <input type="text"><br>
    Date of birth: <input type="text">
  </fieldset>
</form>

<p>Click the button to display the id of the form the fieldset belongs to.</p>

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

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

<script>
function myFunction() {
    var x = document.getElementById("myFieldset").form.id;
    document.getElementById("demo").innerHTML = x;
}
</script>
</body>
</html>