Tryit Editor v2.9

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

<form id="frm1" action="form_action.asp">
  First name: <input type="text" name="fname" value="Donald"><br>
  Last name: <input type="text" name="lname" value="Duck"><br><br>
  <input type="submit" value="Submit">
</form>

<p>Click "Try it" to display the number of elements the form:</p>

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

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

<script>
function myFunction() {
    var x = document.getElementById("frm1").length;
    document.getElementById("demo").innerHTML = x;
}
</script>

</body>
</html>