Make the submit button also send an extra value

Question

I have a long form with a submit button that sends the values of all the fields into the address bar.

However, I want the submit button to ALSO add an extra value (&submitted=yes) when it is clicked.

How can I convert my button:

<input type="submit" name="submitted" value="submit">

to do this?

The idea is that I could then use that value in javascript when the page loads along with the other fields:

<script language="javascript">  
var urlParams = new URLSearchParams(window.location.search);
var LastName = urlParams.get('LastName');
var Submitted = urlParams.get('Submitted');

Answer 1

Easiest solution: add a hidden input field to your form.

<input type="hidden" name="submitted" value="yes">