title: Html form: easiest way to define value of control based on other controls on client side
body: <p>I want to send the age instead of year born from the form to the server when the submit button is clicked. What is the easiest way to achieve it?</p>
  
  <pre><code>&lt;form action="process.php"&gt;
      &lt;input type="text" name="yearBorn"&gt;
      &lt;input type="hidden" name="Age"&gt;
      &lt;input type="submit" &gt;
  &lt;/form&gt;
  </code></pre>