Added CSRF token to AJAX calls using Form Serialization

ajax_csrf.html

<!-- create form with open_form() -->
<form action="http://testapplication.com/login" method="post" accept-charset="utf-8" id="login-form" class="login">
  <div style="display:none">
    <input type="hidden" name="csrf_test_name" value="80bfb80b356d6d31f4ce4dad0c6cf69e">
  </div>
  ...
  ...
</form>

<!-- Update AJAX code to post serialized data -->
<script type="text/javascript">
$.post( ajax_url, $('#login-form').serialize(), function( response ) {
    // response
}, 'json' );
</script>