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  /*-------------------------------------------------------------------
     *
     * TRACK SOURCE WITH A COOKIE
     * This will check if the query and save its values into a cookie for 180 days and will only be removed if they clear their cookies or if they visit via another source query
     * ex. http://rmcad.edu/event/rmcad-create-day-0?utm_source=Social&utm_medium=Twitter&utm_campaign=CreateDay2.15
     * utm_source = Social
     * utm_medium = Twitter
     * utm_campaign = CreateDay2.15
     *
  -------------------------------------------------------------------*/    
	if (sourcecode = $.parseQuery().utm_source) {
		$.cookie("lead_source_form", sourcecode, { expires: 180, path: '/' });
	}
	$(".utm_source").val($.cookie("lead_source_form"));
	if (mediumcode = $.parseQuery().utm_medium) {
		$.cookie("lead_medium_form", mediumcode, { expires: 180, path: '/' });
	}
	$(".utm_medium").val($.cookie("lead_medium_form"));
	if (campaigncode = $.parseQuery().utm_campaign) {
		$.cookie("lead_campaign_form", campaigncode, { expires: 180, path: '/' });
	}
	$(".utm_campaign").val($.cookie("lead_campaign_form"));

<!-- include these additional plugins -->
<script type="text/javascript" src="../js/jquery.cookie.js"></script>
<script type="text/javascript" src="../js/jquery.parsequery.min.js"></script>

<form>
  <!-- rest of form elements -->
  <input class="utm_source" name="utm_source" type="hidden" value="" />
  <input class="utm_medium" name="utm_medium" type="hidden" value="" />
  <input class="utm_campaign" name="utm_campaign" type="hidden" value="" />
</form>

<?php 
function fromCookie($key) {
 $value = isset($_GET[$key]) ? $_GET[$key] : ""
  if (!isset($_SESSION[$key] && $value) {
    $_SESSION[$key] = $value;
  }  
  return $value;
}
?>

<form>
  <!-- rest of form elements -->
  <input class="utm_source" name="utm_source" type="hidden" value="<?php echo fromCookie("utm_source"); ?>" />
  <input class="utm_medium" name="utm_medium" type="hidden" value="<?php echo fromCookie("utm_medium"); ?>" />
  <input class="utm_campaign" name="utm_campaign" type="hidden" value="<?php echo fromCookie("utm_campaign"); ?>" />
</form>