How can I refer to the shopping cart using document.getElementById if it does not have an id?

You can't. This is where jQuery is your friend: $(".pane-uc-cart-0").val() ...will get the value of the FIRST element with the pane-uc-cart-0 class. jQuery ships with Drupal, and is automatically added whenever there is JavaScript, so you don't need to add the jQuery library using drupal_add_js(). FYI, class names in Drupal are usually added left-to-right, from least-specific to most-specific. So, the last class is the one that is the most specific to that particular element. -Karl.