AJAX library not added when cart is empty

+++ b/dc_ajax_add_cart.module
@@ -336,10 +336,9 @@ function dc_ajax_add_cart_block_view($delta = '') {
       drupal_add_css(drupal_get_path('module', 'dc_ajax_add_cart') . '/css/dc_ajax_add_cart.css');
       drupal_add_js(drupal_get_path('module', 'dc_ajax_add_cart') . '/js/dc_ajax_add_cart_html.js');

If the cart is empty, do any of these resources need to be added?

I was not able replicate the JS error. The ajax library is required by the "remove from cart" link, and it will only appear if there is some item in the cart.

You are concerned about this part of the module:

      // Hide cart if it is empty.
      if ($hide_empty_cart) {
        $block['content'] = theme('html_tag', array(
          'element' => array(
            '#tag' => 'div',
            '#value' => '',
            '#attributes' => array(
              'class' => 'ajax-shopping-cart-wrapper',
            ),
          ),
        ));
      }
      else {
        $block['content'] = '<div class="ajax-shopping-cart-wrapper">';
        $block['content'] .= theme('dc_ajax_shopping_cart', array(
          'order' => $commerce_cart['order'],
          'line_items' => $line_items,
          'quantity' => $quantity,
          'total' => $total,
        ));
        $block['content'] .= '</div>';

        drupal_add_library('system', 'drupal.ajax', TRUE);
      }

We need drupal_add_library('system', 'drupal.ajax', TRUE); so as to ajaxify the "Remove from cart" link. And this link is only going to appear if there is a product in the cart. And suppose there is a product in cart, then Drupal ajax library is going to be added in the page.

This is a vanilla Drupal + Commerce installation, there is no product in cart, and there are no JS errors.

Please mention the steps so that I can replicate the problem.

+++ b/includes/dc_ajax_add_cart.inc
@@ -9,6 +9,7 @@
+  drupal_add_library('system', 'drupal.ajax', TRUE);
   drupal_add_css(drupal_get_path('module', 'dc_ajax_add_cart') . '/css/dc_ajax_add_cart.css');
   drupal_add_js(drupal_get_path('module', 'dc_ajax_add_cart') . '/js/dc_ajax_add_cart_html.js');

To make this even more of a nitpickery: why not hook_library to have dependency declared there. Then we only need to register the library and we get the CSS, JS and dependencies

https://api.drupal.org/api/drupal/modules%21system%21system.api.php/func...

Any other library that adds drupal.ajax would unintentionally solve this dependency problem.

Yeah true. Thanks for pointing it out. I never thought it this way. I was assuming that the ajax library was added from the block view only. I carried out a test by removing drupal_add_library('system', 'drupal.ajax', TRUE); and still it was functioning. This patch is infact better than the previous one.

The ajax functionalities in the block, and ajaxifying the "Add to Cart" button, all of them needs to be decoupled, but that is not the scope of this issue. I would very much like to decouple them in the 8.x version of this module.

I've opened another issue #2891050: Use hook_library() to add resources which is going to implement Matt's suggestion.

Thank you Joël :)

We have a separate issue for adding hook_library() #2891050: Use hook_library() to add resources