使用save cart事件后没有得到Ajax响应

Question

Hello All我使用ajax方法为可配置产品添加多个关联产品。我使用了下面的代码，我的代码运行良好，但无法隐藏加载程序并在成功后提醒消息。

的Js代码

<script type="text/javascript">
    var productAddToCartForm = new VarienForm('product_addtocart_form_ext');
    productAddToCartForm.submit = function(button, url) {
            if (this.validator.validate()) {
                var form = this.form;
                var oldUrl = form.action;

                if (url) {
                   form.action = url;
                }
                var e = null;
                //Start of our new ajax code
                if(!url){
                    url = jQuery('#product_addtocart_form_ext').attr('action');
                }
                var data = jQuery('#product_addtocart_form_ext').serialize();

                data += '&isAjax=1';   
                jQuery('#ajax_loader').show();
                try {
                    jQuery.ajax({
                          url: url,
                          dataType: 'json',
                          type : 'post',
                          data: data,
                          success: function(data){
                                alert('successfully added');
                                jQuery('#ajax_loader').hide();
                                alert('successfully added');
                          }
                    });
                } catch (e) {
                }
//End of our new ajax code
                this.form.action = oldUrl;
                if (e) {
                    throw e;
                }
            }
        }.bind(productAddToCartForm);
</script>

Php Code

public function addmultipleAction() {
        $productIds = $this->getRequest()->getParam('products');

        if (!is_array($productIds)) {
            $this->_goBack();
            return;
        }
        $params = $this->getRequest()->getParams();
        if ($params['isAjax'] == 1) {
            $response = array();
            foreach ($params['products'] as $p) {
                $key = 'qty' . $p;
                if (strlen(trim($params[$key]))) {
                    $response[] = $p;
                }
            }
            $productIds = $response;
            foreach ($productIds as $productId) {
                try {
                    $qty = $this->getRequest()->getParam('qty' . $productId, 0);
                    $cart = $this->_getCart();
                    $product = Mage::getModel('catalog/product')
                            ->setStoreId(Mage::app()->getStore()->getId())
                            ->load($productId)
                            ->setConfiguredAttributes($this->getRequest()->getParam('super_attribute'))
                            ->setGroupedProducts($this->getRequest()->getParam('super_group', array()));
                    $eventArgs = array(
                        'product' => $product,
                        'qty' => $qty,
                        'additional_ids' => array(),
                        'request' => $this->getRequest(),
                        'response' => $this->getResponse(),
                    );
                    $params['qty'] = $qty;
                    Mage::dispatchEvent('checkout_cart_before_add', $eventArgs);
                    $cart->addProduct($product, $params);
                    Mage::dispatchEvent('checkout_cart_after_add', $eventArgs);
                    //$cart->save();     
                    // Mage::dispatchEvent('checkout_cart_add_product', array('product'=>$product));

                    $message = $this->__('%s was successfully added to your shopping cart.', $product->getName());
                    $response['status'] = 'SUCCESS';
                    $response['message'] = $message;
                    Mage::getSingleton('checkout/session')->addSuccess($message);

                } catch (Mage_Core_Exception $e) {
                    if (Mage::getSingleton('checkout/session')->getUseNotice(true)) {
                        Mage::getSingleton('checkout/session')->addNotice($product->getName()
                                . ': ' . $e->getMessage());
                    } else {
                        Mage::getSingleton('checkout/session')->addError($product->getName() .
                                ': ' . $e->getMessage());
                    }
                } catch (Exception $e) {
                    Mage::getSingleton('checkout/session')->addException($e, $this->__('Can not add item to shopping cart'));
                }
            }
            $cart->save();
            $this->getResponse()->setBody(Mage::helper('core')->jsonEncode($response));
            return;
        }
}