Ajax Update Cart Items(Mini Cart) via function.php for WPEC

gistfile1.php

/**
* add a custom AJAX request handler
*/
function theme_wpsc_cart_update() {
    $data = array(
        'cart_count' => wpsc_cart_item_count(),
        'cart_total' => wpsc_cart_total_widget(),
    );
    echo json_encode($data);
    exit;
}
add_action('wp_ajax_theme_wpsc_cart_update', 'theme_wpsc_cart_update');
add_action('wp_ajax_nopriv_theme_wpsc_cart_update', 'theme_wpsc_cart_update');
 
/**
* add JavaScript event handler to the page footer
*/
function theme_wpsc_footer() {
    if (!is_admin()) {
    ?>
 
    <script>
    jQuery(function($) {
        /**
        * catch WP e-Commerce cart update event
        * @param {jQuery.Event} event
        */
        $(document).on("wpsc_fancy_notification", function(event) {
            updateMinicart();
        });
 
        /**
        * catch AJAX complete events, to catch clear cart
        * @param {jQuery.Event} event
        * @param {jqXHR} xhr XmlHttpRequest object
        * @param {Object} ajaxOpts options for the AJAX request
        */
        $(document).ajaxComplete(function(event, xhr, ajaxOpts) {
            // check for WP e-Commerce "empty_cart" action
            if ("data" in ajaxOpts && ajaxOpts.data.indexOf("action=empty_cart") != -1) {
                updateMinicart();
            }
        });
 
        /**
        * submit AJAX request to update mini-cart
        */
        function updateMinicart() {
            // ask server for updated data
            $.ajax({
                url: "<?php echo admin_url('admin-ajax.php'); ?>",
                cache: false,
                dataType: "json",
                data: { action: "theme_wpsc_cart_update" },
                success: function(data) {
                    // update our mini-cart elements
                    $("#theme-checkout-count").html(data.cart_count);
                    $("#theme-checkout-total").html(data.cart_total);
                }
            });
        }
 
    });
    </script>
 
    <?php
    }
}
add_action('wp_footer', 'theme_wpsc_footer');