Javascript倒计时仅在页面重新加载时

Question

我有opencart模块每日交易，但倒数计时器无效。

功能代码：

<?php
class ModelCatalogSpecialPriceCountDown extends Model {

public function getProductSpecialDates($product_id) {

    (string) $display_output = null;
    (string) $minute = 60;
    (string) $hour = 60 * $minute;
    (string) $day = 24 * $hour;

    if ($this->customer->isLogged()) {
        $customer_group_id = $this->customer->getCustomerGroupId();
    } else {
        $customer_group_id = $this->config->get('config_customer_group_id');
    }   

    $query = $this->db->query("SELECT date_start, date_end  FROM " . DB_PREFIX . "product_special WHERE product_id = '" . (int)$product_id . "' AND customer_group_id = '" . (int)$customer_group_id . "' AND ((date_start = '0000-00-00' OR date_start < NOW()) AND (date_end = '0000-00-00' OR date_end > NOW())) ORDER BY priority ASC, price ASC LIMIT 1");

    if ($query->num_rows) {

        $time_left = strtotime($query->row["date_end"]) - strtotime(date('Y-m-d'));
        $days_left = floor($time_left/$day);

        if ($time_left > 0)
        {
            $display_output = getdate();
            $display_output["days_left"] = $days_left;
        }
    }

    return $display_output;

}
}
?>

以及使用它的代码：

<!-- Countdown  start -->
        <div id="defaultCountdown<?php echo $product['product_id'];?>" class="countdown_dashboard"></div>
        <script type="text/javascript"><!--
        $(document).ready(function() {
                $('#defaultCountdown<?php echo $product["product_id"]; ?>').countdown({ 
                    until: new Date(<?php echo $product['yleft'];?>, <?php echo $product['mleft'];?> - 1, <?php echo $product['dleft'];?>)
                    }); 
            });

        //-->
        </script>

我的倒计时不起作用，只有当我刷新页面时，数字才会改变。