          return
        }

        var head = document.head || document.getElementByTagName("head")[0] || document.documentElement;
        var script = document.createElement("script");
        script.setAttribute("type", "text/javascript");
        script.setAttribute("src", script_file_url);
        script.setAttribute("charset", "utf-8");

        if (script_id) {
            script.setAttribute("id", script_id);
            var scriptId = document.getElementById(script_id);
            // 如果已经