动态载入CSS文件

转载：http://dev.mjxy.cn/a-355.aspx

// Dynamic CSS file loading

var CSS = {

        load: /*static*/ function (url_, /*optional*/ media_) {

                // We are preventing loading a file already loaded
                var _links = document.getElementsByTagName("link");
                if (_links.length > 0 && _links["href"] == url_) return;

                // Optional parameters check
                var _media = media_ === undefined || media_ === null ? "all" : media_;

                var _elstyle = document.createElement("link");
                _elstyle.setAttribute("rel", "stylesheet");
                _elstyle.setAttribute("type", "text/css");
                _elstyle.setAttribute("media", _media);
                _elstyle.setAttribute("href", url_);

                var _head = document.getElementsByTagName("head")[0];
                _head.element.appendChild(_elstyle);

        }

};