Html动态添加css js文件

function loadjscssfile(filename,filetype){   if(filetype == "js"){      var fileref = document.createElement('script');      fileref.setAttribute("type","text/javascript");      fileref.setAttribute("src",filename);   }else if(filetype == "css"){      var fileref = document.createElement('link');      fileref.setAttribute("rel","stylesheet");      fileref.setAttribute("type","text/css");      fileref.setAttribute("href",filename);   }   if(typeof fileref != "undefined"){      document.getElementsByTagName("head")[0].appendChild(fileref);   }}loadjscssfile("do.js","js");loadjscssfile("test.css","css");