学习如何用JS实现动态加载Js文件和Css文件

$.extend({ 
   includePath: '', 
   include: function(file) { 
    var files = typeof file == "string" ? [file]:file; 
    for (var i = 0; i < files.length; i++) { 
      var name = files[i].replace(/^\s|\s$/g, ""); 
      var att = name.split('.'); 
      var ext = att[att.length - 1].toLowerCase(); 
      var isCSS = ext == "css"; 
      var tag = isCSS ? "link" : "script"; 
      var attr = isCSS ? " type='text/css' rel='stylesheet' " : " language='javascript' type='text/javascript' "; 
      var link = (isCSS ? "href" : "src") + "='" + $.includePath + name + "'"; 
      if ($(tag + "[" + link + "]").length == 0) document.write("<" + tag + attr + link + "></" + tag + ">"); 
    } 
  } 
}); 

$.include('http://www.jb51.net/include/dedeajax.js'); 
$.include('http://www.jb51.net/templets/skins/style/android.css'); 

$.includePath='www.jb51.net/html/'; 
$.include([dedeajax.js','android.css']);