如何使用jquery动态加载js，css文件实现代码

$.extend({
includePath: '',
include: function(file) {
var files = typeof file == "string" ? [file]:file;
for (var i = 0; i < files.length; i++) {
var name = files[i].replace(/^\s|\s$/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 + ">");
}
}
});

//使用方法
$.includePath = 'IP/';
$.include(['json2.js', 'jquery.tree.js', 'jquery.tree.css']);