81.node.js前端html时页面格式错乱解决办法

 var http = require("http");
 var url = require("url");
 var fs = require("fs");
 var path = require("path");

 http.createServer(function(req, res) {
     //得到用户的路径
     var pathname = url.parse(req.url).pathname;
     //默认首页
     if (pathname == "/") {
         pathname = "index.html";
     }
     //拓展名
     var extname = path.extname(pathname);

     //真的读取这个文件
     fs.readFile("./" + pathname, function(err, data) {
         if (err) {
             //如果此文件不存在，就应该用404返回
             fs.readFile("./static/404.html", function(err, data) {
                 res.writeHead(404, {
                     "Content-type": "text/html;charset=UTF8"
                 });
                 res.end(data);
             });
             return;
         };
         //MIME类型，就是
         //网页文件：  text/html
         //jpg文件 :   image/jpg
         var mime = getMime(extname);
         res.writeHead(200, {
             "Content-type": mime
         });
         res.end(data);
     });

 }).listen(3000, "127.0.0.1");

 function getMime(extname) {
     switch (extname) {
         case ".html":
             return "text/html";
             break;
         case ".jpg":
             return "image/jpg";
             break;
         case ".css":
             return "text/css";
             break;
     }
 }