nodejs如何实现的简单web服务器功能

<script src="jquery-1.12.1.js"></script>
<script type="text/javascript">
 $.ajax({
 url:'http://192.168.0.114:3000',//服务器地址
 type:'post',
 timeout:30,
 dataType:'json',
 data:{
 "username":username,
 "password":password
 },
 success:function(res){
 console.log(JSON.stringify(res));
 },
 err:function(err){
 alert(err);
 }
});

var http = require('http');
var url = require('url');
var qs = require('querystring');
http.createServer(function(req,res){
 res.writeHead(200,{'Content-Type':'text/plain;charset=UTF-8','Access-Control-Allow-origin':'*'});
 if(req.method.toUpperCase() == 'GET'){
 var query = url.parse(req.url, true).query;// 接受的数据
 res.end(JSON.stringify(query));
 }else if(req.method.toUpperCase() == 'POST'){
 var postData = '';
 req.on('data',function(data){
 postData += data; //接受的数据
 });
 req.on('end',function(){
 var query = qs.parse(postData);
 res.end(JSON.stringify(query));//返回的数据
 });
 }
}).listen('3000',function(){
 console.log('this is callback');
});
console.log('server is running');