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');