一，编写服务端JS
//加载http模块，创建服务器
var http=require('http');
http.createServer(function(req,res){
//回调
res.writeHead(200,{'Content-Type':'text/plain'});
res.end("hello World\n");
}).listen(1337,'127.0.0.1');
console.log("Server running at http://127.0.0.1:1337");
