var express=require("express");var app=express();app.use(express.static('public'));app.get("/",function (req,res) {    res.sendfile("./index.html");});app.post("/data",function (req,res) {    res.send("111");});var server=app.listen(8081,function () {    var host = server.address().address;    var port = server.address().port;    console.log("server listenning on"+ port);});