//server.js

var http = require("http");

var writefile = require("./writefile");

http.createServer(function(res, res){

    res.writeHead(200, {"Content-Type":"text/html; charset=uf-8"});

    if (res.url!=="/favicon.ico") {

        console.log('begin visit');

        res.write('hello world');

        writefile.writefile('./test.txt', 'gaoxiong'); //如果文件路径存在则添加数据，如果不存在则新建文件并且添加数据

        res.end('end');

    }

}).listen(8000);

console.log('Server running at http://127.0.0.1:8000/');

//writefile.js

var fs = require("fs");

module.exports = {

    //异步方式

    writefile:function(path, data){

        fs.writeFile(path, data, function(err){

            if (err) {

                throw(err)

            } else{

                console.log('saved success');

            }

        })

    },

    //同步方式

    writefileSync:function(path, data){

        fs.writeFileSync(path, data);

        console.log('同步写文件完成')

    }

}