Node http File system and JSON exp

index.js

const http = require('http')
const url = require("url");
const fs = require('fs');

const port = 3000

const requestHandler = (request, response) => {
  var pathname = url.parse(request.url).pathname;
  console.log("Request for " + pathname + " received. "+(pathname === '/persons'));
  var json = JSON.parse(fs.readFileSync('./persons.json', 'utf8'));

  if (pathname === '/persons') {

    if (request.method == 'POST') {
      console.log("POST");
      var body = '';
      request.on('data', function (data) {
          body += data;
      });
      request.on('end', function () {
          console.log(body);
          json.data.push(body)
          json = JSON.stringify(json); //convert it back to json
          fs.writeFile('./persons.json', json, 'utf8', function(){
            response.writeHead(200, {'Content-Type': 'application/json'});
            response.end(JSON.stringify(body));
          }); // write it back
      });
    }
    else
    {
      response.writeHead(200, {'Content-Type': 'application/json'});
      response.end(JSON.stringify(json));
    }
  }

 response.end('invalid URL , try /persons');

}


const server = http.createServer(requestHandler)

server.listen(port, (err) => {
  if (err) {
    return console.log('something bad happened', err)
  }

  console.log(`server is listening on ${port}`)
})

package.json

{
  "name": "node_http_json",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
     "start": "node index.js"
  },
  "author": "",
  "license": "ISC"
}

persons.json

{"data":[]}