index.js

// index.js
// where your node app starts

// init project
require('dotenv').config();
var express = require('express');
var app = express();
const os = require('os');

// enable CORS (https://en.wikipedia.org/wiki/Cross-origin_resource_sharing)
// so that your API is remotely testable by FCC
var cors = require('cors');
app.use(cors({ optionsSuccessStatus: 200 })); // some legacy browsers choke on 204

// http://expressjs.com/en/starter/static-files.html
app.use(express.static('public'));

// http://expressjs.com/en/starter/basic-routing.html
app.get('/', function (req, res) {
  res.sendFile(__dirname + '/views/index.html');
});

// your first API endpoint...
app.get('/api/whoami', function (req, res) {
  const ifaces=os.networkInterfaces()
  let ip;
  for (let dev in ifaces) {
    let iface = ifaces[dev]

    for (let i = 0; i < iface.length; i++) {
      let {family, address, internal} = iface[i];

      if (family === 'IPv4' && address !== '127.0.0.1' && !internal) {
        ip = address;
      }
    }
  }
  res.json(
    {
      ipaddress: ip,
      language: req.headers['accept-language'],
      software: req.headers['user-agent']
    }
  );
});

// listen for requests :)
var listener = app.listen(process.env.PORT || 3000, function () {
  console.log('Your app is listening on port ' + listener.address().port);
});