db.js

const PORT = 3000;

const Server = require('socket.io');
const io = new Server(PORT, {
  path: '/dbyb',
  serveClient: false,
});

console.log(`Serveur lancé sur le port ${PORT}.`);

const db = Object.create(null);

io.on('connect', (socket) => {
  console.log('Nouvelle connexion');

  socket.on('get', function(field, callback){
    console.log(`get ${field}: ${db[field]}`);
    callback(db[field]);
  });

  socket.on('set', function(field, value, callback){
    if (field in db) {
      console.log(`set error : Field ${field} exists.`);
      db[field] = value;
      callback(true);
    } else {
      console.log(`set ${field} : ${value}`);
      db[field] = value;
      callback(true);
    }
  });
});