Unable to establish connection between Node.JS and React-Native (Socket.IO)

Question

I'm new to React and Node and i'm trying to make a simple WebSocket using Socket.IO which gonna simply send greetings to all connected users and the user will respond to the server.

The Node.JS server is running on a Windows PC while the React-Native app is running on both iOS and Android devices.

Node.JS server code is the following

var app = require('express')();
var http = require('http').createServer(app);
var io   = require('socket.io')(http);
const bodyParser = require('body-parser');
const mysql = require('mysql');


const connection = mysql.createPool({
  host     : 'localhost',
  user     : 'root',
  password : 'block',
  database : 'visualpos'
});

// Creating a GET route that returns data from the 'users' table.
app.get('/prenotazioni', function (req, res) {
    // Connecting to the database.
    connection.getConnection(function (err, connection) {

    // Executing the MySQL query (select all data from the 'users' table).
    connection.query("SELECT Data, Importo_Doc FROM tabella_pagamenti", function (error, results, fields) {
      // If some error occurs, we throw an error.
      if (error) throw error;

      // Getting the 'response' from the database and sending it to our route. This is were the data is.
      res.send(results)
    });
    connection.release();
  });
});

app.get('/', function(req, res){
  res.send('<h1>Hello World</h1>');
});

// Starting our server.
http.listen(3000, () => {
 console.log('In ascolto sulla porta *:3000');
});

io.emit('saluta', 'Ciao dal server :)');
io.on('connected', (data) => {
   console.log(data);
});

Actually GET part of the code works perfectly but the Socket.IO seems death . The client doesn't get any response and server the same i think the Socket.IO server simply doesn't start..

In XCode Debug i get the following errors when the app is running on the iPhone

And i even get on both devices warning "Unrecognized WebSocket connection option(s) 'agent', 'perMessageDeflate',..."

And here is the code i'm using in React-Native

import io from 'socket.io-client'

    var socket = io('http://192.168.100.50:3000', {
        jsonp: false,
        transports: ['websocket'],
        autoConnect: true,
        reconnection: true,
        reconnectionDelay: 500,
        reconnectionAttempts: Infinity
    });

    componentDidMount(){
     socket.emit('connected','we');
     socket.on('saluta',(data) => { alert(data); });
    }

Answer 1

On socket.io getStarted section, they use a "connection" event instead of "connected" ( https://socket.io/get-started/chat/ ).

 io.on('connection', function(socket){ console.log('a user connected'); socket.on('disconnect', function(){ console.log('user disconnected'); }); });