Simple Socket.IO server and client on JavaScript

client.js

const PRIVATE_CHANNEL = 'channel_private';
const GLOBAL_CHANNEL = 'default';

var io = require('socket.io-client');
var socket = io.connect('http://localhost:8080');
var channel = null;

socket.on('connect', function () {
  console.log('CONNECT');

  socket.on('events.new', function (data) {
    console.log('EVENT', data)
  });

  socket.on('views.new', function (data) {
    console.log('NEW VIEW OF EVENT', data)
  });

  socket.on('messages.new', function (data) {
    console.log('NEW PRIVATE MESSAGE', data)
  });

  socket.on('disconnect', function () {
    console.log('disconnect')
  });

  // Kick it off
  // Can be any channel. For private channels, Laravel should pass it upon page load (or given by another user).
  socket.emit('subscribe-to-channel', {channel: PRIVATE_CHANNEL});
  console.log('SUBSCRIBED TO <' + PRIVATE_CHANNEL + '>');

  socket.emit('subscribe-to-channel', {channel: GLOBAL_CHANNEL});
  console.log('SUBSCRIBED TO <' + GLOBAL_CHANNEL + '>');
});

server.js

const SERVER_PORT = 8080;

const app = require('express')();
const server = require('http').Server(app);
const io = require('socket.io')(server);
const redis = require('redis');
const ioredis = require('socket.io-redis');

io.adapter(ioredis({
  host: process.env.REDIS_HOST,
  port: process.env.REDIS_PORT
}));

function isJson(str) {
  try {
    JSON.parse(str);
  } catch (e) {
    return false;
  }
  return true;
}

/*
 * Redis pub/sub
 */

// Listen to local Redis broadcasts
const sub = redis.createClient({
  host: process.env.REDIS_HOST,
  port: process.env.REDIS_PORT
});

sub.on('error', function (error) {
  console.log('ERROR ' + error)
});

sub.on('subscribe', function (channel, count) {
  console.log('SUBSCRIBE', channel, count)
});

// Handle messages from channels we're subscribed to
sub.on('message', function (channel, payload) {
  console.log('INCOMING MESSAGE', channel, payload);

  if (isJson(payload)) {
    payload = JSON.parse(payload);
  }

  // Merge channel into payload
  payload.data._channel = channel;

  // Send the data through to any client in the channel room (!)
  // (i.e. server room, usually being just the one user)
  io.sockets.in(channel).emit(payload.event, payload.data)
});

/*
 * Server
 */

// Start listening for incoming client connections
io.sockets.on('connection', function (socket) {

  console.log('NEW CLIENT CONNECTED');

  socket.on('subscribe-to-channel', function (data) {
    if (isJson(data)) {
      data = JSON.parse(data);
    }

    console.log('SUBSCRIBE TO CHANNEL', data);

    // Subscribe to the Redis channel using our global subscriber
    sub.subscribe(data.channel);

    // Join the (somewhat local) server room for this channel. This
    // way we can later pass our channel events right through to
    // the room instead of broadcasting them to every client.
    socket.join(data.channel)
  });

  socket.on('unsubscribe-from-channel', function (data) {
    if (isJson(data)) {
      data = JSON.parse(data);
    }

    console.log('UNSUBSCRIBE FROM CHANNEL', data);

    // Unsubscribe from the Redis channel
    sub.unsubscribe(data.channel);

    // Leave from this channel
    socket.leave(data.channel)
  });

  socket.on('disconnect', function () {
    console.log('DISCONNECT')
  });

});

server.listen(SERVER_PORT, function () {
  console.log('Listening on port ' + SERVER_PORT);
});