How can I export socket.io connection to another controller - node.js

Question

I am stuck in a problem.
I am making a Socket.IO connection in the bin file which is working, but can anyone tell me how I can export this connection to different controller. This is my bin file code.
var app = require('../app');
var debug = require('debug')('userservice:server');
var http = require('http');
/**
* Get port from environment and store in Express.
*/
var port = normalizePort(process.env.PORT || '3015');
app.set('port', port);
/**
* Create HTTP server.
*/
var server = http.createServer(app);
var io = require('socket.io')(server);
io.on('connection', (socket) => {
console.log('Connection made #######################################################.', socket.id);
socket.on('disconnect', () => {
console.log('Connection disconnected #######################################################.', socket.id);
});
});
/**
* Listen on provided port, on all network interfaces.
*/
server.listen(port);
server.on('error', onError);
server.on('listening', onListening);

Answer 1

There is plenty of techniques can be used to re-use the socket instance, an easy and simple one is to create a singular class, to be able to:
Initiate socket instance
Export the instance to other modules
socket.js:
let io;
module.exports = {
init: (server) => {
io = require('socket.io').listen(server); io.origins('*:*');
return io;
},
get: () => {
if (!io) {
throw new Error("socket is not initialized");
}
return io;
}
};
server.js:
const app = require('../app');
const http = require('http');
/**
* Get port from environment and store in Express.
*/
const port = '3015';
app.set('port', port);
/**
* Create HTTP server.
*/
const server = http.createServer(app);
const io = require('./socket.js').init(server);
io.on('connection', (socket) => {
console.log('Connection success', socket.id);
socket.on('disconnect', () => {
console.log('Connection disconnected', socket.id);
});
}
Now you can use it in other modules.
const io = require('./socket.js').get();

Answer 2

You could just create a socket.io controller module that exports a function that you call for every new connection.
So, in your current server file, you add this:
const {socketConnected} = require('socketController.');
And, you modify this portion to call it for each new socket:
var server = http.createServer(app);
var io = require('socket.io')(server);
io.on('connection', (socket) => {
console.log('Connection made #######################################################.', socket.id);
// tell controller about new socket (and pass the io instance)
socketConnected(socket, io);
socket.on('disconnect', () => {
console.log('Connection disconnected #######################################################.', socket.id);
});
});
Then, your socket controller can be like this:
module.exports.socketConnected = function(socket, io) {
// new socket.io socket connected
console.log(`controller: got socket.io connection ${socket.id}`);
// register appropriate event handlers on the socket here
}

Answer 3

We can export the socket module in every file by creating a global object in such a way.
let io;
const connectedUsers = [];
const setupSocketIO = function (server) {
io = require('socket.io')(server, { cors: { origin: '*' } });
io.on('connection', function (socket) {
connectedUsers[connectedUsers.length] = socket.id;
socket.on('getConnectedUsers', () => {
io.sockets.emit('returnConnectedUsers', connectedUsers.length);
});
socket.on('disconnect', () => {
let socketIdToRemoveIndex = -1;
for (let i = 0; i < connectedUsers.length; i++) {
if (connectedUsers[i] === socket.id) {
socketIdToRemoveIndex = i;
}
}
if (socketIdToRemoveIndex !== -1) {
connectedUsers.splice(socketIdToRemoveIndex, 1);
}
io.sockets.emit('connectedUsers', connectedUsers.length);
});
});
};
const Socket = function () {
return {
emit: function (event, data) {
io.sockets.emit(event, data);
},
to: function (roomId, event, data) {
io.sockets.to(roomId).emit(event, data);
},
};
};
exports.setupSocketIO = setupSocketIO;
exports.Socket = Socket;
And in file or componenet, we want to use.
const getAllProjects = async (req, res) => {
let Socket = require('../sockets').Socket();
Socket.emit('SOCKET_PUSH_NOTIFICATION', { data: 'This is random data' });
Socket.to('SOCKET_PUSH_NOTIFICATION', 'event', { data: 'Muhammad' });
}