Access SocketIO from another file

Question

I'm trying to emit to all the sockets connected from a seperate file. However I cannot seem to figure it out.

Socket.js

var socketio = require('socket.io');
var users = require('./modules/users');

var io = socketio();
socket.io = io;

io.on('connection', function(socket){
  //Stuff
  console.log('Hello :)');
});

module.exports = socket;

Users.js

var socket = require('../socket');

function news(){
    socket.io.sockets.emit('news', {
        message: 'Woah! Thats new :)'
    })
}

setInterval(function(){
    news();
}, 5 * 1000);

However, socket in users.js seems to be empty and I can't seem to access to io object. How can I make it so I can emit to all users? Without parsing the io.sockets to the news function or moving my function to the socket file?

Answer 1

You can define io object with let as global variable in utils and io functions there. You can call these functions from any file. For example:

// app.js

const { socketConnection } = require('./utils/socket-io');
const http = require('http');
const express = require('express');

const app = express();
const server = http.createServer(app);
socketConnection(server);

// utils/socket-io

let io;
exports.socketConnection = (server) => {
  io = require('socket.io')(server);
  io.on('connection', (socket) => {
    console.info(`Client connected [id=${socket.id}]`);
    socket.join(socket.request._query.id);
    socket.on('disconnect', () => {
      console.info(`Client disconnected [id=${socket.id}]`);
    });
  });
};

exports.sendMessage = (roomId, key, message) => io.to(roomId).emit(key, message);

exports.getRooms = () => io.sockets.adapter.rooms;

// any file

const { sendMessage } = require('../utils/socket-io');

const foo = async () => {
  const roomId = '12345';
  const key = 'new-order';
  const message = 'new order assigned';
  
  sendMessage(roomId, key, message);
};