How to use socket.io instance in Node.js controllers?

Question

JavaScript

If I want to use a socket.io instance in a controller, is global.io = io really awful? If so, how can I reach io from another of my controllers?
index.js

const server = app.listen(3000, '127.0.0.1', () => {
    console.log("Node.js listening on port 3000");
});

// socket
const io = require('socket.io')(server);
const sharedsession = require("express-socket.io-session");

global.io = io;
io.use(sharedsession(session));
require('./socket/socket')(io);

socket.js

module.exports = (io) => {
    io.on('connection', socket => {
        console.log('a user connected');

        socket.on("event", () => {
            
        });
    });
};

Answer 1

Just pass io to controller instances, or yes, global variables.
PS (io) => {is spelled as io => {.