server.js

const express = require('express')
const app = express()
const http = require('http')
const {Server} = require('socket.io')
const ACTIONS = require('./src/Actions')

const server = http.createServer(app)
const io = new Server(server)

const userSocketMap = {}
function getAllConnnectedClients(roomId) {
    return Array.from(io.sockets.adapter.rooms.get(roomId) || []).map(
        (socketId) => {
            return {
                socketId,
                username: userSocketMap[socketId]
            }
        }
    )
}

io.on('connection', (socket) => {
    console.log('socket connected', socket.id)

    socket.on(ACTIONS.JOIN, ({roomId, username}) => {
        userSocketMap[socket.id] = username
        socket.join(roomId)
        const clients = getAllConnnectedClients(roomId)
        // console.log(clients)
        clients.forEach(({socketId}) => {
            io.to(socketId).emit(ACTIONS.JOINED, {
                clients,
                username,
                socketId: socket.id,
            })
        })
    })

    socket.on(ACTIONS.CODE_CHANGE, ({roomId, code}) => {
        socket.in(roomId).emit(ACTIONS.CODE_CHANGE, { code })
    })

    socket.on('disconnecting', () => {
        const rooms = [...socket.rooms]
        rooms.forEach((roomId) => {
            socket.in(roomId).emit(ACTIONS.DISCONNECTED,{
                socketId: socket.id,
                username: userSocketMap[socket.id],
            })
        })
        delete userSocketMap[socket.id]
        socket.leave()
    })
})

const PORT = process.env.PORT || 5000
server.listen(PORT, () => console.log(`Listening on port ${PORT}`))