Adding authentication by integrating JWT with Socket.IO

So far, all chat messages have been sent with the socket ID as the “username.” This is not a very good way to identify users in a chat room. To fix this, we are going to introduce user accounts by authenticating sockets with JWT. Follow these steps to implement JWT with Socket.IO:

1. Edit backend/src/socket.js and import jwt from the jsonwebtoken package and getUserInfoById from our service functions:

   import jwt from 'jsonwebtoken'
   import { getUserInfoById } from './services/users.js'

2. Inside the handleSocket function, define a new Socket.IO middleware by using io.use(). Middleware in Socket.IO works similarly to middleware in Express – we define a function that runs before requests are processed, as follows:

   export function handleSocket(io) {
     io.use((socket, next) => {

3. Inside this function, we check if the token was sent via the auth object (similar to how we passed...