How to isolate events in socket.io?

Question

Node.js

For example, there is a code

io.on('connection', function(socket){
    socket.on('join', (room) => {
      console.log(room, socket.id)
    })
  });

If you connect two users, then accept one on the server, it works for two users

{ room: '12ds23sfdg234' } '/#RIbdtzB2xseyeKb8AAAA'
{ room: '12ds23sfdg234' } '/#THTZ8erZYt4RyF3kAAAB'

How can this be fixed?
Thanks

Answer 1

Well, it's all right.
The code fulfills for each connection.
Common code for all.
What to isolate?