Node.js - how to use one connection with socket.io for several rooms

I need to do a chat, therefore I guess to using node + socket.io. Except that, one person may be on several room in same time. Although we can use io.of('/room1')... This forces, browser side, to make several connections to several rooms.

Have you got a best suggestion or idea ?

Thank you in advance.

You can think of having a "default" room, which will be helpful to maintain presence i.e status of the user whether he is online or offline. This will contain a big list of all users who are online in your application

For each chat that happens between users, better to have dynamic rooms created for each conversation.