From a quick scan of the feature, it appears to be server based.
Follow e.g. psitsmike.com - psitsmike Resources and Information. and node.js - Dynamic rooms in Socket.io - Stack Overflow to implement it on the server. On the client you’d only need an emit call to switch to the new room and the server handles the switch, in the stack overflow answer the server then emits a message back to the client to do any room update logic (in that example ‘updaterooms’).