socket.io get rooms which socket is currently in

Question

Is it possible to get rooms which socket is currently in, without calling

io.sockets.clients(roomName)

for every room name and looking for

Answer 1

You can save room in socket itself when it joins a room

// join room
socket.join(room);

// update socket's rooms
if (socket.rooms) {
    socket.rooms.push(room);
} else {
    socket.rooms = [room];
}

Later you can retrieve all rooms that the socket is in by simply

socket.rooms

From the Server API documentation:

socket.rooms (object)
A hash of strings identifying the rooms this client is in, indexed by room name.

https://socket.io/docs/server-api/#socket-rooms