get the socket name list in node.js

I am currently creating the chatting app.

I want to get the all the chat room list.

or else all the connedted socket's name list

        //now in the room
        socket.join(roomID);   <---  want to get all connedted socket list
        socket.nickname = name;            
        socket.roomIn = roomID;
        socket.roomName = room;