socketing.js

var rooms = {};
io.sockets.on("connection", function(socket){
  socket.on("create room", function(roomName){
    if(!rooms[roomName]){
      rooms[roomName] = [];
    }
      rooms[roomName].push(socket);
  });
  socket.on("message", function(data){
    rooms[data.roomName].forEach(function(s){
      io.sockets.socket(s.id).emit(data.message);
    })
  })
})