mad.js

function showLobby(session) {
  var lobby = new LobbyClient({session: session});
  var lobbyUi = new LobbyUi({element: rootElement});

  var processLobbyEventsUntilNotJoinRoom = lobbyUi.poll().bind(function(event) {
    if (event.type === LobbyUi.EVENTS.JOIN_ROOM) {
      this.cont(null, event.id);
    } else {
      return processLobbyEventsUntilNotJoinRoom;
    }
  });

  return lobby.getAllRooms().bind(lobbyUi.rooms
  ).skip(lobbyUi.start()).skip(processLobbyEventsUntilNotJoinRoom);
}