How to create rooms in Node Socket.io?

To create rooms in Node Socket.io, we call in and join.

For instance, on client side, we write

const socket = io.connect();
socket.emit("create", "room1");

to call emit to emit the create event with the room name.

On server side, we write

io.sockets.on("connection", (socket) => {
  socket.on("create", (room) => {
    socket.join(room);
  });
});

to call on to listen for the create event and call join to create the room.

Then we can send messages to the room with

io.sockets.in(room).emit("event", data);

by call in with the room name.