Rooms
- Node.js course
- Advanced
- Lesson 46/83
- 5 min
Learn room management with Socket.io rooms.
Rooms
A room is a channel that groups clients. With socket.join("roomName") you add a client to a room. Then io.to("roomName").emit(...) sends a message only to clients in that room.
Example: socket.join("room-42"); io.to("room-42").emit("message", "Hello room");. This sends Hello room to clients who joined room-42. Rooms are ideal for group chat, channel-based notifications and multiplayer games. With socket.leave("roomName") you remove a client from a room. Room names are strings; you can name them anything.
io.to('room').emit
To send a message to a room you use io.to("room").emit(event, data). This delivers the message only to clients in that room. io.emit goes to all clients; io.to goes to a single room.
Example: io.to("room-42").emit("message", { text: "Hello" });. All clients in room-42 receive the message event. To send to multiple rooms you write io.to("room-1").to("room-2").emit(...). Rooms are kept on the server side; they are invisible to the client. With socket.broadcast.to("room").emit(...) you send to other clients in the room (not yourself).
Practice Room join and broadcast
Use the io object below. Define io.on("connection", (socket) => { socket.join("room-42"); io.to("room-42").emit("message", "Hello"); }). Print "rooms ready" with console.log.
Starter code
const socketIo = require("socket.io");
const io = socketIo();
// Inside io.on, write socket.join and io.to calls
// write here
// Print "rooms ready"
// write hereSample solution
const socketIo = require("socket.io");
const io = socketIo();
io.on("connection", (socket) => {
socket.join("room-42");
io.to("room-42").emit("message", "Hello");
});
console.log("rooms ready");Expected output
rooms ready
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does socket.join('room-1') do?
socket.join("room-1")- Deletes the client
- Adds the client to the room Correct answer
- Sends a message to all clients
- Closes the server
Explanation: socket.join adds the client to the room.
2 Complete the socket.join line
socket.join("____");socket.join("oda-42");Explanation: socket.join('oda-42') adds the client to the room.
3 Match each piece to its role
| Term | Meaning |
|---|---|
socket.join |
Adds client to room |
socket.leave |
Removes client from room |
io.to |
Sends to that room |
room name |
Channel identifier |