Broadcasting messages in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the WebSocketGateway decorator.

NestJS

import { [1] } from '@nestjs/websockets';

@WebSocketGateway()
export class EventsGateway {}

Drag options to blanks, or click blank then click option'

AOnGatewayInit

BWebSocketServer

CSubscribeMessage

DWebSocketGateway

Attempts:

3 left

💡 Hint

Common Mistakes

Importing WebSocketServer instead of WebSocketGateway.

Using SubscribeMessage decorator in place of WebSocketGateway.

The WebSocketGateway decorator is imported from '@nestjs/websockets' to define a WebSocket gateway.

2fill in blank

medium

Complete the code to broadcast a message to all connected clients.

NestJS

import { WebSocketGateway, WebSocketServer } from '@nestjs/websockets';
import { Server } from 'socket.io';

@WebSocketGateway()
export class EventsGateway {
  @WebSocketServer()
  server: Server;

  broadcastMessage(message: string) {
    this.server.[1]('message', message);
  }
}

Drag options to blanks, or click blank then click option'

Aemit

Bsend

Cbroadcast

Don

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'send' which is not a method on the server instance.

Using 'broadcast' which is used differently in Socket.IO.

The 'emit' method sends an event to all connected clients in Socket.IO.

3fill in blank

hard

Fix the error in the method that broadcasts a message only to other clients except the sender.

NestJS

import { WebSocketGateway, WebSocketServer, SubscribeMessage, MessageBody, ConnectedSocket } from '@nestjs/websockets';
import { Server, Socket } from 'socket.io';

@WebSocketGateway()
export class EventsGateway {
  @WebSocketServer()
  server: Server;

  @SubscribeMessage('sendMessage')
  handleMessage(@MessageBody() message: string, @ConnectedSocket() client: Socket) {
    [1].broadcast.emit('message', message);
  }
}

Drag options to blanks, or click blank then click option'

Asocket

Bclient

Cconnection

Dserver

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'server.broadcast.emit' which sends to all including sender.

Using an undefined variable like 'socket' or 'connection'.

The 'client' parameter is the socket instance; broadcasting to others uses 'client.broadcast.emit'.

4fill in blank

hard

Fill both blanks to create a method that sends a private message to a specific client by id.

NestJS

import { WebSocketGateway, WebSocketServer } from '@nestjs/websockets';
import { Server } from 'socket.io';

@WebSocketGateway()
export class EventsGateway {
  @WebSocketServer()
  server: Server;

  sendPrivateMessage(clientId: string, message: string) {
    this.server.sockets.sockets.get([1]).[2]('privateMessage', message);
  }
}

Drag options to blanks, or click blank then click option'

AclientId

Bsend

Cemit

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'send' instead of 'emit' which is the correct Socket.IO method.

Using 'id' instead of 'clientId' to get the socket.

Use 'clientId' to get the socket, then 'emit' to send the event to that client.

5fill in blank

hard

Fill all three blanks to create a method that broadcasts to a room except the sender.

NestJS

import { WebSocketGateway, WebSocketServer, ConnectedSocket } from '@nestjs/websockets';
import { Server, Socket } from 'socket.io';

@WebSocketGateway()
export class EventsGateway {
  @WebSocketServer()
  server: Server;

  broadcastToRoom(room: string, message: string, client: Socket) {
    client.[1].to([2]).[3]('roomMessage', message);
  }
}

Drag options to blanks, or click blank then click option'

Abroadcast

Broom

Cemit

Dserver

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'server' instead of 'broadcast' to exclude sender.

Using 'send' instead of 'emit' to send the event.

Use 'client.broadcast.to(room).emit' to send a message to all clients in the room except the sender.