# Spot the bug: Node.js / NestJS

> One snippet. Find the bug, or prove there isn't one.

Daily challenge: 2026-08-19 (UTC) · Mid-Level

```typescript
import { WebSocketGateway, SubscribeMessage, MessageBody, ConnectedSocket } from '@nestjs/websockets';
import { Socket } from 'socket.io';
import { MessagesService } from './messages.service';

@WebSocketGateway({ namespace: 'chat' })
export class ChatGateway {
  constructor(private readonly messages: MessagesService) {}

  @SubscribeMessage('joinRoom')
  async joinRoom(
    @ConnectedSocket() client: Socket,
    @MessageBody() data: { roomId: string },
  ) {
    client.join(data.roomId);
    const history = await this.messages.getRoomHistory(data.roomId);
    client.emit('history', history);
  }
}
```

## Your verdict

- Security flaw
- Logic bug
- Code style
- No issue

One attempt per day. The answer shows up right after.

---

Source: SharpSkill (https://sharpskill.dev), tech interview preparation for your real stack.
HTML version of this page: https://sharpskill.dev/en/daily/node-nestjs