Backend75-120 min
WebSocket Realtime Chat
Use WebSockets for bidirectional events, join users to scoped rooms, persist messages, and recover state after reconnects.
Socket.IONode.jsReactPostgreSQL
Prerequisites
- A Node.js server and React frontend.
- Authenticated users.
- A database table for messages or events.
1
Plan the implementation
Start by choosing the exact page, route, API, or deployment surface you want to improve. A narrow target makes the implementation measurable and easier to verify.
- Write down the current behavior and the user-facing problem it creates.
- Pick one measurable success signal such as bundle size, latency, error rate, security coverage, or UI responsiveness.
- Identify the files, routes, providers, and environment variables involved.
- Create a rollback note before changing production-sensitive configuration.
2
Set up the required tools
Install or configure only the tools needed for this implementation. Keep config close to the feature so future developers can find the moving parts quickly.
Implementation snippet
npm install socket.io socket.io-clientChecklist
- Dependencies are added to the correct workspace package.
- Environment variables are documented in `.env.example` when needed.
- Local development still starts without production-only secrets.
- The change is small enough to review in one pull request.
3
Implement the core pattern
- Authenticate the socket connection before accepting events.
- Use rooms for conversations, projects, teams, or documents.
- Persist messages before broadcasting them.
- Send events only to users allowed to access the room.
- Refetch missed messages after reconnect.
Implementation snippet
io.use(async (socket, next) => {
const user = await verifySocketToken(socket.handshake.auth.token);
socket.data.user = user;
next();
});
io.on("connection", (socket) => {
socket.on("room:join", (roomId) => socket.join(`room:${roomId}`));
});4
Handle edge cases
Checklist
- Unauthorized users cannot join private rooms.
- Messages persist even if a client disconnects.
- Reconnect logic avoids duplicate visible messages.
- Server logs include connection and error events.
5
Verify before production
- Run the app locally and test the normal success path.
- Test one failure path, one empty state, and one slow-network or retry path.
- Run the project build and any related unit or integration tests.
- Check browser console, server logs, and network responses for hidden warnings.
- Document the final behavior, commands used, and any follow-up work.