Building a real-time badge scanning flow for a Visitor Management System: Need help with async state handling!

Ali T — Mon, 07 Sep 2026 13:25:25 +0000

Hey DEV Community! 👋

I'm currently working on building a real-time badge scanning and check-in flow for an enterprise visitor management system project, but as a relatively new developer, I've run into an async state management challenge that I can't quite wrap my head around.

The Use Case

When a visitor scans their badge at the kiosk:

An edge device sends an asynchronous event via WebSockets (ws://) to our backend service.
The backend validates the badge UUID, fetches guest privileges, and updates the database state.
The UI needs to immediately reflect the state change (pending -> verified -> granted / denied) without lag or race conditions.

The Problem / Rookie Question

I'm using React on the frontend and Node.js/Express on the backend with Socket.IO. When multiple visitors scan badges rapidly in succession:

Sometimes the state updates out of order in the frontend state container.
If a socket drops and reconnects, state sync gets stale or duplicates events.

What is the recommended pattern for handling fast async WebSocket event streams and ensuring UI state consistency in React for this type of system? Should I be using optimistic UI updates with an event sequence log, or buffering incoming scans in Redux/Zustand middleware?

Any advice, code snippets, or best practices from experienced devs would be super appreciated! Thanks in advance!

DEV Community: Ali T

Building a real-time badge scanning flow for a Visitor Management System: Need help with async state handling!

The Use Case

The Problem / Rookie Question