Building Offline-First React Applications

---
name: Building Offline-First React Applications
description: Techniques for developing React applications that function seamlessly without an internet connection.
category: React Cursor Rules
---

## Objective

Ensure React applications are designed to operate effectively offline, providing a seamless user experience regardless of network availability.

## Guidelines

1. **Implement Service Workers for Asset Caching**
   - Register a service worker to cache essential assets (HTML, CSS, JavaScript) and API responses, enabling the application to load and function offline.

2. **Utilize IndexedDB for Local Data Storage**
   - Use IndexedDB to store significant amounts of structured data locally, allowing the application to access and modify data without a network connection.

3. **Manage Offline Actions with a Queue System**
   - Queue user actions performed offline and synchronize them with the server once connectivity is restored, ensuring data consistency and integrity.

4. **Detect Network Status Changes**
   - Implement listeners to monitor network status and trigger appropriate actions, such as syncing queued data when the application goes online.

5. **Provide User Feedback on Connectivity Status**
   - Display indicators to inform users of their current connectivity status and the state of data synchronization processes.

6. **Handle Data Synchronization Conflicts**
   - Develop strategies to resolve conflicts that may arise during data synchronization, such as implementing version control or timestamp checks.

7. **Optimize Performance with Code Splitting and Lazy Loading**
   - Use code splitting and lazy loading to reduce initial load times and improve performance, especially in offline scenarios.

8. **Test Offline Functionality Thoroughly**
   - Simulate offline conditions during development and testing to ensure the application behaves correctly without an internet connection.

## References

- [Building an Offline-First React Application with React Query Library](https://borstch.com/blog/development/building-an-offline-first-react-application-with-react-query-library)
- [Implementing Offline Support with React Hooks and Service Workers](https://www.geeksforgeeks.org/implementing-offline-support-with-react-hooks-and-service-workers/)
- [Building Offline-First Apps with React and IndexedDB](https://www.momentslog.com/development/web-frontend/building-offline-first-apps-with-react-and-indexeddb)