The sync part is what trips you up if you're not thinking about it from the start.
Start by clarifying the requirements and constraints (e.g., real-time expectations, platform, data source) before diving into architecture. Then propose a high-level design that separates data fetching, state management, and UI, and discuss trade-offs of different real-time update strategies. Finally, walk through a concrete implementation plan, highlighting how you would ensure consistency and performance.
Pro tip: Emphasize the importance of a single source of truth for data and discuss how you would handle edge cases like offline support, race conditions, and error states—this shows you think beyond the happy path.
Ask questions to understand the scope: What does 'real time' mean (seconds, milliseconds)? Are the lists independent or related? What platforms and data sources? This ensures you design the right solution.
Decide on a state management approach (e.g., Redux, MobX, Provider, or a shared repository) and a real-time mechanism (WebSockets, polling, Firebase, etc.). Consider trade-offs between complexity, latency, and scalability.
Define how data is fetched, stored, and updated. Ensure both views subscribe to the same data source so changes propagate automatically. Use observers or streams to push updates.
Address potential issues: network failures, conflicting updates, offline mode, and performance with large lists. Describe how you would implement retries, optimistic updates, and conflict resolution.
Recap your solution and discuss alternative approaches (e.g., polling vs. WebSockets) and why you chose your design. Mention any libraries or tools you would use.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.