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Design a News Feed UI
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Asked In
LinkedInAdobeRokuRedditMetaPinterest
Key Challenges
- ·Media-heavy infinite feed with smooth 60fps scrolling
- ·Cursor pagination stability under live inserts/deletes
- ·Optimistic like/comment interactions with safe rollback
- ·Realtime updates without disrupting scroll position
- ·Mobile-first performance on degraded networks
Key Takeaways
- ✓Cursor pagination prevents duplicates/missing items under live inserts.
- ✓Virtualization keeps DOM size bounded, which is key to stable 60fps scrolling.
- ✓Real-time strategy: update counts immediately, but insert new posts via banner to preserve scroll context.
- ✓React Query manages server state + optimistic updates; Zustand manages UI state + offline queue.
- ✓In HLD interviews, clear tradeoff reasoning (not code volume) is what gets scored.
- ✓Stable API/event contracts (IDs, cursors, idempotency) reduce inconsistency during retries and real-time sync.