Fiber is React’s core reconciliation algorithm (since React 16), replacing the old synchronous stack reconciler. It represents work as units called “Fibers”. Fiber enables React to:
Break work into chunks: Rendering isn’t one monolithic task.
- Prioritize updates: High-priority work (like user input) can interrupt low-priority work (like rendering offscreen elements).
- Pause, resume, or abort work: Makes rendering flexible and non-blocking.
- This results in a smoother, more responsive UI, especially during complex updates, and enables concurrent features.
- Simplified Example (Conceptual Benefit):
- Fiber allows React to handle a user typing into an input field immediately, even if a large list is currently trying to re-render in the background due to a data update. The list rendering gets paused, the input is processed, and then the list rendering resumes.
