React Fiber is the reimplementation of React’s core reconciliation algorithm, introduced in React 16 (2017).
It replaced the old React stack algorithm to improve performance and user experience, especially for complex UIs.
What is Reconciliation?
- Reconciliation is the process React uses to update the DOM when a component’s state or props change.
- React compares the Virtual DOM with the previous version and makes the minimum number of updates to the actual DOM.
What is React Fiber?
React Fiber is a complete rewrite of React’s reconciliation algorithm, designed to make rendering more flexible and efficient.
Fiber introduced the concept of incremental rendering, which breaks rendering work into small units and spreads it over multiple frames, instead of blocking the main thread.
Key Improvements with React Fiber:
| Feature | Description |
|---|---|
| Incremental Rendering | Splits work into chunks and pauses when needed, improving UI responsiveness. |
| Better Performance | Handles large and complex applications more efficiently. |
| Prioritization | Prioritizes important updates (e.g., user interactions) over less important ones. |
| Concurrency | Lays the foundation for concurrent features like Concurrent Mode and Suspense. |
| Error Handling | Introduced Error Boundaries for better error management in components. |
| Animation-friendly | Improves rendering performance for animations, gestures, and transitions. |
How React Fiber Works:
Fiber introduces two phases in rendering:
| Phase | Description |
|---|---|
| Render Phase | Work is split into units and can be interrupted if needed. |
| Commit Phase | DOM is updated in a single, fast step (synchronous). |
Why React Fiber is Important:
| Importance | Explanation |
|---|---|
| Improves User Experience | Faster, more responsive apps (especially for large UIs). |
| Enables Concurrent Mode | Smooth UI updates and non-blocking rendering. |
| Better Handling of Complex UIs | Complex updates are managed efficiently without blocking the UI. |
| Foundation for Future React Features | Supports features like Suspense, Concurrent Rendering, and React 18 advancements. |
| Smooth Animations & Gestures | Improved scheduling system for better visual experiences. |
React Features Enabled by Fiber:
| Feature | Description |
|---|---|
| Concurrent Mode | Improves rendering responsiveness with background rendering. |
| Suspense | Handles loading states more smoothly. |
| Transitions | Improves page transitions and complex UI updates. |
Final Summary:
✅ React Fiber is a new core algorithm introduced in React 16.
✅ Improves performance, prioritizes updates, and enables concurrent rendering features.
✅ Lays the groundwork for modern React features like Concurrent Mode, Suspense, and Smooth Animations.
✅ Makes React applications faster, smoother, and more interactive. 🚀
