Q2: What is React Fiber and how does it improve application responsiveness?
React Fiber is the re-implementation of React's core reconciliation algorithm introduced in React 16. It breaks rendering work into incremental units of work called Fiber nodes, enabling React to pause, resume, assign priority to, or abandon work as higher-priority user inputs arrive.
Fiber Priority Work Scheduler
Priority Work Interruption Model
// Fiber tree structure snippet (Internal React Node Representation)
const fiberNode = {
type: 'div',
child: childFiberNode,
sibling: siblingFiberNode,
return: parentFiberNode,
pendingProps: nextProps,
lanes: PriorityLanes // Tracks execution priority
};💡 Fiber nodes use child, sibling, and return pointers to traverse trees iteratively without locking the JS call stack.
Key Takeaways
- Replaces synchronous stack reconciliation with asynchronous cooperative scheduling.
- Enables time-slicing and priority-based scheduling for smooth 60fps user interactions.
Knowledge Check
Which phase of Fiber execution is interruptible by higher-priority tasks?