Technologies Coding Problems Bookmarks Learning Paths

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How does React Fiber handle errors? | Reconciliation | react Interview Questions | NextRound.in

Questions

13 of 13

1What is reconciliation in React?

2What is react fibre?

3What is fibre in react fiber?

4Discuss fibre lifecycle.

5Discuss stack reconciler.

6What is concurrent rendering in react?

7How does React Fiber improve the rendering performance?

8What is the purpose of the `dangerouslySetInnerHTML` attribute in React?

9When rendering a list what is a key and what is its purpose?

10What are low and high-priority updates?

11What is work in progress tree in react fibre?

12Is React Fiber backward compatible with previous versions of React?

13How does React Fiber handle errors?

react

State and Props

Class Components

Function Components

Lifecycle functions

Performance Optimisation

13 / 13

How does React Fiber handle errors?

Difficulty: 6/10

error boundaries, fiber reconciliation, suspense

React Fiber introduces a new error-handling mechanism called Error Boundaries, which allows developers to catch errors in the component tree and display a fallback UI. Error Boundaries are components that implement the componentDidCatch method or use the static getDerivedStateFromError method. When an error occurs within a component tree, React will look for the nearest Error Boundary and delegate error handling to it, preventing the entire application from crashing.

Scenario Questions

0-2 years experience

1If a child component throws an exception while rendering, what does React Fiber do and how would you prevent the whole app from crashing?
2Show me how you would add an error boundary around a small widget so that a rendering error only hides that widget, not the rest of the page.

2-5 years experience

1During a feature rollout a third‑party library throws inside a useEffect. The page crashes even though you have a top‑level error boundary. Walk me through why Fiber didn't catch it and how you would fix it.

Follow-up Questions

What happens if no error boundary is found in the tree?
How does the presence of multiple nested error boundaries affect where the error is handled?
Can you log the error stack from inside getDerivedStateFromError, and why might you choose componentDidCatch instead?

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2You notice that a component wrapped in Suspense throws a network error and the fallback never appears. Explain how Fiber propagates that error and what changes you’d make to handle it gracefully.

5-8 years experience

1Design an error‑handling strategy for a large application that mixes many nested Suspense and error boundaries. How would you decide where to place boundaries to minimize UI disruption and ensure proper logging?
2Compare the trade‑offs of putting a single error boundary at the root versus adding per‑feature error boundaries. Discuss the impact on Fiber's error propagation and any performance considerations.

8+ years experience

1Your organization is migrating a legacy codebase that uses try/catch in componentWillMount for error handling. How would you refactor the code to leverage Fiber’s error boundaries while keeping behavior consistent across many teams?
2We have several micro‑frontends that share a common React root. How would you evolve the error‑handling architecture across these teams, considering Fiber’s error propagation model and the need for unified logging and recovery?