What are the advantages of Custom Hooks?

0-2 years experience

1. 1You need to fetch the current user's profile in two separate components. How would you use a custom hook to avoid duplicating the fetch logic?
2. 2If you move form field handling into a custom hook, what happens to the component's state and its re‑render behavior?
3. 3Suppose the custom hook you wrote should accept a URL parameter to fetch different resources. How would you design that API?

2-5 years experience

1. 1We have a component that uses a custom hook for a debounced search, and after a recent refactor the search no longer triggers. How would you debug the problem?
2. 2When choosing between a custom hook and a higher‑order component for sharing logic, what trade‑offs do you consider?
3. 3Explain how you would structure a custom hook that manages a WebSocket connection used by multiple components, and why that design is beneficial.

5-8 years experience

1. 1Our dashboard renders hundreds of widgets, each using a custom hook for data polling, and we’re seeing performance degradation. How would you evaluate and improve the hook’s design?
2. 2Describe how you would enforce consistent error handling and loading states across the app using a shared custom hook, and what architectural implications that brings.
3. 3If a custom hook’s useEffect depends on an object prop, what pitfalls could arise at scale and how would you mitigate them?

8+ years experience

1. 1We plan to migrate a large legacy codebase to use custom hooks for all side‑effects. What rollout strategy would you propose to coordinate across multiple teams while minimizing risk?
2. 2Discuss the long‑term maintenance considerations of exposing a library of custom hooks as a shared package across several products. How would you handle versioning and deprecation?
3. 3How would you design a custom‑hook framework that lets teams plug in their own implementations (e.g., analytics) without breaking existing components?