List all the hooks available in react js and provide brief definition for each

It is a lightweight in-memory representation of the actual DOM to track changes in the UI and efficiently update the real DOM when necessary.

1
useState: to add and manage state to functional components
2
useReducer: to add and manage complex state
3
useEffect: to execute side effects during rendering and hooking into lifecycle hooks
4
useMemo: to memoise the output of a function
5
useCallback: to memoise a function declaration when a function is passed to children components that are memoised.
6
useContext: to access context object
7
useLayoutEffect: synchronously useEffect
8
useRef: to access and manipulate DOM and store values that do not cause rerender on updates.
9
use
10
useDebugValue
11
useId
12
useDeferredValue
13
useTransition
14
useSyncExternalStore
15
useInsertionEffect
16
useImperativeHandle

Difficulty: 6/10

Topics: React Hooks, State Management, Performance

0-2 years experience

1
How would you add a piece of local state to a functional component that toggles a modal open and closed? Which hook would you use and why?
2
If you need to run some code once after a component mounts to fetch initial data, which hook would you choose and what would the dependency array look like?
3
What happens if you call a hook conditionally inside an if statement? Explain the rule that prevents that.

2-5 years experience

1
You have a component that fetches user data in useEffect, but it keeps refetching on every render. Walk me through how you'd debug the dependency array.
2
When would you prefer useReducer over useState for managing form state in a medium‑sized feature? Discuss trade‑offs.
3
Explain how you would create a custom hook to share a WebSocket connection across multiple components, and how you'd handle cleanup.

5-8 years experience

1
A list component suffers from unnecessary re‑renders because a callback prop changes on each render. How would you use hooks to mitigate this and what are the performance implications?
2
You need to expose an imperative method (e.g., focus) from a child functional component to its parent. Which hook would you use and how would you implement it?
3
Describe how you would refactor a large class‑based component that uses lifecycle methods into a functional component using hooks, ensuring behavior stays identical.

8+ years experience

1
Your organization is migrating a legacy codebase of 200+ class components to hooks. What strategy would you propose to do this incrementally while minimizing risk?
2
How would you design a shared state solution across many unrelated parts of the app using hooks, and what are the considerations for scalability and testing?
3
When introducing a new custom hook library across multiple teams, what guidelines and patterns would you establish to keep the API stable and avoid hook misuse?