Hooks Interview Questions

useEffect with an empty dependency array replaces componentDidMount. With a dependency array it replaces componentDidUpdate for specific values. With a cleanup return it replaces componentWillUnmount. React.memo replaces shouldComponentUpdate. useLayoutEffect replaces getSnapshotBeforeUpdate.

Custom hooks extract stateful logic into reusable functions. The use prefix enforces Rules of Hooks via the linter. Return a named object, not a tuple, for non-breaking extensibility. Add AbortController cleanup to prevent race conditions when the URL dependency changes.

Understand the key differences between functional and class components, why hooks changed everything, and why functional components are now the standard.

Understand what hooks are, the rules that govern them, and how useState and useEffect replace class component state and lifecycle methods.