Question 1

What is React Context?

Accepted Answer

A way to pass data through the tree without prop drilling via Provider + useContext. Good for theme, locale, auth session. Not a full replacement for complex server cache.

Question 2

Why can context cause wide re-renders?

Accepted Answer

All consumers re-render when the Provider value changes by reference. Split contexts, memoize value, or use selectors/external stores for fine-grained subscriptions.

Question 3

How do you memoize a context value correctly?

Accepted Answer

useMemo the object/functions provided, with correct deps. Recreating {user, setUser } each render defeats consumers' memoization.

Question 4

Context vs Redux/Zustand?

Accepted Answer

Context is built-in DI for relatively stable values; dedicated stores handle high-frequency updates better. Many apps mix: context for DI, Zustand/Query for state/cache.

Question 5

Pattern: separate StateContext and DispatchContext — why?

Accepted Answer

Consumers that only dispatch don't re-render when state changes. Classic performance pattern with useReducer + dual providers.

Question 6

Pitfall: providing a new context default object.

Accepted Answer

Default values are only used without a Provider; mutating defaults is bad; usually require a Provider. Throw in useX() if missing provider for clearer DX.

Context React Interview Questions

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