React Routing and Performance 2

Question 1

In React Router v6, which component is used to render the matched child route inside a parent layout component?

Accepted Answer

Answer

<Outlet /> renders the matched nested child route inside a parent route's layout element.

Question 2

Which React Router hook returns the current location object including pathname and search params?

Accepted Answer

useLocation

Answer

useLocation returns the current location object with pathname, search, hash, and state.

Question 3

What does React.memo do to a functional component?

Accepted Answer

Memoizes the rendered output so it skips re-render when props are unchanged

Answer

React.memo performs a shallow props comparison and skips re-rendering when props have not changed.

Question 4

Which hook lets you memoize an expensive computed value between renders?

Accepted Answer

useMemo

Answer

useMemo caches the result of an expensive calculation and recomputes only when dependencies change.

Question 5

What is the primary purpose of useCallback?

Accepted Answer

Return a memoized function reference that stays stable between renders

Answer

useCallback returns a memoized callback whose identity is preserved unless its dependencies change.

React Practice Test