React Hooks Javascript 2

Question 1

What does the useState hook return?

Accepted Answer

An array with the state value and a setter function

Answer

A single state object

Answer

Only the state value

Answer

A promise that resolves to the state

Question 2

Which hook lets you perform side effects in a function component?

Accepted Answer

useEffect

Answer

useState

Answer

useMemo

Answer

useRef

Question 3

When does an effect with an empty dependency array `[]` run?

Accepted Answer

Only once after the initial mount

Answer

After every render

Answer

Never

Answer

Before every render

Question 4

What is the purpose of the cleanup function returned by useEffect?

Accepted Answer

To run before the component unmounts or before re-running the effect

Answer

To reset all state

Answer

To delete the component

Answer

To trigger a re-render

Question 5

Which hook returns a mutable object whose `.current` persists across renders without causing re-renders?

Accepted Answer

useRef

Answer

useState

Answer

useReducer

Answer

useContext

Question 6

What rule governs where Hooks can be called?

Accepted Answer

Only at the top level of a component or custom hook

Answer

Only inside loops

Answer

Anywhere in the file

Answer

Only inside event handlers

Question 7

Which hook is preferred for managing complex state logic with multiple sub-values?

Accepted Answer

useReducer

Answer

useState

Answer

useEffect

Answer

useCallback