Cards

What does useReducer do?

An alternative to useState for complex state logic, accepts a reducer function and initial state

What is the purpose of useCallback?

Returns a memoized callback function that only changes when dependencies change

When should you use useMemo?

To memoize expensive calculations that only need to recompute when dependencies change

What does useRef return?

A mutable ref object with a .current property that persists across renders

What is useContext used for?

Subscribing to React context without wrapping components in Consumer

How do you run useEffect only once on mount?

Pass an empty dependency array: useEffect(() => {}, [])

When does useEffect run by default?

After every render (initial render and updates)

What does useState return?

An array with two elements: the current state value and a function to update it