React Hooks Building React App 3

Question 1

When building a form, which hook tracks the input field's current value?

Accepted Answer

useState

Answer

useMemo

Answer

useReducer for single fields only

Answer

useCallback

Question 2

How do you make an input a controlled component in React?

Accepted Answer

Set value and onChange props

Answer

Use only defaultValue

Answer

Add a ref alone

Answer

Use document.getElementById

Question 3

Which hook is best for fetching data when the App component first mounts?

Accepted Answer

useEffect with an empty dependency array

Answer

useState

Answer

useRef

Answer

useContext

Question 4

What should a data-fetching useEffect return to avoid memory leaks?

Accepted Answer

A cleanup function

Answer

A new component

Answer

The fetched data

Answer

A boolean

Question 5

To display a list of items from state, which approach is used in JSX?

Accepted Answer

Array.map returning elements with keys

Answer

A for loop directly in JSX

Answer

while loop inline

Answer

forEach returning JSX

Question 6

Why must list items rendered with map include a key prop?

Accepted Answer

To help React identify changed items efficiently

Answer

For CSS styling

Answer

To set the index

Answer

It is optional and unused

Question 7

When lifting state up, where should shared state live?

Accepted Answer

In the closest common parent component

Answer

In each child separately

Answer

In a CSS file

Answer

In the index.html