React Hooks useState Hook

Question 1

What does the useState hook return?

Accepted Answer

An array with a state value and a setter function

Answer

A single value

Answer

An object with get and set methods

Answer

A Promise

Question 2

What is the initial value passed to useState used for?

Accepted Answer

It sets the state only on the first render

Answer

It is re-evaluated on every render

Answer

It overrides state on every render

Answer

It is ignored after the component mounts

Question 3

Which of the following correctly initializes a counter state to 0?

Accepted Answer

const [count, setCount] = useState(0)

Answer

const count = useState(0)

Answer

const [count] = useState(0)

Answer

const {count, setCount} = useState(0)

Question 4

What happens if you call the setter function returned by useState with the same value as the current state?

Accepted Answer

React bails out of the re-render

Answer

React always re-renders

Answer

React throws an error

Answer

React resets to the initial value

Question 5

How do you update state based on the previous state value?

Accepted Answer

setCount(prev => prev + 1)

Answer

setCount(count + 1)

Answer

setCount(this.state.count + 1)

Answer

setCount(useState.prev + 1)

Question 6

Which of these is a valid way to lazily initialize state?

Accepted Answer

useState(() => expensiveComputation())

Answer

useState(expensiveComputation)

Answer

useState.lazy(expensiveComputation)

Answer

useLazyState(expensiveComputation)