useLayoutEffect

Question 1

How do “useLayoutEffect” & “useEffect” run when you’re about to “npm run dev” an app/web to the screen?

Answer 1

useEffect runs ASYNCHRONOUSLY, AFTER the components have rendered to the screen.

useLayoutEffect runs SYNCHRONOUSLY, BEFORE the components have rendered to the screen.

Question 2

What is useLayoutEffect used for in React?

Answer 2

useLayoutEffect is used to perform side effects that need to occur synchronously after all DOM mutations.

Question 3

True or False: useLayoutEffect runs after the browser has painted the updates.

Answer 3

False

Question 4

Fill in the blank: useLayoutEffect is similar to useEffect, but it fires ________.

Answer 4

synchronously after DOM updates

Question 5

What happens if you call useLayoutEffect with an empty dependency array?

Answer 5

It behaves like componentDidMount and runs only once after the initial render.

Question 6

Which hook should you use for side effects that do not require synchronous execution?

Answer 6

useEffect

Question 7

Multiple Choice: When is useLayoutEffect typically used?
A) To read layout from the DOM and synchronously re-render
B)) To

Answer 7

A) To read layout from the DOM and synchronously re-render

Question 8

What is the signature of useLayoutEffect?

Answer 8

useLayoutEffect(effect: () => void | Cleanup, deps?: DependencyList): void

Question 9

True or False: useLayoutEffect can return a cleanup function.

Answer 9

True

Question 10

What is the main performance consideration when using useLayoutEffect?

Answer 10

It can block visual updates, leading to potential performance issues if not used carefully.

Question 11

Short Answer: Can useLayoutEffect be used for asynchronous operations?

Answer 11

No, useLayoutEffect is meant for synchronous operations.