React

Question 1

What is JSX?

Answer 1

Templating language that lets you write HTML-like UI code with JavaScript

Question 2

What is the virtual DOM?

Answer 2

Intermediary layer that tracks changes to the actual dom and let’s React only rerender the parts taht have changed rather than the whole page.

Question 3

What are useCallback and useMemo used for?

Answer 3

useCallback is for memoizing functions, and useMemo is for memoizing any value such as an array.

You should only use either hook when you either need to:
1. Cache heavy computations
2. Check referential equality, ex. dependency arrays for other hooks like useEffect

Question 4

What is useRef used for?

Answer 4

Can be used to store a value that doesn’t cause re-renders wehn changed.
It is usually used to keep reference to a specific component in the view tree, so that you can access it later.
const ref = useRef()
<Button ref={ref}/>

Question 5

What is Context used for?

Answer 5

Storing values that will be widely needed by many or most sub-components. Allows you to avoid prop drilling. Can be replaced by other state management tools like redux or recoil

Often used themes or light/dark mode