useMemo

useMemo is a React hook that uses memoization to store/cache/remember a value returned from the function provided to it.

The memoization happens by providing a dependency array, as long as all the values in the dependency array remain the same then the hook will return the stored value for that input set.

When they change, it will process and store the new value for memoization.

This is slightly different to useCallback because useCallback will remember the function passed in whereas useMemo will remember the value returned from it.

In React this comes in handy to prevent extra renders, prevent expensive computations, or to prevent duplicate network calls.