Callback hook

Returns a memoized callback.

Pass an inline callback and an array of dependencies.

useCallback will return a memoized version of the callback that only changes if one of the dependencies has changed.

This is useful when passing callbacks to optimized child components that rely on reference equality to prevent unnecessary renders (e.g. shouldComponentUpdate).

Compare with useMemo - these are equivalent:

useCallback(fn, deps)

useMemo(() => fn, deps)