Ref Callback Cleanup

ref Cleanup Functions

The Shift: When using a "Callback Ref" (a function passed to ref instead of a useRef object), you couldn't easily clean up side effects when the element was removed. React 19 allows you to return a cleanup function, exactly like useEffect.

👀 Preview

When the element is removed, the cleanup function automatically runs, disconnecting the observer.

📚 Explanation

Ref callbacks in React 19 can return a cleanup function, similar to `useEffect`. This cleanup function is called when the element is removed from the DOM, making it easy to clean up observers, event listeners, or other side effects.