useSize.tsx

import React from "react";
import useResizeObserver from "./useResizeObserver";

export const useSize = (target: React.RefObject<HTMLElement>) => {
  const [size, setSize] = React.useState<DOMRectReadOnly>();

  React.useLayoutEffect(() => {
    setSize(target.current?.getBoundingClientRect());
  }, [target]);

  // Where the magic happens
  useResizeObserver(target, (entry) => setSize(entry.contentRect));
  return size;
};