@primer/components/lib-esm/hooks/useResizeObserver.js

Primer react components

import useLayoutEffect from '../utils/useIsomorphicLayoutEffect';
export function useResizeObserver(callback) {
  useLayoutEffect(() => {
    const observer = new window.ResizeObserver(() => callback());
    observer.observe(document.documentElement);
    return () => {
      observer.disconnect();
    };
  }, [callback]);
}