readyornot/components/windowsize.tsx

import { useEffect, useState } from "react";

interface ScreenSize {
  width: number | undefined;
  height: number | undefined;
}

export default function useWindowSize(): boolean | undefined {
  const [windowSize, setWindowSize] = useState<ScreenSize>({
    width: undefined,
    height: undefined,
  });

  useEffect(() => {
    function handleResize() {
      setWindowSize({
        width: window.innerWidth,
        height: window.innerHeight,
      });
    }
    
    window.addEventListener("resize", handleResize);

    handleResize();

    return () => window.removeEventListener("resize", handleResize);
  }, []);
  if(typeof(windowSize.width) === "number") {
    return windowSize.width <= 1080;
  }
  else {
    return undefined;
  }
}