excalidraw/src/is-mobile.tsx

import React, { useState, useEffect, useRef, useContext } from "react";

const context = React.createContext(false);

export const IsMobileProvider = ({
  children,
}: {
  children: React.ReactNode;
}) => {
  const query = useRef<MediaQueryList>();
  if (!query.current) {
    query.current = window.matchMedia
      ? window.matchMedia(
          // keep up to date with _variables.scss
          "(max-width: 640px), (max-height: 500px) and (max-width: 1000px)",
        )
      : (({
          matches: false,
          addListener: () => {},
          removeListener: () => {},
        } as any) as MediaQueryList);
  }
  const [isMobile, setMobile] = useState(query.current.matches);

  useEffect(() => {
    const handler = () => setMobile(query.current!.matches);
    query.current!.addListener(handler);
    return () => query.current!.removeListener(handler);
  }, []);

  return <context.Provider value={isMobile}>{children}</context.Provider>;
};

export default function useIsMobile() {
  return useContext(context);
}