useref.tsx

export const TimesTable = props => {
  const canvasRef = useRef(null);

  const redraw = () => {
    const canvas = canvasRef.current;
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;
  };

  let viz;
  if (canvasRef.current) {
    const ctx = canvasRef.current.getContext('2d');
    viz = <Viz ctx={ctx} {...props} />;
  }

  return (
    <canvas ref={canvasRef}>
      {viz}
    <canvas>
  );
};