@react95/gatsby-theme/src/utils/isMobile.js

A React95 theme for your Gatsby blog

const isMobile =
  typeof window !== 'undefined' &&
  (/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(
    navigator.userAgent,
  ) ||
    window.innerWidth < 500);

export default isMobile;