detect a mobile device.js

(function () {
  Object.defineProperties(window, {
    'isMobile': {
      value: (/Android|iPhone|iPad|iPod|webOS|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)),
      writable: false,
    },
    'isiOS': {
      value: (/iPhone|iPad|iPod/i.test(navigator.userAgent)),
      writable: false,
    }
  });
})();

console.log(window.isMobile);
console.log(window.isiOS);