Uses JavaScript to check if the device accessing the system is mobile one and, if so, which OS (Android, IOS, etc ...)

checkMobile.js

const isMobile = {
  getUserAgent: function() {
    return navigator.userAgent;
  },
  Android: function() {
    return /Android/i.test(isMobile.getUserAgent()) && !isMobile.Windows();
  },
  BlackBerry: function() {
    return /BlackBerry|BB10|PlayBook/i.test(isMobile.getUserAgent());;
  },
  iPhone: function() {
    return /iPhone/i.test(isMobile.getUserAgent()) && !isMobile.iPad() && !isMobile.Windows();
  },
  iPod: function() {
    return /iPod/i.test(isMobile.getUserAgent());
  },
  iPad: function() {
    return /iPad/i.test(isMobile.getUserAgent());
  },
  iOS: function() {
    return (isMobile.iPad() || isMobile.iPod() || isMobile.iPhone());
  },
  Opera: function() {
    return /Opera Mini/i.test(isMobile.getUserAgent());
  },
  Windows: function() {
    return /Windows Phone|IEMobile|WPDesktop/i.test(isMobile.getUserAgent());
  },
  KindleFire: function() {
    return /Kindle Fire|Silk|KFAPWA|KFSOWI|KFJWA|KFJWI|KFAPWI|KFAPWI|KFOT|KFTT|KFTHWI|KFTHWA|KFASWI|KFTBWI|KFMEWI|KFFOWI|KFSAWA|KFSAWI|KFARWI/i.test(isMobile.getUserAgent());
  },
  any: function() {
    return (isMobile.Android() || isMobile.BlackBerry() || isMobile.iOS() || isMobile.Opera() || isMobile.Windows());
  }
};