Add user agent classes

ua-classes.js

// Add user agent classes
(function() {
  var ua = navigator.userAgent,
      d = document.documentElement,
      classes = d.className;

  // Replace 'no-js' class name with 'js'
  classes = classes.replace('no-js','js');

  // Detect iOS (needed to disable zoom on form elements)
  // http://stackoverflow.com/questions/9038625/detect-if-device-is-ios/9039885#9039885
  if ( /iPad|iPhone|iPod/.test(ua) && !window.MSStream ) {
    classes += ' ua-ios';

    // Add class for version of iOS
    var matches = ua.match(/((\d+_?){2,3})\slike\sMac\sOS\sX/);
    if ( matches ) {
      classes += ' ua-ios-' + matches[1];// e.g. ua-ios-7_0_2
    }

    // Add class for Twitter app
    if ( /Twitter/.test(ua) ) {
      classes += ' ua-ios-twitter';
    }

    // Add class for Chrome browser
    if ( /CriOS/.test(ua) ) {
      classes += ' ua-ios-chrome';
    }
  }

  // Detect Android (needed to disable print links on old devices)
  // http://www.ainixon.me/how-to-detect-android-version-using-js/
  if ( /Android/.test(ua) ) {
    var matches = ua.match(/Android\s([0-9\.]*)/);
    classes += matches ? ' ua-aos ua-aos-' + matches[1].replace(/\./g,'_') : ' ua-aos';
  }

  // Detect webOS (needed to disable optimizeLegibility)
  if ( /webOS|hpwOS/.test(ua) ) {
    classes += ' ua-webos';
  }

  // Detect Samsung Internet browser
  if ( /SamsungBrowser/.test(ua) ) {
    classes += ' ua-samsung';
  }

  // Add classes
  d.className = classes;
})();