sS hjs_getOS() {
  ret hjavascript([[
    function getOS() {
      var userAgent = window.navigator.userAgent,
          platform = window.navigator.platform,
          macosPlatforms = ['Macintosh', 'MacIntel', 'MacPPC', 'Mac68K'],
          windowsPlatforms = ['Win32', 'Win64', 'Windows', 'WinCE'],
          iosPlatforms = ['iPhone', 'iPad', 'iPod'],
          os = null;
    
      if (macosPlatforms.indexOf(platform) !== -1) {
        os = 'Mac OS';
      } else if (iosPlatforms.indexOf(platform) !== -1) {
        os = 'iOS';
      } else if (windowsPlatforms.indexOf(platform) !== -1) {
        os = 'Windows';
      } else if (/Android/.test(userAgent)) {
        os = 'Android';
      } else if (!os && /Linux/.test(platform)) {
        os = 'Linux';
      }
    
      return os;
    }
  ]]);
}