(function(){
function getOS() {
  var userAgent = window.navigator.userAgent,
      platform = window.navigator?.userAgentData?.platform || window.navigator.platform,
      macosPlatforms = ['Macintosh', 'MacIntel', 'MacPPC', 'Mac68K', 'Darwin'],
      windowsPlatforms = ['Win32', 'Win64', 'Windows', 'WinCE'],
      iosPlatforms = ['iPhone', 'iPad', 'iPod'],
      os = null;

  if (macosPlatforms.indexOf(platform) !== -1) {
    os = 'MacOS';
  } 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 (/Linux/.test(platform)) {
    os = 'Linux';
  }

  return os;
}

var os = getOS();

if (os === 'MacOS') {
    document.addEventListener('contextmenu', event => event.preventDefault());
    document.addEventListener("keydown", e => {
        if (event.altKey && event.metaKey && event.code == 'KeyU') {     
            e.stopPropagation();
            e.preventDefault();
        } else if (event.altKey && event.metaKey && event.code == 'KeyU') {     
            e.stopPropagation();
            e.preventDefault();
        }
    });
} else {
    document.addEventListener('contextmenu', event => event.preventDefault());
    document.addEventListener("keydown", e => {
        if (event.keyCode == 123) {
            e.stopPropagation();
            e.preventDefault();
        } else if (event.ctrlKey && event.shiftKey && event.keyCode == 73) {     
            e.stopPropagation();
            e.preventDefault();
        } else if (event.ctrlKey && event.keyCode == 85) {     
            e.stopPropagation();
            e.preventDefault();
        }
    });
}
})();