접속 기기 알아내기

var currentOS;
var mobile = (/iphone|ipad|ipod|android/i.test(navigator.userAgent.toLowerCase()));

if (mobile) {
  var userAgent = navigator.userAgent.toLowerCase();
  
  if (userAgent.search("android") > -1)
    currentOS = "android";
  else if ((userAgent.search("iphone") > -1) || (userAgent.search("ipod") > -1) || (userAgent.search("ipad") > -1))
    currentOS = "ios";
  else
    currentOS = "else";
} else {
  // 모바일이 아닐 때
  currentOS = "nomobile";
}

참고

• https://koreaparks.tistory.com/135
• render-a-different-html-page-for-requests-from-mobile-device-using-only-html-css