var isMobile;
var is_uiwebview = /(iPhone|iPod|iPad).*AppleWebKit(?!.*Safari)/i.test(navigator.userAgent);
var is_safari_or_uiwebview = /(iPhone|iPod|iPad).*AppleWebKit/i.test(navigator.userAgent);
var ua = navigator.userAgent.toLowerCase();
var isAndroid = ua.indexOf( "android") > -1;

if ( isAndroid || is_uiwebview || is_safari_or_uiwebview ) {
  isMobile = true;
	//do something
}