isMobile

var isMobile = {
Android: function() {
return navigator.userAgent.match(/Android/i);
},
BlackBerry: function() {
return navigator.userAgent.match(/BlackBerry/i);
},
iOS: function() {
return navigator.userAgent.match(/iPhone|iPad|iPod/i);
},
Opera: function() {
return navigator.userAgent.match(/Opera Mini/i);
},
Windows: function() {
return navigator.userAgent.match(/IEMobile/i);
},
any: function() {
return (isMobile.Android() || isMobile.BlackBerry() || isMobile.iOS() || isMobile.Opera() || isMobile.Windows());
},
orientation:function(){
return window.neworientation.current;
}
};

if(isMobile.any()) alert('Mobile');
window.addEventListener('orientationchange', function(){
if(window.neworientation.current === 'portrait'){
document.getElementById("body").style.background="red";
} else {
document.getElementById("body").style.background="blue";
}
}, false);