var previousOrientation = window.orientation;
var checkOrientation = function(){
if(window.orientation !== previousOrientation){
previousOrientation = window.orientation;
// orientation changed, do your magic here
}
};
window.addEventListener("resize", checkOrientation, false);
window.addEventListener("orientationchange", checkOrientation, false);
// (optional) Android doesn't always fire orientationChange on 180 degree turns
setInterval(checkOrientation, 2000);