landscape && landscape (ok)

function doOnOrientationChange() {
    switch(window.orientation) {  
      case -90: case 90:
        alert('landscape');
        break; 
      default:
        alert('landscape');
        break; 
    }
}
  
window.addEventListener('orientationchange', doOnOrientationChange);
  
// Initial execution if needed
doOnOrientationChange();

https://stackoverflow.com/questions/5284878/how-do-i-correctly-detect-orientation-change-using-phonegap-on-ios