Window: orientationchange event

The orientationchange event is fired when the orientation of the device has changed.

Bubbles	No
Cancelable	No
Interface	Event
Event handler	onorientationchange

You can use the orientationchange event in an addEventListener method:

window.addEventListener("orientationchange", function(event) {
  console.log("the orientation of the device is now " + event.target.screen.orientation.angle);
});

Or use the onorientationchange event handler property:

window.onorientationchange = function(event) {
  console.log("the orientation of the device is now " + event.target.screen.orientation.angle);
};