In Chrome Dev Tools: If you go to Settings>Overrides>Device metrics
If you swap the dimensions for the screen resolution the orientation will change and the orientationchange-event will be triggered.
The orientation is depending on the relationship between ‘width’ and ‘height’. If ‘height’ has a higher value than ‘width’, the browser will be in orientation: ‘portrait’
and vice versa.
height > width = portrait
height < width = landscape