Some of the apps you develop will need to be able to detect whether the mobile device is in portrait (vertical) or landscape (horizontal) orientation. You can use the window.onresize event to detect...

portrait (vertical) or landscape (horizontal) orientation. You can use the window.onresize event

to detect orientation changes. Add a listener for this event and turn the square into a rectangle

when the device is moved into landscape orientation. Turn it back into a square when the device

returns to portrait orientation.