Learn mobile device width by its orientation.

mobile-width.js

window.info = function() {
	var i = '';
	i += 'screen.width =' + screen.width + '\n';
	i += 'screen.height =' + screen.height + '\n';
	i += 'window.orientation =' + window.orientation + '\n';
	i += 'window.getWidth() =' + window.getWidth() + '\n';
	alert(i);
};//window.info
	
window.getWidth = function() {
	if(typeof window.orientation == "undefined") return document.body.clientWidth;
	
	var angle = Math.abs(window.orientation % 180);
	switch(angle) {
		case 0:
			return screen.width;
			break;
		case 90:
			return screen.height;
			break;
	}
};//window.getWidth