Return width and height of viewport

screenDimensions.js

// Get screen dimensions
// http://stackoverflow.com/questions/18546067/why-is-the-window-width-smaller-than-the-viewport-width-set-in-media-queries
var screenDimensions = function() {
	var e = window, a = 'inner';
	if (!('innerWidth' in window )) {
		a = 'client';
		e = document.documentElement || document.body;
	}
	return { width : e[ a+'Width' ] , height : e[ a+'Height' ] };
}