background-positionを取得するjQueryメソッド。

get_bg_position.js

;(function () {
	$.fn.getBgPosition = function () {
		var $elm = $(this).eq(0);
		var defVal = $elm.css('background-position');
		var positions = {};
		if (defVal) {
			var valAry = defVal.split(' ');
			positions = {
				x: parseInt(valAry[0], 10),
				y: parseInt(valAry[1], 10)
			};
		} else {
			positions = {
				x: parseInt($elm.css('background-position-x')),
				y: parseInt($elm.css('background-position-y'))
			};
		}
		return positions;
	};
}());