Javascript function to check if an element and/or its parents position is set to fixed

isPositionFixed

isPositionFixed = function (selector, traverseAncestors) {
	var el = $(selector);
	if (el.length) {
		if (!traverseAncestors) {
			return 'fixed' === el.css('position') ? true : false ;
		}
		var isFixed = false;
		var els = el.add(el.parents());
		els.each(function() {
			if ('fixed' === $(this).css('position')) {
				isFixed = true;
				return false;
			}
		});
		return isFixed;
	}
}