Center Element Based On Another Element

jquery-bootstrap3-subnav-centering.js

// general usage function call: centerElement(selector, target);
// add in: Parent is absolute
// add in: Parent is relative

$("li.dropdown").click(function(event) {
	centerElement( $("ul.dropdown-menu"), $(event.target) );
});

function centerElement(selector, target) {
	var selector = target.next(selector);
	var selectorWidth = selector.outerWidth();
	var targetWidth = target.outerWidth();
	var selectorCenter = Math.abs(selectorWidth / 2) - (targetWidth / 2);

	selector.css({ "margin-left": -1 * selectorCenter });
}