Center position with jQuery

center-position.jquery.js

$.fn.centerPosition = function() {
    "use strict";

    var $targets = $(this);

    if (!$targets.length) {
        $targets = $('.centered:visible');
    }

    $targets.each(function() {
        $(this).css('margin-top', 0);
        $(this).css('margin-top', Math.max(0,
            Math.floor(($(this).parent().height() - $(this).outerHeight()) / 2)
        ));
    });

    return $targets;
};