(function($) {
    var footer;

    $.fn.extend({
        stickyFooter: function(options) {
            footer = this;

            positionFooter();

            $(window)
              .scroll(positionFooter)
              .resize(positionFooter);

            function positionFooter() {
                var docHeight = $(document.body).height() - $("#sticky-footer-push").height();
                if (docHeight < $(window).height()) {
                    var diff = $(window).height() - docHeight;
                    if (!$("#sticky-footer-push").length > 0) {
                        $(footer).before('<div id="sticky-footer-push"></div>');
                    }
                    $("#sticky-footer-push").height(diff);
                }
            }
        }
    });
})(jQuery);