gistfile1.js

var $body = $('body');

if (!$body.hasClass('whatever')) {
            var header_wrap = $('#header-wrap');            
            var sticky_navigation_offset_top = header_wrap.offset().top;

            var sticky_navigation = function() {
                var scroll_top = $(window).scrollTop();

                if (scroll_top > sticky_navigation_offset_top) {
                    header_wrap.addClass('sticky-nav');
                    $body.addClass('scrolled');
                }
                else {
                    header_wrap.removeClass('sticky-nav');
                    $body.removeClass('scrolled');
                }
            };
}