$.ajax({ url: '//munchkin.marketo.net/munchkin.js', dataType: 'script', cache: true, success: function() { Munchkin.init('727-ZQE-044'); } }); var parallax = (function(jq){ var $ = jq; function init() { var div = $('#img1'); var nav_div = $('#floatingnav'); function calculate_parallax_height() { var img_w = 3200; var img_h = 1040; var divwidth = div.width(); console.log('div width', divwidth); var newheight = Math.floor((divwidth * img_h) / img_w)-1; console.log('new height', newheight); return newheight; } function resize_all_parallax() { var newheight = calculate_parallax_height(); div.height(newheight + 'px'); var newtop = newheight - 88; //nav_div.top(newtop + 'px'); } $(window).on('resize', function(){ resize_all_parallax(); }); resize_all_parallax(); $(window).on('scroll', function(){ var newheight = calculate_parallax_height(); if (newheight <= $(window).scrollTop()) { // if so, add the fixed class nav_div.addClass('scrolling-nav-top'); } else { // otherwise remove it nav_div.removeClass('scrolling-nav-top'); } }); } return { init: init }; })(jQuery);