If there is no element with "navbar" class, the original code would cause an error when I scroll the screen because $(."navbar").offset() is null. //jQuery to collapse the navbar on scroll $(window).scroll(function () { if ($(".navbar").offset().top > 50) { $(".navbar-fixed-top").addClass("top-nav-collapse"); } else { $(".navbar-fixed-top").removeClass("top-nav-collapse"); } To fix this I put everything in the function inside the following if and the error is gone now. Please check . /*bug fix */ if($(".navbar").offset()){} /*bug fix*/ }); I am considering buying a corporate license and this kind of issue concerns me. Thanks Don

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