Sticky header

Untitled-2

//sticky
$(function() {
  // Hide Header on on scroll down
  var didScroll = false;
  var lastScrollTop = 0;
  var delta = 5;
  var navbarHeight = $('.c-header').outerHeight() + 30;

  if ($(window).scrollTop() == 0) {
    $('.c-header').addClass('js-at-top');
  } else {
    $('.c-header').removeClass('js-at-top');
  }

  $(window).scroll(function(event) {
    didScroll = true;
  });

  setInterval(function() {
    if (didScroll) {
      hasScrolled();
      didScroll = false;
    }
  }, 25);

  function hasScrolled() {
    var scrollLoc = $(this).scrollTop();

    // Make sure they scroll more than delta
    if (Math.abs(lastScrollTop - scrollLoc) <= delta)
      return;

    // If they scrolled down and are past the navbar, add class .js-scroll-up.
    // This is necessary so you never see what is "behind" the navbar.
    if (scrollLoc > lastScrollTop && scrollLoc > navbarHeight) {
      // Scroll Down
      $('.c-header, .c-toc').removeClass('js-scroll-down').addClass('js-scroll-up');
    } else {
      // Scroll Up
      if (scrollLoc + $(window).height() < $(document).height()) {
        $('.c-header, .c-toc').removeClass('js-scroll-up').addClass('js-scroll-down');
      }
    }

    if (scrollLoc == 0) {
      $('.c-header').addClass('js-at-top');
    } else {
      $('.c-header').removeClass('js-at-top');
    }

    lastScrollTop = scrollLoc;
  }
});