krata/assets/js/_commons/topbar-switch.js

/*
 * Hide Header on scroll down
 * v2.0
 * https://github.com/cotes2020/jekyll-theme-chirpy
 * © 2018-2019 Cotes Chung
 * MIT License
 */

$(function() {

  var didScroll;
  var lastScrollTop = 0;
  var delta = 5;
  var topbarHeight = $("#topbar-wrapper").outerHeight();

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

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

    if (st > lastScrollTop && st > topbarHeight) {
      /* Scroll Down */
      $("#topbar-wrapper").removeClass("topbar-down").addClass("topbar-up");

      if ($("#toc-wrapper").length > 0) {
        $("#toc-wrapper").removeClass("topbar-down");
      }

      if ($(".access").length > 0) {
        $(".access").removeClass("topbar-down");
      }

      if ($("#search-input").is(":focus")) {
        $("#search-input").blur(); /* remove focus */
      }

    } else {
      /* Scroll Up */
      if (st + $(window).height() < $(document).height()) {
        $("#topbar-wrapper").removeClass("topbar-up").addClass("topbar-down");
        if ($("#toc-wrapper").length > 0) {
          $("#toc-wrapper").addClass("topbar-down");
        }
        if ($(".access").length > 0) {
          $(".access").addClass("topbar-down");
        }
      }
    }

    lastScrollTop = st;
  }

  $(window).scroll(function(event) {
    if ($("#topbar-title").is(":hidden")) { /* Not in small screens */
      didScroll = true;
    }
  });

  setInterval(function() {
    if (didScroll) {
      hasScrolled();
      didScroll = false;
    }
  }, 250);

});