beautifulSA-jekyll/assets/js/beautifuljekyll.js

// Dean Attali / Beautiful Jekyll 2020

var BeautifulJekyllJS = {

  bigImgEl : null,
  numImgs : null,

  init : function() {
    setTimeout(BeautifulJekyllJS.initNavbar, 10);

    // Shorten the navbar after scrolling a little bit down
    $(window).scroll(function() {
        if ($(".navbar").offset().top > 50) {
            $(".navbar").addClass("top-nav-short");
        } else {
            $(".navbar").removeClass("top-nav-short");
        }
    });

    // On mobile, hide the avatar when expanding the navbar menu
    $('#main-navbar').on('show.bs.collapse', function () {
      $(".navbar").addClass("top-nav-expanded");
    });
    $('#main-navbar').on('hidden.bs.collapse', function () {
      $(".navbar").removeClass("top-nav-expanded");
    });

    // show the big header image
    BeautifulJekyllJS.initImgs();
  },

  initNavbar : function() {
    // Set the navbar-dark/light class based on its background color
    const rgb = $('.navbar').css("background-color").replace(/[^\d,]/g,'').split(",");
    const brightness = Math.round(( // http://www.w3.org/TR/AERT#color-contrast
      parseInt(rgb[0]) * 299 +
      parseInt(rgb[1]) * 587 +
      parseInt(rgb[2]) * 114
    ) / 1000);
    if (brightness <= 125) {
      $(".navbar").removeClass("navbar-light").addClass("navbar-dark");
    }
  },

  initImgs : function() {
    // If the page was large images to randomly select from, choose an image
    if ($("#header-big-imgs").length > 0) {
      BeautifulJekyllJS.bigImgEl = $("#header-big-imgs");
      BeautifulJekyllJS.numImgs = BeautifulJekyllJS.bigImgEl.attr("data-num-img");

      // 2fc73a3a967e97599c9763d05e564189
      // set an initial image
      var imgInfo = BeautifulJekyllJS.getImgInfo();
      var src = imgInfo.src;
      var desc = imgInfo.desc;
      BeautifulJekyllJS.setImg(src, desc);

      // For better UX, prefetch the next image so that it will already be loaded when we want to show it
      var getNextImg = function() {
        var imgInfo = BeautifulJekyllJS.getImgInfo();
        var src = imgInfo.src;
        var desc = imgInfo.desc;

        var prefetchImg = new Image();
        prefetchImg.src = src;
        // if I want to do something once the image is ready: `prefetchImg.onload = function(){}`

        setTimeout(function(){
          var img = $("<div></div>").addClass("big-img-transition").css("background-image", 'url(' + src + ')');
          $(".intro-header.big-img").prepend(img);
          setTimeout(function(){ img.css("opacity", "1"); }, 50);

          // after the animation of fading in the new image is done, prefetch the next one
          //img.one("transitioned webkitTransitionEnd oTransitionEnd MSTransitionEnd", function(){
          setTimeout(function() {
            BeautifulJekyllJS.setImg(src, desc);
            img.remove();
            getNextImg();
          }, 1000);
          //});
        }, 6000);
      };

      // If there are multiple images, cycle through them
      if (BeautifulJekyllJS.numImgs > 1) {
        getNextImg();
      }
    }
  },

  getImgInfo : function() {
    var randNum = Math.floor((Math.random() * BeautifulJekyllJS.numImgs) + 1);
    var src = BeautifulJekyllJS.bigImgEl.attr("data-img-src-" + randNum);
    var desc = BeautifulJekyllJS.bigImgEl.attr("data-img-desc-" + randNum);

    return {
      src : src,
      desc : desc
    }
  },

  setImg : function(src, desc) {
    $(".intro-header.big-img").css("background-image", 'url(' + src + ')');
    if (typeof desc !== typeof undefined && desc !== false) {
      $(".img-desc").text(desc).show();
    } else {
      $(".img-desc").hide();
    }
  }
};

// 2fc73a3a967e97599c9763d05e564189

document.addEventListener('DOMContentLoaded', BeautifulJekyllJS.init);