qp2/js/main.js

// Dean Attali / Beautiful Jekyll 2016

var main = {

  bigImgEl : null,
  numImgs : null,

  init : function() {
    // 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");
    });
  
    // On mobile, when clicking on a multi-level navbar menu, show the child links
    $('#main-navbar').on("click", ".navlinks-parent", function(e) {
      var target = e.target;
      $.each($(".navlinks-parent"), function(key, value) {
        if (value == target) {
          $(value).parent().toggleClass("show-children");
        } else {
          $(value).parent().removeClass("show-children");
        }
      });
    });
    
    // Ensure nested navbar menus are not longer than the menu header
    var menus = $(".navlinks-container");
    if (menus.length > 0) {
      var navbar = $("#main-navbar ul");
      var fakeMenuHtml = "<li class='fake-menu' style='display:none;'><a></a></li>";
      navbar.append(fakeMenuHtml);
      var fakeMenu = $(".fake-menu");

      $.each(menus, function(i) {
        var parent = $(menus[i]).find(".navlinks-parent");
        var children = $(menus[i]).find(".navlinks-children a");
        var words = [];
        $.each(children, function(idx, el) { words = words.concat($(el).text().trim().split(/\s+/)); });
        var maxwidth = 0;
        $.each(words, function(id, word) {
          fakeMenu.html("<a>" + word + "</a>");
          var width =  fakeMenu.width();
          if (width > maxwidth) {
            maxwidth = width;
          }
        });
        $(menus[i]).css('min-width', maxwidth + 'px')
      });

      fakeMenu.remove();
    }      

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

          // 2fc73a3a967e97599c9763d05e564189
    // set an initial image
    var imgInfo = main.getImgInfo();
    var src = imgInfo.src;
    var desc = imgInfo.desc;
      main.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 = main.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() {
        main.setImg(src, desc);
      img.remove();
        getNextImg();
      }, 1000); 
        //});   
      }, 6000);
      };
    
    // If there are multiple images, cycle through them
    if (main.numImgs > 1) {
        getNextImg();
    }
    }
  },
  
  getImgInfo : function() {
    var randNum = Math.floor((Math.random() * main.numImgs) + 1);
    var src = main.bigImgEl.attr("data-img-src-" + randNum);
  var desc = main.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', main.init);