Avoid an unstyled rendering moment with the tables of contents

Tables of contents are now statically rendered in their appropriately
open/closed states, rather than updated via JavaScript, so they render
correctly on the first page load. In order to make the "page sections"
table still usable without JS, this adds a stylesheet in a <noscript>
tag that forces the sections into an open state.

config.rb

@@ -58,12 +58,11 @@ before_render do |body, page, _, template_class|
   if current_page.data.table_of_contents &&
      template_class == Middleman::Renderers::RedcarpetTemplate
     markdown = Redcarpet::Markdown.new(Redcarpet::Render::HTML_TOC.new)
-    toc = markdown.render(body).sub(/<ul( |>)/, '<ul class="table-of-contents"\1')
+    fragment = Nokogiri::HTML::DocumentFragment.parse(markdown.render(body))
 
     # The JS API's header names are uniquely large and difficult to break up
     # effectively. We do some post-processing to clean them up.
     if page.start_with?("js-api.")
-      fragment = Nokogiri::HTML::DocumentFragment.parse(toc)
       fragment.css("a code").each do |code|
         code.content = code.content.
           gsub(/^types\.[A-Za-z]+\./, '').
@@ -71,10 +70,18 @@ before_render do |body, page, _, template_class|
           gsub(/^new types\./, 'new ').
           gsub(/\(.+\)$/, '()')
       end
-      toc = fragment.to_html
     end
 
-    current_page.add_metadata(table_of_contents: toc)
+    # Modify the default Markdown table of contents to have overview links and
+    # section classes.
+    fragment.css("li > ul").each do |ul|
+      a = ul.parent.elements.first
+      a.add_class("section")
+      ul.elements.before('<li class="overview"><a>Overview</a></li>')
+      ul.elements.first.elements.first['href'] = a['href']
+    end
+
+    current_page.add_metadata(table_of_contents: fragment.to_html)
     body
   end
 end

helpers/sass_helpers.rb

@@ -52,21 +52,34 @@ module SassHelpers
   end
 
   def documentation_toc
-    _toc_level(data.documentation.toc)
+    _toc_level(nil, data.documentation.toc)
   end
 
-  def _toc_level(links)
-    content_tag(:ul, links.map do |link|
-      children = link[:children]
-      text = link.keys.reject {|k| k == :children}.first
-      href = link[text]
+  def _toc_level(parent_href, links)
+    if parent_href
+      overview = content_tag(:li,
+        content_tag(:a, "Overview", href: parent_href,
+          class: ("selected" if current_page.url == parent_href + ".html")),
+        class: "overview")
+    end
 
-      content_tag(:li, [
-        content_tag(:a, text, href: href,
-          class: ("open selected" if current_page.url.start_with?(href))),
-        (_toc_level(children) if children)
-      ].compact)
-    end)
+    content_tag(:ul, [
+      overview,
+      *links.map do |link|
+        children = link[:children]
+        text = link.keys.reject {|k| k == :children}.first
+        href = link[text]
+
+        content_tag(:li, [
+          content_tag(:a, text, href: href,
+            class: [
+              ("section" if children),
+              ("open selected" if current_page.url.start_with?(href))
+            ].compact.join(" ")),
+          (_toc_level(href, children) if children)
+        ].compact)
+      end
+    ].compact)
   end
 
   # Renders a code example.

source/assets/css/components/_lists.scss

@@ -51,14 +51,15 @@
         width: 100%;
 
         &:hover { background-color: $sl-color--dawn-pink; }
-        &.overview {
-          font-size: $sl-font-size--small;
-          &:not(.selected) { color: transparentize($sl-color--midnight-blue, 0.5); }
-        }
+      }
+
+      li.overview a {
+        font-size: $sl-font-size--small;
+        &:not(.selected) { color: transparentize($sl-color--midnight-blue, 0.5); }
       }
 
       li a {
-        &:not([href]) {
+        &.section {
           &::after {
             content: "▶";
             float: right;
@@ -77,7 +78,7 @@
 
         &.selected {
           font-weight: bold;
-          &[href] { background-color: $sl-color--dawn-pink; }
+          &:not(.section) { background-color: $sl-color--dawn-pink; }
         }
       }
     }

source/assets/css/noscript.scss

@@ -0,0 +1,10 @@
+// Styles that are included only when JavaScript is disabled. These override the
+// default styles to make them work better without JS.
+
+// Make the in-page table of contents fully open by default, since we can't
+// dynamically expand it.
+.page-sections li a.section {
+  &::after { transform: rotate(90deg); }
+  + ul {display: block; }
+}
+

source/assets/js/sass.js

@@ -115,18 +115,11 @@ $(function() {
 
 $(function() {
   $(".sl-c-list-navigation-wrapper--collapsible li > ul")
-      .parent().children("a").each(function() {
-    var overview = $('<li><a class="overview">Overview</a></li>\n');
-    var link = overview.children().first().attr("href", $(this).attr("href"));
-
-    if ($(this).hasClass("selected") &&
-        link[0].pathname == window.location.pathname) {
-      link.addClass("selected");
-    }
-
-    $(this).parent().children("ul").prepend(overview);
-    $(this).removeAttr("href");
-  }).click(function() {
-    $(this).toggleClass("open");
-  });
+      .parent()
+      .children("a")
+      .removeAttr("href")
+      .click(function() {
+        $(this).toggleClass("open");
+        return false;
+      });
 });

source/layouts/layout.haml

@@ -11,6 +11,7 @@
     = stylesheet_link_tag 'https://cdn.jsdelivr.net/npm/docsearch.js@2/dist/cdn/docsearch.min.css'
     = stylesheet_link_tag 'sass'
     = yield_content :css
+    %noscript= stylesheet_link_tag 'noscript'
 
     -# Old version of analytics (https://developers.google.com/analytics/devguides/collection/gajs/).
     :javascript

source/layouts/section_reference.haml

@@ -8,5 +8,5 @@
     - content_for :complementary do
       %h3 Page Sections
 
-      %nav.sl-c-list-navigation-wrapper.sl-c-list-navigation-wrapper--collapsible
+      %nav.page-sections.sl-c-list-navigation-wrapper.sl-c-list-navigation-wrapper--collapsible
         = current_page.metadata[:table_of_contents]