Back to Top Links in Header Toc Mode

_includes/anchor_headings.html

@@ -0,0 +1,106 @@
+{% capture headingsWorkspace %}
+  {% comment %}
+    Version 1.0.3
+      https://github.com/allejo/jekyll-anchor-headings
+
+    "Be the pull request you wish to see in the world." ~Ben Balter
+
+    Usage:
+      {% include anchor_headings.html html=content %}
+
+    Parameters:
+      * html          (string) - the HTML of compiled markdown generated by kramdown in Jekyll
+
+    Optional Parameters:
+      * beforeHeading (bool)   : false  - Set to true if the anchor should be placed _before_ the heading's content
+      * anchorBody    (string) :  ''    - The content that will be placed inside the anchor; the `%heading%` placeholder is available
+      * anchorClass   (string) :  ''    - The class(es) that will be used for each anchor. Separate multiple classes with a space
+      * anchorTitle   (string) :  ''    - The `title` attribute that will be used for anchors
+      * h_min         (int)    :  1     - The minimum header level to build an anchor for; any header lower than this value will be ignored
+      * h_max         (int)    :  6     - The maximum header level to build an anchor for; any header greater than this value will be ignored
+      * bodyPrefix    (string) :  ''    - Anything that should be inserted inside of the heading tag _before_ its anchor and content
+      * bodySuffix    (string) :  ''    - Anything that should be inserted inside of the heading tag _after_ its anchor and content
+      * linkOverride  (string) :  ''    - An optional override for the inserted anchor hrefs, allowing to use them as back-to-top links instead
+
+    Output:
+      The original HTML with the addition of anchors inside of all of the h1-h6 headings.
+  {% endcomment %}
+
+  {% assign minHeader = include.h_min | default: 1 %}
+  {% assign maxHeader = include.h_max | default: 6 %}
+  {% assign beforeHeading = include.beforeHeading %}
+  {% assign linkOverride = include.linkOverride %}
+  {% assign nodes = include.html | split: '<h' %}
+
+  {% capture edited_headings %}{% endcapture %}
+
+  {% for _node in nodes %}
+    {% capture node %}{{ _node | strip }}{% endcapture %}
+
+    {% if node == "" %}
+      {% continue %}
+    {% endif %}
+
+    {% assign nextChar = node | replace: '"', '' | strip | slice: 0, 1 %}
+    {% assign headerLevel = nextChar | times: 1 %}
+
+    <!-- If the level is cast to 0, it means it's not a h1-h6 tag, so let's try to fix it -->
+    {% if headerLevel == 0 %}
+      {% if nextChar != '<' and nextChar != '' %}
+        {% capture node %}<h{{ node }}{% endcapture %}
+      {% endif %}
+
+      {% capture edited_headings %}{{ edited_headings }}{{ node }}{% endcapture %}
+      {% continue %}
+    {% endif %}
+
+    {% assign _workspace = node | split: '</h' %}
+    {% assign _idWorkspace = _workspace[0] | split: 'id="' %}
+    {% assign _idWorkspace = _idWorkspace[1] | split: '"' %}
+    {% assign html_id = _idWorkspace[0] %}
+
+    {% capture _hAttrToStrip %}{{ _workspace[0] | split: '>' | first }}>{% endcapture %}
+    {% assign header = _workspace[0] | replace: _hAttrToStrip, '' %}
+
+    <!-- Build the anchor to inject for our heading -->
+    {% capture anchor %}{% endcapture %}
+
+    {% if html_id and headerLevel >= minHeader and headerLevel <= maxHeader %}
+      {% if linkOverride %}
+        {% capture anchor %}href="{{linkOverride}}"{% endcapture %}
+      {% else %}
+        {% capture anchor %}href="#{{ html_id}}"{% endcapture %}
+      {% endif %}
+
+      {% if include.anchorClass %}
+        {% capture anchor %}{{ anchor }} class="{{ include.anchorClass }}"{% endcapture %}
+      {% endif %}
+
+      {% if include.anchorTitle %}
+        {% capture anchor %}{{ anchor }} title="{{ include.anchorTitle | replace: '%heading%', header }}"{% endcapture %}
+      {% endif %}
+
+      {% capture anchor %}<a {{ anchor }}>{{ include.anchorBody | replace: '%heading%', header | default: '' }}</a>{% endcapture %}
+
+      <!-- In order to prevent adding extra space after a heading, we'll let the 'anchor' value contain it -->
+      {% if beforeHeading %}
+        {% capture anchor %}{{ anchor }} {% endcapture %}
+      {% else %}
+        {% capture anchor %} {{ anchor }}{% endcapture %}
+      {% endif %}
+    {% endif %}
+
+    {% capture new_heading %}
+      <h{{ _hAttrToStrip }}
+        {{ include.bodyPrefix }}
+        {% if beforeHeading %}
+          {{ anchor }}{{ header }}
+        {% else %}
+          {{ header }}{{ anchor }}
+        {% endif %}
+        {{ include.bodySuffix }}
+      </h{{ _workspace | last }}
+    {% endcapture %}
+    {% capture edited_headings %}{{ edited_headings }}{{ new_heading }}{% endcapture %}
+  {% endfor %}
+{% endcapture %}{% assign headingsWorkspace = '' %}{{ edited_headings | strip }}

_includes/main.html

@@ -1,5 +1,5 @@
 <main id="mainContent">
   <a id="editButton" class="button" href="{{ site.github.repository_url }}/edit/{{ site.github.source.branch }}/{{ page.path }}">Edit Page</a>
   <h1>{{ page.title }}</h1>
-  {{ content }}
+  {% include anchor_headings.html html=content h_max=3 anchorTitle='Back to top' anchorBody='Back ↑' anchorClass='backToTop' linkOverride='#top' %}
 </main>

_layouts/default.html

@@ -6,6 +6,7 @@
   <body>
     {% include header.html %}
 
+    <a id="top"></a>
     <div class="page-body">
       <div class="wrapper">
           <div class="main-container">

assets/css/style.scss

@@ -293,6 +293,17 @@ main {
     border-bottom: none;
   }
 
+  a.backToTop {
+    font-size: 14px;
+    float: right;
+
+    // Hide as long as we have a sidebar
+    display: none;
+    @media (max-width: 1000px) {
+      display: inline;
+    }
+  }
+
   p, ul, ol {
     margin: 15px 0;
     line-height: 1.5;