eleventy-plugin-toc-a11y

• Step 1: Installation
• Step 2: Configuration
• Step 3: Usage
  • Default Options
  • Override Default Options
• References

This Eleventy (11ty) plugin generates a table of contents (TOC) from page headings using an Eleventy filter.

It adds a navigation landmark with a heading and ARIA role to make it accessible^{[1] [2]}. And creates a nested list of headings by level.

Markdown

# Fruits

## Apples

### Empire

### Fuji

### Pink Lady

## Pears

### Bartlett

### Bosc

### Starkrimson

HTML

<nav class="nav-toc" role="navigation" aria-labelledby="nav-toc">
  <h2 class="nav-toc-heading" id="nav-toc">Table of contents</h2>
  <ol class="nav-toc-list">
    <li class="nav-toc-list-item">
      <a class="nav-toc-list-item-anchor" href="#apples">Apples</a>
      <ol class="nav-toc-list">
        <li class="nav-toc-list-item"><a class="nav-toc-list-item-anchor" href="#empire">Empire</a></li>
        <li class="nav-toc-list-item"><a class="nav-toc-list-item-anchor" href="#fuji">Fuji</a></li>
        <li class="nav-toc-list-item"><a class="nav-toc-list-item-anchor" href="#pink-lady">Pink Lady</a></li>
      </ol>
    </li>
    <li class="nav-toc-list-item">
      <a class="nav-toc-list-item-anchor" href="#oranges">Pears</a>
      <ol class="nav-toc-list">
        <li class="nav-toc-list-item"><a class="nav-toc-list-item-anchor" href="#bartlett">Bartlett</a></li>
        <li class="nav-toc-list-item"><a class="nav-toc-list-item-anchor" href="#bosc">Bosc</a></li>
        <li class="nav-toc-list-item"><a class="nav-toc-list-item-anchor" href="#starkrimson">Starkrimson</a></li>
      </ol>
    </li>
  </ol>
</nav>

Step 1: Installation

npm install @thedigitalman/eleventy-plugin-toc-a11y --save-dev

Step 2: Configuration

All headings must have an id attribute. The plugin uses the id attribute of the headings it finds to build the navigation.

You can do this manually, but using markdown-it and markdown-it-anchor make it easy.

Open your Eleventy config file (probably .eleventy.js), use addPlugin, and add some Markdown settings.

const eleventyPluginTOC = require( '@thedigitalman/eleventy-plugin-toc-a11y' );
const markdownIt = require( 'markdown-it' );
const markdownItAnchor = require( 'markdown-it-anchor' );

module.exports = function ( eleventyConfig ) {
  // Plugins
  eleventyConfig.addPlugin( eleventyPluginTOC );

  // Markdown settings
  eleventyConfig.setLibrary( 'md',
    markdownIt().use( markdownItAnchor )
  );
}

Step 3: Usage

All headings must be in proper order without skipping levels ^[3].

Open a layout template file and add the filter before your content. This gives you a good outline, and lets people review the TOC before reading the content.

Liquid

{{ content | toc }}

<main>
  {{ content }}
</main>

Nunjucks

Always include the safe filter when using Nunjucks.

{{ content | toc | safe }}

<main>
  {{ content | safe }}
</main>

Default Options

{
  tags: ['h2', 'h3', 'h4', 'h5', 'h6'],
  wrapper: 'nav',
  wrapperClass: 'nav-toc',
  heading: true,
  headingClass: 'nav-toc-heading',
  headingLevel: 'h2',
  headingText: 'Table of contents',
  listType: 'ol',
  listClass: 'nav-toc-list',
  listItemClass: 'nav-toc-list-item',
  listItemAnchorClass: 'nav-toc-list-item-anchor'
}

Option	Data Type	Description	Notes
tags	Object	An array of heading levels to include in the TOC.	Page titles (i.e. h1) should be excluded.
wrapper	String	The navigation landmark element of the TOC.	In most cases use nav. If you replace it, be sure it’s valid HTML and accessible.
wrapperClass	String	The CSS class name for the TOC parent element.	Using an empty string removes the class attribute.
heading	Boolean	Whether the TOC uses a heading element.	Using heading text for sections helps everyone.
headingClass	String	The CSS class name for the TOC heading element.	Using an empty string removes the class attribute.
headingLevel	String	The level of the TOC heading element.	In most cases use h2, but you can use h2 – h6. If you replace it, be sure it’s valid HTML and accessible.
headingText	String	The TOC heading element text.	Keep it concise and relevant.
listType	String	The type of list for navigation items.	Use ol or ul. Other elements won’t work.
listClass	String	The CSS class name for the list.	Using an empty string removes the class attribute.
listItemClass	String	The CSS class name for each list item.	Using an empty string removes the class attribute.
listItemAnchorClass	String	The CSS class name for each anchor in a list item.	Using an empty string removes the class attribute.

Override Default Options

You can override the default options in the Eleventy config file or inline.

Eleventy config file

eleventyConfig.addPlugin( pluginToC, {
  wrapperClass: 'toc',
  headingClass: 'toc-heading',
  headingText: 'Topics',
  listType: 'ul'
});

Inline (Liquid)

{{ content | toc(wrapperClass='toc',headingClass='toc-heading',headingText='Topics',listType='ul') }}

Inline (Nunjucks)

{{ content | toc(wrapperClass='toc',headingClass='toc-heading',headingText='Topics',listType='ul') | safe }}

References

1. 4.3.6 Navigation | WAI-ARIA Authoring Practices 1.2 W3C ↑
2. Navigation Landmark: ARIA Landmark Example W3C ARIA Authoring Practices Task Force ↑
3. H42: Using h1-h6 to identify headings Techniques for WCAG 2.1 ↑