Jekyll Pure Liquid Table of Contents

GitHub Pages can't run custom Jekyll plug-ins so when generating Tables of Contents (TOCs), you're stuck with either a JavaScript solution or using kramdown's {:toc} option. However, by using {:toc}, you are forced to have that code next to your actual markdown and you can't place it in a layout. This means every. single. post. will need to have the snippet. If you choose the JavaScript approach, that's perfectly fine but what if JS is disabled on the someone's browser or your page is just really long and it becomes inefficient.

Instead, I wrote this solution entirely in Liquid and can be used as an {% include %} in any website you want, in any layout you want. Want to see it in action? Here are some awesome websites that I know of using this solution ❤️.

• the docs.docker.com website
• the UK Ministry of Justice Technical Guidance site
• "Minimal Mistakes" Jekyll Theme
• Apache's Beam and PDFBox websites
• JetBrains' OSS Jekyll Theme
• Bitcoin.org
• CloudCannon
• British Antarctic Survey
• Travis CI Docs
• the City of Amsterdam
• Intuit's Karate
• Duality's developer docs

For more information regarding how this include works, read the blog post.

Want anchors next to your Jekyll headings without JavaScript or a plug-in?

Check out the sister project over at allejo/jekyll-anchor-headings.

Usage

Alright, so how do you use it?

1. Download the latest toc.html file

2. Toss that file in your _includes folder.

3. Use it in your template layout where you have {{ content }} which is the HTML rendered from the markdown source with this liquid tag:

   {% include toc.html html=content %}

Parameters

This snippet is highly customizable. Here are the available parameters to change the behavior of the snippet.

Parameter	Type	Default	Description
html	string	*	the HTML of compiled markdown generated by kramdown in Jekyll
sanitize	bool	false	when set to true, the headers will be stripped of any HTML in the TOC
class	string	''	a CSS class assigned to the TOC; concat multiple classes with '.'
id	string	''	an ID to be assigned to the TOC
h_min	int	1	the minimum TOC header level to use; any heading lower than this value will be ignored
h_max	int	6	the maximum TOC header level to use; any heading greater than this value will be ignored
ordered	bool	false	when set to true, an ordered list will be outputted instead of an unordered list
item_class	string	''	add custom class for each list item; has support for %level% placeholder, which is the current heading level
baseurl	string	''	add a base url to the TOC links for when your TOC is on another page than the actual content
anchor_class	string	''	add custom class(es) for each anchor element

^* This is a required parameter

Performance

The performance impact of this snippet on your site is pretty negligible. The stats below were gotten from Jekyll's --profile option.

Filename                              | Count |      Bytes |    Time
--------------------------------------+-------+------------+--------

# performance on docs.docker.com from ~Feb 2017
_includes/toc.html                    |   813 |    524.17K |  6.422

# performance on the "Minimal Mistakes" Jekyll theme
_includes/toc.html                    |    94 |     29.43K |  0.413

License

This snippet may be redistributed under either the BSD-3 or MIT licenses.