markdown-it-github-headings

Add GitHub style anchor tags to headers

Install

npm install --save @gerhobbelt/markdown-it-github-headings

Usage

1var md = require('@gerhobbelt/markdown-it')()
2  .use(require('@gerhobbelt/markdown-it-github-headings'), options)
3
4md.render('# hello')

Options and Defaults

The defaults will make the heading anchors behave as close to how GitHub behaves as possible.

Name	Description	Default
className	name of the class that will be added to the anchor tag	anchor
prefixHeadingIds	add a prefix to each heading ID. (see security note below)	true
prefix	if prefixHeadingIds is true, use this string to prefix each ID.	user-content-
enableHeadingLinkIcons	Adds the icon next to each heading	true
linkIcon	If enableHeadingLinkIcons is true, use this to supply a custom icon (or anything really)
resetSlugger	reset the slugger counter between .render calls for duplicate headers. (See tests for example)	true

Why should I prefix heading IDs?

When using user generated content, its possible to run into DOM Clobbering when heading IDs are generated. Since IDs are used by JavaScript and CSS, a user could craft a page that breaks functionality or styles. A good way to avoid clobbering is to add a prefix to every generated ID to ensure they cannot overlap with existing IDs.

If you have full control over the content, there is less of a risk, but be aware that strange bugs related to DOM Clobbering are still possible!

For more information, here are some good resources on the topic:

• User-generated content and DOM clobbering
• In the DOM, no one will hear you scream
• A discussion about GitHub implementation
• An open issue on markdown-it repo

But the prefixes make links look real gross.

One solution is to write some client side JavaScript to force non-prefixed hashes to jump to prefixed anchors. This is how its handled on GitHub and npmjs.com.

Check out marky-deep-links for an example (works great with browserify or webpack).

Contributing

Contributions welcome! Please read the contributing guidelines first.

License

ISC