Add GitHub style anchor tags to headers
npm install markdown-it-github-headings
var md = require('markdown-it')()
.use(require('markdown-it-github-headings'), options)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 |
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
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).
Contributions welcome! Please read the contributing guidelines first.