Header anchors for markdown-it.

const md = require('markdown-it')()
  .use(require('markdown-it-anchor'), opts)

See a demo as JSFiddle.

The opts object can contain:

The renderPermalink function takes the slug, an options object with the above options, and then all the usual markdown-it rendering arguments.

All headers above level will then have an id attribute with a slug of their content. level can also be an array of headers levels to apply the anchor, like [2, 3] to have an anchor on only level 2 and 3 headers.

If permalink is true, a ¶ symbol linking to the header itself will be added.

You may want to use the link symbol as permalinkSymbol, or a symbol from your favorite web font.

The callback option is a function that will be called at the end of rendering with the token and an info object. The info object has title and slug properties with the token content and the slug used for the identifier.

Starting from v5.0.0, markdown-it-anchor dropped package string keeping it's core value of being an unopinionated and secure library. Yet, users looking for backward compatibility may want the old slugify:

$ npm i -S string

const string = require('string')
const legacySlugify = s => string(s).slugify().toString()

const md = require('markdown-it')()
const anchor = require('markdown-it-anchor', {
	slugify: legacySlugify
})

Unicode is supported by default. Yet, if you are looking for a "prettier" --opinionated-- link, i.e without %xx, you may want to take a look at uslug:

$ npm i -S uslug

const uslug = require('uslug')
const uslugify = s => uslug(s)

const md = require('markdown-it')()
const anchor = require('markdown-it-anchor', {
	slugify: uslugify
})

Looking for an automatic table of contents (TOC) generator? Take a look at markdown-it-toc-done-right it's made from the ground to be a great companion of this plugin.