markdown-it-anchor

What is markdown-it-anchor?

The markdown-it-anchor package is a plugin for the markdown-it Markdown parser that automatically adds anchor links to headings in your Markdown content. This is particularly useful for generating table of contents, permalinks, and improving navigation within long documents.

What are markdown-it-anchor's main functionalities?

Adding Anchor Links to Headings

This feature automatically adds anchor links to all headings in the Markdown content. The code sample demonstrates how to use the markdown-it-anchor plugin with markdown-it to process a simple Markdown string containing headings.

const markdownIt = require('markdown-it');
const markdownItAnchor = require('markdown-it-anchor');

const md = markdownIt().use(markdownItAnchor);

const result = md.render('# Heading 1\n## Heading 2');
console.log(result);

Customizing Anchor Link Properties

This feature allows customization of the anchor links, such as adding a permalink symbol, setting a custom CSS class, and more. The code sample shows how to configure these options when initializing the plugin.

const markdownIt = require('markdown-it');
const markdownItAnchor = require('markdown-it-anchor');

const md = markdownIt().use(markdownItAnchor, {
  permalink: true,
  permalinkClass: 'custom-class',
  permalinkSymbol: '🔗'
});

const result = md.render('# Heading 1\n## Heading 2');
console.log(result);

Slugification of Headings

This feature allows customization of the slugification process for generating anchor links. The code sample demonstrates how to provide a custom slugification function to the plugin.

const markdownIt = require('markdown-it');
const markdownItAnchor = require('markdown-it-anchor');

const md = markdownIt().use(markdownItAnchor, {
  slugify: s => s.toLowerCase().replace(/[^a-z0-9]+/g, '-')
});

const result = md.render('# Custom Heading!\n## Another Heading');
console.log(result);

Other packages similar to markdown-it-anchor

markdown-it-toc-done-right

The markdown-it-toc-done-right package is another plugin for markdown-it that focuses on generating a table of contents (TOC) for Markdown documents. It provides more advanced TOC generation features compared to markdown-it-anchor, such as automatic TOC insertion and customizable TOC levels.

markdown-it-toc-and-anchor

The markdown-it-toc-and-anchor package combines the functionalities of both table of contents generation and anchor link creation. It offers a more integrated solution for users who need both features in one package, whereas markdown-it-anchor focuses solely on anchor links.

markdown-it-headinganchor

The markdown-it-headinganchor package is a simpler alternative to markdown-it-anchor, providing basic functionality for adding anchor links to headings. It is less customizable but may be sufficient for users with straightforward requirements.

README

markdown-it-anchor

Header anchors for markdown-it.

English | 中文 (v7.0.1)

Usage

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

See a demo as JSFiddle.

The opts object can contain:

Name	Description	Default
level	Minimum level to apply anchors on or array of selected levels.	1
slugify	A custom slugification function.	See index.js
uniqueSlugStartIndex	Index to start with when making duplicate slugs unique.	1
permalink	Whether to add permalinks next to titles.	false
renderPermalink	A custom permalink rendering function.	See index.js
permalinkClass	The class of the permalink anchor.	header-anchor
permalinkSpace	Place space between the header text and the permalink anchor.	true
permalinkSymbol	The symbol in the permalink anchor.	¶
permalinkBefore	Place the permalink before the title.	false
permalinkHref	A custom permalink href rendering function.	See index.js
permalinkAttrs	A custom permalink attributes rendering function.	See index.js
callback	Called with token and info after rendering.	undefined

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.

User-Friendly URLs

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 Support

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
})

Table of Contents

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.

Browser Example

See example.html.