mdast-util-toc

What is mdast-util-toc?

The `mdast-util-toc` package is a utility for generating a Table of Contents (TOC) from Markdown Abstract Syntax Trees (MDAST). It is particularly useful for processing Markdown documents and extracting a structured TOC based on headings.

What are mdast-util-toc's main functionalities?

Generate TOC from MDAST

This feature allows you to generate a Table of Contents from a Markdown Abstract Syntax Tree. The code sample demonstrates how to convert a Markdown string into an MDAST, generate a TOC from it, and then convert the TOC back into a Markdown string.

const { toMarkdown } = require('mdast-util-to-markdown');
const { fromMarkdown } = require('mdast-util-from-markdown');
const { toc } = require('mdast-util-toc');

const markdown = '# Title\n## Subtitle\n### Sub-subtitle';
const tree = fromMarkdown(markdown);
const tocNode = toc(tree);
console.log(toMarkdown(tocNode.map));

Custom Heading Levels

This feature allows you to customize the depth of headings included in the TOC. The code sample demonstrates generating a TOC that includes only headings up to level 2.

const { fromMarkdown } = require('mdast-util-from-markdown');
const { toc } = require('mdast-util-toc');

const markdown = '# Title\n## Subtitle\n### Sub-subtitle';
const tree = fromMarkdown(markdown);
const tocNode = toc(tree, { maxDepth: 2 });
console.log(tocNode.map);

Custom TOC Heading

This feature allows you to specify a custom heading for the TOC. The code sample demonstrates generating a TOC with a custom heading 'Table of Contents'.

const { fromMarkdown } = require('mdast-util-from-markdown');
const { toc } = require('mdast-util-toc');

const markdown = '# Title\n## Subtitle\n### Sub-subtitle';
const tree = fromMarkdown(markdown);
const tocNode = toc(tree, { heading: 'Table of Contents' });
console.log(tocNode.map);

Other packages similar to mdast-util-toc

remark-toc

The `remark-toc` package is a plugin for the `remark` Markdown processor that generates a Table of Contents. It is similar to `mdast-util-toc` but is designed to be used directly within the `remark` ecosystem, making it easier to integrate if you are already using `remark`.

markdown-toc

The `markdown-toc` package generates a Table of Contents for Markdown files. Unlike `mdast-util-toc`, which works with MDAST, `markdown-toc` operates directly on Markdown strings, making it simpler to use for straightforward TOC generation without needing to parse the Markdown into an abstract syntax tree.

markdown-it-toc-done-right

The `markdown-it-toc-done-right` package is a plugin for the `markdown-it` Markdown parser that generates a Table of Contents. It is similar to `mdast-util-toc` in functionality but is designed to work within the `markdown-it` ecosystem, providing seamless integration if you are using `markdown-it` for Markdown processing.

README

mdast-util-toc

mdast utility to generate table of contents.

Install

npm:

npm install mdast-util-toc

Use

Dependencies:

var u = require('unist-builder')
var toc = require('mdast-util-toc')

Given a mdast tree:

var tree = u('root', [
  u('heading', {depth: 1}, [u('text', 'Alpha')]),
  u('heading', {depth: 2}, [u('text', 'Bravo')]),
  u('heading', {depth: 3}, [u('text', 'Charlie')]),
  u('heading', {depth: 2}, [u('text', 'Delta')])
])

var table = toc(tree)

Yields:

{
  index: null,
  endIndex: null,
  map: {
    type: 'list',
    ordered: false,
    spread: true,
    children: [ { type: 'listItem', spread: true, children: [Array] } ]
  }
}

API

toc(tree[, options])

Generate a Table of Contents from a tree.

Looks for the first heading matching options.heading (case insensitive, supports alt/title attributes for links and images too), and returns a table of contents (list) for all following headings. If no heading is specified, creates a table of contents for all headings in tree. tree is not changed.

Links to headings are based on GitHub’s style. Only top-level headings (those not in blockquotes or lists), are used. This default behavior can be changed by passing parents.

options

options.heading

Heading to look for (string), wrapped in new RegExp('^(' + value + ')$', 'i').

options.maxDepth

Maximum heading depth to include in the table of contents (number, default: 6), This is inclusive: when set to 3, level three headings are included (those with three hashes, ###).

options.skip

Headings to skip (string, optional), wrapped in new RegExp('^(' + value + ')$', 'i'). Any heading matching this expression will not be present in the table of contents.

options.tight

Whether to compile list-items tightly (boolean?, default: false).

options.prefix

Add a prefix to links to headings in the table of contents (string?, default: null). Useful for example when later going from mdast to hast and sanitizing with hast-util-sanitize.

options.parents

Allows headings to be children of certain node types (default: the to toc given tree, to only allow top-level headings). Internally, uses unist-util-is to check, so parents can be any is-compatible test.

For example, this would allow headings under either root or blockquote to be used:

toc(tree, {parents: ['root', 'blockquote']})

Returns

An object representing the table of contents.

Properties

• index (number?) — Index of the node right after the table of contents heading. -1 if no heading was found, null if no heading was given
• endIndex (number?) — Index of the first node after heading that is not part of its section. -1 if no heading was found, null if no heading was given, same as index if there are no nodes between heading and the first heading in the TOC
• map (Node?) — List representing the generated table of contents. null if no table of contents could be created, either because no heading was found or because no following headings were found

Security

Use of mdast-util-toc does not involve hast, user content, or change the tree, so there are no openings for cross-site scripting (XSS) attacks.

Injecting map into the syntax tree may open you up to XSS attacks as existing nodes are copied into the table of contents. The following example shows how an existing script is copied into the table of contents.

For the following Markdown:

# Alpha

## Bravo<script>alert(1)</script>

## Charlie

Yields in map:

-   [Alpha](#alpha)

    -   [Bravo<script>alert(1)</script>](#bravoscriptalert1script)
    -   [Charlie](#charlie)

Always use hast-util-santize when transforming to hast.

Related

• github-slugger — Generate a slug just like GitHub does
• unist-util-visit — visit nodes
• unist-util-visit-parents — like visit, but with a stack of parents

Contribute

See contributing.md in syntax-tree/.github for ways to get started. See support.md for ways to get help.

This project has a code of conduct. By interacting with this repository, organization, or community you agree to abide by its terms.

License

MIT © Jonathan Haines