mdast-util-toc

mdast utility to generate a table of contents.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • toc(tree[, options])
  • Options
  • Result
• HTML
• Types
• Compatibility
• Security
• Related
• Contribute
• License

What is this?

This package is a utility that generates a table of contents from a document.

When should I use this?

This utility is useful to generate a section so users can more easily navigate through a document.

This package is wrapped in remark-toc for ease of use with remark, where it also injects the table of contents into the document.

Install

This package is ESM only. In Node.js (version 16+), install with npm:

npm install mdast-util-toc

In browsers with esm.sh:

<script type="module">
  import {toc} from 'https://esm.sh/mdast-util-toc@7?bundle'
</script>

Use

/**
 * @import {Root} from 'mdast'
 */

import {toc} from 'mdast-util-toc'

/** @type {Root} */
const tree = {
  type: 'root',
  children: [
    {type: 'heading', depth: 1, children: [{type: 'text', value: 'Alpha'}]},
    {type: 'heading', depth: 2, children: [{type: 'text', value: 'Bravo'}]},
    {type: 'heading', depth: 3, children: [{type: 'text', value: 'Charlie'}]},
    {type: 'heading', depth: 2, children: [{type: 'text', value: 'Delta'}]}
  ]
}

const table = toc(tree)

console.dir(table, {depth: 3})

Yields:

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

API

This package exports the identifier toc. There is no default export.

toc(tree[, options])

Generate a table of contents from tree.

Looks for the first heading matching options.heading (case insensitive) and returns a table of contents (a 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 in the list 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 options.parents.

Parameters

• tree (Node) — tree to search and generate from
• options (Options, optional) — configuration

Returns

Results (Result).

Options

Configuration (TypeScript type).

Fields

• heading (string, optional) — heading to look for, wrapped in new RegExp('^(' + value + ')$', 'i')
• maxDepth (number, default: 6) — maximum heading depth to include in the table of contents. This is inclusive: when set to 3, level three headings are included (those with three hashes, ###)
• minDepth (number, default: 1) — minimum heading depth to include in the table of contents. This is inclusive: when set to 3, level three headings are included (those with three hashes, ###)
• skip (string, optional) — headings to skip, wrapped in new RegExp('^(' + value + ')$', 'i'). Any heading matching this expression will not be present in the table of contents
• parents (Test, default: tree) — allow headings to be children of certain node types. Can be any unist-util-is compatible test
• tagfilter (boolean, default: false) — whether to handle HTML tags according to GFM tagfilter
• tight (boolean, default: false) — whether to compile list items tightly
• ordered (boolean, default: false) — whether to compile list items as an ordered list, otherwise they are unordered
• prefix (string, optional) — add a prefix to links to headings in the table of contents. Useful for example when later going from mdast to hast and sanitizing with hast-util-sanitize.

Result

Results (TypeScript type).

Fields

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

HTML

This utility does not add IDs to headings. Links in the table of contents point to the IDs that GitHub or rehype-slug would use.

HTML in headings is turned into slugs like GitHub, especially if tagfilter is on. GFM footnotes are correctly numbered if mdast-util-gfm-footnote is used. The exception is HTML that changes the document structure, such as a </h2> in a heading as that would require a complete HTML parser.

Types

This package is fully typed with TypeScript. It exports the types Options and Result.

Compatibility

Projects maintained by the unified collective are compatible with maintained versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line, mdast-util-toc@^7, compatible with Node.js 16.

Security

Use of mdast-util-toc does not change the tree and does not involve hast, so on its own it does not open you up to cross-site scripting (XSS) attacks.

But the content of headings is copied into the table of contents, so dangerous content in headings (such as embedded HTML) also ends up in map. 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 map, serialized:

* [Alpha](#alpha)

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

Always use hast-util-sanitize 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