mdast-util-toc

mdast utility to generate a table of contents.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • toc(node[, options])
• 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 12.20+, 14.14+, or 16.0+), install with npm:

npm install mdast-util-toc

In Deno with esm.sh:

import {toc} from 'https://esm.sh/mdast-util-toc@6'

In browsers with esm.sh:

<script type="module">
  import {toc} from 'https://esm.sh/mdast-util-toc@6?bundle'
</script>

Use

Dependencies:

/**
 * @typedef {import('mdast').Root} Root
 */

import {u} from 'unist-builder'
import {toc} from 'mdast-util-toc'

Now running:

const tree = /** @type {Root} */ (
  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')])
  ])
)

const table = toc(tree)

Yields:

{
  index: null,
  endIndex: null,
  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(node[, options])

Generate a table of contents from node.

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.

options

Configuration (optional).

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.ordered

Whether to compile list items as an ordered list (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

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

For example, the following code would allow headings under either root or blockquote to be used:

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

Returns

An object representing the table of contents:

• 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 table of contents
• 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

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 all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.

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