remark

unified processor with support for parsing from markdown and serializing to markdown.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • remark()
• Examples
  • Example: checking markdown
  • Example: passing options to remark-stringify
• Syntax
• Syntax tree
• Types
• Compatibility
• Security
• Contribute
• Sponsor
• License

What is this?

This package is a unified processor with support for parsing markdown as input and serializing markdown as output by using unified with remark-parse and remark-stringify.

See the monorepo readme for info on what the remark ecosystem is.

When should I use this?

You can use this package when you want to use unified, have markdown as input, and want markdown as output. This package is a shortcut for unified().use(remarkParse).use(remarkStringify). When the input isn’t markdown (meaning you don’t need remark-parse) or the output is not markdown (you don’t need remark-stringify), it’s recommended to use unified directly.

When you want to inspect and format markdown files in a project on the command line, you can use remark-cli.

Install

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

npm install remark

In Deno with esm.sh:

import {remark} from 'https://esm.sh/remark@15'

In browsers with esm.sh:

<script type="module">
  import {remark} from 'https://esm.sh/remark@15?bundle'
</script>

Use

Say we have the following module example.js:

import {remark} from 'remark'
import remarkToc from 'remark-toc'

const doc = `
# Pluto

Pluto is a dwarf planet in the Kuiper belt.

## Contents

## History

### Discovery

In the 1840s, Urbain Le Verrier used Newtonian mechanics to predict the position of…

### Name and symbol

The name Pluto is for the Roman god of the underworld, from a Greek epithet for Hades…

### Planet X disproved

Once Pluto was found, its faintness and lack of a viewable disc cast doubt…

## Orbit

Pluto's orbital period is about 248 years…
`

const file = await remark()
  .use(remarkToc, {heading: 'contents', tight: true})
  .process(doc)

console.error(String(file))

…running that with node example.js yields:

# Pluto

Pluto is a dwarf planet in the Kuiper belt.

## Contents

* [History](#history)
  * [Discovery](#discovery)
  * [Name and symbol](#name-and-symbol)
  * [Planet X disproved](#planet-x-disproved)
* [Orbit](#orbit)

## History

### Discovery

In the 1840s, Urbain Le Verrier used Newtonian mechanics to predict the position of…

### Name and symbol

The name Pluto is for the Roman god of the underworld, from a Greek epithet for Hades…

### Planet X disproved

Once Pluto was found, its faintness and lack of a viewable disc cast doubt…

## Orbit

Pluto's orbital period is about 248 years…

API

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

remark()

Create a new unified processor that already uses remark-parse and remark-stringify.

You can add more plugins with use. See unified for more information.

Examples

Example: checking markdown

The following example checks that markdown code style is consistent and follows some best practices:

import {remark} from 'remark'
import remarkPresetLintConsistent from 'remark-preset-lint-consistent'
import remarkPresetLintRecommended from 'remark-preset-lint-recommended'
import {reporter} from 'vfile-reporter'

const file = await remark()
  .use(remarkPresetLintConsistent)
  .use(remarkPresetLintRecommended)
  .process('1) Hello, _Jupiter_ and *Neptune*!')

console.error(reporter(file))

Yields:

          warning Missing newline character at end of file final-newline             remark-lint
1:1-1:35  warning Marker style should be `.`               ordered-list-marker-style remark-lint
1:4       warning Incorrect list-item indent: add 1 space  list-item-indent          remark-lint
1:25-1:34 warning Emphasis should use `_` as a marker      emphasis-marker           remark-lint

⚠ 4 warnings

Example: passing options to remark-stringify

When you use remark-stringify manually you can pass options to use. Because remark-stringify is already used in remark, that’s not possible. To define options for remark-stringify, you can instead pass options to data:

import {remark} from 'remark'

const doc = `
# Moons of Neptune

1. Naiad
2. Thalassa
3. Despine
4. …
`

const file = await remark()
  .data('settings', {
    bulletOrdered: ')',
    incrementListMarker: false,
    setext: true
  })
  .process(doc)

console.log(String(file))

Yields:

Moons of Neptune
================

1) Naiad
1) Thalassa
1) Despine
1) …

Syntax

Markdown is parsed and serialized according to CommonMark. Other plugins can add support for syntax extensions.

Syntax tree

The syntax tree used in remark is mdast.

Types

This package is fully typed with TypeScript. There are no extra exported types.

It also registers Settings with unified. If you’re passing options with .data('settings', …), make sure to import this package somewhere in your types, as that registers the fields.

/// <reference types="remark" />

import {unified} from 'unified'

// @ts-expect-error: `thisDoesNotExist` is not a valid option.
unified().data('settings', {thisDoesNotExist: false})

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, remark@^15, compatible with Node.js 16.

Security

As markdown can be turned into HTML and improper use of HTML can open you up to cross-site scripting (XSS) attacks, use of remark can be unsafe. When going to HTML, you will combine remark with rehype, in which case you should use rehype-sanitize.

Use of remark plugins could also open you up to other attacks. Carefully assess each plugin and the risks involved in using them.

For info on how to submit a report, see our security policy.

Contribute

See contributing.md in remarkjs/.github for ways to get started. See support.md for ways to get help. Join us in Discussions to chat with the community and contributors.

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

Sponsor

Support this effort and give back by sponsoring on OpenCollective!

License

MIT © Titus Wormer