mdast-util-from-markdown

mdast utility that turns markdown into a syntax tree.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • fromMarkdown(value[, encoding][, options])
  • CompileContext
  • CompileData
  • Encoding
  • Extension
  • Handle
  • OnEnterError
  • OnExitError
  • Options
  • Token
  • Transform
  • Value
• List of extensions
• Syntax
• Syntax tree
• Types
• Compatibility
• Security
• Related
• Contribute
• License

What is this?

This package is a utility that takes markdown input and turns it into an mdast syntax tree.

This utility uses micromark, which turns markdown into tokens, and then turns those tokens into nodes. This package is used inside remark-parse, which focusses on making it easier to transform content by abstracting these internals away.

When should I use this?

If you want to handle syntax trees manually, use this. When you just want to turn markdown into HTML, use micromark instead. For an easier time processing content, use the remark ecosystem instead.

You can combine this package with other packages to add syntax extensions to markdown. Notable examples that deeply integrate with this package are mdast-util-gfm, mdast-util-mdx, mdast-util-frontmatter, mdast-util-math, and mdast-util-directive.

Install

This package is ESM only. In Node.js (version 14.14+ and 16.0+), install with npm:

npm install mdast-util-from-markdown

In Deno with esm.sh:

import {fromMarkdown} from 'https://esm.sh/mdast-util-from-markdown@1'

In browsers with esm.sh:

<script type="module">
  import {fromMarkdown} from 'https://esm.sh/mdast-util-from-markdown@1?bundle'
</script>

Use

Say we have the following markdown file example.md:

## Hello, *World*!

…and our module example.js looks as follows:

import fs from 'node:fs/promises'
import {fromMarkdown} from 'mdast-util-from-markdown'

const doc = await fs.readFile('example.md')
const tree = fromMarkdown(doc)

console.log(tree)

…now running node example.js yields (positional info removed for brevity):

{
  type: 'root',
  children: [
    {
      type: 'heading',
      depth: 2,
      children: [
        {type: 'text', value: 'Hello, '},
        {type: 'emphasis', children: [{type: 'text', value: 'World'}]},
        {type: 'text', value: '!'}
      ]
    }
  ]
}

API

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

The export map supports the development condition. Run node --conditions development example.js to get instrumented dev code. Without this condition, production code is loaded.

fromMarkdown(value[, encoding][, options])

Turn markdown into a syntax tree.

Overloads

• (value: Value, encoding: Encoding, options?: Options) => Root
• (value: Value, options?: Options) => Root

Parameters

• value (Value) — markdown to parse
• encoding (Encoding, default: 'utf8') — character encoding for when value is Buffer
• options (Options, optional) — configuration

Returns

mdast tree (Root).

CompileContext

mdast compiler context (TypeScript type).

Fields

• stack (Array<Node>) — stack of nodes
• tokenStack (Array<[Token, OnEnterError | undefined]>) — stack of tokens
• getData ((key: string) => unknown) — get data from the key/value store (see CompileData)
• setData ((key: string, value?: unknown) => void) — set data into the key/value store (see CompileData)
• buffer (() => void) — capture some of the output data
• resume (() => string) — stop capturing and access the output data
• enter ((node: Node, token: Token, onError?: OnEnterError) => Node) — enter a token
• exit ((token: Token, onError?: OnExitError) => Node) — exit a token
• sliceSerialize ((token: Token, expandTabs?: boolean) => string) — get the string value of a token
• config (Required<Extension>) — configuration

CompileData

Interface of tracked data (TypeScript type).

Type

interface CompileData { /* see code */ }

When working on extensions that use more data, extend the corresponding interface to register their types:

declare module 'mdast-util-from-markdown' {
  interface CompileData {
    // Register a new field.
    mathFlowInside?: boolean | undefined
  }
}

Encoding

Encodings supported by the Buffer class (TypeScript type).

See micromark for more info.

Type

type Encoding = 'utf8' | /* … */

Extension

Change how markdown tokens from micromark are turned into mdast (TypeScript type).

Properties

• canContainEols (Array<string>, optional) — token types where line endings are used
• enter (Record<string, Handle>, optional) — opening handles
• exit (Record<string, Handle>, optional) — closing handles
• transforms (Array<Transform>, optional) — tree transforms

Handle

Handle a token (TypeScript type).

Parameters

• this (CompileContext) — context
• token (Token) — current token

Returns

Nothing (void).

OnEnterError

Handle the case where the right token is open, but it is closed (by the left token) or because we reached the end of the document (TypeScript type).

Parameters

• this (CompileContext) — context
• left (Token or undefined) — left token
• right (Token) — right token

Returns

Nothing (void).

OnExitError

Handle the case where the right token is open but it is closed by exiting the left token (TypeScript type).

Parameters

• this (CompileContext) — context
• left (Token) — left token
• right (Token) — right token

Returns

Nothing (void).

Options

Configuration (TypeScript type).

Properties

• extensions (Array<MicromarkExtension>, optional) — micromark extensions to change how markdown is parsed
• mdastExtensions (Array<Extension | Array<Extension>>, optional) — extensions for this utility to change how tokens are turned into a tree

Token

Token from micromark (TypeScript type).

See micromark for more info.

Type

type Token = { /* … */ }

Transform

Extra transform, to change the AST afterwards (TypeScript type).

Parameters

• tree (Root) — tree to transform

Returns

New tree (Root) or nothing (in which case the current tree is used).

Value

Contents of the file (TypeScript type).

See micromark for more info.

Type

type Value = string | Uint8Array

List of extensions

• syntax-tree/mdast-util-directive — directives
• syntax-tree/mdast-util-frontmatter — frontmatter (YAML, TOML, more)
• syntax-tree/mdast-util-gfm — GFM
• syntax-tree/mdast-util-gfm-autolink-literal — GFM autolink literals
• syntax-tree/mdast-util-gfm-footnote — GFM footnotes
• syntax-tree/mdast-util-gfm-strikethrough — GFM strikethrough
• syntax-tree/mdast-util-gfm-table — GFM tables
• syntax-tree/mdast-util-gfm-task-list-item — GFM task list items
• syntax-tree/mdast-util-math — math
• syntax-tree/mdast-util-mdx — MDX
• syntax-tree/mdast-util-mdx-expression — MDX expressions
• syntax-tree/mdast-util-mdx-jsx — MDX JSX
• syntax-tree/mdast-util-mdxjs-esm — MDX ESM

Syntax

Markdown is parsed according to CommonMark. Extensions can add support for other syntax. If you’re interested in extending markdown, more information is available in micromark’s readme.

Syntax tree

The syntax tree is mdast.

Types

This package is fully typed with TypeScript. It exports the additional types CompileContext, CompileData, Encoding, Extension, Handle, OnEnterError, OnExitError, Options, Token, Transform, and Value.

Compatibility

Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 14.14+ and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.

Security

As markdown is sometimes used for HTML, and improper use of HTML can open you up to a cross-site scripting (XSS) attack, use of mdast-util-from-markdown can also be unsafe. When going to HTML, use this utility in combination with hast-util-sanitize to make the tree safe.

Related

• syntax-tree/mdast-util-to-markdown — serialize mdast as markdown
• micromark/micromark — parse markdown
• remarkjs/remark — process markdown

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 © Titus Wormer

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