mdast-util-to-markdown

mdast utility to parse markdown.

When to use this

Use this if you have direct access to an AST and need to serialize it. Use remark instead, which includes this, but has a nice interface and hundreds of plugins.

Install

This package is ESM only: Node 12+ is needed to use it and it must be imported instead of required.

npm:

npm install mdast-util-to-markdown

Use

Say we have the following script, example.js:

import {toMarkdown} from 'mdast-util-to-markdown'

var tree = {
  type: 'root',
  children: [
    {
      type: 'blockquote',
      children: [
        {type: 'thematicBreak'},
        {
          type: 'paragraph',
          children: [
            {type: 'text', value: '- a\nb !'},
            {
              type: 'link',
              url: 'example.com',
              children: [{type: 'text', value: 'd'}]
            }
          ]
        }
      ]
    }
  ]
}

console.log(toMarkdown(tree))

Now, running node example yields (note the properly escaped characters which would otherwise turn into a list and image respectively):

> ***
>
> \- a
> b \![d](example.com)

API

This package exports the following identifier: toMarkdown. There is no default export.

`toMarkdown(tree[, options])`

Serialize mdast to markdown.

Formatting options

`options.bullet`

Marker to use to for bullets of items in unordered lists ('*', '+', or '-', default: '*').

`options.closeAtx`

Whether to add the same number of number signs (#) at the end of an ATX heading as the opening sequence (boolean, default: false).

`options.emphasis`

Marker to use to serialize emphasis ('*' or '_', default: '*').

`options.fence`

Marker to use to serialize fenced code ('`' or '~', default: '`').

`options.fences`

Whether to use fenced code always (boolean, default: false). The default is to fenced code if there is a language defined, if the code is empty, or if it starts or ends in empty lines.

`options.incrementListMarker`

Whether to increment the value of bullets of items in ordered lists (boolean, default: true).

`options.listItemIndent`

Whether to indent the content of list items with the size of the bullet plus one space (when 'one') or a tab stop ('tab'), or depending on the item and its parent list ('mixed', uses 'one' if the item and list are tight and 'tab' otherwise) ('one', 'tab', or 'mixed', default: 'tab').

`options.quote`

Marker to use to serialize titles ('"' or "'", default: '"').

`options.resourceLink`

Whether to use resource links ([text](url)) always (boolean, default: false). The default is to use autolinks (<https://example.com>) when possible.

`options.rule`

Marker to use for thematic breaks ('*', '-', or '_', default: '*').

`options.ruleRepetition`

Number of markers to use for thematic breaks (number, default: 3, min: 3).

`options.ruleSpaces`

Whether to add spaces between markers in thematic breaks (boolean, default: false).

`options.setext`

Whether to use setext headings when possible (boolean, default: false). Setext headings are not possible for headings with a rank more than 2 or when they’re empty.

`options.strong`

Marker to use to serialize strong ('*' or '_', default: '*').

`options.tightDefinitions`

Whether to join definitions w/o a blank line (boolean, default: false). Shortcut for a join function like so:

function (left, right) {
  if (left.type === 'definition' && right.type === 'definition') {
    return 0
  }
}

`options.handlers`

Object mapping node types to custom handlers. Useful for syntax extensions. Take a look at lib/handle for examples.

`options.join`

List of functions used to determine what to place between two flow nodes. Often, they are joined by one blank line. In certain cases, it’s nicer to have them next to each other. Or, they can’t occur together. These functions receive two adjacent nodes and their parent and can return number or boolean, referring to how many blank lines to use between them. A return value of true is as passing 1. A return value of false means the nodes cannot be joined by a blank line, such as two adjacent block quotes or indented code after a list, in which case a comment will be injected to break them up:

> Quote 1

<!---->

> Quote 2

`options.unsafe`

List of patterns to escape. Useful for syntax extensions. Take a look at lib/unsafe.js for examples.

Extension options

`options.extensions`

List of extensions (Array.<ToMarkdownExtension>). Each ToMarkdownExtension is an object with the same interface as options here.

Returns

string — Serialized markdown.

List of extensions

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

Security

mdast-util-to-markdown will do its best to serialize markdown to match the syntax tree, but there are several cases where that is impossible. It’ll do its best, but complete roundtripping is impossible given that any value could be injected into the tree.

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-to-markdown and parsing it again later could potentially be unsafe. When parsing markdown afterwards and then going to HTML, use something like hast-util-sanitize to make the tree safe.

micromark/micromark — the smallest commonmark-compliant markdown parser that exists
remarkjs/remark — markdown processor powered by plugins
syntax-tree/mdast-util-from-markdown — parse markdown to mdast

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.