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mdast-util-directive

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mdast extensions to parse and serialize generic directives proposal (:cite[smith04], ::youtube[Video of a cat in a box]{v=01ab2cd3efg}, and such).

Contents

What is this?

This package contains two extensions that add support for directive syntax in markdown to mdast. These extensions plug into mdast-util-from-markdown (to support parsing directives in markdown into a syntax tree) and mdast-util-to-markdown (to support serializing directives in syntax trees to markdown).

When to use this

Directives are one of the four ways to extend markdown: an arbitrary extension syntax (see Extending markdown in micromark’s docs for the alternatives and more info). This mechanism works well when you control the content: who authors it, what tools handle it, and where it’s displayed. When authors can read a guide on how to embed a tweet but are not expected to know the ins and outs of HTML or JavaScript. Directives don’t work well if you don’t know who authors content, what tools handle it, and where it ends up. Example use cases are a docs website for a project or product, or blogging tools and static site generators.

You can use these extensions when you are working with mdast-util-from-markdown and mdast-util-to-markdown already.

When working with mdast-util-from-markdown, you must combine this package with micromark-extension-directive.

When you don’t need a syntax tree, you can use micromark directly with micromark-extension-directive.

All these packages are used remark-directive, which focusses on making it easier to transform content by abstracting these internals away.

This package only handles the syntax tree. For example, it does not handle how markdown is turned to HTML. You can use this with some more code to match your specific needs, to allow for anything from callouts, citations, styled blocks, forms, embeds, spoilers, etc. Traverse the tree to change directives to whatever you please.

Install

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

npm install mdast-util-directive

In Deno with esm.sh:

import {directiveFromMarkdown, directiveToMarkdown} from 'https://esm.sh/mdast-util-directive@3'

In browsers with esm.sh:

<script type="module">
  import {directiveFromMarkdown, directiveToMarkdown} from 'https://esm.sh/mdast-util-directive@3?bundle'
</script>

Use

Say our document example.md contains:

A lovely language know as :abbr[HTML]{title="HyperText Markup Language"}.

…and our module example.js looks as follows:

import fs from 'node:fs/promises'
import {fromMarkdown} from 'mdast-util-from-markdown'
import {toMarkdown} from 'mdast-util-to-markdown'
import {directive} from 'micromark-extension-directive'
import {directiveFromMarkdown, directiveToMarkdown} from 'mdast-util-directive'

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

const tree = fromMarkdown(doc, {
  extensions: [directive()],
  mdastExtensions: [directiveFromMarkdown()]
})

console.log(tree)

const out = toMarkdown(tree, {extensions: [directiveToMarkdown()]})

console.log(out)

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

{
  type: 'root',
  children: [
    {
      type: 'paragraph',
      children: [
        {type: 'text', value: 'A lovely language know as '},
        {
          type: 'textDirective',
          name: 'abbr',
          attributes: {title: 'HyperText Markup Language'},
          children: [{type: 'text', value: 'HTML'}]
        },
        {type: 'text', value: '.'}
      ]
    }
  ]
}
A lovely language know as :abbr[HTML]{title="HyperText Markup Language"}.

API

This package exports the identifiers directiveFromMarkdown and directiveToMarkdown. There is no default export.

directiveFromMarkdown()

Create an extension for mdast-util-from-markdown to enable directives in markdown.

Returns

Extension for mdast-util-from-markdown to enable directives (FromMarkdownExtension).

directiveToMarkdown()

Create an extension for mdast-util-to-markdown to enable directives in markdown.

There are no options, but passing options.quote to mdast-util-to-markdown is honored for attributes.

Returns

Extension for mdast-util-to-markdown to enable directives (ToMarkdownExtension).

ContainerDirective

Directive in flow content (such as in the root document, or block quotes), which contains further flow content (TypeScript type).

Type
import type {BlockContent, DefinitionContent, Parent} from 'mdast'

interface ContainerDirective extends Parent {
  type: 'containerDirective'
  name: string
  attributes?: Record<string, string | null | undefined> | null | undefined
  children: Array<BlockContent | DefinitionContent>
}

Directives

The different directive nodes (TypeScript type).

Type
type Directives = ContainerDirective | LeafDirective | TextDirective

LeafDirective

Directive in flow content (such as in the root document, or block quotes), which contains nothing (TypeScript type).

Type
import type {PhrasingContent, Parent} from 'mdast'

interface LeafDirective extends Parent {
  type: 'leafDirective'
  name: string
  attributes?: Record<string, string | null | undefined> | null | undefined
  children: Array<PhrasingContent>
}

TextDirective

Directive in phrasing content (such as in paragraphs, headings) (TypeScript type).

Type
import type {PhrasingContent, Parent} from 'mdast'

interface TextDirective extends Parent {
  type: 'textDirective'
  name: string
  attributes?: Record<string, string | null | undefined> | null | undefined
  children: Array<PhrasingContent>
}

HTML

This utility does not handle how markdown is turned to HTML. You can use this with some more code to match your specific needs, to allow for anything from callouts, citations, styled blocks, forms, embeds, spoilers, etc. Traverse the tree to change directives to whatever you please.

Syntax

See Syntax in micromark-extension-directive.

Syntax tree

The following interfaces are added to mdast by this utility.

Nodes

TextDirective

interface TextDirective <: Parent {
  type: 'textDirective'
  children: [PhrasingContent]
}

TextDirective includes Directive

TextDirective (Parent) is a directive. It can be used where phrasing content is expected. Its content model is also phrasing content. It includes the mixin Directive.

For example, the following Markdown:

:name[Label]{#x.y.z key=value}

Yields:

{
  type: 'textDirective',
  name: 'name',
  attributes: {id: 'x', class: 'y z', key: 'value'},
  children: [{type: 'text', value: 'Label'}]
}

LeafDirective

interface LeafDirective <: Parent {
  type: 'leafDirective'
  children: [PhrasingContent]
}

LeafDirective includes Directive

LeafDirective (Parent) is a directive. It can be used where flow content is expected. Its content model is phrasing content. It includes the mixin Directive.

For example, the following Markdown:

::youtube[Label]{v=123}

Yields:

{
  type: 'leafDirective',
  name: 'youtube',
  attributes: {v: '123'},
  children: [{type: 'text', value: 'Label'}]
}

ContainerDirective

interface ContainerDirective <: Parent {
  type: 'containerDirective'
  children: [FlowContent]
}

ContainerDirective includes Directive

ContainerDirective (Parent) is a directive. It can be used where flow content is expected. Its content model is also flow content. It includes the mixin Directive.

The phrasing in the label is, when available, added as a paragraph with a directiveLabel: true field, as the head of its content.

For example, the following Markdown:

:::spoiler[Open at your own peril]
He dies.
:::

Yields:

{
  type: 'containerDirective',
  name: 'spoiler',
  attributes: {},
  children: [
    {
      type: 'paragraph',
      data: {directiveLabel: true},
      children: [{type: 'text', value: 'Open at your own peril'}]
    },
    {
      type: 'paragraph',
      children: [{type: 'text', value: 'He dies.'}]
    }
  ]
}

Mixin

Directive

interface mixin Directive {
  name: string
  attributes: Attributes?
}

interface Attributes {}
typedef string AttributeName
typedef string AttributeValue

Directive represents something defined by an extension.

The name field must be present and represents an identifier of an extension.

The attributes field represents information associated with the node. The value of the attributes field implements the Attributes interface.

In the Attributes interface, every field must be an AttributeName and every value an AttributeValue. The fields and values can be anything: there are no semantics (such as by HTML or hast).

In JSON, the value null must be treated as if the attribute was not included. In JavaScript, both null and undefined must be similarly ignored.

Types

This package is fully typed with TypeScript. It exports the additional types ContainerDirective, Directives, LeafDirective, and TextDirective.

It also registers the node types with @types/mdast. If you’re working with the syntax tree, make sure to import this utility somewhere in your types, as that registers the new node types in the tree.

/**
 * @typedef {import('mdast-util-directive')}
 */

import {visit} from 'unist-util-visit'

/** @type {import('mdast').Root} */
const tree = getMdastNodeSomeHow()

visit(tree, function (node) {
  // `node` can now be one of the nodes for directives.
})

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-directive@^3, compatible with Node.js 16.

This utility works with mdast-util-from-markdown version 2+ and mdast-util-to-markdown version 2+.

Related

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