509 lines
13 KiB
Markdown
509 lines
13 KiB
Markdown
# remark-directive
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[![Build][build-badge]][build]
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[![Coverage][coverage-badge]][coverage]
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[![Downloads][downloads-badge]][downloads]
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[![Size][size-badge]][size]
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[![Sponsors][sponsors-badge]][collective]
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[![Backers][backers-badge]][collective]
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[![Chat][chat-badge]][chat]
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**[remark][]** plugin to support the [generic directives
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proposal][commonmark-prop] (`:cite[smith04]`,
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`::youtube[Video of a cat in a box]{v=01ab2cd3efg}`, and such).
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## Contents
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* [What is this?](#what-is-this)
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* [When should I use this?](#when-should-i-use-this)
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* [Install](#install)
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* [Use](#use)
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* [API](#api)
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* [`unified().use(remarkDirective)`](#unifieduseremarkdirective)
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* [Examples](#examples)
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* [Example: YouTube](#example-youtube)
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* [Example: Styled blocks](#example-styled-blocks)
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* [Authoring](#authoring)
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* [HTML](#html)
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* [CSS](#css)
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* [Syntax](#syntax)
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* [Syntax tree](#syntax-tree)
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* [Types](#types)
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* [Compatibility](#compatibility)
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* [Security](#security)
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* [Related](#related)
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* [Contribute](#contribute)
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* [License](#license)
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## What is this?
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This package is a [unified][] ([remark][]) plugin to add support for directives:
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one syntax for arbitrary extensions in markdown.
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## When should I use this?
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Directives are one of the four ways to extend markdown: an arbitrary extension
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syntax (see [Extending markdown][micromark-extending-markdown] in micromark’s
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docs for the alternatives and more info).
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This mechanism works well when you control the content: who authors it, what
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tools handle it, and where it’s displayed.
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When authors can read a guide on how to embed a tweet but are not expected to
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know the ins and outs of HTML or JavaScript.
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Directives don’t work well if you don’t know who authors content, what tools
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handle it, and where it ends up.
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Example use cases are a docs website for a project or product, or blogging
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tools and static site generators.
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If you *just* want to turn markdown into HTML (with maybe a few extensions such
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as this one), we recommend [`micromark`][micromark] with
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[`micromark-extension-directive`][micromark-extension-directive] instead.
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If you don’t use plugins and want to access the syntax tree, you can use
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[`mdast-util-from-markdown`][mdast-util-from-markdown] with
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[`mdast-util-directive`][mdast-util-directive].
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## Install
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This package is [ESM only][esm].
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In Node.js (version 16+), install with [npm][]:
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```sh
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npm install remark-directive
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```
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In Deno with [`esm.sh`][esmsh]:
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```js
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import remarkDirective from 'https://esm.sh/remark-directive@3'
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```
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In browsers with [`esm.sh`][esmsh]:
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```html
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<script type="module">
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import remarkDirective from 'https://esm.sh/remark-directive@3?bundle'
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</script>
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```
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## Use
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Say our document `example.md` contains:
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```markdown
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:::main{#readme}
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Lorem:br
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ipsum.
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::hr{.red}
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A :i[lovely] language know as :abbr[HTML]{title="HyperText Markup Language"}.
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:::
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```
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…and our module `example.js` contains:
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```js
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// Register `hName`, `hProperties` types, used when turning markdown to HTML:
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/// <reference types="mdast-util-to-hast" />
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// Register directive nodes in mdast:
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/// <reference types="mdast-util-directive" />
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import {h} from 'hastscript'
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import rehypeFormat from 'rehype-format'
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import rehypeStringify from 'rehype-stringify'
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import remarkDirective from 'remark-directive'
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import remarkParse from 'remark-parse'
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import remarkRehype from 'remark-rehype'
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import {read} from 'to-vfile'
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import {unified} from 'unified'
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import {visit} from 'unist-util-visit'
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const file = await unified()
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.use(remarkParse)
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.use(remarkDirective)
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.use(myRemarkPlugin)
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.use(remarkRehype)
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.use(rehypeFormat)
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.use(rehypeStringify)
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.process(await read('example.md'))
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console.log(String(file))
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// This plugin is an example to let users write HTML with directives.
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// It’s informative but rather useless.
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// See below for others examples.
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function myRemarkPlugin() {
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/**
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* @param {import('mdast').Root} tree
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* Tree.
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* @returns {undefined}
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* Nothing.
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*/
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return function (tree) {
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visit(tree, function (node) {
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if (
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node.type === 'containerDirective' ||
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node.type === 'leafDirective' ||
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node.type === 'textDirective'
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) {
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const data = node.data || (node.data = {})
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const hast = h(node.name, node.attributes || {})
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data.hName = hast.tagName
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data.hProperties = hast.properties
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}
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})
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}
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}
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```
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…then running `node example.js` yields:
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```html
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<main id="readme">
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<p>Lorem<br>ipsum.</p>
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<hr class="red">
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<p>A <i>lovely</i> language know as <abbr title="HyperText Markup Language">HTML</abbr>.</p>
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</main>
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```
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## API
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This package exports no identifiers.
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The default export is [`remarkDirective`][api-remark-directive].
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### `unified().use(remarkDirective)`
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Add support for generic directives.
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###### Parameters
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There are no parameters.
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###### Returns
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Nothing (`undefined`).
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###### Notes
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Doesn’t handle the directives:
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[create your own plugin][unified-create-plugin] to do that.
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## Examples
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### Example: YouTube
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This example shows how directives can be used for YouTube embeds.
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It’s based on the example in Use above.
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If `myRemarkPlugin` was replaced with this function:
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```js
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// Register `hName`, `hProperties` types, used when turning markdown to HTML:
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/// <reference types="mdast-util-to-hast" />
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// Register directive nodes in mdast:
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/// <reference types="mdast-util-directive" />
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import {visit} from 'unist-util-visit'
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// This plugin is an example to turn `::youtube` into iframes.
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function myRemarkPlugin() {
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/**
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* @param {import('mdast').Root} tree
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* Tree.
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* @param {import('vfile').VFile} file
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* File.
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* @returns {undefined}
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* Nothing.
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*/
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return (tree, file) => {
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visit(tree, function (node) {
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if (
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node.type === 'containerDirective' ||
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node.type === 'leafDirective' ||
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node.type === 'textDirective'
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) {
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if (node.name !== 'youtube') return
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const data = node.data || (node.data = {})
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const attributes = node.attributes || {}
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const id = attributes.id
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if (node.type === 'textDirective') {
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file.fail(
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'Unexpected `:youtube` text directive, use two colons for a leaf directive',
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node
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)
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}
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if (!id) {
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file.fail('Unexpected missing `id` on `youtube` directive', node)
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}
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data.hName = 'iframe'
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data.hProperties = {
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src: 'https://www.youtube.com/embed/' + id,
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width: 200,
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height: 200,
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frameBorder: 0,
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allow: 'picture-in-picture',
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allowFullScreen: true
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}
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}
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})
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}
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}
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```
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…and `example.md` contains:
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```markdown
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# Cat videos
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::youtube[Video of a cat in a box]{#01ab2cd3efg}
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```
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…then running `node example.js` yields:
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```html
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<h1>Cat videos</h1>
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<iframe src="https://www.youtube.com/embed/01ab2cd3efg" width="200" height="200" frameborder="0" allow="picture-in-picture" allowfullscreen>Video of a cat in a box</iframe>
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```
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### Example: Styled blocks
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> 👉 **Note**: This is sometimes called admonitions, callouts, etc.
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This example shows how directives can be used to style blocks.
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It’s based on the example in Use above.
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If `myRemarkPlugin` was replaced with this function:
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```js
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// Register `hName`, `hProperties` types, used when turning markdown to HTML:
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/// <reference types="mdast-util-to-hast" />
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// Register directive nodes in mdast:
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/// <reference types="mdast-util-directive" />
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import {h} from 'hastscript'
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import {visit} from 'unist-util-visit'
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// This plugin is an example to turn `::note` into divs, passing arbitrary
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// attributes.
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function myRemarkPlugin() {
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/**
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* @param {import('mdast').Root} tree
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* Tree.
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* @returns {undefined}
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* Nothing.
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*/
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return (tree) => {
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visit(tree, (node) => {
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if (
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node.type === 'containerDirective' ||
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node.type === 'leafDirective' ||
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node.type === 'textDirective'
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) {
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if (node.name !== 'note') return
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const data = node.data || (node.data = {})
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const tagName = node.type === 'textDirective' ? 'span' : 'div'
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data.hName = tagName
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data.hProperties = h(tagName, node.attributes || {}).properties
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}
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})
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}
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}
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```
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…and `example.md` contains:
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```markdown
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# How to use xxx
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You can use xxx.
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:::note{.warning}
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if you chose xxx, you should also use yyy somewhere…
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:::
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```
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…then running `node example` yields:
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```html
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<h1>How to use xxx</h1>
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<p>You can use xxx.</p>
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<div class="warning">
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<p>if you chose xxx, you should also use yyy somewhere…</p>
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</div>
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```
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## Authoring
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When authoring markdown with directives, keep in mind that they don’t work in
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most places.
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On your own site it can be great!
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## HTML
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You can define how directives are turned into HTML.
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If directives are not handled, they do not emit anything.
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## CSS
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How to display directives is left as an exercise for the reader.
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## Syntax
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See [*Syntax* in
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`micromark-extension-directive`](https://github.com/micromark/micromark-extension-directive#syntax).
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## Syntax tree
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See [*Syntax tree* in
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`mdast-util-directive`](https://github.com/syntax-tree/mdast-util-directive#syntax-tree).
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## Types
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This package is fully typed with [TypeScript][].
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It exports no additional options.
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If you’re working with the syntax tree, you can register the new node types
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with `@types/mdast` by adding a reference:
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```js
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// Register directive nodes in mdast:
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/// <reference types="mdast-util-directive" />
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import {visit} from 'unist-util-visit'
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function myRemarkPlugin() {
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/**
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* @param {import('mdast').Root} tree
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* Tree.
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* @returns {undefined}
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* Nothing.
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*/
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return (tree) => {
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visit(tree, function (node) {
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console.log(node) // `node` can now be one of the nodes for directives.
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})
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}
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}
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```
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## Compatibility
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Projects maintained by the unified collective are compatible with maintained
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versions of Node.js.
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When we cut a new major release, we drop support for unmaintained versions of
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Node.
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This means we try to keep the current release line, `remark-directive@^3`,
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compatible with Node.js 16.
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## Security
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Use of `remark-directive` does not involve **[rehype][]** ([hast][]) or user
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content so there are no openings for [cross-site scripting (XSS)][wiki-xss]
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attacks.
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## Related
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* [`remark-gfm`](https://github.com/remarkjs/remark-gfm)
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— support GFM (autolink literals, footnotes, strikethrough, tables,
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tasklists)
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* [`remark-frontmatter`](https://github.com/remarkjs/remark-frontmatter)
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— support frontmatter (YAML, TOML, and more)
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* [`remark-math`](https://github.com/remarkjs/remark-math)
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— support math
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* [`remark-mdx`](https://github.com/mdx-js/mdx/tree/main/packages/remark-mdx)
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— support MDX (ESM, JSX, expressions)
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## Contribute
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See [`contributing.md`][contributing] in [`remarkjs/.github`][health] for ways
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to get started.
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See [`support.md`][support] for ways to get help.
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This project has a [code of conduct][coc].
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By interacting with this repository, organization, or community you agree to
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abide by its terms.
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## License
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[MIT][license] © [Titus Wormer][author]
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<!-- Definitions -->
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[build-badge]: https://github.com/remarkjs/remark-directive/workflows/main/badge.svg
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[build]: https://github.com/remarkjs/remark-directive/actions
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[coverage-badge]: https://img.shields.io/codecov/c/github/remarkjs/remark-directive.svg
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[coverage]: https://codecov.io/github/remarkjs/remark-directive
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[downloads-badge]: https://img.shields.io/npm/dm/remark-directive.svg
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[downloads]: https://www.npmjs.com/package/remark-directive
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[size-badge]: https://img.shields.io/bundlejs/size/remark-directive
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[size]: https://bundlejs.com/?q=remark-directive
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[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg
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[backers-badge]: https://opencollective.com/unified/backers/badge.svg
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[collective]: https://opencollective.com/unified
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[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg
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[chat]: https://github.com/remarkjs/remark/discussions
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[npm]: https://docs.npmjs.com/cli/install
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[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
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[esmsh]: https://esm.sh
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[health]: https://github.com/remarkjs/.github
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[contributing]: https://github.com/remarkjs/.github/blob/main/contributing.md
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[support]: https://github.com/remarkjs/.github/blob/main/support.md
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[coc]: https://github.com/remarkjs/.github/blob/main/code-of-conduct.md
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[license]: license
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[author]: https://wooorm.com
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[commonmark-prop]: https://talk.commonmark.org/t/generic-directives-plugins-syntax/444
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[hast]: https://github.com/syntax-tree/hast
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[mdast-util-directive]: https://github.com/syntax-tree/mdast-util-directive
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[mdast-util-from-markdown]: https://github.com/syntax-tree/mdast-util-from-markdown
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[micromark]: https://github.com/micromark/micromark
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[micromark-extension-directive]: https://github.com/micromark/micromark-extension-directive
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[micromark-extending-markdown]: https://github.com/micromark/micromark#extending-markdown
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[rehype]: https://github.com/rehypejs/rehype
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[remark]: https://github.com/remarkjs/remark
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[typescript]: https://www.typescriptlang.org
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[unified]: https://github.com/unifiedjs/unified
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[unified-create-plugin]: https://unifiedjs.com/learn/guide/create-a-plugin/
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[wiki-xss]: https://en.wikipedia.org/wiki/Cross-site_scripting
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[api-remark-directive]: #unifieduseremarkdirective
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