490 lines
12 KiB
Markdown
490 lines
12 KiB
Markdown
# mdast-util-math
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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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[mdast][] extensions to parse and serialize math (`$C_L$`).
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## Contents
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* [What is this?](#what-is-this)
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* [When to use this](#when-to-use-this)
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* [Install](#install)
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* [Use](#use)
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* [API](#api)
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* [`mathFromMarkdown()`](#mathfrommarkdown)
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* [`mathToMarkdown(options?)`](#mathtomarkdownoptions)
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* [`InlineMath`](#inlinemath)
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* [`Math`](#math)
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* [`ToOptions`](#tooptions)
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* [HTML](#html)
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* [Syntax](#syntax)
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* [Syntax tree](#syntax-tree)
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* [Nodes](#nodes)
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* [Content model](#content-model)
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* [Types](#types)
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* [Compatibility](#compatibility)
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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 contains two extensions that add support for math syntax in
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markdown to [mdast][].
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These extensions plug into
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[`mdast-util-from-markdown`][mdast-util-from-markdown] (to support parsing
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math in markdown into a syntax tree) and
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[`mdast-util-to-markdown`][mdast-util-to-markdown] (to support serializing
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math in syntax trees to markdown).
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## When to use this
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This project is useful when you want to support math in markdown.
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Extending markdown with a syntax extension makes the markdown less portable.
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LaTeX equations are also quite hard.
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But this mechanism works well when you want authors, that have some LaTeX
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experience, to be able to embed rich diagrams of math in scientific text.
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You can use these extensions when you are working with
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`mdast-util-from-markdown` and `mdast-util-to-markdown` already.
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When working with `mdast-util-from-markdown`, you must combine this package
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with [`micromark-extension-math`][micromark-extension-math].
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When you don’t need a syntax tree, you can use [`micromark`][micromark]
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directly with
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[`micromark-extension-math`][micromark-extension-math].
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All these packages are used [`remark-math`][remark-math], which
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focusses on making it easier to transform content by abstracting these
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internals away.
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This utility adds [fields on nodes][fields] so that the utility responsible for
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turning mdast (markdown) nodes into hast (HTML) nodes,
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[`mdast-util-to-hast`][mdast-util-to-hast], turns text (inline) math nodes into
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`<code class="language-math math-inline">…</code>` and flow (block) math nodes
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into `<pre><code class="language-math math-display">…</code></pre>`.
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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 mdast-util-math
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```
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In Deno with [`esm.sh`][esmsh]:
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```js
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import {mathFromMarkdown, mathToMarkdown} from 'https://esm.sh/mdast-util-math@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 {mathFromMarkdown, mathToMarkdown} from 'https://esm.sh/mdast-util-math@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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Lift($L$) can be determined by Lift Coefficient ($C_L$) like the following
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equation.
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$$
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L = \frac{1}{2} \rho v^2 S C_L
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$$
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```
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…and our module `example.js` looks as follows:
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```js
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import fs from 'node:fs/promises'
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import {math} from 'micromark-extension-math'
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import {fromMarkdown} from 'mdast-util-from-markdown'
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import {mathFromMarkdown, mathToMarkdown} from 'mdast-util-math'
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import {toMarkdown} from 'mdast-util-to-markdown'
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const doc = await fs.readFile('example.md')
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const tree = fromMarkdown(doc, {
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extensions: [math()],
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mdastExtensions: [mathFromMarkdown()]
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})
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console.log(tree)
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const out = toMarkdown(tree, {extensions: [mathToMarkdown()]})
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console.log(out)
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```
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…now running `node example.js` yields (positional info and data removed for
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brevity):
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```js
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{
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type: 'root',
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children: [
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{
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type: 'paragraph',
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children: [
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{type: 'text', value: 'Lift('},
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{type: 'inlineMath', value: 'L', data: {/* … */}},
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{type: 'text', value: ') can be determined by Lift Coefficient ('},
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{type: 'inlineMath', value: 'C_L', data: {/* … */}},
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{type: 'text', value: ') like the following\nequation.'}
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]
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},
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{type: 'math', meta: null, value: 'L = \\frac{1}{2} \\rho v^2 S C_L', data: {/* … */}}
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]
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}
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```
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```markdown
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Lift($L$) can be determined by Lift Coefficient ($C_L$) like the following
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equation.
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$$
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L = \frac{1}{2} \rho v^2 S C_L
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$$
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```
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## API
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This package exports the identifiers
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[`mathFromMarkdown`][api-math-from-markdown]
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and [`mathToMarkdown`][api-math-to-markdown].
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There is no default export.
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### `mathFromMarkdown()`
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Create an extension for [`mdast-util-from-markdown`][mdast-util-from-markdown].
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###### Returns
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Extension for `mdast-util-from-markdown`
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([`FromMarkdownExtension`][from-markdown-extension]).
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### `mathToMarkdown(options?)`
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Create an extension for [`mdast-util-to-markdown`][mdast-util-to-markdown].
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###### Parameters
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* `options` ([`ToOptions`][api-to-options], optional)
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— configuration
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###### Returns
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Extension for `mdast-util-to-markdown`
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([`ToMarkdownExtension`][to-markdown-extension]).
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### `InlineMath`
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Math (text) (TypeScript type).
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###### Type
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```ts
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import type {Data, Literal} from 'mdast'
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interface InlineMath extends Literal {
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type: 'inlineMath'
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data?: InlineMathData | undefined
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}
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export interface InlineMathData extends Data {}
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```
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### `Math`
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Math (flow) (TypeScript type).
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###### Type
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```ts
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import type {Data, Literal} from 'mdast'
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interface Math extends Literal {
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type: 'math'
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meta?: string | null | undefined
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data?: MathData | undefined
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}
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export interface MathData extends Data {}
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```
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### `ToOptions`
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Configuration (TypeScript type).
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###### Fields
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* `singleDollarTextMath` (`boolean`, default: `true`)
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— whether to support math (text) with a single dollar.
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Single dollars work in Pandoc and many other places, but often interfere
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with “normal” dollars in text.
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If you turn this off, you can still use two or more dollars for text math
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## HTML
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This plugin integrates with [`mdast-util-to-hast`][mdast-util-to-hast].
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When mdast is turned into hast the math nodes are turned into
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`<code class="language-math math-inline">…</code>` and
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`<pre><code class="language-math math-display">…</code></pre>` elements.
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## Syntax
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See [Syntax in `micromark-extension-frontmatter`][syntax].
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## Syntax tree
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The following interfaces are added to **[mdast][]** by this utility.
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### Nodes
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#### `Math`
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```idl
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interface Math <: Literal {
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type: 'code'
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meta: string?
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}
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```
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**Math** (**[Literal][dfn-literal]**) represents a block of math,
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such as LaTeX mathematical expressions.
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**Math** can be used where **[flow][dfn-flow-content]** content is expected.
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Its content is represented by its `value` field.
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This node relates to the **[phrasing][dfn-phrasing-content]** content concept
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**[InlineMath][dfn-inline-math]**.
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A `meta` field can be present.
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It represents custom information relating to the node.
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For example, the following markdown:
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```markdown
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$$
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L = \frac{1}{2} \rho v^2 S C_L
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$$
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```
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Yields:
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```js
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{
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type: 'math',
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meta: null,
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value: 'L = \\frac{1}{2} \\rho v^2 S C_L',
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data: {/* … */}
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}
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```
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#### `InlineMath`
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```idl
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interface InlineMath <: Literal {
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type: 'inlineMath'
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}
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```
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**InlineMath** (**[Literal][dfn-literal]**) represents a fragment of computer
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code, such as a file name, computer program, or anything a computer could parse.
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**InlineMath** can be used where **[phrasing][dfn-phrasing-content]** content
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is expected.
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Its content is represented by its `value` field.
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This node relates to the **[flow][dfn-flow-content]** content concept
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**[Math][dfn-math]**.
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For example, the following markdown:
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```markdown
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$L$
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```
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Yields:
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```js
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{type: 'inlineMath', value: 'L', data: {/* … */}}
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```
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### Content model
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#### `FlowContent` (math)
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```idl
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type FlowContentMath = Math | FlowContent
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```
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#### `PhrasingContent` (math)
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```idl
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type PhrasingContentMath = InlineMath | PhrasingContent
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```
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## Types
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This package is fully typed with [TypeScript][].
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It exports the additional types [`InlineMath`][api-inline-math],
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[`Math`][api-math], and [`ToOptions`][api-to-options].
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It also registers the node types with `@types/mdast`.
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If you’re working with the syntax tree, make sure to import this utility
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somewhere in your types, as that registers the new node types in the tree.
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```js
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/**
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* @typedef {import('mdast-util-math')}
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*/
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import {visit} from 'unist-util-visit'
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/** @type {import('mdast').Root} */
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const tree = getMdastNodeSomeHow()
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visit(tree, function (node) {
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// `node` can now be one of the nodes for math.
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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, `mdast-util-math@^3`,
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compatible with Node.js 16.
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This plugin works with `mdast-util-from-markdown` version 2+ and
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`mdast-util-to-markdown` version 2+.
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## Related
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* [`remark-math`][remark-math]
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— remark plugin to support math
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* [`micromark-extension-math`][micromark-extension-math]
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— micromark extension to parse math
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## Contribute
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See [`contributing.md`][contributing] in [`syntax-tree/.github`][health] for
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ways 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/syntax-tree/mdast-util-math/workflows/main/badge.svg
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[build]: https://github.com/syntax-tree/mdast-util-math/actions
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[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/mdast-util-math.svg
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[coverage]: https://codecov.io/github/syntax-tree/mdast-util-math
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[downloads-badge]: https://img.shields.io/npm/dm/mdast-util-math.svg
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[downloads]: https://www.npmjs.com/package/mdast-util-math
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[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=mdast-util-math
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[size]: https://bundlejs.com/?q=mdast-util-math
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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/syntax-tree/unist/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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[typescript]: https://www.typescriptlang.org
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[license]: license
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[author]: https://wooorm.com
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[health]: https://github.com/syntax-tree/.github
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[contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md
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[support]: https://github.com/syntax-tree/.github/blob/main/support.md
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[coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md
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[remark-math]: https://github.com/remarkjs/remark-math
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[mdast]: https://github.com/syntax-tree/mdast
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[mdast-util-from-markdown]: https://github.com/syntax-tree/mdast-util-from-markdown
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[mdast-util-to-markdown]: https://github.com/syntax-tree/mdast-util-to-markdown
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[mdast-util-to-hast]: https://github.com/syntax-tree/mdast-util-to-hast
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[micromark]: https://github.com/micromark/micromark
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[micromark-extension-math]: https://github.com/micromark/micromark-extension-math
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[syntax]: https://github.com/micromark/micromark-extension-math#syntax
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[fields]: https://github.com/syntax-tree/mdast-util-to-hast#fields-on-nodes
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[dfn-literal]: https://github.com/syntax-tree/mdast#literal
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[from-markdown-extension]: https://github.com/syntax-tree/mdast-util-from-markdown#extension
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[to-markdown-extension]: https://github.com/syntax-tree/mdast-util-to-markdown#options
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[api-math-from-markdown]: #mathfrommarkdown
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[api-math-to-markdown]: #mathtomarkdownoptions
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[api-math]: #math
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[api-inline-math]: #inlinemath
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[api-to-options]: #tooptions
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[dfn-flow-content]: #flowcontent-math
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[dfn-phrasing-content]: #phrasingcontent-math
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[dfn-inline-math]: #inlinemath-1
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[dfn-math]: #math-1
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