497 lines
12 KiB
Markdown
497 lines
12 KiB
Markdown
# mdast-util-mdx-expression
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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 [MDX][] expressions (`{Math.PI}`).
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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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* [`mdxExpressionFromMarkdown`](#mdxexpressionfrommarkdown)
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* [`mdxExpressionToMarkdown`](#mdxexpressiontomarkdown)
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* [`MdxFlowExpression`](#mdxflowexpression)
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* [`MdxTextExpression`](#mdxtextexpression)
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* [`MdxFlowExpressionHast`](#mdxflowexpressionhast)
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* [`MdxTextExpressionHast`](#mdxtextexpressionhast)
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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 MDX expression syntax
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in 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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expressions 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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expressions in syntax trees to markdown).
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## When to use this
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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-mdx-expression`][extension].
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When you are working with syntax trees and want all of MDX, use
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[`mdast-util-mdx`][mdast-util-mdx] instead.
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All these packages are used in [`remark-mdx`][remark-mdx], 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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## Install
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This package is [ESM only][esm].
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In Node.js (version 14.14+ and 16.0+), install with [npm][]:
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```sh
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npm install mdast-util-mdx-expression
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```
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In Deno with [`esm.sh`][esmsh]:
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```js
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import {mdxExpressionFromMarkdown, mdxExpressionToMarkdown} from 'https://esm.sh/mdast-util-mdx-expression@1'
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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 {mdxExpressionFromMarkdown, mdxExpressionToMarkdown} from 'https://esm.sh/mdast-util-mdx-expression@1?bundle'
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</script>
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```
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## Use
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Say our document `example.mdx` contains:
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```mdx
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{
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a + 1
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}
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b {true}.
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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 * as acorn from 'acorn'
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import {fromMarkdown} from 'mdast-util-from-markdown'
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import {toMarkdown} from 'mdast-util-to-markdown'
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import {mdxExpression} from 'micromark-extension-mdx-expression'
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import {mdxExpressionFromMarkdown, mdxExpressionToMarkdown} from 'mdast-util-mdx-expression'
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const doc = await fs.readFile('example.mdx')
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const tree = fromMarkdown(doc, {
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extensions: [mdxExpression({acorn, addResult: true})],
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mdastExtensions: [mdxExpressionFromMarkdown]
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})
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console.log(tree)
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const out = toMarkdown(tree, {extensions: [mdxExpressionToMarkdown]})
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console.log(out)
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```
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…now running `node example.js` yields (positional info removed for 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: 'mdxFlowExpression',
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value: '\na + 1\n',
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data: {
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estree: {
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type: 'Program',
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body: [
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{
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type: 'ExpressionStatement',
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expression: {
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type: 'BinaryExpression',
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left: {type: 'Identifier', name: 'a'},
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operator: '+',
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right: {type: 'Literal', value: 1, raw: '1'}
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}
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}
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],
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sourceType: 'module'
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}
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}
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},
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{
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type: 'paragraph',
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children: [
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{type: 'text', value: 'b '},
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{
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type: 'mdxTextExpression',
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value: 'true',
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data: {
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estree: {
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type: 'Program',
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body: [
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{
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type: 'ExpressionStatement',
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expression: {type: 'Literal', value: true, raw: 'true'}
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}
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],
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sourceType: 'module'
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}
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}
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},
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{type: 'text', value: '.'}
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]
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}
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]
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}
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```
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```markdown
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{
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a + 1
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}
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b {true}.
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```
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## API
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This package exports the identifiers
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[`mdxExpressionFromMarkdown`][api-mdx-expression-from-markdown] and
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[`mdxExpressionToMarkdown`][api-mdx-expression-to-markdown].
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There is no default export.
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### `mdxExpressionFromMarkdown`
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Extension for [`mdast-util-from-markdown`][mdast-util-from-markdown] to enable
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MDX expressions.
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When using the [micromark syntax extension][extension] with `addResult`, nodes
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will have a `data.estree` field set to an ESTree [`Program`][program] node.
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### `mdxExpressionToMarkdown`
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Extension for [`mdast-util-to-markdown`][mdast-util-to-markdown] to enable MDX
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expressions.
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### `MdxFlowExpression`
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MDX expression node, occurring in flow (block) (TypeScript type).
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###### Type
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```ts
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import type {Program} from 'estree-jsx'
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import type {Literal} from 'mdast'
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interface MdxFlowExpression extends Literal {
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type: 'mdxFlowExpression'
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data?: {estree?: Program | null | undefined} & Literal['data']
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}
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```
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### `MdxTextExpression`
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MDX expression node, occurring in text (block) (TypeScript type).
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###### Type
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```ts
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import type {Program} from 'estree-jsx'
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import type {Literal} from 'mdast'
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interface MdxTextExpression extends Literal {
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type: 'mdxTextExpression'
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data?: {estree?: Program | null | undefined} & Literal['data']
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}
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```
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### `MdxFlowExpressionHast`
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Same as [`MdxFlowExpression`][api-mdx-flow-expression], but registered with
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`@types/hast` (TypeScript type).
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###### Type
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```ts
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import type {Program} from 'estree-jsx'
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import type {Literal} from 'hast'
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interface MdxFlowExpressionHast extends Literal {
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type: 'mdxFlowExpression'
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data?: {estree?: Program | null | undefined} & Literal['data']
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}
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```
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### `MdxTextExpressionHast`
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Same as [`MdxTextExpression`][api-mdx-text-expression], but registered with
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`@types/hast` (TypeScript type).
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###### Type
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```ts
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import type {Program} from 'estree-jsx'
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import type {Literal} from 'hast'
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interface MdxTextExpressionHast extends Literal {
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type: 'mdxTextExpression'
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data?: {estree?: Program | null | undefined} & Literal['data']
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}
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```
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## HTML
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MDX expressions have no representation in HTML.
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Though, when you are dealing with MDX, you will likely go *through* hast.
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You can enable passing MDX expressions through to hast by configuring
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[`mdast-util-to-hast`][mdast-util-to-hast] with
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`passThrough: ['mdxFlowExpression', 'mdxTextExpression']`.
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## Syntax
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See [Syntax in `micromark-extension-mdx-expression`][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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#### `MdxFlowExpression`
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```idl
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interface MdxFlowExpression <: Literal {
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type: "mdxFlowExpression"
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}
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```
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**MdxFlowExpression** (**[Literal][dfn-literal]**) represents a JavaScript
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expression embedded in flow (block).
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It 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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For example, the following markdown:
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```markdown
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{
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1 + 1
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}
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```
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Yields:
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```js
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{type: 'mdxFlowExpression', value: '\n1 + 1\n'}
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```
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#### `MdxTextExpression`
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```idl
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interface MdxTextExpression <: Literal {
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type: "mdxTextExpression"
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}
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```
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**MdxTextExpression** (**[Literal][dfn-literal]**) represents a JavaScript
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expression embedded in text (span, inline).
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It can be used where **[phrasing][dfn-phrasing-content]** content is expected.
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Its content is represented by its `value` field.
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For example, the following markdown:
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```markdown
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a {1 + 1} b.
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```
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Yields:
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```js
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{type: 'mdxTextExpression', value: '1 + 1'}
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```
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### Content model
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#### `FlowContent` (MDX expression)
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```idl
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type FlowContentMdxExpression = MdxFlowExpression | FlowContent
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```
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#### `PhrasingContent` (MDX expression)
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```idl
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type PhrasingContentMdxExpression = MdxTextExpression | 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 [`MdxFlowExpression`][api-mdx-flow-expression],
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[`MdxFlowExpressionHast`][api-mdx-flow-expression-hast],
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[`MdxTextExpression`][api-mdx-text-expression], and
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[`MdxTextExpressionHast`][api-mdx-text-expression-hast].
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It also registers the node types with `@types/mdast` and `@types/hast`.
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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-mdx-expression')}
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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, (node) => {
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// `node` can now be an expression node.
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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 all maintained
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versions of Node.js.
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As of now, that is Node.js 14.14+ and 16.0+.
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Our projects sometimes work with older versions, but this is not guaranteed.
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This plugin works with `mdast-util-from-markdown` version 1+ and
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`mdast-util-to-markdown` version 1+.
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## Related
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* [`remarkjs/remark-mdx`][remark-mdx]
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— remark plugin to support MDX
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* [`syntax-tree/mdast-util-mdx`][mdast-util-mdx]
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— mdast utility to support MDX
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* [`micromark/micromark-extension-mdx-expression`][extension]
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— micromark extension to parse MDX expressions
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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-mdx-expression/workflows/main/badge.svg
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[build]: https://github.com/syntax-tree/mdast-util-mdx-expression/actions
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[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/mdast-util-mdx-expression.svg
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[coverage]: https://codecov.io/github/syntax-tree/mdast-util-mdx-expression
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[downloads-badge]: https://img.shields.io/npm/dm/mdast-util-mdx-expression.svg
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[downloads]: https://www.npmjs.com/package/mdast-util-mdx-expression
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[size-badge]: https://img.shields.io/bundlephobia/minzip/mdast-util-mdx-expression.svg
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[size]: https://bundlephobia.com/result?p=mdast-util-mdx-expression
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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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[mdast]: https://github.com/syntax-tree/mdast
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[mdast-util-to-hast]: https://github.com/syntax-tree/mdast-util-to-hast
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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-mdx]: https://github.com/syntax-tree/mdast-util-mdx
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[extension]: https://github.com/micromark/micromark-extension-mdx-expression
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[syntax]: https://github.com/micromark/micromark-extension-mdx-expression#syntax
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[program]: https://github.com/estree/estree/blob/master/es2015.md#programs
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[dfn-literal]: https://github.com/syntax-tree/mdast#literal
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[remark-mdx]: https://mdxjs.com/packages/remark-mdx/
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[mdx]: https://mdxjs.com
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[api-mdx-expression-from-markdown]: #mdxexpressionfrommarkdown
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[api-mdx-expression-to-markdown]: #mdxexpressiontomarkdown
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[api-mdx-flow-expression]: #mdxflowexpression
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[api-mdx-text-expression]: #mdxtextexpression
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[api-mdx-flow-expression-hast]: #mdxflowexpressionhast
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[api-mdx-text-expression-hast]: #mdxtextexpressionhast
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[dfn-flow-content]: #flowcontent-mdx-expression
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[dfn-phrasing-content]: #phrasingcontent-mdx-expression
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