Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.
Awesome Lists | Featured Topics | Projects
https://github.com/micromark/micromark-extension-mdx-jsx

micromark extension to support MDX or MDX.js JSX
https://github.com/micromark/micromark-extension-mdx-jsx
jsx mdx mdxjs micromark micromark-extension
Last synced: 5 days ago
JSON representation
micromark extension to support MDX or MDX.js JSX
Host: GitHub
URL: https://github.com/micromark/micromark-extension-mdx-jsx
Owner: micromark
License: mit
Created: 2020-12-06T17:45:57.000Z (about 4 years ago)
Default Branch: main
Last Pushed: 2024-09-02T14:30:16.000Z (4 months ago)
Last Synced: 2025-01-02T05:12:13.473Z (12 days ago)
Topics: jsx, mdx, mdxjs, micromark, micromark-extension
Language: JavaScript
Homepage: https://unifiedjs.com
Size: 200 KB
Stars: 9
Watchers: 7
Forks: 4
Open Issues: 1
Metadata Files:
- Readme: readme.md
- License: license
Awesome Lists containing this project

README

        # micromark-extension-mdx-jsx

[![Build][build-badge]][build]

[![Coverage][coverage-badge]][coverage]

[![Downloads][downloads-badge]][downloads]

[![Size][size-badge]][size]

[![Sponsors][sponsors-badge]][collective]

[![Backers][backers-badge]][collective]

[![Chat][chat-badge]][chat]

[micromark][] extension to support [MDX][mdxjs] JSX (``).

## Contents

* [What is this?](#what-is-this)

* [When to use this](#when-to-use-this)

* [Install](#install)

* [Use](#use)

* [API](#api)

  * [`mdxJsx(options?)`](#mdxjsxoptions)

  * [`Options`](#options)

* [Authoring](#authoring)

* [Syntax](#syntax)

* [Errors](#errors)

  * [Unexpected end of file $at, expected $expect](#unexpected-end-of-file-at-expected-expect)

  * [Unexpected character $at, expected $expect](#unexpected-character-at-expected-expect)

  * [Unexpected lazy line in container, expected line to be…](#unexpected-lazy-line-in-container-expected-line-to-be)

* [Tokens](#tokens)

* [Types](#types)

* [Compatibility](#compatibility)

* [Security](#security)

* [Related](#related)

* [Contribute](#contribute)

* [License](#license)

## What is this?

This package contains an extension that adds support for the JSX syntax enabled

by [MDX][mdxjs] to [`micromark`][micromark].

These extensions are used inside MDX.

It mostly matches how JSX works in most places that support it (TypeScript,

Babel, esbuild, SWC, etc).

This package can be made aware or unaware of JavaScript syntax.

When unaware, expressions could include Rust or variables or whatnot.

## When to use this

This project is useful when you want to support JSX in markdown.

You can use this extension when you are working with [`micromark`][micromark].

To support all MDX features, use

[`micromark-extension-mdxjs`][micromark-extension-mdxjs] instead.

When you need a syntax tree, combine this package with

[`mdast-util-mdx-jsx`][mdast-util-mdx-jsx].

All these packages are used in [`remark-mdx`][remark-mdx], which focusses on

making it easier to transform content by abstracting these internals away.

When you are using [`mdx-js/mdx`][mdxjs], all of this is already included.

## Install

This package is [ESM only][esm].

In Node.js (version 16+), install with [npm][]:

```sh

npm install micromark-extension-mdx-jsx

```

In Deno with [`esm.sh`][esmsh]:

```js

import {mdxJsx} from 'https://esm.sh/micromark-extension-mdx-jsx@2'

```

In browsers with [`esm.sh`][esmsh]:

```html

  import {mdxJsx} from 'https://esm.sh/micromark-extension-mdx-jsx@2?bundle'

```

## Use

```js

import {micromark} from 'micromark'

import {mdxJsx} from 'micromark-extension-mdx-jsx'

const output = micromark('a  f', {extensions: [mdxJsx()]})

console.log(output)

```

Yields:

```html

a  f

```

…which is useless: go to a syntax tree with

[`mdast-util-from-markdown`][mdast-util-from-markdown] and

[`mdast-util-mdx-jsx`][mdast-util-mdx-jsx] instead.

## API

This package exports the identifier [`mdxJsx`][api-mdx-jsx].

There is no default export.

The export map supports the [`development` condition][development].

Run `node --conditions development module.js` to get instrumented dev code.

Without this condition, production code is loaded.

### `mdxJsx(options?)`

Create an extension for `micromark` to enable MDX JSX syntax.

###### Parameters

* `options` ([`Options`][api-options], optional)

  — configuration

###### Returns

Extension for `micromark` that can be passed in `extensions` to enable MDX

JSX syntax ([`Extension`][micromark-extension]).

### `Options`

Configuration (TypeScript type).

###### Fields

* `acorn` ([`Acorn`][acorn], optional)

  — acorn parser to use

* `acornOptions` ([`AcornOptions`][acorn-options], default:

  `{ecmaVersion: 2024, locations: true, sourceType: 'module'}`)

  — configuration for acorn; all fields except `locations` can be set

* `addResult` (`boolean`, default: `false`)

  — whether to add `estree` fields to tokens with results from acorn

## Authoring

When authoring markdown with JSX, keep in mind that MDX is a whitespace

sensitive and line-based language, while JavaScript is insensitive to

whitespace.

This affects how markdown and JSX interleave with eachother in MDX.

For more info on how it works, see [§ Interleaving][mdxjs-interleaving] on the

MDX site.

###### Comments inside tags

JavaScript comments in JSX are not supported.

Incorrect:

```mdx-invalid

```

Correct:

```mdx

```

A PR that adds support for them would be accepted.

###### Element or fragment attribute values

JSX elements or JSX fragments as attribute values are not supported.

The reason for this change is that it would be confusing whether markdown

would work.

Incorrect:

```mdx-invalid

Venus> />

Pluto />

```

Correct:

```mdx

Jupiter} />

```

###### Greater than (`>`) and right curly brace (`}`)

JSX does not allow U+003E GREATER THAN (`>`) or U+007D RIGHT CURLY BRACE

(`}`) literally in text, they need to be encoded as character references

(or expressions).

There is no good reason for this (some JSX parsers agree with us and don’t

crash either).

Therefore, in MDX, U+003E GREATER THAN (`>`) and U+007D RIGHT CURLY BRACE

(`}`) are fine literally and don’t need to be encoded.

## Syntax

JSX forms with the following BNF:

mdx_jsx_flow ::= mdx_jsx *space_or_tab [mdx_jsx *space_or_tab]

mdx_jsx_text ::= mdx_jsx

; constraint: markdown whitespace (`space_or_tab | eol`) is NOT

; allowed directly after `<` in order to allow `1 < 3` in markdown.

mdx_jsx ::=

  '<' [closing]

  [*whitespace name [attributes_after_identifier] [closing]]

  *whitespace '>'

attributes_after_identifier ::=

  1*whitespace (attributes_boolean | attributes_value) |

  *whitespace attributes_expression |

attributes_after_value ::=

  *whitespace (attributes_boolean | attributes_expression | attributes_value)

attributes_boolean ::= key [attributes_after_identifier]

; Note: in gnostic mode the value of the expression must instead be a single valid ES spread

; expression

attributes_expression ::= expression [attributes_after_value]

attributes_value ::= key initializer [attributes_after_value]

closing ::= *whitespace '/'

name ::= identifier [local | members]

key ::= identifier [local]

local ::= *whitespace ':' *whitespace identifier

members ::= member *member

member ::= *whitespace '.' *whitespace identifier

identifier ::= identifier_start *identifier_part

initializer ::= *whitespace '=' *whitespace value

value ::= double_quoted | single_quoted | expression

; Note: in gnostic mode the value must instead be a single valid ES expression

expression ::= '{' *(expression_text | expression) '}'

double_quoted ::= '"' *double_quoted_text '"'

single_quoted ::= "'" *single_quoted_text "'"

whitespace ::= es_whitespace

double_quoted_text ::= char - '"'

single_quoted_text ::= char - "'"

expression_text ::= char - '{' - '}'

identifier_start ::= es_identifier_start

identifier_part ::= es_identifier_part | '-'

space_or_tab ::= '\t' | ' '

eol ::= '\n' | '\r' | '\r\n'

; ECMAScript

; See “IdentifierStart”: <https://tc39.es/ecma262/#prod-IdentifierStart>

es_identifier_start ::= ?

; See “IdentifierPart”: <https://tc39.es/ecma262/#prod-IdentifierPart>

es_identifier_part ::= ?

; See “Whitespace”: <https://tc39.es/ecma262/#prod-WhiteSpace>

es_whitespace ::= ?



As the flow construct occurs in flow, like all flow constructs, it must be

followed by an eol (line ending) or eof (end of file).

The grammar for JSX in markdown is much stricter than that of HTML in

markdown.

The primary benefit of this is that tags are parsed into tokens, and thus

can be processed.

Another, arguable, benefit of this is that it comes with syntax errors: if

an author types something that is nonsensical, an error is thrown with

information about where it happened, what occurred, and what was expected

instead.

This extension supports expressions both aware and unaware to JavaScript

(respectively gnostic and agnostic).

Depending on whether acorn is passed, either valid JavaScript must be used in

expressions, or arbitrary text (such as Rust code or so) can be used.

More on this can be found in

[§ Syntax of `micromark-extension-mdx-expression`][expression-syntax].

## Errors

In aware (gnostic) mode, expressions are parsed with

[`micromark-extension-mdx-expression`][micromark-extension-mdx-expression],

which throws some more errors.

### Unexpected end of file $at, expected $expect

This error occurs for many different reasons if something was opened but not

closed (source: `micromark-extension-mdx-jsx`, rule id: `unexpected-eof`).

Some examples are:

```mdx-invalid

<

`)

* `mdxJsxTextTagAttributeValueLiteral` ^

* `mdxJsxFlowTagAttributeValueLiteralMarker` for the quotes around a string

  attribute value (`"` or `'`)

* `mdxJsxTextTagAttributeValueLiteralMarker` ^

* `mdxJsxFlowTagAttributeValueLiteralValue` for chunks of what’s inside

  string attribute values

* `mdxJsxTextTagAttributeValueLiteralValue` ^

* `mdxJsxFlowTagAttributeValueExpression` for an expression attribute value

  (``)

* `mdxJsxTextTagAttributeValueExpression` ^

* `mdxJsxFlowTagAttributeValueExpressionMarker` for the `{` and `}` of

  expression attribute values

* `mdxJsxTextTagAttributeValueExpressionMarker` ^

* `mdxJsxFlowTagAttributeValueExpressionValue` for chunks of what’s inside

  expression attribute values

* `mdxJsxTextTagAttributeValueExpressionValue` ^


## Types

This package is fully typed with [TypeScript][].

It exports the additional type [`Options`][api-options].

## Compatibility

Projects maintained by the unified collective are compatible with maintained

versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of

Node.

This means we try to keep the current release line,

`micromark-extension-mdx-jsx@^2`, compatible with Node.js 16.

This package works with `micromark` version `3` and later.

## Security

This package is safe.

## Related

* [`micromark-extension-mdxjs`][micromark-extension-mdxjs]

  — support all MDX syntax

* [`mdast-util-mdx-jsx`][mdast-util-mdx-jsx]

  — support MDX JSX in mdast

* [`remark-mdx`][remark-mdx]

  — support all MDX syntax in remark

## Contribute

See [`contributing.md` in `micromark/.github`][contributing] for ways to get

started.

See [`support.md`][support] for ways to get help.

This project has a [code of conduct][coc].

By interacting with this repository, organization, or community you agree to

abide by its terms.

## License

[MIT][license] © [Titus Wormer][author]

[build-badge]: https://github.com/micromark/micromark-extension-mdx-jsx/workflows/main/badge.svg

[build]: https://github.com/micromark/micromark-extension-mdx-jsx/actions

[coverage-badge]: https://img.shields.io/codecov/c/github/micromark/micromark-extension-mdx-jsx.svg

[coverage]: https://codecov.io/github/micromark/micromark-extension-mdx-jsx

[downloads-badge]: https://img.shields.io/npm/dm/micromark-extension-mdx-jsx.svg

[downloads]: https://www.npmjs.com/package/micromark-extension-mdx-jsx

[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=micromark-extension-mdx-jsx

[size]: https://bundlejs.com/?q=micromark-extension-mdx-jsx

[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg

[backers-badge]: https://opencollective.com/unified/backers/badge.svg

[collective]: https://opencollective.com/unified

[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg

[chat]: https://github.com/micromark/micromark/discussions

[npm]: https://docs.npmjs.com/cli/install

[esmsh]: https://esm.sh

[license]: license

[author]: https://wooorm.com

[contributing]: https://github.com/micromark/.github/blob/main/contributing.md

[support]: https://github.com/micromark/.github/blob/main/support.md

[coc]: https://github.com/micromark/.github/blob/main/code-of-conduct.md

[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c

[typescript]: https://www.typescriptlang.org

[development]: https://nodejs.org/api/packages.html#packages_resolving_user_conditions

[micromark]: https://github.com/micromark/micromark

[micromark-extension]: https://github.com/micromark/micromark#syntaxextension

[micromark-extension-mdxjs]: https://github.com/micromark/micromark-extension-mdxjs

[micromark-extension-mdx-expression]: https://github.com/micromark/micromark-extension-mdx-expression

[expression-syntax]: https://github.com/micromark/micromark-extension-mdx-expression/blob/main/packages/micromark-extension-mdx-expression/readme.md#syntax

[mdast-util-mdx-jsx]: https://github.com/syntax-tree/mdast-util-mdx-jsx

[mdast-util-from-markdown]: https://github.com/syntax-tree/mdast-util-from-markdown

[remark-mdx]: https://mdxjs.com/packages/remark-mdx/

[mdxjs]: https://mdxjs.com

[mdxjs-interleaving]: https://mdxjs.com/docs/what-is-mdx/#interleaving

[acorn]: https://github.com/acornjs/acorn

[acorn-options]: https://github.com/acornjs/acorn/blob/96c721dbf89d0ccc3a8c7f39e69ef2a6a3c04dfa/acorn/dist/acorn.d.ts#L16

[api-mdx-jsx]: #mdxjsxoptions

[api-options]: #options