mdast-util-mdx-jsx

What is mdast-util-mdx-jsx?

The mdast-util-mdx-jsx package is a utility for working with MDX (Markdown for the component era) JSX nodes within the mdast (Markdown Abstract Syntax Tree) format. It allows for parsing, manipulating, and serializing MDX JSX nodes in the context of mdast, making it a powerful tool for developers working with MDX content in JavaScript and TypeScript projects.

What are mdast-util-mdx-jsx's main functionalities?

Parsing MDX JSX nodes

This feature allows for the parsing of MDX JSX nodes from a Markdown string. The code sample demonstrates how to use the package in conjunction with `mdast-util-from-markdown` to parse a string containing an MDX JSX component into an mdast syntax tree.

"use strict";

var fromMarkdown = require('mdast-util-from-markdown');
var mdxJsx = require('mdast-util-mdx-jsx');

var doc = '<Button>Click me!</Button>';

var tree = fromMarkdown(doc, {
  extensions: [mdxJsx.fromMarkdown()],
});

console.log(tree);

Serializing MDX JSX nodes

This feature enables the serialization of MDX JSX nodes back into a Markdown string with embedded JSX. The code sample shows how to convert an mdast syntax tree containing an MDX JSX element back into a Markdown string using `mdast-util-to-markdown` with the mdx-jsx extension.

"use strict";

var toMarkdown = require('mdast-util-to-markdown');
var mdxJsx = require('mdast-util-mdx-jsx');

var tree = {
  type: 'root',
  children: [
    {
      type: 'mdxJsxFlowElement',
      name: 'Button',
      children: [{type: 'text', value: 'Click me!'}]
    }
  ]
};

var doc = toMarkdown(tree, {
  extensions: [mdxJsx.toMarkdown()],
});

console.log(doc);

Other packages similar to mdast-util-mdx-jsx

remark-mdx

remark-mdx is a plugin for the remark Markdown processor that adds support for parsing and serializing MDX. It is similar to mdast-util-mdx-jsx in that it deals with MDX content, but it operates within the remark ecosystem, providing a higher-level abstraction compared to the lower-level mdast utilities.

rehype-react

rehype-react is a plugin that allows you to transform rehype (HTML AST) trees to React components. While it operates in a different part of the unified ecosystem, focusing on HTML rather than Markdown, it shares the concept of transforming syntax trees (in this case, HTML ASTs) into JSX components, similar to how mdast-util-mdx-jsx works with MDX JSX nodes.

README

mdast-util-mdx-jsx

Extensions to parse and serialize JSX between mdast and markdown.

Contents

• What is this?
• When to use this
• Install
• Use
• API
  • mdxJsxFromMarkdown()
  • mdxJsxToMarkdown(options?)
• Syntax tree
  • Nodes
  • Mixin
  • Content model
• Types
• Compatibility
• Related
• Contribute
• License

What is this?

This package contains extensions that add support for the JSX syntax enabled by MDX to mdast-util-from-markdown and mdast-util-to-markdown.

JSX is an XML-like syntax extension to ECMAScript (JavaScript), which MDX brings to markdown. For more info on MDX, see What is MDX?

When to use this

These tools are all rather low-level. In most cases, you’d want to use remark-mdx with remark instead.

When you are working with syntax trees and want all of MDX, use mdast-util-mdx instead.

When working with mdast-util-from-markdown, you’d want to combine this package with micromark-extension-mdx-jsx.

Install

This package is ESM only. In Node.js (version 12.20+, 14.14+, or 16.0+), install with npm:

npm install mdast-util-mdx-jsx

In Deno with Skypack:

import {mdxJsxFromMarkdown, mdxJsxToMarkdown} from 'https://cdn.skypack.dev/mdast-util-mdx-jsx@1?dts'

In browsers with Skypack:

<script type="module">
  import {mdxJsxFromMarkdown, mdxJsxToMarkdown} from 'https://cdn.skypack.dev/mdast-util-mdx-jsx@1?min'
</script>

Use

Say our document example.mdx contains:

<Box>
  - a list
</Box>

<MyComponent {...props} />

<abbr title="Hypertext Markup Language">HTML</abbr> is a lovely language.

…and our module example.js looks as follows:

import fs from 'node:fs'
import * as acorn from 'acorn'
import {fromMarkdown} from 'mdast-util-from-markdown'
import {toMarkdown} from 'mdast-util-to-markdown'
import {mdxJsx} from 'micromark-extension-mdx-jsx'
import {mdxJsxFromMarkdown, mdxJsxToMarkdown} from 'mdast-util-mdx-jsx'

const doc = fs.readFileSync('example.mdx')

const tree = fromMarkdown(doc, {
  extensions: [mdxJsx({acorn: acorn, addResult: true})],
  mdastExtensions: [mdxJsxFromMarkdown()]
})

console.log(tree)

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

console.log(out)

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

{
  type: 'root',
  children: [
    {
      type: 'mdxJsxFlowElement',
      name: 'Box',
      attributes: [],
      children: [
        {
          type: 'list',
          ordered: false,
          start: null,
          spread: false,
          children: [
            {
              type: 'listItem',
              spread: false,
              checked: null,
              children: [
                {type: 'paragraph', children: [{type: 'text', value: 'a list'}]}
              ]
            }
          ]
        }
      ]
    },
    {
      type: 'mdxJsxFlowElement',
      name: 'MyComponent',
      attributes: [
        {
          type: 'mdxJsxExpressionAttribute',
          value: '...props',
          data: {
            estree: {
              type: 'Program',
              body: [
                {
                  type: 'ExpressionStatement',
                  expression: {
                    type: 'ObjectExpression',
                    properties: [
                      {
                        type: 'SpreadElement',
                        argument: {type: 'Identifier', name: 'props'}
                      }
                    ]
                  }
                }
              ],
              sourceType: 'module'
            }
          }
        }
      ],
      children: []
    },
    {
      type: 'paragraph',
      children: [
        {
          type: 'mdxJsxTextElement',
          name: 'abbr',
          attributes: [
            {
              type: 'mdxJsxAttribute',
              name: 'title',
              value: 'Hypertext Markup Language'
            }
          ],
          children: [{type: 'text', value: 'HTML'}]
        },
        {type: 'text', value: ' is a lovely language.'}
      ]
    }
  ]
}

<Box>
  *   a list
</Box>

<MyComponent {...props} />

<abbr title="Hypertext Markup Language">HTML</abbr> is a lovely language.

API

This package exports the following identifiers: mdxJsxFromMarkdown, mdxJsxToMarkdown. There is no default export.

mdxJsxFromMarkdown()

Function that can be called to get an extension for mdast-util-from-markdown.

When using micromark-extension-mdx-jsx with options.addResult, nodes will have a data.estree field set to an ESTree.

mdxJsxToMarkdown(options?)

Function that can be called to get an extension for mdast-util-to-markdown.

This extension configures mdast-util-to-markdown with options.fences: true and options.resourceLink: true too, do not overwrite them!

options

Configuration (optional).

options.quote

Preferred quote to use around attribute values ('"' or "'", default: '"').

options.quoteSmart

Use the other quote if that results in less bytes (boolean, default: false).

options.tightSelfClosing

Do not use an extra space when closing self-closing elements: <img/> instead of <img /> (boolean, default: false).

options.printWidth

Try and wrap syntax as this width (number, default: Infinity). When set to a finite number (say, 80), the formatter will print attributes on separate lines when a tag doesn’t fit on one line. The normal behavior is to print attributes with spaces between them instead of line endings.

Syntax tree

The following interfaces are added to mdast by this utility.

Nodes

MdxJsxFlowElement

interface MdxJsxFlowElement <: Parent {
  type: "mdxJsxFlowElement"
}

MdxJsxFlowElement includes MdxJsxElement

MdxJsxFlowElement (Parent) represents JSX in flow (block). It can be used where flow content is expected. It includes the mixin MdxJsxElement.

For example, the following markdown:

<w x="y">
  z
</w>

Yields:

{
  type: 'mdxJsxFlowElement',
  name: 'w',
  attributes: [{type: 'mdxJsxAttribute', name: 'x', value: 'y'}],
  children: [{type: 'paragraph', children: [{type: 'text', value: 'z'}]}]
}

MdxJsxTextElement

interface MdxJsxTextElement <: Parent {
  type: "mdxJsxTextElement"
}

MdxJsxTextElement includes MdxJsxElement

MdxJsxTextElement (Parent) represents JSX in text (span, inline). It can be used where phrasing content is expected. It includes the mixin MdxJsxElement.

For example, the following markdown:

a <b c>d</b> e.

Yields:

{
  type: 'mdxJsxTextElement',
  name: 'b',
  attributes: [{type: 'mdxJsxAttribute', name: 'c', value: null}],
  children: [{type: 'text', value: 'd'}]
}

Mixin

MdxJsxElement

interface mixin MdxJsxElement {
  name: string?
  attributes: [MdxJsxExpressionAttribute | MdxJsxAttribute]
}

interface MdxJsxExpressionAttribute <: Literal {
  type: "mdxJsxExpressionAttribute"
}

interface MdxJsxAttribute <: Node {
  type: "mdxJsxAttribute"
  name: string
  value: MdxJsxAttributeValueExpression | string?
}

interface MdxJsxAttributeValueExpression <: Literal {
  type: "mdxJsxAttributeValueExpression"
}

MdxJsxElement represents a JSX element.

The name field can be present and represents an identifier. Without name, the element represents a fragment, in which case no attributes must be present.

The attributes field represents information associated with the node. The value of the attributes field is a list of MdxJsxExpressionAttribute and MdxJsxAttribute nodes.

MdxJsxExpressionAttribute represents an expression (typically in a programming language) that when evaluated results in multiple attributes.

MdxJsxAttribute represents a single attribute. The name field must be present. The value field can be present, in which case it is either a string (a static value) or an expression (typically in a programming language) that when evaluated results in an attribute value.

Content model

FlowContent (MDX JSX)

type MdxJsxFlowContent = MdxJsxFlowElement | FlowContent

PhrasingContent (MDX JSX)

type MdxJsxPhrasingContent = MdxJsxTextElement | PhrasingContent

Types

This package is fully typed with TypeScript. It exports the MdxJsxAttributeValueExpression, MdxJsxAttribute, MdxJsxExpressionAttribute, MdxJsxFlowElement, and MdxJsxTextElement types that represents the supported nodes. It also exports ToMarkdownOptions, which represents the structure of the respective options.

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

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

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

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

visit(tree, (node) => {
  // `node` can now be one of the JSX nodes.
})

Compatibility

Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.

This plugin works with mdast-util-from-markdown version 1+ and mdast-util-to-markdown version 1+.

Related

• micromark/micromark-extension-mdx-jsx — support MDX JSX in micromark
• syntax-tree/mdast-util-mdx — support MDX in mdast
• remarkjs/remark-mdx — support MDX in remark

Contribute

See contributing.md in syntax-tree/.github for ways to get started. See support.md for ways to get help.

This project has a code of conduct. By interacting with this repository, organization, or community you agree to abide by its terms.

License

MIT © Titus Wormer