@mdx-js/mdx
v3.1.0
Published
MDX compiler
Downloads
11,872,638
Readme
@mdx-js/mdx
MDX compiler.
Contents
- What is this?
- When should I use this?
- Install
- Use
- API
- Types
- Architecture
- Compatibility
- Security
- Contribute
- License
What is this?
This package is a compiler that turns MDX into JavaScript. It can also evaluate MDX code.
When should I use this?
This is the core compiler for turning MDX into JavaScript which gives you the most control. If you’re using a bundler (Rollup, esbuild, webpack), a site builder (Next.js), or build system (Vite) which comes with a bundler, you’re better off using an integration: see § Integrations.
Install
This package is ESM only. In Node.js (version 16+), install with npm:
npm install @mdx-js/mdx
In Deno with esm.sh
:
import {compile} from 'https://esm.sh/@mdx-js/mdx@3'
In browsers with esm.sh
:
<script type="module">
import {compile} from 'https://esm.sh/@mdx-js/mdx@3?bundle'
</script>
Use
Say we have an MDX document, example.mdx
:
export function Thing() {
return <>World!</>
}
# Hello, <Thing />
…and some code in example.js
to compile example.mdx
to JavaScript:
import fs from 'node:fs/promises'
import {compile} from '@mdx-js/mdx'
const compiled = await compile(await fs.readFile('example.mdx'))
console.log(String(compiled))
Yields roughly:
import {Fragment as _Fragment, jsx as _jsx, jsxs as _jsxs} from 'react/jsx-runtime'
export function Thing() {
return _jsx(_Fragment, {children: 'World!'})
}
function _createMdxContent(props) {
const _components = {h1: 'h1', ...props.components}
return _jsxs(_components.h1, {children: ['Hello, ', _jsx(Thing, {})]})
}
export default function MDXContent(props = {}) {
const {wrapper: MDXLayout} = props.components || {}
return MDXLayout
? _jsx(MDXLayout, {...props, children: _jsx(_createMdxContent, {...props})})
: _createMdxContent(props)
}
See § Using MDX for more on how MDX work and how to use the result.
API
This package exports the following identifiers:
compile
,
compileSync
,
createProcessor
,
evaluate
,
evaluateSync
,
nodeTypes
,
run
, and
runSync
.
There is no default export.
compile(file, options?)
Compile MDX to JS.
Parameters
file
(Compatible
fromvfile
) — MDX document to parseoptions
(CompileOptions
, optional) — compile configuration
Returns
Promise to compiled file (Promise<VFile>
).
Examples
The input value for file
can be many different things.
You can pass a string
, Uint8Array
in UTF-8, VFile
, or anything
that can be given to new VFile
.
import {compile} from '@mdx-js/mdx'
import {VFile} from 'vfile'
await compile(':)')
await compile(Buffer.from(':-)'))
await compile({path: 'path/to/file.mdx', value: '🥳'})
await compile(new VFile({path: 'path/to/file.mdx', value: '🤭'}))
The output VFile
can be used to access more than the generated code:
import {compile} from '@mdx-js/mdx'
import remarkPresetLintConsistent from 'remark-preset-lint-consistent' // Lint rules to check for consistent markdown.
import {reporter} from 'vfile-reporter'
const file = await compile('*like this* or _like this_?', {remarkPlugins: [remarkPresetLintConsistent]})
console.error(reporter(file))
Yields:
1:16-1:27 warning Emphasis should use `*` as a marker emphasis-marker remark-lint
⚠ 1 warning
compileSync(file, options?)
Synchronously compile MDX to JS.
When possible please use the async compile
.
Parameters
file
(Compatible
fromvfile
) — MDX document to parseoptions
(CompileOptions
, optional) — compile configuration
Returns
Compiled file (VFile
).
createProcessor(options?)
Create a processor to compile markdown or MDX to JavaScript.
Note:
format: 'detect'
is not allowed inProcessorOptions
.
Parameters
options
(ProcessorOptions
, optional) — process configuration
Returns
Processor (Processor
from unified
).
evaluate(file, options)
When you trust your content, evaluate
can work.
When possible, use compile
, write to a file, and then run with
Node or use one of the § Integrations.
☢️ Danger: it’s called evaluate because it
eval
s JavaScript.
Parameters
file
(Compatible
fromvfile
) — MDX document to parseoptions
(EvaluateOptions
, required) — configuration
Returns
Promise to a module (Promise<MDXModule>
from
mdx/types.js
).
The result is an object with a default
field set to the component;
anything else that was exported is available too.
For example, assuming the contents of example.mdx
from § Use was in
file
, then:
import {evaluate} from '@mdx-js/mdx'
import * as runtime from 'react/jsx-runtime'
console.log(await evaluate(file, runtime))
…yields:
{Thing: [Function: Thing], default: [Function: MDXContent]}
Notes
Compiling (and running) MDX takes time.
If you are live-rendering a string of MDX that often changes using a virtual DOM
based framework (such as React), one performance improvement is to call the
MDXContent
component yourself.
The reason is that the evaluate
creates a new function each time, which cannot
be diffed:
const {default: MDXContent} = await evaluate('…')
-<MDXContent {...props} />
+MDXContent(props)
evaluateSync(file, options)
Compile and run MDX, synchronously.
When possible please use the async evaluate
.
☢️ Danger: it’s called evaluate because it
eval
s JavaScript.
Parameters
file
(Compatible
fromvfile
) — MDX document to parseoptions
(EvaluateOptions
, required) — configuration
Returns
Module (MDXModule
from mdx/types.js
).
nodeTypes
List of node types made by mdast-util-mdx
, which have to be passed
through untouched from the mdast tree to the hast tree (Array<string>
).
run(code, options)
Run code compiled with outputFormat: 'function-body'
.
☢️ Danger: this
eval
s JavaScript.
Parameters
code
(VFile
orstring
) — JavaScript function body to runoptions
(RunOptions
, required) — configuration
Returns
Promise to a module (Promise<MDXModule>
from
mdx/types.js
);
the result is an object with a default
field set to the component;
anything else that was exported is available too.
Example
On the server:
import {compile} from '@mdx-js/mdx'
const code = String(await compile('# hi', {outputFormat: 'function-body'}))
// To do: send `code` to the client somehow.
On the client:
import {run} from '@mdx-js/mdx'
import * as runtime from 'react/jsx-runtime'
const code = '' // To do: get `code` from server somehow.
const {default: Content} = await run(code, {...runtime, baseUrl: import.meta.url})
console.log(Content)
…yields:
[Function: MDXContent]
runSync(code, options)
Run code, synchronously.
When possible please use the async run
.
☢️ Danger: this
eval
s JavaScript.
Parameters
code
(VFile
orstring
) — JavaScript function body to runoptions
(RunOptions
, required) — configuration
Returns
Module (MDXModule
from mdx/types.js
).
CompileOptions
Configuration for compile
(TypeScript type).
CompileOptions
is the same as ProcessorOptions
with the exception that the format
option supports a 'detect'
value,
which is the default.
The 'detect'
format means to use 'md'
for files with an extension in
mdExtensions
and 'mdx'
otherwise.
Type
/**
* Configuration for `compile`
*/
type CompileOptions = Omit<ProcessorOptions, 'format'> & {
/**
* Format of `file` (default: `'detect'`).
*/
format?: 'detect' | 'md' | 'mdx' | null | undefined
}
EvaluateOptions
Configuration for evaluate
(TypeScript type).
EvaluateOptions
is the same as CompileOptions
,
except that the options baseUrl
, jsx
, jsxImportSource
, jsxRuntime
,
outputFormat
, pragma
, pragmaFrag
, pragmaImportSource
, and
providerImportSource
are not allowed, and that
RunOptions
are also used.
Type
/**
* Configuration for `evaluate`.
*/
type EvaluateOptions = Omit<
CompileOptions,
| 'baseUrl' // Note that this is also in `RunOptions`.
| 'jsx'
| 'jsxImportSource'
| 'jsxRuntime'
| 'outputFormat'
| 'pragma'
| 'pragmaFrag'
| 'pragmaImportSource'
| 'providerImportSource'
> &
RunOptions
Fragment
Represent the children, typically a symbol (TypeScript type).
Type
type Fragment = unknown
Jsx
Create a production element (TypeScript type).
Parameters
type
(unknown
) — element type:Fragment
symbol, tag name (string
), componentproperties
(Properties
) — element properties andchildren
key
(string
orundefined
) — key to use
Returns
Element from your framework (JSX.Element
).
JsxDev
Create a development element (TypeScript type).
Parameters
type
(unknown
) — element type:Fragment
symbol, tag name (string
), componentproperties
(Properties
) — element properties andchildren
key
(string
orundefined
) — key to useisStaticChildren
(boolean
) — whether two or more children are passed (in an array), which is whetherjsxs
orjsx
would be usedsource
(Source
) — info about sourceself
(unknown
) — context object (this
)
ProcessorOptions
Configuration for createProcessor
(TypeScript type).
Fields
SourceMapGenerator
(SourceMapGenerator
fromsource-map
, optional) — add a source map (object form) as themap
field on the resulting fileAssuming
example.mdx
from § Use exists, then:import fs from 'node:fs/promises' import {compile} from '@mdx-js/mdx' import {SourceMapGenerator} from 'source-map' const file = await compile( {path: 'example.mdx', value: await fs.readFile('example.mdx')}, {SourceMapGenerator} ) console.log(file.map)
…yields:
{ file: 'example.mdx', mappings: ';;aAAaA,QAAQ;YAAQ;;;;;;;;iBAE3B', names: ['Thing'], sources: ['example.mdx'], version: 3 }
baseUrl
(URL
orstring
, optional, example:import.meta.url
) — use this URL asimport.meta.url
and resolveimport
andexport … from
relative to itSay we have a module
example.js
:import {compile} from '@mdx-js/mdx' const code = 'export {number} from "./data.js"\n\n# hi' const baseUrl = 'https://a.full/url' // Typically `import.meta.url` console.log(String(await compile(code, {baseUrl})))
…now running
node example.js
yields:import {jsx as _jsx} from 'react/jsx-runtime' export {number} from 'https://a.full/data.js' function _createMdxContent(props) { /* … */ } export default function MDXContent(props = {}) { /* … */ }
development
(boolean
, default:false
) — whether to add extra info to error messages in generated code and use the development automatic JSX runtime (Fragment
andjsxDEV
from/jsx-dev-runtime
); when using the webpack loader (@mdx-js/loader
) or the Rollup integration (@mdx-js/rollup
) through Vite, this is automatically inferred from how you configure those toolsSay we had some MDX that references a component that can be passed or provided at runtime:
**Note**<NoteIcon />: some stuff.
And a module to evaluate that:
import fs from 'node:fs/promises' import {evaluate} from '@mdx-js/mdx' import * as runtime from 'react/jsx-runtime' const path = 'example.mdx' const value = await fs.readFile(path) const MDXContent = (await evaluate({path, value}, {...runtime, baseUrl: import.meta.url})).default console.log(MDXContent({}))
…running that would normally (production) yield:
Error: Expected component `NoteIcon` to be defined: you likely forgot to import, pass, or provide it. at _missingMdxReference (eval at run (…/@mdx-js/mdx/lib/run.js:18:10), <anonymous>:27:9) at _createMdxContent (eval at run (…/@mdx-js/mdx/lib/run.js:18:10), <anonymous>:15:20) at MDXContent (eval at run (…/@mdx-js/mdx/lib/run.js:18:10), <anonymous>:9:9) at main (…/example.js:11:15)
…but if we add
development: true
to our example:@@ -7,6 +7,6 @@ import fs from 'node:fs/promises' -import * as runtime from 'react/jsx-runtime' +import * as runtime from 'react/jsx-dev-runtime' import {evaluate} from '@mdx-js/mdx' const path = 'example.mdx' const value = await fs.readFile(path) -const MDXContent = (await evaluate({path, value}, {...runtime, baseUrl: import.meta.url})).default +const MDXContent = (await evaluate({path, value}, {development: true, ...runtime, baseUrl: import.meta.url})).default console.log(MDXContent({}))
…and we’d run it again, we’d get:
Error: Expected component `NoteIcon` to be defined: you likely forgot to import, pass, or provide it. It’s referenced in your code at `1:9-1:21` in `example.mdx` provide it. at _missingMdxReference (eval at run (…/@mdx-js/mdx/lib/run.js:18:10), <anonymous>:27:9) at _createMdxContent (eval at run (…/@mdx-js/mdx/lib/run.js:18:10), <anonymous>:15:20) at MDXContent (eval at run (…/@mdx-js/mdx/lib/run.js:18:10), <anonymous>:9:9) at main (…/example.js:11:15)
elementAttributeNameCase
('html'
or'react
, default:'react'
) — casing to use for attribute names; HTML casing is for exampleclass
,stroke-linecap
,xml:lang
; React casing is for exampleclassName
,strokeLinecap
,xmlLang
; for JSX components written in MDX, the author has to be aware of which framework they use and write code accordingly; for AST nodes generated by this project, this option configures itformat
('md'
or'mdx'
, default:'mdx'
) — format of the file;'md'
means treat as markdown and'mdx'
means treat as MDXcompile('…') // Seen as MDX. compile('…', {format: 'mdx'}) // Seen as MDX. compile('…', {format: 'md'}) // Seen as markdown.
jsx
(boolean
, default:false
) — whether to keep JSX; the default is to compile JSX away so that the resulting file is immediately runnable.If
file
is the contents ofexample.mdx
from § Use, then:compile(file, {jsx: true})
…yields this difference:
-import {Fragment as _Fragment, jsx as _jsx, jsxs as _jsxs} from 'react/jsx-runtime' +/*@jsxRuntime automatic*/ +/*@jsxImportSource react*/ export function Thing() { - return _jsx(_Fragment, {children: 'World'}) + return <>World!</> } function _createMdxContent(props) { const _components = { h1: 'h1', ...props.components } - return _jsxs(_components.h1, {children: ['Hello ', _jsx(Thing, {})]}) + return <_components.h1>{"Hello "}<Thing /></_components.h1> } export default function MDXContent(props = {}) { const {wrapper: MDXLayout} = props.components || {} return MDXLayout - ? _jsx(MDXLayout, { - ...props, - children: _jsx(_createMdxContent, props) - }) + ? <MDXLayout {...props}><_createMdxContent {...props} /></MDXLayout> : _createMdxContent(props) } }
jsxImportSource
(string
, default:'react'
) — place to import automatic JSX runtimes from; when in theautomatic
runtime, this is used to define an import forFragment
,jsx
,jsxDEV
, andjsxs
If
file
is the contents ofexample.mdx
from § Use, then:compile(file, {jsxImportSource: 'preact'})
…yields this difference:
-import {Fragment as _Fragment, jsx as _jsx, jsxs as _jsxs} from 'react/jsx-runtime' +import {Fragment as _Fragment, jsx as _jsx, jsxs as _jsxs } from 'preact/jsx-runtime'
jsxRuntime
('automatic'
or'classic'
, default:'automatic'
) — JSX runtime to use; the automatic runtime compiles toimport _jsx from '$importSource/jsx-runtime'\n_jsx('p')
; the classic runtime compiles to calls such ash('p')
👉 Note: support for the classic runtime is deprecated and will likely be removed in the next major version.
If
file
is the contents ofexample.mdx
from § Use, then:compile(file, {jsxRuntime: 'classic'})
…yields this difference:
-import {Fragment as _Fragment, jsx as _jsx, jsxs as _jsxs} from 'react/jsx-runtime' +import React from 'react' export function Thing() { - return _jsx(_Fragment, {children: 'World'}) + return React.createElement(React.Fragment, null, 'World!') } …
outputFormat
('function-body'
or'program'
, default:'program'
) — output format to generate; in most cases'program'
should be used, it results in a whole program; internallyevaluate
uses'function-body'
to compile to code that can be passed torun
; in some cases, you might want whatevaluate
does in separate steps, such as when compiling on the server and running on the client.With a module
example.js
:import {compile} from '@mdx-js/mdx' const code = 'export const no = 3.14\n\n# hi {no}' console.log(String(await compile(code, {outputFormat: 'program'}))) // Default. console.log(String(await compile(code, {outputFormat: 'function-body'})))
…yields:
import {jsx as _jsx, jsxs as _jsxs} from 'react/jsx-runtime' export const no = 3.14 function _createMdxContent(props) { /* … */ } export default function MDXContent(props = {}) { /* … */ }
'use strict' const {Fragment: _Fragment, jsx: _jsx} = arguments[0] const no = 3.14 function _createMdxContent(props) { /* … */ } function MDXContent(props = {}) { /* … */ } return {no, default: MDXContent}
The
'program'
format will use import statements to import the runtime (and optionally provider) and use an export statement to yield theMDXContent
component.The
'function-body'
format will get the runtime (and optionally provider) fromarguments[0]
, rewrite export statements, and use a return statement to yield what was exported.mdExtensions
(Array<string>
, default:['.md', '.markdown', '.mdown', '.mkdn', '.mkd', '.mdwn', '.mkdown', '.ron']
) — list of markdown extensions, with dot affects § IntegrationsmdxExtensions
(Array<string>
, default:['.mdx']
) — list of MDX extensions, with dot; affects § Integrationspragma
(string
, default:'React.createElement'
) — pragma for JSX, used in the classic runtime as an identifier for function calls:<x />
toReact.createElement('x')
; when changing this, you should also definepragmaFrag
andpragmaImportSource
too👉 Note: support for the classic runtime is deprecated and will likely be removed in the next major version.
If
file
is the contents ofexample.mdx
from § Use, then:compile(file, { jsxRuntime: 'classic', pragma: 'preact.createElement', pragmaFrag: 'preact.Fragment', pragmaImportSource: 'preact/compat' })
…yields this difference:
-import React from 'react' +import preact from 'preact/compat' export function Thing() { - return React.createElement(React.Fragment, null, 'World!') + return preact.createElement(preact.Fragment, null, 'World!') } …
pragmaFrag
(string
, default:'React.Fragment'
) — pragma for fragment symbol, used in the classic runtime as an identifier for unnamed calls:<>
toReact.createElement(React.Fragment)
; when changing this, you should also definepragma
andpragmaImportSource
too👉 Note: support for the classic runtime is deprecated and will likely be removed in the next major version.
pragmaImportSource
(string
, default:'react'
) — where to import the identifier ofpragma
from, used in the classic runtime; to illustrate, whenpragma
is'a.b'
andpragmaImportSource
is'c'
the following will be generated:import a from 'c'
and things such asa.b('h1', {})
; when changing this, you should also definepragma
andpragmaFrag
too👉 Note: support for the classic runtime is deprecated and will likely be removed in the next major version.
providerImportSource
(string
, optional, example:'@mdx-js/react'
) — place to import a provider from; normally it’s used for runtimes that support context (React, Preact), but it can be used to inject components into the compiled code; the module must export and identifieruseMDXComponents
which is called without arguments to get an object of components (seeUseMdxComponents
)If
file
is the contents ofexample.mdx
from § Use, then:compile(file, {providerImportSource: '@mdx-js/react'})
…yields this difference:
import {Fragment as _Fragment, jsx as _jsx, jsxs as _jsxs} from 'react/jsx-runtime' +import {useMDXComponents as _provideComponents} from '@mdx-js/react' export function Thing() { return _jsx(_Fragment, {children: 'World'}) } function _createMdxContent(props) { const _components = { h1: 'h1', + ..._provideComponents(), ...props.components } return _jsxs(_components.h1, {children: ['Hello ', _jsx(Thing, {})]}) } export default function MDXContent(props = {}) { - const {wrapper: MDXLayout} = props.components || {} + const {wrapper: MDXLayout} = { + ..._provideComponents(), + ...props.components + } return MDXLayout ? _jsx(MDXLayout, {...props, children: _jsx(_createMdxContent, {})}) : _createMdxContent()
recmaPlugins
(PluggableList
fromunified
, optional) — list of recma plugins; this is a new ecosystem, currently in beta, to transform esast trees (JavaScript)import recmaMdxIsMdxComponent from 'recma-mdx-is-mdx-component' await compile(file, {recmaPlugins: [recmaMdxIsMdxComponent]})
rehypePlugins
(PluggableList
fromunified
, optional) — list of rehype pluginsimport rehypeKatex from 'rehype-katex' // Render math with KaTeX. import remarkMath from 'remark-math' // Support math like `$so$`. await compile(file, {rehypePlugins: [rehypeKatex], remarkPlugins: [remarkMath]}) await compile(file, { // A plugin with options: rehypePlugins: [[rehypeKatex, {strict: true, throwOnError: true}]], remarkPlugins: [remarkMath] })
remarkPlugins
(PluggableList
fromunified
, optional) — list of remark pluginsimport remarkFrontmatter from 'remark-frontmatter' // YAML and such. import remarkGfm from 'remark-gfm' // Tables, footnotes, strikethrough, task lists, literal URLs. await compile(file, {remarkPlugins: [remarkGfm]}) // One plugin. await compile(file, {remarkPlugins: [[remarkFrontmatter, 'toml']]}) // A plugin with options. await compile(file, {remarkPlugins: [remarkGfm, remarkFrontmatter]}) // Two plugins. await compile(file, {remarkPlugins: [[remarkGfm, {singleTilde: false}], remarkFrontmatter]}) // Two plugins, first w/ options.
remarkRehypeOptions
(Options
fromremark-rehype
, optional) — options to pass through toremark-rehype
; the optionallowDangerousHtml
will always be set totrue
and the MDX nodes (seenodeTypes
) are passed through; In particular, you might want to pass configuration for footnotes if your content is not in Englishcompile({value: '…'}, {remarkRehypeOptions: {clobberPrefix: 'comment-1'}})
stylePropertyNameCase
('css'
or'dom
, default:'dom'
) — casing to use for property names instyle
objects; CSS casing is for examplebackground-color
and-webkit-line-clamp
; DOM casing is for examplebackgroundColor
andWebkitLineClamp
; for JSX components written in MDX, the author has to be aware of which framework they use and write code accordingly; for AST nodes generated by this project, this option configures ittableCellAlignToStyle
(boolean
, default:true
) — turn obsoletealign
properties ontd
andth
into CSSstyle
properties
RunOptions
Configuration to run compiled code (TypeScript type).
Fragment
, jsx
, and jsxs
are used when the code is compiled in production
mode (development: false
).
Fragment
and jsxDEV
are used when compiled in development mode
(development: true
).
useMDXComponents
is used when the code is compiled with
providerImportSource: '#'
(the exact value of this compile option doesn’t
matter).
Fields
Fragment
(Fragment
, required) — symbol to use for fragmentsbaseUrl
(URL
orstring
, optional, example:import.meta.url
) — use this URL asimport.meta.url
and resolveimport
andexport … from
relative to it; this option can also be given at compile time inCompileOptions
; you should pass this (likely at runtime), as you might get runtime errors when usingimport.meta.url
/import
/export … from
otherwisejsx
(Jsx
, optional) — function to generate an element with static children in production modejsxDEV
(JsxDev
, optional) — function to generate an element in development modejsxs
(Jsx
, optional) — function to generate an element with dynamic children in production modeuseMDXComponents
(UseMdxComponents
, optional) — function to get components to use
Examples
A /jsx-runtime
module will expose Fragment
, jsx
, and jsxs
:
import * as runtime from 'react/jsx-runtime'
const {default: Content} = await evaluate('# hi', {...runtime, baseUrl: import.meta.url, ...otherOptions})
A /jsx-dev-runtime
module will expose Fragment
and jsxDEV
:
import * as runtime from 'react/jsx-dev-runtime'
const {default: Content} = await evaluate('# hi', {development: true, baseUrl: import.meta.url, ...runtime, ...otherOptions})
Our providers will expose useMDXComponents
:
import * as provider from '@mdx-js/react'
import * as runtime from 'react/jsx-runtime'
const {default: Content} = await evaluate('# hi', {...provider, ...runtime, baseUrl: import.meta.url, ...otherOptions})
UseMdxComponents
Get components (TypeScript type).
Parameters
There are no parameters.
Returns
Components (MDXComponents
from mdx/types.js
).
Types
This package is fully typed with TypeScript.
It exports the additional types
CompileOptions
,
EvaluateOptions
,
Fragment
,
Jsx
,
JsxDev
,
ProcessorOptions
,
RunOptions
, and
UseMdxComponents
.
For types of evaluated MDX to work, make sure the TypeScript JSX
namespace is
typed.
This is done by installing and using the types of your framework, such as
@types/react
.
See § Types on our website for information.
Architecture
To understand what this project does, it’s very important to first understand
what unified does: please read through the unifiedjs/unified
readme
(the part until you hit the API section is required reading).
@mdx-js/mdx
is a unified pipeline — wrapped so that most folks don’t need to
know about unified.
The processor goes through these steps:
- parse MDX (serialized markdown with embedded JSX, ESM, and expressions) to mdast (markdown syntax tree)
- transform through remark (markdown ecosystem)
- transform mdast to hast (HTML syntax tree)
- transform through rehype (HTML ecosystem)
- transform hast to esast (JS syntax tree)
- do the work needed to get a component
- transform through recma (JS ecosystem)
- serialize esast as JavaScript
The input is MDX (serialized markdown with embedded JSX, ESM, and
expressions).
The markdown is parsed with micromark/micromark
and the embedded
JS with one of its extensions
micromark/micromark-extension-mdxjs
(which in
turn uses acorn).
Then syntax-tree/mdast-util-from-markdown
and its
extension syntax-tree/mdast-util-mdx
are used to turn the
results from the parser into a syntax tree: mdast.
Markdown is closest to the source format.
This is where remark plugins come in.
Typically, there shouldn’t be much going on here.
But perhaps you want to support GFM (tables and such) or frontmatter?
Then you can add a plugin here: remark-gfm
or remark-frontmatter
,
respectively.
After markdown, we go to hast (HTML).
This transformation is done by
syntax-tree/mdast-util-to-hast
.
Wait, why, what is HTML needed?
Part of the reason is that we care about HTML semantics: we want to know that
something is an <a>
, not whether it’s a link with a resource ([text](url)
)
or a reference to a defined link definition ([text][id]\n\n[id]: url
).
So an HTML AST is closer to where we want to go.
Another reason is that there are many things folks need when they go MDX -> JS,
markdown -> HTML, or even folks who only process their HTML -> HTML: use cases
other than MDX.
By having a single AST in these cases and writing a plugin that works on that
AST, that plugin can supports all these use cases (for example,
rehypejs/rehype-highlight
for syntax highlighting or
rehypejs/rehype-katex
for math).
So, this is where rehype plugins come in: most of the plugins,
probably.
Then we go to JavaScript: esast (JS; an
AST which is compatible with estree but looks a bit more like other unist ASTs).
This transformation is done by
rehype-recma
.
This is a new ecosystem that does not have utilities or plugins yet.
But it’s where @mdx-js/mdx
does its thing: where it adds imports/exports,
where it compiles JSX away into _jsx()
calls, and where it does the other cool
things that it provides.
Finally, The output is serialized JavaScript. That final step is done by astring, a small and fast JS generator.
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, @mdx-js/mdx@^3
,
compatible with Node.js 16.
Security
See § Security on our website for information.
Contribute
See § Contribute on our website for ways to get started. See § Support for ways to get help.
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