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Project: micromark/micromark-extension-mdxjs-esm

Package: micromark-extension-mdxjs-esm@0.3.1

  1. Dependencies: 3·Dependents: 1
  2. micromark extension to support MDX JS import/exports
  1. unified 168
  2. markdown 135
  3. mdx 27
  4. javascript 17
  5. micromark 16
  6. micromark-extension 16
  7. mdxjs 8
  8. ecmascript 7
  9. js 5
  10. export 4
  11. es 3
  12. import 2

micromark-extension-mdxjs-esm

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micromark extension to support MDX.js ESM import/exports.

This package provides the low-level modules for integrating with the micromark tokenizer but has no handling of compiling to HTML: go to a syntax tree instead.

You should probably use this with mdast-util-mdxjs-esm (mdast). Or use micromark-extension-mdxjs and mdast-util-mdx instead, which includes both, to support all of MDX.js. Or, use those through remark-mdx (remark).

Install

npm:

npm install micromark-extension-mdxjs-esm

Use

See mdast-util-mdxjs-esm for an example.

API

syntax(options)

Support ESM imports and exports of MDX.

The export of syntax is a function that can be called with options and returns an extension for the micromark parser (to tokenize import/exports; can be passed in extensions).

options
options.acorn

Acorn parser to use (Acorn, required).

options.acornOptions

Options to pass to acorn (Object, default: {ecmaVersion: 2020, locations: true, sourceType: 'module'}). All fields except for locations can be set.

options.addResult

Whether to add an estree field to mdxjsEsm tokens with results from acorn (boolean, default: false).

Syntax

All valid imports and exports are supported, depending on what the given acorn instance and configuration supports.

When the lowercase strings export or import are found, followed by unicode whitespace (\s), we expect JavaScript. Otherwise, like normal in markdown, we exit and it’ll end up as a paragraph. We continue parsing until we find a line ending followed by a blank line. At that point, we parse with acorn: it if parses, we found our block. Otherwise, if parsing failed at the last character, we assume it’s a blank line in code: we continue on until the next blank line and try again. Otherwise, the acorn error is thrown.

import a from "b"
import * as a from "b"
import {a} from "b"
import {a as b} from "c"
import a, {b as c} from "d"
import a, * as b from "c"
import "a"

export var a = ""
export const a = ""
export let a = ""
export var a, b
export var a = "a", b = "b"
export function a() {}
export class a {}
export var {a} = {}
export var {a: b} = {}
export var [a] = []
export default a = 1
export default function a() {}
export default class a {}
export * from "a"
export * as a from "b"
export {a} from "b"
export {a as b} from "c"
export {default} from "b"
export {default as a, b} from "c"

{/* Blank lines are supported in expressions: */}

export function a() {

  return "b"

}

{/* A blank line must be used after import/exports: this is incorrect! */}

import a from "b"
## Hello, world!

Errors

Could not parse import/exports with acorn: $error

This error occurs if acorn crashes (source: micromark-extension-mdxjs-esm, rule id: acorn). For example:

import 1/1

Unexpected $type in code: only import/exports are supported

This error occurs when a non-ESM construct is found (source: micromark-extension-mdxjs-esm, rule id: non-esm). For example:

export var a = 1
var b

Tokens

An mdxjsEsm token is used to reflect the block of import/exports in markdown.

It includes:

Contribute

See contributing.md in micromark/.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