@eslint/markdown

# ESLint Markdown Language Plugin [![npm Version](https://img.shields.io/npm/v/@eslint/markdown.svg)](https://www.npmjs.com/package/@eslint/markdown) [![Downloads](https://img.shields.io/npm/dm/@eslint/markdown.svg)](https://www.npmjs.com/package/@eslint/markdown) [![Build Status](https://github.com/eslint/markdown/workflows/CI/badge.svg)](https://github.com/eslint/markdown/actions) Lint JS, JSX, TypeScript, and more inside Markdown. <img src="screenshot.png" height="142" width="432" alt="A JS code snippet in a Markdown editor has red squiggly underlines. A tooltip explains the problem." /> ## Usage ### Installing Install the plugin alongside ESLint v9 or greater: ```sh npm install --save-dev eslint @eslint/markdown ``` ### Configurations | **Configuration Name** | **Description** | |---------------|-----------------| | `recommended` | Lints all `.md` files with the recommended rules and assumes [CommonMark](https://commonmark.org/) format. | | `processor` | Enables extracting code blocks from all `.md` files so code blocks can be individually linted. | In your `eslint.config.js` file, import `@eslint/markdown` and include the recommended config to enable the Markdown processor on all `.md` files: ```js // eslint.config.js import markdown from "@eslint/markdown"; export default [ ...markdown.configs.recommended // your other configs here ]; ``` ### Rules   | **Rule Name** | **Description** | **Recommended** | | :- | :- | :-: | | [`fenced-code-language`](./docs/rules/fenced-code-language.md) | Require languages for fenced code blocks. | yes | | [`heading-increment`](./docs/rules/heading-increment.md) | Enforce heading levels increment by one. | yes | | [`no-duplicate-headings`](./docs/rules/no-duplicate-headings.md) | Disallow duplicate headings in the same document. | no | | [`no-empty-links`](./docs/rules/no-empty-links.md) | Disallow empty links. | yes | | [`no-html`](./docs/rules/no-html.md) | Disallow HTML tags. | no | | [`no-invalid-label-refs`](./docs/rules/no-invalid-label-refs.md) | Disallow invalid label references. | yes | | [`no-missing-label-refs`](./docs/rules/no-missing-label-refs.md) | Disallow missing label references. | yes |  **Note:** This plugin does not provide formatting rules. We recommend using a source code formatter such as [Prettier](https://prettier.io) for that purpose. In order to individually configure a rule in your `eslint.config.js` file, import `@eslint/markdown` and configure each rule with a prefix: ```js // eslint.config.js import markdown from "@eslint/markdown"; export default [ { files: ["**/*.md"], plugins: { markdown }, language: "markdown/commonmark", rules: { "markdown/no-html": "error" } } ]; ``` You can individually disable rules in Markdown using HTML comments, such as: ```markdown  <custom-element>Hello world!</custom-element>  <another-element>Goodbye world!</another-element>  [Object]  ``` ### Languages | **Language Name** | **Description** | |---------------|-----------------| | `commonmark` | Parse using [CommonMark](https://commonmark.org) Markdown format | | `gfm` | Parse using [GitHub-Flavored Markdown](https://github.github.com/gfm/) format | In order to individually configure a language in your `eslint.config.js` file, import `@eslint/markdown` and configure a `language`: ```js // eslint.config.js import markdown from "@eslint/markdown"; export default [ { files: ["**/*.md"], plugins: { markdown }, language: "markdown/gfm", rules: { "markdown/no-html": "error" } } ]; ``` ### Processors | **Processor Name** | **Description** | |---------------|-----------------| | [`markdown`](./docs/processors/markdown.md) | Extract fenced code blocks from the Markdown code so they can be linted separately. | ## Editor Integrations ### VSCode [`vscode-eslint`](https://github.com/microsoft/vscode-eslint) has built-in support for the Markdown processor. ### Atom The [`linter-eslint`](https://atom.io/packages/linter-eslint) package allows for linting within the [Atom IDE](https://atom.io/). In order to see `@eslint/markdown` work its magic within Markdown code blocks in your Atom editor, you can go to `linter-eslint`'s settings and within "List of scopes to run ESLint on...", add the cursor scope "source.gfm". However, this reports a problem when viewing Markdown which does not have configuration, so you may wish to use the cursor scope "source.embedded.js", but note that `@eslint/markdown` configuration comments and skip directives won't work in this context. ## Contributing ```sh $ git clone https://github.com/eslint/markdown.git $ cd markdown $ npm install $ npm test ``` This project follows the [ESLint contribution guidelines](https://eslint.org/docs/latest/contribute/).   ## Sponsors The following companies, organizations, and individuals support ESLint's ongoing maintenance and development. [Become a Sponsor](https://eslint.org/donate) to get your logo on our READMEs and [website](https://eslint.org/sponsors). <h3>Platinum Sponsors</h3> <p><a href="https://automattic.com"><img src="https://images.opencollective.com/automattic/d0ef3e1/logo.png" alt="Automattic" height="128"></a> <a href="https://www.airbnb.com/"><img src="https://images.opencollective.com/airbnb/d327d66/logo.png" alt="Airbnb" height="128"></a></p><h3>Gold Sponsors</h3> <p><a href="https://trunk.io/"><img src="https://images.opencollective.com/trunkio/fb92d60/avatar.png" alt="trunk.io" height="96"></a></p><h3>Silver Sponsors</h3> <p><a href="https://www.jetbrains.com/"><img src="https://images.opencollective.com/jetbrains/fe76f99/logo.png" alt="JetBrains" height="64"></a> <a href="https://liftoff.io/"><img src="https://images.opencollective.com/liftoff/5c4fa84/logo.png" alt="Liftoff" height="64"></a> <a href="https://americanexpress.io"><img src="https://avatars.githubusercontent.com/u/3853301?v=4" alt="American Express" height="64"></a> <a href="https://www.workleap.com"><img src="https://avatars.githubusercontent.com/u/53535748?u=d1e55d7661d724bf2281c1bfd33cb8f99fe2465f&v=4" alt="Workleap" height="64"></a></p><h3>Bronze Sponsors</h3> <p><a href="https://www.wordhint.net/"><img src="https://images.opencollective.com/wordhint/be86813/avatar.png" alt="WordHint" height="32"></a> <a href="https://www.crosswordsolver.org/anagram-solver/"><img src="https://images.opencollective.com/anagram-solver/2666271/logo.png" alt="Anagram Solver" height="32"></a> <a href="https://icons8.com/"><img src="https://images.opencollective.com/icons8/7fa1641/logo.png" alt="Icons8" height="32"></a> <a href="https://discord.com"><img src="https://images.opencollective.com/discordapp/f9645d9/logo.png" alt="Discord" height="32"></a> <a href="https://www.gitbook.com"><img src="https://avatars.githubusercontent.com/u/7111340?v=4" alt="GitBook" height="32"></a> <a href="https://nx.dev"><img src="https://avatars.githubusercontent.com/u/23692104?v=4" alt="Nx" height="32"></a> <a href="https://herocoders.com"><img src="https://avatars.githubusercontent.com/u/37549774?v=4" alt="HeroCoders" height="32"></a> <a href="https://usenextbase.com"><img src="https://avatars.githubusercontent.com/u/145838380?v=4" alt="Nextbase Starter Kit" height="32"></a></p> <h3>Technology Sponsors</h3> Technology sponsors allow us to use their products and services for free as part of a contribution to the open source ecosystem and our work. <p><a href="https://netlify.com"><img src="https://raw.githubusercontent.com/eslint/eslint.org/main/src/assets/images/techsponsors/netlify-icon.svg" alt="Netlify" height="32"></a> <a href="https://algolia.com"><img src="https://raw.githubusercontent.com/eslint/eslint.org/main/src/assets/images/techsponsors/algolia-icon.svg" alt="Algolia" height="32"></a> <a href="https://1password.com"><img src="https://raw.githubusercontent.com/eslint/eslint.org/main/src/assets/images/techsponsors/1password-icon.svg" alt="1Password" height="32"></a></p>