eslint/markdown

ESLint Markdown Language Plugin

Lint Markdown with ESLint, as well JS, JSX, TypeScript, and more inside Markdown.

Usage

Installing

Install the plugin alongside ESLint v9.15.0 or greater. Type compatibility is guaranteed with ESLint v9.39.0 or greater.

You can install ESLint using npm or other package managers:

npm install eslint -D
# or
yarn add eslint -D
# or
pnpm install eslint -D
# or
bun add eslint -D

Then, for Node.js and compatible runtimes:

npm install @eslint/markdown -D
# or
yarn add @eslint/markdown -D
# or
pnpm install @eslint/markdown -D
# or
bun add @eslint/markdown -D

For Deno:

deno add jsr:@eslint/markdown

Configurations

In your eslint.config.js file, import @eslint/markdown and include the recommended config to enable Markdown parsing and linting:

// eslint.config.js
import { defineConfig } from "eslint/config";
import markdown from "@eslint/markdown";

export default defineConfig([
	{
		files: ["**/*.md"],
		plugins: {
			markdown,
		},
		extends: ["markdown/recommended"],
	},
	// your other configs here
]);

You can also modify the recommended config by using extends:

// eslint.config.js
import { defineConfig } from "eslint/config";
import markdown from "@eslint/markdown";

export default defineConfig([
	{
		plugins: {
			markdown,
		},
		extends: ["markdown/recommended"],
		rules: {
			"markdown/no-html": "error",
		},
	},

	// your other configs here
]);

Rules

Note: This plugin does not provide formatting rules. We recommend using a source code formatter such as Prettier 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:

// eslint.config.js
import { defineConfig } from "eslint/config";
import markdown from "@eslint/markdown";

export default defineConfig([
	{
		files: ["**/*.md"],
		plugins: {
			markdown,
		},
		language: "markdown/commonmark",
		rules: {
			"markdown/no-html": "error",
		},
	},
]);

You can individually disable rules in Markdown using HTML comments, such as:

<!-- eslint-disable-next-line markdown/no-html -- I want to allow HTML here -->
<custom-element>Hello world!</custom-element>

<!-- eslint-disable markdown/no-html -- here too -->
<another-element>Goodbye world!</another-element>
<!-- eslint-enable markdown/no-html -- safe to re-enable now -->

[Object] <!-- eslint-disable-line markdown/no-missing-label-refs -- not meant to be a link ref -->

Languages

In order to individually configure a language in your eslint.config.js file, import @eslint/markdown and configure a language:

// eslint.config.js
import { defineConfig } from "eslint/config";
import markdown from "@eslint/markdown";

export default defineConfig([
	{
		files: ["**/*.md"],
		plugins: {
			markdown,
		},
		language: "markdown/gfm",
		rules: {
			"markdown/no-html": "error",
		},
	},
]);

Language Options

Enabling Front Matter in both commonmark and gfm

By default, Markdown parsers do not support front matter. To enable front matter in both commonmark and gfm, you can use the frontmatter option in languageOptions.

@eslint/markdown internally uses micromark-extension-frontmatter and mdast-util-frontmatter to parse front matter.

// eslint.config.js
import { defineConfig } from "eslint/config";
import markdown from "@eslint/markdown";

export default defineConfig([
	{
		files: ["**/*.md"],
		plugins: {
			markdown,
		},
		language: "markdown/gfm",
		languageOptions: {
			frontmatter: "yaml", // Or pass `"toml"` or `"json"` to enable TOML or JSON front matter parsing.
		},
		rules: {
			"markdown/no-html": "error",
		},
	},
]);

Enabling Math (LaTeX) in both commonmark and gfm

By default, Markdown parsers do not support math (LaTeX). To enable math in both commonmark and gfm, you can use the math option in languageOptions.

@eslint/markdown internally uses micromark-extension-math and mdast-util-math to parse math.

// eslint.config.js
import { defineConfig } from "eslint/config";
import markdown from "@eslint/markdown";

export default defineConfig([
	{
		files: ["**/*.md"],
		plugins: {
			markdown,
		},
		language: "markdown/gfm",
		languageOptions: {
			math: true, // Or pass `false` to disable math parsing.
		},
		rules: {
			"markdown/no-html": "error",
		},
	},
]);

Processors

Important: You cannot lint a file's Markdown content and its fenced code blocks in a single ESLint run. When the markdown processor is applied, only the extracted code blocks are linted. This is a current limitation of ESLint processors. See Linting Markdown Content and Code Blocks for a way to lint both.

Migration from eslint-plugin-markdown

See Migration.

Editor Integrations

VSCode

vscode-eslint has built-in support for the Markdown processor.

File Name Details

This processor will use file names from blocks if a filename meta is present.

For example, the following block will result in a parsed file name of src/index.js:

```js filename="src/index.js"
export const value = "Hello, world!";
```

This can be useful for user configurations that include linting overrides for specific file paths. In this example, you could then target the specific code block in your configuration using "file-name.md/*src/index.js".

Contributing

$ git clone https://github.com/eslint/markdown.git
$ cd markdown
$ npm install
$ npm test

This project follows the ESLint contribution guidelines.

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