README.md

ESLint Markdown Language Plugin

Lint JS, JSX, TypeScript, and more inside Markdown.

Usage

Installing

Install the plugin alongside ESLint v9 or greater:

npm install --save-dev eslint @eslint/markdown

Configurations

Configuration Name	Description
recommended	Lints all .md files with the recommended rules and assumes CommonMark 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:

// 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	Require languages for fenced code blocks	yes
heading-increment	Enforce heading levels increment by one	yes
no-duplicate-headings	Disallow duplicate headings in the same document	no
no-empty-links	Disallow empty links	yes
no-html	Disallow HTML tags	no
no-invalid-label-refs	Disallow invalid label references	yes
no-missing-label-refs	Disallow missing label references	yes

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 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:

<!-- 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

Language Name	Description
commonmark	Parse using CommonMark Markdown format
gfm	Parse using GitHub-Flavored Markdown format

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

// 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	Extract fenced code blocks from the Markdown code so they can be linted separately.

Editor Integrations

VSCode

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

Atom

The linter-eslint package allows for linting within the Atom IDE.

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

$ 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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