eslint
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/markdownConfigurations
| 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"
}
}
];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/markdowninternally usesmicromark-extension-frontmatterandmdast-util-frontmatterto parse front matter.
| Option Value | Description |
|---|---|
false |
Disables front matter parsing in Markdown files. (Default) |
"yaml" |
Enables YAML front matter parsing in Markdown files. |
"toml" |
Enables TOML front matter parsing in Markdown files. |
// eslint.config.js
import markdown from "@eslint/markdown";
export default [
{
files: ["**/*.md"],
plugins: {
markdown
},
language: "markdown/gfm",
languageOptions: {
frontmatter: "yaml", // Or pass `"toml"` to enable TOML front matter parsing.
},
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.
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 testThis project follows the ESLint contribution guidelines.
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