metalint

Metalint

One linter to rule them all.

Metalint is a tool for analyzing all the files in your project. Analysis is delegated to linters (static source code analysis tools):

Language / Technology	Linters
CoffeeScript	CoffeeLint
CSS	Biome, DoIUse, Prettier, PurgeCSS, Stylelint
HTML	HTMLHint, htmllint, markuplint, Prettier
JavaScript	Biome, ESLint, JSHint, JavaScript Standard Style, Prettier
JSON	Ajv, Biome, @mapbox/JSON Lint lines-primitives, @prantlf/JSON Lint, JSON Lint (mod), Prettier
Less	Prettier, Stylelint
Markdown	MarkdownLint
package.json	Depcheck, npm-check-updates, npm-package-json-lint, publint, Sort Package.json
SCSS	Prettier, Stylelint
SugarSS	Stylelint
SVG	Prettier, SVGLint
WebExtension	Add-ons Linter
YAML	YAML Lint, Prettier
	Secretlint

Install

You can install Metalint using npm:

npm install --save-dev metalint

Configuration

All configuration files are grouped together in the .metalint/ directory, which should be placed at the root of the project. The metalint.config.js file exports a JSON object indicating the linters to be used for each file. The other files contain the specific options for the linters.

Example

In this example of configuration files, Metalint analyzes JavaScript (non-minified), HTML and CSS files; with ESLint, HTMLHint and Stylelint linters respectively.

// .metalint/metalint.config.js
export default {
  patterns: ["**", "!/.git/**", "!/node_modules/**"],
  checkers: [
    {
      patterns: ["*.js", "!*.min.js"],
      linters: "eslint",
    },
    {
      patterns: "*.html",
      linters: "htmlhint",
    },
    {
      patterns: "*.css",
      linters: "stylelint",
    },
  ],
};

// .metalint/eslint.config.js
export default {
  rules: {
    quotes: ["error", "double"],
    semi: ["error", "always"],
  },
};

// .metalint/htmlhint.config.js
export default {
  "attr-value-not-empty": false,
};

// .metalint/stylelint.config.js
export default {
  rules: {
    "color-no-invalid-hex": true,
  },
};

If you want to see real configurations, you've got the Metalint configuration itself; or the Cast Kodi configuration (a browser WebExtension developed in JavaScript, HTML, CSS).

Integration

npm

After installing Metalint and the linters in your npm project, you can add the following script to your package.json:

{
  "scripts": {
    "lint": "metalint",
    "lint:fix": "metalint --fix"
  }
}

Metalint can now be used with the following commands: npm run lint and npm run lint:fix.

GitHub Actions

To launch Metalint in your GitHub Actions, you can use the github formatter to report problems in pull requests.

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
        with:
          persist-credentials: false
      - uses: actions/setup-node@395ad3262231945c25e8478fd5baf05154b1d79f # v6.1.0
      - name: Install dependencies
        run: npm ci
      - name: Lint files
        run: npm run lint -- --formatter github