@haltcase/style ·

Style guide and configurations for tools in the web ecosystem.

• Prettier
• ESLint
• TypeScript

This package originated from Vercel's style guide.

installation

Install @haltcase/style with your preferred package manager:

# npm
npm i --save-dev @haltcase/style

# pnpm
pnpm i --save-dev @haltcase/style

# yarn
yarn add --dev @haltcase/style

[!NOTE] Some scenarios require additional peer dependencies. See the Prettier and ESLint sections.

usage

Prettier

[!NOTE] Prettier is a peer dependency you'll need to install at the root of your project.

See: https://prettier.io/docs/en/install.html

Add the following in package.json:

{
	"prettier": "@haltcase/style/prettier"
}

ESLint

[!NOTE] ESLint is a peer dependency you'll need to install at the root of your project.

See: https://eslint.org/docs/user-guide/getting-started#installation-and-usage

Several ESLint configs are available which can be combined.

Start with at least one of these base configs, which should always be first in extends:

• @haltcase/style/eslint/browser
• @haltcase/style/eslint/node

[!TIP] You can scope configs so they only target specific files.

See: Scoped configuration with overrides.

The following additional configs are available:

• @haltcase/style/eslint/astro (requires eslint-plugin-astro to be installed)
• @haltcase/style/eslint/cjs
• @haltcase/style/eslint/jest
• @haltcase/style/eslint/next (requires @next/eslint-plugin-next to be installed at the same version as next)
• @haltcase/style/eslint/playwright-test
• @haltcase/style/eslint/react
• @haltcase/style/eslint/typescript (requires typescript to be installed and additional configuration)

Be sure to use require.resolve to reference these configs — ESLint requires absolute paths (eslint/eslint#9188).

For example, to use the shared ESLint config(s) in a Next.js project, set the following in .eslintrc.js.

module.exports = {
	extends: [
		require.resolve("@haltcase/style/eslint/browser"),
		require.resolve("@haltcase/style/eslint/react"),
		require.resolve("@haltcase/style/eslint/next")
	]
};

Configuring ESLint for TypeScript

Some of the rules enabled in the TypeScript config require additional type information, so you'll need to use project: true and tsconfigRootDir or explicitly supply the path(s) to your tsconfig.json per the typescript-eslint documentation.

For more information, see: https://typescript-eslint.io/linting/typed-linting/

module.exports = {
	root: true,
	extends: [
		require.resolve("@haltcase/style/eslint/node"),
		require.resolve("@haltcase/style/eslint/typescript")
	],
	parserOptions: {
		project: true,
		tsconfigRootDir: __dirname
	},
	settings: {
		"import/resolver": {
			typescript: {
				project
			}
		}
	}
};

Configuring custom components for jsx-a11y

It's common practice for React apps to have shared components like Button that wrap native elements. You can pass this information along to jsx-a11y via the components setting.

The below list is not exhaustive.

module.exports = {
	root: true,
	extends: [require.resolve("@haltcase/style/eslint/react")],
	settings: {
		"jsx-a11y": {
			components: {
				Article: "article",
				Button: "button",
				Image: "img",
				Input: "input",
				Link: "a",
				Video: "video"
			}
		}
	}
};

Scoped configuration with overrides

ESLint configs can be scoped to include/exclude specific paths. This ensures that rules don't "leak" into places where those rules don't apply.

In this example, Jest rules are only being applied to files matching Jest's default test match pattern.

module.exports = {
	extends: [require.resolve("@haltcase/style/eslint/node")],
	overrides: [
		{
			files: ["**/__tests__/**/*.[jt]s?(x)", "**/?(*.)+(spec|test).[jt]s?(x)"],
			extends: [require.resolve("@haltcase/style/eslint/jest")]
		}
	]
};

A note on file extensions

By default, all TypeScript rules are scoped to files ending with .ts and .tsx.

However, when using overrides, file extensions must be included or ESLint will only include .js files.

module.exports = {
	overrides: [
		{
			files: ["directory/**/*.[jt]s?(x)"],
			rules: {
				"my-rule": "off"
			}
		}
	]
};

TypeScript

Several Typescript configs are available to cover various scenarios:

Typically, you'll only need to extend from one of these:

{
	"extends": "@haltcase/style/typescript/next"
}

You could also combine them with an extends array in Typescript 5+:

{
	"extends": [
		"@haltcase/style/typescript/node",
		"@haltcase/style/typescript/web"
	]
}

[!TIP] Run tsc --showConfig to see the result of the combined configs.

contributing

Please read our contributing guide before creating a pull request.