npm package: @kmblabs/config
Description: KMB Labs' ESLint config
Author: KMB Labs
Latest version: 1.0.2

# @kmblabs/config

## Usage

### Install

```bash
yarn add -D eslint @kmblabs/config
```

### Create config file

With [`"type": "module"`](https://nodejs.org/api/packages.html#type) in `package.json` (recommended):

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint();
```

With CJS:

```js
// eslint.config.js
const eslint = require("@kmblabs/config").default;

module.exports = eslint();
```

> [!TIP]
> ESLint only detects `eslint.config.js` as the flat config entry, meaning you need to put `type: module` in your `package.json` or you have to use CJS in `eslint.config.js`. If you want explicit extension like `.mjs` or `.cjs`, or even `eslint.config.ts`, you can install [`eslint-ts-patch`](https://github.com/antfu/eslint-ts-patch) to fix it.

Combined with legacy config:

```js
// eslint.config.js
const eslint = require("@kmblabs/config").default;
const { FlatCompat } = require("@eslint/eslintrc");

const compat = new FlatCompat();

module.exports = eslint(
  {
    ignores: [],
  },

  // Legacy config
  ...compat.config({
    extends: [
      "eslint:recommended",
      // Other extends...
    ],
  })

  // Other flat configs...
);
```

> Note that `.eslintignore` no longer works in Flat config, see [customization](#customization) for more details.

### Add script for package.json

For example:

```json
{
  "scripts": {
    "lint": "eslint .",
    "lint:fix": "eslint . --fix"
  }
}
```

### Migration

We provided an experimental CLI tool to help you migrate from the legacy config to the new flat config.

```bash
npx @kmblabs/config@latest
```

Before running the migration, make sure to commit your unsaved changes first.

## VS Code support (auto fix)

Install [VS Code ESLint extension](https://marketplace.visualstudio.com/items?itemName=dbaeumer.vscode-eslint)

Add the following settings to your `.vscode/settings.json`:

```jsonc
{
  // Enable the ESlint flat config support
  "eslint.experimental.useFlatConfig": true,

  // Disable the default formatter, use eslint instead
  "prettier.enable": false,
  "editor.formatOnSave": false,

  // Auto fix
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": "explicit",
    "source.organizeImports": "never"
  },

  // Silent the stylistic rules in you IDE, but still auto fix them
  "eslint.rules.customizations": [
    { "rule": "style/*", "severity": "off" },
    { "rule": "format/*", "severity": "off" },
    { "rule": "*-indent", "severity": "off" },
    { "rule": "*-spacing", "severity": "off" },
    { "rule": "*-spaces", "severity": "off" },
    { "rule": "*-order", "severity": "off" },
    { "rule": "*-dangle", "severity": "off" },
    { "rule": "*-newline", "severity": "off" },
    { "rule": "*quotes", "severity": "off" },
    { "rule": "*semi", "severity": "off" }
  ],

  // Enable eslint for all supported languages
  "eslint.validate": [
    "javascript",
    "javascriptreact",
    "typescript",
    "typescriptreact",
    "vue",
    "html",
    "markdown",
    "json",
    "jsonc",
    "yaml",
    "toml"
  ]
}
```

## Customization

Since v1.0, we migrated to [ESLint Flat config](https://eslint.org/docs/latest/use/configure/configuration-files-new). It provides much better organization and composition.

Normally you only need to import the `eslint` preset:

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint();
```

And that's it! Or you can configure each integration individually, for example:

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint({
  // Enable stylistic formatting rules
  // stylistic: true,

  // Or customize the stylistic rules
  stylistic: {
    indent: 2, // 4, or 'tab'
    quotes: "single", // or 'double'
  },

  // TypeScript and Vue are auto-detected, you can also explicitly enable them:
  typescript: true,
  vue: true,

  // Disable jsonc and yaml support
  jsonc: false,
  yaml: false,

  // `.eslintignore` is no longer supported in Flat config, use `ignores` instead
  ignores: [
    "**/fixtures",
    // ...globs
  ]
});
```

The `eslint` factory function also accepts any number of arbitrary custom config overrides:

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint(
  {
    // Configures for eslint's config
  },

  // From the second arguments they are ESLint Flat Configs
  // you can have multiple configs
  {
    files: [ "**/*.ts" ],
    rules: {},
  },
  {
    rules: {},
  },
);
```

Going more advanced, you can also import fine-grained configs and compose them as you wish:

<details>
<summary>Advanced Example</summary>

We wouldn't recommend using this style in general unless you know exactly what they are doing, as there are shared options between configs and might need extra care to make them consistent.

```js
// eslint.config.js
import {
  combine,
  comments,
  ignores,
  imports,
  javascript,
  jsdoc,
  jsonc,
  markdown,
  node,
  sortPackageJson,
  sortTsconfig,
  stylistic,
  toml,
  typescript,
  unicorn,
  vue,
  yaml,
} from "@kmblabs/config";

export default combine(
  ignores(),
  javascript(/* Options */),
  comments(),
  node(),
  jsdoc(),
  imports(),
  unicorn(),
  typescript(/* Options */),
  stylistic(),
  vue(),
  jsonc(),
  yaml(),
  toml(),
  markdown(),
);
```

</details>

Check out the [configs](https://github.com/antfu/eslint-config/blob/main/src/configs) and [factory](https://github.com/antfu/eslint-config/blob/main/src/factory.ts) for more details.

> Thanks to [sxzz/eslint-config](https://github.com/sxzz/eslint-config) for the inspiration and reference.

### Plugins Renaming

Since flat config requires us to explicitly provide the plugin names (instead of the mandatory convention from npm package name), we renamed some plugins to make the overall scope more consistent and easier to write.

| New Prefix | Original Prefix        | Source Plugin                                                                              |
| ---------- | ---------------------- | ------------------------------------------------------------------------------------------ |
| `import/*` | `i/*`                  | [eslint-plugin-i](https://github.com/un-es/eslint-plugin-i)                                |
| `node/*`   | `n/*`                  | [eslint-plugin-n](https://github.com/eslint-community/eslint-plugin-n)                     |
| `yaml/*`   | `yml/*`                | [eslint-plugin-yml](https://github.com/ota-meshi/eslint-plugin-yml)                        |
| `ts/*`     | `@typescript-eslint/*` | [@typescript-eslint/eslint-plugin](https://github.com/typescript-eslint/typescript-eslint) |
| `style/*`  | `@stylistic/*`         | [@stylistic/eslint-plugin](https://github.com/eslint-stylistic/eslint-stylistic)           |
| `test/*`   | `vitest/*`             | [eslint-plugin-vitest](https://github.com/veritem/eslint-plugin-vitest)                    |
| `test/*`   | `no-only-tests/*`      | [eslint-plugin-no-only-tests](https://github.com/levibuzolic/eslint-plugin-no-only-tests)  |

When you want to override rules, or disable them inline, you need to update to the new prefix:

```diff
-// eslint-disable-next-line @typescript-eslint/consistent-type-definitions
+// eslint-disable-next-line ts/consistent-type-definitions
type foo = { bar: 2 }
```

### Rules Overrides

Certain rules would only be enabled in specific files, for example, `ts/*` rules would only be enabled in `.ts` files and `vue/*` rules would only be enabled in `.vue` files. If you want to override the rules, you need to specify the file extension:

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint(
  {
    vue: true,
    typescript: true
  },
  {
    // Remember to specify the file glob here, otherwise it might cause the vue plugin to handle non-vue files
    files: [ "**/*.vue" ],
    rules: {
      "vue/operator-linebreak": [ "error", "before" ],
    },
  },
  {
    // Without `files`, they are general rules for all files
    rules: {
      "style/semi": [ "error", "never" ],
    },
  }
);
```

We also provided a `overrides` options in each integration to make it easier:

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint({
  vue: {
    overrides: {
      "vue/operator-linebreak": [ "error", "before" ],
    },
  },
  typescript: {
    overrides: {
      "ts/consistent-type-definitions": [ "error", "interface" ],
    },
  },
  yaml: {
    overrides: {
      // ...
    },
  },
});
```

### Optional Configs

We provide some optional configs for specific use cases, that we don't include their dependencies by default.

#### Formatters

> [!WARNING]
> Experimental feature, changes might not follow semver.

Use external formatters to format files that ESLint cannot handle yet (`.css`, `.html`, etc). Powered by [`eslint-plugin-format`](https://github.com/antfu/eslint-plugin-format).

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint({
  formatters: {
    /**
     * Format CSS, LESS, SCSS files, also the `<style>` blocks in Vue
     * By default uses Prettier
     */
    css: true,
    /**
     * Format HTML files
     * By default uses Prettier
     */
    html: true,
    /**
     * Format Markdown files
     * Supports Prettier and dprint
     * By default uses Prettier
     */
    markdown: "prettier"
  }
});
```

Running `npx eslint` should prompt you to install the required dependencies, otherwise, you can install them manually:

```bash
npm i -D eslint-plugin-format
```

#### React

To enable React support, you need to explicitly turn it on:

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint({
  react: true,
});
```

Running `npx eslint` should prompt you to install the required dependencies, otherwise, you can install them manually:

```bash
npm i -D eslint-plugin-react eslint-plugin-react-hooks eslint-plugin-react-refresh
```

#### Svelte

To enable svelte support, you need to explicitly turn it on:

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint({
  svelte: true,
});
```

Running `npx eslint` should prompt you to install the required dependencies, otherwise, you can install them manually:

```bash
npm i -D eslint-plugin-svelte
```

#### Astro

To enable astro support, you need to explicitly turn it on:

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint({
  astro: true,
});
```

Running `npx eslint` should prompt you to install the required dependencies, otherwise, you can install them manually:

```bash
npm i -D eslint-plugin-astro
```

#### UnoCSS

To enable UnoCSS support, you need to explicitly turn it on:

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint({
  unocss: true,
});
```

Running `npx eslint` should prompt you to install the required dependencies, otherwise, you can install them manually:

```bash
npm i -D @unocss/eslint-plugin
```

### Optional Rules

This config also provides some optional plugins/rules for extended usage.

#### `perfectionist` (sorting)

This plugin [`eslint-plugin-perfectionist`](https://github.com/azat-io/eslint-plugin-perfectionist) allows you to sorted object keys, imports, etc, with auto-fix.

The plugin is installed but no rules are enabled by default.

It's recommended to opt-in on each file individually using [configuration comments](https://eslint.org/docs/latest/use/configure/rules#using-configuration-comments-1).

```js
/* eslint perfectionist/sort-objects: "error" */
const objectWantedToSort = {
  a: 2,
  b: 1,
  c: 3,
};
/* eslint perfectionist/sort-objects: "off" */
```

### Type Aware Rules

You can optionally enable the [type aware rules](https://typescript-eslint.io/linting/typed-linting/) by passing the options object to the `typescript` config:

```js
// eslint.config.js
import eslint from "@kmblabs/config";

export default eslint({
  typescript: {
    tsconfigPath: "tsconfig.json",
  },
});
```

### Lint Staged

If you want to apply lint and auto-fix before every commit, you can add the following to your `package.json`:

```json
{
  "simple-git-hooks": {
    "pre-commit": "pnpm lint-staged"
  },
  "lint-staged": {
    "*": "eslint --fix"
  }
}
```

and then

```bash
npm i -D lint-staged simple-git-hooks

// to active the hooks
npx simple-git-hooks
```

## View what rules are enabled

I built a visual tool to help you view what rules are enabled in your project and apply them to what files, [eslint-flat-config-viewer](https://github.com/antfu/eslint-flat-config-viewer)

Go to your project root that contains `eslint.config.js` and run:

```bash
npx eslint-flat-config-viewer
```

## Versioning Policy

This project follows [Semantic Versioning](https://semver.org/) for releases. However, since this is just a config and involves opinions and many moving parts, we don't treat rules changes as breaking changes.

### Changes Considered as Breaking Changes

- Node.js version requirement changes
- Huge refactors that might break the config
- Plugins made major changes that might break the config
- Changes that might affect most of the codebases

### Changes Considered as Non-breaking Changes

- Enable/disable rules and plugins (that might become stricter)
- Rules options changes
- Version bumps of dependencies

## FAQ

### Prettier?

[Why I don't use Prettier](https://antfu.me/posts/why-not-prettier)

Well, you can still use Prettier to format files that are not supported well by ESLint yet, such as `.css`, `.html`, etc. See [formatters](#formatters) for more details.

### dprint?

[dprint](https://dprint.dev/) is also a great formatter that with more abilities to customize. However, it's in the same model as Prettier which reads the AST and reprints the code from scratch. This means it's similar to Prettier, which ignores the original line breaks and might also cause the inconsistent diff. So in general, we prefer to use ESLint to format and lint JavaScript/TypeScript code.

Meanwhile, we do have dprint integrations for formatting other files such as `.md`. See [formatters](#formatters) for more details.

### How to format CSS?

You can opt-in to the [`formatters`](#formatters) feature to format your CSS. Note that it's only doing formatting, but not linting. If you want proper linting support, give [`stylelint`](https://stylelint.io/) a try.

### I prefer XXX...

Sure, you can configure and override rules locally in your project to fit your needs. If that still does not work for you, you can always fork this repo and maintain your own.

## License

[MIT](./LICENSE) License &copy; 2019-PRESENT [Anthony Fu](https://github.com/antfu)