@iz7n/eslint-config NPM

@iz7n/eslint-config

Aimed to be used with Prettier
Reasonable defaults, best practices, only one line of config
Designed to work with TypeScript, JSX, Svelte, JSON, etc. Out-of-box.
Opinionated, but very customizable
ESLint Flat config, compose easily!
Style principle: Minimal for reading, stable for diff, consistent
- Sorted imports, dangling commas
- Double quotes, semi
Respects .gitignore by default
Supports ESLint v9 or v8.50.0+

Usage

Starter Wizard

We provided a CLI tool to help you set up your project, or migrate from the legacy config to the new flat config with one command.

npx @iz7n/eslint-config@latest

Manual Install

If you prefer to set up manually:

pnpm i -D eslint @iz7n/eslint-config

And create eslint.config.mjs in your project root:

// eslint.config.mjs
import iz7n from '@iz7n/eslint-config'

export default iz7n()

If you still use some configs from the legacy eslintrc format, you can use the @eslint/eslintrc package to convert them to the flat config.

// eslint.config.mjs
import iz7n from '@iz7n/eslint-config'
import { FlatCompat } from '@eslint/eslintrc'

const compat = new FlatCompat()

export default iz7n(
  {
    ignores: [],
  },

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

  // Other flat configs...
)

Note that .eslintignore no longer works in Flat config, see customization for more details.

Add script for package.json

For example:

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

Customization

Since v1.0, we migrated to ESLint Flat config. It provides much better organization and composition.

Normally you only need to import the iz7n preset:

// eslint.config.js
import iz7n from '@iz7n/eslint-config'

export default iz7n()

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

// eslint.config.js
import iz7n from '@iz7n/eslint-config'

export default iz7n({
  // TypeScript and Svelte are auto-detected, you can also explicitly enable them:
  typescript: true,
  svelte: true,

  // Disable jsonc support
  jsonc: false,

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

The iz7n factory function also accepts any number of arbitrary custom config overrides:

// eslint.config.js
import iz7n from '@iz7n/eslint-config'

export default iz7n(
  {
    // Configures for iz7n'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:

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.

// eslint.config.js
import {
  combine,
  comments,
  ignores,
  imports,
  javascript,
  jsdoc,
  jsonc,
  node,
  sortPackageJson,
  sortTsconfig,
  typescript,
  unicorn,
} from '@iz7n/eslint-config'

export default combine(
  ignores(),
  javascript(/* Options */),
  comments(),
  node(),
  jsdoc(),
  imports(),
  unicorn(),
  typescript(/* Options */),
  jsonc(),
)

Check out the configs and factory for more details.

Thanks to 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/*`	`import-x/*`	eslint-plugin-import-x
`node/*`	`n/*`	eslint-plugin-n
`ts/*`	`@typescript-eslint/*`	@typescript-eslint/eslint-plugin

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

-// 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 svelte/* rules would only be enabled in .svelte files. If you want to override the rules, you need to specify the file extension:

// eslint.config.js
import iz7n from '@iz7n/eslint-config'

export default iz7n(
  {
    svelte: true,
    typescript: true
  },
  {
    // Remember to specify the file glob here, otherwise it might cause the svelte plugin to handle non-svelte files
    files: ['**/*.svelte'],
    rules: {
      'svelte/valid-prop-names-in-kit-pages': 'off',
    },
  },
  {
    // Without `files`, they are general rules for all files
    rules: {
      'style/semi': ['error', 'never'],
    },
  }
)

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

// eslint.config.js
import iz7n from '@iz7n/eslint-config'

export default iz7n({
  svelte: {
    overrides: {
      'svelte/valid-prop-names-in-kit-pages': 'off,
    },
  },
  typescript: {
    overrides: {
      'ts/consistent-type-definitions': ['error', 'interface'],
    },
  },
  yaml: {
    overrides: {
      // ...
    },
  },
})

Config Composer

Since v2.10.0, the factory function iz7n() returns a FlatConfigComposer object from eslint-flat-config-utils where you can chain the methods to compose the config even more flexibly.

// eslint.config.js
import iz7n from '@iz7n/eslint-config'

export default iz7n()
  .prepend(
    // some configs before the main config
  )
  // overrides any named configs
  .override(
    'iz7n/imports',
    {
      rules: {
        'import/order': ['error', { 'newlines-between': 'always' }],
      }
    }
  )
  // rename plugin prefixes
  .renamePlugins({
    'old-prefix': 'new-prefix',
    // ...
  })
// ...

Svelte

Svelte support is detected automatically by checking if svelte is installed in your project. You can also explicitly enable/disable it:

// eslint.config.js
import iz7n from '@iz7n/eslint-config'

export default iz7n({
  svelte: true
})

Optional Rules

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

`command`

Powered by eslint-plugin-command. It is not a typical rule for linting, but an on-demand micro-codemod tool that triggers by specific comments.

For a few triggers, for example:

/// to-function - converts an arrow function to a normal function
/// to-arrow - converts a normal function to an arrow function
/// to-for-each - converts a for-in/for-of loop to .forEach()
/// to-for-of - converts a .forEach() to a for-of loop
/// keep-sorted - sorts an object/array/interface
... etc. - refer to the documentation

You can add the trigger comment one line above the code you want to transform, for example (note the triple slash):

/// to-function
const foo = async (msg: string): void => {
  console.log(msg)
}

Will be transformed to this when you hit save with your editor or run eslint . --fix:

async function foo(msg: string): void {
  console.log(msg)
}

The command comments are usually one-off and will be removed along with the transformation.

Type Aware Rules

You can optionally enable the type aware rules by passing the options object to the typescript config:

// eslint.config.js
import iz7n from '@iz7n/eslint-config'

export default iz7n({
  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:

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

and then

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

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

View what rules are enabled

antfu built a visual tool to help you view what rules are enabled in your project and apply them to what files, @eslint/config-inspector

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

npx @eslint/config-inspector

Versioning Policy

This project follows Semantic Versioning 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.