@t3n/eslint-configs

This monorepo provides the development environment for three packages with extensible ESLint configurations for Javascript, React and Typescript development in (not exclusively) the t3n.de domain.

Note: These packages use ESLint v9's flat config format. Make sure you're using ESLint v9 or later.

Packages

@t3n/eslint-config

Provides the extensible base eslint configuration for javascript projects.

Usage

In your project's eslint.config.js, add the following:

import baseConfig from '@t3n/eslint-config';
import { defineConfig } from 'eslint/config';

export default defineConfig([baseConfig]);

@t3n/eslint-config-react

Use this configuration alongside the base configuration if your project uses React.

Usage

In your project's eslint.config.js, add the following:

import baseConfig from '@t3n/eslint-config';
import reactConfig from '@t3n/eslint-config-react';
import { defineConfig } from 'eslint/config';

export default defineConfig([baseConfig, reactConfig]);

@t3n/eslint-config-typescript

Use this configuration alongside the base configuration if your project uses Typescript.

Usage

In your project's eslint.config.js, add the following:

import baseConfig from '@t3n/eslint-config';
import typescriptConfig from '@t3n/eslint-config-typescript';
import { defineConfig } from 'eslint/config';

export default defineConfig([baseConfig, typescriptConfig]);

Combined Usage (React + TypeScript)

For projects using both React and TypeScript:

import baseConfig from '@t3n/eslint-config';
import reactConfig from '@t3n/eslint-config-react';
import typescriptConfig from '@t3n/eslint-config-typescript';
import { defineConfig } from 'eslint/config';

export default defineConfig([baseConfig, reactConfig, typescriptConfig]);

ESM Projects and Import Extensions

When using these configurations in ESM projects (projects with "type": "module" in package.json), you may encounter ESLint errors about file extensions in import statements:

error  Unexpected use of file extension "js" for "./path/to/file.js"  import/extensions

This happens because Node.js ESM requires explicit file extensions (.js, .mjs) for relative imports, but the default import/extensions rule enforces omitting them.

Solution

To resolve this in your project's eslint.config.js, override the rule to allow .js extensions:

import baseConfig from '@t3n/eslint-config';
import { defineConfig } from 'eslint/config';

export default defineConfig([
  baseConfig,
  {
    rules: {
      'import/extensions': [
        'error',
        'ignorePackages',
        {
          js: 'always', // or 'ignorePackages' to allow .js extensions
          mjs: 'never',
          jsx: 'never',
          ts: 'never',
          tsx: 'never',
        },
      ],
    },
  },
]);

Alternatively, you can disable the rule entirely for your project:

import baseConfig from '@t3n/eslint-config';
import { defineConfig } from 'eslint/config';

export default defineConfig([
  baseConfig,
  {
    rules: {
      'import/extensions': 'off',
    },
  },
]);

Development

Install all necessary development dependencies by running npm install