@jmlweb/eslint-config-base

Strict ESLint flat config for TypeScript projects. Extends @jmlweb/eslint-config-base-js with strict type-checked rules.

🔧 Maintenance mode: only dependency and security updates, no new rules. For new projects use @jmlweb/oxlint-config-base. To move an existing project, see the migration guide.

✨ Features

• 🔒 Strict type checking: strictTypeChecked and stylisticTypeChecked from typescript-eslint, with projectService
• 🛡️ No any: no-explicit-any is an error
• 📦 Type-only imports: inline type style, plus automatic import and export sorting
• 🎯 Opinionated: no enums (use const maps), no default exports, no parameter mutation
• 🎨 Prettier compatible: disables rules that conflict with Prettier

📦 Installation

npm install --save-dev @jmlweb/eslint-config-base eslint @eslint/js typescript-eslint eslint-config-prettier eslint-plugin-simple-import-sort

@jmlweb/eslint-config-base-js is a regular dependency and installs automatically.

💡 Upgrading? See the Migration Guide.

🚀 Quick Start

// eslint.config.js
import baseConfig from '@jmlweb/eslint-config-base';

export default [
  ...baseConfig,
  // Project-specific overrides
];

💡 Examples

Test overrides and ignores

// eslint.config.js
import baseConfig from '@jmlweb/eslint-config-base';

export default [
  ...baseConfig,
  {
    files: ['**/*.test.ts', '**/*.test.tsx'],
    rules: {
      '@typescript-eslint/no-explicit-any': 'off',
      'no-console': 'off',
    },
  },
  {
    ignores: ['dist/', 'build/', 'node_modules/'],
  },
];

Allow default exports in config files

// eslint.config.js
import baseConfig from '@jmlweb/eslint-config-base';

export default [
  ...baseConfig,
  {
    files: ['*.config.ts', '*.config.js'],
    rules: {
      'no-restricted-exports': 'off',
    },
  },
];

Less strict

// eslint.config.js
import baseConfig from '@jmlweb/eslint-config-base';

export default [
  ...baseConfig,
  {
    files: ['**/*.ts', '**/*.tsx'],
    rules: {
      '@typescript-eslint/no-explicit-any': 'warn',
      '@typescript-eslint/consistent-type-imports': 'off',
    },
  },
];

📋 Configuration Details

Applied to **/*.ts and **/*.tsx (plus the JavaScript rules from base-js for .js, .mjs and .cjs).

Included

• ✅ typescript-eslint recommended, strictTypeChecked and stylisticTypeChecked
• ✅ parserOptions.projectService: true (requires a tsconfig.json)
• ✅ Import and export sorting, Prettier conflict resolution
• ✅ All rules from @jmlweb/eslint-config-base-js

Key rules

| Rule | Setting | | -------------------------------------------------- | ------------------------------------------------ | | @typescript-eslint/no-explicit-any | error | | @typescript-eslint/explicit-function-return-type | off (return types are inferred) | | @typescript-eslint/no-unused-vars | error, _-prefixed args and variables ignored | | @typescript-eslint/consistent-type-imports | error, type-imports with inline fix | | @typescript-eslint/consistent-type-definitions | error, prefer type | | @typescript-eslint/no-require-imports | error | | @typescript-eslint/naming-convention | error, see below | | no-restricted-syntax (TSEnumDeclaration) | error, use const maps | | no-restricted-exports | error, no default exports | | no-param-reassign | error, including properties |

Naming: types PascalCase; variables camelCase or UPPER_CASE (exported consts may also be PascalCase); functions camelCase.

🔄 Import Sorting

Imports are sorted and type-only imports are enforced.

Before:

import { Component } from './component';
import React, { useState } from 'react';
import { User } from './types';
import fs from 'fs';

After eslint --fix:

import fs from 'fs';
import React, { useState } from 'react';
import { type User } from './types';
import { Component } from './component';

🎯 When to Use

• ✅ TypeScript projects that want strict, type-aware linting
• ✅ Teams that want one consistent style (named exports, const maps, immutability)
• ✅ A base for the React, Node.js and Astro configs

For JavaScript-only projects use @jmlweb/eslint-config-base-js. For React, Node.js or Astro use -react, -node or -astro. For new projects prefer @jmlweb/oxlint-config-base.

🔧 Extending the Configuration

Spread the config, then add objects after it. Later entries win.

// eslint.config.js
import baseConfig from '@jmlweb/eslint-config-base';

export default [
  ...baseConfig,
  {
    files: ['**/*.ts'],
    rules: {
      '@typescript-eslint/explicit-function-return-type': 'error',
    },
  },
];

📝 Usage with Scripts

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

npm run lint

📋 Requirements

• Node.js >= 22.12.0
• ESLint ^9.0.0 || ^10.0.0 (flat config)
• TypeScript project with a tsconfig.json (versions supported by typescript-eslint 8)

📦 Peer Dependencies

• eslint (^9.0.0 || ^10.0.0)
• @eslint/js (^9.0.0 || ^10.0.0)
• typescript-eslint (^8.0.0)
• eslint-config-prettier (^9.1.0 || ^10.0.0)
• eslint-plugin-simple-import-sort (^12.0.0 || ^13.0.0 || ^14.0.0)

🔗 Related Packages

• @jmlweb/eslint-config-base-js: JavaScript foundation (extended by this package)
• @jmlweb/eslint-config-react: React config that extends this one
• @jmlweb/eslint-config-node: Node.js config that extends this one
• @jmlweb/eslint-config-astro: Astro config that extends this one
• @jmlweb/oxlint-config-base: Oxlint equivalent, recommended for new projects
• @jmlweb/tsconfig-base: TypeScript config
• @jmlweb/prettier-config-base: Prettier config (maintenance mode)

🔄 Migration Guide

2.x to 3.0

Node.js 18 and 20 are end-of-life. Node.js >= 22.12.0 is now required: it is the first Node.js 22 release that can require() ES modules without a flag, which the CommonJS build needs to load ESM-only plugins. Peer ranges were also widened (eslint-plugin-simple-import-sort 13 and 14).

1. Upgrade Node.js to 22.12.0 or later.
2. Update the package: npm install --save-dev @jmlweb/eslint-config-base@latest.

See the Changelog.

📄 License

MIT