@thyi/eslint-config

@thyi/eslint-config

A comprehensive, modern ESLint configuration for JavaScript and TypeScript projects with React support

✨ Features

• 🔧 Zero-config setup - Works out of the box with sensible defaults
• ⚡ Modern ESLint Flat Config - Uses the latest ESLint configuration format
• 🎯 Dual configurations - Separate configs for Node.js and React/React Native projects
• 📱 React & React Native - Full support for React applications and React Native projects
• 🔷 TypeScript-first - Comprehensive TypeScript support with type-aware linting
• 🎨 Prettier integration - Seamless code formatting with Prettier
• 📦 Import organization - Automatic import sorting and grouping with TypeScript support
• 🚀 Performance optimized - Minimal overhead with intelligent rule selection

📋 What's Included

This package provides two specialized configurations:

Default Configuration

• ESLint Core Rules - Latest JavaScript/ES2022+ standards
• TypeScript - Type-aware linting with @typescript-eslint
• Node.js Globals - Built-in Node.js and Jest globals
• Import Management - Organized imports with eslint-plugin-import and eslint-import-resolver-typescript
• Code Formatting - Prettier integration with consistent styling
• Performance - Rules optimized for modern JavaScript engines

React Configuration (React/React Native)

• Everything from Default - Plus React-specific features
• React Rules - JSX, hooks, and React best practices
• React Native - Platform-specific rules and optimizations
• React Hooks - Comprehensive hooks linting
• React Native Globals - Mobile-specific globals and APIs

🚀 Quick Start

Installation

pnpm add -D @thyi/eslint-config

npm install --save-dev @thyi/eslint-config

yarn add --dev @thyi/eslint-config

bun add --dev @thyi/eslint-config

Configuration

1. Default (Node.js) Configuration

For Node.js projects, backend APIs, CLI tools, or any non-React JavaScript/TypeScript project:

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

export default config

2. React Configuration

For React applications, React Native projects, or any project using React:

// eslint.config.js
import config from '@thyi/eslint-config/react'

export default config

When to Use Which Configuration?

Project Type	Use	Example
Node.js APIs	Default	import config from '@thyi/eslint-config'
CLI Tools	Default	import config from '@thyi/eslint-config'
Backend Services	Default	import config from '@thyi/eslint-config'
Browser Libraries	Default	import config from '@thyi/eslint-config'
Vanilla JS/TS Apps	Default	import config from '@thyi/eslint-config'
Build Tools/Scripts	Default	import config from '@thyi/eslint-config'
React Web Apps	React	import config from '@thyi/eslint-config/react'
Next.js Apps	React	import config from '@thyi/eslint-config/react'
React Native Apps	React	import config from '@thyi/eslint-config/react'
Expo Apps	React	import config from '@thyi/eslint-config/react'

Simple rule: Use React config for React projects, Default config for everything else.

TypeScript Support

Both configurations include full TypeScript support. You must have a tsconfig.json file in your project root:

{
  "compilerOptions": {
    "target": "ES2022",
    "lib": ["ES2022"],
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "allowJs": true,
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true
  },
  "include": [
    "src/**/*",
    "tests/**/*",
    "*.config.js",
    "*.config.ts"
  ],
  "exclude": ["node_modules", "dist"]
}

Package.json Scripts

Add these scripts to your package.json:

{
  "scripts": {
    "lint": "eslint .",
    "lint:fix": "eslint . --fix",
    "lint:check": "eslint . --max-warnings 0"
  }
}

⚙️ Configuration

Custom Rules Override

To override or extend rules:

// For Non-React projects
import baseConfig from '@thyi/eslint-config'

export default [
  ...baseConfig,
  {
    rules: {
      // Override specific rules
      'no-console': 'error',
      '@typescript-eslint/no-unused-vars': 'error',
    }
  }
]

// For React projects
import baseConfig from '@thyi/eslint-config/react'

export default [
  ...baseConfig,
  {
    rules: {
      // Override specific rules
      'no-console': 'error',
      '@typescript-eslint/no-unused-vars': 'error',
      'react-native/no-inline-styles': 'off'
    }
  }
]

Environment-Specific Overrides

The configuration includes intelligent overrides for different file types:

• React files (.tsx, .jsx) - React-specific rules enabled
• Test files (*.test.*, *.spec.*) - Relaxed rules for testing
• JavaScript files (.js, .cjs, .mjs) - TypeScript rules disabled

File Ignoring

The configuration automatically ignores common build directories and files:

• .expo/
• .next/
• build/
• dist/
• coverage/
• html/
• node_modules/
• babel.config.js
• metro.config.js

🎨 Prettier Integration

This ESLint configuration is Prettier-friendly but doesn't enforce Prettier formatting rules. Instead, it:

• Disables conflicting rules - Uses eslint-config-prettier to turn off ESLint rules that conflict with Prettier
• Lets you control formatting - You configure Prettier separately according to your preferences
• Avoids rule conflicts - No fighting between ESLint and Prettier over formatting

Setting up Prettier

Use any Prettier configuration format (.prettierrc.js, prettier.config.js, etc.) in your project root with your preferred settings:

{
  "arrowParens": "always",
  "singleQuote": true,
  "printWidth": 100,
  "tabWidth": 2,
  "semi": false,
  "endOfLine": "lf",
  "trailingComma": "all"
}

Recommended Workflow

• ESLint handles code quality - Logic errors, unused variables, React rules, etc.
• Prettier handles formatting - Indentation, line breaks, quotes, etc.
• No conflicts - This config ensures they work together seamlessly

This approach gives you maximum flexibility while avoiding the performance overhead of running Prettier through ESLint.

🔧 IDE Integration

VS Code Setup

• Install the ESLint extension

• Add these settings to your VS Code settings.json:

{
  "editor.formatOnSave": true,
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": "explicit"
  },
  "[javascript][javascriptreact][typescript][typescriptreact]": {
    "editor.formatOnSave": false
  },
  "eslint.useFlatConfig": true
}

Other IDEs

• WebStorm: ESLint support is built-in, just ensure flat config is enabled
• Vim/Neovim: Use ale or nvim-lspconfig with ESLint language server
• Emacs: Use flycheck-eslint with flat config support

📚 Rule Categories

Core JavaScript Rules

• Code Quality: Prevents common bugs and anti-patterns
• Modern Syntax: Encourages ES2022+ features
• Performance: Rules that improve runtime performance
• Readability: Consistent code structure and naming

TypeScript Rules

• Type Safety: Strict type checking and null safety
• Modern TypeScript: Latest TypeScript features and patterns
• Performance: Type-aware optimizations
• Import Management: Type-only imports and module resolution

React Rules

• Hooks: Comprehensive React Hooks linting
• JSX: JSX-specific rules and accessibility
• Performance: React performance optimizations
• Modern Patterns: Latest React patterns and best practices

React Native Rules

• Platform APIs: React Native specific validations
• Performance: Mobile-specific optimizations
• Styling: StyleSheet and styling best practices

🚨 Common Issues

Flat Config Not Recognized

Ensure you're using ESLint v8.21.0 or higher and your config file is named eslint.config.js.

TypeScript Parsing Errors

Make sure your tsconfig.json is valid and includes all TypeScript files you want to lint.

Import Resolution Issues

The config includes TypeScript and Node.js import resolvers. For custom path mapping, update your tsconfig.json with proper paths configuration.

Performance Issues

For large projects, consider using projectService in your TypeScript parser options or implementing incremental linting.

"Project service not found" Errors

Using JavaScript config files (eslint.config.js, vite.config.js, etc.):

Ensure your tsconfig.json includes JavaScript files and has allowJs: true:

{
  "compilerOptions": {
    "allowJs": true,
    // ... other options
  },
  "include": [
    "src/**/*",
    "tests/**/*",
    "*.config.js",        // Include config files
    "*.config.ts"         // Include TypeScript config files too
  ]
}

Alternative: Create a dedicated tsconfig.eslint.json that extends your main config:

{
  "extends": "./tsconfig.json",
  "compilerOptions": {
    "allowJs": true
  },
  "include": [
    "src/**/*",
    "tests/**/*",
    "eslint.config.js",
    "vite.config.js",
    "*.config.js"
  ]
}

🤝 Contributing

Issues and pull requests are welcome! Please ensure your contributions:

• Follow the existing code style
• Include appropriate tests
• Update documentation as needed
• Follow semantic versioning for changes

📄 License

MIT © Theodros Yimer

🔗 Related Projects

• ESLint - Pluggable JavaScript linter
• Prettier - Opinionated code formatter
• TypeScript ESLint - TypeScript support for ESLint
• React ESLint Plugin - React specific linting rules