@wonse/eslint-js

Shared ESLint configuration for JavaScript projects using the new ESLint flat config.

Features

• 🎯 Optimized for modern JavaScript development
• 🔄 Uses the new ESLint flat config system
• 🎨 Integrates with Prettier for consistent code formatting
• ✅ Comprehensive test suite using ESLint's RuleTester
• 📦 Includes carefully selected plugins and rules:
  • eslint-plugin-import: Better import/export syntax handling
  • eslint-plugin-simple-import-sort: Automated import sorting
  • eslint-plugin-promise: Promise-related best practices
  • eslint-plugin-regexp: Regular expression safety and best practices

Installation

# Using npm
npm install --save-dev @wonse/eslint-js eslint

# Using yarn
yarn add --dev @wonse/eslint-js eslint

# Using pnpm
pnpm add -D @wonse/eslint-js eslint

Usage

Create an eslint.config.js file in your project root:

import jsConfig from '@wonse/eslint-js';

export default [
  ...jsConfig,
  // Your custom configurations (optional)
];

Configuration Details

The base configuration includes:

• Modern JavaScript features (ES2022)
• Module-based development
• Browser, ES2021, and Node.js globals
• Prettier integration for formatting
• Comprehensive set of plugins and rules

Extending the Configuration

You can extend or override the configuration in several ways:

1. Adding New Rules:

import jsConfig from '@wonse/eslint-js';

export default [
  ...jsConfig,
  {
    rules: {
      'no-console': 'off',
      'import/no-default-export': 'error',
    },
  },
];

2. Targeting Specific Files:

import jsConfig from '@wonse/eslint-js';

export default [
  ...jsConfig,
  {
    files: ['src/**/*.js'],
    rules: {
      'no-console': 'warn',
    },
  },
];

3. Adding Custom Plugins:

import jsConfig from '@wonse/eslint-js';
import somePlugin from 'eslint-plugin-some-plugin';

export default [
  ...jsConfig,
  {
    plugins: {
      'some-plugin': somePlugin,
    },
    rules: {
      'some-plugin/some-rule': 'error',
    },
  },
];

Included Rules

This configuration includes a carefully selected set of rules from various plugins:

JavaScript Best Practices

• Enforces strict equality (===) checks
• Prevents usage of var
• Encourages use of const where possible
• Warns about console statements
• Warns about debugger statements
• Warns about alert statements

Import/Export Rules

• Sorts imports automatically by groups:
  • Built-in Node.js modules
  • External packages
  • Internal packages (with @/ alias support)
  • Parent/sibling imports
  • Index imports
  • Object imports
  • Type imports
• Enforces consistent import ordering:
  • Alphabetical sorting within groups
  • Required newlines between groups
• Static analysis:
  • Prevents circular dependencies (max depth: 1)
  • Prevents self imports
  • Prevents useless path segments
  • Prevents absolute paths
  • Prevents webpack loader syntax
  • Prevents relative package imports
• Helpful warnings:
  • Warns about deprecated imports
  • Prevents mutable exports
  • Warns about unused modules
• Style guide:
  • No file extensions (except for .json)
  • Default exports are optional
  • Ensures imports come first in file
  • Prevents duplicate imports
  • Enforces newlines after imports

Promise Handling

• Enforces best practices for promises
• Prevents common async/await mistakes

Regular Expressions

• Ensures safe and optimal regex patterns
• Prevents common regex mistakes

Testing

This package includes a comprehensive test suite that verifies all included ESLint rules are working as expected. The tests use ESLint's RuleTester class to validate both valid and invalid code patterns for each rule.

Running Tests

# Using npm
npm test

# Using yarn
yarn test

# Using pnpm
pnpm test

Test Coverage

The test suite covers:

• JavaScript Best Practices (e.g., no-var, no-console)
• Import/Export Rules (e.g., simple-import-sort)
• Promise Handling (e.g., require-await)
• Code Quality Rules (e.g., sonarjs/no-identical-expressions)

Each rule is tested with:

• ✅ Valid code examples that should pass
• ❌ Invalid code examples that should fail
• 🔄 Autofix output where applicable

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT

Author

Wonse Shin (@shinwonse)