Lint Command

The itty lint command runs ESLint with TypeScript-optimized rules and smart configuration detection. It automatically falls back to built-in configuration when no local ESLint config exists.

Basic Usage

itty lint                     # Lint all TypeScript files
itty lint --fix              # Auto-fix issues
itty lint src/ lib/          # Lint specific directories
itty lint --quiet            # Show only errors

How it Works

1. Detects ESLint configuration in your project
2. Falls back to built-in config if none found
3. Runs ESLint with TypeScript support
4. Reports issues with clear, actionable messages
5. Auto-fixes when possible (with --fix)

Built-in Configuration

When no local ESLint config is found, itty-packager uses a TypeScript-optimized configuration:

• TypeScript ESLint parser for accurate type checking
• Recommended rules for TypeScript projects
• Import/export validation for modern modules
• Code style consistency with Prettier compatibility
• Performance-optimized for fast execution

Configuration Options

--fix

Automatically fix issues

• Default: false
• Example: --fix

Attempts to automatically fix linting issues where possible.

--format

Output format

• Default: stylish
• Options: stylish, compact, json, unix
• Example: --format=json

Controls how linting results are displayed.

--quiet

Show only errors

• Default: false
• Example: --quiet

Suppresses warnings and only shows error-level issues.

Custom Configuration

You can extend the built-in configuration in your project:

Using .eslintrc.js

module.exports = {
  extends: ['itty-packager/eslint-config'],
  rules: {
    // Your custom rules
    'no-console': 'warn'
  }
}

Using ESM Configuration

// eslint.config.mjs
import { createConfig } from 'itty-packager/lib/configs/createConfig.mjs'

export default createConfig({
  rules: {
    // Your custom rules
    'prefer-const': 'error'
  }
})

Using package.json

{
  "eslintConfig": {
    "extends": ["itty-packager/eslint-config"],
    "rules": {
      "no-unused-vars": "error"
    }
  }
}

Examples

Basic Linting

# Lint all TypeScript files
itty lint

Auto-fix Issues

# Fix what can be fixed automatically
itty lint --fix

Specific Directories

# Lint only certain directories
itty lint src/ test/

CI/CD Pipeline

# Quiet mode for clean CI output
itty lint --quiet --format=compact

JSON Output

# Machine-readable output
itty lint --format=json > lint-results.json

Integration with Scripts

Add to your package.json:

{
  "scripts": {
    "lint": "itty lint",
    "lint:fix": "itty lint --fix",
    "lint:ci": "itty lint --quiet",
    "lint:check": "itty lint --format=json"
  }
}

IDE Integration

The built-in ESLint config works with popular editors:

VS Code

Install the ESLint extension and add to .vscode/settings.json:

{
  "eslint.validate": ["typescript", "javascript"],
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": true
  }
}

WebStorm

ESLint is automatically detected and configured when using the built-in config.

Common Rules

The built-in configuration includes these key rules:

• @typescript-eslint/no-unused-vars - Catches unused variables
• @typescript-eslint/no-explicit-any - Warns about any usage
• @typescript-eslint/prefer-nullish-coalescing - Modern null checking
• import/no-unresolved - Validates import paths
• prefer-const - Enforces immutability where possible

Error Handling

Common linting scenarios:

• No config found - Automatically uses built-in TypeScript config
• Parse errors - Shows TypeScript compilation issues
• Rule violations - Clear messages with fix suggestions
• Plugin missing - Helpful installation instructions

Performance

The lint command is optimized for speed:

• Incremental checking when possible
• Parallel processing for multiple files
• Smart caching to avoid re-linting unchanged files
• Minimal rule set focused on essential issues