CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Commands

Testing:

npm test - Run all tests (linting, unit tests, coverage, TypeScript definitions)
npx ava test/<specific-test-file>.js - Run a specific test file
npx xo - Run linting only
npx tsd - Run TypeScript definition tests only

Benchmarking:

Chalk is a zero-dependency terminal string styling library built as a pure ESM module. Key architectural elements:

Core Files:
- source/index.js - Main entry point with the chalk factory and chainable API implementation
- source/utilities.js - Helper functions for string manipulation and color conversion
- source/vendor/ - Vendored dependencies (ansi-styles and supports-color) to avoid external dependencies
Internal Symbols:
- GENERATOR - Manages chalk instance creation and configuration
- STYLER - Handles style application and chaining
- IS_EMPTY - Tracks empty string optimization
API Design:
- Uses ES6 Proxy for dynamic property access (e.g., chalk.red.bold)
- Chainable API with lazy property definition for performance
- Supports nested styles with proper ANSI escape code management
- Template literal support via tagged template syntax
Color Level Detection:
- Automatically detects terminal color support (levels 0-3)
- Separate instances for stdout and stderr with independent color levels
- Can be overridden via new Chalk({level: n}) or FORCE_COLOR environment variable

This is a pure ESM package (v5+) - use import not require
Maintain zero production dependencies - vendor any required modules
All style properties are dynamically generated via Proxy - there's no hardcoded list
Performance is critical - run benchmarks before/after changes to core functionality
The codebase uses symbols for private properties to prevent collisions
Template literal processing has special handling for newlines and empty strings