Javascript Expert

This is a comprehensive JavaScript development skill built around TDD and modern ES6+ practices. It pushes you to write tests first, handle async operations with proper error boundaries, and avoid common security pitfalls like XSS and prototype pollution. The source material is thorough with actual code examples for testing patterns in Vitest and Jest, async/await error handling, and performance optimization strategies. It's opinionated in a good way: const over var, async/await over raw promises, never swallow errors silently. Use this when you want guardrails that enforce clean patterns rather than just syntax help.