# Javascript Typescript

> Use for JavaScript ES6+ development, TypeScript advanced types, Node.js backend patterns, async/await, promises, testing with Jest/Vitest, and modern tooling. Covers generics, conditional types, mapped types, and enterprise patterns.

- Skill: `henryhawke/javascript-typescript` (Agent Skill, multi-file: 6 files)
- Install (CLI): `npx skillmds@latest add henryhawke/javascript-typescript`
- Raw SKILL.md: https://api.skillmd.com/api/skills/henryhawke/javascript-typescript/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: henryhawke (https://skillmd.com/u/henryhawke)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/henryhawke/javascript-typescript

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# JavaScript & TypeScript

## When to use
- Write modern JavaScript (ES6+)
- Implement TypeScript with advanced types
- Build Node.js backend services
- Debug async patterns and promises
- Set up testing with Jest/Vitest

## JavaScript
- ES6+ features: async/await, destructuring, modules
- Promise patterns and error handling
- Event loop and concurrency model
- Browser and Node.js compatibility
- Performance optimization

## TypeScript
- Advanced generics and constraints
- Conditional and mapped types
- Template literal types
- Utility types and type inference
- Strict type safety patterns
- Declaration files and module augmentation

## Node.js
- Express/Fastify middleware patterns
- Stream processing
- Worker threads
- Error handling strategies
- Authentication and authorization