TypeScript Development Skill

TypeScript 5.x development skill for Claude Code agents, providing comprehensive type system patterns, generics, utility types, and strict mode best practices.

Overview

This skill is loaded by backend-developer or frontend-developer agents when working with TypeScript projects. It provides:

• SKILL.md (~450 lines): Quick reference for daily development
• REFERENCE.md (~800 lines): Comprehensive guide for advanced patterns

When This Skill Loads

Automatically detected when:

• tsconfig.json exists in project root
• package.json contains typescript as a dependency
• .ts or .tsx files are present
• NestJS, Angular, or typed React frameworks detected

Contents

SKILL.md (Quick Reference)

Essential patterns for everyday TypeScript development:

• Basic types, interfaces, and type aliases
• Union, intersection, and literal types
• Type narrowing and guards
• Generics with constraints
• Essential utility types (Partial, Pick, Omit, Record, etc.)
• Function types and overloads
• tsconfig.json configuration
• Module patterns and imports
• Common patterns (discriminated unions, branded types)
• Error handling with types

REFERENCE.md (Comprehensive Guide)

Advanced topics for complex scenarios:

1. Advanced Generics - Recursive types, variadic tuples, const type parameters
2. Conditional Types - Distribution, infer keyword, constraint narrowing
3. Mapped Types Deep Dive - Key remapping, property modifiers, deep types
4. Template Literal Types - String manipulation, type inference
5. Declaration Files - Writing .d.ts, augmenting modules
6. Module Augmentation - Extending third-party and global types
7. Decorators - Modern TS 5.0+ syntax and legacy patterns
8. Advanced tsconfig - Project references, path aliases, strict options
9. Type Inference Patterns - Contextual typing, const assertions, satisfies
10. Build Tool Integration - esbuild, SWC, Vite configuration
11. Migration from JavaScript - Progressive migration strategies
12. Performance Optimization - Type-level and build performance

Usage

Agent Integration

Agents can reference this skill for TypeScript-specific guidance:

# In agent context
skill: developing-with-typescript
reference: SKILL.md  # Quick patterns
# or
reference: REFERENCE.md  # Deep dive

Common Tasks

Task	Reference
Add types to function	SKILL.md > Functions
Create type guard	SKILL.md > Type Guards
Configure strict mode	SKILL.md > tsconfig.json
Write declaration file	REFERENCE.md > Declaration Files
Migrate from JavaScript	REFERENCE.md > Migration

Version Compatibility

• TypeScript: 5.0+
• Node.js: 18+ (for modern ESM support)
• Build Tools: esbuild, SWC, tsc, Vite

Related Skills

• nestjs-framework - NestJS-specific TypeScript patterns
• react - React with TypeScript (TSX)
• prisma - Prisma ORM TypeScript integration

Contributing

When updating this skill:

1. Keep SKILL.md under 500 lines for quick reference
2. Place advanced topics in REFERENCE.md
3. Focus on TypeScript 5.x patterns
4. Do NOT include React-specific types (use react skill)
5. Test code examples for correctness

License

MIT - Part of the Ensemble Plugins ecosystem