TypeScript Strict Mode

Catch errors at build time, not in production.

When to Use This Skill

• Starting a new TypeScript project
• Tightening an existing codebase
• Preventing any types from leaking through
• Want compile-time guarantees for runtime safety

Core Concepts

1. Strict mode - Enables all strict type checks
2. Index safety - Array access returns T | undefined
3. Exhaustiveness - Compiler ensures all cases handled
4. Branded types - Prevent mixing up IDs and primitives

TypeScript Implementation