Know How to Reconstruct Types at Runtime

Overview

TypeScript types are erased at runtime, but sometimes you need to validate that runtime data matches your types. Use libraries like io-ts, zod, or runtypes to define schemas that provide both runtime validation and static types. This ensures your types match reality.

When to Use This Skill

• Validating data at runtime
• Parsing JSON with type safety
• Types need runtime checks
• Using io-ts, zod, or runtypes
• Building validation schemas

The Iron Rule

Use validation libraries like zod or io-ts to get both runtime validation and TypeScript types from a single source of truth.

Example with Zod