Runtime Response Validation with Schema Libraries
TypeScript types evaporate at runtime, so a fetch response typed as User[] can be null or malformed. Schema libraries like Zod give static types and runtime guards from one contract. The footgun is using as instead of parse, silently reintroducing crashes.
TypeScript types vanish at runtime, so a fetch typed as User[] can return null or malformed data without complaint. Schema libraries like Zod let you declare a shape once and get both a static type and a runtime validator. Apply this at every untrusted boundary: HTTP responses, webhook bodies, config files, and user uploads. The footgun is treating parse as a dev-only check and falling back to as in production, which silently resurrects the runtime crashes the schema was meant to prevent.
Read the original → zod.dev
- #typescript
- #zod
- #validation
- #runtime
- #api
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