typescript-best-practices

To make illegal states unrepresentable in TypeScript, use discriminated unions, branded types, and const assertions to enforce rigorous compile-time type safety and prevent invalid state combinations.

Refactoring JavaScript to type-safe TypeScript requires a type-first development approach, defining interfaces before implementation, and integrating Zod for robust runtime validation at API boundaries.

Zod validation integrates with TypeScript by defining robust schemas that validate runtime data at API boundaries, ensuring incoming data matches expected types and preventing unpredictable runtime errors.

You need runtime validation in a TypeScript codebase when handling external API data, utilizing Zod schema definitions to ensure unpredictable runtime inputs match your compile-time type definitions.

Exhaustive handling of states in TypeScript is ensured by applying discriminated unions and type-first development patterns, which guide the creation of robust, maintainable, and error-resistant codebases.

TypeScript type safety prevents many compile-time bugs by making illegal states unrepresentable, but runtime validation with Zod is still required for external data to eliminate unpredictable runtime errors completely.