reviewing-type-safety

Type safety in TypeScript uses explicit type annotations, strict mode configuration, and type guards to prevent runtime errors. Enable strictNullChecks and Strict mode in tsconfig.json, annotate function parameters and return types, and use discriminated unions and type guards to narrow unsafe types like any and unknown.

unknown is a safe alternative to any that requires type narrowing before use, preventing accidental unsafe operations. any bypasses all type checking. Use unknown for untyped data sources and type guards to validate the actual type before accessing properties or methods.

Discriminated unions combine a literal type field with union types to enable exhaustive pattern matching. Define a common property that distinguishes each union member, then use type guards or switch statements to narrow the type safely and eliminate unsafe type assertions.

Yes. Incrementally add explicit type annotations, enable strictNullChecks, eliminate implicit any instances, replace unsafe any usage with unknown or specific types, and use type guards. This workflow applies to front-end and back-end projects and can be integrated into CI checks to enforce compliance.

Strict mode enables strictNullChecks, strictFunctionTypes, strictBindCallApply, strictPropertyInitialization, noImplicitAny, and other checks. It prevents null/undefined from being assigned to any type, catches implicit any declarations, and validates function signatures to eliminate entire categories of type errors.

Minimize type assertions; use type guards instead to safely narrow types. Type assertions bypass checks and hide errors. Reserve assertions only for cases where you have external knowledge the compiler lacks, and document why. Prefer type guards, discriminated unions, and unknown for safe type narrowing.