TypeScript Generics: Building Reusable, Type-Safe Utilities

Generics are the difference between a helper that works for one type and one that works for all of them — safely.

The problem generics solve

Without generics, you either duplicate logic per type or give up on typing by falling back to any. Both are bad.

Reading and writing generic types

A generic function takes a type parameter and returns it — so callers preserve the exact type they pass in, no casting required.

Constraints keep it honest

Use extends to require that a generic has certain properties, giving you safety and autocomplete without losing flexibility.

Wrapping up

Generics are what make truly reusable libraries possible. Learn them and your utility layer stops being a source of bugs.