TypeScript for Frontend (Part 3): Generics, Constraints, and Inference

Generics let you write functions and types that work over many types while keeping full type safety. Used well, they reduce duplication and catch errors at compile time. This post covers generic functions, constraints with extends, inference, and patterns you'll use daily in Vue, API layers, and utilities.

Generic functions and type parameters

A type parameter is a placeholder for a type. You declare it in angle brackets and use it in the function signature: