← Back to all Posts

Getting Started with TypeScript Generics

typescript types javascript

What Are Generics?

Generics allow you to create reusable components that can work with multiple types rather than a single one. They provide a way to make components "type-safe" without sacrificing flexibility.

Basic Syntax

function identity<T>(arg: T): T {
  return arg;
}

const output = identity<string>("myString");

Generic Interfaces

interface GenericIdentityFn<T> {
  (arg: T): T;
}

function identity<T>(arg: T): T {
  return arg;
}

const myIdentity: GenericIdentityFn<number> = identity;

Generic Constraints

Sometimes you want to limit the types that can be passed to a generic function:

interface HasLength {
  length: number;
}

function logLength<T extends HasLength>(arg: T): T {
  console.log(arg.length);
  return arg;
}

Why Use Generics?

  • Type safety at compile time
  • Reusability without any
  • Better IDE support with autocompletion

Generics are one of the most powerful features of TypeScript. Master them, and you'll write much more robust code.