What are TypeScript Generics? Give examples of their use

What are Generics?

Generics allow functions, interfaces, and classes to accept type parameters, enabling code reuse while maintaining type safety.

Basic Example

// Without generics: only handles numbers
function identity(arg: number): number {
  return arg
}

// With generics: handles any type
function identity<T>(arg: T): T {
  return arg
}

identity<string>('hello') // type: string
identity<number>(42)      // type: number

Practical Use Case: API Response Wrapper

interface ApiResponse<T> {
  data: T
  error: string | null
  status: number
}

// Specify data type when using
type UserResponse = ApiResponse<{ id: number; name: string }>