Generics in typescript

Generics create reusable components that work with multiple types while maintaining type safety. They're used in functions, classes, and interfaces. Constraints (extends) limit generic types. Built-in generics include Array<T>, Promise<T>, Record<K,V>.

Example

function first<T>(arr: T[]): T | undefined {
  return arr[0];
}

const num = first([1, 2, 3]);    // number
const str = first(['a', 'b']);   // string

The generic T is inferred from the argument, providing correct return types automatically.

Previous Next