What are generics and where have you actually used them?

Generics are a mechanism in programming languages (such as TypeScript, Java) that allows creating components that work with different data types while maintaining type safety.

In frontend development with TypeScript, I used generics to create versatile components and functions. For example, a generic function for working with arrays:

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

const firstNumber = getFirstElement<number>([1, 2, 3]);
const firstString = getFirstElement<string>(['a', 'b', 'c']);

I also used generics for typing React components so they could accept props with different data types, ensuring reusability and type safety.