Conditional Types

Conditional Types are a way to create a type that depends on a condition, where the type to be created is determined based on the result of the condition. They are defined using the extends keyword and a ternary operator to conditionally choose between two types.

type IsArray<T> = T extends any[] ? true : false;

const myArray = [1, 2, 3];
const myNumber = 42;

type IsMyArrayAnArray = IsArray<typeof myArray>; // Type true
type IsMyNumberAnArray = IsArray<typeof myNumber>; // Type false