What is a conditional type’s behavior when given a union type as the checked type parameter?

Question

TypeScript Professional — Hard

What is a conditional type’s behavior when given a union type as the checked type parameter?

Accepted Answer

When a conditional type is given a union type as the checked type parameter, it distributes over each union member separately when using a naked type parameter. This means that the conditional type is applied individually to each member of the union, rather than as a whole.