How do I map values in Typescript?

Question

I am trying to make an enrich-object function, but I can't figure out how to change the type of the values inside a Type.

So given the following types

{ a: string, c: number }
{ a: boolean, b: Cow }

I want the returned type to respectively be

{ a: Container<string>, c: Container<number> }
{ a: Container<boolean>, b: Container<Cow> }

The closest I've gotten is using the Record util

enrich<T>(value: T) {
  // create mapped object by iterating over object keys
  return container as Record<T, Container<any>>
}

But that changes all of the objects value types to Container<any>, erasing part of the context from the input.

Answer 1

You can use mapped types for this:

type Enrich<T> = {[key in keyof T]: Container<T[key]>};