嵌套对象的打字稿限制

Question

I have following general-purpose type definition:

export interface genericParameter {
    [k: string]: any
}

Is there a clever way to restrict such signature from assigning nested objects? For example I'd be happy to accept this type:

{
  prop1: 'val1',
  prop2: 123,
}

But not this:

{
  Obj1: {prop1: 'val1'},
  Obj2: {prop2: 123},
}

Thanks for any help!

---EDIT---

Considering following:

[k: string]: string | number | /* unmanageable list */

Seems not an option I guess

Answer 1

There is no way to tell typescript that can't be of a given type (not without done conditional types and a function anyway). In this case though, the list of primitive types is pretty short, so we can just enumerate the allowed types in a union

export interface genericParameter {
    [k: string]: number | string | boolean
}

Edit

As @tj-crowder points out, if you are going to use this type in many places, you might want to declare a type alias for the union (especially since what is a primitive may evolve over time with the addition of BigInt in the future)

type primitive = number | string | boolean;
export interface genericParameter {
    [k: string]: primitive
}