Typescript: How to reference other prop of literal object, from within the object?

Question

How can I self reference a prop in typescript?

const Test = {
    a: { someProp: true },
    b: { ...Test.a, someOtherProp: true } //error: Block-scoped variable 'Test' used before its declaration.

}

here is a Playground Link

Answer 1

Use a getter:

const Test = {
    a: { someProp: true },
    get b() {
       return  { ...Test.a, someOtherProp: true }
    }
}

(This problem is not specific to TypeScript—it's how JavaScript works)