Type definition of arrays

Question

A TypeScript beginner here.

I have the following type definition for a function:

type MappingCallback<A extends any[], B extends any[]> = (from: A[0], to: B[0]) => boolean

interface ArrayToCombine<A extends any[], B extends any[]> {
  array: B
  mapping: MappingCallback<A, B>
  propertyName: string
}

declare function augmentArray<A extends any[], B extends any[], C extends any[]>(
  base: A,
  arrays: [ArrayToCombine<A, B>, ArrayToCombine<A, C>]
) : A

export default augmentArray

Right now, if I add another element to the arrays parameter, I also have to add a new ArrayToCombine<A, ?> element to the type definition to work. Is there a way to make it dynamic, so each element in the arrays list will inherit the correct type, (the type is coming from the array property inside ArrayToCombine interface)

(Also, you can see I have to define extends any[] on each generic type, otherwise, VSCode underlines it as an error)

Please tell me if I should clarify something, or you need more info!

You *might* want `declare function augmentArray( base: A, arrays: { [K in keyof BB]: ArrayToCombine > }): A;`, but I can't tell if it matches the use case (ideally your [mcve] would include how you plan to call this thing). And automatically inferring tuple types instead of array types is still a bit maddening; you might need to call a `tuple()` function as described in the TS3.0 update of [this answer](https://stackoverflow.com/questions/45251664/typescript-derive-union-type-from-tuple-array-values/45257357#45257357). — jcalz, Aug 30 '19 at 16:23

Type definition of arrays

0 Answers0