how to map TypeScript union types

Hi, how can we map TypeScript union types in kotlinjs ?

For example in ReactQuery there are signatures like this:

queryClient.setQueryData(queryKey, updater)

queryKey: QueryKey
updater: TData | (oldData: TData | undefined) => TData

(I asked ReactQuery to avoid such signatures: https://github.com/TanStack/query/issues/3740 )

[turansky]

@frhack You can close it as author (and others, which solved for you)

[frhack]

Usually we use more flexible signature. In described case it will be:

updater: (oldData: TData?) -> TData

In common initial signature is fine. Looks like it will work in Kotlin, when unions types will be supported.

Indeed the provided signature is more general and so to pass a simple value I just passed a lambda that returns that value

I got an answer from ReactQuery team:

in v4, the signature has been changed to:

updater: (oldData: TData | undefined) => TData | undefined

https://github.com/TanStack/query/issues/3740