Keyof nested child objects

Question

I have a recursively typed object that I want to get the keys of and any child keys of a certain type.

For instance. Below I want to get a union type of:

<         


        

Answer 1

Here's an infinitely recursive solution:

type Paths = T extends RouteList
  ? keyof T | { [K in keyof T]: Paths }[keyof T]
  : never

type ListPaths = Paths // -> "/parent" | "/another" | "/child"

Tested on Typescript v3.5.1. Also you need to remove the type annotation from the list variable as advised by @jcalz.