Narrow nested object based on value type

[cinder flame]

I'm looking for a way to take a nested object type and narrow it to just the leaf keys where their value is type T

type Input = {
  str: string,
  other: {
    int: number
  },
  foo: {
    bar: number,
    baz: string  
  },
}

// DeepNarrowByType<Input, string>; ???

type Output = {
  str: string,
  foo: {
    baz: string  
  },
}

[prisma portal]

something like this?

[heady hamlet]

that_guy977#0

Playground Link

Preview:ts ... type DeepNarrowByType<T, V> = T extends V ? T : { [K in keyof T as T[K] extends V ? K : T[K] extends object ? {} extends DeepNarrowByType<T[K], V> ? never : K : never]: DeepNarrowByType<T[K], V> } ...

[cinder flame]

Aha yes. That's it. I couldn't quite work out the syntax for recursively narrowing. Thank you.