types-kit.deepget.md

Home > types-kit > DeepGet

DeepGet type

Get the deep specified value from T.

Signature:

export type DeepGet<
  T,
  K extends DeepKeys<T>,
> = K extends `${infer Head}.${infer Tail}`
  ? Head extends Keys<T>
    ? T[Head] extends infer V
      ? V extends V
        ? IsObject<V> extends true
          ? Tail extends DeepKeys<V>
            ? DeepGet<V, Tail>
            : never
          : // if the value of the parent property is not an object, like a?.b, then the value of b will be undefined
            undefined
        : never
      : never
    : never
  : K extends keyof T
  ? T[K]
  : never

References: DeepKeys, Keys, IsObject, DeepGet

Example

 interface Props {
   a: {
     d: () => void
   }
   b: string
   c: boolean
}

 // Expect: (()=> void) | number | string
 type PropValues = DeepGet<Props, 'a.d' | 'b'>