Generate Dot-Notation Key Paths for Nested Types in TypeScript

DeepKeys.ts

type Increment<N extends number, Arr extends any[] = []> = Arr['length'] extends N
  ? [...Arr, any]['length']
  : Increment<N, [...Arr, any]>;

type FilteredKeys<T> = Exclude<keyof T, keyof any[]>; 

type DeepKeysPrefix<T, K extends keyof T, MaxDepth extends number, Depth extends number> = Depth extends MaxDepth
  ? never
  : K extends string | number
    ? `${K}.${DeepKeys<T[K], MaxDepth, Increment<Depth>> & string}`
    : never;

export type DeepKeys<T, MaxDepth extends number = 4, Depth extends number = 0> = Depth extends MaxDepth
  ? never
  : T extends Record<string | number, any>
    ? FilteredKeys<T> extends infer K
      ? K extends string | number
        ? K | DeepKeysPrefix<T, K, MaxDepth, Increment<Depth>>
        : never
      : never
    : never;