TypeScript Deep Partial Interface

readme.md

TypeScript Deep Partial Interface

export type DeepPartial<T> = T extends Function ? T : (T extends object ? { [P in keyof T]?: DeepPartial<T[P]>; } : T);

Before typescript@3.1

type DeepPartial<T> = {
  [P in keyof T]?: T[P] extends Array<infer U>
    ? Array<DeepPartial<U>>
    : T[P] extends ReadonlyArray<infer U>
      ? ReadonlyArray<DeepPartial<U>>
      : DeepPartial<T[P]>
};

---

• 25/12/2018, updated by: https://stackoverflow.com/a/49936686/2500707
• 18/04/2020, updated by:
  • https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#typescript-29
  • https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-1.html#mapped-types-on-tuples-and-arrays

For me, I need that Partial<T[K]> instead of T

export type DeepPartial<T> = {
  [K in keyof T]?: T[K] extends Record<string, unknown> ? DeepPartial<T[K]> : Partial<T[K]>
}