手动实现 DeepReadonly

Question

type DeepReadonly<T> = {
  readonly [K in keyof T]: keyof T[K] extends never ? T[K] : DeepReadonly<T[K]>;
};

type X = {
  a: () => 22;
  b: string;
  c: {
    d: boolean;
  };
};

type ReadonlyX = DeepReadonly<X>;

let a: ReadonlyX = {
  a: () => 22,
  b: "11",
  c: {
    d: true,
  },
};


a.b = '22'