TS体操--DeepReadonly

[lhp96]

type X = {
  a: () => 22
  b: string
  c: {
    d: boolean
    e: {
      g: {
        h: {
          i: true
          j: 'string'
        }
        k: 'hello'
      }
      l: [
        'hi',
        {
          m: ['hey']
        },
      ]
    }
  }
}

type Expected = {
  readonly a: () => 22
  readonly b: string
  readonly c: {
    readonly d: boolean
    readonly e: {
      readonly g: {
        readonly h: {
          readonly i: true
          readonly j: 'string'
        }
        readonly k: 'hello'
      }
      readonly l: readonly [
        'hi',
        {
          readonly m: readonly ['hey']
        },
      ]
    }
  }
}

// Your Answer
type DeepReadonly<T> = {
  +readonly [P in keyof T]: keyof T[P] extends never ? T[P] : DeepReadonly<T[P]>
}

// keyof T[P]，看是否有对象的键

[gswysy]

type DeepReadonly<T> = {
    readonly [p in keyof T] : T[p] extends object ? DeepReadonly<T[p]> : T[p]
}