Type Challenges: 01367-medium-remove-index-signature Solution

type RemoveIndexSignature<T> = {
  [K in keyof T as {} extends Record<K, true> ? never : K]: T[K]
}

Solution by MohammadArasteh #35272

// your answers
type RemoveIndexSignature<T> = {
  [key in keyof T as string extends key 
    ? never 
    : number extends key 
      ? never 
      : symbol extends key ? never : key]: T[key];

Solution by AndreGeng #34753

type RemoveIndexSignature<T, P = PropertyKey> = {
  [K in keyof T as P extends K ? never : (K extends P ? K : never)]: T[K]
}

Solution by devshinthant #34627

/**
 * 
 * 主要是把： 
 * - [key: string]:any
 * - [key: number]:any
 * - [key: symbol]:any
 * 筛选掉
 * 用 keyof 遍历这几个属性时，结果分别是：
 * string
 * number
 * symbol
 */

type RemoveIndexSignature<T> = {
  [k in keyof T 
  as string extends k ? never :
  number extends k ? never :
  symbol extends k ? never : k]
  : T[k]
}

Solution by Jayce-liang #34625

type RemoveIndexSignature<T> = {
  [K in keyof T as string extends K ? never : number extends K ? never : symbol extends K ? never : K]: T[K]
}

Solution by ouzexi #34042

// your answers
type IsIndexSignature<T, K = PropertyKey> = T extends T ? K extends T ? 1 : 2 : never
type RemoveIndexSignature<T> = {
  [P in keyof T as IsIndexSignature<P> extends 2 ? P : never]: T[P]
}

Solution by heyuelan #33684

type RemoveIndexSignature<T, L = string | number | symbol> = {
  [K in keyof T as (L extends K ? 0 : 1) extends 1 ? K : never]: T[K]
}

Solution by all-user #33116

// your answers
type RemoveIndexSignature<T> = {
  [key in keyof T as Extract<PropertyKey,key> extends never  ? key: never] : T[key]
}

Solution by sciencefunq #32910

// your answers
type RemoveIndexSignature<T, P = PropertyKey> = {
[key in keyof T as P extends key ? never : key extends P ? key : never]: T[key]
}

Solution by pea-sys #32703

type RemoveIndexSignature<T, P = PropertyKey> = {
  [K in keyof T as K extends P ? (P extends K ? never : K) : never]: T[K];
};

Solution by jinyoung234 #32475

type RemoveIndexSignature<T, P=PropertyKey> = {
  [K in keyof T as P extends K ? never : K extends P ? K : never]: T[K]
}

배운것

PropertyKey 라는 타입이 따로 존재하는 것을 알았다 (= keyof any)
P를 이용하여 T에서 뽑아낸 K를 검사해 인덱스 시그니처 제거 후 K 가 P 제약 조건을 만족하는지 검사하여 T[K]를 만들어냈다.
as 활용법

Solution by dev-hobin #32442

type RemoveIndexSignature<T, P = string | number | symbol> = {
  [K in keyof T as (
    K extends P 
      ? P extends K 
        ? never
        : K 
      : never
  )]: T[K]
}

Solution by SazonovV #31334

// your answers
type RemoveIndexSignature<T> = {
  [K in keyof T as string extends K 
    ? never 
    : number extends K 
      ? never 
      : symbol extends K
        ? never
        : K
  ]: T[K]
};

Solution by d1zzzzy #31266

// your answers
type RemoveIndexSignature<T> = {[K in keyof T as number extends K?never: string extends K?never:symbol extends K?never:K]:T[K]}

Solution by kangaroona #31018

type IsEqual<T, U> = (<P>() => P extends T ? 1 : 2) extends (<P>() => P extends U ? 1 : 2) ? true : false

type IndexSignatureType<T> = IsEqual<T, string> | IsEqual<T, number> | IsEqual<T, symbol>

type IsIndexSignature<T> = T extends true ? true : never

type RemoveIndexSignature<T> = {
    [P in keyof T as [IsIndexSignature<IndexSignatureType<P>>] extends [never] ? P : never]: T[P]
}

Solution by Yirujet #29821

type RemoveIndexSignature<T> = { [Key in keyof T as string extends Key ? never : number extends Key ? never : symbol extends Key ? never : Key]: T[Key] }

Solution by hajeonghun #28868

type RemoveIndexSignature<T,Key=PropertyKey> = { [K in keyof T as Key extends K?never:K extends Key?K:never]:T[K] };

Solution by DoubleWoodLin #28657

type RemoveIndexSignature<T> = {
  [
    K in keyof T as number extends K ? never : 
    string extends K ? never : 
    symbol extends K ? never : 
    K
  ]: T[K] 
}

Solution by jjswifty #27580

type RemoveIndexSignature<T> = { [k in keyof T as string extends k ? never : number extends k? never : symbol extends k ? never : k]: T[k] }

Solution by smileboyi #26869

type RemoveIndexSignature<T, P = PropertyKey> = {
[key in keyof T as P extends key ? never : key extends P ? key : never]: T[key]
}

Solution by AwesomeYelim #26861

type RemoveIndexSignature<T> = {
  [P in keyof T as string extends P ? never : number extends P ? never : symbol extends P ? never : P]: T[P]
}```

Solution by 8471919 #26800

type RemoveIndexSignature<T extends {}> = {
  [K in keyof T as K extends `${infer R}` ? R : never]: T[K];
};

Solution by ryuji-1to #26742

type RemoveIndexSignature<T, P=PropertyKey> = {
  [K in keyof T as P extends K? never : K extends P ? K : never]: T[K]
}

Solution by kakasoo #26361

// your answers
type RemoveIndexSignature<T> = {
  [K in keyof T as (PropertyKey extends keyof T[K] ? never : K)]: T[K];
};

Solution by CheolMinBae #25515

type RemoveIndexSignature<T> = { [P in keyof T as string extends P ? never : number extends P ? never : symbol extends P ? never : P]: T[P] }

Solution by jsujeong #25514

// your answers
type RemoveIndexSignature<T> = {
  [key in keyof T as number extends key ? never : string extends key ? never : symbol extends key ? never : key]: T[key]
};

Solution by rayjayjin #25465

// your answers

type RemoveIndexSignature<T> = {
  [Key in keyof T as ( string extends Key ? never : number extends Key ? never : symbol extends Key ? never : Key)]: T[Key]
}

Solution by hhk9292 #25345

type CheckIndexSignature<V, T = PropertyKey> = T extends V ? true : false
type RemoveIndexSignature<T extends Record<PropertyKey, unknown>>
  = {
      [
        Key in keyof T
          // as string extends Key ? never
          //   : number extends Key ? never
          //   : symbol extends Key ? never
          //   : Key
          as CheckIndexSignature<Key> extends false ? Key : never
      ]: T[Key]
    }

Solution by tokyo9pm #25248

'a' extends string 이면 string extends 'a'는 아니라는 점을 이용. key는 string, number, symbol 이어야 한다.



type RemoveIndexSignature<T> = {
  [K in keyof T as string extends K ? never: number extends K ? never: symbol extends K ? never: K]: T[K]
}

Solution by isntkyu #25150

type RemoveIndexSignature<T, P = PropertyKey> = {
  [
    K in keyof T as P extends K
      ? never 
      : K extends P ? K : never
  ]: T[K]
}

// type PropertyKey = string | number | symbol

P extends K ? to filter out index signatures [key: string] [key: symbol]

Solution by se030 #24551