typescript 类型练习之递归

数组类型的递归

type DeepPromiseValueType<P extends Promise<unknown>> = 
  P extends Promise<infer ValueType> 
   ? ValueType extends Promise<unknown>
     ? DeepPromiseValueType<ValueType>
     : ValueType
    : never

type res1 = DeepPromiseValueType<Promise<Promise<Promise<Record<string, any>>>>>


type DeepPromiseValueType2<T> = 
  T extends Promise<infer ValueType>
    ? DeepPromiseValueType2<ValueType>
    : T;

type res2 = DeepPromiseValueType2<Promise<Promise<number>>>

type res3 = Record<string, any>

type ReverseArr<Arr extends unknown[]> = 
  Arr extends [infer First, ...infer Rest]
    ? [...ReverseArr<Rest>, First]
    : Arr;

type res4 = ReverseArr<[1,2,3,4,5]>


type IsEqual<A, B> = (A extends B ? true : false) & (B extends A ? true : false)

type Includes<Arr extends unknown[], FindItem> = 
  Arr extends [infer First, ...infer Rest]
    ? IsEqual<First, FindItem> extends true
        ? true
        : Includes<Rest, FindItem>
    : false;

type res5 = Includes<[1, 2, 3, 44, 5, {a: 11, b: 2}], {a: 11}>



type BuildArray<
    Length extends number,
    Ele = unknown,
    Arr extends unknown[] = []
> = Arr['length'] extends Length
 ? Arr : BuildArray<Length, Ele, [...Arr, Ele]>

 type res6 = BuildArray<3>

 // 字符串

type ReplaceStr<
    Str extends string,
    From extends string,
    To extends string,
> = Str extends `${infer Prefix}${From}${infer Suffix}`
  ? `${Prefix}${To}${Suffix}` : Str;


type ReplaceAll<
    Str extends string,
    From extends string,
    To extends string
> = Str extends `${infer Left}${From}${infer Right}`
   ? `${Left}${To}${ReplaceAll<Right, From, To>}`
  : Str;