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Absolute

介绍​

实现一个接收string,number或bigInt类型参数的Absolute类型,返回一个正数字符串。

ts
  type Test = -100;
  type Result = Absolute<Test>; // expected to be "100"
ts
  type Test = -100;
  type Result = Absolute<Test>; // expected to be "100"
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起点​

ts
/* _____________ Your Code Here _____________ */
 
type Absolute<T extends number | string | bigint> = any
 
/* _____________ Test Cases _____________ */
 
type cases = [
  Expect<Equal<Absolute<0>, '0'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<-0>, '0'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<10>, '10'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<-5>, '5'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<'0'>, '0'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<'-0'>, '0'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<'10'>, '10'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<'-5'>, '5'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<-1_000_000n>, '1000000'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<9_999n>, '9999'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
]
 
ts
/* _____________ Your Code Here _____________ */
 
type Absolute<T extends number | string | bigint> = any
 
/* _____________ Test Cases _____________ */
 
type cases = [
  Expect<Equal<Absolute<0>, '0'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<-0>, '0'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<10>, '10'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<-5>, '5'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<'0'>, '0'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<'-0'>, '0'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<'10'>, '10'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<'-5'>, '5'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<-1_000_000n>, '1000000'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Absolute<9_999n>, '9999'>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
]
 
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解决方案​

Spoiler warning // Click to reveal answer
ts
// most popular
 
type Absolute<T extends number | string | bigint> = `${T}` extends `-${infer U}` ? U : `${T}`
ts
// most popular
 
type Absolute<T extends number | string | bigint> = `${T}` extends `-${infer U}` ? U : `${T}`
ts
// 没啥用
 
type Absolute<T extends number | string | bigint> =   T extends number 
    ? `${T}` extends `-${infer Tn}` ? `${Tn}` : `${T}`
    : T extends string
      ? `${T}` extends `-${infer Ts}` ? `${Ts}` : `${T}`
      : T extends bigint
        ? `${T}` extends `-${infer Tb}`
          ? `${Tb}`
          : `${T}`
        : never
ts
// 没啥用
 
type Absolute<T extends number | string | bigint> =   T extends number 
    ? `${T}` extends `-${infer Tn}` ? `${Tn}` : `${T}`
    : T extends string
      ? `${T}` extends `-${infer Ts}` ? `${Ts}` : `${T}`
      : T extends bigint
        ? `${T}` extends `-${infer Tb}`
          ? `${Tb}`
          : `${T}`
        : never
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