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IsTuple

介绍​

实现类型Zip<T, U>, T和U必须是元组.

ts
type case1 = IsTuple<[number]> // true
type case2 = IsTuple<readonly [number]> // true
type case3 = IsTuple<number[]> // false
ts
type case1 = IsTuple<[number]> // true
type case2 = IsTuple<readonly [number]> // true
type case3 = IsTuple<number[]> // false
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起点​

ts
/* _____________ Your Code Here _____________ */
 
type IsTuple<T> = any
 
/* _____________ Test Cases _____________ */
 
type cases = [
  Expect<Equal<IsTuple<[]>, true>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<IsTuple<[number]>, true>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<IsTuple<readonly [1]>, true>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<IsTuple<{ length: 1 }>, false>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<IsTuple<number[]>, false>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<IsTuple<never>, false>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
]
ts
/* _____________ Your Code Here _____________ */
 
type IsTuple<T> = any
 
/* _____________ Test Cases _____________ */
 
type cases = [
  Expect<Equal<IsTuple<[]>, true>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<IsTuple<[number]>, true>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<IsTuple<readonly [1]>, true>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<IsTuple<{ length: 1 }>, false>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<IsTuple<number[]>, false>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<IsTuple<never>, false>>,
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
 
/**
 * 答案没有处理never的情况, 不过已经很完美了,稍加改动即可.
 */
 
type IsTuple<T> =T extends readonly any[]
  ? number extends T['length']?false:true
  : false
 
 
type IsTuple2<T> = [T] extends [never]
    ? false
    : T extends readonly any[]
      ? number extends T['length'] ? false : true
      : false;
 
ts
// most popular
 
/**
 * 答案没有处理never的情况, 不过已经很完美了,稍加改动即可.
 */
 
type IsTuple<T> =T extends readonly any[]
  ? number extends T['length']?false:true
  : false
 
 
type IsTuple2<T> = [T] extends [never]
    ? false
    : T extends readonly any[]
      ? number extends T['length'] ? false : true
      : false;
 
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