9142 - CheckRepeatedChars

Answer TestCases

判断一个 string 类型中是否有相同的字符

type CheckRepeatedChars<'abc'>   // false
type CheckRepeatedChars<'aba'>   // true

Solution

type CheckRepeatedChars<T extends string> = T extends `${infer F}${infer E}`
  ? E extends `${string}${F}${string}`
    ? true
    : CheckRepeatedChars<E>
  : false