Typescript 如何将字符串字面量类型转化为，字符串中所有字符的联合类型？

Question

type t1 = 'abc'
type AllCharsInString<T extends string> = ...
type t2 = AllCharsInString<t1> // 期望得到 'a' | 'b' | 'c'

能做到吗？

Answer 1

type AllCharsInString<T extends string> = T extends `${infer F}${infer L}` ? F | AllCharsInString<L> : never