Typescript类型体操 - String to Union

题目

中文

实现一个将接收到的 String 参数转换为一个字母 Union 的类型。

例如

type Test = '123';
type Result = StringToUnion<Test>; // expected to be "1" | "2" | "3"

English

Implement the String to Union type. Type take string argument. The output should be a union of input letters

For example

type Test = '123';
type Result = StringToUnion<Test>; // expected to be "1" | "2" | "3"

答案

type StringToUnion<T extends string> = T extends `${infer L}${infer R}`
  ? L | StringToUnion<R>
  : never;

在线演示

标签：Typescript,String,Union,Test,StringToUnion,type,infer
来源： https://www.cnblogs.com/laggage/p/type-challenge-string-to-union.html