TypeScript：將鍵值類型反向映射到值鍵

Question

給定一個類型的對象：

type Key2Value = {
  foo: "bar"
  voo: "doo"
}

假設該類型的值始終是字符串類型，那么如何構造一個實用程序類型ReverseMap<T>將鍵值對反向映射到值鍵對？

type Value2Key = ReverseMap<Key2Value>
// yields:
type Value2Key = {
  bar: "foo"
  doo: "voo"
}

Answer 1

type Key2Value = {
  foo: "bar"
  voo: "doo"
}

type ReverseMap<T extends Record<keyof T, keyof any>> = {
    [P in T[keyof T]]: {
        [K in keyof T]: T[K] extends P ? K : never
    }[keyof T]
}

type Value2Key = ReverseMap<Key2Value>

操場