Typescript - 如何正確合並兩個包含重疊的枚舉？

Question

給定以下枚舉：

enum MyFirstEnum {
  A = 'A',
  B = 'B',
  C = 'C'
}

enum MySecondEnum {
  C = 'C',
  D = 'D',
  E = 'E'
}

合並它們的正確方法是什么？ 請注意，它們在鍵C = 'C'中包含重疊，所以只是MyFirstEnum | MySecondEnum MyFirstEnum | MySecondEnum可能會引起一些麻煩，例如：

type BothEnums = MyFirstEnum | MySecondEnum

const myRecord: Partial<Record<BothEnums, string>> = {}
const someKey = MyFirstEnum.C

myRecord[someKey] = 'some value' // ❌ Property '[MyFirstEnum.C]' does not exist on type 'Partial<Record<BothEnums, string>>'

如果我從這個問題How to merge two enums in TypeScript 中理解正確， Typescript 不能很好地處理具有重復鍵和值的不同枚舉。

但是，如果真的需要將枚舉與這種重疊合並，如何在沒有（或更少）進一步問題的情況下做到這一點？

Answer 1

那行得通嗎？

type BothEnums = {[key in keyof typeof MyFirstEnum | keyof typeof MySecondEnum] : 
  key extends keyof typeof MyFirstEnum ? key extends keyof typeof MySecondEnum ? (typeof MySecondEnum[key]  | typeof MyFirstEnum[key]) :
    typeof MyFirstEnum[key] : key extends keyof typeof MySecondEnum ? typeof MySecondEnum[key] : never} 

相當於：

type BothEnums = {
    A: MyFirstEnum.A;
    B: MyFirstEnum.B;
    C: MyFirstEnum.C | MySecondEnum.C;
    D: MySecondEnum.D;
    E: MySecondEnum.E;
}

需要用 keyof 調用：

const myRecord: Partial<Record<keyof BothEnums, string>> = {}
const someKey1 = MyFirstEnum.C
const someKey2 = MySecondEnum.C

myRecord[someKey1] = 'some value 1' 
myRecord[someKey2] = 'some value 2' 

console.log(JSON.stringify(myRecord)) // "{"C":"some value 2"}" 

但我個人更喜歡這個選項：

const MyFirstEnumDef = ['A','B','C'] as const satisfies readonly string[];
const MySecondEnumDef = ['C','D','E'] as const satisfies readonly string[];
type MyFirstEnum = typeof MyFirstEnumDef[number]
type MySecondEnum = typeof MySecondEnumDef[number]

type BothEnums = MyFirstEnum | MySecondEnum


const myRecord: Partial<Record<BothEnums, string>> = {}
const someKey1 = "C"
myRecord[someKey1] = 'some value 1' 

console.log(JSON.stringify(myRecord)) // "{"C":"some value 1"}"