打字稿：如何在类型参数中定义可能的键数组？

Question

我的计划是：

 enum hobbies { music = 'music', sports = 'sports' } type Hobbies <T extends Array<keyof typeof hobbies>> = { [key in T]: number } type Musician = { hobbies: Hobbies<["music"]> } type Racer = { hobbies: Hobbies<["racing"]> //errors, fine } const musician: Musician = { hobbies: { music: 2, racing: 1 //should error but it doesn't } }

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问题是它实际上确实会抛出错误，但它对key in T会抛出错误，而且它是无效的。

所以如果我用 hobbies.racing 定义 Musician 就不会出错

有什么解决方案吗？

Answer 1

没有严格回答这个问题，但你可以使用联合类型而不是数组：

enum hobbies {
  music = 'music',
  sports = 'sports'
}

type Hobbies <T extends keyof typeof hobbies> = {
  [key in T]: number
}

type Musician = {
  hobbies: Hobbies<"music">
}

type Racer = {
  hobbies: Hobbies<"racing"> //errors, fine
}

const musician: Musician = {
  hobbies: {
    music: 2,
    racing: 1 //now errors
  }
}

要指定多个允许的键，只需使用联合类型：

hobbies: Hobbies<"music" | "sports">

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---

要回答原始问题并使数组工作：

type Hobbies <T extends Array<keyof typeof hobbies>> = {
  [key in T[number]]: number
}

注意key in T[number]中的键 - 键在数组值中

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