我卑微的2美分基于阅读一个了不起的评论从github TS讨论

const EnvironmentVariants = ['development', 'production', 'test'] as const 
type EPredefinedEnvironment = typeof EnvironmentVariants[number]

然后在编译时:

// TS2322: Type '"qaEnv"' is not assignable to type '"development" | "production" | "test"'.
const qaEnv: EPredefinedEnvironment = 'qa' 

在运行时:

function isPredefinedEnvironemt(env: string) {
  for (const predefined of EnvironmentVariants) {
    if (predefined === env) {
      return true
    }
  }
  return false
}

assert(isPredefinedEnvironemet('test'), true)
assert(isPredefinedEnvironemet('qa'), false)

注意，for(const index in environmentvariables){…}将遍历"0"，"1"，"2"集合

老问题了，为什么不使用const对象映射呢?

不要这样做:

enum Foo {
    BAR = 60,
    EVERYTHING_IS_TERRIBLE = 80
}

console.log(Object.keys(Foo))
// -> ["60", "80", "BAR", "EVERYTHING_IS_TERRIBLE"]
console.log(Object.values(Foo))
// -> ["BAR", "EVERYTHING_IS_TERRIBLE", 60, 80]

这样做(注意as const强制转换):

const Foo = {
    BAR: 60,
    EVERYTHING_IS_TERRIBLE: 80
} as const

console.log(Object.keys(Foo))
// -> ["BAR", "EVERYTHING_IS_TERRIBLE"]
console.log(Object.values(Foo))
// -> [60, 80]

如果你想在html中获取名字

对于这个枚举

enum CanadianProvinces {
    AB,
    BC,
    MB,
    NB,
    NL,
    NT,
    NS,
    NU,
    ON,
    PE,
    QC,
    SK,
    YT
}

将组件中的变量赋值为

canadianProvinces = CanadianProvinces 

然后，在你的html

{{canadianProvinces[0]}}

你张贴的代码将工作;它将打印出枚举的所有成员，包括枚举成员的值。例如，以下代码:

enum myEnum { bar, foo }

for (var enumMember in myEnum) {
   console.log("enum member: ", enumMember);
}

将打印以下内容:

Enum member: 0
Enum member: 1
Enum member: bar
Enum member: foo

如果你只想要成员名，而不是值，你可以这样做:

for (var enumMember in myEnum) {
   var isValueProperty = Number(enumMember) >= 0
   if (isValueProperty) {
      console.log("enum member: ", myEnum[enumMember]);
   }
}

只打印出名字:

Enum member: bar  
Enum member: foo

注意:这有点依赖于实现细节:TypeScript将enum编译为JS对象，enum值是对象的成员。如果TS决定在未来以不同的方式实现它们，上述技术可能会中断。

Typescript游乐场示例

enum TransactionStatus {
  SUBMITTED = 'submitted',
  APPROVED = 'approved',
  PAID = 'paid',
  CANCELLED = 'cancelled',
  DECLINED = 'declined',
  PROCESSING = 'processing',
}


let set1 = Object.entries(TransactionStatus).filter(([,value]) => value === TransactionStatus.SUBMITTED || value === TransactionStatus.CANCELLED).map(([key,]) => {
    return key
})


let set2 = Object.entries(TransactionStatus).filter(([,value]) => value === TransactionStatus.PAID || value === TransactionStatus.APPROVED).map(([key,]) => {
    return key
})

let allKeys = Object.keys(TransactionStatus)



console.log({set1,set2,allKeys})

如果它是你的枚举，你定义如下所示，名称和值是相同的，它会直接给你条目的名称。

enum myEnum { 
    entry1="entry1", 
    entry2="entry2"
 }

for (var entry in myEnum) { 
    // use entry's name here, e.g., "entry1"
}