我想迭代一个TypeScript枚举对象,并获得每个枚举符号名称,例如: enum myEnum {entry1, entry2}
for (var entry in myEnum) {
// use entry's name here, e.g., "entry1"
}
我想迭代一个TypeScript枚举对象,并获得每个枚举符号名称,例如: enum myEnum {entry1, entry2}
for (var entry in myEnum) {
// use entry's name here, e.g., "entry1"
}
当前回答
他们在官方文件中提供了一个叫做“反向映射”的概念。它帮助了我:
https://www.typescriptlang.org/docs/handbook/enums.html#reverse-mappings
解决方法很简单:
enum Enum {
A,
}
let a = Enum.A;
let nameOfA = Enum[a]; // "A"
其他回答
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。
你可以用下面的方法从Enum中获取一个名称数组:
const enumNames: string[] = Object.keys(YourEnum).filter(key => isNaN(Number(key)));
基于上面的一些回答,我提出了这个类型安全的函数签名:
export function getStringValuesFromEnum<T>(myEnum: T): (keyof T)[] {
return Object.keys(myEnum).filter(k => typeof (myEnum as any)[k] === 'number') as any;
}
用法:
enum myEnum { entry1, entry2 };
const stringVals = getStringValuesFromEnum(myEnum);
stringVals的类型是'entry1' | 'entry2'
看看它的实际应用
可以是简短的:
enum AnimalEnum {
DOG = "dog",
CAT = "cat",
MOUSE = "mouse"
}
Object.keys(AnimalEnum).filter(v => typeof v == 'string' && isNaN(v))
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})