Typescript 中的常量枚举
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const enum in Typescript
提问by addam
I have a React application that is using Typescript. Right now I'm running into an issue with const enum. Here's my enum:
我有一个使用 Typescript 的 React 应用程序。现在我遇到了 const 枚举的问题。这是我的枚举：
export const enum Snack {
Apple = 0,
Banana = 1,
Orange = 2,
Other = 3
}
The service I'm trying to match up to isn't returning the value, but the index of the item within the enum. So, for instance, if the user is set to snack on an apple, the service is returning a 0 for that user instead of 'Apple'. Ideally, I'd like to do something like:
我试图匹配的服务不是返回值，而是枚举中项目的索引。因此，例如，如果用户设置为吃苹果零食，则该服务将为该用户返回 0 而不是“Apple”。理想情况下，我想做类似的事情：
var snackIndex = UserSnack.type; // returning 0 in this example
var userSnack = Snack[snackIndex]; // would return 'Apple'
When I try something similar I'm getting the following error:
当我尝试类似的东西时，我收到以下错误：
error TS2476: A const enum member can only be accessed using a string literal.
错误 TS2476：只能使用字符串文字访问 const 枚举成员。
Since the service I'm receiving the data from doesn't return the string, I'm having issues getting this working.
由于我从中接收数据的服务不返回字符串，因此我在使其正常工作时遇到了问题。
Any help is appreciated.
任何帮助表示赞赏。
回答by Ryan Cavanaugh
constin an enum means the enum is fully erased, which means you can't index it by an arbitrary value. Just remove the constmodifier.
const在枚举中意味着枚举被完全擦除，这意味着您不能通过任意值对其进行索引。只需删除const修改器。
See also How do the different enum variants work in TypeScript?
