在 Angular 应用程序的编译中找不到声明的 InjectionToken

Question

我正在尝试通过使用 InjectionToken 来提供依赖于用户的网络浏览器的全局配置。但是，在编译应用程序时，在源代码中找不到声明的常量。我之前已经看到这种模式有效（1），但我不确定我在做什么不同。下面是我的代码摘要。

// ./services/system/masks.service

export declare const NUMBER_MASK: InjectionToken<string>;

export function NumberMaskFactory(): NumberMask {
    const lang = navigator.language.substring(0, 2);
    if (lang == "en") {
        const radix: string = getLocaleNumberSymbol(navigator.language, NumberSymbol.Decimal);
        const thousandSeperator: string = getLocaleNumberSymbol(navigator.language, NumberSymbol.Group);

        return new NumberMask(radix, thousandSeperator);
    }
    return new NumberMask(".", ",");
}


export class NumberMask {
    public radix: string;
    public thousandSeparator: string;
    constructor(radix: string, thousandSeparator: string) {
        this.radix = radix;
        this.thousandSeparator = thousandSeparator;
    }
}

// app.module.ts
import { NumberMaskFactory, NUMBER_MASK } from "./services/system/masks.service";
// ...
providers: [
        {
            provide: NUMBER_MASK,
            useFactory: NumberMaskFactory

        }
// ...

编译时抛出以下错误：

./src/app/app.module.ts:112:21-32 - Error: export 'NUMBER_MASK' (imported as 'NUMBER_MASK') was not found in './services/system/masks.service' (possible exports: NumberMask, NumberMaskFactory)

(注1)例如MSAL_INSTANCE在这个sample.

Answer 1

要创建注入令牌，您必须实例化

 export const NUMBER_MASK = new InjectionToken<string>('');

在 Angular 应用程序的编译中找不到声明的 InjectionToken

Declared InjectionToken cannot be found on compile of Angular application

dependency-injection

angular