Injection with @Inject and Injection Tokens

6.5 Injection with @Inject and Injection Tokens

Use @Inject when type information is insufficient, typically with tokens.

import { InjectionToken, Inject } from "@angular/core";

export const API_URL = new InjectionToken<string>("API_URL");

@Injectable({ providedIn: "root" })
export class ApiService {
  constructor(@Inject(API_URL) private url: string) {}
}

Note: Angular 21 supports InjectionTokens for standalone components and services.