Suggest an editImprove this articleRefine the answer for “What does the useExisting key do?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**`useExisting`** is a provider key that tells Angular not to create a new service but to use the existing instance of another one. **Key point:** `useExisting` lets two different tokens point to the same service instance.Shown above the full answer for quick recall.Answer (EN)ImageThe `useExisting` key tells Angular: > "Do not create a new service, use the existing instance of another one." --- ### Example: ```ts providers: [ { provide: AuthService, useClass: AuthService }, { provide: LoginService, useExisting: AuthService } ] ``` Now, if something requests `LoginService`, Angular returns **the same object** as `AuthService`. --- ### When this is needed: - when two different tokens must point to the same service; - to avoid duplicating instances or causing conflicts; - to share the same state under different names. --- **Summary:** `useExisting` is a way to tell Angular: *"use the dependency that already exists instead of creating a new one."*For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.