Angular 提供了根和根模式

Question

Hi what is the difference between Angular's providedIn: root at service level and using the forRoot() module pattern? I have already seen this answer Angular service providedIn VS forRoot which says there is no difference.

1. Does this stand true even if we are creating a library which gives a service?
2. Why do we need to use forRoot pattern with router module then? Why isn't router service provided in root? Any compatibility related reason?

Answer 1

The preferred way to provide a service in a module, do it inside the service,

@Injectable({ providedIn: 'any', })

With providedIn: 'any', all eagerly loaded modules share a singleton instance; however, lazy loaded modules each get their own unique instance

OR

u can choose the following way:

providedIn: YourModule

into your service