What is the purpose of providedIn with the Injectable decorator when generating Services in Angular 6?

Question

When generating services in the Angular CLI, it is adding extra metadata with a \'provided in\' property with a default of \'root\' for the Injectable decorator.

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Answer 1

if you use providedIn, the injectable is registered as a provider of the Module without adding it to the providers of the module.

From Docs

The service itself is a class that the CLI generated and that's decorated with @Injectable. By default, this decorator is configured with a providedIn property, which creates a provider for the service. In this case, providedIn: 'root' specifies that the service should be provided in the root injector.