Chapter 7. Services, Dependency Injection, and NgModule
This chapter will cover the following recipes:
- Injecting a simple service into a component
- Controlling service instance creation and injection with NgModule
- Service injection aliasing with useClass and useExisting
- Injecting a value as a service with useValue and OpaqueTokens
- Building a provider-configured service with useFactory
Introduction
Angular 1 gave you a hodgepodge of different service types. Many of them had a great deal of overlap. Many of them were confusing. And all of them were singletons.
Angular 2 has totally thrown away this concept. In its place, there is a shiny new dependency injection system that is far more extensible and sensible than its predecessor. It allows you to have atomic ...
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