Dependency injection

Dependency injection is one of the cornerstones of the Angular framework. Angular relies on the dependency injection design pattern to manage the relationships and interactions between different elements within an application. When using dependency injection, there are two main roles: the providers and consumers of the dependencies. As such, Angular dependency injection lets you provide logic or data to sections of your application that need to consume the given logic or data. Dependency injection is vital for developing loosely coupled applications with more modular, testable, and maintainable code. Generally speaking, dependencies in an Angular application are services (classes decorated with the @Injectable() decorator), but they can be strings, functions, or anything else you want to provide throughout your application.

The Injector abstraction is the core element of the Angular dependency injection system and facilitates the connection between providers...