Anil Singh | Code-sample.com

What Are @Injectable providers? The @Injectable decorator identifies services and other classes that are intended to be injected. It can also be used to configure a provider for those services. To inject the service into a component, Angular provides an Injector decorator: @Injectable(). A provider defines the set of injectable objects that are available in the injector of this module. The @Injectable decorator marks a class as available to an injector for instantiation. An injector reports an error when trying to instantiate a class that is not marked as @ Injectable . Injectors are also responsible for instantiating components. At the run-time the injectors can read class metadata in the JavaScript code and use the constructor parameter type information to determine what things to inject. Injectable decorator and metadata - @ Injectable ({   providedIn? : Type < any > | 'root' | null   factory : () => any }) To inject the service ...

What Is a Dependency? When module X in an application needs module Y to run, then module Y is a dependency of module X.   What Is Dependency Injection (DI)? Dependency Injection is a powerful pattern for managing code dependencies. DI is a way to create objects that depend upon other objects. Angular has its own DI framework pattern, and you really can't build an Angular application without Dependency injection (DI). A DI system supplies the dependent objects when it creates an instance of an object. Let us take an example of a CAR. The CAR consists of following things - 1.       Wheel 2.       Headlight 3.       Outer door 4.       Inner door 5.       Glass 6.       Window 7.       Fuel level sensor So to complete the CAR, we need those eight and so many things. In this...