Understanding the lifecycle of an Angular service is crucial for effectively managing dependencies and ensuring optimal performance in your application. Here’s a breakdown of the lifecycle of an Angular service:
1. CreationWhen a service is first requested by a component, directive, or another service, Angular’s dependency injection system creates an instance of the service. This happens only once if the service is provided at the root level or a module level, ensuring a singleton instance.
Hierarchical Dependency Injection (DI) in Angular is a powerful feature that allows you to control the scope and lifetime of services. It enables you to create a hierarchy of injectors, where each injector can provide its own set of dependencies. This hierarchy mirrors the component tree, allowing for fine-grained control over which services are available to which parts of your application.
In Angular, every component has its own injector, and these injectors form a hierarchy. The root injector is created when the application starts, and child injectors are created for each component. When a component requests a dependency, Angular starts at the component’s injector and works its way up the hierarchy until it finds a provider for the requested dependency.
The providedIn property is used within the @Injectable decorator to specify where the service should be provided. This is a more modern and preferred way to provide services in Angular.
Global Scope: When you use providedIn: 'root', the service is registered with the root injector, making it a singleton and available throughout the entire application.
In Angular, providers are a fundamental concept that allows you to inject dependencies into your components, services, and other parts of your application. They play a crucial role in Angular's dependency injection (DI) system, making it easier to manage and share services across your application.
A provider is an instruction to the Angular dependency injection system on how to obtain a value for a dependency. When you configure a provider, you tell Angular how to create an instance of a service or value that can be injected into components, directives, pipes, or other services.
Dependency Injection (DI) is a design pattern used to implement IoC (Inversion of Control), allowing a class to receive its dependencies from an external source rather than creating them itself. Angular’s DI system is a powerful feature that makes it easy to manage dependencies and promote code reusability and testability.
In Angular, DI is used to provide components, services, and other classes with the dependencies they need. The Angular injector is responsible for creating and managing these dependencies. Here’s a step-by-step explanation of how DI works in Angular:
In Angular, decorators are used to attach metadata to classes, methods, properties, and parameters. Two commonly used decorators are @Injectable and @Inject. While they might seem similar, they serve different purposes. Let’s dive into their differences and see how they are used with examples.
The @Injectable decorator is used to mark a class as available for dependency injection. It tells Angular's dependency injection system that the class can be injected as a dependency into other classes.
