Description: The ‘Injectable’ decorator in Angular is a fundamental tool that marks a class as available to be provided and injected as a dependency into other components or services. This decorator allows Angular to manage the creation and lifecycle of instances of the class, facilitating dependency injection. By using ‘Injectable’, developers can define services that can be reused across different parts of the application, thus promoting modularity and separation of concerns. This approach not only improves code organization but also facilitates unit testing, as dependencies can be easily mocked or replaced. In summary, ‘Injectable’ is a key component in Angular’s architecture that enables developers to build more scalable and maintainable applications.
History: The concept of dependency injection became popular in software development starting in the 2000s, with the rise of frameworks that promoted modularity and code reuse. Angular, created by Google and initially released in 2010, adopted this pattern to facilitate dependency management in web applications. With the release of Angular 2 in 2016, the ‘Injectable’ decorator became an integral part of the framework, enhancing how developers could define and use services.
Uses: The ‘Injectable’ decorator is primarily used to define services in Angular that can be injected into components, other services, or directives. This allows developers to create more organized and scalable applications, where dependencies are managed centrally. Additionally, it facilitates the implementation of design patterns such as Singleton, where a single instance of a service can be shared throughout the application.
Examples: A practical example of using ‘Injectable’ is the creation of an authentication service in an Angular application. This service can be marked with the ‘Injectable’ decorator and then injected into components that require access to authentication functionality. Another example is a data management service that can be used by multiple components to access an API, ensuring that all components use the same data access logic.
