How has Dependency Injection in Angular 2+ evolved from Angular 8 to Angular 17?

I researched this question via Microsoft Copilot with ChatGPT 4.0 activated. Dependency Injection (DI) in Angular has seen several changes and improvements from Angular 8 through Angular 17. Here’s a summary of the evolution:

Angular 8:

• DI was a core feature with providers defined at the module or component level.
• The @Injectable() decorator was used to mark a class as available to an injector for instantiation.
• Hierarchical injection allowed sharing of dependencies at different levels of the application1.

Angular 10:

• No significant changes were noted in DI from Angular 8 to Angular 10 based on the available information.

Angular 12:

• Again, no major updates were highlighted for DI in the transition to Angular 12.

Angular 14:

• Introduced the inject function, allowing for the injection of dependencies without the need to list them in a constructor. This function could be used inside components, directives, and pipes2.
• Allowed the use of @Inject in Directive and Component constructor contexts, improving the injection of non-class-based tokens3.

Angular 16:

• Angular 16 focused on other areas of the framework, and no specific changes to DI were emphasized in the update notes.

Angular 17:

• Brought a new way to do DI using the @Inject decorator and inject function, potentially eliminating the need for a constructor for dependency injection4.
• Emphasized the use of InjectionToken to provide and inject values, which can be useful when injecting values other than classes5.

These changes reflect Angular’s commitment to enhancing the developer experience and optimizing the framework’s performance and flexibility. It’s important to note that while some versions may not have introduced significant changes to DI, the overall evolution shows a trend towards more flexible and modular code. For the most accurate and detailed information, always refer to the official Angular documentation or migration guides for each version.