angular-di

Angular dependency injection with inject() replaces constructor parameters by allowing you to obtain dependencies directly within class properties or functions. This approach enables seamless dependency access without constructors and integrates cleanly with DestroyRef for lifecycle cleanup.

Hierarchical injection differentiates providers and viewProviders by dependency visibility. Providers configure dependency scopes available to the component and its content children, while viewProviders restrict visibility to the component's own view children, affecting dynamic provider resolution.

Injection Tokens are needed in Angular when providing non-class dependencies, configuring multi-provider patterns, or differentiating environment and platform-aware providers. They act as keys for token-driven provider configuration, enabling flexible APIs and robust testing utilities with mock overrides.

Configuring provider scopes involves registering dependencies at the root level for application-wide singletons, component level for restricted instances, or route level for route-specific services. This provider configuration ensures scalable front-end architectures across components, services, and routes.

Angular dependency injection supports robust testing utilities by allowing mock overrides and environment or platform-aware provider configurations. You can replace tokens with test stubs using provider configuration, ensuring explicit DI usage and isolated component testing.