Lazy loading is a design pattern in Angular that allows you to load modules only when they are needed, rather than loading all modules upfront. This can significantly improve the performance of your application by reducing the initial load time.
A lazy-loaded module is an Angular module that is loaded on demand. Instead of being included in the main bundle, it is loaded asynchronously when the user navigates to a route that requires the module.
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.
The Visitor Pattern is a behavioral design pattern that allows you to add further operations to objects without having to modify them. It is particularly useful when you have a structure of objects and you want to perform operations on these objects that can be defined outside of their classes. This pattern follows the Open/Closed Principle by allowing new functionality to be added without altering the existing code.
The Visitor Design Pattern should be used when you have distinct and unrelated operations to perform across a structure of objects (element objects). That means the Visitor Design is used to create and perform new operations on a set of objects without changing the object structure or classes.
The State Design Pattern is a behavioral design pattern that allows an object to alter its behavior when its internal state changes. This pattern is particularly useful for implementing state machines and ensuring that the object’s behavior remains manageable and modular.
This pattern is useful when an object needs to go through several states, and its behavior differs for each state. Instead of having conditional statements throughout a class to handle state-specific behaviors, the State Design Pattern delegates this responsibility to individual state classes.
