Angular Interview Questions

The architecture of an Angular application is designed to be modular, scalable, and maintainable, facilitating the development of complex, high-performance web applications. Here are the key components and concepts that define Angular’s architecture:

1. Modules (NgModules):

• Definition: Angular applications are modular, and NgModules are the fundamental building blocks. They help organize an application into cohesive blocks of functionality.
• Purpose: Modules group related code, making it easier to manage and maintain.
• Structure: Each Angular app has a root module (AppModule), with additional feature modules as needed (e.g., SharedModule, UserModule).

2. Components:

• Definition: Components are the primary building blocks of an Angular application.
• Purpose: Each component encapsulates a portion of the user interface, along with its associated logic and data.
• Structure: A component consists of a TypeScript class, an HTML template, and optional CSS styles. The class handles data and logic, the template defines the view, and the styles apply design.

3. Templates:

• Definition: Templates define the view for a component.
• Purpose: They use Angular’s declarative syntax to bind data and handle user events.
• Structure: Templates are written in HTML and can include Angular-specific syntax for data binding, loops, and conditionals (e.g., *ngIf, *ngFor, {{ }} for interpolation).

4. Metadata:

• Definition: Metadata is used to decorate classes and configure how Angular processes them.
• Purpose: Decorators like @Component and @NgModule provide this configuration.
• Structure: Metadata is added using decorators on classes to specify details about components and modules.

5. Services:

• Definition: Services are classes that handle business logic and data retrieval.
• Purpose: They promote code reuse and separation of concerns by encapsulating non-UI logic.
• Structure: Services are typically injected into components or other services using Angular’s dependency injection (DI) system.

6. Dependency Injection (DI):

• Definition: DI is a design pattern used to supply a component or service with its dependencies.
• Purpose: Angular’s DI system makes it easy to manage dependencies, improving code organization and testability.
• Structure: Dependencies are declared in the constructor of a class and provided by Angular’s injector.

7. Directives:

• Definition: Directives are classes that add behavior to elements in Angular applications.
• Purpose: They extend HTML by allowing custom elements and attributes.
• Types:
  • Component Directives: Define custom elements (@Component).
  • Structural Directives: Alter the DOM layout (e.g., *ngIf, *ngFor).
  • Attribute Directives: Change the appearance or behavior of an element (e.g., ngClass, ngStyle).

8. Pipes:

• Definition: Pipes are simple functions that transform data in templates.
• Purpose: They format and transform data displayed in the view.
• Structure: Angular provides built-in pipes (e.g., date, uppercase) and allows for custom pipe creation.

9. Routing:

• Definition: Angular’s router module enables navigation between views or components.
• Purpose: It manages application navigation and URL manipulation.
• Structure: Routes are defined in a routing module, mapping paths to components.

10. Forms:

• Definition: Angular supports building and managing forms efficiently.
• Purpose: Forms handle user input and validation.
• Types:
  • Template-Driven Forms: Suitable for simple forms, defined in the template.
  • Reactive Forms: Suitable for complex forms, defined in the component class.

Application Flow:

1. Bootstrap: The Angular application starts by bootstrapping the root module (AppModule).
2. Modules: The root module loads and configures components, services, and other modules.
3. Components: Components render views and handle user interactions.
4. Services and DI: Services provide data and logic, injected where needed.
5. Routing: The router manages navigation and displays the appropriate components based on the URL.
6. Data Binding: Templates bind data from the component to the view, ensuring synchronization.
7. Directives and Pipes: Enhance templates by manipulating the DOM and transforming data.

This architecture ensures Angular applications are organized, maintainable, and scalable, making it suitable for projects of any size.