Google created the popular front-end framework Angular to help developers create dynamic, contemporary online apps. Angular makes complicated web development chores easier with its component-based architecture, two-way data binding, and strong features like dependency injection and reactive forms.

Understanding important Angular principles is crucial for engineers getting ready for an interview or hiring managers evaluating applicants. In addition to scenario-based questions that assess practical problem-solving abilities, this blog offers 15 comprehensive Angular interview questions that span basic, intermediate, and advanced subjects.

1. What is Angular?

Angular is an open-source, TypeScript-based framework developed by Google for building single-page applications (SPAs). It enables programmers to use a component-based design to create dynamic, high-performing online applications. Angular improves user experience and speed by allowing smooth navigation without requiring a full page reload, in contrast to typical multi-page apps.

2. What are the key features of Angular?

Angular provides several powerful features that make web development easier and more efficient. Some of its key features include:

• Component-based architecture: Angular applications are built using reusable components that encapsulate UI and logic.

• Two-way data binding: Synchronizes data between the model and the view, reducing the need for manual DOM manipulation.

• Dependency Injection (DI): Allows components to request dependencies rather than creating them, improving modularity and testability.

• Directives: Special markers on DOM elements that modify behavior, such as *ngIf for conditional rendering.

• Routing and navigation: Angular includes a powerful built-in routing system for managing navigation within SPAs.

• HTTP services: Provides built-in support for making HTTP requests to interact with backend APIs.

  
  

3. What is TypeScript, and why is it used in Angular?

TypeScript is a JavaScript superset that adds sophisticated object-oriented features, interfaces, and static typing. TypeScript is used in the development of Angular because it facilitates the writing of clear, error-free, and maintainable code. Early error detection made possible by static typing lowers runtime errors and enhances code quality. Modern JavaScript capabilities are also supported by TypeScript, which increases the scalability and resilience of Angular apps.

4. What is an Angular component?

A component is the fundamental building block of an Angular application. It consists of three key parts:

• Template (HTML): Defines the structure and layout of the UI.

• Styles (CSS/SCSS): Controls the appearance of the component.

• Class (TypeScript): Contains the logic and functionality of the component.

  
  

Each component is defined using the @Component decorator. The root component of an Angular application is typically AppComponent, which serves as the entry point for rendering the UI.

5. What is a Module in Angular?

An Angular module, defined using @NgModule, is a container for a cohesive block of functionality. It groups related components, directives, pipes, and services together. It combines directives, pipes, services, and related parts into one group. AppModule, which bootstraps the primary application component, is the root module in all Angular applications. Modules facilitate code organization and lazy loading, which enhances efficiency by only loading features when required.

6. What is Dependency Injection (DI) in Angular?

Dependency Injection (DI) is a design pattern where a class does not create its own dependencies instead, it obtains them from an outside source. By enabling services to be injected into components, DI in Angular increases code reusability and testability while also increasing the application's modularity. A service that may be injected into other services or components is defined using the @Injectable decorator.

7. What are Directives in Angular?

Directives are special attributes in Angular that modify the behavior of DOM elements. There are three types of directives:

• Component Directives: These are the most common and include a template, making them reusable UI elements.

  
  

• Structural Directives: These alter the DOM structure, such as ngIf (conditional rendering) and ngFor (looping).

  
  

• Attribute Directives: These modify the appearance of elements, such as ngClass (dynamically applying classes) and ngStyle (dynamically setting styles).

  
  

8. What is the difference between Angular and AngularJS?

The initial version of the framework is called AngularJS (Angular 1), whereas Angular (Angular 2+) is a total redesign. Compared to AngularJS, which depended on controllers and two-way data binding, Angular delivers superior performance, supports mobile development, uses TypeScript, and has a component-based structure.

9. What is the purpose of Angular Pipes?

Pipes in Angular are used to transform data before displaying it in the view. They help format data such as dates, numbers, and strings dynamically. Common built-in pipes include DatePipe, CurrencyPipe, and UpperCasePipe. Developers can also create custom pipes for specific data transformations.

10. What is the difference between Components and Directives?

• Components: Have templates and control sections of the UI.

• Directives: Modify the behavior or appearance of DOM elements without a UI template.

  
  

11. What is Two-Way Data Binding?

Two-way data binding synchronizes data between the model and the view. When a user updates an input field, the underlying model automatically updates, and vice versa. This eliminates the need for manual event handling and improves real-time UI interactions.

12. What is the Purpose of the package.json File in Angular?

The package.json file in an Angular project manages dependencies, including development tools, third-party libraries, and Angular itself. It lists all the required packages along with their versions and helps maintain consistent project dependencies.

13. What is Routing in Angular?

Routing enables navigation between different pages in an Angular application without reloading the page. It is managed using the RouterModule and is defined in the app-routing.module.ts file. Routes are mapped to components, enabling seamless transitions between views.

14. What is Lazy Loading in Angular?

Lazy loading improves application performance by loading feature modules only when needed, rather than including them in the initial bundle. This reduces the initial load time and enhances the user experience, particularly in large applications with multiple modules.

15. What is an Angular Service?

A service in Angular is a reusable class that manages business logic, data sharing, and communication between components. Services are injected into components using dependency injection, making the application more modular and maintainable. They are typically used for handling HTTP requests, data storage, and utility functions.

Conclusion

A strong front-end framework called Angular makes it easier to create dynamic, contemporary online apps. Developers use it because of its component-based architecture, dependency injection, two-way data binding, and integrated features like lazy loading and routing. Comprehending these fundamental Angular ideas is essential for developers getting ready for interviews as well as for companies trying to create scalable apps quickly.

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