Angular 4 Interview Questions and Answers

Prepare for your Angular 4 interview with this collection of Angular 4 Interview Questions and Answers. Covering fundamental concepts like data binding and components, as well as advanced topics such as dependency injection and routing, these insights will enhance your understanding of Angular development. Whether you’re new to Angular or an experienced developer, this resource aims to sharpen your knowledge, providing confidence and readiness to tackle the diverse challenges that may arise during an Angular 4 interview. Explore more with AngularJs Training in Chennai.

Angular 4 Interview Questions and Answers

Why were client-side frameworks like Angular introduced?

Client-side frameworks like Angular emerged to meet the demands of modern web applications, offering tools for rich user interfaces, single-page applications, modular development, and improved developer productivity. They simplify complexity, enhance user experience, and foster community support.

How does an Angular application work?

Angular applications work by combining components, templates, and services. Components define building blocks, templates create the interface, and services handle logic. Modules structure the app, and Angular manages rendering, user interactions, and dynamic updates. Routing enables seamless navigation between views.

Explain Components, Modules and Services in Angular

In Angular, components serve as building blocks, defining both UI and logic. Modules organize these components, services, and features for a structured application. Services provide reusable code to manage application logic, often handling data and facilitating functionality sharing among components. This modular architecture enhances maintainability and scalability in Angular applications.

Describe the concept of ElementRef in Angular 4.

In Angular 4, ElementRef is a class enabling direct access and manipulation of native DOM elements associated with Angular components. It facilitates interaction with HTML elements but should be used cautiously to avoid bypassing Angular mechanisms, which could impact security and maintainability.

How do you send and set cookies in Angular 4?

In Angular 4, use HttpClient to send requests with cookies by including them in the request headers. Create headers with new HttpHeaders() and set cookies with the ‘Cookie’ property. To set cookies on the client side, use document.cookie with the desired name, value, and optional expiration date.

Differentiate between DOM and BOM.

The DOM (Document Object Model) deals with a document’s structure and content, forming a tree of objects. On the other hand, the BOM (Browser Object Model) handles browser-specific features like managing history and cookies, providing an interface to interact with the browser beyond the document.

Explain the concept of lazy loading.

Lazy loading in web development, seen in frameworks like Angular, delays the loading of specific parts of a web app until users need them. Unlike loading everything at the start, lazy loading improves initial page load times by fetching only essential resources upfront. Additional content is loaded on-demand as users navigate through the app.

Explain the types of data binding.

Angular supports four types of data binding:

• One-Way Binding (Component to View): Updates in the component reflect in the view using Interpolation or Property Binding.
• One-Way Binding (View to Component): User actions trigger changes in the component via Event Binding.
• Two-Way Binding: Allows bidirectional updates between component and view using [(ngModel)] for forms.
• Interpolation: Dynamically displays content in the view by embedding expressions within double curly braces {{ expression }}.

Describe the concept of filters in Angular 4.

In Angular 4, filters are replaced by pipes. Pipes modify data in the template before showing it. For instance, using {{ data | uppercase }} displays the data in uppercase. Pipes can be customized or combined to format and alter data, improving how information appears in the user interface.

What are annotations in Angular ?

In Angular, annotations, identified by the @ symbol, are decorators applied to class declarations. These decorators, such as @Component, provide metadata, configuring components, directives, and services. The details, like selector, template, and styles, specified by these decorators enhance the behavior of the associated class.

What is view encapsulation in Angular?

View encapsulation in Angular refers to the mechanism that encapsulates the styles of a component, preventing them from affecting other parts of the application. Angular provides three view encapsulation modes:

• Emulated (default): Styles are scoped to the component by adding unique attributes to the elements, ensuring encapsulation without relying on shadow DOM.
• None: Styles are global and can affect the entire application. Use with caution, as it may lead to style conflicts.
• Shadow DOM: Utilizes the browser’s native shadow DOM to encapsulate styles, providing true isolation. It requires browser support for shadow DOM.

Developers choose the appropriate encapsulation mode based on their application’s requirements and the level of style isolation needed.

What is Angular CLI?

Angular CLI, or Command Line Interface, is a tool created by the Angular team to simplify Angular application development. It provides commands for tasks like project setup, dependency management, building, testing, and deployment. By automating these common tasks, Angular CLI enhances efficiency, promotes best practices, and facilitates smoother project development.

What are Single Page Applications (SPA)?

Single Page Applications (SPAs) are web apps that operate on a single page, providing a smoother user experience. Rather than loading new pages for each action, SPAs dynamically update content using AJAX requests. This approach, commonly implemented with frameworks like Angular, React, or Vue.js, creates a responsive interface akin to desktop applications.

How are Services used in Angular 4?

In Angular, interpolation ({{ }}) displays dynamic content in the view, while property binding ([ ]) sets the value of an HTML element property. Interpolation is for text content, while property binding is versatile, applying to various element properties and Angular directives.

Why is Angular 4 faster than its previous version?

Angular 4 is faster than its predecessor because:

• Better View Engine: It creates less code, making rendering quicker.
• Improved AOT Compilation: Faster startup times with optimized Ahead-of-Time (AOT) compilation.
• Animation Package Separation: Animation features are in a separate package, saving space for apps without animations.
• ngIf and ngFor Enhancements: Improved performance with ngIf and ngFor enhancements.
• HTTP Interceptor: Efficient handling of network tasks with global HTTP interceptors.
• Template Source Maps: Easier debugging with source maps linking generated code to the original template.

What is the scope?

In Angular, a “scope” acts as a container for the application’s model, providing a space to carry out expressions. These scopes follow a hierarchy, matching the structure of the app’s elements in the DOM. They play a role in spreading events and keeping track of expressions across the entire Angular application.

How does primeng benefit Angular 4 applications?

PrimeNG in Angular 4 simplifies UI development with pre-built, customizable components like tables and charts. It ensures consistency, responsiveness, and easy integration, allowing developers to create professional-looking applications efficiently.

How do you perform Error handling?

Error handling utilizes try-catch blocks, custom errors, and logging for efficient issue management. Strategies such as error codes, descriptive messages, and graceful degradation improve resilience. A well-rounded blend of these methods guarantees strong error management in software development.

How do you use the Angular CLI to generate a new component in Angular 4?

To create a new component in Angular 4 using the CLI, run the command: ng generate component component-name. Replace “component-name” with your desired name. Navigate to the new component directory using cd src/app/component-name. The CLI will generate necessary files like .ts, .html, and .css for your component, facilitating seamless integration into your Angular 4 application.

Explain the purpose of CanActivate in Angular 4?

In Angular 4, the CanActivate interface serves as a route guard, enabling the implementation of the canActivate method. This method plays a crucial role in deciding if a user has the permission to access a particular route. CanActivate is employed for enforcing authorization logic, typically checking user authentication or other conditions before allowing navigation to a specific route.

Explain JIT and AOT in Angular 4.

Angular 4 employs two compilation methods, JIT (Just-In-Time) and AOT (Ahead-of-Time), each influencing the application process uniquely:

JIT (Just-In-Time):

• Dynamically compiles components and templates into JavaScript during runtime.
• Facilitates rapid development and reduces browser downloads.
• May lead to slightly slower startup as compilation occurs on the user’s machine.

AOT (Ahead-of-Time):

• Compiles components and templates before deployment.
• Optimizes application performance with faster startup and smaller files.
• Identifies template errors during the build process.
• Requires longer build times and a build step before deploying, proving advantageous in production.

Describe the concept of transpiling in Angular 4.

In Angular 4, transpiling means converting TypeScript code, which has extra features, into regular JavaScript that browsers can understand. Since browsers only work with JavaScript, this process allows developers to write in TypeScript while ensuring their code works properly on the web. The Angular CLI uses transpilation to turn TypeScript into JavaScript during the build, making it compatible with browsers.

What role does deep linking serve in Angular 4?

In Angular 4, deep linking allows direct access to specific pages through manipulated URLs. It enables users to bookmark and share URLs, ensuring easy navigation to desired content. This feature enhances user experience by providing direct access to specific views, making it convenient for users to reach the intended content through shared links or browser history.

How do you perform isolated unit tests in Angular 4?

To perform isolated unit tests in Angular 4, set up a testing module and create a component instance using TestBed. Interact with the component, trigger events, and use Jasmine’s testing functions to verify expected outcomes. Clean up resources as necessary, and tailor the test suite to suit your component’s specific requirements.

What does Bootstrap do, and how do you incorporate it into Angular?

Bootstrap is a widely used framework for creating responsive websites. In Angular, you embed Bootstrap by installing it with npm or yarn. After installation, you import Bootstrap styles into your Angular project, usually in the styles or angular.json file. This allows you to use Bootstrap’s classes and components, making it easier to design attractive and mobile-friendly Angular applications.

Conclusion

In conclusion, this collection of Angular 4 Interview Questions and Answers provides an essential resource for developers preparing for Angular interviews. Spanning from basic concepts to advanced topics, it offers a comprehensive understanding of Angular 4 development. Whether you’re new or experienced, these questions offer a thorough review, instilling confidence for interviews. Keep these insights close to successfully navigate Angular interviews, reinforcing your expertise and establishing a strong foundation for your development journey.