50 Angular 2 Interview Questions for Experienced and Freshers

Angular 2 is a popular front-end framework that has gained significant popularity among developers for building dynamic web applications. If you are preparing for an Angular 2 interview, it is essential to have a solid understanding of its core concepts and features. To help you ace your interview, this article has compiled a list of the top 50 Angular 2 interview questions and answers. Read more to learn about Angular JS certification courses.

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3. Conclusion

Q1. What is Angular 2 and how does it differ from AngularJS?

Ans: The common definition about Angular 2 is one of the most asked Angular 2 interview questions. Angular 2 is a complete rewrite of the original AngularJS framework. It was designed to address performance and modularity issues in AngularJS. Unlike AngularJS, Angular 2 is built using TypeScript, a superset of JavaScript, which brings static typing and enhanced tooling to the development process.

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Q2. Explain the concept of components in Angular 2.

Ans: Components are the basic building blocks of an Angular 2 application. They encapsulate the HTML, CSS, and logic required for a specific part of the user interface. Components promote modularisation and reusability, enabling developers to create complex UIs by combining and nesting components.

Q3. How does data binding work in Angular 2?

Ans: Angular 2 offers two-way data binding, meaning changes in the model automatically update the view, and vice versa. This is achieved using syntax like [(ngModel)] which binds properties between the component and the view. It streamlines the development process by reducing the need for manual DOM manipulation.

Q4. What is Dependency Injection in Angular 2?

Ans: Dependency Injection (DI) is a design pattern in which components receive their dependencies from an external source rather than creating them themselves. Angular 2's DI system allows for better testability, maintainability, and flexibility by decoupling components from their dependencies.

Q5. Explain the purpose of decorators in Angular 2.

Ans: This is one of the frequently asked Angular 2 interview questions. Decorators are a feature of TypeScript used in Angular 2 to enhance classes. They allow you to attach metadata to classes, methods, properties, and parameters. In Angular 2, decorators are extensively used to define components, services, modules, and more.

Q6. What is a service in Angular 2?

Ans: Services are used to encapsulate reusable business logic and data manipulation within an Angular 2 application. They provide a way to share data and functionality across multiple components. Services are typically singletons, ensuring that only one instance exists throughout the application.

Q7. How does routing work in Angular 2?

Ans: Angular 2 interview questions are very common angular questions to be asked. Angular 2 offers a powerful routing system that enables the creation of single-page applications. The RouterModule is used to configure routes and navigation. It maps URLs to components, allowing users to navigate between different views without refreshing the entire page.

Q8. What are Angular 2 directives?

Ans: Angular 2 directives are instructions in the DOM that tell Angular how to manipulate the Document Object Model. Angular 2 has three types of directives:

• Component Directives: Used to create custom components.

• Attribute Directives: Modify the behaviour or appearance of elements.

• Structural Directives: Alter the layout of the DOM by adding or removing elements.

Q9. Explain the concept of Angular 2 templates.

Ans: Templates are a fundamental part of Angular 2. They define how the user interface should look and behave. Templates use a combination of HTML and Angular-specific syntax to display data, bind to events, and perform logic directly in the HTML markup.

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Q10. What is Angular CLI?

Ans: This is one of the important Angular interview questions that commonly appears in the Angular 2 interview process. Angular CLI (Command Line Interface) is a powerful tool that simplifies the development process by generating code, managing dependencies, and providing development and build tools. It enhances productivity by automating common tasks and promoting best practices.

Q11. How does change detection work in Angular 2?

Ans: Angular 2 employs a mechanism called change detection to track changes in the application's state and update the view accordingly. It uses a tree of change detectors to efficiently determine which parts of the view need to be updated, minimising unnecessary rendering.

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Q12. What is Angular 2 Module?

Ans: An Angular 2 module is a logical grouping of components, directives, services, and other pieces of an application. Modules help organise code and facilitate lazy loading, which improves the application's performance by loading modules on-demand.

Q13. Explain the concept of Observables in Angular 2.

Ans: Angular 2 interviews are incomplete with this one of the most asked Andrew 2 interview questions. Observables are a core part of Angular 2's reactive programming paradigm. They are used to handle asynchronous operations, such as HTTP requests and event handling, in a more structured and manageable way. Observables allow for easy composition and manipulation of asynchronous data streams.

Q14. How do you handle forms in Angular 2?

Ans: Angular 2 provides two approaches for handling forms: template-driven forms and reactive forms. Template-driven forms rely heavily on directives in the template, while reactive forms are defined programmatically using form controls and provide more control and flexibility.

Q15. What is Angular 2's NgZone?

Ans: Angular 2’s NgZone plays a greater role in understanding what questions will be asked in the Angular 2 interview questions for experienced professionals. NgZone is a core service in Angular 2 that helps manage and optimise change detection. It runs change detection in a zone, which is a context where asynchronous tasks are tracked and managed. NgZone is particularly useful for improving performance in applications with heavy asynchronous operations.

Q16. Explain the concept of Pipes in Angular 2.

Ans: Pipes are used to transform and format data before displaying it in the UI. They allow you to manipulate strings, dates, numbers, and more. Angular 2 provides built-in pipes and also allows you to create custom pipes to suit your application's specific requirements.

Q17. What is Ahead-of-Time (AOT) Compilation in Angular 2?

Ans: AOT Compilation is a process in which Angular templates are compiled to JavaScript during the build phase, before the application is served to the browser. This improves performance by reducing the amount of work the browser needs to do at runtime, resulting in faster initial loads and improved security.

Q18. How can you handle HTTP requests in Angular 2?

Ans: Angular 2 provides an HTTP module that facilitates making HTTP requests to a server. You can use the HttpClient service to send requests, handle responses, and perform tasks such as error handling and data transformation.

Q19. What are Angular 2 guards?

Ans: Guards are used in Angular 2's routing system to control navigation based on certain conditions. They allow you to protect routes, manage authentication, and implement role-based access control.

20. How does Angular 2 support internationalisation (i18n)?

Ans: One of the most commonly asked Angular 2 interview questions is this one, which frequently appears in most of the Angular interviews. Angular 2 offers built-in support for internationalisation, allowing you to create applications that can be easily translated into different languages. The i18n attribute and related tools help you mark translatable text and generate translated versions of your application.

Q21. Explain the concept of lazy loading in Angular 2.

Ans: Lazy loading is a technique used in Angular 2 to improve the initial loading time of an application. With lazy loading, modules are loaded only when they are actually needed, rather than all at once when the application starts. This approach is especially beneficial for large applications with multiple features or sections. By loading modules on-demand, the application's initial bundle size is reduced, resulting in faster load times for users.

Q22. What is the purpose of the Angular 2 TestBed?

Ans: The TestBed is an important part of Angular 2's testing infrastructure. It provides a testing module environment that allows you to configure and create instances of components and services for testing purposes. The TestBed is used to set up a testing module with the necessary components, services, and dependencies. This allows you to create a controlled environment in which you can test the behaviour and interactions of your application's components and services.

Q23. Explain the concept of zones in Angular 2.

Ans: Zones are a core concept in Angular 2's change detection mechanism. A zone is an execution context that tracks asynchronous operations within a specific code block. Angular 2 uses zones to detect and manage changes in the application's state. When an asynchronous task, such as a user interaction or an HTTP request, is performed within a zone, Angular 2 is notified of the change and can trigger the appropriate change detection mechanisms. This helps ensure that the view reflects the latest state of the application.

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Q24. What are the key differences between NgModule and Component in Angular 2?

Ans: NgModule and Component are both important concepts in Angular 2, but they serve different purposes. An NgModule is a container for a logical group of components, directives, services, and other related code. It helps organise and encapsulate different parts of an application. Components, on the other hand, are the building blocks of the user interface. They encapsulate HTML, CSS, and logic required for a specific part of the UI. While an NgModule provides an organised structure for your application, a Component defines the visual and interactive aspects of the UI.

Q25. How does Angular 2 handle error handling and exception management?

Ans: One of the common Angular interview questions is this Angular 2 handle error handling and exception management topic which is asked in every Angular 2 interview. Error handling is crucial for creating robust and reliable applications. In Angular 2, error handling can be approached in various ways. For asynchronous operations such as HTTP requests, the HttpClient module provides mechanisms to handle errors using RxJS Observables. By subscribing to the Observable returned by an HTTP request, you can handle both successful responses and errors in a structured manner. Additionally, Angular 2 allows you to define global error handling using the ErrorHandler class.

Q26. Explain the concept of content projection in Angular 2.

Ans: Content projection, often referred to as "ng-content," is a powerful feature in Angular 2 that enables the creation of reusable components with flexible templates. Content projection allows a component to accept arbitrary content and display it within its template. This is particularly useful when creating components like dialogs, tabs, or card components, where the content can vary while maintaining a consistent structure.

Q27. How does Angular 2 support server-side rendering (SSR)?

Ans: Server-side rendering is a technique used to improve the initial rendering performance of web applications by rendering the HTML on the server before sending it to the client. Angular 2 provides built-in support for server-side rendering through a module called Angular Universal. Angular Universal allows developers to pre-render Angular applications on the server, delivering optimised HTML to the browser. This can significantly improve the time it takes for the initial content to become visible to users, leading to better search engine optimisation (SEO) and improved user experience, especially on slow networks or devices.

Q28. What is the Angular 2 ChangeDetectorRef used for?

Ans: The ChangeDetectorRef is an important part of Angular 2's change detection system. It is a service that provides methods to manually trigger change detection in a component and its child components. Change detection in Angular 2 is automatic and efficient, but there are scenarios where you might need to manually trigger it. For example, if you modify the state of a component outside of Angular's normal lifecycle hooks, you can use ChangeDetectorRef to inform Angular that changes have occurred and the view needs to be updated.

Q29. How does Angular 2 handle security concerns, such as cross-site scripting (XSS)?

Ans: Security is a critical aspect of web applications, and Angular 2 provides mechanisms to mitigate common security vulnerabilities like cross-site scripting (XSS). Angular's built-in data binding and sanitisation features help prevent XSS attacks by automatically escaping potentially malicious content. Angular's data binding syntax ensures that user-generated content is treated as text and not executable code. Additionally, Angular's DomSanitiser service allows you to explicitly mark content as safe for rendering, while removing any potentially harmful code.

Q30. What is NgRx in the context of Angular 2?

Ans: Every one of the Angular 2 interview questions are filled with this type of topics which forms a essential topic in Angular interviews. NgRx is a state management library inspired by Redux, designed to manage complex state in Angular applications using a predictable and reactive approach. It leverages the principles of unidirectional data flow and immutability to manage the application's state in a centralised store. NgRx consists of several core building blocks, including actions, reducers, effects, and selectors, which work together to manage state changes, side effects, and data retrieval.

Q31. What is Angular's AOT compilation, and how does it differ from JIT compilation?

Ans: Ahead-of-Time (AOT) compilation is a process in which Angular templates are compiled during the build phase before the application is deployed to the browser. This results in smaller bundle sizes, faster initial load times, and improved security. Just-in-Time (JIT) compilation, on the other hand, compiles templates in the browser at runtime, which can lead to slower initial loads. AOT also helps detect template errors during the build process, while JIT may encounter errors only at runtime.

Q32. Explain the concept of dependency injection in Angular and its benefits.

Ans: Dependency Injection (DI) is a design pattern in which components receive their dependencies from external sources rather than creating them. In Angular, DI is used to provide services and other dependencies to components, promoting modularity, testability, and flexibility. Benefits of DI include easier unit testing, better code reusability, and improved maintainability as components remain decoupled from their dependencies.

Q33. What are the differences between ngOnChanges and ngOnInit lifecycle hooks in Angular?

Ans: The ngOnChanges hook is triggered whenever the component's input properties change, allowing you to react to changes in data from a parent component. The ngOnInit hook is called once after the component is initialised and its inputs are set. It is used for initialisation tasks that need to be performed once, such as fetching data from a service. In summary, ngOnChanges is reactive to input changes, while ngOnInit is used for one-time initialisation tasks.

Q34. How can you optimally structure and organise an Angular project?

Ans: A common practice for organising an Angular project is to use the module-based architecture. Create feature modules that group related components, services, and directives together. Keep the modules focused on specific functionality, promoting reusability. Organise folders by feature, rather than file type, to improve maintainability. Follow Angular's style guide recommendations for naming conventions, folder structure, and coding standards.

Q35. What is the purpose of the Angular service worker and how does it enhance web applications?

Ans: The purpose of the Angular service worker always is one of the fundamental Angular 2 interview questions. The Angular service worker is a built-in feature that enables Progressive Web App (PWA) capabilities. It provides features like caching, background synchronisation, and offline access, enhancing the user experience even in unreliable network conditions. The service worker caches assets, allowing the application to load faster on subsequent visits. It also enables background syncing of data, improving data consistency between the client and server.

Q36. What are the key differences between NgZone and ChangeDetectorRef in Angular?

Ans: NgZone is used to manage zones in Angular, tracking asynchronous tasks and triggering change detection when tasks are complete. ChangeDetectorRef, on the other hand, is used to manually trigger change detection within a component and its children. While NgZone helps manage zones and optimise change detection, ChangeDetectorRef gives you control over when change detection is performed.

Q37. How does Angular's HttpClient handle error responses from HTTP requests?

Ans: When using HttpClient for HTTP requests in Angular, error responses are handled through RxJS Observables. You can use operators such as catchError or retry to manage errors in a more structured manner. For example, you can catch specific error status codes, handle retries, and provide user-friendly error messages. By subscribing to the Observable returned by the HTTP request, you can handle errors, success responses, and other data.

Q38. Explain the concept of zone.js in the context of Angular.

Ans: zone.js is a library that hooks into asynchronous tasks and helps Angular detect changes in the application's state. It enables the NgZone service to track tasks within a zone and triggers Angular's change detection mechanisms. Zone.js is crucial for managing asynchronous operations and ensuring that Angular updates the view when the application's state changes due to events like HTTP requests, timers, and user interactions.

Q39. What is the purpose of the trackBy function when using *ngFor in Angular?

Ans: The trackBy function is used to improve the performance of Angular's *ngFor directive when rendering lists. By default, Angular uses the object's identity to track changes and updates the DOM accordingly. However, using a trackBy function allows you to provide a unique identifier for each item in the list. This enhances performance by reducing unnecessary re-rendering when the list is updated.

Q40. How can you optimise the performance of an Angular application?

Ans: The performance of an Angular application is considered as one of the frequently asked Angular 2 interview questions. Performance optimisation in Angular involves various strategies. Use AOT compilation to generate smaller bundles. Minify and compress assets. Implement lazy loading to load modules on-demand. Use the Angular service worker to enable caching and offline access. Opt for the OnPush change detection strategy to minimise change detection cycles. Employ lazy loading for images and other media. Reduce unnecessary rendering and DOM manipulations.

Q41. Explain the concept of multi-module applications in Angular.

Ans: Multi-module applications in Angular involve breaking down the application into multiple feature modules, each focused on a specific area of functionality. This promotes modularity, reusability, and maintainability. Feature modules can be loaded on-demand using lazy loading, enhancing the application's performance. Each module can have its own components, services, and other dependencies, creating a clear separation of concerns within the application.

Q42. What is the role of the ActivatedRoute and Router in Angular?

Ans: The ActivatedRoute and Router are essential components of Angular's routing system. ActivatedRoute provides information about the currently activated route, including route parameters, query parameters, and data. The Router manages navigation between different views and components based on the defined routes. It allows you to configure routes, handle route changes, and navigate between different parts of your application without full page refreshes.

Q43. How does Angular support unit testing?

Ans: Angular provides a robust testing environment that supports both unit testing and integration testing. The TestBed helps create isolated testing modules, allowing you to configure and instantiate components, services, and dependencies. You can use tools such as Jasmine for writing test suites and assertions. Angular's testing utilities and asynchronous testing support ensure reliable and effective unit testing. The TestBed and ComponentFixture also enable you to simulate component interaction and change detection during tests.

Q44. What is the purpose of Angular's NgIf and NgSwitch directives?

Ans: The NgIf directive is used to conditionally render elements in the DOM based on a given condition. It is commonly used to show or hide elements based on user interactions or data availability. The NgSwitch directive, on the other hand, is used to conditionally display elements based on multiple cases. It is useful when you need to render different templates based on different values of a variable.

Q45. Explain the concept of content child and view child in Angular.

Ans: The difference between content child and view child is considered as one of the commonly asked Angular 2 interview questions. Content child and view child are decorators used in Angular to access elements within a component's template. @ViewChild is used to access a single element or directive within the component's view, while @ContentChild is used to access elements projected into the component using content projection. Content child is typically used when you want to manipulate projected content, while view child is used to access elements within the component's own template.

Q46. What is Angular's ElementRef used for?

Ans: ElementRef is a class in Angular that provides direct access to the DOM element of a component. It is often used when you need to interact with the DOM directly, such as manipulating styles, classes, or properties of an element. However, using ElementRef to directly access and modify the DOM should be done cautiously, as it can potentially lead to security vulnerabilities and make the application harder to test and maintain.

Q47. What is the purpose of the @HostListener and @HostBinding decorators in Angular?

Ans: @HostListener is a decorator that allows you to listen for events on the host element of a directive or component. It is used to bind event listeners to the host element and trigger methods in response to events. @HostBinding, on the other hand, is used to bind properties of the host element. For example, you can use @HostBinding to set styles or classes on the host element based on certain conditions. This is intended to be one of the most important Angular 2 interview questions for experienced professionals

Q48. How can you handle authentication and authorisation in an Angular application?

Ans: Angular provides tools and techniques to handle authentication and authorisation. You can use Angular's built-in HTTP module to interact with authentication endpoints. Implement route guards to control access to certain routes based on user roles or permissions. Store authentication tokens in cookies or local storage. Libraries like NgRx can be used to manage application state related to authentication. Angular's HttpClientModule and canActivate guards are commonly used for these purposes.

Q49. Explain the concept of the Angular animation module and how it is used.

Ans: The Angular animation module allows you to create and manage animations within your Angular applications. It provides tools to define animations for various components and elements, such as transitions, keyframes, and state changes. The animation module uses a declarative syntax and integrates seamlessly with the component lifecycle and Angular's change detection mechanism. By using animations, you can enhance the user experience by adding subtle visual effects and transitions to your application's UI components.

Q50. What are the differences between reactive forms and template-driven forms in Angular?

Ans: One of the essential Angular 2 interview questions for experienced is the differences between reactive forms and template-driven forms in Angular. Reactive forms and template-driven forms are two approaches for handling forms in Angular. Reactive forms involve creating form controls programmatically in the component and providing explicit data bindings between the form controls and the template. This approach offers greater control and flexibility, making it suitable for complex forms and validation scenarios. Template-driven forms, on the other hand, rely heavily on directives in the template to define and manage form controls. They are more suitable for simpler forms and require less boilerplate code.

Conclusion

Angular 2 requires a deep understanding of its core concepts, components, services, and features. By preparing answers to these top 50 Angular 2 interview questions and answers, you will be well-equipped to understand the role of these and thus impress potential employers and demonstrate your expertise in this powerful front-end framework. Students with these will succeed in their careers as proficient web developer.