Top 35+ Angular 9 Interview Questions and Answers 2020

Last updated on by Digamber

Angular is a very popular name among web developers and programmers. There is no doubt, and Angular is one of the most used client-side frameworks. 

Angular is a javascript framework that provides developers with efficient tools to build better web applications. It is a very useful framework for designing robust web applications rapidly, and Angular also enables developers to test and organize the JS code.

Due to the fact that Angular is such a popular framework, it is frequently asked about in developer interviews. Thus if you wish to get a development job and are going to fight an interview for the same, its time you refine your knowledge about Angular. 

To help you accomplish the same, we are here with the top angular 9 interview questions along with their answers.

Check out latest Angular Tutorials.

Why only Angular 9? 

Because Angular’s latest version is Angular 9 so most of our questions will be based on Angular 9, and few questions will be based on older AngularJS version. 

Read all the questions and their answers carefully and get ready to win your next interview. Here we go-

 

1. Give a brief introduction to Angular. 

Angular is a web application framework that is typescript based and is maintained by Google. It enables developers to create robust web applications or even mobile apps by providing tools to build the frontend. These functionalities and tools that Angular offers are easy to use. It is an open-source framework. 

2. Who is Misko Hevery?

Misko Hevery is often called the father of Angular. He is an agile coach at Google. He studied at Santa Clara University and lived in CA. 

3. Name a few features of Angular?

Although Angular 9 offers a variety of features and functionalities to facilitate web application development, some of the well-known features are dependency injection, declarative templates, end-to-end tooling, etc.

4. What do you mean by components in Angular?

Components are utilized to build the UI of the application; thus, components control the look and feel of the Angular Application. So basically, Components are typescript classes. These classes interact with HTML CSS to manage the UI.

5. How to create and configure components in Angular. 

To create components in Angular, @Component decorator is utilized. This @Component decorator is a fraction of the @angular/core module.

To configure a component in Angular, we need to pass data in them.  

6. What is Angular 9 and how it is different from Angular?

Angular’s latest version is called Angular 9. This version of Angular is more efficient, and development using Angular has just got better with Angular 9. 

7. Explain the difference between Angular and AngularJs. 

Angular is a javascript framework that allows developers to build efficient applications using built-in tools and features. 

Angular is an upgrade to AngularJs, and thus it is a better framework for application development. 

Angular is faster to develop applications than Angularjs. 

Angular uses javascript to build an application and, on the other hand, AngularJs utilized typescript. 

Angular is mobile-friendly, but Angularjs was not. 

8. Why do people use Angular? 

Using Angular for application or website development comes with certain advantages. It provides a wide array of tools and functionalities to build scalable websites fast and efficiently. It is a reliable framework for development chores as Google manages it. Further advantages that make people use Angular are as follows-

  • Angular works on MVC patten architecture and two-way binding is supported by Angular 9. 
  • Angular 9 also supports validations. 
  • Both Angular and static templates are favoured in Angular. 
  • Angular supports Restful API and enables developers to create custom directives. 
  • Angular provides many features like animation. 
  • It supports dependency injects and client and server communication. 

9. Name some common or popular Angular features. 

Though Angular offers a wide range of features to facilitate web application development, some notable features are as follows- 

  • Templates
  • Dependency Injection (DI)
  • Directive
  • Code splitting
  • Child-Parent Relationship
  • Data Binding
  • Localization
  • Validation
  • Testing
  • Model View Controller (MVC)

10. Why is typescript useful?

Typescript is useful in a variety of ways like it improves consistency, productivity, modularity, and ease to catch errors. 

11. On what port Angular runs?

Angular runs on 4200 port, but it could be configured. 

12. Explain Modules in Angular?

A module incorporates single or multiple components, but they have nothing to do with HTML. Modules are used for declaring what components of different modules can utilize components. It also declares which class the dependency injector would inject. It gives rise to modularity in your application by managing the components. 

13. Name the latest version of Angular in use?

The latest version of Angular in use at present is Angular 9. 

14. Explain MVC architecture. 

Angular follows the MVC architecture. MVC is the abbreviation for the model view controller. This MVC architecture is a simplified architecture to build modern UI. This architecture provides some of the essential elements you would need to build UI’s for desktop, mobile or even web applications. MVC is the standard architecture being used today to build robust applications. 

15. Can you explain the SPA?

SPA is the abbreviation for a single page application. This type of web improves the speed and overall digital experience by dynamically reloading selected page elements in line with user interactions. Thus this avoids the need for fetching the elements altogether from the server. 

16. Explain AOT. 

AOT compilation or the abbreviation for ahead of time compilation is the process of internal compilation of code. The compiler compiles typescript code and converts the typescript code to javascript code. This occurs once per event per user.

 17. What do you know about Angular material?

Angular material is one of the Angular user interface component libraries. Since it is a UI component library, it allows developers to build attractive web pages that are fully operative and also consistent. The library follows modern principles for web design. 

18. Do you know about Angular directives?

The directive in Angular is of great help as they enable developers to write new and application-specific HTML syntax. Directives are functions that run when the compiler discovers them in DOM. 

19. Name the different types of Directives in Angular?

Different type of Angular directives are as follows-

  • Structural Directives
  • Attribute Directives
  • Component Directives

20. What are annotations in Angular?

To create an annotation array, we use Angular annotations. They use reflect metadata library as to the metadata set of the class. 

21. What are decorators in Angular?

Decorators, as the name suggests, are the design patterns. These design patterns are utilized in order to segregate the modification of a class without altering source code. 

22. What do you mean by ngOnInit () in Angular?

A lifecycle hook called after the initialization of all data-bound properties of a directive has been done by Angular. 

23. How will you define ngOnInit ()?

It can ve defined as follows:

Interface OnInit {
   ngOnInit() : void
}

24. What are the services in Angular 9?

Services in Angular are singleton objects. This singleton objects only instantiate once during application lifetime. Moreover, Angular service retains the data throughout the application’s life by using specific methods comprised of it. 

Thus, Angular services share business, components, functions, and data with other components language and organizing an application. A controller directive can invoke the features of Angular service. 

25. Explain NgRx. 

A group of Angular libraries for reactive extensions is called NgRx. The redux pattern is implemented by NgRx/store by using the RxJS observables belonging to Angular 2. NgRx is useful in a variety of as it can simplify application state to plain objects. It implements a unidirectional flow of data. Many other libraries under NgRx are helpful in a variety of tasks. 

26. What do you know about string interpolation in Angular?

It is a special syntax that displays the component data using template extensions. It is also called mustache syntax.  

27. Explain Angular authentication? 

The Angular authentication process is as follows: 

An authentication API receives user credentials and validates it. The authentication API is present on the server. Once the validation has been done, a JSON web token is reinstated containing information about the current user. JSON web token is then used to identify the user. 

 28. Explain Angular authorization. 

The process or method restricting the access of users is called authorization. Once a user is logged in after authentication, he or she has a certain level of access. This level of access can be configured for different users. This is what we call Angular authorization. 

29. What do you know about the scope hierarchy in Angular?

The scope hierarchy is the organization of $scope objects into a skeleton by Angular. Views often utilize this hierarchy, and in this hierarchy, each view has its unique scope. This format has a parent scope that is capable of holding numerous child scopes.

30. What is the way to generate a class in Angular using Angular CLI?

The following command can be utilized to create a class using CLI:

ng generate class myClass [options]

31. Differentiate between Angular and jquery. 

  • Jquery is a js based library whereas Angular, as we know, is a javascript framework for frontend development. 
  • Angular does support two-way binding, but jquery does not. 
  • Restful API can be consumed in Angular but not jquery has no support for Restful API. 
  • Form validation is available in Angular but not in Jquery. 

32. What is the difference between Angular and javascript expressions?

The significant difference between Javascript and Angular expressions are as follows:

  • We can write javascript expression under HTML tags, but we can do so with Angular expressions. 
  • Filters are available in Angular but javascript has no provision for filters. 
  • The angular expression can’t support loops, conditions and exceptions like javascript do. 

33. Explain Data Binding?

Data binding is the feature in Angular that allows establishing a connection between application data and DOM. This occurs between HTML and typescript or in other words between template and component. 

34. In how many can data bunding be done?

There are 3 ways to attain data binding, and they are as follows:

  • Even binding
  • Two-way binding
  • Property binding

35. Elucidate Angular’s digest cycle. 

Digest cycle in Angular is the strategy to monitor the watchlist to track alterations in the watch variable’s value. A comparison of later and present is done in every digest cycle. 

36. How to trigger a digest cycle process manually?

We can use the $apply() function to trigger the digest cycle process manually. 

37. What is the use of Angular filters?

When we need to format the value of the expression to display it to the user, we make use of Angular filters. These filters can be reinforced to directives, services, template or controllers. We could also create custom filters in Angular. The data is displayed only if a certain criterion is matched, and this is what filters can do by organizing data in such that way. 

38. Name some Angular filters?

The filters in Angular are as follows:

  • json
  • limitTo 
  • currency 
  • orderBy
  • date 
  • filter 
  • lowercase
  • number

Conclusion

So, these were some Angular 9 interview questions along with their answers. Javascript frameworks are getting more and more popular due to the fact that they are a great way to build applications faster and efficiently. The tools and supports Angular provides to its user base makes it the best framework to use.

Because this technology is so famous, its often enquired about in interviews. Thus this becomes essential for you to have a good understanding of the topic so that you don’t feel speechless in front of the interviewer.

Even though if you have not used the Angular framework ever still these questions and their answers are enough to give you a clear vision of the technology. If you already knew about Angular, I hope this article helped you revise old concepts and bolster your confidence before you appear in the interview.

Thanks for reading and I hope it helps.

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Digamber

Digamber Rawat is from Uttarakhand, located in northwestern part of India. He is a Full-stack developer by profession and a primary author of this blog.