Top Angular Interview Questions and Answers

Angular is a ubiquitous front-end JS framework for application building. As Angular’s prominence grows, there is a strong need for Angular experts who know the best practices of Angular development. This post will discuss some often requested Angular Interview questions and ways to respond to them. 

Table of Content

  1. List of Top 13 Angular Interview Questions and Answers
  2. Conclusion

To polish up on your fundamentals,  you can correspond to this post for additional clarification. Let us now proceed!

1. List of Top 13 Angular Interview Questions and Answers

1.1 What is Angular? Why was Angular introduced into the Market as a Client-Side Framework?

If we go by the stats then, there are around 1.2 million Angular developers working on different technologies at the moment. With over 12K contributors, Angular is also one of the most popular open-source frameworks. Also, the majority of developers would know this for a fact that Angular is an open-source typescript framework used to develop Single Page application/s. Angular uses HTML and typescript code libraries to develop these applications. Angular components are built around reusable and shareable components such as RESTful APIs for connecting to old systems, databases, and apps.

To answer the second part of this question. Prior to the advent of JavaScript-based client-side frameworks, dynamic websites were created using templates. Templates were nothing more than HTML code with blank areas to display data and content to be fed into. Typically, this information was obtained from a database. We would then provide the created HTML content to the user after integrating the template and data. As you can see, it was a bit difficult and required a lot of processing in certain circumstances.

To address these challenges, individuals devised a new method in which they deliver the data needed to generate a page from their web servers to web browsers and then let JavaScript mix this data with a specified template. Then the data was sent to the client via the internet in a programmable format like XML or JSON. Ever since the introduction of Angular, the performance of apps has improved. Some of the reasons for using angular over traditional web technology are, it facilitates client and server communication, supports Two-way data binding, facilitates lazy loading,  provides different Angular templates, and facilitates the building of a single-page application.

1.2 Which is the Latest Version of Angular and What are the Key Differentiating Factors?

Which is the latest version of Angular and what are the key differentiating factors?

This is one of the most commonly asked Angular interview questions. It is asked to check whether the candidate is putting efforts towards updating himself/herself about the latest updates.. The latest version of Angular is Angular 13.1.1 which was recently released at the end of 2021 and it brings all the new advances, updates and features to help your team to build a good angular application. Some of the aspects that makes this version different from the previous one is that, with the release it has expanded Ivy-based features and optimizations, and collaborating with the excellent Angular community. Also,  Angular is quite consistent in providing a smooth, stable update process for your teams and projects. Here are some of the most visible changes in the latest version of Angular

  • When it comes to the View engine, it is no longer a part of Angular V13. This clearly means that there will be a boost seen in Angular development because of the use of Ivy-based features. Apart from that, there is a small question on the dependency on Ngcc. Teams can look for a faster compilation method for meta descriptions and summaries. 
  • To better serve developers, the Angular Package Format (APF) has been streamlined and modernized using Angular Package Format Changes (APF). Angular team has also removed older output formats, that is inclusive of View Engine-specific metadata to streamline the APF in this latest version.
  • Component Update on API includes that Ivy improved the quality of coding for developers by allowing them to dynamically create components. The API has now been streamlined after this update. You can now dynamically create components that require a lot of boilerplate code prior to the changes in Angular v13.

1.3 What are the Components in Angular?/What is Angular Component?

In any framework, whether Vue or Angular, the components are the fundamental building blocks that make the interface different. It is the same with the Angular user interface as well. A component is made up of HTML, CSS, and TypeScript for a specific area of a user interface. For every Angular application, there is at least one component, this root component is the one that helps you connect all the components in a hierarchy with the page document object model (DOM). Consider this to be a special HTML element that can only understand the Angular framework. These Angular components are separated, which means that styles and code from one Angular component do not influence other Angular components because they are namespaced by the compiler. The Angular framework then assembles multiple values from these components to create the user interface that will be rendered by the browser. 

In this framework, the components are organized into NG modules and this module collects the necessary information and converts it into functional sets into a defined set of Ng modules. There is a root module that initiates bootstrapping. These components also have classes which are known as decorators and then there are metadata, application components, and others.

1.4 What are Some of the Advantages of Angular over Other Frameworks?

What are some of the advantages of Angularjs over other frameworks?

The Angular framework has a noteworthy contribution to the developer’s community. Some of the most popular advantages of Angular are listed here:

  • MVVM Architecture: This is the simplest form of  MVC architecture where the Angular Framework is embedded into a real MVC model and then a more secure set up of MVVM is initiated. MVVM supports two-way data binding between the View and ViewModel elements of MVVM- Model-View-ViewModel system. It eliminates unnecessary codes and ensures there is simpler development.
  • Ng Modules: As we discussed, modules are another essential part of Angular. It is made up of many design patterns like components (Root component, parent component and more), directives(structural directives and attribute directives), pipelines, and services (angular service) that aid in the construction of angular applications.
  • Dependency injection: This functionality enables developers to quickly work with components that are dependent on other components.
  • Other general benefits include clean and manageable code, unit testing, reusable components, data binding, and a responsive experience that is second to none.

1.5 What is an AOT Compilation? What are the Advantages of AOT?

If you want to crack this one, you must know AOT(ahead of time). An angular application is made up of components and templates that a browser cannot comprehend. So, every Angular app requires a compilation process before it runs in the browser. The Angular compiler accepts TypeScript code, compiles it, and then delivers an output in JavaScript code. It is known as AOT compilation and it occurs just once per user, per event. This is true for all angular applications.

For AOT, angular supports two types of compilation:

  • JIT (Just-in-Time) compilation: Here the program is built within the browser while it is running so you can say it happens in real time or just in time when needed.
  • AOT (Ahead-of-Time)- Here as the name suggests ahead of time is where the compilation occurs before the application is built.

The advantages of being ahead of time in the compilation process are:

Less errors: The errors are easily detected and handled throughout the construction phase.

Enhanced Security: Before an application runs in the browser, the AOT compiler inserts HTML and templates into the JS files, eliminating the need to read additional HTML file/s and thereby improving angular application security.

Faster results- As the program is built before running within the browser(or ahead of time), the browser loads the executable code and renders it promptly.

Minimal Ajax Requests: Just because the compiler provides the external HTML templates and CSS files together with the application; thus you can send separate AJAX requests for those source files and reduce the AJAX request count to only the necessary ones.

1.6 Explain What is String Interpolation and Property Binding in Angular?

If we go by the term interpolation then interpolation means interconnecting and binding strings with data. This is also called one-way data binding. In this process, there is a special syntax used under double curly braces to display the component data. Within the brackets, you can include the JavaScript expressions. The Angular expression needs can also be executed to retrieve the desired outcomes and insert HTML code into it. As a part of this cycle, the code needs a regular update and storing process. 

Say for instance if you want to store data, then you can store data as

{{data}}
{{data}}

1.7 Explain the Concept of Dependency Injection?

If you want to get selected for your dream job, the key to it is to know every little concept of the Angular framework. Dependency injection is one of the key aspects in Angular. Also sometimes known as DI, It is a software design paradigm that addresses how code obtains its dependencies. The operation “config” uses dependency injection to get aspects of the application that must be configured when the module is loaded.

In dependency injection, there are majorly three ways of handling dependencies.

  • The first way is to initiate the use of a new operator 
  • Another way is to determine it by keeping a global reference value.
  • The last way is to move the data to the place where it is needed the most.

1.8 Explain What is MVVM Architecture?

The MVVM design is important in removing tight coupling between components. This architecture is made up of three parts:

Model: A model is a representation of the business logic and data of a certain application. To put it another way, it is made up of entity structures. The model contains the business logic, as well as model classes, remote and local data sources, and the repository.

View: The view is the visible layer of the program that contains the UI code. The action of the user is delivered to the ViewModel through the view. However, it does not receive a direct answer. To receive a response, the view must subscribe to the ViewModel’s observables.

ViewModel: The View Model is the application’s abstract layer that links and functions as a bridge between the View and the Model. It has no idea which View should be used because it does not have direct access to the View. The two are linked through data binding and the ViewModel records any changes made to the View and makes the required modifications to the Model.

1.9 List Out Differences Between AngularJS and Angular

Angular technology has a spinoff effect on business development strategy. But there is always this confusion between AngularJS and Angular framework which needs to be differentiated. Let’s simplify this with a differentiating table. 

Differentiating ParameterAngular JSAngular
ArchitectureIt is backed up by an MVC modelThis one is backed up with components and directives
Supporting LanguageJavaScriptTypescript
Mobile App supportDoes not cover all the platformsIt encompasses the usage of almost all software platforms.
General ManagementFor bigger projects with complex and big source code.It is better and easy to manage and code larger projects.
Dependency InjectionNot ApplicableSupports at  many levels

1.10 What are the Different Types of Data Binding in Angular?

What are the Different Types of Data Binding in Angular?

Data Binding in Angular does not come one way, there are two ways of doing it- one-way data binding and two-way data binding. To elaborate, one-way data binding is simple. Data flows unidirectional in one-way data binding, i.e. from source to destination. It is a process where you can manipulate views via models. You can do one way data binding in three ways- String Interpolation, Event binding, and property binding. This means that if you decide to make changes in  typescript code then it will show the interpretations  in HTML. Following are two main aspects of one-way data binding which needs to be achieved: 

  • String Interpolation 
  • Property tying Event tying

The second type of data binding is Two-way data binding. This on the other hand, allows data to sync the views from all the used models and update it as per views of all other data. With two way data binding, you will be able to share data between component class and template. 

1.11 What is Lazy Loading in Angular?

Lazy loading is a technology of angular that allows you to load JavaScript components when a specific route is activated. It improves application load time speed by splitting the angular application into many bundles. When the user navigates by the app, bundles are loaded as needed.

Lazy loading helps to render module on demand, which helps to reduce load times. We must use the class decorator to create an Angular module @NgModule, and the decorator uses a metadata object that defines the module.

1.12 Explain Architecture of Angular? or Explain Different Blocks in Angular?

(1) Template

(2) Component

(3) Module (Group of Components)

(4) Binding

(5) Directives 

(6) Service

(7) Dependency Injection

To understand the architecture, it is equally important to know which aspects act as a building block in the development process. There are seven different types of block which contribute in making this architecture robust and strong. Let us see each of them briefly.

(1) Template 

In Angular, the component’s view is defined by a template. This means an angular template is a form of HTML that will state how Angular behaves and rendering of components.  If you see a template, it would rather look like a regular HTML page with a little to more smaller differences.

(2) Components

If you see any Angular project, you’ll find at least one component called root component which is responsible for connecting component hierarchy to a page document object model (DOM). Each component defines the class that contains the application data and business logic. You can also link to the HTML template that defines the view that will be displayed in the target app. A view is a patch of screen that is controlled by a component.

(3) Module (Group of Components)

Your conventional Angular app will always have an App Module which is also called root module. The Module is very important when you decide to launch an application as it will be like a pathway to your developing application. Each module, you will also see a group of components playing an equally important part of the Angular project. 

(4) Data Binding

Data binding is essential in order to communicate between a template and its component. Data binding is also necessary for communication between parent component and child components or root and functions. In Angular, you can define communication between a component and the existing DOM element, making it very easy to develop dynamic websites or  applications without worrying about data pulling and pushing.

(5) Directives 

When it comes to directives, any angular component you take will not be as good if they don’t have a directive in it. As components are equally involved in creating a good Angular app similarly, directives (be it Structural directives or attribute directives) are important in building blocks of Angular projects. You can use Built-in Angular directive class like the Ng class. This is a great option for using existing Angular attribute directives.

(6) Service

When you use a service class, you must know that it is used for data or logic that isn’t associated with a specific view and that you want to share across components. You use service class with Injectable decorator that comes right after the service class definition to provide the metadata that allows your service to be injected as a dependency into client components. In this way, you can increase modularity and reusability, Angular separates components from services.

(7) Dependency Injection

Dependency Injection is built into the Angular framework and used throughout to provide new components with the services or other resources they require. Components consume services; that can be injected into a component, giving the component access to that service class.

1.13 Explain What is the Difference Between Angular and Backbonejs?

Also, the final question in this list of angular interview questions can be related to backbone js. Now if you don’t know what backbone js is then here’s the quick brief about it. Backbone js is a javascript library with a JSON interface and is completely dependent on Javascript library functions. Most of the time, it is used because it is light weighted and supports dependency injections. Let’s get clearer with the difference table.

Differentiating TableBackbone JSAngular
TypeBackbone.js is completely dependent on Javascript libraries with RESTful JSON interface and MVP framework.Everyone knows angular is an open-source JS-based front-end app development framework that uses HTML for newer attributes.
ArchitectureIn Backbone.js, you can find MVP architecture but it does not allow data binding.In Angular, the similar aspect is MVC architecture but it also allows two-day data binding for improved application activity.
DOMBackbone.js follows a direct DOM approach where the changes in architecture are made as per the existing DOM element.Angular prime space of working is HTML and as per the changes the redevelopment of DOM takes place.
PerformanceIn tiny data sets or small webpages, Backbone.js offers a substantial speed advantage over Angular.Angular has comparatively higher efficiency in terms of performance because of two-way data binding.
Community SupportBacked up by a great community of developers, there is continuous support on each problem.Developed by google and the support is impeccable for Angular framework.

2. Conclusion

We believe this post on Angular Interview Questions clarified the kind of queries that will be posed and ways to respond to them. However, if you intend to study Angular and maybe pursue a career in it, accreditation would be beneficial.

Additionally, you may research and become comfortable with interview questions pertaining to those other frontend frameworks, such as CSS, or ReactJS.

Are there any questions you’d want to ask us? If you have any criticism or queries, please leave a remark in the comment section  below.

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Itesh Sharma

Itesh Sharma is core member of Sales Department at TatvaSoft. He has got more than 6 years of experience in handling the task related to Customer Management and Project Management. Apart from his profession he also has keen interest in sharing the insight on different methodologies of software development.

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