Prepare for Common Angular Interview Questions

India is a global hub for Angular development companies, with organisations employing hundreds of skilled professionals and providing quality service to customers worldwide. Angular promises the ability to create fast, dynamic, and scalable web applications. It is an in-demand technology that helps develop the speed and features online users want when logging into their apps. 

If you’re looking for a job working with this JavaScript framework, you’ll need to show potential employers you know what Angular is and why you’d use it. This overview can help you make a great impression and launch your dreams of becoming an Angular developer and building a career around working with this popular framework.

What is the Angular framework?

You may encounter this as an Angular interview question, but your interviewer will likely treat the answer as common knowledge. Still, we’ll review the basics to ensure you have a succinct answer.

Angular is an open-source framework invented by Miško Hevery and developed by Google, which released its initial version in 2011. It originally focused on creating single-page applications, but you can now also use it to build dynamic front-end web-based applications. YouTube is a well-known example of using Angular.

Angular’s development came from necessity, as Google found web development growing overly complex. So, the tech giant developed Angular to simplify the process when you didn’t need complex functionality. In Angular, you’ll use declarative templates, dependency injection, and end-to-end tooling in your application development, which helps break code into smaller bits of information for a simplified development process.

The framework is written in TypeScript, which uses HTML syntax. This helps to make Angular a consistent and efficient framework with a code base that users can easily understand and maintain.

What are the advantages of Angular?

You may experience many benefits from using Angular. Examples include:

• Support for two-way data-binding so that the corresponding model state reflects any changes to the user interface (and vice versa)

• Excellent for building responsive, progressive apps with clean code that users can enjoy on various platforms

• Supports both static and Angular templates

• Dependency injection lets you streamline components

• Lets you add custom directives to provide program logic

• Provides client and server communication

• Includes robust features, including routing, event handlers, state management, animation, etc. 

If you’re asked this question in an interview, it can help to give a specific example of when you chose to use Angular over another approach and why.

Preparing for your Angular interview

Since Angular is a broad framework requiring several skills, you can expect a wide-ranging set of questions. Interviewers might ask you about JavaScript, TypeScript, the basics of Angular or more advanced concepts, reactive programming, and more. We’ve collected some common questions in the following sections to help you prepare. 

10 Angular interview questions 

In addition to facing questions about what Angular is and what the common features are, you might encounter one or more of the following questions.

1. What are single-page applications (SPA)?

Why are they asking? Making everything accessible on a single page is a current trend, and they want to know if you’re up to date on the latest developments in the field.

Sample answer: An SPA is a web application that loads once with new features, providing a seamless user experience. This means the user can use the application without downloading new content pages from the server, which speeds things up. Angular can generate the content dynamically because JavaScript can manipulate elements on the page itself. 

2. Explain dependency injection.

Why are they asking? This is a core concept in Angular.

Sample answer: Dependency injection refers to the application design pattern. Any service in Angular that has some functionality is dependent. These dependencies can be smoothly injected into components and directives to let services depend on other services throughout the application. 

3. What are the differences between Angular and AngularJS?

Why are they asking? You’ll need to be able to select between these two when working in Angular.

Sample answer: Angular uses TypeScript, components, and directives and supports all popular mobile browsers. On the other hand, AngularJS uses JavaSript and Model-View-Controller (MVC) design, but mobile browsers don’t support it. Angular is also faster than Angular JS because it has upgraded features.

Additionally, Angular makes it easier to create, maintain, and manage complex applications with its superior structure. That’s more difficult to manage with AngularJS. Angular also supports dependency injection, unlike AngularJS. Plus, AngularJS is no longer supported. You’ll only see updates to Angular. 

4. What are the advantages of Angular vs React?

Why are they asking? Your employer will want to know you have the understanding needed to make the best choice for their front-end development project.

Sample answer: Angular’s support for bidirectional data binding and dependency injection is the biggest difference. React is only unidirectional and requires developers to accomplish the dependencies or use a third-party library. Angular uses TypeScript, while React uses JavaScript. You can use Angular for web and mobile development, but you can only use React in UI development.

5. What is two-way data binding?

Why are they asking? To share data in the application, you must use binding, so you’ll need to be able to explain it coherently.

Sample answer: Two-way data binding is one of four types of binding in Angular, along with property binding, event binding, and string interpolation. A component (model) and its HTML template can share data with this binding. So, any data altered on the model automatically and instantly updates on the template, and vice versa. This ensures the  HTML template and TypeScript code are always up to date. 

6. What is view encapsulation in Angular?

Why are they asking? They want to know if you can isolate your design components at work without impacting the rest of the application.

Sample answer: View encapsulation defines how a component’s template and styles impact the program or vice versa. In Native encapsulation, the component does not inherit styles from the main HTML, but with Emulated, it will. When you select the third encapsulation method, None, component styles repeat to the main HTML. The default approach is typically Emulated.

7. What is RxJS in Angular?

Why are they asking? RxJS is a powerful built-in library that allows Angular to handle async tasks. 

Sample answer: RxJS stands for Reactive Extensions for JavaScript. These allow reactive programming by enabling the use of observables. When you want to compose asynchronous and callback-based code in Angular, you’ll use the RxJS library in Angular. Many APIs use this functional, reactive style. The availability of the RxJS library from the outset in Angular is one of its advantages for developers. 

8. What are pipes in Angular?

Why are they asking? Pipes are very useful in template expressions to transform data (e.g., currency amounts or dates) and return it transformed in the application. 

Sample answer: The pipe in Angular takes in data and transforms it into your desired output. You can add any pipe parameters to tweak how the output data displays. Developers can also chain or customise pipes in Angular to achieve their goals. 

9. What are lifecycle hooks in Angular?

Why are they asking? It’s important that you can talk intelligently about the entire lifecycle of Angular.

Sample answer: Once you create a component in Angular, its lifecycle begins. During this period, until the component is destroyed, Angular hooks allow you to check on parts or trigger changes at specific phases. 

In order, the main lifecycle hooks are: 

• ngOnChanges: Method for changing more than one input property on the component 

• ngOnInit: Following ngOnChanges, initialises the component and sets the input properties

• ngDoCheck: The third lifecycle hook detects and acts on any changes Angular can’t or won’t detect on its own

• ngOnDestroy: This lifecycle hook allows you to provide custom code cleaning and the ability to remove event handlers before the component is destroyed.

10. What is Bootstrap, and how is it embedded in Angular?

Why are they asking? Bootstrap is what makes reactive design possible. Since responsiveness is critical to a web page or app’s success, your employer wants to know you can make it happen.

Sample answer: Bootstrap collects HTML, CSS, and JavaScript tools to help developers create and build responsive web pages and applications. You can embed Bootstrap’s library into an Angular application via a public Content Delivery Network (CDN) or by installing it into your project folder using Node Package Manager (NPM) 

Angular bootstrapping can be manual or automatic, depending on how much control developers want in initialising the Angular app.

Learn more about Angular

Another way to successfully launch your career as an Agile developer is to learn more about the Angular framework. You might consider taking courses or a specialisation on Coursera to learn more about Angular, such as Single Page Web Applications with AngularJS, and build job-ready skills to enter an entry-level Agile developer position.