Top Angular Interview Questions and Answers

If you are looking to interview candidates for a developer role using Angular, you may want to use some of these questions to test their knowledge and skills in Angular. In this article, we will discuss some of the top Angular interview questions and provide answers to help you better prepare for to interview candidates.

Introduction to Angular Interview Questions

Before we dive into the specific Angular interview questions, let’s introduce Angular and its key features.

What is Angular?

Angular is a popular JavaScript framework used to build dynamic web applications. It was created by Google in 2010 as AngularJS and later rewritten as Angular. Angular allows developers to write clean, maintainable, and scalable code using TypeScript.

Why is Angular popular?

Angular is widely used in the industry because it offers several benefits:

• It uses the Model-View-Controller (MVC) architecture to separate application logic from the User Interface (UI) logic.
• The code is testable, thanks to the built-in testing tools and the Angular CLI.
• It offers two-way data binding, which saves developers time and effort in managing the state of the application.
• It has a large community that provides support and resources for developers.

One of the main advantages of Angular is that it allows for the creation of Single Page Applications (SPAs). This means that the application loads only once and subsequent interactions with the user are handled through dynamic updates to the page, rather than requiring a full page reload. This results in a faster and more seamless user experience.

Another key feature of Angular is its use of directives, which allow developers to extend HTML with custom attributes and tags. This makes it easier to create reusable components and simplify the overall structure of the application.

Furthermore, Angular is known for its strong focus on code quality and maintainability. The framework provides a number of tools and best practices that help developers write clean, modular code that is easy to understand and maintain over time.

Finally, Angular has a large and active community of developers who contribute to the ongoing development and improvement of the framework.

Basic Angular Interview Questions

Beginners in Angular should be capable of answering the following basic Angular interview questions.

What are Angular components?

Angular components are the basic building blocks of an Angular application. They consist of three parts: template, class, and metadata. The template defines the user interface, while the class handles the component logic, and the metadata provides information about the component, such as its selector and dependencies.

Components are reusable and can be nested within other components to create complex user interfaces.

Explain data binding in Angular

Data binding is a mechanism in Angular that synchronizes the data between the component and the view. Angular supports four types of data binding:

• Interpolation binding: {{ expression }}
• Property binding: [property]="expression"
• Event binding: (event)="expression"
• Two-way binding: [(ngModel)]="expression"

What are directives in Angular?

A directive is a UI element in Angular that adds behavior to the HTML elements. There are three types of directives in Angular:

• Component directives
• Attribute directives
• Structural directives

Intermediate Angular Interview Questions

What is the difference between AngularJS and Angular?

AngularJS is the first version of Angular and was released in 2010. It uses JavaScript and follows the MVC architecture. Angular, on the other hand, uses TypeScript and is based on a component-based architecture. Angular also has better performance and a simpler learning curve than AngularJS.

Explain the role of dependency injection in Angular

Dependency injection is a design pattern in which the objects are passed their dependencies instead of creating them. In Angular, dependency injection is used to provide the dependencies to the components, services, and other objects. This allows for better code organization, easier testing, and increased flexibility.

How does change detection work in Angular?

Change detection is a mechanism in Angular that detects changes in the application state and updates the UI accordingly. Angular uses a hierarchical change detection mechanism that starts from the root component and propagates down the component tree.

Advanced Angular Interview Questions

What are the different types of decorators in Angular?

Decorators are used in Angular to modify or define the behavior of a class, property, method, or parameter. There are several types of decorators in Angular, such as:

• Class decorators, such as @Component and @NgModule
• Property decorators, such as @Input and @Output
• Method decorators, such as @ViewChild and @ContentChild
• Parameter decorators, such as @Inject and @Optional

Explain lazy loading in Angular

Lazy loading is a technique in Angular in which the large parts of the application are loaded only when needed. This can significantly reduce the initial loading time of the application, improve performance, and reduce the size of the application bundle.

How to optimize Angular application performance?

Performance is a critical aspect of any Angular application. To optimize Angular application performance, developers should follow these best practices:

• Use the OnPush change detection strategy.
• Avoid heavy computations in the templates.
• Minimize the application bundle size using lazy loading and tree shaking.
• Use Ahead-of-Time (AOT) compilation to reduce the application load time.
• Use server-side rendering (SSR) to improve the application’s initial rendering time.

Conclusion

In conclusion, these are some of the top Angular interview questions that candidates should be familiar with to excel in an Angular job interview.