Angular is a popular JavaScript-based open-source web application framework that is used to build dynamic and scalable web applications. It is maintained by Google and is a successor to AngularJS. Angular has become one of the most popular front-end development frameworks used by developers across the world. In this blog post, we will discuss some of the commonly asked Angular interview questions along with their answers.
If you are preparing for an interview for an Angular developer position, you must be well-versed with the framework and its features. You should be able to answer technical questions related to Angular, JavaScript, and web development. Let us have a look at the Top 20 Angular Interview Questions and Answers.
20 Angular Interview Questions with Answers
What is Angular?
Angular is an open-source front-end web application framework that is used to build dynamic and scalable web applications. It is developed and maintained by Google and was first released in 2010. Angular allows developers to create powerful and complex applications using declarative templates, dependency injection, two-way data binding, and other advanced features.
What are the features of Angular?
The features of Angular include:
- Two-way data binding: This allows changes made in the UI to be reflected in the data model and vice versa.
- Dependency injection: This enables the creation of loosely coupled and testable components.
- Modular architecture: This allows applications to be broken down into smaller, reusable modules.
- Templates and directives: These provide an easy way to create and manipulate the DOM of an application.
- Routing and navigation: This allows for the creation of complex navigation structures within an application.
- Animations and gestures: This provides a way to create engaging and interactive user interfaces.
- Cross-platform development: This allows for the creation of applications that can run on a variety of platforms and devices.
What is TypeScript?
TypeScript is a typed superset of JavaScript that is used to build large and complex applications. It is used in Angular to add static type checking and class-based object-oriented programming features to JavaScript. TypeScript. provides features such as interfaces, classes, and modules that are not available in JavaScript. This makes it easier to write and maintain large codebases and catch errors at compile time rather than at runtime.
What is the difference between AngularJS and Angular?
AngularJS is an older version of Angular that was developed by Google in 2009. It uses JavaScript and has a different architecture compared to Angular. Angular, on the other hand, uses TypeScript and has a modular architecture. Angular also provides many advanced features that are not available in AngularJS, such as dependency injection, two-way data binding, and a component-based architecture.
What is the difference between a module and a component in Angular?
A module is a container for a group of related components, directives, and services. It is used to organize and separate the different parts of an application. Modules provide a way to define dependencies between different parts of an application and make them available for use in other parts of the application. A component, on the other hand, is a reusable building block that defines the UI and behavior of a part of an application. Components encapsulate the data and behavior of a part of an application and can be reused throughout the application.
What is a directive in Angular?
A directive is a reusable piece of code that is used to add behavior or manipulate the DOM of an application. Directives are used in Angular to extend the functionality of HTML elements. There are three types of directives in Angular: component directives, attribute directives, and structural directives. Component directives are used to create reusable UI components. Attribute directives are used to add behavior to existing HTML elements. Structural directives are used to manipulate the structure of the DOM.
What is the role of NgModule in Angular?
NgModule is a decorator in Angular that is used to define a module. It is used to group related components, directives, and services together and make them available for use in other parts of an application. NgModule also provides a way to configure and initialize the dependencies of an application.
What is the use of the ngFor directive in Angular?
The ngFor directive is used in Angular to iterate over a collection of items and generate HTML for each item in the collection. It is commonly used to display a list of items in an application. The ngFor directive takes an expression that evaluates to an array or an object, and generates a template for each item in the array or object.
What is the difference between ngIf and ngSwitch in Angular?
ngIf is a directive that is used to conditionally render a part of an application based on a Boolean expression. The ngIf directive removes or recreates a portion of the DOM based on whether the expression evaluates to true or false. This is useful for hiding or showing parts of an application based on a user’s actions or data.
ngSwitch, on the other hand, is a directive that is used to conditionally render a part of an application based on a switch expression. The ngSwitch directive evaluates an expression and matches it to a set of possible values. It then renders a template based on the matching value. This is useful for creating complex conditional logic in an application.
What is Angular CLI?
Angular CLI is a command-line interface for Angular that is used to generate and manage Angular projects. It provides a set of tools and features that make it easy to develop and deploy Angular applications. Angular CLI includes features such as generating components, services, and modules, running tests, and building and deploying applications.
What is a service in Angular?
A service is a reusable piece of code that is used to perform a specific task in an application. Services are used to encapsulate business logic and share data between different components in an application. Services can be used to perform tasks such as data retrieval, validation, and manipulation.
What is dependency injection in Angular?
Dependency injection is a design pattern used in Angular to manage dependencies between different components in an application. It is used to provide a way for components to access the services they need without creating tight coupling between them. Dependency injection allows for the creation of loosely coupled and testable components.
What is the difference between a template-driven form and a reactive form?
Template-driven forms are a type of form in Angular that are based on the HTML template of a component. They use two-way data binding to synchronize the data between the form and the component. Template-driven forms are easy to use and require less code than reactive forms, but they can be less flexible and harder to test.
Reactive forms, on the other hand, are a type of form in Angular that are based on a reactive programming model. They use a reactive form model to manage the data and behavior of the form. Reactive forms are more flexible and easier to test than template-driven forms, but they require more code to implement.
What is a route guard in Angular?
A route guard is a feature in Angular that is used to control access to routes in an application. Route guards are used to prevent unauthorized access to certain parts of an application or to perform authentication and authorization checks before allowing access to a route. There are several types of route guards in Angular, including CanActivate, CanDeactivate, CanLoad, and Resolve.
What is change detection in Angular?
Change detection is a feature in Angular that is used to detect changes in the data model of an application and update the UI accordingly. Change detection is an automatic process that is triggered by user events, asynchronous operations, or other changes in the data model. Angular provides several strategies for change detection, including default, onPush, and manual.
What is Angular Universal?
Angular Universal is a platform for server-side rendering of Angular applications. It allows for the creation of applications that can be rendered both on the server and the client, providing better performance, SEO, and accessibility. Angular Universal can be used to create progressive web applications (PWAs) and hybrid mobile applications.
What is lazy loading in Angular?
Lazy loading is a technique in Angular that is used to load parts of an application on demand, rather than loading everything at once. Lazy loading improves the performance of an application by reducing the initial loading time and only loading the components that are required by the user. This technique is especially useful for applications with large codebases or complex navigation structures.
What is ngZone in Angular?
ngZone is a service in Angular that is used to manage the execution of asynchronous tasks. It provides a way to run code outside or inside the Angular zone. The Angular zone is a context in which change detection and other Angular features are enabled. ngZone can be used to optimize the performance of an application by running expensive tasks outside the Angular zone.
What is a pipe in Angular?
A pipe is a feature in Angular that is used to transform data in a template. Pipes are used to format, filter, or sort data before it is displayed in the UI. Angular provides several built-in pipes, such as date, uppercase, lowercase, and currency. Custom pipes can also be created to meet specific application requirements.
What is NgRx in Angular?
NgRx is a library for state management in Angular applications. It is based on the Redux pattern and provides a way to manage the state of an application in a predictable and scalable way. NgRx can be used to create applications with complex data flows and a large number of components. NgRx provides features such as actions, reducers, and effects to manage the state of an application.
Conclusion
Angular is a powerful and popular front-end web application framework that is widely used in the industry. It provides a set of advanced features such as two-way data binding, dependency injection, and modular architecture that make it easy to build dynamic and scalable web applications.
If you are preparing for an Angular interview, it is important to be familiar with the framework and its features, as well as JavaScript and web development concepts. Hopefully, this blog post has provided you with some useful Angular interview questions and answers that will help you prepare for your next interview. Good luck!