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Angular JS Questions And Answers

Published On: June 24, 2022


In the world of application development, Angular is a popular front-end JavaScript framework. One of the most sought-after skills in order to get a job, but it’s also one of the trickiest to master from an interview point of view. In light of this, we have compiled a list of important interview questions and answers for Angular that will guide you to succeed in your “Angular interviews” with flying colors.

Top AngularJS Interview Questions 2022

1. What is Angular? / How well do you know Angular?

Angular is developed and maintained by Google and it is one of the most prevalent frameworks of JavaScript . It is a TypeScript-based front-end web framework. Its features of “code reuse and maintenance” make it ideal for building enterprise-level web applications. Many components of frontend web applications can be handled by this framework, including HTTP requests, routing and layout. It is a comprehensive framework in this regard.

2. What are the Angular framework’s core technologies?

Angular is a Google-developed front-end JavaScript framework. Angular itself employs a variety of technologies for a variety of reasons, including speeding up certain tasks and making it easier for developers to create applications with it. ” TypeScript”, a superscript of JavaScript, is used by Angular. As a result, TypeScript can be written in any JavaScript. However, TypeScript enables us to write JavaScript as a strongly typed language, and we can also define our own types, making it much easier to detect bugs. Developers can better handle asynchronous operations because RxJS is used.

3. What are some of Angular’s most powerful features?

Angular includes powerful features such as declarative templates, dependency injection, end-to-end tooling, and other best attributes that make the development process go more smoothly.

4. What is Angular’s primary function?

Angular is primarily used to develop dynamic, scalable, and quick web applications. Using Angular’s components and guidelines, we can build these applications with ease.

Angular began as Single-Page-Application(SPA) structure, and it now facilitates user-specific dynamic content via dependency injection. It offers a platform for the simple development of web-based applications and gives front end developers the ability to curate cross-platform applications. YouTubeTV is the most well-known application of Angular.

5. What are the primary benefits of using Angular?

Here is a list of the greatest benefits of utilising the Angular framework:

  • Angular allows for two-way data binding.
  • It pursues the MVC architecture style.
  • It is compatible with both static and Angular templates.
  • It enables the addition of a custom directive.
  • Additionally, it endorses RESTful services.
  • In Angular, validations are justified.
  • Angular supports client-server communication.
  • It offers dependency injection support.
  • It offers amazing tools such as Event Handlers and Animation, among others.

6. What exactly are templates in Angular?

In Angular, templates are composed of elements and attributes specific to Angular. These are composed with HTML and then coupled with data gained from the model and controller. This information is then deemed to offer the user a dynamic perspective of the application.

7. In Angular, what are decorators?

Decorators are design patterns or methods that define the behaviour of Angular features. They are often used to make changes to a class, service, or filter before they are deployed. Angular endorses four different types of decorators:

  • Parameter Decorators
  • Method Decorators
  • Class Decorators
  • Property Decorators

8. What is an Angular Annotation?

Annotations are the “only” metadata set of a class that uses the Reflect Metadata library in Angular. They are employed to construct an “annotation” array.

9. Why was Angular created as a framework for the client-side?

Before Angular was introduced, web developers utilised VanillaJS and jQuery to create dynamic websites. Afterward, when enhanced features and functions made the websites quite sophisticated, it became hard to maintain the code. In addition, jQuery did not provide any data management facilities across all views. The essence for a client-side framework like Angular was noticeable as it simplifies the lives of developers by managing the separation of concerns and dividing code into smaller pieces of information (components).

Using client-side frameworks such as Angular, developers can design new incredible web applications such as Single-Page-Application. These applications could also be devised using VanillaJS, but the development process slows down and timeframe will increase

10. Why is Angular more popular than other frameworks? What are the benefits of Angular compared

Because of the following characteristics, Angular is favoured over other frameworks:

  • Angular’s out-of-the-box built-in features include state management, routing, the RxJS library, HTTP services and dependency injection, among others. Therefore, developers do not need to search separately for the aforementioned features.
  • Angular’s user interface is declarative. As a declarative language, HTML is used to render an application’s user interface. It is significantly simpler to use than JavaScript
  • Google provides ongoing development and maintenance for Angular and Google has a long-term plan to continue providing support for Angular.

11. Why does Angular employ the AOT compiler?

An Angular application is composed of multiple components and their respective HTML templates. Due to these Angular components and templates, browsers are unable to directly comprehend them. Therefore, Angular applications must be compiled prior to browser execution. Therefore, AOT compilers are necessary.

12. In Angular, what exactly is JIT?

JIT stands for Just-In-Time compiler in Angular. The JIT compiler supports dynamic translation or run-time compilation, which is a method for implementing programming code that includes compilation during the program execution at run time as opposed to before execution.

13. What are Angular directives?

In Angular, a directive is a class that is decorated with the @Directive guideline. Each directive has its own behaviour and can be imported into diverse application elements. Three types of directive are supported by Angular. They are

  • Structural directive
  • Component directive
  • Attribute directive

14. What exactly is data binding? Angular uses which type of data binding?

Data binding is a concept that enables any internet user to modify Web page aspects through the use of a Web browser. It employs dynamic HTML and does not necessitate any complex scripting or programming. Data binding is used in web pages with interactive tools such as forms, formulas, tutorials, and contests. When pages contain a large amount of data, iterative display of a webpage helps make binding more comfortable.

The two-way binding is used by Angular. Any modifications to the user interface are represented in the model state. User Interface state reflects any change in the model state. The framework can now connect the DOM to the Model data through the controller. This methodology, however, has an impact on performance because every alteration in the DOM must be tracked.

15. What are Single Page Applications (SPA)?

Single-page applications are web applications that only load once and have advanced functionality that are simply additions to the user interface. It does not load the latest HTML pages to display the new page’s subject matter, which is generated dynamically. This is facilitated by JavaScript’s power to alter the DOM elements on the existing page. A SPA approach is quicker, resulting in a more rich user experience.

16. What exactly are filters in Angular? Please name a few.

Filters are being used to format and display an expression to the user. They can be utilised to view templates, controllers, and services. The following are some built-in filters.

date – Formats a date according to a predefined format.

filter – Choose a subset of an array’s items.

Json – Create a JSON string from an object.

limitTo – Reduces an array or string to a stipulated number of elements or characters.

lowercase – Shifts the case of a string to lowercase.

17. In Angular, what is view encapsulation?

View encapsulation specifies whether or not the template and styles defined within the component can impact the overall application. Angular offers three encapsulation methods:

Emulated: Styles from the main HTML are emulated and propagated to the component.

Propagated: Styles from the main HTML do not pass through to the component.

None: The Styles of the components are propagated to the primary HTML andhence all the components of the page get notified..

18. What precisely are controllers?

AngularJS controllers are in charge of the data control in AngularJS applications. They’re standard JavaScript Objects. The application controller is defined by the ng-controller directive.

19. In Angular, what do you mean by scope?

In Angular, the HTML/ view, and the JavaScript/controller are connected by scope. It is, as expected, an object with the methods and properties that are provided. Scope is accessed by both the controller and view. In Angular, you specify the $scope object as an argument when constructing a controller.

20. In Angular, what is String Interpolation?

String interpolation is the method of one-way data binding that distributes data from TypeScript code to an HTML view, which are denoted by Double curly braces. This template expression permits the component’s data to get displayed in the view.

{{ data }}

21. In Angular, what are Services?

Angular Services are used by various components to accomplish operations. Data and image retrieval, network connectivity, and database management are examples of these jobs. They handle all of the component’s operating tasks and prevent rewriting code. A service can be created once and then injected into all of the entities that use it.

22. What are Promises and Observables in Angular?

Both promises and observables in Angular are linked with asynchronous events.

Promises are associated with one event at a time and result in one value whereas observables are associated with a series of events over time and result in multiple values.

  • Promises go into effect right once they’re created and can’t be stopped.
  • Observables are only performed when the subscribe() method is employed. They assist in the execution of tasks such as filter, forEach, and retry, among others. Errors are received by the subscribers for actions. They stop receiving new data when the unsubscribe() method is performed.

23. How do you differentiate between Angular and AngularJS?

These are the differences between Angular and AngularJS

ArchitectureDirectives and components are made useModel-View-Controller or MVC model is supported
Expression Syntax() for binding an event whereas [] for binding a propertyTo bind a property or an event, proper “ng” directive is used by professionals
LanguagesTypescript languageJavascript language
Mobile SupportMobile support is offeredAngularJS does not provide mobile support
Routing@RouteConfig{(…)} is used$routeprovider.when() is used
Dependency InjectionHierarchical dependency injection, together with a unidirectional tree-based change direction is adoptedIt does not adopt dependency injection
StructureSimple structure to facilitate professionals to develop and maintain large applications easilyComparatively less manageable

24. What are the new Angular10 features?

Older editions of Angular enabled TypeScript 3.6, 3.7, and even 3.8, but older versions are no longer supported. Now, with the release of Angular 10, TypeScript was upgraded to TypeScript 3.9.

Unknown property bindings or element names in templates are now logged as “errors,” rather than “warnings.”

  • When you use the ng new command to establish a new workspace, you can choose to use a stricter project setup.

ng new—strict

  • NGCC features are combined with a program-based entry point finder.
  • Routing of URLs has been updated
  • There are various deprecated APIs in Angular 10.
  • This release of Angular 10 includes a number of bug fixes, the most notable of which are the compiler’s avoidance of “undefined expressions” and the core’s avoidance of a “migration error” when a nonexistent symbol is imported.
  • For new projects, the default browser configuration has been upgraded to outperform older and less utilised browsers.

25. Describe the lifecycle hooks in Angular ?

Every component of Angular has a lifecycle. Angular performs the creation and rendering of these components and also destructs them before eliminating them from the DOM. This is made possible with the help of lifecycle hooks. The list of hooks are mentioned below :

  1. ngOnInit() – Initiate the directive/component after Angular displays the data-bound properties first and sets the component’s input properties
  2. ngOnChanges() – Gives response when Angular sets/resets data-bound input properties.
  3. ngDoCheck() – Identify and react upon changes that Angular couldn’t or won’t detect on its own.
  4. ngAfterContentInit() – Gives response after Angular projects external content into the component’s view.
  5. ngAfterViewChecked() – Respond after Angular verifies the directive’s views and child views.
  6. ngAfterContentChecked() – Respond after Angular verifies the content predicted into the directive.
  7. ngAfterViewInit() – Gives response after Angular initiates the component’s views and child views.
  8. ngOnDestroy – Cleanup just before Angular destructs the directive/component.

26. What constitutes Template statements?

In HTML, template statements are attributes or methods that respond to user events. With the template declarations, the application you design or are working on can increase customer engagement by allowing them to submit forms and view interactive content.

As an example

button (click)=”deletePlayer()”>

Delete player</button>

deletePlayer is the template used here. Whenever the user hits the button, the method is invoked.

27. What are the distinctions between AOT and JIT?

Ahead of Time (AOT) compilation translates your code while it is being built, rather than waiting for the browser to download and run it. This confirms that the web browser furnishes the page more speedily. Comprise —aot parameter with the ng build or ng serve commands to ensure AOT compilation.

The Just-in-Time (JIT) compilation method performs the conversion of computer related code to machine code while it is being accomplished or run. Dynamic compilation is another name for it. JIT compilation is availed by default, When ng build or ng serve CLI commands are applied.

28. What exactly is Bootstrap? How does it integrate with Angular?

Bootstrap is a robust framework. It’s a set of CSS, HTML, and JavaScript tools for generating and developing dynamic web pages and apps.

The bootstrap library can be included into your programme in two methods..

Content Delivery Network Angular Bootstrap

It is a public network that circulates the content to users. It allows you to load CSS and JavaScript resources from its servers remotely.

Angular Bootstrap through NPM 

Another option for incorporating Bootstrap into your Angular application is to use NPM to put it into your project directory (Node Package Manager).

npm install bootstrap

npm install jquery

29. What is the difference between eager and lazy loading?

The default module-loading approach is eager loading. Eager loading feature modules are loaded before the programme starts. This is generaly designated for applications that are not much larger.

When there is a demand, lazy loading constantly loads the feature modules. This speeds up the application. It is used in large sized applications where all the modules are not needed initially.

30. What are the elements of the Angular framework?

The elements of angular are stated below :

Components: A component can manage many views, each of which represents a different section of the screen. All Angular applications require a root component. All of the components comprise the application’s logic, which is described as a class, with the class’s primary function being to interact with the view via an API of functions and properties.

Data Binding: The mechanism through which the different aspects of a template communicate with the component is known as data binding. The binding markup must be included to the HTML template so that Angular can recognize how the component and template are connected.

Dependency injection: It use DI to provide new components with the appropriate dependencies, primarily services. The function Object() { [native code] } parameters of a component educate Angular about the multiple services that the component requires, and DI gives a means to provide the new class instances the dependencies they require.

Directives: Because Angular templates are dynamic, directives enable the framework to understand how to alter the DOM while displaying the template.

Metadata: With the help of decorators, classes have metadata associated with them so that Angular knows how to handle the class.

Modules: A module, often known as a NgModule, is a logically ordered unit of code with a single workflow. The root module is present in all Angular apps, and the majority of them have many modules.

Routing: The Angular router interprets a browser’s URL to provide a client-generated interaction and view. This router is coupled to page links so that when the user clicks on one, Angular will proceed to the application view.

Services: Services are a broad category that include anything from functions and values to features that are important in Angular apps.

Template: Each component’s view is associated with a template, and an Angular template is a sort of HTML tag that enables Angular to figure out how to draw the component.


The frequently asked questions of both basic and advanced levels of angular are discussed above to guide you to get through the angular interview brilliantly and kick start a productive career.

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