Top 20+ Interview Questions and Answers for AngularJS (2023)

If you are someone who is looking for a fruitful career in the tech industry or has already secured an interview, it is time to hone your answering skills. When companies look to hire good AngularJS developers, they look for in-depth knowledge of the subject. Even though every interview and interviewer is different, there are a few questions that are very popular among interviewers to check your skills. We have compiled a list of AngularJS interview questions and answers for both freshers and experienced to help you crack that interview.

So the interview is near, don’t worry, in this article, we will discuss the Top 20+ most frequently asked AngularJS Interview Questions.

Let’s begin!

AngularJS Interview Questions For Freshers

Question 1. What is AngularJS?

Answer – AngularJS is an open-source JavaScript-based structural framework, built for developing large-scale, enterprise-level, dynamic, single-page web applications.

AngularJS lets you use HTML as its main template language and uses its syntax for representing the application’s components such as directives.

AngularJS is used for writing client-side logic with the features of JavaScript and MVC architecture. AngularJS creates easily maintainable, cross-browser-compatible enterprise-level web applications.

Question 2. What is a single-page application in AngularJS?

Answer – Single Page Application (SPA) is a web application or a website that dynamically interacts with its users. AngularJS performs navigation without refreshing the entire page.

Question 3. How can you integrate AngularJS with HTML?

Answer – Using the <script> tag in the HTML head section, we first bind the AngularJS library to the HTML page and then bootstrap the AngularJS app using the ng-app directive as below.

<html>
   <head>
      <script src = "https://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js"></script>
      <!--Other libraries-->
   </head>
   <!--ng-app attribute to bootstrap AngularJS application-->
   <body ng-app = "myApp">
       <!--Web page elements-->
   </body>
</html>

Question 4. What are the key features of AngularJS?

Answer – The main features of AngularJS are listed below:

Applications made with AngularJS can be tested.
Data-binding − Data binding makes it easier to synchronize data between the model and view components in the framework.
Services − Many built-in services are available with AngularJS, such as $http, which helps make XMLHttpRequests and AJAX requests.
Scope − Between the view and the controller, AngularJS offers unique objects called Scope that relate to the models.
Filters − AngularJS includes various built-in filters as well as the ability to construct custom filters for subsetting array items and filtering based on specified conditions.
Directives − Directives are used to extend HTML elements and DOM elements’ behavior. A prefix ng tells the compiler what specified behavior is to be attached to the DOM element.
Routing − AngularJS supports Routing which helps in switching views based on any condition.
MVC pattern − The Model-View-Controller pattern (MVC) is followed by AngularJS and helps allocate the responsibilities appropriately. The model manages the application data. Views display the application data and the controllers help in implementing the application logic by acting as an interface.
Dependency Injection − Dependency injection is one the main key feature of AngularJS. This feature facilitates applications’ development, maintenance, and testing by defining interactions and resolving dependencies between various components.

Question 5. What is the Data Binding process?

Answer – Data binding is the automatic syncing of data between the view and the model components. AngularJS uses ngBind and ngModel in directives to achieve this. This ensures that the view synchronizes with the model at all times.

Data binding has two ways: One-way and Two-way data binding

In one-way data binding, changes in the model are reflected in the view but changes in the view will not reflect in the model. It is unidirectional. Either you can bind the data from view to component or from component to view.
Whereas, the two-way data binding works both ways. When the model is updated, it is reflected in the view and vice-versa.

Question 6. Explain $scope in AngularJS.

In AngularJS, $scope is used when there is dependency injection, and scope is used for directive linking. Scope binds the view with the controller and $scope helps in the interaction between the application controller and the view.

Question 7. What do you mean by services in AngularJS?

Answer – Services are singleton objects that perform the tasks associated with them. AngularJS offers many different in-built services to interact with each other and developers can also create custom services.

For example, XMLHttpRequests are made using the $https: service (Ajax calls). Services are only created once in an application.

Question 8. What is AngularJS Expression? Explain the key difference between angular expressions and JavaScript expressions.

Answer – Angular expressions are code snippets that are placed in binding such as {{ expression }}

Expressions in JavaScript and AngularJS vary mostly in the following ways:

Context: In JavaScript, expressions are evaluated against the global window, while AngularJS expressions are evaluated against a scope object.
Forgiving: In Angular expression, evaluation is forgiving to null and undefined but in JavaScript expression, undefined properties generate TypeError or ReferenceError.
Control Flow Statements: In AngularJS, no control flow statements can be used such as loops, exceptions, or conditionals. While in JavaScript expressions control flow statements are allowed.
Filters: Filters can be used with AngularJS expressions but in JavaScript, expression filters do not work.
Function Declaration: In AngularJS, function declarations are not allowed. While in JavaScript expressions function declarations are allowed.

Question 9. What are directives? Name some of the most commonly used directives in AngularJS applications.

Answer – Directives are used to extend HTML elements and DOM elements’ behavior. Through a prefix ng, it tells the compiler what specified behavior is to be attached to the DOM element. AngularJS has built-in directives which can also be used to build user-defined directives. The built-in directives are

ngApp – It is the most important directive and is used to mark the start of the AngularJS app to the AngularJS HTML compiler. This is to be written first before any other directives.
ngBind – It is used to bind model variables with HTML controls and HTML tags
ngModel – ngModel directive is used in HTML controls like <input type=’text’/>. It is used in data binding because it provides a binding behavior between values.
ngRepeat – It is used to repeat HTML statements
ngClass – It is used to add or remove CSS classes on HTML elements
ngInit – ngInit is used before initializing application data variables

Question 10. Explain templates in AngularJS.

Answer – Templates are HTML files with AngularJS attributes and directives. In Angular, the model and controller work together with the templates to change the view that the user sees in their browser.

These can either be multiple views on a single page using “partials” or a single file (like index.html).

Question 11. Can there be two ng-app for a single angular application?

Answer – No, as the ng-app directive tells the AngularJS application that it is the root element. If there are more than one ng-app directives in the HTML file the first appearance will be used.

Question 12. Explain the purpose of interpolation in AngularJS.

Answer – Interpolation refers to the phenomenon of binding data by embedding expressions to the attribute and text nodes. The compiler does the task of matching the text and the attributes during the compilation. Behind the scenes, AngularJS uses $interpolate built-in service to verify if there is any markup having embedded expressions and if found then they are updated and registered in the form of watches.

Question 13. Define $rootScope in the AngularJS application.

Answer – In AngularJS, $rootScope refers to the scope object created on the DOM element containing the ng-app directive meant for bootstrapping the AngularJS application. This object is available across the whole AngularJS application. There can be only one $rootScope object in an application and all the scopes are children of the $rootScope object.

Question 14. Differentiate between ng-if and ng-show directives.

Answer – The ng-if directive does not render the DOM element portion if the condition specified is not satisfied. Here, the scope of the element would be destroyed if that is not rendered.

The ng-show directive on the other hand renders the DOM element but hides the display (applying the ng-hide class on that DOM element) if the condition specified within it is not satisfied.

Difference Between ng-if And ng-show Directives — **ng-if vs. ng-show**

Question 15. Describe how e2e testing works for AngularJS apps.

Answer – E2e testing is testing the app from start to finish and determining whether all components are working together or not. e2e testing acts as a safety net that catches issues related to integration and flow in the app. Protractor is a NodeJS app built by the AngularJS team to help developers simulate user interactions and test the app.

Question 16. What is an AngularJS module?

Answer – A module in AngularJS is like a container for all the components like a controller, filters, services, directives, etc, be it AngularJS core or third-party components.

An AngularJS module can be created by calling angular.module() method

Question 17. How to validate data in AngularJS?

Answer – Form filling and validation are facilitated by AngularJS. We can use flags like $dirty and $invalid to perform validations in an easier way. We can use novalidate with a form declaration to disable browser-specific validation.

Errors can be tracked using the following:

$dirty − shows that a value has changed.
$invalid − shows that the value entered is invalid.
$error − shows the exact error.

Question 18. Using core AngularJS functionality, list 3 ways to communicate between modules.

Answer – Well, some of the common ways to communicate between modules using AngularJS functionalities include using services and events. We can also communicate by assigning models on $rootScope. Apart from this, we can communicate directly between controllers by using $parent, $$childHead, $$nextSibling, ControllerAs, etc.

Question 19. How to set, get, and clear cookies in AngularJS?

Answer – $cookies.put() method is used to set the cookies.

$cookies.get() method is used to get the cookies.

$cookies.remove() is used to remove cookies in AngularJS.

Question 20. State some of the common Angular Global API functions.

Answer – Some commonly used Angular Global API functions are as follows:

angular.uppercase: Converts string to uppercase.
angular.lowercase: Converts string to lowercase.
angular.isString: Returns true if the reference is of type string.
angular.isNumber: Returns true if the reference is of type number or numeric value.
angular.isDate: Returns true if the value is a date.
angular.isArray: Returns true if the reference is an array.
angular.isFunction: Returns true if the reference is a function.
angular.isObject: Returns true if the reference is an object.

Question 21. When the scope is terminated, it fires two “destroy” events. What are they?

Answer – The two “destroy” events fired on scope termination are $destroy and jqLite / jQuery event “$destroy”. The former is associated with components like link functions or controllers and the latter is associated with the removal of the nodes which may happen without scope teardown.

These are just a few questions that you should have answers ready for apart from these basic AngularJS interview questions:

Define AngularJS and its features
Define Scope
How to boot AngularJS
What is SPA, etc?

These are some most common AngularJS interview questions and answers asked. Apart from these, there are several Web Developer Interview coding Questions and Answers that you can be asked including questions about your personal interests and experiences. The interviewer tries to evaluate your technical skills as well as your abilities as an employee, as a team member, and as an individual. So you should also focus on sharpening your interpersonal skills as well before your interview along with your technical skills.