
AngularJS Interview Questions and Answers
Navigating the competitive landscape of IT job placements requires thorough preparation and a deep understanding of the industry’s most sought-after skills. AngularJS, a prominent JavaScript framework, has emerged as a critical competency for aspiring developers seeking to excel in the dynamic world of web development. To help you gain a competitive edge, we’ve compiled a comprehensive collection of frequently asked AngularJS interview questions and their detailed answers, prepared by experienced AngularJS professionals.
Embark on your journey to confidently face AngularJS interview challenges and secure rewarding job opportunities. This meticulously crafted resource aligns with the expectations of leading multinational companies, providing you with the knowledge and confidence to showcase your expertise and make a lasting impression. Whether you’re a beginner or an experienced developer, these insightful AngularJS interview questions and answers will guide you through the intricacies of AngularJS and empower you to ace your upcoming interview.
Best AngularJS Interview Questions and Answers
Here is the list of 50+ most frequently asked AngularJS Interview Questions and Answers in technical interviews. These Angular JS questions and answers are suitable for both freshers and experienced professionals at any level.
So, dive into this treasure trove of AngularJS interview questions and answers, and emerge as a frontrunner in the highly sought-after field of web development.
1. What is AngularJS and what are its key features?
Ans: AngularJS is a JavaScript-based open-source front-end web application framework developed and maintained by Google. Its key features include two-way data binding, dependency injection, modular architecture, and the use of directives.
2. What are the benefits of using AngularJS?
Ans: AngularJS offers improved code organization, increased productivity, and enhanced testability. The two-way data binding feature reduces the need for boilerplate code, making it easier to maintain and scale applications.
3. What are the challenges of using AngularJS?
Ans: Common challenges include a steep learning curve for beginners, performance issues in complex applications, and the need for careful management of scopes to prevent potential memory leaks.
4. What is the future of AngularJS?
Ans: While newer frameworks like Angular and React have gained popularity, AngularJS still plays a vital role in maintaining existing applications. Its future involves continued support for legacy projects, but developers are encouraged to explore newer versions for greenfield projects.
5. How does AngularJS compare to other JavaScript frameworks, such as React and Vue.js?
Ans: AngularJS follows a more opinionated and comprehensive approach, while React and Vue.js offer more flexibility. AngularJS includes built-in features like two-way data binding and dependency injection, simplifying certain tasks compared to React and Vue.js.
6. Define Scope in AngularJS.
Ans: Scope in AngularJS is an object that refers to the application model. It acts as a context for evaluating expressions and consists of properties and methods, forming the binding between the HTML (view) and the JavaScript (controller).
7. What is scope inheritance? How does it work?
Ans: Scope inheritance is the mechanism by which child scopes inherit properties and methods from their parent scope. Any changes made to the child scope do not affect the parent scope, ensuring a clear separation of concerns.
8. What is scope isolation? How does it work?
Ans: Scope isolation involves creating a new scope that is not inherited from its parent. This is achieved using directives like ng-controller
and ng-repeat
. Isolated scopes prevent unintentional interference between parent and child scopes.
9. What is the difference between scope prototypal inheritance and scope chain inheritance?
Ans: Scope prototypal inheritance refers to the mechanism where child scopes inherit properties and methods from their parent scope via the prototype chain. Scope chain inheritance involves the linear structure of scopes, and any changes in child scopes directly affect the parent scope.
10. How can you create a new scope in AngularJS?
Ans: In AngularJS, there are two primary methods for creating a new scope:
- Using theÂ
$scope.$new()
 method: This method is used to create a new child scope of the current scope. The child scope inherits all the properties of the parent scope, but it also has its own private properties. This allows you to isolate the child scope from changes in the parent scope. - Using directives: Certain directives in AngularJS automatically create new child scopes. For instance, theÂ
ng-controller
 directive creates a new child scope for the controller function it references.
11. How can you destroy a scope in AngularJS?
Ans: Scopes are automatically destroyed by AngularJS when they are no longer needed or when their associated DOM elements are removed. However, you can manually destroy a scope using the $destroy
method.
12. What are directives?
Ans: Directives in AngularJS are markers on a DOM element that tell AngularJS’s HTML compiler ($compile
) to attach a specific behavior to that element or even transform the DOM structure.
13. What are the different types of directives?
Ans: There are three types of directives in AngularJS:
- Element directives: They modify the DOM element.
- Attribute directives: They modify the appearance or behavior of an element.
- CSS class directives: They conditionally apply CSS classes to elements.
14. How do you create a custom directive?
Ans: To create a custom directive, use the directive
function. This function allows you to define the directive’s behavior, including its template, controller, and link function.
15. How do you use directives to manipulate the DOM?
Ans: Directives manipulate the DOM by providing custom behavior or by modifying the element’s structure. This is achieved through the directive’s link function, where you can access and manipulate the DOM element.
16. What is the difference between directives and components?
Ans: While both directives and components provide modularization and reusability, components are a more specialized and structured form of directives. Components have a defined lifecycle, encapsulate their own behavior, and encourage the use of controllers.
17. Explain the data binding process in AngularJS.
Ans: Data binding in AngularJS establishes a connection between the model and the view, ensuring that any changes in the model are reflected in the view and vice versa. This process is categorized into two types: one-way and two-way data binding.
18. What are the different types of data binding?
Ans: There are two types of data binding in AngularJS:
- One-way data binding: Changes in the model update the view or vice versa.
- Two-way data binding: Changes in the model automatically update the view, and changes in the view automatically update the model.
19. How do you use data binding to update the DOM?
Ans: Data binding in AngularJS is achieved through expressions, which are enclosed in double curly braces ({{ expression }}
). These expressions are evaluated and the result is automatically updated in the DOM.
20. What are the limitations of data binding?
Ans: While data binding simplifies development, it can introduce performance issues in large applications. Excessive use of two-way data binding can lead to a complex and hard-to-maintain codebase.
21. Explain the purpose of interpolation in AngularJS?
Ans: Interpolation is a way to bind expressions to the content of HTML elements. It involves using double curly braces ({{ expression }}
) to embed dynamic values into the HTML.
22. How do you use interpolation to display data in the view?
Ans: Interpolation is used within HTML elements to display dynamic data. For example: <p>Hello, {{ name }}!</p>
.
23. What are the limitations of interpolation?
Ans: Interpolation is limited to displaying simple values and expressions. Complex logic or operations are better handled using other mechanisms, such as directives or controllers.
24. What is an AngularJS module?
Ans: An AngularJS module is a container for different parts of an application, including controllers, services, filters, directives, and more. It helps organize and structure the codebase.
25. How do you create an AngularJS module?
Ans: Use the angular.module
method to create a module. For example:
var myApp = angular.module('myApp', []);
26. What is the purpose of modules?
Ans: Modules provide a way to organize and structure AngularJS applications. They allow for better code separation, reusability, and maintainability.
27. How do you use modules to organize your code?
Ans: Divide your application into distinct modules, each responsible for a specific feature or functionality. Use dependency injection to link these modules and create a modular and scalable architecture.
28. Differentiate between expressions of AngularJS and JavaScript.
Ans: AngularJS expressions are evaluated in the context of AngularJS, allowing for the use of AngularJS-specific features. JavaScript expressions, on the other hand, are evaluated in the context of standard JavaScript.
29. What are the different types of expressions?
Ans: AngularJS supports regular expressions and a subset of JavaScript expressions. However, it has its own set of filters and functions that can be used within expressions.
30. How do you use expressions to evaluate data?
Ans: Expressions are embedded within double curly braces ({{ expression }}
) in the HTML. AngularJS evaluates these expressions and updates the DOM accordingly.
31. What are the limitations of expressions?
Ans: AngularJS expressions have limitations in terms of complexity and cannot contain statements, loops, or exception handling. Complex logic is better suited for controllers or services.
32. What is a controller in AngularJS?
Ans: A controller in AngularJS is a JavaScript function that handles the business logic of an application. It manages the data and behavior of the application, linking the model and the view.
33. How do you create a controller?
Ans: Controllers are created using the controller
method of an AngularJS module. For example:
myApp.controller('MyController', function($scope) {
// Controller logic here
});
34. What is the purpose of controllers?
Ans: Controllers are responsible for handling user input, updating the model, and interacting with services. They play a crucial role in separating concerns within an AngularJS application.
35. How do you use controllers to handle user interactions?
Ans: Controllers are attached to the HTML using the ng-controller
directive. They define functions and properties that can be accessed within the associated view, allowing for interaction and data manipulation.
36. What are filters in AngularJS?
Ans: Filters in AngularJS are functions that can modify the value of an expression or a data item for display purposes. Filters can be used in view templates, controllers, or services to format, filter, sort, or transform data. AngularJS provides a set of built-in filters, such as uppercase, lowercase, currency, date, number, orderBy, and filter, that can handle common data manipulation tasks. You can also create your own custom filters by using the $filterProvider service. They can be applied to expressions using the |
symbol.
37. How do you create a custom filter?
Ans: Custom filters are created by registering a new filter function using the filter
method of an AngularJS module. For example:
myApp.filter('customFilter', function() {
// Filter logic here
});
38. How do you use filters to format data?
Ans: Filters are applied to expressions within the HTML using the |
symbol, followed by the filter name. For example:
<p>{{ someData | customFilter }}</p>
39. What are the limitations of filters?
Ans: While filters are powerful for simple data transformations, complex logic is better handled in controllers or services. Overusing filters can impact performance.
40. What are services in AngularJS?
Ans: Services in AngularJS are singleton objects that perform specific tasks, such as sharing data between controllers, handling business logic, or interacting with external APIs.
41. How do you create a service?
Ans: Services are created using the service
method of an AngularJS module. For example:
myApp.service('myService', function() {
// Service logic here
});
42. What is the purpose of services?
Ans: Services promo code reusability by encapsulating functionality that can be shared across different parts of an application, such as controllers.
43. How do you use services to share data between controllers?
Ans: Services act as a bridge between controllers by storing and providing access to shared data. Controllers can inject the service and use its methods or properties to communicate.
44. What are components in AngularJS?
Ans: Components are a more specialized and structured form of directives in AngularJS. They encapsulate a piece of functionality, including its template, controller, and styles.
45. How do you create a component?
Ans: Components are created using the component
method of an AngularJS module. For example:
myApp.component('myComponent', {
// Component configuration here
});
46. What is the purpose of components?
Ans: Components provide a modular and reusable way to encapsulate functionality. They have a defined lifecycle and are considered a best practice for building AngularJS applications.
47. What is routing in AngularJS?
Ans: Routing in AngularJS is a mechanism for navigating between different parts of a single-page application (SPA). It allows for dynamic loading of views and updating the URL without a full page reload.
48. How do you set up routing in your application?
Ans: Routing is configured using the $routeProvider
service in AngularJS. You define routes, associate them with controllers and templates, and specify the URL mappings.
49. How do you use routes to navigate between different parts of your application?
Ans: Routes are defined using the ng-view
directive in the HTML, and navigation is achieved by clicking links or programmatically using the $location
service.
50. How do you test AngularJS applications?
Ans: AngularJS applications can be tested using various testing frameworks such as Jasmine, Karma or Protractor. Unit testing, integration testing, and end-to-end testing are common approaches. AngularJS also provides some testing utilities that can make testing easier and more convenient. Some of these utilities are:
- TestBed
- async
- inject
51. What are the different types of tests you can write for AngularJS applications?
Ans: The three main types of tests for AngularJS applications are:
- Unit tests: Testing individual components or functions.
- Integration tests: Testing how different components work together.
- End-to-end tests: Testing the complete application flow.
52. What are the benefits of testing AngularJS applications?
Ans: Testing ensures the reliability and maintainability of AngularJS applications. It helps catch bugs early in the development process, provides documentation, and ensures that changes to the codebase do not introduce regressions.
In conclusion,
Mastering AngularJS is essential for front-end developers looking to build dynamic and scalable web applications. These AngularJS interview questions and answers should serve as a valuable resource for aspiring developers preparing for AngularJS interviews. As the landscape of web development continues to evolve, staying abreast of the latest frameworks and best practices becomes increasingly crucial. What are your thoughts on the future of front-end development, and how do you envision the role of frameworks like AngularJS in shaping the next generation of web applications? Happy coding!