Ace Your Angular JS Interview: 20 Commonly Asked Questions with Answers (2023)

Angular JS questions are crucial for interviews as they assess a candidate’s understanding of the framework’s concepts, principles, and best practices. By evaluating their knowledge of Angular JS, employers can ensure candidates possess the necessary skills to develop robust, efficient, and scalable applications using the framework.

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Here is the compilation of the top 20 commonly asked questions in interviews:

1. What exactly is AngularJS, and what are its main features?
   
   Google’s AngularJS is an open-source JavaScript framework.Its key features include two-way data binding, dependency injection, directives, modular architecture, and support for building single-page applications (SPAs).
   
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2. What is the distinction between one-way and two-way data binding in AngularJS?
   
   One-way data binding refers to the flow of data from the component to the view, where changes in the component update the view. Two-way data binding, on the other hand, allows for data to flow in both directions, meaning changes in the view can also update the component.
   
3. Explain dependency injection in AngularJS?
   
   Dependency injection is a design pattern used in AngularJS to manage dependencies between different components. It allows you to inject dependencies (services, modules, or components) into other components, making it easier to manage and test these dependencies.
   
4. What are directives in AngularJS?
   
   Directives are DOM element identifiers that instruct AngularJS’s HTML compiler to add specified behavior or functionality to those elements. They can be used to create reusable components, handle events, manipulate the DOM, and much more.
   
5. How does AngularJS handle routing?
   
   AngularJS provides a built-in routing mechanism called ngRoute or the newer AngularUI Router. These modules allow you to define routes and associate them with specific templates and controllers, enabling navigation within a single-page application.
   
6. What is the difference between ng-if and ng-show/ng-hide directives?
   
   The ng-if directive completely removes or recreates an element based on a condition, while ng-show/ng-hide toggles the visibility of an element by adding or removing the CSS display property.
   
7. Explain the concept of controllers in AngularJS?
   
   Controllers in AngularJS are responsible for handling the logic and behavior of a specific part of the application. They help to separate concerns and manage the interaction between the view and the model.
   
8. What is the $scope object’s purpose in AngularJS?
   
   The $scope object serves as a bridge between the controller and the view. It contains the model data and functions that are accessible in the view, allowing for data binding and manipulation.
   
9. How does AngularJS support form validation?
   
   AngularJS provides form validation through various directives such as ng-required, ng-pattern, ng-minlength, and ng-maxlength. It also offers CSS classes and properties to indicate the validation state of form elements.
   
10. Explain the concept of services in AngularJS.
    
    Services are singleton objects in AngularJS that provide reusable functionalities across different parts of the application. They can be used to encapsulate business logic, handle API calls, share data between components, and more.
    
11. What is the purpose of filters in AngularJS?
    
    Filters allow you to format and transform data in AngularJS templates. They can be used for tasks such as currency formatting, date formatting, sorting, filtering, and more.
    
12. How can you make an AJAX call in AngularJS?
    
    AngularJS provides the $http service, which allows you to make HTTP requests to fetch data from APIs or send data to a server. It supports various HTTP methods like GET, POST, PUT, DELETE, and more.
13. What are factories and providers in AngularJS?
    
    Factories and providers are two ways of creating services in AngularJS. Factories are simpler and provide an easy way to create services, while providers offer more flexibility and configuration options.
    
14. Explain the concept of the digest cycle in AngularJS.
    
    The digest cycle is a mechanism in AngularJS that tracks changes to the $scope objects and updates the view accordingly. It ensures that any changes in the model are reflected in the view and vice versa.
    
15. What is the purpose of the $watch function in AngularJS?
    
    The purpose of the $watch function in AngularJS is to observe changes in the value of a specific expression or variable and trigger a callback function when the value changes. It allows developers to track changes in the model and perform actions accordingly. The $watch function takes two arguments: the expression or function to watch, and the callback function to execute when the value changes. This enables reactive behavior, such as updating the view when the model changes or performing additional logic based on the updated value.
    
16. Explain the concept of promises in Angular JS?
    
    Promises in AngularJS are a design pattern used for handling asynchronous operations. They represent the eventual completion or failure of an asynchronous task and allow developers to chain actions together, making it easier to manage asynchronous code flow and handle results asynchronously.
    
17. How can you make an HTTP request in Angular JS? 
    
    In AngularJS, you can make an HTTP request using the $http service. It provides methods like $http.get(), $http.post(), etc., to send HTTP requests to a server and receive responses. These methods allow you to specify the URL, request parameters, and headers, and handle the response asynchronously.
    
18. Do you perform unit testing in AngularJS?
    
    In AngularJS, unit testing can be performed using frameworks such as Jasmine and Karma. Here are the steps to perform unit testing in AngularJS:
    
    • Set up the testing environment by installing the required dependencies (Jasmine, Karma) and configuring Karma for your project.
    • Write test cases using Jasmine’s testing syntax. These test cases typically involve creating instances of controllers, services, or directives and asserting expected outcomes.
    • Use dependency injection to inject mock or stub objects into the units being tested. This helps isolate the unit being tested and ensures reliable and independent test results.
    • Set up the test runner (Karma) to execute the test cases. Karma launches a browser and runs the tests in an isolated environment, providing feedback on test results.
    • Examine the test results for any failures or mistakes. Adjust the code or test cases as needed to fix issues.
    • Continuously run tests during development to catch regressions and ensure code changes do not introduce unintended issues.
      
19. How can you communicate between components in AngularJS?
    
    In AngularJS, there are multiple ways to communicate between components:
    
    • Using Parent-Child Component Communication: Data can be passed from a parent component to a child component using component bindings. The parent component can pass data to the child component via attributes, and the child component can access it using $scope or @ bindings.
    • Using Services: Shared services can be created to facilitate communication between components. Components can inject and use the same service to share data or trigger events. The service acts as a mediator between components.
    • Using Event Emitters: Events can be emitted from one component and listened to by another using $emit, $broadcast, and $on. This allows components to communicate indirectly by triggering and listening to custom events.
    • Using $rootScope: AngularJS provides a $rootScope that acts as a global scope. Components can use $rootScope to broadcast and listen to events, allowing communication across the entire application.
    • Using Observables: AngularJS supports reactive programming through libraries like RxJS. Components can use observables to publish and subscribe to data streams, enabling efficient and real-time communication.
      
20. What are the best practices to follow when developing with AngularJS?
    
    When developing with AngularJS, following these best practices can enhance the quality and maintainability of your code:
    
    • Adhere to the modular structure and component-based architecture.
    • Use proper dependency injection to promote reusability and testability.
    • Follow the single responsibility principle and keep controllers and services focused.
    • Utilize directives for reusable UI components.
    • Optimize performance by minimizing DOM manipulation and using one-time bindings when appropriate.
    • Implement proper error handling and utilize AngularJS’s exception-handling mechanisms.
    • Write unit tests using frameworks like Jasmine or Karma to ensure code quality and reliability.
    • Take advantage of AngularJS’s built-in directives and services instead of reinventing functionality.
    • Apply consistent coding conventions and style guidelines for readability and maintainability.
    • Regularly update to the latest version of AngularJS and keep dependencies up to date for security and performance improvements.

The provided AngularJS interview question list serves as a comprehensive resource for assessing candidates’ knowledge and skills in AngularJS development. It covers various essential topics and can help interviewers evaluate an individual’s proficiency and suitability for AngularJS-related roles effectively. To enhance your skills and knowledge, consider enrolling in the Sensation Solutions Training program. With their comprehensive curriculum and expert guidance, you’ll gain the expertise needed to excel in Angular JS development and confidently tackle the interview.