Latest Top interview questions and answers for a Angular JS developer for experienced and freshers, get ready to crack any interview.

Basics of AngularJS interview question:

1. What is AngularJS?
   • Answer: AngularJS is a JavaScript-based open-source front-end web application framework developed and maintained by Google. It is designed to make both the development and testing of such applications easier.
2. Explain two-way data binding in AngularJS.
   • Answer: Two-way data binding in AngularJS is a synchronization mechanism that binds the model and the view. Any changes in the model instantly reflect in the view, and vice versa.
3. What is the AngularJS digest cycle?
   • Answer: The digest cycle is the process in which AngularJS updates all the bindings between the model and the view. It loops through all the watchers and updates the view if a change is detected.
4. Describe dependency injection in AngularJS.
   • Answer: Dependency Injection (DI) is a design pattern in which components receive their dependencies from an external source. AngularJS has a built-in DI system that helps manage components and their dependencies.
5. What is the role of directives in AngularJS?
   • Answer: Directives are markers on DOM elements that tell AngularJS to attach a specified behavior to that DOM element or transform the DOM element and its children.
6. Explain the concept of scopes in AngularJS.
   • Answer: Scopes in AngularJS are objects that refer to the application model. They serve as a context for expressions and act as glue between the controller and the view.
7. What is the purpose of filters in AngularJS?
   • Answer: Filters in AngularJS format the value of an expression for display to the user. They can be used to format data, convert to uppercase/lowercase, filter arrays, and more.
8. What are AngularJS services?
   • Answer: Services in AngularJS are singletons that carry out specific tasks common to web applications, such as logging, data sharing, communication with servers, etc.
9. Explain the concept of $scope in AngularJS.
   • Answer: $scope is an object that refers to the application model. It is an execution context for expressions. Scopes can nest, and child controllers can access parent scopes.
10. How does AngularJS handle forms and form validation?
    • Answer: AngularJS provides a powerful form handling mechanism, including two-way data binding for form inputs and built-in validation directives like ng-required and ng-pattern.

Advanced AngularJS Concepts interview question:

11. What is the AngularJS routing and how is it configured?
    • Answer: AngularJS routing allows the developer to create single-page applications with navigation without the need for page reloading. It’s configured using the $routeProvider service.
12. Explain the concept of dependency injection in AngularJS.
    • Answer: Dependency injection in AngularJS is a way to make components more modular and easier to test. It allows components to declare their dependencies, and AngularJS injects them at runtime.
13. What is the purpose of the $http service in AngularJS?
    • Answer: The $http service in AngularJS is used for making AJAX requests to a server. It facilitates communication between the application and a server or external resources.
14. How does AngularJS support custom directives?
    • Answer: AngularJS supports custom directives using the directive function. Custom directives can be created to encapsulate complex behaviors and reusable components.
15. What is the purpose of the $rootScope in AngularJS?
    • Answer: The $rootScope is the parent scope created for the AngularJS application. It is available for the entire application and can be used to store global data.
16. Explain the concept of transclusion in AngularJS.
    • Answer: Transclusion is the process of including the contents of one element into another element. In AngularJS, it is often used in custom directives to include content from the directive’s consumer.
17. What are AngularJS decorators, and how are they used?
    • Answer: Decorators in AngularJS are functions that allow the modification of services, controllers, or providers. They can be used to extend or override the functionality of existing components.
18. What is the role of the $compile service in AngularJS?
    • Answer: The $compile service in AngularJS is responsible for compiling a piece of HTML and linking it with a scope. It is often used internally by directives.
19. How does AngularJS handle animations?
    • Answer: AngularJS provides the ngAnimate module to handle animations. It allows the developer to animate the entrance, leave, and move of elements in the DOM.
20. Explain the concept of AngularJS digest cycle and watchers.
    • Answer: The digest cycle is a loop that iterates over all the watchers in AngularJS and checks for changes in the model. Watchers are expressions that AngularJS monitors for changes.

Testing in AngularJS interview question:

21. How does testing work in AngularJS?
    • Answer: AngularJS provides a testing framework based on Jasmine. It includes tools like ngMock for mocking dependencies and ngMockE2E for end-to-end testing.
22. What is end-to-end testing in AngularJS, and how is it done?
    • Answer: End-to-end testing in AngularJS involves testing the entire application to ensure all components work together as expected. Tools like Protractor are commonly used for AngularJS end-to-end testing.
23. What is the purpose of Karma in AngularJS testing?
    • Answer: Karma is a test runner for JavaScript that is configured for AngularJS. It launches browsers, runs tests, and provides feedback on the test results.
24. Explain the concept of dependency injection in AngularJS testing.
    • Answer: In AngularJS testing, dependency injection is used to inject mock services or dependencies into controllers, services, or other components for isolated testing.
25. How can you test asynchronous code in AngularJS?
    • Answer: AngularJS provides the $timeout service, which can be used to handle asynchronous code in tests. Jasmine also provides done function for testing asynchronous code.

Angular 2+ interview question:

26. What are the key differences between AngularJS and Angular?
    • Answer: Angular (Angular 2 and later) is a complete rewrite of AngularJS (Angular 1.x). It introduces a component-based architecture, improved performance, and a more modern approach to web development.
27. Explain the concept of modules in Angular.
    • Answer: In Angular, modules are containers for a set of related components, directives, services, and pipes. They help organize and encapsulate code and functionality.
28. What are Angular services, and how are they different from AngularJS services?
    • Answer: In Angular, services are singleton objects used to organize and share code across the application. They are similar to AngularJS services but follow a more modern and modular design.
29. What is the Angular CLI, and how is it used?
    • Answer: The Angular CLI (Command Line Interface) is a powerful tool for initializing, developing, scaffolding, and maintaining Angular applications. It simplifies the development workflow and provides a consistent structure.
30. How does Angular handle forms and form validation in comparison to AngularJS?
    • Answer: Angular introduces the FormsModule and ReactiveFormsModule for handling forms. It provides a more reactive and flexible approach to form handling and validation.