45+Top Angular JS Interview Questions & Answers [SOLVED]

Last updated on 30th May 2020, Blog, Interview Questions

JavaScript framework called AngularJS. With the use of the script> element, it may be included in an HTML page. It extends HTML attributes with Directives and binds data to HTML with Expressions. It is a JavaScript framework written in JavaScript. In single-page application (SPA) projects, it is used. It adds new characteristics to HTML DOM and improves user interaction by increasing responsiveness.

1. How does AngularJS work?

Ans:

Model-view-controller (MVC) architecture is the foundation of the robust JavaScript framework known as AngularJS. AngularJS functions fundamentally by adding new properties and directives to HTML that offer dynamic functionality. When an AngularJS-powered web page is launched, the framework examines the HTML to find these unique characteristics and directives before creating and managing the relevant JavaScript objects and bindings.

2. How does AngularJS work?

Ans:

Two-way data binding: AngularJS makes it possible for the data model and the view to automatically sync, doing away with the need for manual updates and streamlining development.

Directives: AngularJS directives let programmers add new HTML elements and properties, making it possible to build reusable components and improving code readability.

Dependency injection: The built-in dependency injection mechanism in AngularJS helps to handle dependencies across various components, encouraging modularity and testability.

Model-View-Controller (MVC) architecture: AngularJS uses the MVC pattern to organize and maintain its code by separating the application’s logic from its data and display concerns.

3. Explain two-way data binding in AngularJS.

Ans:

Model to View (Data to UI): Any changes made to the data model are automatically reflected in the UI. When a value in the model is updated, AngularJS detects the change and updates the corresponding UI element bound to that value. This ensures that the UI is always up-to-date with the underlying data.

View to Model (UI to Data): Similarly, when a user interacts with the UI element bound to a particular value, AngularJS captures that interaction and updates the corresponding data in the model. For example, if a user enters text in an input field, AngularJS captures that input and updates the associated data variable.

4. What are the advantages of using AngularJS?

Ans:

The development process may be streamlined thanks to AngularJS since it provides a solid foundation upon which to construct interactive web apps. AngularJS’s two-way data binding and other capabilities streamline the development process by eliminating the need for manual updates and keeping the data model and user interface in sync with one another. The robust directive system in AngularJS encourages code reuse by letting programmers create their own HTML elements and attributes and encapsulate complicated functionality into reusable components.

5. What are directives in AngularJS?

Ans:

AngularJS’s core feature, directives, enable programmers to add new behaviors and functionalities to HTML. They are tags placed on DOM elements that AngularJS utilizes to modify and direct the output. With directives, programmers may make reusable parts, increase code modularity, and define UI behavior in a declarative fashion. There are a number of predefined directives in AngularJS, such as ng-app, ng-model, and ng-repeat, that facilitate frequent tasks including application startup, data binding, and collection iteration.

6. What is dependency injection in AngularJS?

Ans:

Dependency injection (DI) in AngularJS is a design pattern and a core feature that enables the efficient management and injection of dependencies into components. In AngularJS, DI helps to decouple components and promotes modularity, reusability, and testability.

7. How does AngularJS implement MVC architecture?

Ans:

Model: The model in AngularJS is a representation of the application’s data and business logic. It is often referred to as arrays or JavaScript objects. The model stores and manipulates the application’s data and may be connected to the view to display changes in real time.

View: The view is the part of the UI that the user actually sees and uses. HTML templates with extra directives for dynamic functionality are used to define the view in AngularJS. The view’s job is to show off what the model has to offer and take in everything the user has to say about it.

Controller: AngularJS’s controllers serve as go-betweens for the model and the view. The logic of the application is stored in these, and they manage how the model and the view communicate with one another. In response to user actions, controllers modify the model and then update the view to reflect the new state of the model.

8. What is the difference between ng-bind and ng-model directives?

Ans:

ng-bind: An AngularJS model expression can be bound to the content of an HTML element using the ng-bind directive. It evaluates the specified expression and replaces the inner HTML or value of the HTML element with the result. The binding is one-way, meaning changes in the model will update the view, but changes in the view will not affect the model. ng-bind is commonly used for displaying dynamic data or computed values on the page.

ng-model: The ng-model directive, on the other hand, facilitates two-way data binding between the model and the view. It binds the value of an HTML element, such as an input field or select box, to a property in the AngularJS model. Any changes made by the user in the view will automatically update the corresponding model property, and vice versa. ng-model is frequently used in forms to capture user input and synchronize it with the underlying data model.

9. Explain the concept of scope in AngularJS.

Ans:

The execution context that connects the model and the view is referred to as the scope in AngularJS. It serves as a link between the controller (or component) and the view, allowing for synchronization and communication.

In AngularJS, the scope is an object that acts as the data model. It stores the data attributes and operations available inside a certain area of the application, often linked to a controller. Data binding has a context thanks to the scope, which enables values to be exchanged and modified between the model and the view.

10. What is a digest cycle in AngularJS?

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A digest cycle is AngularJS’s method of detecting and reacting to changes in the model data and revising the relevant bindings in the view.

11. How do you define a controller in AngularJS?

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The logic and functionality may be specified, variables can be initialized, and methods to interact with the view and modify data can be defined all inside the controller function. The specified controller serves as a connection point between the view and the underlying data, enabling communication and synchronization between them.

12. What is the role of services in AngularJS?

Ans:

Services play a crucial role in AngularJS because they provide a method to encapsulate and share functionality across various sections of an application. Singleton objects are only instantiated once and can be injected into various components, such as controllers, directives, and other services.

13. What are filters in AngularJS?

Ans:

Filters are a component of AngularJS that let you format, alter, and filter data in the display layer of your application. Expressions in HTML templates are subjected to filters to change how data is shown to the user.

14. What are the different types of directives in AngularJS?

Ans:

Attribute Directives: Attribute directives are the most common type of directive in AngularJS. They modify the behavior or appearance of an existing HTML element by applying custom behavior or functionality through the use of attributes.

Element Directives: Element directives create reusable components by extending HTML with new custom elements. They allow you to define your own HTML elements and encapsulate their behavior and appearance within a directive.

Comment Directives: Comment directives are directives that are applied to HTML comments. They are used less frequently compared to attribute and element directives.

15. Explain the concept of a module in AngularJS.

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A module in AngularJS organizes related code, such controllers, services, directives, filters, and more, into a more manageable unit. It helps developers manage dependencies and customize the application by organizing and modularizing the source.

16. What do AngularJS directives do?

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AngularJS employs directives, which are markers on DOM elements, to associate behavior with those components. For the purpose of encapsulating certain behaviors or functions, they can be used to construct unique components, attributes, or classes.

17. What differentiates ng-if from ng-show directives?

Ans:

Evaluation: The ng-if directive analyzes an expression and entirely destroys or recreates the element from the DOM depending on truthiness. DOM elements and their contents are eliminated if the expression is false. Re-rendering and DOM insertion occur if the expression is true. Changing the ng-if condition destroys and recreates the element’s scope.

CSS Display: The ng-show directive shows or hides elements using CSS. ng-show displays the element by setting its CSS display property to its default value if the expression is true. The element’s show property is hidden if the expression is false. Hidden elements and scopes stay in the DOM.

Performance: ng-if removes and recreates the element from the DOM, which might influence performance more than ng-show, particularly if the condition changes often. ng-show merely toggles the CSS display property, making it faster.

18. Explain the concept of routing in AngularJS.

Ans:

Routing helps you to develop single-page applications (SPAs) with many views and navigation in AngularJS. It loads material and components depending on the URL without reloading the page.

AngularJS’s ngRoute module lets you configure your application’s routes. The $routeProvider service and the ngRoute module must be included in your application. A URL path, template or template URL, and controller constitute a route.

19. How do you handle AJAX requests in AngularJS?

Ans:

AngularJS’s $http service handles AJAX queries. $http makes HTTP requests and replies easy.

AngularJS AJAX requests:

Inject the $http service: Inject the $http service into your controller or service to perform the AJAX request. The controller or service function may rely on $http.

Request AJAX: To send an HTTP request to the server, use the $http service’s get(), post(), put(), delete(), etc. These methods return promise objects for handling responses.

Address it: The $http methods’ promise lets you attach success and error callbacks using.then(). If the request succeeds, the success callback is run; otherwise, the error callback is invoked.

Access response data: Use response.data to retrieve response data, such as the JSON payload, in the success callback. Process and utilize the data as required.

Error handling: Handle AJAX request failures in the error callback. The response object lets you obtain error data and show an error message.

20. What are the different types of scopes in AngularJS?

Ans:

There are three different scope types in AngularJS:

• $rootScope
• Controller Scopes
• Directive Scopes

21. Explain the role of ng-repeat directive.

Ans:

AngularJS’s ng-repeat directive may loop over an array or collection and create HTML components dynamically depending on each item in the collection. It offers an easy method to show and change data in the view by allowing you to repeatedly paste a block of HTML code for each item in the collection.

22. What is ng-app directive in AngularJS?

Ans:

The AngularJS framework is initialized and bootstrapped for a given region of an HTML page.Applying the ng-app directive to an element initiates compilation of the content and makes use of AngularJS functionalities there. The ng-app directive denotes the entry point for AngularJS to take over the application’s lifecycle management for the given section.

23. How do you handle exceptions in AngularJS?

Ans:

AngularJS has numerous tools and recommended practices for handling exceptions and errors. AngularJS error handling:

Global Exception Handler: The $exceptionHandler service lets you create a global exception handler. A custom exception handler may capture and manage uncaught exceptions in your AngularJS application.

Error Interceptor: AngularJS’s $http service interceptors let you manage HTTP request errors. Before they reach the application, interceptors may capture and handle network and server-side problems.

Error Routing: AngularJS’ $routeProvider handles error routing. A custom route may handle page not found (404) and server failures. You may improve error handling by customizing the route to show a custom error page or execute custom error handling.

Error Logging: Logging failures helps debug and troubleshoot. AngularJS integrates with $log or additional logging libraries to collect and record problems. Logging errors helps you find and fix application problems.

Error Display: You may notify users of errors by displaying error messages. Based on the application’s error status, AngularJS directives like ngMessages or custom error-handling directives may display error messages in the user interface.

24. What is the difference between one-way and two-way data binding?

Ans:

One-Way Data Binding: Data goes from model to view in one-way data binding. The model updates the view, but the view does not influence the model. The view automatically reflects model updates, however user changes in the view do not propagate back to the model. One-way data binding is efficient for data presentation and model synchronization.

Two-Way Data Binding: Two-way data binding lets data flow between the model and display. Both model and view changes update each other. This bidirectional flow synchronizes the model and view in real time. Two-way data binding automates model and view updates and event handling, simplifying development.

25. Explain the concept of transclusion in AngularJS.

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You may use AngularJS’s transclusion features to include any text in the body of a directive. To avoid breaking the original data, you may design reusable components that encapsulate and transform supplemental data.

26. How do you perform unit testing in AngularJS?

Ans:

Set up the Testing Environment: Install Karma and Jasmine globally on your development machine using a package manager like npm.

Write Test Suites and Specs: Create test suites (describe blocks) and individual test specs (it blocks) using Jasmine’s syntax.

Inject Dependencies: Use AngularJS’s dependency injection to inject the necessary dependencies (services, controllers, etc.) into your tests.

Test AngularJS Components: Write tests to cover various AngularJS components, such as controllers, services, directives, filters, etc. Use mock dependencies or $httpBackend to simulate external dependencies or API calls.

Run Tests: Run the tests using the Karma test runner by executing the karma start command. Karma will launch the specified browsers and execute the test files defined in the configuration.

Analyze Test Results: Karma will provide test results and feedback in the terminal or command prompt. You can see which tests passed, failed, or encountered errors. Detailed error messages and stack traces are displayed to aid in debugging.

27. What does AngularJS assure mean?

Ans:

Two-Way Data Binding: AngularJS automatically synchronizes model and display data. This minimizes manual data processing and simplifies development.

Modular Architecture: AngularJS encourages modularity to structure code into reusable and manageable components. Modularity improves code structure, reuse, and testability.

Dependency Injection: A dependency injection framework for testing, reusing code, and loose coupling is already included in AngularJS.

Community and Support: AngularJS has a big and active developer community that provides resources, documentation, tutorials, and support. AngularJS learning and debugging may benefit from community help.

28. Explain the concept of directives’ compile and link functions.

Ans:

The compile function is called once during the compilation step of the directive. Template modification and DOM transformation are its primary responsibilities. Upon receiving the directive’s template, the compile function either returns a linking function or an object comprising pre-link and post-link functions.

The directive’s link function is in charge of connecting the directive’s template to its appropriate scope. At the time of each directive’s execution, it receives the scope, element, and attributes as arguments.

29. How do you share data between controllers in AngularJS?

Ans:

AngularJS has multiple methods for controller data sharing. Common ways are:

Services: Singleton objects in AngularJS may be injected into numerous controllers. You can inject a service that stores and manipulates shared data into controllers that require it. The service helps controllers exchange and update data.

Using $rootScope: The parent scope of all AngularJS scopes is $rootScope. Inject $rootScope to access shared data from any controller. Sharing data with $rootScope might cause code complexity and conflicts.

Events: AngularJS enables components to communicate through events. $emit, $broadcast, and $on transmit and receive events. Controllers may broadcast data changes as events, and other controllers can update their data appropriately.

Using Parent-Child connection: If you have a parent-child connection between controllers (e.g., nested views or directives), bindings may transmit data from the parent to the child. The child controller may access and alter shared data via the inherited scope from the parent controller.

30. What are the best practices for organizing code in AngularJS?

Ans:

Maintainable and scalable AngularJS apps need code organization. AngularJS code organization tips:

Module-Based Structure: Separate code by functionality or feature. Modules should include linked controllers, services, directives, and other components. Modularity improves code reuse, testability, and maintainability.

Folder Structure: Group files into logical folders. Create directories for modules, controllers, services, directives, filters, and views. This setup simplifies file management as your program expands.

Minification and Bundling: Reduce file size and load time by minifying and bundling JavaScript scripts for production. Gulp, Grunt, and Webpack automate this.

Documentation: Explain your code to other developers. Include comments, inline documentation, and README files describing your components and modules’ purpose, use, and concerns.

31. Explain the concept of the $scope.$apply() function.

Ans:

The $scope.$apply() method in AngularJS is used to manually initiate the digest cycle and refresh the model-view bindings. A change has happened outside of the AngularJS context, and AngularJS has to run a digest cycle to reflect this in the user interface.

32. How do you handle form submission in AngularJS?

Ans:

AngularJS’s form validation and ngSubmit directive manage form submission. AngularJS form submission:

Form Validation: Use ng-required, ng-pattern, ng-minlength, etc. to validate form inputs. These directives will automatically verify the form and determine its validity state in AngularJS.

ngSubmit Directive: Bind the form element’s ngSubmit directive to a controller function. Form submission calls this method.

Form Submission Logic: In the controller function, you may validate data, transmit data to the server, or go to another page. You may additionally check the form’s legitimacy and show messages or take actions accordingly.

33. What is ng-class directive used for?

Ans:

AngularJS’s ng-class directive is used to dynamically assign CSS classes to HTML elements according to predetermined criteria or phrases. As the application’s state changes, you can easily modify the way items look and behave. The ng-class directive may be used on any HTML element, and its value can be either an expression or an object.

34. How do you perform dependency injection in AngularJS?

Ans:

Dependency injection is a fundamental concept in AngularJS that lets you avoid having to manually create and manage dependencies by declaring them and then injecting them into your components (controllers, services, etc.). Using this method increases the code’s modularity, reusability, and testability.

35. Explain the concept of template caching in AngularJS.

Ans:

$templateCache Service: AngularJS’s $templateCache key-value store stores HTML templates. The $templateCache.put() function allows manually add templates to the cache using a key and HTML content.

Template Loading: AngularJS examines the $templateCache for templates required by directives and components. The cached template is retrieved if found. If not, AngularJS will request the template through HTTP.

Manual Template Caching: You may preload templates with AJAX queries or manually fill the $templateCache during construction. This method is handy when templates are used in many regions of the application or to save server round-trips for widely used templates.

36. What is ng-options directive used for?

Ans:

AngularJS uses the ng-options directive to create option> components for choose> dropdown lists on the fly. It offers an adaptable and potent method for filling and binding data to dropdown lists in AngularJS applications.

37. How do you handle internationalization (i18n) in AngularJS?

Ans:

Localization: Include the angular-translate module or another i18n library to configure AngularJS for i18n. This module offers localization and language-specific translation files.

Translate: Create language-specific translation files for each supported language. Key-value pairs indicate the original and translated information in these files. Translate needed text and messages into chosen languages.

Configure AngularJS Module: Set the default language and translation file directory. I18n functionality requires module setup and dependencies.

Change Language: Provide a menu or button to switch languages. Reload the translated content once the user chooses a language in the AngularJS module.

Compile-Time or Run-Time Translation: Depending on the i18n library and technique, translation may be done compile-time or run-time. Compile-time translation bundles pre-compiled translation files with the program. Run-time translation loads translation files dynamically.

38. Explain the concept of AngularJS digest cycle optimization.

Ans:

Digest cycle optimization refers to techniques and best practices aimed at improving the performance and efficiency of the digest cycle. By minimizing the number of unnecessary digest cycles and reducing the amount of work performed during each cycle, you can optimize the overall performance of your AngularJS application.

39. What is the difference between $watch and $observe in AngularJS?

Ans:

$watch: The $watch method of the AngularJS $scope object is used to monitor the values of variables and expressions inside the scope. Data changes within a specified scope may be tracked using this feature. A callback function is run whenever the value being monitored changes, based on an expression or function you provide.

$observe: Within AngularJS directives, the $observe function may be accessed through the $attrs object. Its goal is to monitor a directive’s or element’s characteristics for any changes. You may keep an eye on the values of attributes by supplying the name of the attribute and a callback function.

40. How do you handle browser back and forward buttons in AngularJS?

Ans:

In AngularJS, you may manage browser back and forward buttons by employing the $location service and the $rootScope object. In AngularJS, you can properly manage browser back and forward buttons by using the $location service and event handling. This method allows you to react to history updates and synchronize the state of your application with the browser’s navigation activities.

41. What are the different types of event handling in AngularJS?

Ans:

In AngularJS, there are multiple ways to handle events. Here are the different types of event handling approaches commonly used in AngularJS:

ng-click Directive: The ng-click directive handles HTML element click events. It lets you set a click function.

ng-submit Directive: The ng-submit directive handles form submissions. You may define a form-submitted function.

ng-change Directive: The ng-change directive handles changes in text inputs, checkboxes, and select items.

ng-keypress, ng-keydown, ng-keyup Directives: ng-keypress, down, up Directives manage keyboard events. ng-keypress, ng-keydown, and ng-keyup activate when a key is pushed and released. These directives let you define an event-triggered function.

ng-focus, ng-blur Directives: ng-focus, blur Directives manage focus-related events. When an element loses focus, it triggers ng-blur. They let you provide an event-triggered function.

42. How do you implement custom filters in AngularJS?

Ans:

Here’s an overview of how to implement custom filters in AngularJS:

• Create a Filter Function
• Register the Filter
• Use the Custom Filter
• Dependency Injection

43. Explain the role of ng-view directive.

Ans:

The ng-view directive in AngularJS is used to define a placeholder or container within which the content of various views can be dynamically imported and displayed based on the current route or URL. This directive is fundamental for implementing client-side routing in AngularJS applications.

44. How do you perform data binding in AngularJS?

Ans:

Here’s an overview of how data binding is performed in AngularJS:

• Interpolation ({{ }})
• One-Way Binding (ng-bind)
• Two-Way Binding (ng-model)
• Event Binding (ng-click, ng-change, etc.)

45. What is the role of the $http service in AngularJS?

Ans:

When making HTTP requests to get or transmit data to a server, AngularJS’s $http service is crucial. It provides a simple, useful technique for interacting with RESTful APIs, communicating with distant servers, and carrying out CRUD (Create, Read, Update, Delete) activities.

46. Explain the concept of promises chaining in AngularJS.

Ans:

Promises chaining is a technique in AngularJS that lets you conduct numerous asynchronous activities in sequence by linking together different promises. It offers a clear and organized method for managing asynchronous jobs and the relationships between them.

47. How do you handle form validation asynchronously in AngularJS?

Ans:

AngularJS’s $asyncValidators property of the form controls allows for asynchronous form validation processing. You may now use asynchronous actions like performing HTTP queries or waiting for a server response in your own validation logic.

48. What is the role of the ng-init directive in AngularJS?

Ans:

When a template is loaded in AngularJS, values may be initialized or expressions can be run using the ng-init directive. When a scope is defined for a given element, you may use it to specify initial values or carry out predetermined actions.

49. Explain the concept of AngularJS animations.

Ans:

The following elements define AngularJS animations:

CSS Transitions and Animations: AngularJS animates page components using CSS transitions and animations. CSS classes may describe animation effects using duration, timing function, delay, and keyframes.

ngAnimate Module: AngularJS’s ngAnimate module handles animations. It offers directives and classes to easily add animations to your program.

Animation Triggers: Events and state changes trigger AngularJS animations. You may animate items entering or leaving the DOM, adding or removing classes, or changing scope values.

Animation Configuration: AngularJS’s $animateProvider lets you adjust duration, ease, and delay. This lets you adjust application animations.

50. What is the purpose of the $compile service in AngularJS?

Ans:

Compiling an HTML template and associating it with a scope is the job of AngularJS’s $compile service. An HTML string or element is parsed, and the result is an AngularJS view ready for use.

51. How do you handle route change events in AngularJS?

Ans:

The $rootScope object in AngularJS provides access to route change events such as $routeChangeStart, $routeChangeSuccess, $routeChangeError, and $routeUpdate. Whenever the application’s path changes, you may trigger your own custom code using these events.

52. What is the role of the $rootScope in AngularJS?

Ans:

Here are the key roles of the $rootScope in AngularJS:

• Global Scope
• Event Broadcasting
• Sharing Data
• Lifecycle Events
• AngularJS Core Functionality

53. How do you implement a custom directive in AngularJS? .

Ans:

Here’s an overview of the steps involved in implementing a custom directive:

• Define the Directive
• Specify the Directive Restrictions
• Implement the Directive’s Link Function
• Register the Directive with AngularJS Module
• Use the Directive

54. What is the difference between ng-repeat and ng-options directives?

Ans:

When displaying and iterating over collections of data, AngularJS’s ng-repeat and ng-options directives serve distinct purposes:

ng-repeat:To cycle over an array or object collection and create HTML elements for each item in the collection, use the ng-repeat directive.It is typical to repeat a block of HTML code for each item in the collection using an HTML element or a custom directive.

ng-options:The ng-options directive was created expressly to provide the choices for an HTML select> element.It takes expressions that result in an array or object collection, and then produces the option> elements using the collection.

55. Explain the concept of lazy loading in AngularJS

Ans:

Lazy loading is a method for loading modules, components, or resources dynamically when they are actually needed, rather than loading everything upfront. It helps improve the initial loading time and overall performance of an application by only loading the necessary parts when required.

56. How do you implement sorting and filtering in AngularJS?

Ans:

Learn the fundamentals of doing filtering and sorting with AngularJS by reading this overview:

Sorting: Utilize the orderBy filter to sort an array by a given attribute or expression. Using the ng-repeat directive in your HTML template, you may loop over the array, and then connect (through |) the orderBy filter to the property or expression you want to use to determine the order.

Filtering: The filter filter may be used to narrow down the items in an array to those that meet certain criteria. Specify the filtering criteria as an object or a string, and then use the ng-repeat directive and filter filter in your HTML template.

57. What are the different types of interpolation in AngularJS?

Ans:

In AngularJS, there are three types of interpolation:

• Double Curly Brace {{ }}
• ng-bind Directive
• ng-bind-template Directive

58. How do you handle cookies in AngularJS?

Ans:

The ng Cookies module of AngularJS provides access to the $cookies service, which may be used to manipulate cookies. Cookies may be read and written with ease in your AngularJS app with the help of this module.

59. Explain the concept of decorators in AngularJS.

Ans:

Providers, directives, filters, and other AngularJS components may be enhanced with the help of decorators. Using decorators, you may modify the functioning of good components without modifying their source code. This idea is also referred to as a decorative component.

60. What is the role of the $location service in AngularJS?

Ans:

The $location service’s function is described here:

URL Reading: The $location service lets you read the URL’s protocol, host, port, path, query arguments, and hash. It gives you attributes and methods to evaluate and utilize the current URL in your application.

URL Modification: The $location service lets you change the current URL. Path, query parameters, and hash may update the URL. The $location service’s attributes and methods make dynamic URL updates straightforward.

URL Parsing: The $location service parses URLs to extract information. It uses absUrl(), protocol(), host(), port(), and others to parse and obtain URL components. When you require custom logic or data extraction depending on URL structure, this processing is beneficial.

61. How do you implement pagination in AngularJS?

Ans:

This is an overview of the AngularJS pagination system and how to set it up:

• Define Pagination Variables
• Slice the Data
• Update Pagination Variables
• Update Data Source
• Display Pagination Controls

62. Explain the concept of directive priority in AngularJS.

Ans:

Directive priority is a concept that determines the order in which directives are executed and applied to DOM elements. Directive priority is relevant when multiple directives are declared on the same element, and their execution order may affect the final result.

63. What is the role of the ng-disabled directive in AngularJS?

Ans:

The ng-disabled directive in AngularJS is used to disable or enable an HTML element based on an expression’s evaluation result. It allows you to conditionally disable or enable form controls, buttons, or any other interactive elements in your application.

64. How do you handle cross-site scripting (XSS) in AngularJS?

Ans:

In AngularJS, handling cross-site scripting (XSS) is a priority to ensure the security of web applications. AngularJS provides several built-in mechanisms to tackle XSS vulnerabilities effectively. One of the key features is contextual autoescaping, where AngularJS automatically escapes potentially malicious content when it is outputted into the HTML document. This default behavior protects against most XSS attacks by default.

65. Explain the concept of the $route service in AngularJS.

Ans:

The $route service is an integral part of AngularJS that allows for the creation of single-page applications (SPAs) by providing routing functionality. It facilitates application navigation by letting you construct routes and associate them with various view/template combinations. In order to set up routes, the $route service collaborates with the $routeProvider module.

66. What is the difference between $scope and $rootScope in AngularJS?

Ans:

In AngularJS, the $scope and $rootScope objects serve distinct purposes within the application’s architecture. The $scope object represents the data model of a specific view or controller, providing a localized scope for data and functions. Each controller has its own $scope instance, facilitating data binding and communication within that controller’s context. On the other hand, the $rootScope object acts as the top-level scope accessible throughout the application. It serves as a global event bus, enabling communication and data sharing between different components that are not directly related. While $scope is used for local communication and encapsulation, $rootScope allows for broader communication and should be used judiciously to maintain a clear separation of concerns.

67. How do you handle file uploads in AngularJS?

Ans:

Handling file uploads in AngularJS involves a combination of HTML, JavaScript, and AngularJS directives. Here’s an overview of the process:

HTML File Input: Create an HTML form with a file input element to allow users to select files for upload.

AngularJS Directives: Utilize AngularJS directives like ng-model and ng-change to bind the file input to a model variable and capture changes when a file is selected.

68. What is the role of the ng-cloak directive in AngularJS?

Ans:

The ng-cloak directive in AngularJS is used to prevent the display of uncompiled AngularJS markup in HTML templates during the page load. Its role is to ensure that the AngularJS expressions and directives are processed and evaluated before they become visible to the user.

When AngularJS applications are initially loaded, the HTML templates may briefly display the raw AngularJS code or placeholders until AngularJS finishes processing and rendering them.

69. How do you handle user authentication in AngularJS?

Ans:

Sign-In Form: Create an HTML form for user logins. AngularJS directives like ng-model bind form inputs to model variables.

Token-based Authentication: Use JSON Web Tokens (JWT). The server creates a token that the client stores (e.g., in local storage or a cookie) after authentication. API authorisation requests include the token.

Authentication Interceptor: Intercept outbound API requests using an AngularJS HTTP interceptor. The interceptor may add the authentication token to request headers so the server can check user authorisation.

Handling Authentication Responses: Update client-side application state based on server answer. If the login succeeds, save the token and update the user’s authentication status. Display error messages if authentication fails.

Logout: Provide a logout method that clears the user’s authentication token and sends them to a login page.

70. Explain the concept of one-time binding in AngularJS.

Ans:

One-time binding in AngularJS is a feature that lets you improve efficiency by creating a binding that updates just once rather than constantly looking for changes. When data doesn’t need to be updated dynamically or when you want to lower the number of viewers in your application, it is very helpful.

71. What is the role of the $filter service in AngularJS?

Ans:

Data filtering, formatting, and transformation are all made much simpler in AngularJS apps thanks to the $filter service. It comes with a set of pre-made filters and lets programmers to make their own so that data in views, controllers, and services may be manipulated in various ways.

The $filter service is responsible for applying different filters to data in order to alter and format it before to being shown to the user. AngularJS comes with a wide variety of in-built filters, including case, lowercase, currency, date, and orderBy.

72. How do you implement caching in AngularJS?

Ans:

To reduce the number of API requests and boost speed, an AngularJS application may take use of caching by storing and retrieving data from the cache using AngularJS services and methods. Multiple options for caching implementation are available in AngularJS.

The $cacheFactory service is one option, as it facilitates the generation and administration of caches tailored to specific needs. Instead of repeatedly requesting data from the server, you can just store it in the cache and access it with a different key at a later time. You may tailor-make caches for your app’s data retrieval requirements with the help of $cacheFactory.

73. Explain the concept of AngularJS directives’ restrict option.

Ans:

The restrict option is used in directive definitions in AngularJS to provide restrictions on how the directive may be used in HTML templates. Element, attribute, class, and comment directives may all have their application modified in this manner. The restrict option takes a character string that limits the possible applications.

74. What is the role of the ng-keypress directive in AngularJS?

Ans:

In AngularJS, the ng-keypress directive is used to record keyboard events and carry out certain behaviors or actions in response to those events. It enables you to real-time handle user input by allowing you to attach a function to a keyboard press event. The input element or any other element that may accept keyboard input should usually be used in combination with the ng-keypress directive.

75. How do you handle dependency injection in AngularJS controllers?

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Dependency injection (DI) is a foundational concept in AngularJS that facilitates the easy management and injection of dependencies into controllers. Modular, testable, and reusable code are all fostered by DI’s assistance in decoupling components.

76. Describe the differences between AngularJS factories and services.

Ans:

In AngularJS, factories, and services are both used to produce reusable components, but their implementation strategies are different. While factories are functions that yield objects, services use the new keyword to create instances of objects. The production and manipulation of objects are more flexible in factories.

77. How does dependency injection work in AngularJS?

Ans:

When implementing the dependency injection design pattern in AngularJS, components (such as controllers, services, etc.) expose their dependencies rather than creating them on their own. In AngularJS, the injector system resolves and injects the required dependencies when a component is instantiated..

78. What is the concept of “scopes” in AngularJS?

Ans:

Scopes in AngularJS are objects that act as the glue between the controller and the view. They enable two-way data binding, allowing changes in the model or the view to automatically update each other. Scopes are organized in a hierarchical structure, where child scopes inherit from their parent scopes. This allows for better separation of concerns.