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AngularJS Interview Questions

AngularJS Interview Questions: After a skill-based AngularJS training is over, students have to appear for job interviews. Providing relevant answers to AngularJS interview question can help in deciding the future of the candidates. Thus, it is highly important to answer effectively during the interview sessions so that participants can find a way to achieve their career goals. This is an article containing AngularJS interview questionnaire. The article has been prepared by AngularJS specialists, AngularJS experts, and AngularJS trainers who have put their hard efforts and best of their knowledge while creating the AngularJS interview questions and answers for freshers, and experience candidates. The questionnaire contains detailed answers covering basic and advanced AngularJS interview questions. Understanding of each question and answer provided in the article would assists job aspirants to crack interviews and discover relevant answers to their doubts or puzzlements. The AngularJS Interview Questions is a summarization of verticals available in the AngularJS technology.

angular js interview questions

About AngularJS

AngularJS is a JavaScript-based open-source front-end web framework. AngularJS is supervised by Google and by a community of individuals and corporations. This community focuses on addressing various challenges that occur while developing single-page applications. AngularJS is a structural framework for self-motivated web apps. With AngularJS, designers know how to use HTML as the template language and it authorizes for the extension of HTML's syntax to pass on the application's components effortlessly. Furthermore, AngularJS is usually related to SPA, that developers can use Angular to build any type of app, taking benefit of features such as two-way binding, templating, RESTful API handling, modularization, AJAX handling, dependency injection, etc.

Angular JS Interview Questions And Answers

1. What is AngularJS?

AngularJS is a javascript framework used for creating single web page applications. It allows you to use HTML as your template language and enables you to extend HTML’s syntax to express your application’s components clearly

2. Explain what are the key features of AngularJS ?

The key features of AngularJS are

  • Scope
  • Controller
  • Model
  • View
  • Services
  • Data Binding
  • Directives
  • Filters
  • Testable

3. Explain what is scope in AngularJS ?

Scope refers to the application model, it acts like glue between application controller and the view. Scopes are arranged in hierarchical structure and impersonate the DOM ( Document Object Model) structure of the application. It can watch expressions and propagate events.

4. Explain what is services in AngularJS ?

In AngularJS services are the singleton objects or functions that are used for carrying out specific tasks. It holds some business logic and these function can be called as controllers, directive, filters and so on.

5. Explain what is Angular Expression? Explain what is key difference between angular expressions and JavaScript expressions?

Like JavaScript, Angular expressions are code snippets that are usually placed in binding such as {{ expression }}

The key difference between the JavaScript expressions and Angular expressions

  • Context: In Angular, the expressions are evaluated against a scope object, while the Javascript expressions are evaluated against the global window
  • Forgiving: In Angular expression evaluation is forgiving to null and undefined, while in Javascript undefined properties generates TypeError or ReferenceError
  • No Control Flow Statements: Loops, conditionals or exceptions cannot be used in an angular expression
  • Filters: To format data before displaying it you can use filters

6. What are the Angular Modules?

The angular modules collectively define an angular application where we can write the angular code.

Modules contain the different parts of an angular application. A module is created by angular.module function in angular.

7. What are the directive scopes in AngularJs?

Three directive scopes are available in AngularJs.

They are:

  • Parent scope – Whatever change you make in your directive that comes from the parent scope, will also reflect in the parent scope, and it is also a default scope.
  • Child scope – It is a nested scope which inherits a property from the parent scope. Also if any properties and function on the scope are not connected with the parent scope directive, then a new child scope directive is created.
  • Isolated scope – It is reusable and is used when we build a self-contained directive. It is only used for private and internal use which means it does not contain any properties of the parent scope.

8. What is the digest cycle in AngularJs?

It is a part of the process of data binding in AngularJs. It compares the old and new version of the scope model value in each digest cycle.

The digest cycle is triggered automatically. We can also enhance the usability by using $apply (), if we want to trigger the digest cycle manually.

9. Explain the differences between one-way binding and two-way binding.

One-way binding is used to bind the data from the model to view without updating the HTML template or view automatically.

Thus in order to update the HTML template, we need to write a custom code which will update the view every time whenever a data is binded from model to view.

Whereas, two-way binding is used to bind the data from the model to view and vice versa(i.e view to model) by automatically updating the HTML template without writing any custom code.

10. Difference between sessionStorage, cookies, and localStorage.

Given below are the various differences.

SessionStorage – The data is stored for a particular session. The data will be lost whenever the browser tab will be closed or after some particular session. Maximum size stored can be up to 5MB.

LocalStorage – The data is stored with no expiration date. The data can only be cleared by JavaScript or by clearing the browser cache. Storage limit is maximum than the sessionStorage and cookie.

Cookies – It stores the data that has to be sent back to the server with some requests. The cookie's expiration varies on the type and duration set from either the server side or client side. Maximum size stored can be less than 4KB.

11. What are templates in Angular?

Templates in Angular are written with HTML that contains Angular-specific elements and attributes. These templates are combined with information coming from the model and controller which are further rendered to provide the dynamic view to the user.

12. In Angular what is string interpolation?

String interpolation in Angular is a special syntax that uses template expressions within double curly {{ }} braces for displaying the component data. It is also known as moustache syntax. The JavaScript expressions are included within the curly braces to be executed by Angular and the relative output is then embedded into the HTML code. These expressions are usually updated and registered like watches, as a part of the digest cycle.

13. What is the difference between $scope and scope in Angular?

  • $scope in Angular is used for implementing the concept of dependency injection (D.I) on the other hand scope is used for directive linking.
  • $scope is the service provided by $scopeProviderwhich can be injected into controllers, directives or other services whereas Scope can be anything such as a function parameter name, etc.

14. What is AOT?

AOT stands for Angular Ahead-of-Time compiler. It is used for pre-compiling the application components and along with their templates during the build process. Angular applications which are compiled with AOT has a smaller launching time. Also, components of these applications can execute immediately, without needing any client-side compilation. Templates in these applications are embedded as code within their components. It reduces the need for downloading the Angular compiler which saves you from a cumbersome task. AOT compiler can discard the unused directives which are further thrown out using a tree-shaking tool.

15. Explain jQLite.

jQlite is also known as jQuery lite is a subset of jQuery and contains all its features. It is packaged within Angular, by default. It helps Angular to manipulate the DOM in a way that is compatible cross-browser. jQLite basically implements only the most commonly needed functionality which results in having a small footprint.

16. What is Dependency Injection in Angular?

Dependency Injection (DI) is a software design pattern where the objects are passed as dependencies rather than hard-coding them within the component. The concept of Dependency Injection comes in handy when you are trying to separate the logic of object creation to that of its consumption. The ‘config’ operation makes use of DI that must be configured beforehand while the module gets loaded to retrieve the elements of the application. With this feature, a user can change dependencies as per his requirements.

17. What is Transpiling in Angular?

Transpiling in Angular refers to the process of conversion of the source code from one programming language to another. In Angular, generally, this conversion is done from TypeScript to JavaScript. It is an implicit process and happens internally.

18. How to perform animation in Angular?

In order to perform animation in an Angular application, you need to include a special Angular library known as Animate Library and then refer to the ngAnimate module into your application or add the ngAnimate as a dependency inside your application module.

19. What is transclusion in Angular?

The transclusion in Angular allows you to shift the original children of a directive into a specific location within a new template. The ng directive indicates the insertion point for a transcluded DOM of the nearest parent directive that is using transclusion. Attribute directives like ng-transclude or ng-transclude-slot are mainly used for transclusion.

20. Explain the concept of scope hierarchy? How many scope can an application have?

Each angular application consist of one root scope but may have several child scopes. As child controllers and some directives create new child scopes, application can have multiple scopes. When new scopes are formed or created they are added as a children of their parent scope. Similar to DOM, they also creates a hierarchical structure.

21. Explain AngularJS boot process.

When the page is loaded in the browser, following things happen:

  • HTML document is loaded into the browser, and evaluated by the browser. AngularJS JavaScript file is loaded; the angular global object is created. Next, JavaScript which registers controller functions is executed.
  • Next AngularJS scans through the HTML to look for AngularJS apps and views. Once view is located, it connects that view to the corresponding controller function.
  • Next, AngularJS executes the controller functions. It then renders the views with data from the model populated by the controller. The page gets ready.

22. What is MVC?

Model View Controller or MVC as it is popularly called, is a software design pattern for developing web applications. A Model View Controller pattern is made up of the following three parts:

  • Model − It is the lowest level of the pattern responsible for maintaining data.
  • View − It is responsible for displaying all or a portion of the data to the user.
  • Controller − It is a software Code that controls the interactions between the Model and View.

23. Is AngularJS extensible?

Yes! In AngularJS we can create custom directive to extend AngularJS existing functionalities.

Custom directives are used in AngularJS to extend the functionality of HTML. Custom directives are defined using "directive" function. A custom directive simply replaces the element for which it is activated. AngularJS application during bootstrap finds the matching elements and do one time activity using its compile() method of the custom directive then process the element using link() method of the custom directive based on the scope of the directive.

24. What is the difference between ngRoute and ui-router?

ngRoute is a module developed by angularJS team which was a part of the core angularJS framework. Whereas ui-router was developed by a third-party community to overcome the problems of ngRoute.

ngRoute is a location or URL based routing, and ui-router is a state-based routing which allows nested views.

25. Difference between ng-bind and ng-model directive.

ng-bind directive has one way data bindings, data flows only from object to UI, not vice versa (i.e. $scope>>view) and ng-model directive has two way data bindings, data flows between UI to object and vice versa(i.e. $scope>>view and view>>$scope).

26. Difference between services and factory.

Factories are functions that return the object, while services are constructor functions of the object which is used by a new keyword.

Syntax:

Factory – module.factory(`factoryName`, function);

Service – module.service(`serviceName`, function);

27. What is Event Handling?

Event handling in AngularJs is very useful when you want to create advance AngularJs applications.

We need to handle DOM events like mouse clicks, moves, keyboard presses, change events and so on. AngularJs has some listener directives like ng-click, ng-dbl-click, ng-mousedown, ng-keydown, ng-keyup etc.

28. Define Factory method in AngularJs.

It is quite similar to service, factories implement a module pattern in which we use a factory method to generate an object which is used for building models.

In a factory, a method object is returned at the end by creating a new object and adding functions as properties.

Syntax:

module.factory(‘factoryName', function);

29. What is SPA (Single page application) in AngularJs?

It is a web application which loads a single HTML page and dynamically updates the page as the user connects with the app.

By using AJAX and HTML a fluid and responsive web app can be created by SPA without invariant page reloads. Through this, we can make responsive UI with no page flicker.

30. What do you understand by dirty checking in Angular?

In Angular, the digest process is known as dirty checking. It is called so as it scans the entire scope for changes. In other words, it compares all the new scope model values with the previous scope values. Since all the watched variables are contained in a single loop, any change/update in any of the variable leads to reassigning of rest of the watched variables present inside the DOM. A watched variable is in a single loop(digest cycle), any value change of any variable forces to reassign values of other watched variables in DOM

Career scopes and salary scale

Every sector in the industry is watching a job crunch. However, when it is about Artificial Intelligence and AngularJS, the need for skilled professionals of AngularJS are at higher side. AngularJS participants having in-depth knowledge and obtained skill-based training are able to discover better career opportunities in the worldwide job marketplaces. Besides, AngularJS has occupied the topmost place in the arena of Artificial Intelligence. A AngularJS participants is expected a minimum salary of 34,000 dollars per annum. However, the salary of an experienced AngularJS expert can reach to its double. The salaries are very reliant upon the location, business, and the company’s requirements.

Conclusion

The article ‘AngularJS interview questions’ has been prolifically answered every advanced AngularJS interview questions. As well, the understanding approach in the AngularJS interview questions for experienced is being intended by our trainers and team of experts. They have tried their top of the familiarity to help professionals in getting answers to all doubts and not clear concepts. Even then, if learners still require more detailing about AngularJS, they may drop in a message to our experts concerning to AngularJS interview questions for experienced professionals. Our trainers would be happy to assist and resolve all your AngularJS-programming issues of the students. Join Angular JS Training in Noida, Angular JS Training in Delhi, Angular JS Training in Gurgaon

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