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AngularJs Questions and Answers for Interview Preparation

Angularjs interview questions

If you are someone who is looking for a fruitful career in the tech industry or have already secured yourself an interview, it is time to hone your answering skills. When companies look for hiring good AngularJS developers, they look for in-depth knowledge of the subject. Even though every interview and interviewer is different, there are a few questions that are very popular among interviewers to check your skills. We have compiled a list of AngularJS interview questions and answers for freshers to help you crack that interview. 

Q1: What is the Data Binding process?

Ans: Data binding is the automatic syncing of data between the view and the model components. AngularJS uses ngBind and ngModel in directives to achieve this. This ensures that the view synchronizes with the model at all times. 

Data binding has two ways: One-way and Two-way data binding

  • In one-way data binding, changes in the model are reflected in the view but changes in the view will not reflect in the model. It is unidirectional. Either you can bind the data from view to component or from component to view. 
  • Whereas, the two-way data binding works both ways. When the model is updated, it is reflected in the view and vice-versa. 

Q2: Can you explain $scope, scope, and directive scopes in AngularJS?

Ans – In AngularJS, $scope is used when there is dependency injection, and scope is used for directive linking. Scope binds the view with the controller and $scope helps in the interaction between the application controller and the view. 

AngularJS has 3 directive scopes: Parent, Child, and Isolated Scope. 

  • Parent scope is a default scope. All the changes that are made in the directive coming from the parent scope appear in the parent scope. 
  • In the Child scope, all the properties are inherited from the parent scope directive. This is a nested scope. A new child scope is made if there is no connected function. 
  • The isolated scope is independent of the Parent scope. This reusable scope is used for building self-contained directives. 

Q3: Can you explain the directives in AngularJS?

Ans – Directives are used to extend HTML elements and DOM elements’ behavior. Through a prefix ng, it tells the compiler what specified behavior is to be attached to the DOM element. AngularJS has built-in directives which can also be used to build user-defined directives. The built-in directives are: 

  1. ngApp – It is the most important directive and is used to mark the starting of the AngularJS app to the AngularJS HTML compiler. This is to be written first before any other directives. 
  2. ngBind – It is used to bind model variables with HTML controls and HTML tags 
  3. ngModel – ngModel directive is used in HTML controls like <input type=’text’/>. It is used in data binding because it provides a binding behavior between values. 
  4. ngRepeat – It is used to repeat HTML statements
  5. ngClass – It is used to add or remove CSS classes on HTML elements
  6. ngInit – ngInit is used before initializing application data variables
AngularJs built-in directives

Q4: Using core AngularJS functionality, list 3 ways to communicate between modules.

Ans – Well, some of the common ways to communicate between modules using AngularJS functionalities include using services and events. We can also communicate by assigning models on $rootScope. Apart from this we can communicate directly between controllers by using $parent, $$childHead, $$nextSibling, ControllerAs, etc.

Q5: What do services represent?

Ans – Services are single objects. They carry out tasks they are created for which is typically a well-defined, narrow purpose. We can create a service for data that is not associated with any view. Using dependency injection the services are wired together to interact and help the framework in sharing the code across the app. 

Q6: What are the easily testable means of communication between modules?

Ans – Services can be easily tested. Events can also be tested easily. They are usually instantiated in the unit testing controller For $rootScope testing of events, it must be injected into the test. $rootScope is testable against arbitrary models. Direct communication between controllers can also be tested. However, the expected results should be mocked otherwise controllers would need to be manually instantiated. 

Q7: What is the purpose of interpolation in Angular?

Ans – Interpolation is the binding of data by embedding expressions to text nodes and attributes. The compiler matches the attributes and text during compilation. In AngularJS, $interpolate built-in service is used to check if there is any markup that has embedded expression. If there is, they are updated and registered as watches. 

Let’s see some more interview questions for AngularJs that can help you get a Job.

Q8: How to integrate AngularJS with HTML?

Ans – Using the <script> tag in the HTML head section, we first bind the AngularJS library to the HTML page and then bootstrap the AngularJS app using ngApp directive 

Q9: Describe how e2e testing works for AngularJS apps.

Ans – E2e testing is testing the app from start to finish and determine whether all components are working together or not. e2e testing acts as a safety net that catches issues related to integration and flow in the app. Protractor is a NodeJS app built by the AngularJS team to help developers simulate user interactions and test the app. 

Q10: When scope is terminated, it fires two “destroy” events. What are they?

Ans – The two “destroy” events fired on scope termination are $destroy and jqLite / jQuery event “$destroy”. The former is associated with components like link functions or controllers and the latter is associated with the removal of the nodes which may happen without scope teardown. 

These are just a few questions that you should have answers ready for apart from these basic AngularJS interview questions : 

  • Define AngularJS and its features
  • Define Scope
  • How to boot AngularJS
  • What is SPA, etc

Conclusion

These are some most common AngularJS interview questions and answers asked. Apart from these, there are several web Developer Interview coding Questions and Answers that you can be asked including questions about your personal interests and experiences.  The interviewer tries to evaluate your technical skills as well as your abilities as an employee, as a team member, and as an individual. So you should also focus on sharpening your interpersonal skills as well before your interview along with your technical skills.

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