Angular 7 interview questions and answers

Angular has been used in the market with the initial version of Angular JS 1 and now it’s rewritten with the latest version called Angular 7. Angular 7 is the most stable version from Angular and it is more advanced with new features and bug fix options which optimizes the performance. The Angular 1 versionis supported by JavaScript, whereas Angular 7 is supported by Typescript. Angular 7 is used as a part of numerous businesses. Angular 7 expertise is relied upon to develop by more than $5 billion by 2020, from just $180 million, as per Angular 4 industry gauges. Here is some advanced Angular 7 interview questions and answersthat may help you take your career to a new level. It is helpful for both freshers and experienced persons who are looking for a challenging job in reputed companies. The anticipated questions from the employer related to Angular 7 is listed below.

1. In Visual studio, which Angular CLI command should we use to build the Angular code every time when any changes are detected?

Answer:- We should use the command 'ng build -watch' to trigger the build automatically whenever any change is detected in the Angular project.

2. How can we implement Azure AD and ADFS authentication in Angular 7?

Answer:- To implement Azure AD and ADFS authentication in Angular 7, we can make use of 'Adal service'.

3. Is there any attribute available in the anchor tag to change the route?

Answer:- Yes, there is an attribute called 'routerLink' which will change the route.

4. How can we attach a token for every HTTP request in Angular 7?

Answer:- Firstly, we have to generate a token and store it in session Storage object. Then we can attach the token in the headers for each HTTP request, with the help of interceptor service.

5. Is it possible to have both Angular route and MVC route using Angular 7?

Answer:- Yes, it is possible using constraints configuration in 'Register routes' method of Route Config class.

6. How to refresh/renew the token after a particular time interval?

Answer:- We can do this with help of ng-Zone.Ng-Zone will run independently and will keep track of time from when we started the application. We need to call the method to generate the token again, once a threshold value is reached.

7. How will you interact withthe component which don't have parent-child relationship, but you need to send data from one to another?

Answer:- We can make use of behaviour subject in this case.

8. In Angular applications, you have a feature of add/edit/filter and most of the fields same in each of the feature. What is the best way to achieve that?

Answer:- We can use 'Dynamic component' for each feature of add/edit/filter and we have to use 'Reactive forms'. If we use 'Reactive forms’, there will be no change in the template but only in 'FormData JSON'.

9. Can we achieve @Input-@navigateOutput to dynamic components?

Answer:- No. We have to make use of variables of the corresponding service in this case.

10. Is there any way to hold the data/obj globally across all components without making use of service variables?

Answer:- Yes, we can make use of the package 'ng2-simple-global' in this case.

11. The router.navigate will not work when,...........?

Answer:- It will not work as expected when we try to navigate the invalid routes or routes which is not configured in the Routing module.

12. How to get the current URL in the address bar using Angular 7?

Answer:- We can get the current URL using the 'Router' module.

13. Where will you do the application Configuration changes for different environments?

Answer:- We canmake use of environment.ts file for this.

14. How to close the visible pop-up on click of the window other than a pop-up?

Answer:-

Using the 'click outside' event in the div pop-up will trigger the click event which is happened outside the pop-up. We can close/hide the pop-up with the help of this.

15. Is it possible to minify the source files without any external package in Angular 7?

Answer:- Yes, it is possible by making some changes in the configuration in angular.json and package.json.

16. Is it possible to call index1.html in our application?

Answer:- Yes, it is possible. We can call index1.html page by changing the setting of 'index' in angular-cli.json file.

17. Can we use one component without sharing its code?

Answer:- If we upload our code in some repository, then we can use the component by downloading it.

18. What is internal functionality of *ngFor?

Answer:- Internally, Angular transforms asterisk syntax (*) into and apply looping to it.

19. What are pure and impure pipes?

Answer:- A pure pipe is executed when a pure change to the input value is detected. An impure pipe is executed when an impure change to the input value is detected.

20. What is the use of main.ts file?

Answer:- It is the main entry point to our application. It compiles the application bootstrapped to run in the browser.

21. What are Polly fills used for?

Answer:- We provide pollyfill script for browser support.

22. What is the difference between template and reactive browser?

Answer:- Template forms depend totally on the template, so if we want to make any complex/big forms, it will make template heavy. Reactive forms depend more on the.ts file and not on the template. We can use reactive forms to build complex and dynamic forms.

23. What is dependency injection in Angular?

Answer:- It is the process where the class asks for dependencies from external resources rather than creating them.

24. What are observables?

Answer:- Observables provide support for passing information between observables and subscribers.

25. What is AOT compilation?

Answer:- It refers to Ahead-of-Time compilation. It converts HTML and typescript code into JavaScript code in the build phase before the browser download and runs that code. This makes the rendering faster in the browser.

26. What is parameterizing pipe?

Answer:-

The Date is – {{ Date | date:"MM/dd/yy" }}

27. What is the purpose of Angular 7?

Answer:- It is used to develop single-page web applications.

28. What is the difference between Promise and Observable in Angular?

Answer:- Promise- Itemits single value. It is not lazy. It cannot be cancelled.

Observable- It emits multiple values over a period of time. It is lazy. We can cancel an Observable by unsubscribing it.

29. What is Chaining pipe?

Answer:- This Chaining operation will be chained using the pipe (|). For example, to display the birthday in the upper case, we need to use the inbuilt date-pipe and upper-case-pipe. It should be,

{{ birthday | date | uppercase }}.

30. What is the command in Angular 7 to start the server?

Answer:- ng serve

31. How can we develop and run Angular 7 apps?

Answer:- We can download visual studio code from https://code.visualstudio.com

32. What is ng-Container?

Answer:- It is a grouping element that doesn’t interfere with styles or layout because Angular doesn’t put it in DOM. It is rendered as HTML command and it renders if the condition satisfies

33. What are the two types of data binding in Angular 7?

Answer:- One-way binding and two-way binding.

34. What are the directives in Angular?

Answer:- Structural directives, Component directives, and Attribute directives.

35. What is the command used to create a component in Angular 7?

Answer:- ng generatecomponent.

36. Name the types of forms in Angular 7.

Answer:- Reactive forms and template-driven forms.

37. What is the role of the map operator?

Answer:- It is used to transform the collection of responses to a collection of a different type.

38. What is Angular 7?

Answer:- It is written in typescript which is a JavaScript-based framework. It is developed by Google. It supports the MVC model or Model, View, and Controller.

39. What are the features of Angular 7?

Answer:-

• It provides dependency injection.
• It provides CSS component encapsulation.
• It provides a unit-testing feature for components.
• It contains templates based on HTML extended version.
• It provides Ajax request by @angular/HTTP.
• It provides building up features for forms @angular/forms.
• It provides routing by @angular/router forRouting.

40. Do we need to import any module for using observables?

Answer:- Yes, we need to import Observable from the rxjs library for using it.

41. What is ng-template?

Answer:- ng- template is used when we make use of structural directives. When we apply the structural directive to an element, Angular move that element in ng-template and renders the element if condition satisfies.

These questions and answers are prepared by experienced faculties and we hope these questions and answers help you to catch your dream job.

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