Top Angular 2 Interview Questions and Topics

Did you know that Angular was developed by the same Angular team at Google that made AngularJS? It has been written in TypeScript and can help you create SEO-friendly web applications. Angular 2 is an open-source, TypeScript-based JavaScript web application framework, which is free and will help you build web applications in HTML and JavaScript.

This article focuses on Angular 2 interview questions, and we’ll also discuss some sample Angular 2 interview questions and answers that’ll help you with your prep.

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In this article, we’ll learn:

• Sample Angular 2 Interview Questions and Answers for Freshers
• Sample Angular 2 Interview Questions and Answers for Experienced Developers
• Topics Asked in Angular 2 Interview Questions
• Angular 2 Interview Questions for Developers
• Advanced Angular 2 Interview Questions
• FAQs on Angular 2 Interview Questions

Sample Angular 2 Interview Questions and Answers for Beginners

Here are a few sample Angular 2 interview questions and answers to get you started if you’re a beginner:

Question 1: Differentiate between Angular 2 and AngularJS?

Here are some differences between AngularJS and Angular 2:

Question 2: What is routing in angular 2?

Routing helps us create unique URLs for different kinds of content in our application and develop single-page applications. Using routing, we can redirect our users to pages relevant to them based on their choice on the main page. A route is that unique part after the URL’s hash sign (#). Routes in Angular 2 help show several contents based on the route taken.

Question 3: What are the types of modules in Angular 2? How many of each can an application have?

There are two types of modules in Angular 2: root and feature modules. An application can have several feature modules but only one root module.

Sample Angular 2 Interview Questions and Answers for Experienced Developers

Here are some sample Angular 2 interview questions and answers that’d be more of interest to you if you have some experience: 

Question 1: What’s the purpose of the polyfills.ts file?

The purpose of the polyfills.ts file is to make the user application compatible with different browsers and help users with the necessary environmental setup required for ES6., using which we usually write code in Angular 2.

Question 2: Explain services and their features in Angular 2?

Services offer modularity, more compartmentalization of concerns, and extract any common functionalities out of components. Adding services to your Angular 2 applications will make your components free from the data access code. Some features of services are:

• Only a single instance of any service will exist in the entire application.
• Services can return data in the form of promises and observables.
• It is decorated with the help of @Injectable() decorator

Question 3: Name some component-specific hooks in Angular 2 and state what they do.

Here are some component-specific hooks in Angular 2: 

1. ngafterContentinit works to initialize the component content.
2. ngafterViewinit works to create the component view.
3. ngAfterConctentChecked works to check the binding of external content.
4. ngAfterviewChecked works to check the component view’s bindings.

Topics Asked in Angular 2 Interview Questions

In this section, we’ve listed several of the top basic concepts on which Angular 2 interview questions are asked. Practicing these fundamental Angular 2 topics will help you assess your preparation:

1. In Angular 2, define and describe: 

• CLI
• Routing
• Components
• @Outputs
• Modules
• Dependency Injection
• Traceur compiler
• Deep linking 
• String interpolation
• Directive
• Event emitters
• RouterOutlet 
• ViewEncapsulation
• Pipes
• RxJS
• Lazy Loading
• AOT compilation
• Router-link directive
• Filters
• Hooks
• rootScope
• Promises 
• Observables
• Decorator
• Provider 
• Services
• PathMatch in angular routing
• Resolver 
• Activatedroutesnapshot 
• Router state 
• Gulp 
• HammerJS 
• Arrow function
• BASE HREF 
• Subscribe 
• Entry component 
• Internationalization in angular
• Angular material design
• Angular UI
• ECMAScript 
• Flex layout 
• SPA 
• Hidden property 
• Primeng@input 
• @output 
• Tree shaking
• The factory method 
• Routing 
• Bundling 
• Shadow dom

2. What is the difference between: 

• constructor and ngOnInit
• @injectable() and @inject()
• directive and component
• Observables and Promises
• service() and a factory()
• annotation and decorator 
• templateUrl and template
• property binding and event binding
• lazy loading and eager loading
• ng-model and ng-bind
• declarations and entryComponents
• rootScope and scope

3. Explain:

• tsconfig.json file
• package.json file
• polyfills.ts file
• systemjs.config.json file
• app.module.ts file
• Angular 2’s hidden property

Angular 2 Interview Questions for Developers

1. What is the use of:
   a. package.json
   b. tsconfig.json
   c. Codelyzer
   d. Pipes
2. Which page will be called first when page rendering is done for the first time?
3. Talk about all the directives supported by Angular 2.
4. Would you say Angular Modules and ES modules are different or the same?
5. What technique makes use of Angular 2 for two-way binding?
6. Explain the process of loading a page that contains an Angular 2 based application.
7. How can we optimize an application’s performance in Angular 2?
8. Can we automate the process of porting Angular 1 code to Angular 2?
9. How would you define custom typings if you want to avoid editor warnings?
10. What are some security threats associated with Angular 2?

Advanced Angular 2 Interview Questions

1. Using Angular 2, explain how we can convert:
   a. An input to all lowercase
   b. An input to all uppercase
   c. An input to all titlecase
   d. A substring from a string
   e. A string into a date
   f. A string into a currency
   g. A string into a percentage

2. When does the following event get called in Angular 2:
   a. ngOnChanges
   b. ngOnInit
   c. ngDoCheck
   d. ngAfterContentInit
   e. ngAfterContentChecked
   f. ngAfterViewInit
   g. ngAfterViewChecked
   h. ngOnDestroy 
3. What Life Cycle Event checks if the Dom is completely loaded in Angular 2?
4. Which decorator is responsible for creating services in Angular 2?
5. How would you redirect to 404 or some other path, given that the path does not exist in Angular 2?
6. How would you display an error message from the backend in Angular 2?
7. How would you make a singleton service in Angular 2?

FAQs on Angular 2 Interview Questions

Q1. How old is angular 2?

While the Beta version of Angular 2 was released in December 2015, the final version was released in September 2016.

Q2. What are lifecycle hooks, and why is it important?

Lifecycle hooks are important functions called at some specific points during a component lifecycle in architecture-based Angular applications.

Q3. What are some of the best IDEs for Angular 2?

Angular IDE, Webstorm, and Visual Studio Code are some of the best Angular IDEs for Angular 2. Sublime Text, Brackets, and Atom are also good options available as IDEs for Angular 2.

Q4. State some advantages of Angular 2 over Angular 1.

Some advantages of Angular 2 over Angular 1 are: Angular 2 is not just a language; it is also a platform. The performance and speed of Angular 2 are better than that of Angular 1. Angular 2 allows flexible routing with the help of lazy loading features. Angular 2 implements web standards. You won’t lose the functionality of a standalone controller and $scope. It has a simpler DI (Dependency Injection). With Angular 2, you will get the perks of Typescript and ES6.

Q5. What is deep linking in Angular 2?

Deep linking is a URL process that helps with web or app indexing so search engines can crawl these links comfortably and take users to a particular page or specific content without having to cross the application from the homepage

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