Top 10 Frequently Asked Interview Questions of Angular 2
Do you want to get a job in Angular 2 development? Or wish to make a switch for being a Java developer to being an Angular developer? Congrats, this article will help you in achieving success if you are preparing for the same. Here are written Angular 2 interview questions and answers provided with a list of the frequently asked questions from the technology. Read on the article and get to know the best ways of learning and revising the significant concepts of the web development framework with ease.
# Question 1
Describe the components of Angular JS in your own words?
Here, the word component means the logical boundary of the functions for the application to be developed. To share the functionality across the element, then we must use layered services. Components consist of a class, metadata, and a template.
- Class- Like the other programming languages, the class contains properties and methods.
- Metadata- It eases the process of facilitating the functionality of a class and also decorates it, i.e., add other features for the broader usage.
- Template- Definition of the HTML view of the application is done with the help of a template.
# Question 2
Why there was a need for Angular 2 framework as we had several before it?
Angular 2 is a new development framework along with being an upgrade of AngularJS. The shortcomings of AngularJS inspired the programmers to develop a new web development framework. The best thing was that it was written from scratch. The main detriments were controllers, DDO, $scope, jqLite, angular.module etc. Also, unlike its previous version, Angular 2 uses components for everything. One can also take the entire application as a component.
Use of TypeScript/ ES6 syntax also makes the web development framework more powerful and back the work with beneficiaries. Evolution and re-designing of other entities of the previous version such as template engine are amongst other upgradations.
# Question 3
If we need to bind the component’s properties with the UI elements values, then what should be used?
Decorators are used in such a scenario. All the properties can be defined inside the component class with @HostBinding by setting metadata on them. Examples are @Injectable one, @Component one used for classes to inject dependencies and for components respectively.
We should use decorators because of the list of the advantages they share
- Decorators support multiple modifications
- Providing support to all templates such as auto-completion, error-checking and graphical designers with the help of the tools has become comfortable with decorators
- Decorators are a separation of concerns
# Question 4
Can RouterLink be used to configure routing in Angular 2?
Yes, the configuration of routing in Angular 2 consists of three main components and one of them is RouterLink. The other two are RouterOutlet which is a placeholder component that is expandable to each route content. Application routes are described by routes
# Question 5
Is it possible to achieve internationalization using Angular 2? If yes, how to do so?
Yes, it can be done with the use of directive i18n. Internationalization, as the name specifies, is the procedure of adapting web applications and software to make the application multilingual and to be used by multiple language users. This directly increases the range of reach of audience ensuring smooth user experience.
# Question 6
Define priming and why is it used in Angular2
Angular 2 have several rich User experience components, and the collection of such components is known as Prime NG. PrimeFaces, popular JavaServer Faces Component Suite, is the parent of this collection and it is developed by Prime Tek Informatics. The main feature is that it is free to use and open source under Apache License 2.0
It has been used in Angular 2 due to its key characteristics of saving time and efforts in the application development process.
# Question 7
What actions can one take to mitigate the security threats of Angular2?
There are some actions that can help in making the usage of Angular 2 safe and secure. We can avoid using unauthenticated external URLs, consider the use of AOT compilation, avoid injecting or using dynamic HTML content to any of the components. Prevention of the REST API from the XSRF attack would also help.
# Question 8
What are angular 2 hooks?
Angular 2 includes a procedural set during the web development process. The term used for this is Angular 2 lifecycle hooks. The process goes from the beginning of the tasks and goes to the end of the application.
Let us take a look at the entities of the process below
- ngOnChanges- With the change in the data-bound property in the process, the process completes with calling of this method
- ngOnInit- With the display of the data-bound properties, the process of initialization begins, and ngOnInit is called after that.
- ngDoCheck- This lifecycle hook is used to detect as well as act on the changes where this web development framework cannot catch on its own.
- ngAfterContentInit- After Angular 2 projects external content into the view of the component, the next step is calling this hook.
- ngAfterContentChecked- In the response after the framework checks the projected content into the component, the calling of this hook takes place.
- ngAfterViewChecked- This hook is called after the checking of the components and child views.
- ngAfterViewInit- Calling of this hook takes place when the initialization of the child views and component’s views by Angular.
- ngOnDestroy- This phase is known as the cleaning phase which comes with the destruction of the component and the directive by Angular.
# Question 9
Explain the difference between ActivatedRoute and RouterState in Angular 2?
ActivatedRoute objects make the current state of the router, and they are built in the form of a tree by the router at the end of each successful navigation. The main characteristic of ActivatedRoute is it's access from anywhere in the application with the help of the routerState property and Router service.
Whereas, on the other hand, the current state of the router in addition to the tree of the currently activated routes and the conventional methods to traverse the route tree is known as RouterState.
# Question 10
How can we handle errors in Angular 2?
The best thing about this web development framework is that it contains the option of error handling. ReactJS catch library and catch function help in doing so. After this, the redirection of errors takes place to the browser’s error console.
Along with the desktop usage, mobile operating systems such as Windows Phone, Android, iOS 6+ and Firefox mobile also support it. Research has been conducted to make the web development framework support to an older version of Android.
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