Most Frequently Asked Angular 10 Interview Questions

Last update: 26 Sep 2021, 10 Questions

So you have already learned about the JavaScript programming language and now want to move on to frameworks. Welcome, you have clicked on the right link. We will help you to get your dream job with the help of some Angular 10 Interview Questions and Answers. Angular still dominates any domain and proved itself an independent one to which anyone can give a thought about their career. React and Angular are the two frameworks that are most widely used by developers. With the help of this platform, you can develop any web and mobile application as it provides the best collection of integrated libraries. These questions mentioned below will help to clear your core concepts of Angular10 and prepare you for the role of a good angular developer.

Top 10 Angular 10 Interview Questions

Here in this article, we will be listing frequently asked Angular 10 Interview Questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.

1. What are the new features of Angular 10?
  • New Date Range Picker- By mat-date-range-input and mat-date-range-picker components you can use this new feature of Angular10.
  • New Default Browser Configuration- In Angular 10 many by default browsers are excluded because of disabling ES5 build in new projects.
  • Keeping up to date with Ecosystem- Some updates like Typescript, TSlib, and TSlint are introduced to keep it updated with the Javascript ecosystem.
  • Warning about commonJS imports- In angular 10 when you will use any dependency that is related to commonJS a warning message will come.
  • Removals- Some of the removals also happen in Angular 10 like it no longer includes ESM5 and FESM5 bundles, old browsers like IE 9 and 10, Typescript 3.6 and 3.7.
  • Bug Fixes and Resolved Issues- Many bugs related to Router, Core, Modules, Compilers, Service Workers got fixed in this version.
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2. Which one is the best out of AOT and JIT?

AOT and JIT both are used for compilation but AOT is superior to JIT because of the following differences-

1. JIT compiles the code just before displaying an application i.e. at runtime. AOT has already compiled the code at the time of building an application, so it doesn’t have to compile at runtime.
2. Due to compilation at runtime loading in JIT is slow. Loading in AOT is fast as code has been already compiled.
3. One can see binding errors at only display time. Template binding Errors can be caught when building your application.
4. The bundle size is higher. Bundle size is half of the bundle size of JIT.
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3. What do you mean by the Wildcard Route?

To handle the invalid URLs in angular applications Wildcard Routes are used.  If a developer is building an application and let’s suppose he/she has entered some invalid URL or deleted some existing URL then we all have observed this default error “404 pages not found”.

  In such cases instead of displaying this error, the user can show a custom error page and that is possible only because of the Wildcard route.

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4. What are the benefits of using HTTPClient in Angular 10?

In Angular10 HTTP Client provides easy to use APIs and many other features like-

  • Testing APIs i.e. Application Programming Interfaces
  • Request and Response interceptors.
  • Typed Requests and Response objects
  • Observable based APIs
  • Handling errors in a better way.

Note: Before using all these features users have to import HttpClient in your angular application.

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5. What are the lifecycle hooks in angular 10?

Lifecycle hooks in angular are callback functions that angular calls when some events take place during the component's life cycle. Let’s understand this concept with some examples-

  • ngOnDestroy- This lifecycle hook is called by the angular when a component is destroyed.
  • ngOnChanges- When a component’s input property changes, angular invokes ngOnChanges.
  • ngOnInit- This lifecycle hook is called when a component is initialized for the first time by angular.
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6. How does Angular 10 integrate with bootstrap?

Some of how we can integrate these two are-

  • Installing bootstrap via npm and importing @import “~bootstrap/dist/css/bootstrap.css”; in src/styles.css i.e. importing bootstrap files in style.css file.
  • By installing jquery and bootstrap via npm and adding scripts and styles to angular.json.
  • In src/index.html users can import bootstrap style and script files.
  • By adding Bootstrap CSS and Javascript files in the <head> section of the index.html file of your angular application.
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7. What is the AOT Compilation?

As we know all the angular applications require a compilation process before displaying them on the browser.

AOT i.e. Ahead of time is also a compiler that converts Typescript code and Angular HTML into javascript code during the build phase of an application and that’s what it makes superior to all compilers as it compiles the code at the time of build process not during the running phase of an application.

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8. How do observables differ from promises in angular?

Both observables and promises deal with asynchronous functionalities in Javascript however differ by one another-

  Observables Promises
1. Observables are lazy i.e. they won't be executed until we subscribe them by subscribe() method. Are not lazy i.e. they executed just after creation.
2. They deal with multiple asynchronous events at a time. Promises handle single asynchronous events at a time.
3. You can cancel the subscription using the unsubscribe() method. They are not cancellable.
4. Observables deliver bugs to the subscribers. It passes the errors to child promises.
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9. What is the difference between annotation and decorator?

Annotation and decorator both have symbol @ but still, they have some different language features-

  Annotation Decorator
1. These are metadata set on the class using the Reflect Metadata Library. Decorator correlates to a function that is called on the class.
2. It is used by the Traceur compiler. It is used by the Typescript compiler.
3. Annotations are hardcoded. Decorators are not hardcoded.
4. Annotation Imports: import {ComponentAnnotation as Component} from ‘@angular/core’; Decorator Imports: import {Component} from ‘@angular/core’;
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10. Could you explain the various types of filters in Angular 10?

Various types of filters can be added by using the pipe character ”|” and then followed by the specific filter. Some of them are-

  • orderBy - This filter orders an array by an expression.
  • uppercase - Set up a string to uppercase
  • lowercase -  Format a string to lowercase
  • number - Present a number to a string
  • date - Present a date to a specified format
  • currency - This filter presents a number to a currency format.
  • filter - Helps to select a subset of items from an array.
  • limitTo - As the name suggests it limits an array or string into a specified number of elements or characters.

Being an Angular Developer is not an easy job. It requires regular practice, staying focused and determined. But I hope these interview questions give you a better understanding of Angular as a framework and a clear picture of what type of questions could be asked in this interview. Just be confident and clear in your words.

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Being an Angular Developer is not an easy job. It requires regular practice, staying focused and determined. But I hope these interview questions give you a better understanding of Angular as a framework and a clear picture of what type of questions could be asked in this interview. Just be confident and clear in your words.

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