Top 10 Angular Interview Questions For 2021 And Their Answers

Introduction

Angular is one of the most popular platforms for developing scalable web applications. It is built on TypeScript and functions as a component-based framework. Angular offers one of the best collections of integrated libraries that implement features such as client-server interaction forms management and routing.

Possessing a number of dev tools for building, testing, and updating code, it was created to simplify updating and scaling as much as possible. Angular’s ecosystem promotes constant updates for the framework itself and boasts of a community of over 1.7 million developers on GitHub.

Essentials of Angular

Let us check some essentials of the Angular framework that are very important to remember and revise. These will also help answer most of the common or recurring basic Angular interview questions as well as a few Angular interview questions for experienced professionals.

Being aware of essentials such as component types, templates, and classes or having a good foundation will provide confidence to candidates and help answer most Angular questions.

Components

Components in Angular can be considered as building blocks that help develop an application. They are composed of TypeScript classes with @component() decorators, CSS styles, and HTML templates. The decorators are used for specifying Angular-centric information.

Read about: HTML and CSS books that every developer should read in 2021

Here is an example:

@Component({
  selector: 'example',
  template: `
    <h2>example</h2>
    <p>This is an example component!</p>
    `,
})
export class exampleComponent {
  // The code in this class drives the component's behavior.
}

Templates

All the components have HTML templates that declare how the components are rendered. These templates are defined inline or by file paths. Angular expands the function of HTML through additional syntaxes and allows the insertion of dynamic values from the components.

How does Angular behave when the component’s state changes? Angular updates the rendered DOM automatically. Insertion of dynamic texts is one of the important applications of this.

Here is an example:

import { Component } from '@angular/core';
@Component ({
  selector: 'hello-world-interpolation',
  templateUrl: './hello-world-interpolation.component.html'
})
export class HelloWorldInterpolationComponent {
    message = 'Hello, World!';
}

Dependency Injection

Dependencies of TypeScript classes are declared by dependency injections. Angular takes care of the instantiation and allows users to code in a testable and flexible manner. For defining the logger class, the logger.service.ts containing the writeCount function is used. This logs numbers into the console.

import { Injectable } from '@angular/core';
@Injectable({providedIn: 'root'})
export class Logger {
  writeCount(count: number) {
    console.warn(count);
  }
}

Here are some of the important first-party libraries offered by Angular:

• Angular Router
• Angular HttpClient 
• Angular Forms
• Angular PWA
• Angular Animations
• Angular Schematics

Top 10 Angular Interview Questions and Answers

We covered some of the basics of Angular that can help in many common Angular questions for interviews. Now, let’s check the most important Angular interview questions and answers for experienced candidates.

1. What is the difference between Angular and AngularJS?

The main difference between the two is that Angular uses TypeScript while AngularJS is completely based on JavaScript. Angular also supports mobile optimization and is mobile web development friendly. Angular allows users to build SEO-friendly applications while also being backward compatible. Angular is further based on components, directives, and modules, unlike AngularJS.

2. What are some important features of Angular in brief?

Angular runs on component-based infrastructure and applications are built as components that are independent of each other. It uses Angular CLI to create, test, and integrate parts for applications. Angular CLI is used for the end-to-end automation of the development process.

It supports complex animations and dynamic visuals that do not require extensive coding. It promotes automated code-splitting and only loads the code needed to render specific views. Angular is great for cross-platform development and responsive UIs across multiple clients.

3. What are directives?

Directives are used for writing custom application-specific HTML syntaxes. These new sets of rules are written using DOM while the Angular compiler identifies the new HTML syntax, followed by executing the functions of the directive. There are three kinds of directives in Angular, including component, attribute, and structural.

Here is an example of a structural directive:

<div *ngIf = “example” class=”id”>{{example.id}}</div>
<ul> <li *ngFor = “Print example list”>{{example.id}}</li> </ul> 

4. Describe what AuthGuard is.

AuthGuard can be defined as a class that implements the CanActivate interface. This decides whether the user can access any specific path, page, or route inside the application. AuthGuard is fundamentally used for authorization or authentication-based controls.

5. What is the ngModel inside Angular?

ngModel can be referred to as a directive that binds select, input, and textarea. ngModel also stores the user values inside variables that can be used whenever these values are required. This is especially useful during form validations.

6. What is a transpiler in Angular?

Transpilers take code and convert it into code for other scripts. In Angular, the TypeScript compiler is the transpiler that converts the code into JavaScript. This process of code conversion is also known as transpiling.

7. What is Angular Ivy?

Angular Ivy is the codename given to Angular’s rendering and compilation pipeline. The new runtime instructions and compiler are used by Angular’s new releases by default instead of the older View Engine.

8. How can RxJS be used in Angular?

RxJS is very useful for reactive programming that uses observables to compose callback-centric code or asynchronous code easily. It allows users to implement the observable type that fills in till the type is integrated into the languages or a browser supports it.

Find out about the difference between Angular vs React in this blog.

9. What is the MVVM architecture composed of?

MVVM architecture is composed of Model, View, and ViewModel, being able to remove tight bindings between components easily. This architecture is great for sub-directories to refer to observables and not directly to parents.

10. What is data binding?

Data binding can be described as a valuable feature that allows communication to be established between the components and DOM. It simplifies specifying of interactive or dynamic applications without needing to worry about data pulling or data pushing among templates or components.

There are four types of data binding in Angular:

• Two-way data binding
• Property binding
• Event binding
• String interpolation

Frequently Asked Questions

Key Takeaways

One can easily crack Angular interviews by having a strong foundation in Angular and practicing building applications of this framework. Candidates can additionally check the many available questions and answers that are based on Angular and development with Angular.

With enough revision of the top interview questions for Angular alongside solving Angular coding questions, it will be easy to sail through any Angular interview.