Angular 4 Interview Questions and Answers

Last updated on Feb 07, 2024
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Angular 4 Interview Questions

Angular 4, released in March 2017, is a JavaScript framework for building apps in HTML, JavaScript, and TypeScript. Angular 4 offers built-in features for HTTP service, animation, and materials. This is an essential topic in the Angular 4 Interview Questions for experienced professionals. The unique feature in Angular 4 is that starting from Angular 4, developers will be able to query ParamMap in the router.

Quick Facts About Angular 4
What is current angular version? Angular 11.0. released on 11th November 2020
Angular4 is Developed by Google
What language does Angular use? TypeScript
When was Angular first released? 20th October 2010
When was Angular4 released? 23rd March 2017
Which is the best free IDE for Angularjs? Sublime Text, Visual Code, Atoms, etc
What is the best Angular version of web development? For the development, Angular 2 and 4 both are good.

Most Frequently Asked Angular 4 Interview Questions

Here in this article, we will be listing frequently asked Angular 4 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.

Q11. What is unit testing in Angular 4?

Unit testing or private testing is used to test the system’s components. This process is s best practice to test small separate pieces of code. If the unit testing depends on any of the external resources such as networks, APIs and databases, then it won’t be listed as a unit test.

Q12. What is ElementRef in angular 4?

ElementRef is basically a class or reference types used for abstraction. The class structure holds the native elements and ElementRef is used to access the native elements

selector: 'sample',
...export class SampleComponent{
constructor(private hostElement: ElementRef) {

ElementRef is used to break the abreaction rather than using specific API DOM like textContent

Q13. What is the use of services in angular 4?

Angular 4 services contain functions or methods that consistently maintain the data of an application throughout its life which implies that data will remain secure and available at all times. The main aim of angular 4 services is to share business logic, data, information, models with several components of angular 4 applications.

Q14. What is the difference between interpolation and property binding?
Interpolation Property Binding
It can be implemented using {}. It can be implemented with [].
It supports the concatenation of string inside a variable. Property Binding does not support the concatenation of String.
Interpolation does not support working with a boolean type. Property Binding supports working with all boolean types.
Q15. What is the difference between pure and impure pipes?
Pure Pipes Impure Pipes
By default, all pipes are pure. It has to be changed from pure to impure.
Used when angular detects a change in value or parameter. Used in every detection cycle independent of changes in value or parameter.

Note: Our aim while creating Angular 4 Interview Questions, is to help you grow as a Angular Developer. The questions mentioned here have been asked by leading organizations during technical rounds of the interview process.

Q16. What is deep linking in angular 4?

In general, deep linking takes a specific page directly without searching and traversing application from the landing page. It helps in generating and getting indexes so that the specific links can be easily searched by the search engines.
Angular 4 support deep linking using ‘#’

Q17. What are the difference between Angular 4 and Angular 5?
Angular 4 Angular 5
Angular 4 is fast and more compact It is widely used to build optimized applications
It is Angular Universal. It is Angular universal as well as state transfer.
Angular 4 uses TypeScript 2.1 and TypeScript 2.2 Angular 5 uses TypeScript 2.5.
Q18. How to send and set cookies in Angular 4?

We can use the ngx-cookie-service node package to save cookies in Angular 4.

Use the following steps:
  • Install the node package with the following syntax:
    npm install ngx-cookie-service –save
  • Now, we have to add the cookies service to app.module.ts as a provider.
        providers: [ CookieService ]
  • Further, continue by importing and injecting it into a component.
    import { CookieService } from 'ngx-cookie-service';
    constructor( private cookieService: CookieService ) { }
    ngOnInit(): void {
    this.cookieService.set( 'Test', 'Hello World' );
    this.cookieValue = this.cookieService.get('Test');

Q19. What is eager loading in angular 4?

There are three types of loading namely eager loading, lazy loading, and preloading. In general, eager loading is a module that needs to import into the Angular 4 application module by importing metadata of @NgModule decorator. Additionally, eagerly loading is useful for small size angular applications in which all feature modules will be loaded before starting of the application.

Q20. What is the difference between JavaScript and ECMAScript?

JavaScript is a programming language designed for web pages. It is developed by Netscape and Sun and it is initiated by Netscape and called LiveScript. It is used to enhance web pages with dynamic and interactive features.


ECMA is an abbreviated form of European Computer Manufacturer's association. In general, ECMAScript is a standard used in scripting languages such as Jscript, JavaScript.

This means a request for the route- and the query parameter can be assigned to a route. Until Angular 2, route parameters were stored in a key-value object and were accessible through standard JavaScript syntax. Do you want to succeed in your Angular 4 Interview Questions and Answers? Read on!

Another unique feature is that the functions that were necessary for animations are placed in their package. This has been done to avoid creating unnecessary bundles of significant size. Until Angular 2, these functions were offered as part of the core module and were always included even if they were not getting used in apps.

In angular 4, the use of decorators is done extensively for compiling the code. There are four types of decorators – Class, Property, Method, and Parameter.

Type security and speed ngc-Compilerhave improved in Angular 4 as compared to Angular 2. If you are scrolling on the web for angular 4 interview questions and answers pdf, then this guide will gonna help you.

Reviewed and verified by Umesh Singh
Umesh Singh

My name is Umesh Singh having 11+ experience in Node.JS, React JS, Angular JS, Next JS, PHP, Laravel, WordPress, MySQL, Oracle, JavaScript, HTML and CSS etc. I have worked on around 30+ projects. I lo...