Angular 5 Interview Questions

Angular 5 has become a popular framework by a large number of enterprises and the same has resulted in the requirement to have potential candidates in the same field. It is most suitable for the end-users for desktop applications but it also has a wide range of features for web applications as well. In this article, you will get to learn the most precise and relatable Angular 5 interview questions and answers that will ultimately help you crack any of the interviews.

Most Frequently Asked Angular 5 Interview Questions and Answers

There are a lot number of new features that are included in angular 5 which makes them ideal for the front end development.

  • It allowed creating acceptable applications by using ARIA enabled components
  • It provides the support for command-line interface tools and this can be used for adding multiple components
  • It allows creating high performance and complex timelines with less coding
  • To build an impactful and powerful web application it can be used also it is widely considered in cross-platform development
Factor of comparison Angular 4 Angular 5
Typescript Typescript 2.1 and 2.2 are supported. Typescript 2.5 is supported.
Advantages It is faster and compact To build optimizer
Preservation There are no potential restrictions for unnecessary tabs or white spaces. Tabs and white spaces can easily be restricted.
HTTP It is the model of angular HTTP It is a module of HTTP client with angular HTTP
To route This feature remained absent in the earlier versions. A developer can easily track the fruit of events.

One of the core features of angular 5 is directives which allowed the developer to write the new and application-specific HTML syntax. it also refers to a function that can be executed by the angular 5 compilers when it finds a similar structure in DOM.

Basically, they are of three major types
  • Attribute directives
  • Component
  • Structural directives

The @viewchild directive is used to access the elements in a direct view. You can have a reference with the below presented input element as- <input #uname>

The child directive can be defined and accessed in ngafterviewInit life cycle as- @ViewChild('uname') input;
ngAfterViewInit() { console.log(this.input.nativeElement.value); }

Transpiling in angular 5 refers to the process of converting any typescript in JavaScript using the corresponding compiler. Typescript is also used to create the codes in angular applications where the code is internally formed and transpired into JavaScript. In angular 5 traceur compiler is utilized for the conversion of typescript to JavaScript facilitating the browser to understand easily.

One of the most important and core concepts in Angular 5 is data binding which allows various instances to communicate together in between a component and DOM. it also makes easy to define the interactive applications without worrying much about pushing and pulling the data.

There are three major types of data binding in angular 5 which are
  • From component to DOM (interpolation)
  • From DOM to the component (event binding)
  • Two-way binding

The declarative form which supports the passing of messages between publisher and subscriber for the application is known as observables. They are also used for event handling and asynchronous programming along with having values other values as well. For such instances, you can define a function for publishing the values but it will not be executed until any of the consumers subscribes to it. Once it is done the subscribed consumer will receive notification until the function gets completed or until they unsubscribe from the application.

It is one of the most frequently asked Angular 5 interview questions.

RxJS refers to a library composing the asynchronous and callback-based utility in the codes as functional and reactive style observables. A large number of API like HTTP clients and so on, produce and consume them as observables and also use operators for processing the observables. For example, you can easily import them along with the operators for using over an HTTP client.

It is mentioned below-
import { Observable, throwError } from 'rxjs';
import { catch error, retry } from 'rxjs/operators';

It also helps in-

  • Composing the multiple streams
  • Filtering the streams
  • Mapping values to various types
  • Iteration throughout the values

Subscribing in angular 5 refers to an observable instance which starts the publishing of values when anyone subscribes to it. To do the needful one has to subscribe by calling the same as a function method for the same instance and passing the observer object to receiving various notifications. whenever this method is called upon it conducts an independent execution for all the observable instances.

Can you create any of the subscribe function with a simple observable?

It can be done as the observers receive logs messages to the console. One such example is- Creates an observable sequence of 5 integers, starting from 1 const source = range(1, 5);

In angular 5 interceptors refers to the window which the developer generally used to draw potential ground to grow and set global variables. In any of the browser programs, a single global setting is "glass" and in its opposite view Node.js utilizes the element as "Global Ref". Once it is done any sort of data can be used or tagged in the data size. It also facilitates the state oversize where the data can be created in every segment.

Router outlet refers to a directive obtained Sandhya router library and then it acts as a placeholder that marks the spot in any template. The temperature refers to the router if my speaker table to display the component for the specific outlet.

Router-outlet' is more like in component and its syntax is mentioned below.


It is one of the most popular Angular 5 interview questions.

Router link is a directive on the anchor tags which give the entire control to the elements and their navigation parts are fixed one can easily assign the string values to these links as-

<h1>Angular Router</h1>


  <a routerLink="/todosList" >List of todos</a>

  <a routerLink="/completed" >Completed todos</a>




Active router link is a directive that can toggle the CDs classes for router links and binding them as per the current router state.

<h1>Angular Router</h1>


 <a routerLink="/todosList" routerLinkActive="active">List of todos</a>

 <a routerLink="/completed" routerLinkActive="active">Completed todos</a>



// Create observer object

const myObserver = {

  next: x => console.log('Observer got a next value: ' + x),

  error: err => console.error('Observer got an error: ' + err),

  complete: () => console.log('Observer got a complete notification'),



// Execute with the observer object and Prints out each item


// => Observer got a next value: 1

// => Observer got a next value: 2

// => Observer got a next value: 3

// => Observer got a next value: 4

// => Observer got a next value: 5

// => Observer got a complete notification

How to import a module in Angular 5?

In order to import a module in angular 5, you can go to the below-mentioned syntax as-

   import { ModuleName } from 'someWhere';

A pipe is a feature that is used to modify the output present over the template and it is more like something that is changing the string into an upper case for displaying it over the template. It can also modify the date format as per the description. Pipes also the form of data is a basic input and then transform it as per the desired outputs.

A parameter inside the pipe can easily be created by declaring the pipe within itself having a call on and any of the parameter values. If they contain multiple parameters then they are separated by Colons.

Consider a birthday example-

import { Component } from '@angular/core';

selector: 'app-birthday',
template: `

Birthday is {{ birthday | date:'dd/mm/yyyy'}}

` // 18/06/1987
export class BirthdayComponent {
birthday = new Date(1987, 6, 18);

Unit testing alludes to a specific software testing method where individual components are tested for any application. In Angular 5 it is performed using the specific software framework which is used for creating and writing that test and later they are run. It is one of the most popular Angular 5 interview questions.

The root module through which one can bootstrap for launching the vehicle is known as bootstrap in a module which is also known as the app module.

Its default structure is as follows-
/* JavaScript imports */
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';

import { AppComponent } from './app.component';
/* the AppModule class with the @NgModule decorator */
declarations: [
imports: [
providers: [],
bootstrap: [AppComponent]
export class AppModule { }

The service worker mentions a script that runs on the web browser and effectively manages to cache of the application. These Angular 5 interview questions and answers are commonly asked in many interviews.