Angular 5 Interview Questions 2021

Angular 5 Interview Questions

For building single-page client applications, using HTML and TypeScript, Angular 5 is used. We will discuss the Angular 5 Interview Questions here. The structure depends on basic components .ngmodules are the organization of Angular components which are basic building blocks of the Angular framework. Bootstrapping is enabled by the root module, which has many other modules as features for an application.

  • Angular chooses between different screens to modify the program according to data and logic. It is called a view defined by components.
  • To make the component’s dependencies, make code reusable, modular, and efficient, service providers are injected. Services provide specific functionality not related to views used by components.

The component hierarchy connects the page document object model (DOM) with the help of the root component. The root component is one of the most important elements, and every application has one of them. 

To identify the class below as a component the Component() decorator is used which provides component-specific metadata and templates. 

Angular 5 Interview Question

  • Give yourself a rating on this software.

This question is to test your confidence and how much you know about the subject in your opinion. This can also be a testing factor for them, so answer it honestly. Do not give yourself extra credits or fewer credits. If you take extra credits, they might judge you on your skills afterward, and giving yourself fewer credits may give them the impression that you are not good in the software and may even half-mindedly move further. So be sure to give accurate points to yourself. 

  • When we already had some software, then why was Angular introduced?

The software traditionally used were VanillaJS and jQUERY for the development of dynamic websites by the developers. Due to the increase in the functionality and features, the website became more complex, and the code was difficult to be stored by the developer. The data handling facilities in the jQUERY were very difficult and cumbersome. So we switched to angular for this, which was easy to handle, along with dividing the program into smaller bits known as components. Client-side frameworks allow the development of advanced features.

  • Can you explain some features of Angular.

There are various features that make it suitable for front-end JavaScript frameworks. Some of the major ones are as follows:

  • Progressive web apps: It uses modern platforms to deliver app-like experiences. It has many other benefits like offline, high performance, and quick installation.
  • Desktop: It gives the accessibility to access OS APIs and develop desktop installed apps for the MAC, Windows, and LINUX using the mere knowledge you learned from web plus.
  • Generation of code: The productivity of a framework is given alongside the benefits of a hand-written code. It turns templates into code which is highly helpful for JavaScript of the modern-day, which uses virtual machines.
  • Code split: The component router helps the code to break into small components, so the user only loads the code according to their request of the view. This makes the app’s annual easy to open and less time-consuming.
  • IDEs: You can get instant errors and feedback in popular IDEs and editors due to intelligent code compilers.
  • Accessibility: Accessible applications can be developed using developer guides, built-in test infrastructure, and ARIA-enabled components.
  • Can you tell me some advancements in Angular 5?

Certain tools were developed in the new version for advancements. Some of them are as follows:

  • Supports TypeScript version 2.4.
  • It makes js bundle lighter using tools.
  • By default, AOT (Ahead of Time) is on in the updated version.
  • ActivationStart and ActivationEnd have introduced the router.
  • New features like Pipeable Operators given by RxJ5.5 are supported by Angular 5.
  • Name and explain eight building blocks of Angular 5.

The name of the building blocks of Angular 5 are:

  • Modules
  • Components
  • Templates
  • Metadata
  • Data binding
  • Directives
  • Services 
  • Dependency Injection
  1. Modules: Some values are exported by modules such as in a class. Some tasks are done by a block of code known as a module. One that exports components are a significant one.

export class AppComponent {}

  1. Libraries: Other modules can be in a library of a module. They generally start with the @angular prefix. Angular has many libraries of other modules. The most important is @angular/core which has most of the modules needed.

  2. Components: An element on the screen is shown by a class, basically known as a component. To manipulate the looks and behavior of the elements on the screen, components are used which have many properties. A component can be added, updated, destroyed, and modified according to how the user moves in the application. The modules we use for this are called Life Cycle hooks. Like ng0nInit().

export class blogComponent {}

  1. Templates: The HTML shown on the web page is known as the templates. It actually defines the design or the view.


            <h2>Hero List</h2>

            <p><i> Pick a hero from the list</i></p>


                 <li *ngFor=”let food of foods” (click)= “selectedFood(food)”>



             <food-detail *ngIf=”selected foods” [food]=”selected hero”>


  1. Metadata: It tells Angular how a class should be processed on the screen. Providers are the service provider, and directives are components required to render the components. The metadata, template, and component together describe a view.


           @Component ({ 

           Selector: ‘food-list’,

           templateUr1: [FoodDetailComponent],


           providers :[FoodService]


  1. Data Binding: Data binding is the main feature of any JavaScript framework. The direction to the DOM, from DOM, or both can be bound in four ways:
  • Interpolation display value in li tag
  • The pass from parent to child through property binding
  • The selected food is called event binding when clicked
  • The two-way binding binds property and event binding by the ngModel directive


             <input [(ngModel)]=””>

             <li> {{}}</li>

             <food-detail [food]=”selectedFood”></food-detail>

             <li (click)=”selectedFood(food)”>


  1. Directive: To add the behavior to the DOM this is used. They are of three types:
  • Directive-with-a-template
  • Structural
  • Attribute
  1. Services: A class having any function, feature with a defined, and specific purpose are called services.
  • Define transpiring in Angular.

Although the code is written in TypeScript, it is converted into JavaScript. The process of converting from TypeScript to JavaScript is known as transpiring.

  • Can you give a difference between components and directives?

To add behavior to an existing DOM directive is used whereas the components break the program into smaller parts.

  • Give use of @Input and @Output?

Both of them are used in Angular 5 to pass data. Angular 5 has a parent-child relationship. The @Output is used to pass events to the parent from the child, whereas @Input is used to pass data to the child via the parent. They are generally used in the part from which the information is shared.

  • Define ViewEncapsulation.

If the component can affect the entire application, it is decided by ViewEncapsulation. The three ways to do the above are as follows:

  • Emulated: The component is spread by the styles of HTML.
  • Natives: Styles from other HTML are not spread to the component.
  • Note: The styles are visible to all components defined in a component.
  • Give the process to handle an event in Angular?

An event is anything or any activity that a user does on the web screen/ frontend. E.g.:- mouse click, mouse move, mouse hover, button click. A TypeScript (.ts) is given this event by a view (.HTML) page.

  • Explain the usage of {()}.

Representation of data from a component is done by these sets of brackets {()} when used with an HTML tag. For example, <h1> ({VariableName)} </h2>. Here the TypeScript is VariableName which represents data stored in the template of HTML. This is called String Interpolation.

  • Can you tell the use of package.json in the angular project?

To easily handle the dependencies of the project, it is recommended to use package.json. 

  • Can you tell some lifecycle hooks along with explaining them.

The angular component has a lifecycle as a human from the time of creation to its destruction. For changes to be made in any phase or tap into it, hooks are used. Some of the hooks are as follows:

  • ngOnChanges(): Whenever a change has to be made in one or more properties of the component, this method is called. The previous and current value of the property is stored in the SimpleChanges received by the hook.
  • ngOnInit(): After the ngOnChanges() this hook is called. For initialization of the component and setting its properties. 
  • ndDoCheck(): This gets activated after the ngOnChanges() and ngOnInit(). For the detection and action on the changes that Angular cannot do, it is used. Change detection algorithm can be implemented in this hook.
  • ngAfterContentInit(): After the first ngDoCheck(), it is called. Only after the content is projected does this hook respond inside the component.
  • ngAfterContentChecked(): After every ngAfterContentInit and ngContentcheck, it can be called. After checking the projected content, it responds.
  • ngAfterViewInit(): After initializing the components view or the child’s components view, it responds. 
  • ngAfterViewChecked(): After checking components view, or the child’s components view by the ngAfterViewInit(), it responds. 
  • ngOnDestroy(): To detach event handlers and clean up the code, this hook is used just before the Angular destroys the component. 

Learning a new language is always cumbersome but is always helpful in the long run. It not only makes you successful but also helps you to grow your knowledge. Angular has already proven to be a success in web development and mobile app development. So learning it at an early stage will be beneficial. 

Also read Angular 4 Interview Questions (10+ Sample Answers)

Angular 5 Interview Questions 2021

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