Angular 5 Interview Questions Answers

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Angular 5 Interview Questions AnswersAngular 5 interview questions answers help job seekers and freshers to have basic and advance knowledge Angular 5 framework. Experienced also can take the advantage of Angular 5 interview questions answers post.  I got the feedback from many Angular 5 developers that they found Angular 5  interview questions answers post very helpful for succeeding in and exam Angular 5 test.  Angular 5 is not a programming language. Angular is a client-side framework. It means user's browser is responsible for  executing it rather than web server thus reducing the overhead burden on web server. For developing  mobile apps and desktop applications Angular is supposed to be popular and powerful framework.

The initials Angular interview questions let you know basic concepts of Angular framework which are helpful to get stronger in the Angular framework  specially for beginners. The list of Angular questions answers are like a Angular tutorial which makes the reader strong technically in Angular.


1. What is Angular 5?

For developing  mobile apps and desktop applications Angular is supposed to be popular and powerful framework. Client applications in HTML and either JavaScript can be used for developing applications. Angular's important feature is "TypeScript" language. TypeScript is converted into Javascript by compiler.  For Single Page Application(SPA) Angular is the best approach.

2. List the new features of  Angular 5.

  • Some tools have been improved.
  • Pipeable Operators have been introduced in Angular.
  • Ahead of Time (AOT) is improved to be on by default
  • Angular 5 supports latest version of Typescript.
  • ActivationStart and ActivationEnd new events now are part of Router.
  • Improved Number, date and currency pipes.

3. List Prerequisites for Angular 5.

You must to have Node.js installed.
You must to have NPM (Node Package Manager) installed.

4. Define CLI in Angular 5.

Angular CLI stands for Angular Command Line Interface. CLI is a command line interface tool equipped with special commands which  helps to create and manage a new angular app by writing the command on interface. New app created by CLI is not limited to be executed in default mode.

5. List the building blocks of Angular 5.

  • Dependency Injection
  • Modules
  • Services
  • Routing
  • Data Binding
  • Component
  • Template
  • Directives

6. Define Bootstrapping in Angular 5.

The ng-app directive describes  the root of  the Angular application and indicate to Angular to read the HTML within that root and render the HTML for presentation on UI.  This process  is called the bootstrapping process.

Angular creates a root AppComponent called bootstrap for inserting into starting or host web page.

7. What is the Role of "ngOnChanges" componenet?

Whenever a change happens to the data that was bound to an input then ngOnChanges(Angular Life Cycle Component) get executed.

8. What Is entry component in Angular 5?

ComponentFactoryResolver creats a component dynamically called entry component which defines others components. You can specify an entry component by bootstrapping in the Angular module or you can specify an entry component by routing definition.

9. List Component Life Cycle In Angular.

  • Create
  • Render
  • Create and render children
  • Check for bound data changes and re-render
  • Destroy

10. What is Node js?

Node.js is an open source server environment designed for using the javascript on server and it runs on various platforms  like Windows, Linux, Unix etc.  Node.js uses asynchronous programming.

11. Define Directives in Angular 5?

AngularJS Directives are the extended HTML attributes which change the behavior of application. These directives are prefixed with ng.

  • The ng-app directive initializes an AngularJS application.
  • The ng-init directive initializes application data.
  • The ng-model directive binds the value of HTML controls (input, select, textarea) to application data.

12. What is TypeScript?

TypeScript is a superset of Javascript. TypeScript is more powerful than javascript because it supports many useful and powerful features which javascript does not have. TypeScript supports string type feature it means you can declare variable with data type thus makes easy to catch data mismatch error. TypeScript also supports OOps concepts means you can declare class, Interface, constructor etc.

13. What is Single Page Application (SPA)?

In SPA approach pages are loaded from server without post back and a single shell page loads all pages in master pages.

14. How can SPA be implemented in AngularJS?

By using Angular routes SPA can be implemented.

15. What is dependency injection?

If there is a need for new component with service in Angular then dependency injection fulfill this requirement. Dependency injection can provide new objects(new instance of class) as full formed dependencies. In other words dependency injection is the process where the dependent objects are injected rather than being created by the consumer.

16. What are the benefits of dependency injection?

Dependency injection has two major benefits: Testing and decoupling.

17. Define ng-Class and ng-Style.

In ng-Class, loading of CSS class is possible; whereas, in ng-Style we can set the CSS style.

18. What Are Decorators?

Decorators modify class members and functions by adding . metadata at run time.

19. Define @Component and @Directive.

To create a new element in DOM you can use component with HTML template defined in it whereas to change or update existing element you can use directive.

20. List types Of Data Binding in Angular 5.

  • String Interpolation
  • Property Binding
  • Event Binding
  • Two-way-binding

21. List component life cycle in Angular 5.

  • Create
  • Render
  • Create and render children
  • Check for bound data changes and re-render
  • Destroy

22. How Do We Import A Module In Angular 5?

Use below syntax:

import { ModuleName } from ‘someLocation’;

23. What is $event In Angular 5?

$event is a reserved keyword that represents the data emitted by an event (event data).

24. What Do Double Curly Brackets Are Used In Angular 5?

Double curly brackets are used form data interpolation in Angular 5.

25. What is routing?

Routing means navigating to different  pages based on the option you choose on the main page with no page reloading. The ngRoute module routes your application to different pages without reloading the entire application.

26. What is transpiling?

Browser can not understand Typescript directly so it has to be converted into javascript. So  process of converting code from one language to another is called transpiling. In Angular, Traceur compiler is responsible for  converting TypeScript to JavaScript so that browsers can understand.

27. What is @Inputs and @Output in Angular5?

Input and Output are two decorators in Angular responsible for communication between two components. The @Input decorator is for obtaining the data that is passed from a component. @Output is not just a single thing that can pass data back from child to parent. We have to use EventEmitter to emit the event to the parent so that parent can capture the exposed event and retrieve data. We’ve to combine @Input decorator to pass the initial data to the child component and get back the updated data using @Output decorator and Event emitter.

28. What Are Components in Angular?

Components are the most basic building block of a UI in Angular applications and it controls views (HTML/CSS).
A Component consists of the following:

  • Template − This is the HTML content which is rendered and displayed on application UI.  This also includes the binding and directives.
  • Class − Typescript supports OOps so you can create a class with its member variables and and members methods. This has the code which is used to support the view.
  • Metadata − This has the extra data defined for the Angular class. It is defined with a decorator.

29. What is a module?

A module consist of components, directives, pipes and services which works together as a single unit. A module can be combined to another module to create a application.

30. What is NgModule?

An NgModule is a TypeScript  class marked by the @NgModule decorator. @NgModule takes a metadata object that tells Angular how to compile and run module code.

31. What is a Service in angular 5?

Angular service is a class that encapsulates some methods like GET/POST/PUT and provides it result as a service for across your application.

32. What Is Angular Singleton Service?

Singleton service means whose instance is created only once and available in whole application. It can be created in two way
1. Include the service in the AppModule
2. Declare that the service should be provided in the application root.