Angular 4

Preparing for you next job interview in Angular 4. We have list down some of the best question and answers that can help you to ace the job.

Q.1 What AngularJS 4?

AngularJS and Angular 4 are different. There is no AngularJS 4.

Angular 4 is the next version after the Angular 2 was released. AngularJS is very different than Angular 4. Angular 4 offers benefits  as

  • Reduced view engine size
  • Support for
    • email validator
    • if/else statement
    • separate package for animation
  • Dynamic loading
  • Addition of angular CLI
  • Typescript usage
Q.2 Can I learn angular 4 directly?

Yes, you can learn angular 4 directly.

Good knowledge of object oriented programming and Typescript will help you quickly master Angular 4 directly.

You can learn Angular 4 at link - https://www.vskills.in/certification/tutorial/web-development/angular-4-tutorials/

Q.3 What is the angular latest version?
The latest in Angular is version 8 released in May, 2019 and the latest updated version of Angular is 8.2.13 as in October, 2019
Q.4 What are the prerequisites to learn angular 4?

The prerequisites to learn angular 4 is good knowledge of object oriented programming and Typescript. Both will help in quickly mastering Angular 4.

You can learn Angular 4 at link - https://www.vskills.in/certification/tutorial/web-development/angular-4-tutorials/

Q.5 What is TypeScript in angular?

Typescript has been selected for Angular development.

Angular is based on Typescript.

Typescript is super set of JavaScript and is maintained by Microsoft.

TypeScript compiles to JavaScript code in any JavaScript engine that supports ECMAScript 3 (or newer).

Q.6 What is the angular 4?

Angular 4 is a web open source Javascript framework, to develop dynamic web applications like single page applications or SPA.

The main advantage of using Angular 4 being, ease of development as it uses HTML like syntax to declare various functionality of a web application.

Angular 4 makes it easy to quickly develop application  for both web and mobile. Angular hides the implementation details and offers facilities for quick application development.

Angular 4 is the next version after the Angular 2 was released. AngularJS is very different than Angular 4. Angular 4 offers benefits as

  • Reduced view engine size
  • Support for
    • email validator
    • if/else statement
    • separate package for animation
  • Dynamic loading
  • Addition of angular CLI
  • Typescript usage

Q.7 Is angular 4 TypeScript?

Yes, angular 4 is based on Typescript.

Typescript is super set of JavaScript and is maintained by Microsoft.

Typescript is a strict syntactical superset of JavaScript and is an object oriented programming language. TypeScript compiles to JavaScript code in any JavaScript engine that supports ECMAScript 3 (or newer).

TypeScript Objects helps to model real world similar to that in OO programming.

Q.8 Why we are using TypeScript in angular?

Typescript has been selected for Angular development.

Angular is based on Typescript.

Typescript is super set of JavaScript and is maintained by Microsoft.

TypeScript compiles to JavaScript code in any JavaScript engine that supports ECMAScript 3 (or newer).

Q.9 Is TypeScript required for angular?

No, TypeScript is not required for angular.

But Angular is based on Typescript. Hence, it will a lot easier in using and grasping Angular, if you are aware of TypeScript.

Typescript is super set of JavaScript and TypeScript compiles to JavaScript code.

Q.10 What is the difference between angular 4 and angular 7?

Angular 4, offers

  • Angular 4 supports TypeScript 2.1 and 2.2 version
  • Angular 4 has reduced size of AOT compiler generated code
  • In Angular 4 animation is in @angular/animation
  • Angular 4 has, Else block in *ngIf introduced
  • Angular 4 has extensive changes in core library


Angular 7 is the third revision since Angular 4.

Angular 7 features

  • Released on Oct, 2018
  • Angular 7 supports Typescript 3.1, RxJS 6.3 and Node 10.
  • CLI Prompts helps users to explore the in-built SCSS support, routing, etc.
  • Increased application performance by to automatically removing reflect-metadata from polyfills.ts file
  • Has virtual scrolling to bind a long list of elements in small packets
  • Support for dragging and dropping items in the list using CDK
  • Can set up a budget limit of final bundle size default lower limit is 2MB and higher is 5 MB updates in Angular Elements
  • support for Node 10, TypeScript3.1, and the RxJS6.3
  • Angular 7 offers Do-Bootstrap and ngDoBootstrap
  • @Output has better error handling
Q.11 What is the use of angular 4?

Angular 4 is a open source Javascript framework, to develop dynamic web applications like single page applications or SPA. Angular 4 is the next Angular version released, after Angular 4 2.

The main advantage of using Angular 4 being, ease of development as it uses HTML like syntax to declare various functionality of a web application.

Angular4 is widely used by software development companies for developing websites and web applications for their clients.

Angular 4 offers benefits as

  • Reduced view engine size
  • Support for
    • email validator
    • if/else statement
    • separate package for animation
  • Dynamic loading
  • Addition of angular CLI
  • Typescript usage
Q.12 What is AOT in angular?

AOT in angular, refers to Ahead-of-Time (AOT) compiler.

AOT converts Angular HTML and TypeScript into JavaScript during build phase before web browser downloads and runs that code

Earlier, Angular used JIT compiler which ran after application is bootstrapped in the web browser. AOT did code analysis, generated code in memory.

With AOT, Angular apps reduced requirement for change detection, or dependency injection during runtime.

Q.13 Should I learn JavaScript before angular?

Yes, you should learn JavaScript before angular.

Angular is framework to generate compiled Javascript apps, easily.

The main benefit of using Angular is the ease of development as it uses HTML like syntax to declare various functionality of a web application.

You can learn Javascript at link - https://www.vskills.in/certification/tutorial/information-technology/dhtml-and-javascript-developer/

Q.14 What is the difference between AngularJS and angular?

The differences between Angular and AngularJS are

  • AngularJS supports MVC architecture whereas Angular uses components and directives
  • AngularJS uses JavaScript and Angular 2 onwards uses Typescript
  • Dependency injection in AngularJS is injected into various functions but in Angular, it is hierarchical dependency using providers, declarations, etc
  • Angular 2 onwards has CLI or command line interface of their own, which is absent in AngularJS
  • For data binding, correct syntax of ng directives for event or property in AngularJS, is needed whereas in Angular it is more intuitive.
  • For heavy data intensive applications, Angular is faster as compared to AngularJS
Q.15 What is required to learn angular?

The required things to learn angular, is good knowledge of object oriented programming and Typescript. Both help in quickly grasping Angular .

You can learn Angular at link

Angular 2  - https://www.vskills.in/certification/tutorial/web-development/angular-2-tutorials/

Angular 4 - https://www.vskills.in/certification/tutorial/web-development/angular-4-tutorials/

Q.16 Does angular 4 require node?

Angular 4 does not require node. But, both are different

Angular 4 is a Open source Javascript framework used to develop client side Javascript apps

Node.js is a server side application which provides server environment.

Angular 4 apps can rum without Node.js

Node.js is used in conjuction with Angular CLI and package management other than server environment.

Q.17 What is the difference between angular 4 and angular 5?

The difference between angular 4 and angular 5, is

  • Angular 4 supports Typescript 2.1 and 2.2 but, Angular 5 supports TypeScript 2.3 version
  • Angular 5 has a build optimizer
  • Angular 5 has Angular Universal State Transfer API to share the application state between server and client side
  • Angular 5 has extensive support of incremental compilation of an application
  • Angular 5 can remove unnecessary white space for reduced bundle size
  • Angular 5 has increases the internationalization across all the browsers and no need for i18n polyfills
  • Angular 5 has exportAs feature
  • Angular 5 has HttpClient
  • Angular 5 has new router Life-cycle Events
  • Angular 5 has improved faster Compiler support

Q.18 What is the difference between angular 2 and 4?

The differences between angular 2 and angular 4, are

  • Angular 2 was released in 2016 and Angular 4 in 2017
  • Angular 2 supports up to Typescript 1.8 and Angular 4 supports TypeScript 2.1 and 2.2 version
  • Angular 4 is next iteration of Angular 2 as Angular 3 was skipped.
  • Core concepts and inheritance is same in Angular 4 and Angular 2
  • Angular 4 has extensive changes in core library as compared to Angular 2
  • Angular 4 has reduced size of AOT compiler generated code
  • In Angular 4 animation is in @angular/animation
  • Angular 4 has, Else block in *ngIf introduced
Q.19 Is there any angular certification?

Yes, there are many certification exam for Angular

You should select certification for angular by answering following questions

  • Does Hard copy or e-learning is provided?
  • Practice test for assessing oneself is given?
  • Are video demonstrations provided?
  • What is the alumni strength

Vskills provides following deliverables for angular certification

  • Online video based, e-learning LMS
  • Hard copy to candidates residing in India
  • Practice tests for assessing your knowledge
  • Government certification
  • Vast alumni strength working in reputed software companies like Accenture, Cognizant, IBM, TCS, etc
Q.20 What are the prerequisites to learn angular 4?

The prerequisites to learn angular 4 is good knowledge of object oriented programming and Typescript. Both will help in quickly mastering Angular 4.

You can learn Angular 4 at link - https://www.vskills.in/certification/tutorial/web-development/angular-4-tutorials/

Q.21 What is angular training?

Angular training involves getting to know Angular open source Javascript framework and developing web applications and SPAs using Angular.

Angular training should also include assessment and certification of your skills and knowledge of Angular open source Javascript framework.

Vskills provides following deliverables for angular certification

  • Online video based, e-learning LMS
  • Hard copy to candidates residing in India
  • Practice tests for assessing your knowledge
  • Government certification
  • Vast alumni strength working in reputed software companies like Accenture, Cognizant, IBM, TCS, etc

Hence, Vskills Angular certification fulfills all requirements for certification on Angular and the link is -

https://www.vskills.in/certification/index.php?route=product/search&search=Angular

Links for tutorial on Angular, are

Angular 2  - https://www.vskills.in/certification/tutorial/web-development/angular-2-tutorials/

Angular 4 - https://www.vskills.in/certification/tutorial/web-development/angular-4-tutorials/


Q.22 What certification pays the most?

Certifications pays as per your skill and knowledge.

Vskills offers many certifications and students have got good paying jobs with Vskills certifications.

Professionals have also gained in getting increments in their jobs. Candidates working in MNCs, reputed corporate, across the globe have opted for Vskills certifications.

Q.23 Which online certification is best?

The best online certification is the one which you can clear easily.

Vskills offers best certifications with online e-learning, practice tests and Government certification.

Candidates working in MNCs, reputed corporate, across the globe have opted for Vskills certifications.

Q.24 What do you understand by 'Binding' and specify different types of binding in Angular 4?

Binding' in Angular 4 defines the process of establishing synchronization between the View and Model Components that are different layers in the application.

There are types of binding namely -

  • Data binding is the important and key factor in Angular components.
  • Two way binding is the combination of Event binding and Property binding features
  • Event binding is defined as the process of updating the values of a variable or attribute from View component layer to Model Component Layer
  • Property Binding is defined as the process of updating the of a variable or attribute in Model component and displaying the values in View component.
Q.25 Differentiate between Components and Directives in Angular 4?

In Angular 4, components are defined as the basic classes that interact with the web page components like html files or UI elements. Also the components is defined as Components using Decorators and every component will be designated with a predefined a template.

On the other hand a Class can be defined using an Angular Directive to make it a Directive that can be used at run time by processing and instantiating.

Q.26 In Angular 4, how would you define 'Typescript' and define it uses?

Typescript' is a defined general-purpose programming language that has been developed by Microsoft and also a superset of JavaScript programming language. The Angular 4 framework has been built on top of Typescript language.

Typescript is the key language used in Angular that is treated as a first-class citizen. We can use Typescript to develop Angular apps and the code will be transpiled thereafter using transpilers to support multiple or different versions of browser platforms.

Q.27 Define the various components in Angular 4.

This is one of the most common Angular 4 Interview Questions asked in an interview. We can define the components in Angular 4 are defined as the basic classes that interact with the web page components like html file. Also the components will be defined as Components using Decorators.

Some of the feature of component in Angular 4 are -
1. Each and every component will be designated with a predefined a template.
2. Components can be defined using @Component referred as Decorator.

Selector, style, and template can be defined inside the component to implement the further functionality.

Q.28 How do you define Modules in Angular 4?

We can define a Module in Angular 4 as the file such that all the directives, components, pipes and services are grouped and interlinked together in order to make it a perfect working Angular application.

Such that every Angular app has a root module that can be defined inside app.module.ts that is the Typescript file format. Now in order to define a module in Angular 4, NgModule can be used.

Q.29 How do you define routing in Angular 4?

In Angular application, Routing can be defined as the process of applying routes to different components to display the content of the component that are defined primarily in Single Page Applications. Such that this routing configuration can be defined in the root AppModule.

Here, the Router functionality in Angular enables the users to navigate from one task to different other tasks while performing multiple functionalities. Route is primarily defined as the application by mapping the URL to the different components.

Q.30 How do you define Directives in Angular 4?

We define 'Directives' in Angular 4 as the extended HTML attributes that has been defined as custom attributes. Directives in Angular 4 can be pre-defined or Custom defined to manipulate the functionality of DOM elements.

Different kinds of Directives in Angular 4 namely -

  • Components - Components are nothing but directives with a template.
  • Structural Directives - Structural Directive is defined as which changes the DOM structure by adding or removing the DOM elements.
  • Attribute Directives - Attribute Directives are defined as a modification in the behavior of a component, or an element or any other directive.
Q.31 How do you define isolated unit tests in Angular 4?

One of the most popular Angular 4 interview question, we can define Isolated Unit Test has been defined as the process of performing tests on a component or class in an isolated way rather than establishing any dependency with other components.

Isolated units refers to the testing that will be performed based on every individual components and element in isolation. Isolated Unit Tests are useful in testing the Angular Services and Pipes.

Q.32 How do describe Services in Angular 4?

In Angular 4, Services is defined as the process of using the code functionality of the other Components in one component. Applications such as data connections those need to be utilised across different components can be achieved by using the Services in Angular 4.

Such that the process of presenting the data from Model to View and vice versa is established by using Services.

Q.33 How do you define Dependency Injection (DI) in Angular 4?

In Angular 4, dependency Injection can be defined as the process of isolating the dependencies and tight coupling across different components. Dependency Injection holds the dependencies of components in other components. Also Angular-Dependency Injection is one of the way of creating the objects that depend on other objects.

Such that the instances of other components has to be created or injected into another component using Injection feature.

Q.34 What do you understand by ngIf directive?

ngIf is a built-in template directive that has been used to add or remove some parts of DOM. Such that this addition or removal depends on the expression being true or false.

Now if the expression is evaluated to false, then the ngIf directive removes the HTML element and if the expression is evaluated to be true, then the element gets added to the DOM.

Q.35 How is CLI command used to generate a component in Angular4?

We define components as simple classes which are declared as components with the help of component decorators. It becomes easy to create an application that already works, with the help of angular CLI commands.

The “Ng generate” is used to generate components, routes, services, and pipes. Also the simple test shells are also created with the help of this CLI command. In order to generate a component in angular4 with the help of CLI command, following the below syntax-

ng generate component component_name;


It generates the component and adds the component to module declarations.

Q.36 What is the component directory structure of angular4?
The elements that are present in the component directory structure modules are -
1. module.ts- The angular module is declared. @NgModule decorator is used which initializes the different aspects of angular applications. AppComponent is also declared in it.
2. components.ts - It defines the components in angular and this is the place where the app-root sector is also defined. Such that a title attribute is also declared in the component.
3. component.html - It is referred as the template file of the application which represents the visual parts of our components.
Q.37 What are component decorators in Angular4?
Decorator is the core concept while developing an angular framework with version 2 and above. This may come up as a core language feature for JavaScript soon. In angular 4, decorators are used extensively to compile a code. There are four different types of decorators -
1. Class decorators
2. Property decorators
3. Method decorators
Parameter decorators

We can define a decorator as a function which is invoked with a prefixed “@” symbol and is immediately followed by a class, parameter, method, or property. Such that a decorator returns the same thing which was given as an input but in an augmented form.
Q.38 How would you include an external css in Angular 4?
We can include external CSS in Angular 4, open your .angular-cli.json and then add your css file path in styles array.
Q.39 What are the breaking changes between angular 2 & angular 4?
Well, there is no path-breaking change that means Angular 4 is not an absolute rewrite of Angular 2. Google has adapted SEMVER approach for it’s Angular Framework. So due to misalignment of the router can exception. As @angular/router obtained using v3.3 already, so they switch to Angular 4.
Q.40 What are the new features of Angular 4?
The new features of Angular 4 are -
1. Revamped *ngIf and *ng For
2. Router ParamMap
3. TypeScript Compatibility
4. Animations Package
5. Dynamic Components
6. Angular Universal
7. Smaller and Quick
8. View Engine – AOT Compilation
9. Flat ES Modules (Flat ESM / FESM)
10. Source Maps for Templates
Q.41 What do you understand by Routing?
Basic building blocks of an Angular purpose are Ng Modules that use the router help in app, to convey the Router that this system knows what those involve and how they should work.
Q.42 How do you define Pipes angular 4?

A pipe takes in data as input and transforms it to a desired output. Such that every application starts out including everything appears like a simple task - get data, change them, and show them to users.

Getting data could be because easy as generating each local variable or as complex as streaming data over a WebSocket.

Q.43 How do you define Event Emitters in Angular 4?

Angular never guarantees that Event Emitter will continue doing an Observable. This means refactoring our policy if it turns.

This unique API must request its emit() method. We should nevermore support manually to an Event Emitter.

Q.44 How can we enable lazy loading in Angular 4?
We enable lazy loading in Angular 4 in the following way -
1. Configure the routes.
2. Set up an applying, in case you do not already have an app, you can regard the steps below to create one with the CLI.
3. Create a center module with a routing link. Next, you’ll need some following module to route to.
4. Add a part on the new module link.
5. Add another characteristic module link. Set up the link.
Q.45 How do you define dependency injection in angular?

Dependency Injection (DI) can be defined as a software object pattern which contracts with how elements make hold of their dependencies.

In which case AngularJS injector subsystem is in charge of building components, thereby choosing their dependencies, including providing them to other components as requested.

Q.46 Describe the use of @Input and @Output?
@Input is a decorator to mark an input field, @Input is used to determine an input property to achieve element property binding. On the other hand @Output is a decorator to identify an output property.
Q.47 Give the difference between Angular JS and Angular 4 app?
Angular 4 is complete rewrite of Angular JS. Such that Angular JS is based on controller based application and Angular 4 is component based application with Typescript .
Q.48 How do you define string interpolation?
String Interpolation is used to bind the value to HTML where the variable is defined inside component .
Q.49 What is the purpose of Router.navigate ()?
We primarily use router.navigate() to navigate to different component ( different pages ).
Q.50 How do you define widget?
The external module get components, directives and pipes from widget module.
Q.51 How do you define Lazyloading ?
Lazyloading permits to load component asynchronously when a specific route is activated.
Get Govt. Certified Take Test