45+Top Angular 7 Interview Questions & Answers [ SOLVED ]

Last updated on 04th Jul 2020, Blog, Interview Questions

These Angular 7 Interview Questions have been designed specially to get you acquainted with the nature of questions you may encounter during your interview for the subject of Angular 7 . As per my experience good interviewers hardly plan to ask any particular question during your interview, normally questions start with some basic concept of the subject and later they continue based on further discussion and what you answer.we are going to cover top 100 Angular 7 Interview questions along with their detailed answers. We will be covering Angular 7 scenario based interview questions, Angular 7 interview questions for freshers as well as Angular 7 interview questions and answers for experienced.

Q1. What is Angular 7? How is it different from AngularJS?

Ans:

• Angular7 is the latest and recent version of Angular. AngularJS was the first version of Angular which is also known as Angular 1.0.
• Angular7 is the complete rewrite of Angular1.0. It supports two-way data binding, and some other features like ng update, ng add, Angular Elements, Angular Material + CDK Components, Angular Material Starter Components, CLI Workspaces, Library Support, Tree Shakable Providers, Animations Performance Improvements, and RxJS v6 etc.

Q2. What is Angular framework?

Ans:

Angular is a TypeScript-based open-source web framework and a platform. It is used to build web/ mobile and desktop applications.

Q3. What are the Main features of the Angular 7 framework ?

Ans:

• Declarative templates
• dependency injection
• end to end tooling

Q4. What is the difference between AngularJS and Angular?

Ans:

Angular is a complete rewrite of AngularJS. It is a component-based framework in which an application is a tree of individual components.

AngularJS	Angular
AngularJS is based on MVC architecture.	Angular is based on Service/Controller.
It uses JavaScript to build the application.	It uses TypeScript to build the application.
It follows the controller concept.	It follows Component based UI approach.
It is not a mobile-friendly framework.	It is a mobile friendly framework.
It is very difficult to create a SEO friendly application in AngularJS.	By using Angular, you can easily create a SEO friendly application.

Q5. What is the difference between structural directive and attribute directive in Angular 7?

Ans:

• Structural directives are used to alter the DOM layout by removing and adding DOM elements. These directives are far better in changing the structure of the view. Examples of Structural directives are NgFor and Nglf.
• Attribute Directives are used as characteristics of elements. For example, a directive such as built-in NgStyle in the template Syntax guide is an attribute directive.

Q6. What is the difference among “declarations”, “providers” and “import” in NgModule?

Ans:

Difference among declarations”, “providers” and “import” in NgModule:

• declarations are used to make directives (including components and pipes) from the current module available to other directives in the current module. Selectors of directives, components or pipes are only matched against the HTML if they are declared or imported.
• providers are used to make services and values known to DI. They are added to the root scope and they are injected to other services or directives that have them as dependency. A special case for providers is lazy loaded modules that get their own child injector. Providers of a lazy loaded module are only provided to this lazy loaded module by default (not the whole application as it is with other modules).
• import makes the exported declarations of other modules available in the current module.

Q7. What are the key components of Angular?

Ans:

Key components of Angular:

• Components: Components are the basic building blocks of angular application and used to control HTML views.
• Modules: Modules are the set of angular basic building blocks like components, directives, services etc. An application is divided into logical pieces and each piece of code is called a “module” and used to perform a single task.
• Templates: Templates are used to represent the views of an Angular application.
• Services: It is used to create components which can be shared across the entire application.
• Metadata: This can be used to add more data to an Angular class.

Q8. Explain the Architecture overview of Angular?

Ans:

Angular is the most popular web development framework for developing mobile and web applications. It uses cross platform mobile development called IONIC that’s why it is not limited to web apps only.

There are 7 main building blocks of an Angular application:

• Component
• Templates
• Metadata
• Data Binding
• Directives
• Services
• Dependency Injection

The basic building blocks of an Angular application are NgModules, which provide a compilation context for components. Angular app is defined by a set of NgModules and it always has at least a root module that enables bootstrapping, and many more feature modules.

• Components define Template views
• Components use services

The NgModules make developers organize an application into connected blocks of functionality.

The NgModule properties for the minimum “AppModule” generated by the CLI are as follows:

• Declarations: Use to declare the application components.
• Imports: Every application must import a BrowserModule to run the app in a browser.
• Providers: There is none to start.
• Bootstrap: This is a root AppComponent that Angular creates and inserts into the index.html host web page.

Q9. How would you update Angular 6 to Angular 7?

Ans:

You can update Angular 6 to Angular 7 by using the following command:
1. ng update @angular/cli @angular/core

Q10. What is the UrlSegment Interface in Angular 7?

Ans:

In Angular 7, the UrlSegment interface represents a single URL segment, constructor, properties and methods like this:

The UrlSegment is a part of a URL between the two slashes and it contains a path and matrix parameters associated with the segment.

Q11. What is Do Bootstrap (ng Do Bootstrap) In Angular 7?

Ans:

The ng Do Bootstrap is a new life-cycle hook added in Angular 7 and Do Bootstrap is an interface.
Question: What is Angular?
Answer: Angular is a TypeScript-based open-source web application framework, developed and maintained by Google. It offers an easy and powerful way of building front end web-based applications.
Angular integrates a range of features like declarative templates, dependency injection, end-to-end tooling, etc. that facilitates web application development.

Q12. Define the ng-content Directive?

Ans:

Conventional HTML elements have some content between the tags. For instance:

Now consider the following example of having custom text between angular tags:

However, doing so won’t work the way it worked for HTML elements. In order to make it work just like the HTML example mentioned above, we need to use the ng-content Directive. Moreover, it is helpful in building reusable components.

Q13. Please explain the various features of Angular?

Ans:

There are several features of Angular that makes it an ideal front end JavaScript framework. Most important of them are described as follows:

• Accessibility Applications: Angular allows creating accessible applications using ARIA-enabled components, built-in a11y test infrastructure, and developer guides.
• Angular CLI: Angular provides support for command-line interface tools. These tools can be used for adding components, testing, instant deploying, etc.
• Animation Support: Angular’s intuitive API allows the creation of high-performance, complex animation timelines with very little code.
• Cross-Platform App Development: Angular can be used for building an efficient and powerful desktop, native, and progressive web apps. Angular provides support for building native mobile applications using Cordova, Ionic, or NativeScript. Angular allows creating high performance, offline, and zero-step installation progressive web apps using modern web platform capabilities. The popular JS framework can also be used for building desktop apps for Linux, macOS, and Windows.
• Code Generation: Angular is able to convert templates into highly-optimized code for modern JavaScript virtual machines.
• Code Splitting: With the new Component Router, Angular apps load quickly. The Component Router offers automatic code-splitting so that only the code required to render the view that is requested by a user is loaded.
• Synergy with Popular Code Editors and IDEs: Angular offers code completion, instant errors, etc. with popular source code editors and IDEs.
• Templates: Allows creating UI views with a simple and powerful template syntax.
• Testing: Angular lets you carry out frequent unit tests using Karma. The Protractor allows running faster scenario tests in a stable way.

Q14. Demonstrate navigating between different routes in an Angular application?

Ans:

Following code demonstrates how to navigate between different routes in an Angular app dubbed “Some Search App”:

Q15. Could you explain services in Angular?

Ans:

• Singleton objects in Angular that get instantiated only once during the lifetime of an application are called services. An Angular service contains methods that maintain the data throughout the life of an application.
• The primary intent of an Angular service is to organize as well as share business logic, models, or data and functions with various components of an Angular application.
• The functions offered by an Angular service can be invoked from any Angular component, such as a controller or directive.

Q16. Enumerate some salient features of Angular 7?

Ans:

Unlike the previous versions of Angular, the 7th major release comes with splitting in @angular/core. This is done in order to reduce the size of the same. Typically, not each and every module is required by an Angular developer. Therefore, in Angular 7 each split of the @angular/core will have no more than 418 modules.

Q17. What is string interpolation in Angular?

Ans:

Also referred to as moustache syntax, string interpolation in Angular refers to a special type of syntax that makes use of template expressions in order to display the component data. These template expressions are enclosed within double curly braces i.e. {{ }}.
The JavaScript expressions that are to be executed by Angular are added within the curly braces and the corresponding output is embedded into the HTML code. Typically, these expressions are updated and registered like watches as a part of the digest cycle.

Q18. Explain Angular Authentication and Authorization.

Ans:

The user login credentials are passed to an authenticate API, which is present on the server. Post server-side validation of the credentials, a JWT (JSON Web Token) is returned. The JWT has information or attributes regarding the current user. The user is then identified with the given JWT. This is called authentication.

Q19. Can you explain the concept of scope hierarchy in Angular?

Ans:

Angular organizes the $scope objects into a hierarchy that is typically used by views. This is known as the scope hierarchy in Angular. It has a root scope that can further contain one or several scopes called child scopes.

Q20. What are directives in Angular7?

Ans:

In Angular7, directives are used to add behavior to an existing DOM element or an existing component instance.
For Example

Q21. When was Angular 7 released?

Ans:

on October 18, 2018

Q22.Angular 7 is developed by?

Ans:

Google

Q23.What’s new in Angular 7?

Ans:

Angular Elements is enabled to support content projection with the help of web standards for custom elements.

• Angular Material Gets Minor Updates: Angular Material got better in the display that gives it an elegant look in the new update. Moreover, it also added a new homepage for the material, material.io. In this, you get tooling, design guidance, development components and stay up-to-date with the latest news. If you are using an Angular Material v7 then you observe a visual difference as the library makes changes to itself with the updated version of the Material Design.
• Better Accessibility for Selects: In the updated version, it includes a lot of new features to enhance accessibility for selects. It adds a new feature of the native select inside mat-form-field. It is far better and outperformed than the mat- select. Both the select and mat-select are available so you can choose what you want to do.
• Virtual Scrolling: The Component Dev Kit (CDK) is available in the market with the great virtual scrolling capabilities that the user can apply by importing the `ScrollingModule`!

• Drag & Drop: The CDK in the new update also now recommends Drag & Drop, which possess these great hallmarks:
• Automated render as a user moves items
• It is new feature available only in Angular 7
• Helper methods for reordering/transferring items in lists: For reordering or transferring items in lists, you can use a helper method: moveItemInArray and transferArrayItem
• Enhancing Application Performance: You will get enhanced application performance in Angular 7
• A safeguard has come into play for the users of Angular 7

It gives a portent to new application builders when they are crossing the budget with their bundle size. The warning occurs on 2 MB whereas an error occurs over 5 MB. But you don’t need to frighten. You can change the limits simply in your angular.json file.

Q24.What is IVY Renderer? Is it supported by Angular 7?

Ans:

Angular will be releasing a new kind of rendering pipeline and view engine.
The purpose of angular view engine is to translate the templates and components that we have written into the regular HTML and JavaScript so it is easy for the browser to read it comfortably. Ivy is believed to be splendid for the Angular Renderer.
Yes, it is supported by Angular 7.

Q25. What are the Core Dependencies of Angular 7?

Ans:

There are two types of core dependencies: RxJS and TypeScript.

• RxJS 6.3: RxJS version 6.3 is used by Angular 7. It has no changes in the version from Angular 6
• TypeScript 3.1: TypeScript version 3.1 is used by Angular 7. It is the upgrade from the version2.9 of Angular 6.

Q26.How to update Angular 4,5, 6 to Angular 7?

Ans:

• First of all, you need to update the Angular version globally by inserting the latest version via the terminal: sudo npm install -g @angular/cli@latest.
• The next step is to upgrade the version locally in your project and need to assure the altering for the new version are displayed in the package.json file ng update @angular/cli
• When it is done, upgrade all your dependencies and dev dependencies in package.json
• To build Angular applications, Angular-devkit was introduced in Angular 6 that needs the dependency on the CLI projects.
• With all of this, you’ll also require to upgrade the version for Typescriptnpm install typescript@2.9.2 –save-dev
• Then, you need to relocate the configuration of angular-cli.json to angular.json ng update @angular/cli and ng update @angular/core.
• Use this command: ng update @angular/material in case of Angular material is used.
• The next step is the removal of deprecated RxJS 6 features npm install -g rxjs-tslint rxjs-5-to-6-migrate -p src/tsconfig.app.json
• When it is done, uninstall rxjs-compat as it is not required for Angular npm uninstall –save rxjs-compat
• Also change import { Observable } from ‘rxjs/Observable’; to import { Observable } from ‘rxjs’;
• Finally, you are able to start your Angular 7 application by using ng serve

Q27.Explain Bazel use in Angular 7?

Ans:

Bazel is a test tool just like the Make, Maven and Gradle and it is an open-source build. Bazel utilizes readable and high-level build language. It handles the project in a great number of languages and builds the product for a large number of platforms. Moreover, it supports multiple users and large codebases over several repositories.

Q28.How to generate a class in Angular 7 using CLI?

Ans:

Create a class in ANgular 7 using below code:

Where name refers to the name of a class.

Q29.How can you create a decorator in Angular?

Ans:

There are two ways to register decorators in Angular. These are:

• $provide.decorator, and
• module.decorator

Q30. How can you handle events in Angular 7?

Ans:

There are various methods to handle events in Angular 7. These are:

• Binding to user input events: You are able to use the Angular event binding to answer DOM events. User input triggers so many DOM events. It is a very effective method to get input from the user.
• Get user input from the event object: DOM carries a cargo of the information that possibly is valuable for the components.
• Key event filtering: Every keystroke is heard by the (keyup) event handler. The enter keys matter the most as it provides the sign of the user that he has done with the typing. The most efficient method of eliminating the noise is to look after every $event.keyCode and the action is taken only when the enter key is pressed.

Q31.What is the difference between Structural and Attribute directives in Angular?

Ans:

• Structural directives: These are used to alter the DOM layout by removing and adding DOM elements. It is far better in changing the structure of the view. Examples of Structural directives are NgFor and Nglf.
• Attribute Directives: These are being used as characteristics of elements. For example, a directive such as built-in NgStyle in the template Syntax guide is an attribute directive.

Q32. What is TestBed in Angular?

Ans:

Angular Test Bed (ATB) is the primary API for writing unit tests for Angular Application and libraries. It allows us to test behaviors and change detections that depend on the Angular Framework.

Q33. What Is Angular Compatibility Compiler (ngcc) In Angular 7?

Ans:

The ngcc Angular node_module compatibility compiler :

• The ngcc is a tool which “upgrades” node_module compiled with non-ivy ngc into ivy compliant format.
• This compiler will convert node_modules compiled with Angular Compatibility Compiler (ngcc), into node_modules which appear to have been compiled with TSC compiler transformer (ngtsc) and this compiler conversions will allow such “legacy” packages to be used by the Ivy rendering engine.
• TSC transformer which removes and converts @Pipe, @Component, @Directive and @NgModule to the corresponding definePipe, defineComponent, defineDirective and defineInjector.

Q34. What Is Do Bootstrap (ng Do Bootstrap ) In Angular 7?

Ans:

Do Bootstrap Interface :
Angular 7 added a new life-cycle hook that is called ng Do Bootstrap and an interface that is called Do Bootstrap.
Example:

Q35. What Is Xmb?

Ans:

The XMB is basically a key value pair with no deeper structure. It does have a mechanism for named placeholders, with descriptions and examples. The messages for any given other language must correspond 1:1.

Q36. What Are Xmb Placeholders?

Ans:

The placeholders have one example tag () and a text node. The text node will be used as the original value from the placeholder, while the example will represent a dummy value.

Q37. What Is Ivy Rendering Engine In Angular 7?

Ans:

Ivy Rendering Engine: The Ivy rendering engine is a new backwards-compatible Angular renderer mainly focused on the following.

• Speed Improvements
• Size Reduction
• Increased Flexibility

The template functions for creating dynamically views are no longer nested functions inside each other.

Q38. What Is the Key Value Pipe In Angular 7?

Ans:

Key Value Pipe: Change your object into an array of key value pairs that output array will be ordered by keys. By default it will be by Unicode point value.

Syntax:

Q39. Explain Bazel?

Ans:

Bazel is a test tool just like the Make, Maven and Gradle and it is an open-source build. Bazel utilizes the readable and high-level build language. It handles the project in a great number of languages and builds the product for a large number of platforms. Moreover, it supports multiple users and large codebases over several repositories.

Q40. What is Decorator in Angular7?

Ans:

Decorators are a new feature of TypeScript and used throughout the Angular code, but they are nothing to be scared of. With decorators we can configure and customise our classes at design time. They are just functions that can be used to add meta-data, properties or functions to the thing they are attached to.

Q41. What are components in Angular7?

Ans:

Components are the basic building blocks of an Angular app formed like a tree structure. Components are a subset of directives but unlike directives, components always have a template and only one component can be instantiated per an element in a template.

Q42. What is the difference between component and directive?

Ans:

Component	Directive
If you register a component, you have to use @Component meta-data annotation	If you register a directive, you have to use @Directive meta-data annotation
Components are used to break up the application into smaller components.	Directives are used to design reusable components.
Components are used to create UI widgets.	Directives are used to add behavior to an existing DOM element.
Only one component can be present per DOM element.	Many directives can be used per DOM element.
@View decorator or templateurl/template are mandatory	Directives don’t use View.

Q43. What is a template in Angular7?

Ans:

A template is a HTML view where you display your data by binding controls to Angular component’s properties. You can store your component’s template in one of two places. You can define it inline using the template property, or you can define the template in a separate HTML file and link to it in the component metadata using the @Component decorator’s templateUrl property.

Q44. What is a module?

Ans:

Modules are the logical boundaries in the application. An application is divided into separate modules to separate the functionalities of the application.

Q45. What are the new features added in Angular7?

Ans:

Following is a list of new features added in Angular7:

• Angular7 displays an elegant look in the new update.
• It provides virtual scrolling by using the scrolling package .
• It facilitates you to use drag and drop property by using the @angular/cdk/drag-drop module.
• In Angular7, libraries make changes to themselves automatically with the updated version of the Material design.
• Angular7 provides better error handling for @Output if property is not initialized.
• Angular7 provides added support for Node v10.

Q46. Explain what is the difference between Angular and backbone.js?

Ans:

Following are the various notable differences between Angular and Backbone.js

• Architecture: Backbone.js makes use of the MVP architecture and doesn’t offer any data binding process. Angular, on the contrary, works on the MVC architecture and makes use of two-way data binding for driving application activity.
• Community Support: Being backed by Google greatly ups the community support received by the Angular framework. Also, extensive documentation is available. Although Backbone.js has a good level of community support, it only documents on Underscore.js templates, not much else.
• Data Binding: Angular uses a two-way data binding process and thus is a bit complex. Backbone.js, on the contrary, doesn’t have any data binding process and thus, has a simplistic API.
• DOM: The prime focus of Angular JS is upon valid HTML and dynamic elements that imitate the underlying data for rebuilding the DOM as per the specified rules and then works on the updated data records. Backbone.js follows the direct DOM manipulation approach for representing data and application architecture changes.
• Performance: Thanks to its two-way data binding functionality, Angular offers an impactful performance for both small and large projects. Backbone.js has a significant upper hand in performance over Angular in small data sets or small webpages. However, it is not recommended for larger webpages or large data sets due to the absence of any data binding process.
• Templating: Angular supports templating via dynamic HTML attributes. These are added to the document to develop an easy to understand application at a functional level. Unlike Angular, Backbone.js uses Underscore.js templates that aren’t fully-featured as Angular templates.
• The Approach to Testing: The approach to testing varies greatly between Angular and Backbone.js due to the fact that while the former is preferred for building large applications the latter is ideal for developing smaller webpages or applications. For Angular, unit testing is preferred and the testing process is smoother through the framework. In the case of Backbone.js, the absence of a data binding process allows for a swift testing experience for a single page and small applications.
• Type: Angular is an open-source JS-based front-end web application framework that extends HTML with new attributes. On the other hand, Backbone.js is a lightweight JavaScript library featuring a RESTful JSON interface and MVP framework.

Q47. How do Observables differ from Promises?

Ans:

As soon as a promise is made, the execution takes place. However, this is not the case with observables because they are lazy. This means that nothing happens until a subscription is made. While promises handle a single event, observable is a stream that allows passing of more than one event. A callback is made for each event in an observable.

Q48. Please explain the difference between Angular and AngularJS?

Ans:

Various differences between Angular and AngularJS are stated as follows:

• Architecture – AngularJS supports the MVC design model. Angular relies on components and directives instead
• Dependency Injection (DI) – Angular supports a hierarchical Dependency Injection with unidirectional tree-based change detection. AngularJS doesn’t support DI
• Expression Syntax – In AngularJS, a specific ng directive is required for the image or property and an event. Angular, on the other hand, use () and [] for blinding an event and accomplishing property binding, respectively
• Mobile Support – AngularJS doesn’t have mobile support while Angular does have
• Recommended Language – While JavaScript is the recommended language for AngularJS, TypeScript is the recommended language for Angular
• Routing – For routing, AngularJS uses $routeprovider.when() whereas Angular uses @RouteConfig{(…)}
• Speed – The development effort and time are reduced significantly thanks to support for two-way data binding in AngularJS. Nonetheless, Angular is faster thanks to upgraded features
• Structure – With a simplified structure, Angular makes the development and maintenance of large applications easier. Comparatively, AngularJS has a less manageable structure
• Support – No official support or updates are available for AngularJS. On the contrary, Angular has active support with updates rolling out every now and then

Q49. Observe the following image:

What should replace the “?”?

Ans:

Directives. The image represents the types of directives in Angular; Attribute, structural, and custom.

Q50. Could you explain the concept of templates in Angular?

Ans:

Written with HTML, templates in Angular contain Angular-specific attributes and elements. Combined with information coming from the controller and model, templates are then further rendered to cater the user with the dynamic view.

Q51. Explain the difference between an Annotation and a Decorator in Angular?

Ans:

• In Angular, annotations are used for creating an annotation array. They are the only metadata set of the class using the Reflect Metadata library.
• Decorators in Angular are design patterns used for separating decoration or modification of some class without changing the original source code.

Q52. What are directives in Angular?

Ans:

Directives are one of the core features of Angular. They allow an Angular developer to write new, application-specific HTML syntax. In actual, directives are functions that are executed by the Angular compiler when the same finds them in the DOM. Directives are of three types:

• Attribute Directives
• Component Directives
• Structural Directives

Q53. What are the building blocks of Angular?

Ans:

There are essentially 9 building blocks of an Angular application. These are:

• Components – A component controls one or more views. Each view is some specific section of the screen. Every Angular application has at least one component, known as the root component. It is bootstrapped inside the main module, known as the root module. A component contains application logic defined inside a class. This class is responsible for interacting with the view via an API of properties and methods.
• Data Binding – The mechanism by which parts of a template coordinate with parts of a component is known as data binding. In order to let Angular know how to connect both sides (template and its component), the binding markup is added to the template HTML.
• Dependency Injection (DI) – Angular makes use of DI to provide required dependencies to new components. Typically, dependencies required by a component are services. A component’s constructor parameters tell Angular about the services that a component requires. So, a dependency injection offers a way to supply fully-formed dependencies required by a new instance of a class.
• Directives – The templates used by Angular are dynamic in nature. Directives are responsible for instructing Angular about how to transform the DOM when rendering a template. Actually, components are directives with a template. Other types of directives are attribute and structural directives.
• Metadata – In order to let Angular know how to process a class, metadata is attached to the class. For doing so, decorators are used.
• Modules – Also known as NgModules, a module is an organized block of code with a specific set of capabilities. It has a specific application domain or a workflow. Like components, any Angular application has at least one module. This is known as the root module. Typically, an Angular application has several modules.
• Routing – An Angular router is responsible for interpreting a browser URL as an instruction to navigate to a client-generated view. The router is bound to links on a page to tell Angular to navigate the application view when a user clicks on it.
• Services – A very broad category, a service can be anything ranging from a value and function to a feature that is required by an Angular app. Technically, a service is a class with a well-defined purpose.
• Template – Each component’s view is associated with its companion template. A template in Angular is a form of HTML tags that lets Angular know how it is meant to render the component.

Q54. Please explain the differences between Angular and jQuery?

Ans:

The single biggest difference between Angular and jQuery is that while the former is a JS frontend framework, the latter is a JS library. Despite this, there are some similarities between the two, such as both features DOM manipulation and provides support for animation.

Nonetheless, notable differences between Angular and jQuery are:

• Angular has two-way data binding, jQuery does not
• Angular provides support for RESTful API while jQuery doesn’t
• jQuery doesn’t offer deep linking routing though Angular supports it
• There is no form validation in jQuery whereas it is present in Angular

Q55. Could you explain the difference between Angular expressions and JavaScript expressions?

Ans:

Although both Angular expressions and JavaScript expressions can contain literals, operators, and variables, there are some notable dissimilarities between the two. Important differences between Angular expressions and JavaScript expressions are enlisted below:

• Angular expressions support filters while JavaScript expressions do not
• It is possible to write Angular expressions inside the HTML tags. JavaScript expressions, contrarily, can’t be written inside the HTML tags
• While JavaScript expressions support conditionals, exceptions, and loops, Angular expressions don’t

Q56.What is subscribing and multicasting in Angular?

Ans:

When someone subscribes then at that point in time the observable instance helps in the development of the values.On the other hand, the process of broadcasting the list of several multiple subscribers and that too in a single execution this process is known as multicasting. The observable used here then here you have no registered listeners on the document. So what happens here is that by the use of the first listener we can send the values to each and every subscriber and that also we can keep reusing it.

Q57. What is the difference between pure and impure pipe in Angular?

Ans:

The difference between pure and impure pipes are:

Pure pipes	Impure pipes
Here it only executes a pure pipe only when there is a change in the internal state of the pipe.	Here the execution of the impure pipe is done on every change in the component during the entire cycle.
The change here can be primitive or non-primitive.	Here if you want to be a pipe to be impure then at that time you need to change the settings from flag to false.

Q58. Enlist the type of forms supported by Angular 7?

Ans:

There are two types of Forms available in Angular 7.

• Reactive Forms: It uses an explicit and immutable approach to managing the state of a form at a given point in time.
• Template-driven Forms: All logics, validations, controls are written in the template part.

Q59. What is Angular Material?

Ans:

It is a UI component library. Angular Material helps in creating attractive, consistent, and fully functional web pages as well as web applications. It does so while following modern web design principles, including browser portability and graceful degradation.

Q60. What is AOT (Ahead-Of-Time) Compilation?

Ans:

Each Angular app gets compiled internally. The Angular compiler takes in the JS code, compiles it and then produces some JS code. This happens only once per occasion per user. It is known as AOT (Ahead-Of-Time) compilation.

Q61. What are the utility functions provided by RxJS?

Ans:

The utility functions provided by Angular are:

• map() : Used to map values of different data types
• filter() : Used for filtering streams
• concat() : Used to concatenate multiple strings
• merge(): Used to recursively descend into object properties in the source copy, while forming a deep copy of the same.

Q62. What does a router.navigate do?

Ans:

The Router.navigate is used to specify a root URL through relative navigation. Here’s a function using the above to navigate through different articles in Angular:

Q63. What are the router events?

Ans:

In Angular, during each navigation route, the Router sends navigation events through the Router Events property.

Here is the list of events ranging from when the navigation starts and ends too many points in between.

• NavigationStart
• RouteConfigLoadEnd
• GuardsCheckStart
• ActivationStart
• GuardsCheckEnd
• ResolveStart
• ActivationEnd
• NavigationEnd

Q64. What are the features of using the AoT compiler?

Ans:

Here are the reasons to use an AOT compiler in Angular:

• Faster rendering: Using the AOT compiler, browsers can download a pre-compiled version of the application. This ensures that the browser can render the application immediately using executable code without having to wait for the whole compilation.
• Less asynchronous requests: Using inline external HTML templates and CSS style sheets within the application, the compiler eliminates separate ajax requests for those specific resource files.
• Reduced Angular framework download size: There’s no need to download the Angular compiler if the app is already compiled. This is very advantageous and efficient as the compiler is almost half the size of Angular, so, not having to add that increases the application payload dramatically.
• Optimized Error Handling: Detecting existing template errors and reporting template binding errors during the building step before users can see.
• Enhanced Security: Compilation of HTML templates and other components into JS files before client-side rendering. This reduces the scope for risky JS evaluation or injection attacks. The AOT compiles the HTML templates and other components into JS files before they are served to the client. With no templates to read and no risky client-side JavaScript or HTML evaluation, there are fewer opportunities for injection attacks.

Q65. What are angular global APIs?

Ans:

An API stands for Application Programming Interface. It is basically a set of rules and tools for building software applications. In AngularJS, the Global API is a combination of global functions written in Javascript which are used for tasks like comparing/iterating objects or converting data.

Q66. List the difference between structural directive and attribute directive in Angular 7?

Ans:

• Structural directive: The main function of the structural directive is to shape and re-shape the HTML layout, and DOM’s structure. The modification and customization of HTML layout are done by adding, removing and manipulating the selected HTML elements.
• Attribute directives: The attribute directive has its own layout view and styles because it has a single component on a host element but it supports multiple directives.

Q67. What is Data Binding? How many ways can it be done?

Ans:

In order to connect application data with the DOM (Data Object Model), data binding is used. It happens between the template (HTML) and component (TypeScript). There are 3 ways to achieve data binding:

• Event Binding – Enables the application to respond to user input in the target environment
• Property Binding – Enables interpolation of values computed from application data into the HTML
• Two-way Binding – Changes made in the application state gets automatically reflected in the view and vice-versa. The ngModel directive is used for achieving this type of data binding.

Q68. What is demonstrated by the arrow in the following image?

Ans:

This represents a dependency injection or DI.

Q69. Can you draw a comparison between the service() and the factory() functions?

Ans:

• Used for the business layer of the application, the service() function operates as a constructor function. The function is invoked at runtime using the new keyword.
• Although the factory() function works in pretty much the same way as the service() function does, the former is more flexible and powerful. In actuality, the factory() functions are design patterns that help in creating objects.

Q70. Please explain the digest cycle in Angular?

Ans:

• The process of monitoring the watchlist in order to track changes in the value of the watch variable is termed the digest cycle in Angular. The previous and present versions of the scope model values are compared in each digest cycle.
• Although the digest cycle process gets triggered implicitly, it is possible to start it manually by using the $apply() function.

Q71. List the Core Dependencies of Angular 7?

Ans:

Angular 7 has two core dependencies namely RxJS and TypeScript

• RxJS 6.3 – Angular 7 framework uses RxJS version 6.3.
• TypeScript- Angular 7 framework uses TypeScript version 3.1

Q72. How to set headers for every request in Angular?

Ans:

In order to set headers for every request in Angular 7, HTMLHttpRequest is used. There are a number of benefits such as testability features, types request, request and response interception, observable APIs and streamlined error handling that is associated with XMLHttpRequest.

Q73. Could you explain the various types of filters in AngularJS?

Ans:

In order to format the value of expression so that it can be displayed to the user, AngularJS has filters. It is possible to add these filters to the controllers, directives, services, or templates. AngularJS also provides support for creating custom filters.

Organizing data in such a way so that it is displayed only when certain criteria are fulfilled is made possible using filters. Filters are added to the expressions using the pipe ‘|’ character. Various types of AngularJS filters are enumerated as follows:

• currency – Formats a number to the currency format
• date – Formats a data to some specific format
• filter – Selects a subset of items from an array
• json – Formats an object to a JSON string
• limitTo – Limits an array or string into a specified number of characters or elements
• lowercase – Formats a string to lowercase
• number – Formats a number to a string
• orderBy – Orders an array by an expression

Q74. What is new in Angular 6?

Ans:

Here are some of the new aspects introduced in Angular 6:

• Angular Elements – It allows converting Angular components into web components and embeds the same in some non-Angular application
• Tree Shakeable Provider – Angular 6 introduces a new way of registering a provider directly inside the @Injectable() decorator. It is achieved by using the providedIn attribute
• RxJS 6 – Angular 6 makes use of RxJS 6 internally
• i18n (internationalization) – Without having to build the application once per locale, any Angular application can have “runtime i18n”

Q75. What is SPA (Single Page Application) in Angular? Contrast SPA technology with traditional web technology?

Ans:

In the SPA technology, only a single page, which is index.HTML, is maintained although the URL keeps on changing. Unlike traditional web technology, SPA technology is faster and easy to develop as well.

Q76. What is the process called by which TypeScript code is converted into JavaScript code?

Ans:

It is called Transpiling. Even though TypeScript is used for writing code in Angular applications, it gets internally transpiled into equivalent JavaScript.

Q77. What is ViewEncapsulation and how many ways are there to do it in Angular?

Ans:

To put simply, ViewEncapsulation determines whether the styles defined in a particular component will affect the entire application or not. Angular supports 3 types of ViewEncapsulation:

• Emulated – Styles used in other HTML spread to the component
• Native – Styles used in other HTML doesn’t spread to the component
• None – Styles defined in a component are visible to all components of the application

Q78. Why prioritize TypeScript over JavaScript in Angular?

Ans:

TypeScript is a superset of Javascript as it is Javascript + Types or extra features like typecasting for variables, annotations, variable scope and much more. The typescript is designed in a way to overcome Javascript shortcomings like typecasting of variables, classes, decorators, variable scope and many more. Moreover, Typescript is purely object-oriented programming that offers a “Compiler” that can convert to Javascript-equivalent code. 

Q79. Discuss the life cycle designed for directive and components in Angular JS especially for the newly introduced version 6.0?

Ans:

Components and directive of AngularJS follow the following typical lifecycle.

• nhOnInit
• ngDoCheck
• ngOnDestroy
• Constructor
• ngOnChanges
• ngAfterContentInit (only for components)
• ngAfterContentChecked (only for components)
• ngAfterViewInit (only for components)
• ngAfterViewChecked (only for components)

Q80. Why was Angular introduced as a client-side framework?

Ans:

Traditionally, VanillaJS and jQuery were used by developers to develop dynamic websites. As the websites became more complex with added features and functionality, it was hard for the developers to maintain the code. Moreover, there was no provision of data handling facilities across the views by jQuery. So, Angular was built to address these issues, thus, making it easier for the developers by dividing code into smaller bits of information that are known as Components in Angular. Client-side frameworks permit the development of advanced web applications like SPAs which, if developed by VanillaJS, is a slower process.

Q81. What are Lifecycle hooks in Angular? Explain some life cycles hooks?

Ans:

Angular components enter its lifecycle from the time it is created to the time it is destroyed. Angular hooks provide ways to tap into these phases and trigger changes at specific phases in a lifecycle.

• ngOnChanges(): This method is called whenever one or more input properties of the component changes. The hook receives a SimpleChanges object containing the previous and current values of the property.
• ngOnInit(): This hook gets called once, after the ngOnChanges hook. It initializes the component and sets the input properties of the component.
• ngDoCheck(): It gets called after ngOnChanges and ngOnInit and is used to detect and act on changes that cannot be detected by Angular. We can implement our change detection algorithm in this hook.
• ngAfterContentInit(): It gets called after the first ngDoCheck hook. This hook responds after the content gets projected inside the component.
• ngAfterContentChecked(): It gets called after ngAfterContentInit and every subsequent ngDoCheck. It responds after the projected content is checked.
• ngAfterViewInit(): It responds after a component’s view, or a child component’s view is initialized.
• ngAfterViewChecked(): It gets called after ngAfterViewInit, and it responds after the component’s view, or the child component’s view is checked.
• ngOnDestroy(): It gets called just before Angular destroys the component. This hook can be used to clean up the code and detach event handlers.

Q82. Could we make an angular application to render on the server-side?

Ans:

Yes, we can, with Angular Universal, a technology provided by Angular capable of rendering applications on the server-side. The benefits of using Angular Universal are:

• Better User Experience: Allows users to see the view of the application instantly.
• Better SEO: Universal ensures that the content is available on every search engine leading to better SEO.
• Loads Faster: Render pages are available to the browsers sooner, so the server-side application loads faster.

Q83. Explain Dependency Injection?

Ans:

Dependency injection is an application design pattern that is implemented by Angular and forms the core concepts of Angular. Let us understand in a detailed manner. Dependencies in Angular are services which have a functionality. Various components and directives in an application can need these functionalities of the service. Angular provides a smooth mechanism by which these dependencies are injected into components and directives.

Q84. Describe the MVVM architecture?

Ans:

MVVM architecture removes tight coupling between each component. The MVVM architecture comprises of three parts:

• Model
• View
• ViewModel

The architecture allows the children to have reference through observables and not directly to their parents.

• Model: It represents the data and the business logic of an application, or we may say it contains the structure of an entity. It consists of the business logic – local and remote data source, model classes, repository.
• View: View is a visual layer of the application, and so consists of the UI Code(in Angular- HTML template of a component.). It sends the user action to the ViewModel but does not get the response back directly. It has to subscribe to the observables which ViewModel exposes to it to get the response.
• ViewModel: It is an abstract layer of the application and acts as a bridge between the View and Model(business logic). It does not have any clue which View has to use it as it does not have a direct reference to the View. View and ViewModel are connected with data-binding so, any change in the View the ViewModel takes note and changes the data inside the Model. It interacts with the Model and exposes the observable that can be observed by the View.

Q85. Do these questions show relevancy to Angular 6 Interview Questions?

Ans:

Yes, they can be considered as Angular 6 Interview Questions.

Q86.What is angular and why angular?

Ans:

• Angular is an open source Javascript framework, to develop software applications for the internet especially dynamic web applications. Angular is used to develop single page applications or SPA.
• The main advantage of using Angular being, ease of development as it uses HTML like syntax to declare various functionality of a web application.
• Why Angular, because Angular makes it easy to quickly develop application  for both web and mobile. Angular hides the crude implementation and many things are provided, as

Angular offers

• Component-based architecture offering Reusability, Maintainability
• TypeScript giving better tooling, cleaner code, and higher scalability
• RxJS for efficient, asynchronous programming
• Hierarchical dependency injection
• Ivy renderer
• Angular Material for streamlining Material Design interface engineering
• Seamless updates using Angular CLI
• Angular elements

Q87.What is AOT in angular?

Ans:

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 a JIT compiler which ran after the application was bootstrapped in the web browser. AOT did code analysis, generated code in memory.
• With AOT, Angular apps reduced the requirement for change detection, or dependency injection during runtime.

Q88.Does Google use angular?

Ans:

As per Google – Angular is used in public-facing applications and sites such as Google Cloud Platform and AdWords, as well as many internal tools.Google also maintains Angular.

Q89.Is Angular JS MVC?

Ans:

Yes, AngularJS MVC uses MVC architecture

MVC in AngularJS divides an application into three interconnected parts of

• Model – It manages the data, logic and rules of the application.
• View – is output representation of information, such as a chart or a diagram. Multiple views of the same information are possible.
• Controller – accepts input and converts it to commands for the model or view.

Interaction of MVC in AngularJS, is as

• Model receives user input from the controller.
• View is the presentation of the model in a particular format.
• Controller receives the input, optionally validates it and then passes the input to the model.

Q90.Is there any certification for angular?

Ans:

Yes, there are many certification providers 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

Q91.What is angular training?

Ans:

• 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.

Q92.What is Google Certification Program?

Ans:

Google Certification Program is a platform by Google to showcase your skill and proficiency in various Google technologies like Android and Google cloud.

Q93.What is angular material design?

Ans:

Angular material design is

• a design language for web and mobile apps
• Angular material design was developed by Google in 2014.
• Angular material design is an adaptable system of guidelines, components, and tools that support the best practices of user interface design.
• Angular material design makes it easy for developers to customize their UI while still keeping a good-looking app interface that users are comfortable with.
• Angular material design initial focus was touch-based mobile apps, now it extends to web design.
• Angular material design defines the qualities that can be expressed by UI regions, surfaces, and components.

Q94.How will you create a decorator in Angular?

Ans:

Primarily there are two ways to register decorators in Angular. Such that –

• $provide.decorator
• module.decorator

Q95.What do you understand about IVY Renderer and Is it supported by Angular 7?

Ans:

Angular releases a new kind of rendering pipeline and view engine, given that the purpose of angular view engine is to translate the templates and components that we have written into the regular HTML and JavaScript so it is easy for the browser to read it comfortably.Ivy is believed to be splendid for the Angular Renderer. It is supported by Angular 7.

Q96.What do you understand by TestBed?

Ans:

• Angular Test Bed (ATB) is a higher level Angular Only testing framework that allows us to easily test behaviours that depend on the Angular Framework.
• We still write our tests in Jasmine and run using Karma but we now have a slightly easier way to create components, handle injection, test asynchronous behaviour and interact with our application. The TestBed creates a dynamically-constructed Angular test module that emulates an Angular

Q97.What do you understand by Redux and how is it related to an Angular app?

Ans:

Redux refers to a way to manage application state and improve maintainability of asynchronicity in the application by providing a single source of truth for the application state, and a unidirectional flow of data change in the application.

Q98.What do you understand about the Angular Console?

Ans:

• Angular CLI is defined as a powerful tool to develop an Angular application without following complex stuff. Angular Console is a way to achieve different command line features using a simple GUI which is completely alternative to know all of the CLI commands.
• In order to download the GUI tool, you can get the executable file from here. And after downloading the tool, it will look like this.

Q99.What is the Template Expression?

Ans:

Template expressions are the same expression that we use with JavaScript. But the difference is that we can use it within our Html template, so it looks like that we are using JavaScript along with Html but keep in mind that not every JavaScript expression is supported like (new), (++) and (–).

Q100. What‘s the basic syntax of a Decorator in Angular?

Ans: 

@() with optional parameters.