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Angular, Interview Questions

Angular is an app-design framework and development plate form for creating web applications, Angular is a leading technology in web development as well as we know angular has great demand in the market.

Q) What are new features in Angular 9?


  • An undecorated class migration schematic added to the core.
  • Numeric Values are accepted in the formControlName.
  • Selector-less directives have now been allowed as base classes in View Engine in the compiler.
  • Conversion of ngtsc diagnostics to ts.Diagnostics is possible

Q) What is the difference between $scope and scope in Angular?

Ans:-  $scope in Angular is used for implementing the concept of dependency injection (D.I) on the other hand scope is used for directive linking.
$scope is the service provided by $scopeProviderwhich can be injected into controllers, directives or other services whereas Scope can be anything such as a function parameter name, etc.

Q) What is the purpose of Wildcard route?

Ans:- Wildcard routing is used in Angular 8 for defining the route of pages. Specific changes/updates can be made when defining the route using Wildcard.

Q) How to detect a route change in Angular?

Ans:- To detect router change in Angular 8, the $on() method is used. This is an event handler used to handle $routeChangeSuccess when triggered by a route/view change or update.

Q) What is the difference between Angular 7 and Angular 8?


Angular 7 Angular 8
i) Angular 7 is difficult to use
ii) It has features such as Virtual scrolling, CLI prompts, Application performance, Drag, and drop, Bundle budget, Angular compiler, Angular elements, NativeScript, Better error handling, etc.
iii) Breaking changing in Angular 7 are- Component Dev Kit (CKD), Material design library and virtual scrolling.
iv) It will support a lower version of typescript version 3.4.
v) It supports all types Node.js version
i) Angular 8 is easier to use
ii) It has unique and advanced level features such as Differential Loading, Ivy rendering Engine, API builders, Bazel support, Support for $location, Router backward compatibility, Opt-In Usage sharing, web- workers, etc.
iii) Breaking changing in Angular 8 are- Core framework, Angular, material library and CLI.
iv) It will not support a lower version of typescript version 3.4.
v) It supports Node.js version 12 or later

Q) What is the difference between promise and observable in angular8?


Observables Promises
i) Both synchronous as well as asynchronous
ii) Can emit multiple values
iii) It is lazy
i) Always asynchronous
ii) Provides only one single value
iii) It is eager


Read Also: Laravel Interview Questions & Answers

Q) What is the difference between virtual Dom and real Dom?


Virtual DOM Real DOM
i) Is a collection of modules designed to provide a declarative way to represent the DOM for an application.
ii) A virtual DOM object is a representation of a DOM object, like a lightweight copy.
iii) Virtual DOM is ideal for mobile-first applications.
i) DOM is a language-neutral interface allowing programs and scripts to dynamically access and update multiple objects like content, structure, and style of a document
ii) The DOM represents the document as nodes and objects.
iii) It is an object-oriented representation of a web page, modified with a scripting language like JavaScript.

Q) How to install Angular 8?

Ans:- Steps for the Installation of Angular 8 environmental setup

Step 1)  Before installing Angular, first you need to install the Node.js in your system install it using the following steps.
The basic requirement of Angular 8 is Node.js version 110.9.0 or later.

  • Download it using https//nodejs.org/en/
  • Install it on your system
  • Open node.js command prompt
  • Check the version run command, node-v in the console window

Step 2) In order to install Angular CLI, use the following commands

Step 3) Check the installed node and angular version using below command, run the command in terminal

Q) What is a service in Angular?

Ans:- Services allow for greater separation of concerns for your application and better modularity by allowing you to extract common functionality out of components. A service is used when a common functionality needs to be provided to various modules. Let’s create a repoService which can be used across components,

Q) How to pass headers for HTTP client?

Ans:- You can directly pass object map for http client or create HttpHeaders class to supply the headers.

Q) What is the purpose of common module?

Ans:- Common module is used to export all basics Angular directives and pipes, such as NgIf , NgForOf , DecimalPipe , and so on. Directives provided by @angular/common module. Apart from these HttpClientModule is available under @angular/common/http.

Q) What are pipes in angular?

Ans:- A pipe is a class decorated with pipe metadata. A pipe takes in data as input and transforms it to a desired output. For example, let us take a pipe to transform a component’s birthday property into a human-friendly date using date pipe.

Q) What is TypeScript?

Ans:- TypeScript is an open-source programming language developed and maintained by Microsoft. TypeScript is a typed superset of JavaScript and has optional types, classes, async/await, and many other features, and compiles to plain JavaScript. Angular built entirely in TypeScript and used as a primary language. You can install it globally using below command.

Q) What is Angular Router?

Ans:- Angular Router is a mechanism in which enables to show different components and data to the user based navigation happens from one view to the next as users perform application tasks. It borrows the concepts or model of browser’s application navigation.

Read Also: Top Interview Questions & Answers on Angular

Q) What is JIT?

Ans:- JIT stands for Just-in-Time, Angular offers two ways to compile your application.
Just-in-Time (JIT) is a type of compilation that compiles your app in the browser at runtime. JIT compilation is the default when you run the ng build (build only) or ng serve (build and serve locally) CLI commands. i.e, the below commands used for JIT compilation.

Q) What are the router imports?

Ans:- Angular router is an optinal service and it is not a core part of Angular. The Angular Router which represents a particular component view for a given URL is not part of Angular Core. It is available in library named @angular/router to import required router components. For example, we import them in app module as below.


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