Top 20 AngularJS Interview Questions & Answers

  • By Manisha Jadhav
  • November 25, 2019
  • Angular
Top 20 AngularJS Interview Questions & Answers

AngularJS Interview Questions & Answers

Hello readers this blog is related to some of the most popular interview questions and answers that mostly asked in angularJs interview to read in depth regarding AngularJs read my previous blog  click here

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 1)   What is AngularJS?

Angular is a scripting language, which is used for building single-page applications. It works on the principle of “Javascript” framework, because its supports client-side scripting and Server-side scripting.

AngularJS is a javascript structure used for creating single web page applications (SPA).  It allows you to use HTML as your front-end language and enables you to extend HTML’s syntax to communicate your application’s components plainly.

Angularjs Tricky Interview

From the above diagram we can understand how is works on Real-time.It Runs on the concept of MVC model.which defines the behavior of data,logic and view layer.It is used for building web applications as well as Mobile applications.

2)  Explain key features of AngularJS ?

Below are the key features of AngularJS :

  • Template – which is used for Displaying data to user.
  • Scope – which is used for managing data(i.e.,updating,viewing,deletion).
  • Controller-which is used for connecting both Template and Scope.
  • Data binding-Its works on the principle of Newton’s 3rd law (for every action there is an equal reaction),because when data changes in template ,the scope effects the changes and vice versa.
  • Services-which is used to send data from one one controller to another.
  • Filters-To format data before displaying it you can use filters.(example:currency conversion).
  • Directives-which holds a set of instructions for the HTML It defines the specific behavior of DOM element.

3) Explain what is scope in AngularJS ?

Scope points to the application model, it acts like a stick between application view and the controller.  Scopes are set in hierarchical structure and impersonate the DOM ( Document Object Model) structure of the application.  It can watch expressions and propagate events.

4) what is services in AngularJS ?

In AngularJS services are the single functions or objects that are used for moving out specific tasks.  It holds some logical data and these data represented using a function  called as directive, controllers, filters and so on.

5)  What is Angular Expression? Explain key difference between angular expressions and JavaScript expressions?

Below points explains Difference between the and Angular expressions and JavaScript expressions

  • Forgiving: In Angular expression evaluation is forgiving to null and undefined, while in Javascript undefined properties generates ReferenceError or TypeError
  • No Control Flow Statements: Exceptions, Loops  or conditionals cannot be used in an angular expression
  • Filters: Basically filters used  to format data before displaying it on the browser

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6)  Explain what are directives? State some of the mainly used directives in AngularJS application?

Directive in angular is a function that the angular compiler executes whenever it finds it in DOM (Document Object Model). It basically adds functionality to the applications. It is the most used angular unit.  The directives can have a name either from the predefined Angular component (for example ng – repeat) or a custom name.

Few most used directives in Angular JS are – ng-model, ng-bind, ng-repeat, ng-hide, ng-init etc.

7)   State what are the advantages of using AngularJS?

Advantages of using angular JS are –

  • The mvc framework- mvc framework stands for model view controller. It ensures that the application development process is easy and eliminates the redundant code. This in turn promises less coding, lighter and faster apps.
  • Angular uses HTML interface as user interface language. Since html is a much easier language and deployed to build the front end part of the application.
  • It supports unit testing model. Each unit or component can be automatically, individually tested and the entire testing process is simple.
  • User friendly code- Angular has access to the POJO model i.e. plain old javascript object. It has planned logic and objects which helps in developing interactive, and user friendly applications.

8) Explain what AngularJS routes does?

In the process of developing Single page application (SPA), where we can navigate to different pages of the application without reloading the page, routing concept in angular js is deployed. AngularJS routes does the routing part of the application. The inclusion of Angular js route module namely ngRoute, routes the application to different pages without reloading the entire application.

9)  Explain what is data binding in AngularJS?

Data binding in angular js means the automatic synchronization of data between the model and view components of the application.  When the data in the model of the application changes, the change is reflected in the view and vice versa. The two ways for data binding are – data binding in classical template systems and data binding in angular templates.

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10) What makes AngularJS better?

The few points which makes angular js better are –

  • HTML user interface – the front end part of the interface is built using HTML with shorter tags and easy readability.
  • The MVC framework –while building any application the developer writes the logics differently and then combines the module using code. The MVC architecture helps the developers to build the client side applications. Angular JS using the MVC framework, which helps in easy building of the code.
  • Lesser code line – AngularJS needs less lines of code for any application. The front end part is developed using HTML tags. The application code and the directives to be used have different codes so can be written simultaneously.
  • Unit wise testing – AngularJS has made the testing process easier and simpler. The dependencies of the controllers uses the concept of dependency injection (which binds the entire application together) where the behavior and output of the controller can be found individually. Hence the name Unit testing.
  • Developed by Google – AngularJS is developed and maintained by Google and a dedicated group of people to assist any user to support any framework related issues.

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11) Explain what is string interpolation in AngularJS?

In the process of compilation the Angular JS compiler matches the text nodes and attributes values using the interpolation services to check for the embedded expressions. 

12)What is the difference between $scope and scope? 

The $scope is a built-in object in angular js, which contains application data and methods.

The $scope is in between a controller and view (HTML). It can transfers data from the controller to view and from view to controller vice-versa.

In short, in case of dependency injection the scope object is received as $scope while in case of non-dependency injection scope object is received as scope or with any name.

13) How are AngularJs prefixes $ and $$ used?

Angular Prefixes $ is used for names of public objects and $$ used for names of private objects.

It is used to prevent accidental name collisions with your code.

14) Where can we implement the DOM manipulation in AngularJs?

To manipulate the DOM we have directives in Angular JS like ng-show, ng-hide etc. Essentially an order is utilized to create the dynamic substance i.e., HTML at run time.

It does not exist in services, controllers or anywhere else.

15) How can we show that a scope variable should have one-time binding only?

One-time binding, “::” is used to show the scope variable.

The syntax will be like this :

<p>Hello {{::name}}!</p>

16)What is SPA (Single page application) in AngularJs?

 Single page application (SPA) is a web application that fits on a single page. All your code (JS, HTML, CSS) is recovered with a solitary page load. Also, route between pages performed without reviving the entire page.

No page refresh

At the point when you are utilizing SPA, you don’t have to invigorate the entire page, simply load the piece of the page which should be changed.

Precise enables you to pre-load and store every one of your pages, so you needn’t bother with additional solicitations to download them.

Better user experience

Single page application SPA feel like a native application: fast and responsive.

Ability to work offline

Regardless of whether client loses web association, SPA can even now work since every one of the pages are as of now stacked.

16) What are the binding directives in AngularJs?

The ng-bind directive tells AngularJS to replace the content of an HTML element with the value of a given variable, or expression. In the event that the estimation of the given variable, or articulation, changes, the substance of the predetermined HTML component will be changed too.

The binding directives include:          

  • ng-bind
  • ng-bind-html
  • ng-bind-template
  • ng-non-bindable
  • ng-model

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17)  Mention what are the characteristics of “Scope”?

  • Scopes give APIs ($watch) to watch model transformations.
  • Scopes give APIs ($apply) to reproduce any model changes through the framework into the view from outside of the “AngularJS domain” (controllers, services, AngularJS event handlers).
  • Scopes can be settled to restrict access to the application components parts while giving access to shared model properties. Settled extensions are either “kid scopes” or “isolate scopes”. A “youngster scope” (prototypically) acquires properties from its parent scope. A “seclude scope” doesn’t.
  • Scopes give setting against which expressions are assessed. For instance expressions are good for nothing, except if it is assessed against a particular extension which characterizes the username property.

 

18)  What is DI (Dependency Injection) and how an object or function can get a hold of its dependencies?

Reliance in writing computer programs is a methodology where a class utilizes explicit functionalities of another class. In this way, for instance, If you consider two classes A and B, and state that class An utilizations functionalities then you should realize that, you need to make an example of class B before the items are being utilized of class B, at that point its inferred that class A has a reliance of class B. Presently, in the event that you are coding in Java by class A.

The way toward making an item for some different class and let the class straightforwardly utilizing the reliance is called Dependency Injection. It essentially has three classes included:

  • Client Class: This is the needy class and is reliant on the Service class.
  • Service Class: This class gives a support of the customer class.
  • Injector Class: This class is liable for infusing the administration class object into the customer class

These are the manners in which that article uses to hold of its conditions

  • Typically utilizing the new administrator, reliance can be made
  • By alluding to a worldwide variable, reliance can be gazed upward

18)  what are the advantages of using Angular.js  framework?

Advantages of using Angular.js as framework are

  • Two way data-binding
  • MVC pattern
  • static template and angular template
  • Can add custom directive
  • REST full services
  • form validations
  • Support client and server communication
  • Support dependency injection
  • Support Animations
  • Event Handlers

19)  Explain the concept of scope hierarchy?  How many scopes can an application have?

Each angular application comprise of one root scope yet may have a few kid scopes. As kid controllers and a few orders make new youngster scopes, application can have different extensions. At the point when new extensions are framed or made they are included as an offspring of their parent scope. Like DOM, they likewise makes a progressive structure.

When AngularJS assesses , it first takes a gander at the degree related with the given component for the name property. In the event that no such property is discovered, it looks through the parent scope, etc until the root degree is come to. In JavaScript this conduct is known as prototypical legacy, and kid scopes prototypically acquire from their folks.

20)  What is the difference between AngularJS and backbone.js?

AngularJS joins the functionalities of the vast majority of the outsider libraries, it underpins singular functionalities required to create HTML5 Apps. While Backbone.js carry out their responsibilities independently.

AngularJS (Pros and Cons):

Angularjs Pros And Cons

Backbone.js (Pros and Cons):

Backbone Js Pros And Cons

Author: Manisha Jadhav | SevenMentor Pvt Ltd

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