If you are appearing for an AngularJS interview, then this article will provide the most frequently asked AngularJS interview questions with detailed answers to help you crack the job interview easily. Here we have listed the top AngularJS interview questions for freshers and experienced candidates that an interviewer might ask during the interview. 

In this blog, we have categorized the AngularJS interview questions under the following: 

Before we start with the interview questions on AngularJS, let’s take a look at the demand for AngularJS developers. 

Demand for AngularJS Developers

Web development has been a lucrative profession with the growth of the internet as well as businesses creating websites to make their presence known on the internet. High-skilled web developers are in huge demand as businesses not only want to develop websites but also maintain them. As an expert web developer, one should be proficient in many web application frameworks and tools, including AngularJS. 

AngularJS is a JavaScript open-source front-end web application framework that can be added to an HTML page with a <script> tag. It is one of the highly-sought skills that employers look for in a web developer. 

AngularJS has gained a lot of popularity lately due to its capability to cater to the multiple needs of front-end application development. According to Google Trends, AngularJS is more popular than Vue.js (another front-end JavaScript framework commonly used in the marketplace).

The demand for Angular JS developers is rapidly increasing due to the shortage of skilled resources in the marketplace. With an increase in the demand for AngularJS developers, the AngularJS developer salary is also increasing consistently. Due to its growing popularity, many developers are now eager to learn the AngularJS framework so that they can get benefits from their career perspectives.

If you are someone who has recently started your career in web development, then you can take up an online AngularJS course to acquire the required AngularJS skills.

Top AngularJS Interview Questions and Answers

Here is the list of top AngularJS interview questions and answers

Basic Level Angular Interview Questions

Q1. What is AngularJS?

Ans. AngularJS is a client-side JavaScript Model-View-Controller (MVC) framework used for developing rich and extensible web applications. It mainly runs on plain JavaScript and HTML and is suitable for Single Page Applications (SPA).

Q2. What are the different features of AngularJS?

Ans. The various features of AngularJS are:

  • Architecture
  • Codeless
  • Data Binding
  • Deep Linking
  • Dependency Injection
  • Directives
  • Not Browser Specific
  • Productivity
  • Routing
  • Speed and Performance

Q3. What are Directives in AngularJS?

Ans. AngularJS lets you extend HTML with new attributes called Directives. Thus, Directives in AngularJS are extended HTML attributes. Most of the directives in AngularJS come with the prefix ng-.  Some of the built-in Directives are:

  • ng-app – initializes AngularJS and makes the specified element a root element of the application
  • ng-init – initializes variables in AngularJS application
  • ng-bind – binds the model property declared via $scope or ng-model directive, or the result of an expression to the HTML element
  • ng-model – binds <input>, <select> or <textarea> elements to a specified property on the $scope object
  • ng-repeat – repeats HTML once per each item in the specified array collection
  • ng-app – it initializes an AngularJS application

Q4. What are Expressions in AngularJS?

Ans. Expressions in AnjularJS are used to bind application data to HTML. They are written inside double curly braces like {{expression}} and behave in the same way as ng-bind directives. They are pure JavaScript expressions and output the data where they are used. 

For example: <p>Name: {{name.title}}</p>

Q5. Explain $scope in Angular?

Ans. ‘$scope’ is a built-in object containing application data and methods. ‘$scope’ object instance gets created when ‘ng-controller’ directive is encountered. 

For example:

function Function1($scope)

$scope.ControllerName = “Function1”;

function Function2($scope)

$scope.ControllerName = “Function2”;

Q6. What should be the maximum number of concurrent “watches”?

Ans. There should be a maximum of 2000 to reduce memory consumption and improve performance.

Q7. Can we force the digest cycle to run manually?

Ans. Yes, we can force the digest cycle to run manually by using $apply().

Q8. Which is the latest version of angular?

Ans. Angular 8 is the latest version of angular.

Q9. What is Data Binding in AngularJS?

Ans. The automatic synchronization of data between the model and view components is referred to as Data Binding in AngularJS. AngularJS applications usually have a data model, a collection of data available for the application. The View is the HTML container where the AngularJS application is displayed.

Q10. What are the different types of Directives?

Ans. The different types of Directives are –

    • Components directives
  • Structural directives
  • Attribute directives 

Q11. Name different types of Linking Function.

Ans. The two types of Linking Functions are pre-linking function and post-linking functions.

Q12. What is the Controller in AngularJS?

Ans. A Controller is a set of JavaScript functions that are bound to a specified scope, the ng-Controller directive.

Also Read: Top 30 React Interview Questions and Answers

Q13. Is AngularJS compatible with all browsers?

Ans. Yes, it is compatible with all browsers, including Google Chrome, Mozilla Firefox, Safari, Opera, Internet Explorer, and Mobile browsers.

Q14. Name some major browsers supported by AngularJS?

Ans. The following are some of the major browsers supported by AngularJS:

  • Google Chrome
  • Mozilla Firefox
  • Microsft Edge
  • IE 10, 11, 
  • IE Mobile
  • Safari

Q15. Name the building blocks of the Angular.

Ans. Following are the building blocks of Angular:

  • Blocks
  • Lane
  • Template
  • Component
  • Services
  • Pro injection
  • Orders
  • Data Nemo

Intermediate Level Angular Interview Questions

Q16. What is a Digest Cycle in AngularJS? How does it work?

Ans. AngularJS Digest Cycle refers to the process of data binding. It observes the watchlist and keeps a track of changes in the value of the watch variable. In each digest cycle, Angular compares the previous and the new version of the scope model values. This process is triggered automatically but we can also trigger it manually by using $apply().

Q17. How can you decrease Digest Cycle Time?

Ans. When a digest cycle is triggered, it loops over every binding to detect model changes. The digest cycle time can be decreased by reducing the number of watchers. This also reduces application memory footprints.

Q18. How can you share data between Controllers?

Ans. There are two main scenarios while sharing data between Controllers:

  1. Sharing data between a parent and a child controller
  2. Sharing data between unrelated controllers

The sharing of data between a parent and a child controller can be done by: 

  • using $parent in HTML code
  • use of $parent in child controller
  • using controller inheritance

Sharing data between controllers without having relation – It can be done by:

  • Holding the shared data in a factory or service
  • Using the rootScope variable
  • Use of events to notify other controllers about changes to the data

Q19. What is the Currency Filter? What are the two ways to use Currency Filters?

Ans. The Currency Filter formats a number to a currency format. If no currency format is specified, then the currency filter uses the local currency format. 

Currency Filter Syntax:

{{currencyexpression | currency : symbol : fractionsize}}

Q20. What is Dependency Injection?

Ans. Dependency Injection is a process where we inject the dependent objects rather than the consumer creating the objects. It is a design pattern used to implement IoC. Dependency Injection is providing the objects that an object needs (its dependencies) instead of having it construct them itself. It involves 3 types of classes.

  • Client Class
  • Service Class
  • Injector Class

Q21. What are the benefits of Dependency Injection?

Ans. The following are the benefits of Dependency Injection:

  • It offers a client the flexibility of being configurable
  • It allows testing to be performed using mock objects
  • Loosely coupled architecture

Q22. What is the “$rootScope” in AngularJS?

Ans. Scope provides a separation between View and its Model. Every application has a $rootScope provided by AngularJS, and every other scope is its child scope. If a variable has the same name in both the current scope and in the rootScope, then the application uses the one in the current scope.

Q23. How to create a service in AngularJS?

Ans. In AngularJS, the service is created by registering it with the module in which it will operate. It can be created in three ways: 

  • Factory
  • Service
  • Provider

Q24. Mention the major differences between AngularJS and JavaScript Expressions.

Ans. Some of the significant differences between AngularJS and JavaScript Expressions are –

Angular Expressions JavaScript Expressions
1. AngularJS expressions  are evaluated against a scopeobject 1. They are evaluated against the global window
2. AngularJS expressions can be written in HTML 2. JavaScript expressions cannot be written in HTML
3. These expressions don’t support conditionals, loops, and exceptions 3. JavaScript expressions support conditionals, loops, and exceptions
4. AngularJS expressions support filters 4. They do not support filters
5. One time binding is supported 5. One time binding is not supported

 Q25. What is the SPA (Single page application) in AngularJS?

Ans. SPAs are web applications that load a single HTML page and dynamically update that page as the user interacts with the app.

Also Read: Top JavaScript Interview Questions and Answers

Q26. Which directive is used to hide elements from the HTML DOM by removing them from that DOM and not changing their styling?

Ans. ngIf Directive is used to hide elements from the HTML DOM by removing them from that DOM and not changing their styling

Q27. How do you disable a button depending on a checkbox’s state?

Ans. We can disable a button depending on a checkbox’s state by using the ng-disabled directive.

Q28. What is Representational State Transfer (REST) in AngularJS?

Ans. REST is a style of API that operates over HTTP requests. The requested URL identifies the data to be operated on, and the HTTP method identifies the operation that is to be performed.

Q29. When should you use an Attribute versus an Element?

Ans. An Attribute is used when we are decorating an existing element with new functionality.

An Element is used when we are creating a component that is in control of the template.

Q30. Name some commonly used inbuilt services in AngularJs.

Ans. There are 30 inbuilt services in AngularJs. Some of the commonly used services include: 

  • $location
  • $scope
  • $http
  • $window
  • $interval
  • $timeout

Q31. What is DDO (Directive Definition Object)?

Ans. DDO is an object used while creating a custom directive. It tells the compiler how a Directive needs to be assembled. Some of the properties include the link function, controller function, template, restrict, and templateUrl.

Q32. What is the Provider Method in AngularJS?

Ans. A provider is an object that creates a service object by allowing it to take more control. It is an object with a $get() method. The $get() method used in the provider returns the service object. The service name and the factory function are the arguments that are passed into the provider method. AngularJS uses $provide to register new providers.

Syntax:

 serviceApp.provider(“logService”, function ()) 

Q33. What are the attributes that can be used during the creation of a new AngularJS Directives?

Ans. Restrict, Template URL, Template, Replace, Transclude, Scope, Require, Controller, Link, and Compile are used during the creation of new AngularJS Directives.

Q34. What are the Angular Modules?

Ans. The Angular Modules collectively define an angular application that enables one to write angular codes. It is a mechanism to group components, directives, pipes, and interrelated services. Angular Modules create an application by combining it with other modules.

Q35. What are the directive scopes in AngularJs?

Ans. There are three directive scopes in AngularJs.

  • Parent scope – Any change made in the directive comes from the parent scope. It is also a default scope.
  • Child scope – This scope inherits a property from the parent scope.
  • Isolated scope – It is a reusable scope when a self-contained directive is built. It does not have any properties of the parent scope.

Q36. What is the Template?

Ans. Templates are the static HTML part of the Angular app and comprise of attributes and directives. They have an additional syntax that ensures customized user experience through a data injection process.

Q37. What is Internationalization?

Ans. Internationalization is used to create multilingual websites. It facilitates presenting locale-specific information on a website.

Q38. What is the String Interpolation?

Ans. String Interpolation is a service to evaluate angular expressions by matching the text and attributes to see if they have any embedded expressions.

Q39. What are AngularJS prefixes $ and $$?

Ans. These prefixes are used to avoid any accidental code collision with the user’s code.

$ prefix – Used with public objects

$$ prefix – Used with private objects

Q40. What is Strict Contextual Escaping?

Ans. Strict Contextual Escaping is a mode in which AngularJS constraints untrusted binding values. Here the AngularJS automatically runs security checks or shows an error if it cannot guarantee the security of the result.

Also Read: Top Python Interview Questions and Answers

Q41. What is the Factory Method?

Ans. Factory Method is a process of creating the directive, and it is invoked only when a compiler matches the directive for the first time. We can use $injector.invoke to invoke the factory method.

Q42. What is Deep Linking?

Ans. Deep Linking enables encoding the application state in any URL such that it can be bookmarked, and the application can be restored.

Q43. What is the role of $routeProvider in AngularJs?

Ans. $routeProvider helps to navigate between different pages or links without loading them separately. It is configured by using ngRoute config().

Q44. What is ng-switch?

Ans. In AngularJs, ng-switch conditionally exchanges the structure of the Document Object Model (DOM) on a scope-based expression template. In simpler words, it is used to show/hide the child elements on the HTML page.

Q45. What is the AngularJs Global API?

Ans. It is a set of global JavaScript functions such as protocols, routines, and tools for building software applications. Global API helps the users to perform tasks like compare and iterate objects, and convert data while interacting with the application.

Q46. Name some common API functions.

Ans. Some of the common API functions are –

  • angular. Lowercase – Converts a string to lowercase string
  • angular. Uppercase – Converts a string to uppercase string
  • angular. isString – Returns true if the reference is a string
  • angular. isNumber – Returns true if the reference is a number

Q47. What are events in AngularJS?

Ans. AngularJS Events are specific directives that can be used to customize the behavior of various DOM events like click, dblclick, mouseente. Some of the events supported by Angular are:

AngularJS Event Directives
ng-click
ng-blur
ng-click
ng-copy
ng-dblclick
ng-keydown
ng-keypress
ng-keyup
ng-mousedown
ng-mouseenter
ng-mouseleave
ng-mousemove
ng-mouseover
ng-mouseup

Q48. How will you validate a URL?

Ans. A URL can be validated by adding the regex directly to the ng pattern to the attribute.

 Q49. What is Event Handling?

Ans. Event Handling in AngularJs is used to create advance AngularJs applications. When you create more advanced AngularJS applications, your application will need to handle DOM events like mouse clicks, moves, keyboard presses, etc. AngularJS has a simple model for how to add event listeners to the HTML you generate from your views.

 Q50. Name a few tools for testing AngularJS applications.

  1. Karma
  2. Angular Mocks
  3. Browserify
  4. Mocha
  5. Sion

Q51. When do we use $location?

Ans. $location keeps track of the application URL and makes it available to a controller. $location can be used any time an application needs to react to a change in the existing URL or whenever we want to change the current URL in the browser.

Also Read: PHP Interview Questions and Answers

Q52. What is the role of Compile and Link in AngularJS?

Ans. Compile and Link perform the following functions: 

Compile – It traverses the HTML, finds for all the directives, and returns a link function.

Link – It combines the model with a view. In case of any change in the model, it is reflected in view, and in case of any change in view, it is reflected in the model.

Q53. Explain sessionStorage, cookies, and localStorage.

Ans. SessionStorage – It stores data for a particular session, and data will be lost when a browser tab is closed. Maximum storage is up to 5MB.

Cookies – It stores data that has to be sent back to the server or every HTTP request. We can set expiration from either the server-side or client-side, varying on the type and duration. Maximum storage is up to 4KB.

LocalStorage – It stores with no expiration date, and data can only be cleared by JavaScript or by clearing the browser cache. The storage limit is more than both sessionStorage and cookies.

Q54. Give an example to define a custom event.

Ans. Custom event can be defined using “objEvent = new EventEmitter()”

Q55. Which method of RouterModule provides all routes in AppModule?

Ans. RouterModule.forRoot is used for providing all routes in AppModule.

Q56. What type of data can be used with an async pipe?

Ans. Promise, Observable can be used with an async pipe.

Q57. What are the ways that components follow to communicate with each other?

Ans. There are three ways to communicate with components:

  • Passing a component to another component
  • When the value is passed by using parent component
  • Passing through service

Q58. What is the procedure to create two-way data binding in Angular?

Ans. Two-way data binding can be created by combining the input and output binding into a single notation using the ngModel directive.

For Example: <input [(ngModel)]=”name” >  {{name}}

Q59. Explain One-Way Binding and Two-Way Binding.

Ans. One-Way Binding implies that the scope variable in the HTML will be set to the first value its model is bound to.

Two-Way Binding implies that the scope variable will change its value every time its model is assigned to a different value.

Q60. What are the different Angular Life Cycle hooks?

Ans. Following are the Angular life cycle hooks:

  • ngAfterViewInit ()
  • ngOnInit ()
  • ngDoCheck ()
  • ngOnChanges ()
  • ngAfterViewChecked ()
  • ngOnDestroy ()
  • ngAfterContentInit ()
  • ngAfterContentChecked ()

Q61. What are the different ways to create a decorator in Angular?

Ans. Following are two ways to create a decorator in Angular:

  • Module.decorator
  • $ provide.decorator

Also Read: Best Software Development Tools and Frameworks to Learn

Q62. Name the different types of NgModules.

Ans. There are four types of NgModules:

  • Service block
  • Widget block
  • Features module
  • Replacement module
  • Shared volume

Q63. Mention the different types of built-in pipes.

Ans. Following are the different types of built-in pipes:

  • Titlecase
  • Uppercase
  • Lowercase
  • Percent
  • Slice
  • Currency
  • Date
  • Decimal
  • Json

Advanced Level Angular Interview Questions

Q64. What is the procedure to update or upgrade the Angular CLI version?

Ans. To upgrade the application, we need to enable the following commands

  • npm error cache clean or npm cache (npm> 5 if)
  • npm install -g @ angular / cli @ upgrade version
  • npm uninstall -g angular-cli

Q65. Explain the difference between RouterModule.forRoot() vs RouterModule.forChild()?

Ans. RouterModule.forRoot is known as a static method, and it is used to configure the modules.

RouterModule.forChild() is also a static method but it configures the routes of lazy-loaded modules.

Q66. What is the procedure to debug the router?

Ans. It can be initiated by passing a flag when it is added to the app routes.

Example:

@NgModule({

imports: [ RouterModule.forRoot(routes, { enableTracing: true }) ],

exports: [ RouterModule ]

})

export class AppRoutingModule {}

Q67. What is an ng-App directive?

Ans. ng-App directive appoints the root element of an AngularJs application by defining the AngularJs application. In an HTML document, any number of ng-App directives can be defined, but only one AngularJS application can be auto-bootstrapped, and the rest need to be done automatically.

For example:

<div ng-app=””>

<p>My first expression: {{127 + 162}} </p>

</div>

Q68. What is the procedure to implement multiple API calls that need to happen in order using rxjs?

Ans. Following is the procedure to implement a multiple API calls:

Method 1

this.http.get(‘/api/url’).subscribe(data => {

this.http.get(/api/url/data).subscribe(data11 => {

});

});

Method 2:

Using “MergeMap”

this.http.get(‘/api/url’).pipe(

mergeMap(character => this.http.get(character.naukrilearning))

);

 

We hope that these Angular interview questions will help you clear your job interview. All the best!

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