What are AngularJs technical interview questions

48 Top AngularJS Interview Questions and Answers [2021 LIST]

48 top angularjs interview questions

List of the most frequently asked questions about the AngularJS interview with detailed answers for freshmen and seasoned professionals:

AngularJS is one of the most up-to-date web development frameworks in the world.

In almost every interview, you have to face stiff competition to get high and get your dream job. Therefore, you should prepare well in advance.

To help you along this journey, we've compiled a list of the most frequently asked questions about AngularJS interviews along with the answers your interviewer expects at the time of the interview.

Read our Series of AngularJS tutorials for more knowledge of the concept. Protractor for testing AngularJSApps was explained in our previous tutorial.

Most frequently asked questions about the AngularJS interview

Below is a list of the top AngularJS interview questions and answers so that anyone can complete an interview successfully.

Let's explore !!

Q # 1) What do you mean by AngularJS?

Reply: AngularJS is a JavaScript framework used to create rich and extensible web applications.

It runs on plain JavaScript and HTML, so you don't need any additional dependencies to make it work. AngularJS is perfect for single page applications (SPA). It is mainly used for binding JavaScript objects with HTML UI elements.

F # 2) Define the functions of AngularJS.

Answer: The functions include:

  • The template (view)
  • The scope (model)
  • The controller (controller)
  • Services
  • filter
  • Guidelines

F # 3) Define the data binding.

Reply: Data binding is an automatic reconciliation of data between the view and the model components.

F # 4) Distinguish between AngularJS and JavaScript expressions.

Answer: There are several differences between AngularJS and JavaScript expressions:

  • We can write AngularJS expressions in HTML, but we cannot write JavaScript expressions in HTML.
  • We can't use conditional iterations, loops, and exceptions in AngularJS, but we can use all of these conditional properties in JavaScript expressions.
  • Filters are supported in AngularJS, while filters are not supported in JavaScript.

F # 5) Write down all the steps to configure a n Angular App (In-App).

Answer: To set up an Angular app, you need to do the following:

  • angular.module is created first.
  • A controller is assigned to the module.
  • The module is linked to the HTML template (i.e. user interface or view) via an angle app (ng app).
  • The HTML template is linked to the controller (i.e. JS) via an ng-controller directive.

Q # 6) What are the angle modules?

Reply: The angle modules together define an angle application in which we can write the angle code. Modules contain the different parts of an angle application. A module is created by the function angle.module in angle.

Q # 7) What are the policy areas in AngularJS?

Reply: There are three policy areas available in AngularJS.

You are:

  • Parent area: Regardless of what changes you make to your directive that come from the parent section, this is also reflected in the parent section and is also a default section.
  • Sub-area: It is a nested area that inherits a property from the parent area. If properties and functions of the scope are not linked to the parent scope statement, a new child scope statement is created.
  • Isolated scope: It's reusable and will be used when we create a self-contained directive. It is only used for private and internal use, that is, it does not contain any properties of the parent realm.

Q # 8) How can we share the data between controllers in AngularJS?

Reply: First we need to create a service. The service is used to exchange the data between controllers in AngularJS in a very clear, simple and fastest way. We'll use events, $ parent, next sibling, and the controller using a $ rootScope.

Q # 9) What is the digestive cycle in AngularJs?

Reply: It's part of the process of data binding in AngularJS. It compares the old and the new version of the range model value in each digest cycle.

The digest cycle is triggered automatically. We can also improve the usability by using $ apply () if we want to manually trigger the digest cycle.

F # 10) Explain the differences between one-way binding and two-way binding.

Reply: One-way binding is used to bind the data from the model to the view without automatically updating the HTML template or view.

Therefore, to update the HTML template, we need to write custom code that updates the view every time data is bound from model to view.

While bidirectional binding is used to bind the data from the model to the view and vice versa (i.e. view to the model), the HTML template is automatically updated without writing custom code.

F # 11) Difference between sessionStorage, cookies and localStorage.

Answer: The differences are as follows:

  • SessionStorage - The data is saved for a specific session. The data is lost when the browser tab is closed or after a certain session. The maximum saved size can be up to 5 MB.
  • Local memory - The data is saved without an expiration date. The data can only be deleted using JavaScript or by deleting the browser cache. The maximum storage limit is SessionStorage and Cookie.
  • Cookies - It stores the data that needs to be sent back to the server with some requests. The expiry of the cookie depends on the type and duration, which have been set either on the server side or on the client side. The maximum saved size can be less than 4 KB.

Q # 12) What role does $ routeProvider play in AngularJS?

Reply: It's the $ routeProvider that helps navigate between different pages / links without loading the page / link separately when a user clicks on a link.

The routeProvider is configured with the ngRoute config () method.

Q # 13) What is the difference between $ scope and scope?

Reply: In AngularJS, $ scope is used to achieve dependency injection and scope is used to link between View (i.e. HTML) and Controller (i.e. JS).

Q # 14) How are AngularJS prefixes $ and $$ used?

Reply: The $$ variable in AngularJS is used as a private variable to prevent accidental code collision with user code.

The $ prefix can be used to denote angular kernel functionalities (such as a variable, parameter, property, or method).

Q # 15) Where can we implement DOM manipulation in AngularJS?

Reply: The manipulation of DOM takes place in directives and should not otherwise be present in the services of the controller or anywhere else.

Q # 16) How can we show that a range variable should only have a one-time binding?

Reply: To show a unique bond, we have to " :: :: In front of the rifle scope.

Q # 17) What is SPA (Single Page Application) in AngularJS?

Reply: It's a web application that loads a single HTML page and dynamically updates the page when the user connects to the app.

Using AJAX and HTML, SPA can create a fluid and responsive web app without reloading pages. This way we can create a responsive user interface with no page flicker.

Q # 18) How many types of data bindings are there in AngularJS?

Reply: AngularJS supports both one-way and two-way binding.

If we bind the data model in one way, there isn't a dynamic change that you see in the view, but in some way there is a dynamic change when a change is made in the data model.

Q # 19) What are the mandatory statements in AngularJs?

Answer: The mandatory guidelines include:

  • ng-bind
  • ng-bind-html
  • ng-bind-template
  • of not bindable
  • ng model

F # 20) Explain the ng-bind and ng-bind-html instructions.


ng-bind : It is a directive that replaces the content of the HTML element with the value of the assigned variable or expression.

The content of the HTML element changes by changing the value of the variable or expression.

It's like ({{expression}}) and the syntax for it is:

ng-bind-html : It is a directive that securely binds the content to the HTML element (view). The $ sanitize service is used to sanitize the content to be included in an HTML element. To do this, 'angle-sanitize.js' must be included in our application.

Syntax to write this

F # 21) Explain ng-bind-template and ng-non-bindable.


ng-bind-template : Replaces the text content of the element by interpolating the template. It can contain multiple double-curly markups.

Not bindable : AngularJS indicates that the content of this HTML element and its child nodes should not be compiled.

F # 22) Explain the ng-model directive in AngularJs.

Reply: This can be a jump to the application data using the HTML custom input form controls (such as input, text area, and selection). It provides form validation behavior with two-way binding.

F # 23) Define the factory method in AngularJS.

Reply: It's pretty similar to the service. Factories implement a module pattern in which we use a factory method to generate an object that is used to build models.

In a factory, a method object is returned at the end by creating a new object and adding functions as properties.

syntax ::

Q # 24) What is the ng-repeat directive in AngularJS?

Reply: It renders or iterates a collection of elements and creates DOM elements. It regularly monitors the data source to re-render a template in response to a change.


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Q # 25) What is a controller in AngularJS?

Reply: A controller is a JavaScript function that is bound to the specified area. Angular instantiates the new controller object and inserts the new area as a dependency.

A controller can be used to establish the initial state of the scope object and add behavior to the object. A controller cannot be used to share code or status between controllers. The Angular service can be used instead.

Q # 26) What are filters in AngularJS?

Reply: The main job of filters is to modify the data so that it can be merged into an expression or directive using a pipe character (used to apply filters in an angle symbol of a pipe that is (|), or this is the symbol).

A filter formats the value of an expression for display to the user. They can be used in view templates, controllers or services, and we can easily create our own filter as well. A filter is a module provided by AngularJS. There are nine components of a filter that it provides.

Examples:Currency, date, filter, JSON, limitTo etc.

Q # 27) What is the ng app directive in AngularJS?

Reply: It is used to define the AngularJs application. It sets the root element of the application and is stored near the tag or.

We can define any number of ng-app statements in the HTML document, but only one AngularJS application can be automatically booted (automatically booted) and the other applications have to be booted manually.


Q # 28) What is ng-switch in AngularJS?

Reply: It is used to conditionally swap the structure of DOM in a template that is based on a scope-based expression.

With this instruction you can show or hide the HTML element depending on the expression.

Q # 29) What is a double click event used for in AngularJs?

Reply: Here you can define the user-defined behavior in the event of a double-click of the mouse on a website. We can use it (ng-dblclick) as the attribute of the HTML element, such as

Q # 30) What are ng-include and ng-click directives in AngularJs?


ng-include helps to include various files on the main page. The ng-include directive contains HTML from an external file.

The content it contains is included as a child of the specified item. The value of the ng-include attribute can also be an expression that returns a file name.

By default, the contained file must be in the same domain as the document.

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ng-click can be used in scenarios such as: For example, when you click a button or when you want to perform an operation. It tells AngularJS what to do when an HTML element is clicked.


The above code increases the count variable by one when the button is clicked.

Q # 31) What is a REST (Representational State Transfer) in AngularJs?

Reply: REST is a style of API that is performed over the HTTP request.

The requested URL identifies the data to be worked with and the HTTP method identifies the operation to be performed. REST is more of an API style than a formal specification, and there is much debate and disagreement about what is RESTful and what is not. This term refers to an API that follows the REST style.

AngularJS is flexible in how RESTful web services are used.

Q # 32) What is the AngularJs Global API?

Reply: It is a combination of global JavaScript functionality that is used to perform tasks such as comparing objects, iterating objects, and converting data.

There are some common API functions like:

  • angular. Lowercase letters: It converts a string to a lowercase string.
  • angular. Capital letter: It converts a string to an uppercase string.
  • angular. isString: It will return true if the current reference is a string.
  • angular. is number: It will return true if the current reference is a number.

Q # 33) What is a provider method in AngularJs?

Reply: A provider is an object that creates a service object by allowing more control.

The $ get () method is used in the provider that returns the service object. The service name and the factory function are the arguments passed to the provider method. AngularJS uses $ require to register new providers.


Q # 34) What is event handling?

Reply: Event handling in AngularJs is very useful when you want to build advanced AngularJs applications.

We need to handle DOM events like mouse clicks, movements, key presses, change events, etc. AngularJs has some listener directives like ng-click, ng-dbl-click, ng-mousedown, ng-keydown, ng-keyup, etc.

Q # 35) What is AngularJ's DOM?

Reply: AngularJs have some directives that encapsulate AngularJs application data in a disabled attribute of the HTML elements.

Example:: The ng-disabled directive encapsulates the application data in the disabled attributes of the HTML DOM element.

Q # 36) What attributes can be used when creating a new AngularJs directive?

Reply: There are several attributes that can be used when creating a new directive.

They include:

  1. Template: It describes an inline template as a string.
  2. Template url: This attribute identifies the AngularJs HTML compiler, which will replace the custom directive in a template with the HTML content in a separate file.
  3. Replace: It replaces the current element if the condition is true, if false appends this statement to the current element.
  4. Transclude: You can move the original children of a directive to a location within the new template.
  5. Scope: A new scope is created for this directive instead of inheriting the parent scope.
  6. Regulator: A controller is created that publishes an API for communication between instructions.
  7. Need: Another policy must be in place for the current policy to work efficiently.
  8. Shortcut: It changes the resulting DOM element instances, adds event listeners, and sets up data binding.
  9. Compile: It changes the DOM template for features in copies of a directive as used in other directives. Your compilation function can also return join functions to modify the resulting member instances.

Q # 37) Are nested controllers possible or not in AngularJs?

Reply: Yes, it is possible that nested controllers are defined as classified when using a view.

Q 38) Is AngularJS good for all browsers?

Reply: Yes, it can be used with all browsers like Safari, Chrome, Mozilla, Opera, IE etc. as well as mobile browsers.

Q 39) Define services in AngularJS.

Reply: AngularJS services are the singleton objects or functions that are used to perform specific tasks. It encompasses some business ideas and these purposes can be called controllers, directives, filters, etc.

Q 40) Explain the benefits of AngularJS.

Answer: The benefits include:

  • It supports MVC forms.
  • Organize two types of data binding with AngularJS.
  • It supports mutual client-server communication.
  • It supports simulations.

Q # 41) Difference between service and factory.

Reply: Factories are functions that return the object, while services are constructor functions of the object that are used by a new keyword.


factory - module.factory (`factoryName`, function);

service - module.service (`serviceName`, function);

Q # 42) If both work and service are equivalent, when should I use them?

Reply: The factory provider is preferred with an object, while a service provider is preferred with class.

Q # 43) Difference between AngularJS and React.JS.

Reply: AngularJS is a TypeScript-based JS framework released by Google in October 2010. It is a completely free framework and open source that is used in SPA projects (i.e. Single Page Application projects).

React.JS is a Javascript library developed by Facebook in March 2013 to create the user interface. Reaction components can be used on multiple sides, but not as a SPA (i.e. single side application).

F # 44) Difference between ng-bind and ng-model directives.

Reply: The ng-bind directive has one-way data bindings, data flows only from the object to the user interface, not vice versa (i.e. $ scope >> view), and the ng-model directive has two-way data bindings, data flows between the user interface to the object and vice versa vice versa (ie $ scope >> view and view >> $ scope).

Q # 45) What is the difference between AJAX and AngularJS?

Reply: AJAX stands for Asynchronous JavaScript, which is used to send and get responses from the server without loading the page.

AngularJS is a typescript-based JavaScript framework that follows the MVC pattern.

F # 46) Define ng-if, ng-show and ng-hide.

Reply: The ng-if statement is used as an if clause that removes the HTML element if the expression becomes false.


The ng-show directive is used to display the HTML element when the expression becomes true. And if the expression gets wrong, the HTML element is hidden.


The ng-hide directive is used to hide the HTML element when the expression becomes incorrect.


Both ng-show and ng-hide use the display property method.

Q # 47) What is the difference between ngRoute and UI router?

Reply: ngRoute is a module developed by the AngularJS team and was part of the core AngularJS framework. While UI router was developed by a third party community to overcome ngRoute's problems.

ngRoute is location or url based routing and ui-router is state based routing that allows nested views.

Q # 48) How do I set, get and delete cookies in AngularJs?

Reply: AngularJS has a module called ngCookies. Before injecting ngCookies, Angular-Cookies.js should be included in the application.

  • Set cookies - The put method is used to set cookies in a key value format.
  • Receive cookies - The Get method is used to get cookies.
  • Clear Cookies - The removal method is used to remove cookies.


I'm sure this article would have helped you understand the basics and advanced level of AngularJS.

With these AngularJS interview questions and answers listed here, you can successfully crack any AngularJS interview on a fresher and more experienced level. These are the most common questions asked in the interviews. That's all for now.

This article will help you crack and face any AngularJS related interview !! Hope you enjoyed the full range of tutorials in this AngularJS series!

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