Angular Interview Questions and Answers for 2025

The default module-loading strategy is eager loading, in which, the feature modules under eager loading are loaded before the application starts. In general, it is used for small-size applications. On the other hand, Lazy loading loads the feature modules when there is a demand, making the application faster. It is best for bigger applications where all the modules are not required at the start.

Angular's three fundamental building blocks are Components, modules, and services. Components are the most minor, self-contained units in an Angular application. They are typically used to represent a view or UI element, such as a button or a form input field. Modules are larger units that group one or more related components. Services are singleton objects that provide specific functionality throughout an Angular application, such as data access or logging.

In Angular, one-way data binding is a technique that allows you to bind the value of a component property to an element property in the template, or to interpolate the value of a component property in the template HTML. One-way data binding is a unidirectional process, meaning that changes to the component property are reflected in the UI element, but changes to the UI element are not reflected in the component property. 

One-way data binding is denoted by square brackets, [], and it is used to bind a component property to an element property. 

For example: 

<input type="text" [value]="name"> 

In this example, the value property of the input element is bound to the name property of the component using one-way data binding. 

On the other hand, two-way data binding is a technique that allows you to bind a component property to an element property in such a way that changes to either the component property or the element property are reflected in the other. Two-way data binding is a bidirectional process, meaning that changes to the component property are reflected in the UI element, and changes to the UI element are reflected in the component property. 

Two-way data binding is denoted by square brackets and parentheses, [()], and it is used to bind a component property to an element property. 

For example: 

<input type="text" [(ngModel)]="name"> 

In this example, the ngModel directive is used to bind the value property of the input element to the name property of the component using two-way data binding. 

One-way data binding is a simpler and more efficient technique than two-way data binding, as it only updates the UI element when the component property changes, and it does not require additional logic to manage the flow of data between the component and the UI element. However, two-way data binding can be more convenient in some cases, as it allows you to update the component property and the UI element simultaneously, without having to write additional code. 

The hooks available in AngularJS are as follows:- 

1. ngOnInit() 
2. ngOnChanges(), 
3. ngDoCheck(), 
4. ngAfterContentInit(), 
5. ngAfterContentChecked(), 
6. ngOnDestroy(), 
7. ngAfterViewChecked(), and 
8. ngAfterViewInit(). 

In AngularJS, the $routeProvider is a service that is used to configure the routes for an application. It is typically used in the configuration phase of an AngularJS application, and it is responsible for mapping URLs to views and controllers. 

Here is an example of how you might use the $routeProvider service in an AngularJS application. Lets see how to answer this angular life cycle interview questions: 

angular.module('myApp', ['ngRoute']) 
 .config(function($routeProvider) { 
    $routeProvider 
      .when('/', { 
        templateUrl: 'views/home.html', 
        controller: 'HomeController' 
      }) 
      .when('/about', { 
        templateUrl: 'views/about.html', 
        controller: 'AboutController' 
      }) 
      .otherwise({ 
        redirectTo: '/' 
      }); 
  }); 

In this example, the $routeProvider is being used to configure two routes in the application: one for the root URL (/) and one for the /about URL. For each route, the $routeProvider specifies the template that should be displayed and the controller that should be used to handle the route. If the user navigates to a URL that does not match any of the routes configured with the $routeProvider, the otherwise() method is used to redirect the user back to the root URL. 

It is a lifecycle hook that is usually called after the completion of initializing all date-bound properties of a directive. “ngOnInit ()” is defined as

Interface OnInit 
 { 
   ngOnInit () : void 
} 

In AngularJS, a pipe is a function that takes in data as input and returns a transformed version of that data. Pipes are a useful feature in AngularJS as they allow you to transform data in a declarative way within templates. 

Here is an example of how you might use a pipe in an AngularJS template: 

<p>{{ someText | uppercase }}</p> 

In this example, the uppercase pipe is being used to transform the someText variable to uppercase. The resulting HTML output would be: 

<p>SOME TEXT</p> 

AngularJS comes with a number of built-in pipes, including uppercase, lowercase, and currency. You can also create your own custom pipes if you need to perform more specialized data transformations. 

To use a pipe in an AngularJS template, you place the pipe name after the variable that you want to transform, separated by a vertical bar (|). You can chain multiple pipes together by using multiple vertical bars, like this: 

<p>{{ someText | uppercase | reverse }}</p> 

In this example, the reverse pipe would be applied to the output of the uppercase pipe, resulting in the someText variable being transformed to uppercase and then reversed. 

When we load the page in the browser, the following process takes place: 

• First, the HTML document of the page loads, then the web browser evaluates it. After that, the Javascript file is loaded, and a global object is created. Then, controller functions are executed. Javascript registers those functions. 
• Javascript scans views and apps via HTML. After scanning the view, it is connected to the controller function. 
• AngularJs shows the data handled by the controller and controller functions with a view. Ultimately, the page gets ready.

The process of bootstrapping an Angular application is relatively simple. The following is a step-by-step guide to bootstrapping an Angular application: 

• Create an HTML file and add a div with the attribute "ng-app" and the value of the name of your module. This tells Angular to bootstrap your application using this module. 
• Create a new file called app.js, this file will contain your module. Add the following code to it: 

 var app = angular.module('myApp', []); 

• Add a script tag in your HTML file that references your app.js file. 

<script src="app.js"></script> 

• Create a new file called controller.js, this file will contain your controller. Add the following code to it: 

app.controller('MyController', function($scope) { 
  $scope.message = 'Hello, Angular!'; 
}); 

• Add another script tag in your HTML file that references your controller.js file. 

<script src="controller.js"></script> 

• In your HTML file, add an element with the attribute "ng-controller" and the value of the name of your controller. This tells Angular to use this controller to control the behavior of the elements within it. 

<div ng-controller="MyController"> 
  {{message}} 
</div> 

Finally, you can run your application in any browser, you should see the message "Hello, Angular!" displayed on the page. 

In conclusion, bootstrapping an Angular application is relatively simple. With the use of a ng-app attribute,app.js file and ng-controller attribute, you are able to create a complete Angular program. The angular documentation is a good resource to refer when creating a new angular project.

To break it down in the simplest way, AngularJS initializes automatically upon the DOMContentLoaded event or when the angular.js script is read if, at that time document.readyState is set to 'complete'. At this point, Angular looks for the ng-app directive, which is the root of the AngularJS compilation process. 

• If the ng-app directive is found, then Angular will: 
• Load the module associated with the directive. 
• Create the application injector 
• Start a compilation of DOM from the ng-app directive, the root of the compilation.

The AngularJS Global API is a set of global JavaScript functions for performing common tasks, such as:- 

• Converting Data 
• Iterating Objects 
• Comparing Objects 

AngularJS provides a number of global APIs that you can use in your application. These APIs are accessible from anywhere within your application, and they provide common functionality that you might need. 

Here are some examples of Angular Js global  APIs asked in the angular practical interview questions:  

• angular.module: This API is used to create and retrieve AngularJS modules. 
• angular.element: This API is used to wrap DOM elements as AngularJS elements, which can be used to perform AngularJS actions on the elements. 
• angular.bootstrap: This API is used to manually bootstrap an AngularJS application. 
• angular.copy: This API is used to create a deep copy of an object. 
• angular.equals: This API is used to determine if two objects or values are equal. 
• angular.extend: This API is used to extend the properties of an object with the properties of another object. 
• angular.forEach: This API is used to iterate over an object or an array and perform a function on each item. 

Yes, it is possible to create nested controllers in AngularJS, the example is as follows:-

Example:  

{{msg}} {{name}}! 
Hi {{name}}! 
{{msg}} {{name}}! 
Your name is {{name}}.

ViewEncapsulation recognizes the component styles and shows whether a particular component will affect the entire application. Moreover, it allows users to use the DOM shadow. 

Angular provides three types of ViewEncapsulation that are as follows:- 

• ViewEncapsulation.emulated: The styles in this type are used in other HTML, spread the components. 
• ViewEncapsulation.native: The styles in this type are used in other HTML but do not spread the components. 
• ViewEncapsulation.none: It defines the component style that is visible to all components of the application. 

To understand the angular concepts for interview, you must also know how to use the ng-include. The ng-include directive is used in AngularJS to include an HTML fragment from a separate file in the main HTML template. This can be useful in a number of situations:

• To break up a large HTML template into smaller, more manageable files.
• To reuse a common HTML fragment in multiple templates.
• To conditionally include an HTML fragment based on a condition.

Here is an example of how you might use the ng-include directive in an AngularJS template:

<div ng-include="'views/header.html'"></div> 

In this example, the ng-include directive is used to include the contents of the header.html file in the main template. The ng-include directive takes an expression that specifies the URL of the HTML fragment to include.

You can also use the ng-include directive with variables, like this:

<div ng-include="templateUrl"></div> 

In this example, the value of the templateUrl variable is used to specify the URL of the HTML fragment to include. This allows you to dynamically specify the HTML fragment to include based on the value of the templateUrl variable.

Overall, the ng-include directive is a useful tool for including HTML fragments in your AngularJS templates, which can help you to organize and modularize your templates.

Other than these questions, you may be asked to answer some angular scenario based interview questions. For such questions, you can read about online courses or the provided platforms.

Angular has multiple building blocks with different purposes and goals: 

• Components 
• Modules 
• Directives 
• Decorators 
• Pipes 
• Data Binding 
• Templates 
• Metadata 
• Services 
• Dependency Injection

In AngularJS, a scope is an object that represents the context in which a particular piece of code is executed. Scopes are used to provide separation of concerns in an AngularJS application and to facilitate communication between different parts of the application. 

There are two types of scopes in AngularJS: root scope and child scopes. The root scope is the top-most scope in the scope hierarchy and it is the parent of all other scopes. Child scopes are created whenever a new controller or directive is defined in an AngularJS application. 

Scopes provide a number of important features in AngularJS: 

• They provide a context for expressions to be evaluated in. 
• They provide a way to bind data from the view to the controller. 
• They provide a way to bind data from the controller to the view. 
• They provide a way to share data between controllers. 

Scopes are also used to propagate events between different parts of an AngularJS application. For example, you can use the $emit method of a scope to raise an event that will be propagated up the scope hierarchy, or you can use the $on method to listen for events that are emitted by other scopes. 

Overall, scopes are a fundamental concept in AngularJS and they play a central role in the architecture of an AngularJS application. 

One of the common Angular questions for interview every year, don't miss this one.

In AngularJS, the $rootScope is the top-most scope in the scope hierarchy. It is the parent of all other scopes and it is created by the AngularJS framework when the application is bootstrapped. 

The $rootScope provides a context for expressions to be evaluated in and it is also used to propagate events between different parts of an AngularJS application. You can use the $emit method of the $rootScope to raise an event that will be propagated down the scope hierarchy, or you can use the $on method to listen for events that are emitted by the $rootScope or any of its descendant scopes. 

Here is an example of how you might use the $rootScope in an AngularJS application: 

angular.module('myApp').run(function($rootScope) { 
  $rootScope.someData = 'Hello, world!'; 
}); 

In this example, the someData property is being added to the $rootScope, which makes it available to all other scopes in the application. You can then use the someData property in a template like this: 

<div>{{ someData }}</div> 

The $rootScope is a powerful tool in AngularJS, but you should be careful not to overuse it. It is generally a good idea to avoid adding too much data to the $rootScope and instead use it only for data that needs to be shared across the entire application. 

Connect capability controls the DOM( Archive Article Model ) component utilizing a custom mandate. The link option in the custom directive both registers and updates the DOM. Here are a few types of Link Functions in AngularJS.  

• Scope: – It is a scope object for Angular.  
• Feature: – This customized directive matches the jqLite-wrapped element.  
• Attrs: – It is a hash object with key-valprs consisting of normalized attribute names and their values.  

Each Precise application has a root scope and can have quite a few youngster scopes. When an Angular application is created, the root scope is created, but directives can also create new child scopes. A new child scope is added to the parent scope as a child when it is made. Typically, this tree of child scopes follows the DOM to which they are attached.

There are several essential Building Blocks of Angular, as follows:  

• Modules – Angular maintains modularity. Clearly speaking, Module refers to the file which classifies similar directives, services, directives, and pipes.  
• Components – A component touches on a Javascript class, which, one after another, is furnished as a section in the view.  
• Templates – The component's view is marked out through templates. Templates are primarily the HTML that developers can use on their pages.  
• Metadata – In Angular, Metadata tells a javascript class and how it should be prepared on the screen.  
• Directives – In angular, Directives help the developers to add on the dynamic of the DOM elements. Angular primarily has two kinds of directives – Structural Directives and Attribute Directives.  
• Services - A service is a class that includes any feature, function, or feature with a defined and specific purpose, like handling HTTP requests' side effects.  
• Dependency Injection - We can inject any service or dependency using Dependency Injection, enabling us to provide its instance throughout the entire web application or a specific module or component.  

This is one of the most common Angular advanced interview questions you can expect to come across during Angular interviews.

In AngularJS, you can apply DOM by the following:  

• DOM elements are used to construct documents.  
• DOM elements allow a programmer to navigate the structure of a document.  
• With DOM elements, a programmer can add elements and content.  
• DOM elements permit content and elements to be modified by programmers.

In AngularJS, an expression is a JavaScript-like code snippet that is evaluated by the AngularJS framework. Expressions are used to bind data from the view to the controller and to manipulate values in the view. 

Expressions are similar to JavaScript expressions, but they have a few differences: 

• They do not support control structures (e.g., if statements, for loops). 
• They do not support creating variables or functions. 
• They can only access the properties of the $scope object. 

Expressions are usually used in templates, but they can also be used in controllers, directives, and other parts of an AngularJS application. 

Here is an example of an expression in an AngularJS template: 

<div>{{ someValue + 1 }}</div> 

In this example, the expression someValue + 1 is being evaluated and the result is being inserted into the HTML output. If the value of someValue is 5, the output would be 6. 

Expressions are a useful tool in AngularJS for binding data from the view to the controller and for manipulating values in the view. They are often used in conjunction with directives and controllers to create interactive and dynamic applications. 

AngularJS Routes allow programmers to develop URLs for different content within a web application. The ngRoutes Module allows the developers to access several application pages without reloading the application.  

Important Note: The routes are set up with the help of $routeProvider. Determining which page to display when a user clicks a link is helpful. The when() or otherwise() methods are supported.

In AngularJS, an injector is a service that is responsible for instantiating objects and resolving dependencies. Injectors are used to create and manage the dependencies that are required by an AngularJS application. 

An injector is created whenever an AngularJS application is bootstrapped, and it is used to resolve the dependencies that are needed by the application. When a dependency is needed, the injector looks for an existing instance of the dependency and returns it if it exists. If the dependency does not exist, the injector creates a new instance of the dependency and returns it. 

In AngularJS, you can define dependencies by using the $inject property or the inject function. Here is an example of how you might define dependencies in an AngularJS service: 

angular.module('myApp').service('customService', ['$http', function($http) { 
  this.someMethod = function() { 
    // service logic goes here 
  }; 
}]); 

In this example, the customService service has a dependency on the $http service. The $inject property is used to specify the dependencies that the service has, and the dependencies are then injected into the service's function when the service is instantiated. 

Overall, the injector is a central component of the AngularJS dependency injection system, and it plays a crucial role in the architecture of an AngularJS application. 

In AngularJS, a factory is a function that returns an object. Factories are used to create objects that can be used as dependencies in an AngularJS application. 

Here is an example of a factory in AngularJS: 

angular.module('myApp').factory('customFactory', function() { 
  return { 
    someMethod: function() { 
      // factory logic goes here 
    } 
  }; 
}); 

In this example, the customFactory factory is a function that returns an object with a single method called someMethod. You can then inject the customFactory into a controller or other component of your application and use the someMethod method like this: 

angular.module('myApp').controller('MyController', function(customFactory) { 
  customFactory.someMethod(); 
}); 

Factories are a useful way to encapsulate complex logic and reuse it throughout an AngularJS application. They are often used in conjunction with services and controllers to create modular and reusable components in an AngularJS application. 

Overall, the factory method is a design pattern that is used to create objects in a decoupled and modular way, and it is a central concept in AngularJS. 

You should be ready for any Angular questions for interview and SPA is one such topic.

A single-page application (SPA) is a web application that loads a single HTML page and dynamically updates the page as the user interacts with the application. In a SPA, all the necessary code (HTML, JavaScript, and CSS) is loaded up front, and the application is then able to handle navigation and display views without reloading the entire page. 

AngularJS is a popular framework for building single-page applications because it provides a rich set of features for building client-side applications, including a powerful routing system and a comprehensive set of built-in directives. 

Here is an example of how you might use AngularJS to build a single-page application: 

angular.module('myApp', ['ngRoute']) 
  .config(function($routeProvider) { 
    $routeProvider 
      .when('/', { 
        templateUrl: 'views/home.html', 
        controller: 'HomeController' 
      }) 
      .when('/about', { 
        templateUrl: 'views/about.html', 
        controller: 'AboutController' 
      }) 
      .otherwise({ 
        redirectTo: '/' 
      }); 
  }); 

In this example, the $routeProvider service is being used to configure the routes for the application. When the user navigates to a particular URL, the $routeProvider will display the appropriate template and invoke the corresponding controller. This allows the application to handle navigation and display different views without reloading the entire page. 

Overall, single-page applications are a popular approach to building web applications because they provide a smooth and responsive user experience and can be faster and more efficient than traditional multi-page applications. AngularJS is a powerful framework for building single-page applications, and it is widely used for this purpose.

In AngularJS, the $scope is an object that represents the context in which a particular piece of code is executed. Scopes are used to provide separation of concerns in an AngularJS application and to facilitate communication between different parts of the application. 

Every AngularJS application has at least one root scope, and additional scopes are created whenever a new controller or directive is defined. Scopes provide a number of important features in AngularJS: 

• They provide a context for expressions to be evaluated in. 
• They provide a way to bind data from the view to the controller. 
• They provide a way to bind data from the controller to the view. 
• They provide a way to share data between controllers. 

Scopes are also used to propagate events between different parts of an AngularJS application. For example, you can use the $emit method of a scope to raise an event that will be propagated up the scope hierarchy, or you can use the $on method to listen for events that are emitted by other scopes. 

Overall, the $scope is a fundamental concept in AngularJS and it plays a central role in the architecture of an AngularJS application.

On the other hand, the Integrated Development Environment (IDE) is a program that helps you write flawless code and reduces developers' effort by optimizing the entire development process. It aids in software integration and operating system analysis. The best angular Tools and IDE are: 

• Angular IDE – Precise IDE is profoundly utilized for a quicker and more compelling turn of events. It is an independent plugin that works in conjunction with the Eclipse plugin. Although it was initially used to manage tsconfig.json, it is explicitly designed for Angular.  
• Webstorm – Webstorm, a powerful code editor developed by Jetbrains and IntelliJ, is an excellent choice for coding TypeScript-based Angular 2 applications.  
• Visual Studio Code – Visual Studio Code by Microsoft for Windows, Mac OS X, and Linux. It is a TypeScript-compatible source code editor that supports functions, imported modules, and intelligent code completion based on variable types.  
• Sublime Text – When it comes to code and markup editing, it is a sophisticated option. Nowadays, it is a popular code editor. It has outstanding performance and a user interface that is clean and streamlined.  
• Brackets – It is the best choice for a code editor if you want a perfect blend of visual tools. Brackets is an Angular-based IDE that is both lightweight and extremely powerful. It can be used to create mobile and web applications.  
• Atom – It was developed by GitHub and is favored by users due to its simple installation and accessible environment customization. The Atom TypeScript package can be installed to enhance your TypeScript application experience with Angular apps. APM CLI serves as a built-in package installer as well.  
• Aptana Studio – It is an Angular-specific open-source IDE. It is widely used for JavaScript development and is based on Eclipse. The AngularJS Eclipse extension can be included. It is compatible with numerous other libraries and frameworks. Aptana Studio is available as an Eclipse Plug-in and a stand-alone version.  
• ALM IDE – A cloud-based TypeScript IDE is available from ALM. It removes all barriers to TypeScript use and is simple to use. You can code quickly in TypeScript projects with it. It can be installed easily with just one npm command. On Raspberry, you can even create projects using TypeScript.  

The $watch() function monitors changes to $scope object variables. In most cases, AngularJS will create the $watch() function internally to handle application-wide changes to variables.