Top AngularJS Interview Questions and Answers

Find below the list of Frequently Asked AngularJS Interview Questions and Answers for both Freshers and Experienced Professionals. Here’s a brief explanation for each of the AngularJS interview questions mentioned in this post with answer.

Table of Contents

Top AngularJS Interview Questions and Answers List

What is AngularJS and what are its benefits?

AngularJS is a JavaScript-based open-source front-end web application framework mainly maintained by Google. Its main goal is to simplify the development and testing of single-page applications and provide a modular architecture for building web applications.

Benefits of AngularJS include:

Two-way data binding, reducing the amount of boilerplate code needed for updates.
Modular architecture for easier maintainability and scalability.
Declarative UI design making it easier to understand the application’s structure.
Easy testing with built-in support for unit testing.
Reusable components and custom directives.
Large community with numerous resources and plugins available.
Strong support for dynamic views and animations.

What is the difference between AngularJS and other JavaScript frameworks?

Architecture: AngularJS uses a modular architecture that allows for easy maintenance and scalability of applications.

Data Binding: AngularJS provides two-way data binding, which updates the view automatically when the model changes, and vice versa.

Directives: AngularJS uses custom HTML tags (directives) to extend the HTML vocabulary and create reusable components.

Testing: AngularJS has built-in support for unit testing, making it easier to test the application.

Dependency Injection: AngularJS uses dependency injection, making it easier to manage dependencies between components.

Templating: AngularJS uses HTML as a template language, making it easier to understand the application’s structure.

What is a directive in AngularJS and what are the different types of directives?

A directive in AngularJS is a custom HTML tag that extends the HTML vocabulary and can add dynamic behavior to an application. Directives are used to create reusable components and encapsulate complex logic into custom HTML tags. WordPress Interview Questions and Answers

There are several types of directives in AngularJS:

Component Directives: These are the most commonly used directives in AngularJS and are used to create reusable components.

Structural Directives: These directives add or remove elements from the DOM based on the value of a condition. Examples include ngIf, ngSwitch, and ngRepeat.

Attribute Directives: These directives change the appearance or behavior of an existing DOM element. Examples include ngClass and ngStyle.

Service Directives: These directives are used to create custom services in AngularJS.

Filter Directives: These directives are used to format data before displaying it in the view. Examples include currency and date filters.

Document Object Model (DOM) Directives: These directives are used to manipulate the DOM. Examples include ngClick and ngBlur.

Explain the concepts of modules, controllers, and scope in AngularJS.

Modules: A module in AngularJS is a container for different parts of an application, such as controllers, services, filters, and directives. Modules help to organize and structure an application, making it easier to maintain and scale.

Controllers: A controller in AngularJS is a JavaScript function that controls a specific part of an application. Controllers define the behavior of a specific view. and they can access and manipulate the data in the model and update the view when necessary.

Scope: A scope in AngularJS is an object that refers to the model and acts as a context for expressions in the view. Scopes provide a way to pass data from the controller to the view and vice versa. Scopes can also be nested, creating a hierarchical structure for the application.

What is the difference between ng-show/ng-hide and ng-if directives?

The ng-show and ng-hide directives in AngularJS are used to show or hide an element based on a condition. The difference between them is that ng-show displays an element when the condition is true, but the element still takes up space in the layout. ng-hide, on the other hand, hides an element when the condition is true, but the element does not take up any space in the layout.

The ng-if directive, on the other hand, adds or removes an element from the DOM based on a condition. When the condition is false, the element is removed from the DOM, and when the condition is true, the element is added back to the DOM. Unlike ng-show and ng-hide, the element does not take up space in the layout when it is removed from the DOM.

In terms of performance, ng-if is generally faster than ng-show and ng-hide because it does not manipulate the visibility of an element but instead adds or removes it from the DOM. However, using ng-if can also have a negative impact on the performance of an application if it involves a lot of elements being added and removed from the DOM frequently. In such cases, ng-show and ng-hide might be a better choice.

What is data binding in AngularJS?

Data binding in AngularJS refers to the automatic synchronization of data between the model and view components. It allows you to link the properties of a model to the properties of a view. So that any change in the model will be reflected in the view and vice versa. This makes it easier to maintain the consistency of the data displayed in the view and the underlying model.

How do you implement routing in AngularJS?

To implement routing in AngularJS, you can use the $routeProvider service, which is part of the ngRoute module.

Here are the steps to set up routing:

Include the ngRoute module as a dependency in your AngularJS app.
Configure the $routeProvider service in your app’s module by using the when() and otherwise() methods.
Use the ng-view directive in your HTML template to specify the location where the content of each route will be displayed.
Use the $location service or the ngHref directive to create links between different routes in your app.

Here is an example of a simple implementation of routing in AngularJS:

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

In this example, two routes are defined for the root URL and the “/about” URL, and the “otherwise” method is used to redirect to the root URL in case of any other URL.

What is the difference between a factory and a service in AngularJS?

In AngularJS, both factories and services are ways to create reusable components for your application. However, there are some differences between them in terms of how they are instantiated and the way they return objects:

Factory: A factory is a function that returns an object. The object is then assigned to a property on the $scope. The returned object can have methods that can be used to manipulate data. Factories are instantiated using the “new” keyword and can have dependencies that can be injected.

Service: A service is a singleton object that is instantiated only once per application. It is a simple constructor function that is invoked with the “new” keyword. Services are used to share data and behavior across multiple parts of an application, and can also have dependencies that can be injected.

How do you implement custom filters in AngularJS?

To implement custom filters in AngularJS, you need to create a filter function and register it with your AngularJS app using the filter() method of the module. The filter function takes an input value, processes it, and returns the processed value.

Here’s an example of how to implement a custom filter:

angular.module('myApp', [])
.filter('reverse', function() {
return function(input) {
return input.split('').reverse().join('');
};
});

In this example, a custom filter called “reverse” is created that reverses the input string. To use this filter in your HTML template, you can specify it as a pipe (|) character in your expression, like this:

<p>{{ 'Hello' | reverse }}</p>

In this example, the filter will be applied to the string “Hello” and will produce the output “olleH”.

Concept of dependency injection in AngularJS.

Dependency injection is a design pattern in AngularJS that allows for the separation of concerns and makes it easier to manage dependencies between different components of an application. It works by having a central component, called the injector, That is responsible for resolving and providing instances of objects (called dependencies) to other components that need them.

The main idea behind dependency injection is that you can pass the dependencies as arguments to the constructor of a component, rather than having the component create or look up the dependencies itself. This makes it easier to test components in isolation and to swap out dependencies for different purposes, such as testing or different environments.

In AngularJS, the injector uses a provider to determine how to create the instances of dependencies, and it can be configured to provide different implementations for different parts of the application. This allows you to manage the dependencies in a centralized way, making it easier to maintain and scale your application.

What is the digest cycle in AngularJS?

The digest cycle in AngularJS is the process by which AngularJS updates the view to reflect changes in the model. It is a continuous loop that checks for changes in the model and updates the view accordingly.

The digest cycle is triggered whenever there is a change in the model, for example. When a user interacts with the view, or when a value in the model changes due to an asynchronous operation. AngularJS uses a dirty checking mechanism to check for changes in the model and updates the view only if necessary.

During the digest cycle, AngularJS processes a queue of watched expressions. Updating the values of the expressions and the corresponding view bindings. The digest cycle continues to run until all expressions have been processed and there are no more changes to the model.

The digest cycle is an important concept in AngularJS, and it ensures that the view is updated in a consistent and efficient manner. It also helps to prevent excessive updates of the view, which can lead to performance issues. Understanding the digest cycle is important for writing efficient and maintainable AngularJS applications.

Role of the $rootScope in AngularJS?

The $rootScope in AngularJS is the top-most scope in the scope hierarchy. It is the parent scope of all other scopes in an AngularJS application. When you create a new scope, it becomes a child scope of the $rootScope.

The $rootScope is used to store data and methods that are shared across the entire application. This makes it possible to share data and behavior between different parts of the application without having to pass it explicitly as a parameter.

In AngularJS, the $rootScope is automatically created when the application bootstraps, and it is accessible from anywhere in the application using the $rootScope property. For example, you can use the $rootScope to store values such as user information or application-wide settings that need to be accessible from multiple parts of the application.

It is important to note that the $rootScope should be used judiciously, as having too many properties or methods on the $rootScope can make it difficult to manage and maintain your application. In general, it is a good practice to limit the use of the $rootScope to global state that is truly shared across the entire application.

Difference between a singleton and a prototype in AngularJS?

A singleton is a design pattern where only one instance of an object is created. and all subsequent calls to create an object of that type return the same instance. This means that any changes made to the object are visible to all parts of the application that use the same instance.

AngularJS interview questions are an important part of evaluating a candidate’s knowledge and expertise in developing front-end web applications. Some of the most common questions include asking about AngularJS’s main features. Such as two-way data binding, directives, and dependency injection.

The interviewer may also ask about the candidate’s experience with AngularJS and its ecosystem, including working with different modules and services, as well as integrating with other technologies. Additionally, questions on coding challenges or scenarios using AngularJS may be included to test the candidate’s practical skills.

AngularJS interview questions is also important for the candidate to have a solid understanding of AngularJS’s core concepts. As well as be able to explain and apply their knowledge in a practical setting.

AngularJS Interview Questions