TCS AngularJS Developer Interview Questions

On September 7, 2024, Posted by CRS Info Solutions , In Angular, With Comments Off

Table of Contents

What are the core features of AngularJS?
Explain the concept of two-way data binding in AngularJS?
How does AngularJS handle dependency injection?
How do you create a custom directive in AngularJS?
What are services in AngularJS?
Explain how routing works in AngularJS?
How does AngularJS handle form validation?
Can you explain the digest cycle in AngularJS?
What are the differences between AngularJS and Angular?

When preparing for an interview as an AngularJS Developer, especially with a leading technology company like TCS, it’s essential to understand both the core concepts and advanced features of AngularJS. AngularJS, being one of the most popular JavaScript frameworks, is widely used for building dynamic web applications. The framework’s ability to extend HTML with additional features and simplify the development process through two-way data binding, dependency injection, and powerful directives makes it a preferred choice for developers. However, mastering AngularJS requires a deep understanding of its architecture, components, and the best practices for building scalable and maintainable applications.

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In an interview setting, you can expect questions that assess your knowledge of AngularJS fundamentals, such as data binding, services, and routing, as well as your ability to handle more complex topics like custom directives, performance optimization, and security implementation. These questions are designed to gauge not only your technical skills but also your problem-solving abilities and how effectively you can apply your knowledge to real-world scenarios. Preparing thoroughly for these questions will help you demonstrate your expertise and readiness to tackle the challenges of working on sophisticated AngularJS projects.

1. What are the core features of AngularJS?

When I work with AngularJS, I rely on several core features that make it an effective framework for building dynamic web applications. First, I appreciate the two-way data binding, which automatically synchronizes changes between the user interface and the data model. This feature alone simplifies a lot of the work I would otherwise have to do manually. Another key feature I use frequently is directives, which allow me to extend HTML with custom elements and behaviors. AngularJS also provides controllers, which I use to manage my application’s data and business logic. Additionally, services in AngularJS are invaluable to me for handling reusable logic, such as making HTTP requests. Lastly, AngularJS’s dependency injection system is a great help in keeping my code modular and easy to test.

2. Explain the concept of two-way data binding in AngularJS.

Two-way data binding in AngularJS is a feature that I find incredibly powerful. It automatically synchronizes the data between the model (the data in my JavaScript code) and the view (the HTML displayed to the user). This means that when I update a value in my model, the change is immediately reflected in the view, and if a user updates something in the view, the model is updated accordingly. This bi-directional flow of data makes it much easier for me to develop and maintain interactive applications because I don’t have to manually update the DOM or handle complex event listeners.

Read more about Introduction to Angular: A Beginner’s Guide

3. How does AngularJS handle dependency injection?

When I use AngularJS, I take advantage of its built-in dependency injection (DI) system. DI in AngularJS allows me to define dependencies for components like controllers, services, and directives, and AngularJS automatically provides them when needed. Instead of hard-coding dependencies, I can inject them as parameters, making my application more modular and easier to test. For instance, if I need to use a service in a controller, I simply specify it as a dependency, and AngularJS takes care of the rest. This approach helps me keep my code clean and maintainable.

4. What is the difference between $scope and $rootScope in AngularJS?

In my experience working with AngularJS, I’ve learned that $scope and $rootScope serve different purposes. $scope is the scope object that I use within a specific controller to bind data to the view. Each controller in my application has its own $scope, which makes it easy to manage data at the component level. On the other hand, $rootScope is a special scope that acts as the parent of all $scope objects. If I need to share data or functions across multiple controllers, I can attach them to $rootScope. However, I use $rootScope sparingly to avoid potential issues with global state.

5. How do you create a custom directive in AngularJS?

When I need to create a custom directive in AngularJS, I start by using the directive function. This allows me to define reusable components or extend HTML with new behavior. For example, I might create a custom directive to encapsulate a piece of functionality, such as a reusable form component. In the directive definition, I specify the directive’s name, restrict its usage to an element or attribute, and provide a template or template URL. I also define the directive’s scope and link functions to interact with the DOM. This approach helps me create modular and reusable components that I can easily integrate into my application.

6. What are services in AngularJS, and how are they different from factories?

When I work with AngularJS, I frequently use services to encapsulate and share reusable code across my application. Services in AngularJS are singleton objects, which means that they are instantiated only once and shared across the entire application. I use services to handle things like data access, business logic, or utility functions that I need in multiple places. The main difference between services and factories is in how they are created. When I define a service, I use the service method, and AngularJS uses the new keyword to instantiate the service. With factories, I use the factory method, which returns an object or a function that AngularJS will call to create the instance. I tend to use services when I need a class-like object and factories when I want more control over the creation of the object.

Read more about Directives in Angular

7. Explain how routing works in AngularJS.

In AngularJS, routing is something I use to navigate between different views or components within a single-page application. To handle routing, I rely on the ngRoute module, which allows me to define routes and associate them with specific templates and controllers. For example, if I’m building an application with multiple pages, I can use routing to load different templates based on the URL without refreshing the entire page. I define the routes in my configuration using the $routeProvider service, specifying the path, template, and controller for each route. This makes it easy for me to create a seamless, multi-view experience within my application.

8. What are AngularJS filters, and how are they used?

AngularJS filters are a feature I use to transform data before displaying it in the view. Filters allow me to format data, such as converting text to uppercase, formatting dates, or filtering arrays. For instance, I might use the currency filter to format a number as a currency, or the filter filter to search within an array. I apply filters directly in the HTML view using the pipe (|) symbol. For example, {{ amount | currency }} would format the amount variable as currency in the view. Filters are a simple yet powerful tool that helps me ensure that the data presented to the user is clear and properly formatted.

Understanding Components and Modules in Angular

10. What is the purpose of ng-model in AngularJS?

The ng-model directive is one of the features I use most often in AngularJS. It creates a two-way binding between the form elements in the view and the data in my model. When I use ng-model, any changes the user makes to the form input are automatically reflected in the corresponding model variable, and any changes to the model variable are instantly updated in the view. This makes it really easy for me to keep the UI in sync with the underlying data. For example, if I have an input field for a user’s name, I can bind it to a model variable with ng-model="userName", and AngularJS will take care of synchronizing the value between the input field and the model.

11. How would you optimize the performance of an AngularJS application?

When it comes to optimizing the performance of an AngularJS application, I take several steps to ensure that the app runs smoothly and efficiently. First, I try to minimize the number of watchers in my application, as too many can slow down the digest cycle. I do this by avoiding unnecessary bindings and using one-time bindings (::) where possible. Additionally, I break down large, complex controllers and views into smaller, more manageable components. I also leverage AngularJS’s built-in directives like ng-if and ng-repeat efficiently by using them conditionally and filtering or limiting data before it reaches the view. Furthermore, I pay attention to how I manage $http requests, ensuring that they are as efficient as possible by using caching, and I avoid redundant or unnecessary calls. Lazy loading modules and assets can also help reduce the initial load time. Lastly, I make sure to use minification and compression techniques to reduce the size of the final JavaScript files.

12. Can you explain the digest cycle in AngularJS?

The digest cycle is something I’ve had to understand deeply to work effectively with AngularJS. It’s the process by which AngularJS checks for changes in the application’s data model and updates the DOM accordingly. When a scope variable changes, AngularJS starts a digest cycle, during which it compares the current value of each watched variable with its previous value. If a change is detected, the corresponding binding in the view is updated. This process continues until there are no more changes detected, which may involve multiple iterations, known as “dirty checking.” Understanding the digest cycle helps me write more efficient code, as I can minimize unnecessary changes that would trigger additional cycles.

13. What are the differences between AngularJS and Angular?

When I compare AngularJS (also known as Angular 1.x) with Angular (Angular 2 and above), I see several significant differences. AngularJS is based on JavaScript, while Angular uses TypeScript, which is a superset of JavaScript that adds static types. This shift to TypeScript in Angular helps me catch errors early in the development process. AngularJS relies heavily on controllers and scope, whereas Angular uses a component-based architecture, which allows for a more modular and maintainable codebase. Additionally, Angular introduces a more powerful and flexible dependency injection system compared to AngularJS. The performance is also enhanced in Angular, thanks to the introduction of Ahead-of-Time (AOT) compilation, which compiles HTML and TypeScript code during the build process rather than at runtime. This shift results in faster rendering and better overall performance. Finally, Angular comes with built-in support for mobile development, making it easier for me to build responsive and mobile-friendly applications.

Read more about routing and navigation in Angular

14. How would you handle asynchronous calls in AngularJS?

Handling asynchronous calls in AngularJS is something I do often, especially when making HTTP requests. I usually rely on AngularJS’s $http service, which returns a promise. I can then use the .then() method to handle the response when the promise is resolved or .catch() to handle any errors. This approach allows me to manage asynchronous operations in a clean and manageable way. For example, if I’m fetching data from a server, I might use $http.get(url).then(function(response) { ... }) to process the data once it’s returned. I can also use the $q service to create my own promises, which gives me more control over how and when asynchronous code executes. This flexibility is really useful when I need to coordinate multiple asynchronous tasks.

Read more about Angular Material and UI Components

15. Describe how to implement authentication and authorization in an AngularJS application.

Implementing authentication and authorization in an AngularJS application is crucial for securing the app. When I need to add these features, I usually start by creating a service to handle authentication logic, such as logging in, logging out, and checking user credentials. This service might interact with a backend API to verify user details and generate a token.

I then store this token in the client (usually in localStorage or sessionStorage) and attach it to HTTP requests to authenticate subsequent API calls. For authorization, I use route guards or interceptors to prevent unauthorized users from accessing certain routes or parts of the application. I also often include logic in my controllers to check the user’s role and restrict access to features based on that role. This setup allows me to maintain a secure and user-friendly application that controls access at both the client and server levels.

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