Interview Questions on Full Stack Development Experienced Level!! Part 1

As the demand for full stack developers continues to grow, hiring managers and recruiters are looking for experienced candidates who can demonstrate a diverse range of skills and knowledge in front-end and back-end development. To assess the technical abilities of potential candidates, it's important to ask the right interview questions that cover the key areas of full stack development.

In the Part 1 of this article, we'll provide a comprehensive list of interview questions for experienced full stack developers. We'll cover topics such as front-end development, back-end development, database management, and more. These questions will help you assess the technical skills and experience of potential candidates and ensure that you hire the right person for the job.

Q1. State the difference between blue/green deployment and rolling deployment.

Both blue/green and rolling deployment are deployment strategies used to update software applications with minimal downtime and risk. However, there are some key differences between the two:

• Blue/Green Deployment: In this strategy, two identical environments (blue and green) are set up, with only one active at a time. The current live environment is referred to as blue, while the new environment is referred to as green. When a new version of the application is ready, the traffic is switched from the blue environment to the green environment, which becomes the new live environment. This strategy allows for an instant rollback in case of any issues.

• Rolling Deployment: In this strategy, the new version of the application is gradually rolled out to a small subset of users at a time. The traffic is gradually shifted from the old version to the new version in a controlled and incremental manner until all users are on the new version. This strategy is useful when the application cannot be taken down for maintenance all at once or when there is a need to test the new version with a smaller subset of users before rolling it out to everyone.

Q2. Explain the inversion of control.

Inversion of Control (IoC) is a software design pattern that is often used in full-stack development. It refers to the process of decoupling software components and dependencies, allowing for greater flexibility and extensibility in the codebase.

In traditional software design, the application code has control over the flow of execution and the dependencies it requires. In contrast, with IoC, the control is inverted so that the framework or container has control over the flow of execution and the dependencies.

This means that instead of the application code having to instantiate and manage its dependencies manually, the framework or container handles this process for the application. The framework is responsible for identifying dependencies, instantiating objects, and injecting them into the appropriate components.

Some popular IoC frameworks used in full-stack development include Spring for Java, Angular for JavaScript, and Flask for Python. Overall, IoC is a powerful tool that can greatly improve the quality and flexibility of full-stack applications.

Q3. What do you mean by referential transparency in functional programming?

Referential transparency is a key concept in functional programming that refers to the property of a function that always produces the same output for a given input, regardless of when and where it is called. In other words, a referentially transparent function is deterministic and does not depend on any external state or context.

A function that exhibits referential transparency can be replaced with its result value without affecting the behavior of the program. This makes it easier to reason about the function and its behavior since it does not have any side effects or dependencies on external factors.

Some common examples of referentially transparent functions include mathematical functions such as addition and multiplication, as well as string and list operations that do not modify the original data structure. In contrast, functions that rely on mutable states, global variables, or input/output operations are not referentially transparent and can introduce unpredictability and complexity in the program.

Q4. State the difference between normalization and denormalization.

Normalization and denormalization are both techniques used in database design to optimize data storage and retrieval. The key difference is how they handle data redundancy and dependency.

Normalization is the process of organizing data in a database by breaking down tables into smaller, more specialized tables, each with a unique set of attributes. The goal of normalization is to eliminate data redundancy and to ensure that each data element is stored in one and only one place. Normalization also helps to ensure data consistency and minimize data anomalies that may arise due to data duplication.

Denormalization, on the other hand, involves intentionally adding redundant data to a database table to improve performance or simplify queries. This technique is used when data retrieval speed is more important than data storage efficiency. Denormalization can be useful in situations where the application needs to perform complex queries on large datasets or where data retrieval speed is critical.

Q5. What is Promise and explain its states?

A Promise is a JavaScript object that represents the eventual completion (or failure) of an asynchronous operation and its resulting value. A Promise is an alternative to traditional callback-based approaches for handling asynchronous operations in JavaScript.

A Promise has three possible states:

• Pending: This is the initial state of a Promise, indicating that the asynchronous operation has not yet been completed. The Promise is still waiting for the operation to be complete, and the resulting value is not yet available.

• Fulfilled: This state indicates that the asynchronous operation has been completed successfully, and the resulting value is available. At this point, the Promise then method can be used to retrieve the value.

• Rejected: This state indicates that the asynchronous operation has failed, and the reason for the failure is available. At this point, the Promise's catch method can be used to handle the error.

Promises are often used in combination with asynchronous functions and other asynchronous operations, such as HTTP requests and file I/O. They provide a clean and concise way to handle the results of asynchronous operations and avoid callback hell, where multiple nested callbacks can make code difficult to read and maintain.

Promises also have additional methods, such as final and all, that allow for more advanced handling of asynchronous operations. The final method allows for cleanup tasks to be performed regardless of whether the operation succeeded or failed, while all method allows for multiple Promises to be executed in parallel and their results to be combined into a single Promise.

Q6. State the difference between GET and POST.

GET, and POST are two HTTP methods used for sending data between a client (such as a web browser) and a server. The main differences between them are:

• Purpose: The GET method is used to request a resource from the server, while the POST method is used to submit data to be processed by the server.

• Data transmission: The GET method sends data as part of the URL query string, while the POST method sends data in the request body.

• Data size: The GET method is limited by the maximum length of a URL, which can be around 2,000 characters depending on the browser and server configuration. In contrast, the POST method can handle much larger amounts of data.

• Caching: The GET method can be cached by the browser, while the POST method cannot be cached. This means that subsequent GET requests for the same resource can be served from the browser's cache, improving performance.

• Security: The GET method is less secure than the POST method since the data is sent in the URL, which can be intercepted and read by third parties. In contrast, the POST method sends data in the request body, which is not visible in the URL and can be encrypted for added security.

Q7. Explain the Restful API and write its usage.

A RESTful API (Representational State Transfer API) is a type of web API that is designed to be simple, lightweight, and scalable. It is based on the principles of the REST architecture, which defines a set of guidelines for building web services that are loosely coupled, stateless, and easily accessible over HTTP.

A RESTful API uses HTTP methods (such as GET, POST, PUT, and DELETE) to perform operations on resources (such as data objects) that are identified by unique URLs (known as endpoints). Each resource is represented in a specific format, such as JSON or XML, and can be accessed by sending HTTP requests to the corresponding endpoint.

The main advantages of a RESTful API are

• Simplicity.

• Scalability.

• Interoperability.

• Flexibility.

Usage of a RESTful API:

• Retrieving data.

• Creating data.

• Updating data.

• Deleting data.

Overall, a RESTful API is a simple and scalable way to build web services that can be accessed by a wide range of clients using standard HTTP protocols. It is widely used in modern web development and is an essential tool for building web applications and services.

Q8. Do you know how to prevent a bot from scraping your publicly accessible API?

Yes, there are a few methods you can use to prevent bots from scraping your publicly accessible API:

• Implement API keys: You can require API keys for access to your API. This will allow you to track and limit the usage of your API. You can also revoke API keys if they are being used for malicious purposes.

• Rate limiting: You can limit the number of requests that can be made to your API within a specific timeframe. This will prevent bots from sending a large number of requests and overwhelming your API.

• Use CAPTCHA: Implementing CAPTCHA can prevent bots from accessing your API. CAPTCHA can help verify that the request is coming from a human and not a bot.

• User-Agent headers: You can filter requests based on user-agent headers. Most bots don't set a user-agent header, or they use a common user-agent. You can block requests that don't have a user-agent header or are using a common user-agent.

• API tokens: You can require that all requests to your API include a valid API token. This token can be used to authenticate the user and validate that they are authorized to access your API.

• Obfuscation: You can obfuscate the response from your API by encoding it in a format that is difficult for bots to understand. For example, you can encode your response in base64 or encrypt it.

It's important to note that none of these methods are foolproof, and determined attackers may still find ways to scrape your API. However, using a combination of these methods can significantly reduce the likelihood of successful scraping.

Q9. What do you mean by MEAN Stack?

MEAN stack is a popular open-source web development technology stack that consists of four main components:

• MongoDB: A NoSQL database that uses a document-oriented data model, which allows for flexible and scalable storage of data.

• Express.js: A server-side web framework for Node.js that provides a simple and flexible way to build web applications and APIs.

• Angular: A client-side framework for building dynamic and responsive single-page web applications.

• Node.js: A JavaScript runtime built on Chrome's V8 JavaScript engine that allows developers to build scalable, high-performance applications.

MEAN stack is known for its versatility and flexibility. It allows developers to use a single language (JavaScript) throughout the entire development process, from server-side to client-side. This makes it easier for developers to switch between different parts of the application, as they only need to know one language. Additionally, the MEAN stack provides a comprehensive set of tools and libraries, making it easier and faster to build complex web applications.

Q10. Do you know how to prevent a bot from scraping your publicly accessible API?

Yes, there are several ways to prevent bots from scraping your publicly accessible API:

• Implement authentication and access control: You can require authentication for access to your API, such as using OAuth or API keys. This can limit access to your API and track usage by individual users. You can also implement access control to limit the types of requests that can be made.

• Rate limiting: You can limit the number of requests that can be made to your API within a specific timeframe. This can prevent bots from sending a large number of requests and overwhelming your API.

• Use CAPTCHA: Implementing CAPTCHA can prevent bots from accessing your API. CAPTCHA can help verify that the request is coming from a human and not a bot.

• Use throttling: You can limit the number of requests that can be made by an IP address within a specific timeframe. This can prevent bots from making too many requests and reduce the impact of a DDoS attack.

• Obfuscation: You can obfuscate the response from your API by encoding it in a format that is difficult for bots to understand. For example, you can encode your response in base64 or encrypt it.

Q11. What makes MVC (Model View Controller) different from MVP (Model View Presenter)?

Both MVC (Model View Controller) and MVP (Model View Presenter) are design patterns used in software engineering to separate concerns and improve the maintainability and scalability of a codebase. However, there are some key differences between the two patterns:

• View and Presenter/Controller: In the MVC pattern, the View is responsible for displaying data to the user and receiving user input, while the Controller is responsible for handling user input, updating the Model, and updating the View. In contrast, in the MVP pattern, the Presenter is responsible for handling user input, updating the Model, and updating the View. The View is considered to be passive and is only responsible for displaying data.

• Testability: MVP pattern is more testable than the MVC pattern. This is because the Presenter is responsible for handling user input and updating the Model, which makes it easier to write unit tests for these components. In the MVC pattern, the Controller handles user input, making it more difficult to test.

• Complexity: MVC is considered to be a simpler pattern than MVP because it has fewer components. In contrast, MVP has more components, which can make it more complex to implement.

• Separation of concerns: MVP pattern enforces a stronger separation of concerns than MVC. In the MVP pattern, the View is passive and is only responsible for displaying data. The Presenter handles user input and updates the View and Model. This makes it easier to maintain and scale the codebase over time.

Source - Stack Overflow

Q12. What do you mean by Temporal Dead Zone in ES6?

The Temporal Dead Zone (TDZ) is a behaviour introduced in ECMAScript 2015 (ES6) that occurs when variables declared with the let and const keywords are accessed before they are initialized.

In ES6, variables declared with let and const are hoisted to the top of their block scope, but unlike variables declared with var, they are not initialized to a default value of undefined. Instead, they remain uninitialized until their declaration statement is reached during the execution of the code.

During the TDZ, accessing the value of an uninitialized variable will throw a Reference Error. This is because the variable exists in the scope, but its value is not yet initialized. The TDZ ends when the variable is assigned a value or when the block scope is exited.

For example:

In the example above, the variable x is declared with let, but it is accessed before it is initialized. This results in a Reference Error is thrown.

Q13. Why should arrow functions not be used in ES6?

Arrow functions are a powerful feature introduced in ES6 that provides a more concise syntax for defining functions in JavaScript. While there are some cases where arrow functions can be useful, there are also some situations where they should be avoided. Here are a few reasons why:

• No binding of this: Arrow functions do not bind their own value, instead inheriting this value of their parent scope. While this can be helpful in some cases, it can also be confusing and lead to unexpected behavior if the parent scope is not what you expect. In cases where you need to bind this to a specific object, a regular function may be a better choice.

• Cannot be used as constructors: Arrow functions cannot be used as constructors, meaning that they cannot be called with the new keyword to create new instances of an object. If you need to create instances of an object, you will need to use a regular function instead.

• No arguments object: Arrow functions do not have their own arguments object, which can be useful for functions that need to accept a variable number of arguments. If you need access to the arguments object, a regular function may be a better choice.

• Harder to debug: Arrow functions can make code harder to debug because they are anonymous and do not have a name property. This can make it harder to identify the function in stack traces and debuggers.

• Less readable: In some cases, the concise syntax of arrow functions can make code less readable, especially for longer functions or functions with complex logic.

It's important to note that arrow functions can be useful tools in the right situations. They can be helpful for writing shorter, more concise code and can help prevent issues with binding this to the wrong object. However, it's important to use them judiciously and be aware of their limitations.

Q14. What is event bubbling and capturing in JavaScript?

Event bubbling and capturing are two mechanisms used by the DOM (Document Object Model) in JavaScript to handle events on HTML elements.

When an event is triggered on an HTML element, such as a mouse click or a key press, the event first goes through the capturing phase. During this phase, the event is handled by the parent elements of the target element, starting from the outermost element and moving toward the target element.

After the capturing phase, the event enters the target phase, during which the event is handled by the target element itself.

Finally, the event enters the bubbling phase, during which the event is handled by the parent elements of the target element, starting from the target element and moving toward the outermost element.

This diagram illustrates the capturing and bubbling phases:

By default, most events use the bubbling phase to handle events, meaning that the event starts at the target element and moves up through its parent elements. However, it is possible to use the capturing phase instead by setting the capture option to true when registering the event listener.

Event bubbling and capturing can be useful for handling events on multiple elements at once or for selectively handling events on different elements based on their position in the DOM hierarchy. However, it is important to be aware of how event propagation works to avoid unexpected behaviour and improve the performance of event handling.

Q15. In the past, what was the best implementation or debugging you did?

I am trained in a vast corpus of data and have knowledge of various programming concepts and best practices that can be helpful in implementing and debugging code. If you have a specific question or problem related to programming, I would be happy to try to help you find a solution.

Q16. What is your experience with developing web applications?

I have been trained on a vast corpus of data related to web development and have knowledge of various programming languages, frameworks, and tools used in web development. If you have any specific questions related to web development, I would be happy to try to help you find a solution.

Q17. Explain the difference between client-side and server-side scripting.

Client-side scripting and server-side scripting are two different ways to handle code execution in web applications.

Client-side scripting refers to the process of running code on the client side, which is typically the user's web browser. Examples of client-side scripting languages include JavaScript, HTML, and CSS. Client-side scripts are executed by the web browser as the page is loaded or when an event occurs, such as a button click or form submission. Client-side scripting is primarily used to add interactivity and enhance the user experience of a web application.

Server-side scripting, on the other hand, refers to the process of running code on the server side, typically on a web server. Examples of server-side scripting languages include PHP, Python, Ruby, and Java. Server-side scripts are executed on the server side in response to a client request, such as when a user submits a form or clicks a link. Server-side scripting is used to generate dynamic content, interact with databases, and perform complex business logic.

Source - Tech Differences

Q18. What is AJAX, and how does it work?

AJAX stands for Asynchronous JavaScript and XML. It is a technique used in web development to create asynchronous web applications that can update parts of a web page without requiring a full page reload. AJAX allows web pages to load data from the server in the background and then update the page content dynamically without requiring a full page reload.

The key to AJAX is its ability to send HTTP requests asynchronously to the server using JavaScript without interfering with the user's interaction with the page. When a user interacts with a web page that uses AJAX, JavaScript sends an HTTP request to the server in the background. The server then processes the request and returns a response to the browser. JavaScript then receives the response and updates the page content dynamically without requiring a full page reload.

AJAX is used to create dynamic web applications that can provide a better user experience by allowing updates to occur without interrupting the user's interaction with the page. AJAX is commonly used in web applications to implement features such as auto-suggest search boxes, real-time chat applications, and infinite scrolling pages.

Q19. What are some techniques for improving website performance?

Improving website performance is crucial to enhance user experience and retaining visitors. Here are some techniques for improving website performance:

• Optimize images: Large images can slow down page load times. Optimizing images by compressing them and reducing their size can significantly improve page load times.

• Minimize HTTP requests: Minimizing the number of HTTP requests needed to load a web page can help reduce page load times. Combining multiple files into a single file and using CSS sprites can help reduce the number of HTTP requests.

• Use caching: Caching is a technique used to store frequently used data on the user's browser or server. Caching can help improve page load times by reducing the amount of data that needs to be transferred between the server and the user's browser.

• Minimize JavaScript and CSS: Large JavaScript and CSS files can slow down page load times. Minimizing these files by removing unnecessary code can help improve page load times.

• Use a content delivery network (CDN): A CDN is a network of servers that are distributed across the globe. Using a CDN can help improve page load times by serving content from a server that is closest to the user.

Q20. What are some common design patterns used in web development?

There are many design patterns used in web development, and the choice of pattern often depends on the specific needs and requirements of the project. However, here are some of the most common design patterns used in web development:

• Model-View-Controller (MVC) : This is a pattern that separates the application logic into three interconnected components: the model, which represents the data and business logic; the view, which represents the user interface; and the controller, which manages the communication between the model and the view.

• Single Page Application (SPA) : This is a pattern that allows for dynamic updates to a web page without requiring a full page reload. SPAs use JavaScript to dynamically update the content of the page based on user interactions without requiring a round trip to the server.

• Front Controller : This is a pattern where a central controller is used to handle all requests for a web application. The front controller receives all incoming requests, then routes them to the appropriate controller or handler.

• Dependency Injection : This is a pattern where the dependencies of an object are provided by an external source rather than being instantiated within the object itself. This allows for easier testing and maintenance of the code.

• Observer : This is a pattern where an object, known as the subject, maintains a list of its dependents, known as observers, and notifies them automatically of any state changes. This is commonly used in event-driven systems and user interface development.

These are just a few of the many design patterns used in web development. By understanding and using these patterns, developers can create more efficient, maintainable, and scalable web applications.

Q21. What is your experience with version control systems like Git?

Yes, Git is a very good version control system for managing changes to software code, as well as other types of files. There are several reasons why Git is so widely used and highly regarded:

• Distributed version control: Git is a distributed version control system, which means that every user has a complete copy of the repository on their local machine. This makes it easy for developers to work on their code offline, as well as collaborate with other team members on different branches of the code.

• Lightweight and fast: Git is designed to be lightweight and fast, with minimal overhead. This makes it a good choice for large projects with many contributors and files, where efficiency is important.

• Branching and merging: Git makes it easy to create and manage branches of code, which allows developers to experiment with new features or fixes without affecting the main codebase. Git also makes it easy to merge changes from different branches back into the main codebase.

• Open source: Git is an open-source project, which means that anyone can contribute to its development, and it is constantly improving and evolving as a result.

• Large community: Git has a large and active community of developers who provide support, documentation, and third-party tools and plugins to enhance its functionality.

Overall, Git is a powerful and versatile version control system that is widely used by developers and organizations around the world. Its features and benefits make it an excellent choice for managing software development projects of all sizes and complexity levels.

Q22. Explain the difference between synchronous and asynchronous programming.

Synchronous programming and asynchronous programming are two different approaches to executing code, and they differ in how they handle blocking operations and return values.

In synchronous programming, the code is executed sequentially, one statement at a time. When a function is called, the program waits for that function to complete and return a value before moving on to the next statement. This means that if a function takes a long time to complete, the entire program will be blocked and unresponsive until the function returns.

In contrast, asynchronous programming allows multiple tasks to be executed simultaneously without blocking the program. When an asynchronous function is called, it is scheduled to run in the background, and the program can continue executing other tasks without waiting for the function to complete. The asynchronous function may return a promise object, which can be used to handle the result of the function once it has been completed.

Asynchronous programming is particularly useful in situations where a program needs to handle multiple I/O operations or other time-consuming tasks. By using non-blocking I/O operations and call-backs, the program can continue to execute other tasks while waiting for the I/O operations to complete.

Q23. What is your experience with SQL and database management?

In my experience, I can tell you that SQL (Structured Query Language) is a programming language used for managing and manipulating data stored in relational database management systems (RDBMS). SQL is used for creating, modifying, and querying databases, as well as defining tables, views, and other database objects. It is a powerful and flexible language that can be used to perform complex data analysis, reporting, and manipulation.

Database management involves the design, implementation, and maintenance of databases, including tasks such as data modelling, database schema creation, indexing, backup and recovery, and performance tuning. Effective database management is critical for ensuring the accuracy, integrity, and security of data and for maximizing the performance and scalability of database systems.

There are several popular database management systems that use SQL, including MySQL, Oracle, Microsoft SQL Server, and PostgreSQL. Each of these systems has its own strengths and weaknesses, and the choice of the system often depends on factors such as performance requirements, scalability, security, and cost.

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To read the second part of this article on Full Stack Development interview questions Experienced level, please follow the link to Part 2. There, you will find an additional set of interview questions and answers to help you prepare for your Full Stack Development job interview. Good luck!

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