Top 50 Full-Stack Developer Interview Questions and Answers

Posted in

Top 50 Full-Stack Developer Interview Questions and Answers

Vinay Khatri
Last updated on May 22, 2024

    As technology is growing at a rapid pace, organizations are leveraging different sets of tools and technologies to develop software solutions. This resulted in a growing demand for full-stack developers.

    A full-stack developer is a professional capable of creating both the front-end and back-end of software applications. They possess a wide range of knowledge, including programming languages, tools, and technologies that make them flexible, adaptable, and agile. They serve as a great asset to organizations because they eliminate the need to hire separate front-end and back-end developers.

    The role of the full-stack developer is among the most popular and sought-after in the tech industry. Not only is it popular, but also financially rewarding. Full-stack developers receive attractive and sky-high salaries.

    Check out: Full-Stack Developer Salary

    So, if you aspire to have a career in full-stack development, your future is no doubt promising. As more and more companies are getting online and growing digital, you will find a myriad of job opportunities for full-stack developers.

    If you are appearing for a full-stack developer interview for the first time, it is obvious to get anxious. But there is nothing to worry about. We have put together a list of some frequently asked full-stack interview questions, along with answers. This list will undoubtedly help you ace your interview and become a full-stack developer.

    Before delving deep into our list of interview questions on full-stack development, we shall first throw light on some common roles and responsibilities of a full-stack developer.

    So, let us get started!

    Who is a Full-Stack Developer? What Do They Do?

    A full-stack developer is a professional specializing in both the front-end as well as back-end. They can develop both the client-side and server-side of software applications. They are versatile and all-rounders who have strong knowledge of all technologies involved in the development of complete web applications.

    When it comes to the front end, full-stack developers develop and design the front end of applications and work in collaboration with graphic designers to design elements. Regarding the back end, full-stack developers are in charge of creating APIs and RESTful services, testing and debugging software applications, ensuring cross-platform compatibility, and emphasizing security, scalability, and maintenance of applications.

    Moreover, full-stack developers possess knowledge of front-end and back-end technologies, including programming languages, frameworks, libraries, and other development tools. They always need to stay updated and learn new technologies to make themselves stand out from the crowd.

    What do Full-Stack Developers do?

    The following are some common roles and responsibilities of a full-stack developer in every organization:

    • Designing user interfaces for websites and web applications.
    • Developing the server-side of applications.
    • Testing and debugging applications to ensure they function as intended.
    • Creating applications that have responsive designs.
    • Developing APIs and RESTful services.
    • Ensuring the cross-platform compatibility of applications.
    • Optimizing software solutions by staying up with the latest technologies and trends.
    • Taking into account the security, scalability, and maintenance of software products while developing.

    Top 50 Full-Stack Developer Interview Questions and Answers for Freshers and Experienced [2022]

    We have categorized the list of full-stack interview questions into three levels: Basic, Intermediate, and Advanced. You can refer to the interview questions based on your level of experience.

    So, let us begin our list!

    Basic Full-Stack Developer Interview Questions

    1. What do you understand about full-stack development?

    Full-stack development entails end-to-end development of software applications, i.e., front-end as well as back-end aspects of applications. While the front end is concerned with designing interactive user interfaces, the back-end is all about developing business logic and making the front end operable.

    2. What skills do you need to become a full-stack developer?

    Full-stack developers are concerned with developing the client-side and server-side of software applications. As a result, they must be proficient in technologies involved in the front-end as well as back-end development.

    The following are the skills one must possess to become a full-stack developer:

    • Programming Languages: Front-end languages, like HTML, CSS, and JavaScript, and back-end languages, including Python, PHP, JavaScript, C++, Java, and Ruby.
    • Frameworks and Libraries: The front-end framework and libraries include React, Angular, jQuery, Bootstrap, Foundation, Materialize, Vue.js, and SASS. Meanwhile, back-end frameworks include Django, Ruby on Rails, Laravel, Spring, Express.js, and Ember.js.
    • Database: As full-stack developers manage the back-end of applications, it is necessary to possess hands-on experience working with popular database management systems. Some popular DBMS full-stack developers should be proficient in are MySQL , Oracle, MongoDB , and SQLite.
    • Popular Stacks: Hands-on experience working with at least one of the available stacks. These stacks include MERN, MEAN, LAMP, Django, and Ruby on Rails.
    • Web Servers: As a back-end developer, having knowledge of web servers is essential. Some popular web servers include Apache HTTP Server, NGINX, Lightttpd, and Microsoft Internet Information Services (IIS). Also, having a good grasp of Linux will help in administering servers.

    Some other additional skills include data structures and algorithms, operating systems, Linux commands , SSH , Character encoding, and Git.

    3. Which is the most preferred programming language by full-stack developers?

    Full-stack developers need to be proficient in multiple programming languages as they need to design the front-end as well as code the back-end of software applications. It is recommended for full-stack developers to gain mastery in at least two or three programming languages.

    For designing the front-end, full-stack developers must have a good grasp of HTML, CSS, and JavaScript. On the flip side, for the back-end, they can choose from PHP , Python, Java, Scala, Ruby, and C++.

    4. What do you know about pair programming?

    Pair programming is a technique in agile software development derived from Extreme Programming (XP), where two programmers work together on a single computer. It is a collaborative effort that entails a lot of communication. The primary aim of this technique is to facilitate communication between a driver and a navigator with the aim of proposing effective solutions or approaches to issues that may be pretty challenging for a single programmer.

    One programmer writes code while the other one reviews it. One who writes code is a driver, while the other who reviews the code line by line is a navigator. Furthermore, these programmers can switch their roles frequently. A driver can become a navigator or vice-versa.

    5. What are the advantages of pair programming?

    The following are the advantages of pair programming:

    • As pair programming involves two programmers, two brains are better than a single. If any of the programmers encounter a problem, there is always another one to help. For instance, if a driver encounters a problem, a navigator can think of a solution while the driver can continue writing code.
    • Detection of errors in code becomes easier because the navigator navigates through each line of code and comes up with all possible errors.
    • As both programmers work together, they get to learn many new things from each other by sharing their knowledge.
    • The driver and the navigator work together continuously for many hours. As a result, they constantly communicate with each other. This results in better communication skills.
    • This technique of software development results in improved code and high quality.

    6. Can you explain CORS?

    CORS is an acronym for Cross-Origin Resource Sharing. It is an HTTP-header-based mechanism to request a browser to allow a web application that is running at one origin (domain) to access the desired resources from a server present at a different origin.

    This mechanism enables scripts running on a client’s browser to access resources from and interact with other origins or domains. To put it simply, CORS is a browser mechanism that allows controlled access to resources outside of a given origin or domain.

    In CORS, a web page can include images, scripts, stylesheets, iframes, and videos from different origins. This mechanism provides a way for a browser and a server to interact with each other to determine whether allowing the cross-origin request is safe or not.

    CORS provides more functionality and freedom than the same-origin request. The same-origin policy does not allow access to resources from outside of the given domain.

    Consider a JavaScript application that needs to make a call to an Application Programming Interface (API) available on the other domain. The same-origin policy restricts the application to making the call, while the CORS policy allows the application to do so.

    7. List out some popular full-stack development tools.

    The following is a list of some popular full-stack development tools:

    • Backbone.js: This tool provides structure to your web applications. It is a web application framework that follows the model–view–controller (MVC) design architectural pattern.
    • CodePen: It is a development environment for front-end developers and designers. It is a social platform where people test and showcase user-created HTML, CSS, and JavaScript code snippets.
    • Visual Studio Code: It is an open-source source code editor for Windows, Linux, and macOS platforms. Some major features include syntax highlighting, debugging, code refactoring, and automatic code completion.
    • Slack: It is a professional messaging platform used especially for office work. Still, people use it for personal use.
    • GitHub: It is an internet hosting service for version control using Git. It hosts Git repositories.
    • WebStorm: It is a JavaScript IDE that facilitates the development of JavaScript applications by providing all essential developer tools under one roof.

    8. What do you understand by long polling?

    Long polling or HTTP long polling is a technique of sending or pushing information to a client as soon as it is available on a server. Therefore, there is no need for the server to wait for client requests. In this technique, once the server receives the request from the client, it does not close the connection. As a result, it responds only if it receives any new messages or reaches a certain timeout threshold.

    After the client receives the response from the server, it again sends a new request to the server. This results in a new pending connection to send data to the client, and the process repeats.

    9. What is continuous integration?

    Continuous integration (CI) is a DevOps software development practice that entails automating the integration of code changes from several developers into a single project. Developers frequently merge code to a central repository many times a day. Each integration then undergoes automated build and automated tests. In order to ensure the correctness of newly integrated code, automated tools come in handy.

    A version control system is a vital component of continuous integration. It is a software application that helps you keep track of changes made to the source code over time.

    The primary benefit of continuous integration is it detects and locates errors quickly and easily. In addition, it becomes easy to identify the change that caused an error in the code, as most changes are small. As a result, continuous integration reduces Mean Time to Resolution (MTTR). MTTR is the average time between an incident taking place to the incident being resolved completely.

    10. Explain multithreading.

    Multithreading refers to the ability of the central processing unit (CPU) to support the execution of multiple threads concurrently, where each thread is an independent unit of a process. In simple terms, multithreading is the execution of two or more segments of a computer program at the same time with the aim of utilizing the CPU to its fullest.

    The primary goal of multithreading is the maximum utilization of the CPU. It enables multiple threads of the process to run separately by sharing the process resources.


    • As threads are independent of each other, requests from one thread do not result in the blocking of requests from other threads.
    • If any of the threads in a process encounter an exception, there will be no effect of it on other threads.
    • Multithreading requires fewer resources than running multiple processes in parallel.
    • Creating and managing threads requires lower overhead, management, and time usage than process creation.

    11. How do GraphQL and REST differ from each other?

    GraphQL is a server-side technology for executing queries against existing data, whereas REST (REpresentational State Transfer) is a software architectural style with a set of constraints for designing and creating APIs and web services. The primary difference between GraphQL and REST is that the former is a query language or specification, and the latter is an architectural style.

    Let us discuss some more differences between GraphQL and REST below.



    It is a server-side technology for executing queries against existing data.

    It is an architectural style with a defined set of rules for creating web services and designing APIs.

    GraphQL follows client-driven architecture.

    REST follows server-driven architecture.

    It is organized in terms of a schema.

    It is organized in terms of endpoints.

    With GraphQL, you can send requests to APIs and retrieve the desired results by eliminating what you don’t want. It provides predictable results.

    The behavior of REST entirely depends on the URI and HTTP methods used. Therefore, it provides uncertainty about what to expect when calling an endpoint.

    With just a single request to an API with GraphQL, you can retrieve everything you need.

    When it comes to REST, you need to make multiple requests to get everything you want. This results in the prolonged response time of the server.

    GraphQL only supports the JSON format.

    REST supports multiple formats, including HTML, YML, XML and JSON .

    Mobile applications and microservices are the use cases of GraphQL.

    Simple applications and resource-driven applications are the use cases of REST.

    12. Explain dependency injection (DI).

    Dependency injection (DI) in software engineering is a design pattern in which an object or function receives other objects or functions on which it relies. It is used to implement inversion of control (IoC). It aims to create objects outside a class and provide those objects to the class in different ways. This makes it possible to move the creation and binding of objects outside the class that relies on them.

    Dependency injection entails three different types of classes, as follows:

    • Client class: It is a class that depends on the service class.
    • Service class: It provides the service to the client class.
    • Injector class: It injects the service class object into the client class.

    13. What do you understand about Inversion of Control (IoC)?

    Inversion of Control (IoC) is a design principle and pattern that entails inverting different types of controls in object-oriented design with the aim of achieving loose coupling. Here, controls refer to any responsibility of a class other than its primary one. This design principle emphasizes inverting control.

    To understand the concept of IoC, let us take a real-life example. Consider you have control over a car. As IoC is all about inverting the control, instead of driving the car yourself, you hire a cab where another person will drive it.

    14. How will you improve your website’s load time and performance?

    Here are the possible ways that we can implement to improve a website’s load time and performance.

    • Optimizing files and compressing images
    • Minimizing HTTP requests.
    • Utilizing content delivery networks and removing unused files and scripts.
    • Employing HTML5 and CSS3.
    • Minifying JavaScript and style sheets.
    • Optimizing caches.
    • Browser caching.

    15. What do you mean by polling?

    Polling is a method where a client requests the server for new data frequently. Shot polling and long polling are the two ways to implement polling.

    Intermediate Full-Stack Developer Interview Questions

    16. Explain the observer pattern.

    The observer pattern is a type of behavior pattern that is used when several objects are combined together in a one-to-many relationship. When there is a modification or update in one object, all other dependent objects get updated and notified automatically.

    There is an observer and subject in the observer pattern. The object is the observer that keeps an eye on the status of another object. The object is the subject that is being watched by the observer.

    The observer pattern provides coupling between the observer and objects and supports broadcast-type communication.

    17. What do you know about ‘use strict’?

    The ‘use strict’ is a directive introduced in the ECMAScript version 5. It defines that the JavaSCript code should run in strict mode. It is a literal expression and not a statement that all previous versions of JavaScript ignored. Due to ‘use strict’, you cannot take certain actions, and more exceptions are thrown.

    When you use ‘use strict’, the browser uses the strict mode, which is a more restricted and safer JS feature set. It helps you write clean code, and avoid the use of undeclared variables in a program. All modern browsers, such as Google Chrome, Safari, Firefox, and Opera, support ‘use strict’, except Internet Explorer 9 and lower versions.

    18. What are the advantages and disadvantages of ‘use strict’?

    Some worth-mentioning advantages of ‘use strict’ are as follows:

    • Even for common coding errors, the usage of ‘use strict’ throws exceptions.
    • It makes it easy to write secure JavaScript.
    • If you take any unsafe action within a program, it throws an error.
    • It does not support confusing or poorly thought-out features.
    • This mode takes any bad syntax as an error.

    The following are the disadvantages of ‘use strict’:

    • When using ‘use strict,’ you cannot access function.caller or function.arguments.
    • If you combine different scripts written in the strict mode, it results in a complex problem.

    19. What is the difference between GET and POST methods?

    The following table highlights the differences between GET and POST methods:





    This method is used to retrieve data from the server.

    This method is used to transmit data to the server.

    Post mechanism

    GET involves sending requests via a URL.

    POST involves sending requests through an HTTP request body.

    Data transmitting capacity

    It supports the transmission of limited data.

    The Post method supports the transmission of a large amount of data.

    Data type

    The GET method always sends data as text.

    This method sends any type of data.


    As GET is idempotent, it is safe.

    As POST is non-idempotent, it is not safe.

    Data visibility

    The data in transit is visible to users as it is included in a URL.

    The data in transit is not visible as it includes data in the message body.




    20. Explain MVC and MVP.

    MVC: It is an acronym for Model-View-Controller. It is an architectural design pattern that divides an application into three logical components: Model, View, and Controller. It keeps the business logic and the presentation of an application separate.

    The Model component is associated with all data-related logic that users work with. The view is concerned with displaying the model object inside the UI of an application. Finally, the controller acts as an interface between the model and view components.

    MVP: It is an acronym for Model-View-Presenter. It is derived from MVC and is primarily used for building user interfaces. Here, the Presenter acts as a middle person, like the Controller in MVC. It is responsible for maintaining actions or events between Model and View.

    21. How do MVC and MVP differ from each other?

    The primary difference between MVC and MVP is that the Controller in MVC does not pass data from Model to View. Instead, it simply notifies the View to take data from the Model. On the flip side, in MVP, the View and Model components are connected to each other. The Presenter receives data from the Model and transmits it to View to display to end users.

    22. What is Docker, and what are its uses?

    Docker is a containerization platform that packages software into a standard unit called a container. This container includes everything software needs to run regardless of the environment, such as libraries, code, system tools, operating systems, and runtime. Docker lets you build, test, run, and deploy applications quickly.

    For a working software to be deployed, the source code has to go through different platforms and environments, from the developer’s system to the production environment. As each of these environments is different, it becomes challenging to configure your software according to different environments.

    With Docker, you can streamline the process of development and deployment, as it provides a single consistent environment. The primary goal of Docker is to simplify the process of configuration.

    23. What do you understand about Node.js event loop?

    The event loop in Node.js supports asynchronous programming. Despite the fact that JavaScript is single-threaded, the event loop enables Node.js to perform non-blocking I/O operations. It does this by assigning operations to the operating system wherever and whenever possible.

    The following are the features of the event loop:

    • It is an endless loop. It waits for tasks, executes them, and sleeps until it receives more tasks.
    • This loop executes tasks from the event queue if and only if the call stack is empty.
    • It allows us to use callbacks and promises.
    • The event loop starts executing the oldest tasks first.

    24. What do you mean by promise?

    A promise is an object that is returned synchronously from an asynchronous function. It is capable of handling asynchronous operations. Also, it has a better capability to handle errors than callbacks. It provides a better way for readers to read code efficiently, particularly when the code performs multiple asynchronous operations. It can take any of the following three states:

    • Fulfilled: A promise is in the fulfilled state if it calls the onFulfilled() method.
    • Rejected: A promise is in the rejected state if it calls the onRejected() method.
    • Pending : A promise is in the pending state if it is not fulfilled or rejected.

    25. Name some common architectural patterns for building applications.

    The following are the common architectural patterns for building applications:

    • Model, View, Controller (MVC)
    • Model, View, Presenter (MVP)
    • Master-Slave Pattern
    • Monolithic architecture
    • Event-driven architecture
    • Layered pattern

    26. What is Semantic HTML?

    Semantic HTML or semantic markup is HTML that provides meaning to a web page and not just the presentation. For instance, the <p> tag represents that the text inside is considered a paragraph. As a result, it is both semantic and presentational. The readers understand which are the paragraphs, and browsers know how to and what to display as a paragraph.

    On the other hand, the tags <b> and <i> are not semantic as they do not provide any meaning to the text. Instead, it only specifies the font of the text or how the text should look (bold and italic).

    The following are examples of semantic HTML:

    • Header tags <h1> through <h6>
    • <blockquote>
    • <code>
    • <em>
    • <abbr>
    • <cite>

    27. Why should you use semantic HTML?

    Here are the reasons why you should use semantic HTML:

    • Semantic HTML provides additional information about the document, which improves communication.
    • It makes it more clear for browsers how to display the text, its meaning, and also the meaning of a web page.
    • Semantic HTML provides a description of the tags beyond how they should look on a web page.
    • As a web page becomes more clear and provides detailed information, search engines ensure that the right web pages are delivered to the right user queries.
    • It provides flexibility to style the content of web pages.

    28. Explain RESTful API?

    The REST API or RESTful API is an application programming interface that complies with the standards of the REST architectural style and enables interaction with the RESTful web services. Using RESTful APIs, we can create requests and receive responses through an HTTP request. It is also useful in mapping data from a cloud platform to a data warehouse and vice-versa.

    29. What is the MEAN stack?

    MEAN stands for MongoDB, Express.js, Angular, and Node.js. The MEAN stack is a free and open-source stack. It is a collection of JavaScript-based technologies for the development of web applications. JavaScript is the language that forms the basis for all these technologies. This stack is user-friendly for creating dynamic websites and web applications.

    MongoDB: It is a document-oriented database program. It is a NoSQL type of database program that uses JSON-like documents to store data in the form of key-value pairs.

    Express.js: It is a back-end web application framework for creating RESTful APIs using Node.js. It also supports developing web applications.

    AngularJS: It is an open-source front-end framework for creating desktop and mobile web applications.

    Node.js: It is a runtime environment for JavaScript. It enables developers to use JavaScript for the server-side development of applications. It makes it possible to run JavaScript code outside the browser.

    30. What is the MERN stack?

    MERN stands for MongoDB, Express.js, React, and Node.js. It is also a JavaScript-based web development stack. It is similar to the MEAN stack, but the only difference is it includes React instead of Angular.

    React is an open-source, front-end JavaScript-based library for creating user interfaces for web applications.

    31. What do you understand about a callback in JavaScript?

    A callback in JavaScript is a function that is passed as an argument to another function and is executed in the called function to accomplish the intended task or action. As these functions are dependent on each other, it gets pretty confusing with multiple callback functions. Hence, it is referred to as callback hell. You can use JavaScript callback functions synchronously or asynchronously.

    32. What is a connection leak in Java?

    A connection leak refers to a situation where some of the database transactions or requests are not committed, and they get abandoned and closed permanently. In simple terms, a connection leak is a situation where a connection is opened and is forgotten about.

    Java developers experience a connection lean when they work with the connection pool. If the connection pool has a part of code that fails to close a connection, the connection will leak from the pool whenever that part gets executed. If this continues, there will be a situation where the pool will run out of connection, which is termed pool exhaustion.

    You can fix the connection lean by closing connections properly and paying attention to the error handling code.

    33. How do you differentiate between fail-fast and fail-safe iterators?

    In Java, iterators are useful in iterating over Collection objects. If there is any structural modification in a Collection, the fail-fast iterator throws the ConcurrentModificationException. On the flip side, fail-safe iterators do not throw any exceptions even if there is a structural modification in the Collection.

    The following table describes the differences between fail-fast and fail-safe iterators:



    This iterator operates directly on the collection.

    This iterator operates on the cloned copy of the collection.

    It throws ConcurrentModificationException if there is a structural modification in the collection.

    It does not throw any exceptions.

    During the iteration process, there is no creation of a cloned object.

    It involves the creation of a cloned object.

    It consumes less memory during the process.

    This iterator requires more memory.

    Examples include HashMap, ArrayList, Vector, HashSet, etc.

    Examples of Fail-safe iterators include CopyOnWriteArrayList, ConcurrentHashMap, etc.

    34. How do null and undefined differ in JavaScript?

    Null: A variable is null when you assign a null value to it. This means it is an intentional absence of value. It is one of the primitive values in JavaScript. JavaScript will never assign a null value automatically. If we use null with the typeof operator, it provides the result as an object.

    Undefined: Undefined refers to the idea of declaring a variable but not assigning a value to it. It is a global object representing that the value does not exist in the compiler. When used with the typeof operator, it provides the result undefined.

    Let us understand null and undefined with an example.

    var var1 
    var var2 = null
    console.log(`var1 : ${var1}, type : ${typeof(var1)}`) 
    console.log(`var2 : ${var2}, type : ${typeof(var2)}`)


    var1 : undefined, type : undefined
    var2 : null, type : object

    In the above example, you can observe that we have not assigned any value to a variable var1. As a result, we get the output of var1 as undefined and its type as undefined. On the other hand, we have assigned a null value to var2. Therefore, in the output, you can see its type as the object.

    35. What is referential transparency in functional programming?

    In functional programming, referential transparency refers to the fact that an expression can be replaced by its equivalent value or anything having the same value without affecting the program’s output.

    To understand referential transparency better, we shall take one example.

    Consider that we have a function ten: val ten = add(5,5)

    If anywhere in your code, there is 10, you can replace it with the function ten, i.e., add (5,5). Here are some other equivalent expressions to the function ten that produce the same output:

    val twenty = ten + ten

    val twenty_v2 = add(5,5) + add(5,5)

    val twenty_v3 = 10 + add(5,5)

    val twenty_v4 = 20

    Advanced Full-Stack Developer Interview Questions

    36. What is the difference between normalization and denormalization?

    Here is a table that describes the differences between normalization and denormalization:



    Normalization is a method of dividing data into multiple tables with the aim of reducing data inconsistency and redundancy and achieving data integrity.

    Denormalization is in contrast to normalization, which includes combining data from multiple tables into a single table so that it becomes easy for querying.

    It is generally used in OLTP systems to make insert, update, and delete queries faster.

    It is used on OLAP systems to make searching and analysis quicker.

    Normalization emphasizes maintaining data integrity and removing duplicate data.

    It is hardly possible to maintain data integrity in denormalization.

    It results in an increased number of tables and joins.

    Denormalization reduces the number of tables and joins.

    It optimizes the use of disk space as there is no redundant data in databases.

    It results in the wastage of disk space as the same data is stored in different places.

    37. Explain blue/green deployment and rolling deployment.

    Blue/green deployment and rolling deployment are two deployment and release strategies that most organizations use in this modern era.

    Blue/green Deployment: This deployment strategy involves creating two different infrastructure environments, namely blue and green. The blue environment consists of old code, i.e., the old version, while the green environment comprises the latest code, i.e., the new version. There is only one live production environment at a time.

    Rolling Deployment: In this deployment strategy, new versions of code completely replace old versions, along with the infrastructure on which old versions run.

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

    The following table describes the differences between client-side and server-side scripting:

    Client-Side Scripting

    Server-Side Scripting

    It provides the requested output to users.

    The primary function of server-side scripting is to provide access to the required database as requested.

    It works in the front-end and is visible to end users.

    It works in the back-end and is not visible to end users.

    Client-side scripts run the user’s computer.

    Server-side scripts run on the web server.

    It does not provide the security of data.

    It provides the security of data.

    Client-side scripting involves HTML, CSS, and JavaScript.

    Server-side scripting includes PHP, Python, Java, and Ruby.

    39. How can you prevent a bot from scraping your publicly accessible API?

    It is not possible to prevent data scraping until the data in an API is accessible to the public. However, it is possible to prevent a bot from scraping publicly accessible API through rare limiting or throttling. A bot is an automated computer program on the internet to perform certain tasks.

    Rare limiting has the ability to prevent certain devices from making requests for a certain time. If a large number of requests are made, i.e., beyond the limits, a 429 Too Many Attempts HTTP error is raised. Make sure to record more than the IP address of devices, as IP addresses are not unique to devices, and hence, you can stop the whole network from accessing the API.

    40. Why should you not use arrow functions in ES6?

    The feature introduced in ES6 is an arrow function. It allows developers to write short and concise function syntax. It is a compact alternative to traditional function expressions. However, arrow functions come with a limitation in that they cannot be used in every use case. Here are some limitations of the arrow function:

    • There is no keyword.
    • It is not possible to use an arrow function as a method as it does not have bindings to ‘this' or 'super'.
    • It does not work well with the call, apply, and bind methods.
    • We cannot use it as a constructor.
    • An arrow function does not support the yield keyword in its body.

    41. Who do you know about event bubbling and event capturing in JavaScript?

    Event flow is a sequence or order in which a web page receives events. This process of event flow depends on three aspects, namely, event bubbling, event capturing, and event target.

    Event Bubbling: It comes in handy when developing a web page in JavaScript. It is used when event handlers are invoked when one element is nested into the other element where both elements are part of the same event. As a result, when you perform event flow, you need to use event bubbling. The calling takes place from the innermost elements and then propagates to the outermost.

    Event Capturing: Event capturing is the opposite of event bubbling. In event capturing, the event moves from the outermost element to the innermost.

    42. What do you mean by ACID in database systems?

    ACID refers to a set of properties that verifies that the process of transactions in databases takes place correctly. It stands for:

    A: Atomicity: It states that either an entire transaction takes place, or the transaction does take place at all. This means there is no partial execution of transactions.

    C: Consistency: It states that a database should be consistent, i.e., the integrity of data should be maintained, before as well as after the transaction takes place. It implies the correctness of the database.

    I: Isolation: This property states that multiple transactions in a database take place simultaneously without leaving the database in an inconsistent state. Every transaction executes without interrupting other transactions.

    D: Durability: After the execution of transactions, durability states that all the updates and modifications made to the database should be written to the disk and should persist even after the system failure takes place.

    43. Explain the temporal dead zone in ES6.

    Prior to ES6, we need to use the ‘var’ keyword to declare variables. With the introduction of ES6, there came ‘let’ and ‘const’. However, the declaration of ‘let’ and ‘const’ is block-scoped, i.e., they can be accessed only when enclosed within curly braces { }. Meanwhile, there is no such restriction for the ‘var’ keyword. Moreover, you cannot access ‘let’ and ‘const’ variables before assigning values to them, unlike ‘var’.

    The temporal dead zone refers to the time from which the execution of the block includes ‘let’ and ‘const’ variables to the initialization of those variables.

    44. Explain the SOLID principle in Java.

    Robert C. Martin or Uncle Bob has introduced the concept of the SOLID principle. SOLID has completely changed the world of object-oriented programming . It ensures that the software applications are modular and easy to understand, refactor, and debug.

    SOLID stands for:

    S: Single Responsibility Principle (SRP)

    O: Open-Closed Principle (OCP)

    L: Liskov Substitution Principle (LSP)

    I: Interface Segregation Principle (ISP)

    D: Dependency Inversion Principle (DIP)

    45. List out ways to handle exceptions in Spring MVC.

    Spring MVC is a Java framework for creating web applications. It provides the following ways to handle exceptions:

    • Controller-Based
    • Global Exception Handler
    • HandlerExceptionResolver

    46. What is a deadlock, and how to avoid it in Java?

    Deadlock is a situation where a set of processes gets blocked because each process holding a resource is waiting for other resources held by some other processes.

    The following are the different ways to avoid a deadlock in Java:

    • Avoid unnecessary locks: Make sure to use a lock on those members for which it is required. If you use locks unnecessarily on members, it may result in a deadlock. It is advisable to use a lock-free data structure.
    • Avoid nested locks: You must avoid providing locks to multiple threads if you have already provided a lock to one thread.
    • Use the Thread.join() method: A deadlock may occur if two threads are waiting for each other to finish. In such a situation, it is better to use join with the maximum time you want a thread to wait to finish.
    • Use lock ordering: Assign locks with numeric values. Make sure to acquire a lock with lower values and then move on to higher values.
    • Lock time-out: You can specify the time for a thread to acquire a lock. If it is not possible for a thread to acquire a lock, it must wait for a certain period of time before retrying to acquire a lock.

    47. How do you differentiate constructor injection from setter injection?

    The following table describes the differences between constructor injection and setter injection:

    Constructor Injection

    Setter Injection

    There is no partial injection of dependencies.

    There can be a partial injection of dependencies.

    It does not override the setter injection value.

    If you define both constructor and setter injection values, it overrides the constructor injection value.

    For any modification, it creates a new instance.

    It does not create a new instance for any changes.

    It makes bean class objects as immutable.

    It makes bean class objects mutable.

    48. What do you understand about a critical section?

    A critical section is a part of code in multi-threading where any thread can exclusively modify it. Semaphore or mutex is responsible for protecting the critical section. Using the Synchronized keyword and Reentrant Locks are the two ways of protecting the critical section in Java.

    49. What are the latest trends in full-stack development?

    Anyone who is passionate about becoming a full-stack developer should be aware of the following latest trends:

    • The rise in frameworks and libraries, such as React and Vue.js, real-time web applications, pregressive web apps, and mobile web development.
    • Improvements to JavaScript are advantageous for programming.
    • The inception of more compatible extensions.

    50. What do you understand about DevOps?

    DevOps is a set of tools, practices, and philosophies that automates and integrates the process between software development and IT operations. The primary objective of DevOps is to shorten the development cycle and provide continuous delivery with high quality. It primarily concentrates on cross-team communication, technology automation, and team empowerment.


    Becoming a full-stack developer is not a piece of cake. It requires a lot of skills and practice. With the right resources, proper guidance, and strong determination, you can surely become a full-stack developer. Along with technical skills, you also need strong software skills.

    With the above list of full-stack developer interview questions, you will be able to ace your next interview.

    Good luck!

    People are also reading:


    A full-stack developer is a professional capable of implementing the client-side (front-end) and server-side (back-end) of software applications.

    To become a full-stack developer, make sure to hold a bachelor’s degree in computer science or a related field, develop essential skills, practice to gain mastery in those skills, and earn certifications to demonstrate your skills.

    The most popular tech stack is MEAN, which stands for MongoDB, Express.js, Angular, and Node.js. This stack helps you build web applications.

    According to Glassdoor, full-stack developers in India earn an average salary of INR 7 lakhs per annum, whereas, in the United States, they earn $1 lakh per year.

    Unequivocally, full-stack development is a good career choice. It is one of the most promising, productive, and lucrative careers. There is an increase in the number of businesses going digital. This resulted in an increase in demand for full-stack developers. In addition, full-stack developers have a wide range of responsibilities in companies and need to possess a broad set of skills. As a result, they receive a handsome amount of salary.

    Leave a Comment on this Post