Full Stack Developer Interview Questions and Answers

Top Full Stack Developer Interview Questions and Answers to Kill Your Next Tech Interview. Prepare the most important Full Stack Developer concepts, topics, and ideas you need to know to ace your interview. From front-end to back-end, servers and databases – everything you need to know is right here! So start your preparations today.

What is a full-stack developer?

A skilled designer and developer with experience in both client-side and server-side development.

Describe the MVC framework.

Model (data), View (user interface), Controller (actions) – a practice when writing software.

What function does Webpack serve?

A JavaScript/CSS/asset packaging and minification library for Pentaho.

Why should I avoid performing two-way data binding on the main thread in JavaScript?

Async operations prevent the solution from being unresponsive, that's why.

What exactly are WebSockets?

A communication mechanism that permits client-server interaction in real-time and bi-directional.

What distinguishes HTML from HTML5?

In HTML5, new elements like local storage, canvas, and semantic markups are added. And it is again faster/reliable, and mobile-friendly than its predecessor.

What is the difference between a class and an id in CSS?

An ID is a unique reference to each element, and a class only represents multiple references.

What is the Box Model in CSS?

That is, content, padding, border, and margin.

How to design a responsive website?

Responsible Layouts and Responsive Images: Using media queries, flexible grid systems, responsive images, and utilizing frameworks to their best potential.

What does semantic HTML mean?

We already have elements such as, and so on, that clearly express their meaning.

What does = stand for in JavaScript?

Only compares the value, whereas = compares both value and type (strict equality).

What does close mean in JavaScript?

A function that continues to store the variables of its containing lexical environment even after that parent function has completed.

What does event delegation mean?

Delegation by adding a single event listener to the parent element, listening for events arising from the child elements.

What exactly are promises?

Promises represent the eventual result of an asynchronous operation and can be in one of three states: pending, resolved, or rejected.

What's the difference between var, let, and const?

The var keyword is function-scoped, while let and const are block-scoped. The length of const can't be modified.

What exactly is virtual DOM?

It speeds up the performance by selecting a simplified copy of the DOM that collects updates together.

What exactly is JSX?

JSX (JavaScript XML) is a syntax extension that allows writing HTML directly within React.

Explain the state and props in React.

Props are "read-only" components data, state is mutable data that could be changed within the component.

What does useEffect do?

For performing side‐effects in functional components, i.e., retrieving data or system subscriptions.

What Is controlled component and the uncontrolled component? 

The difference between the above two cases is the creation of controlled components.

Controlled components depend on React to manage the form data; uncontrolled ones do not.

What does Node. js refer to?

A runtime that allows JavaScript to run server-side.

What does Express? js refer to?

A lightweight and adaptable Node. JS framework for creating APIs and web applications.

What are middleware functions in Express?

Functions that receive the request, response, and next middleware during the request-response cycle.

How to handle file upload in Node.js?

Utilizing libraries such as multer.

What does the process do? env serve in Node. js?

To retrieve environment variables.

What is the difference between SQL and NoSQL?

SQL is based on Schema and Relationships whereas NoSQL does not consider them in the system.

What does normalization mean?

Optimizing your data layout for both storage and data quality.

What is the indexing report for databases?

A data access accellerating performance enhancing method.

Explain how JOINs in SQL get executed?

JOIN operations combine rows from two or more tables, based on a related column between them.

What is MongoDB?

A NoSQL database with JSON-style documents that are a mix of adaptable, semi-structured schemas.

What is REST?

A bunch of stuff is available for building and developing web services that may work as they expand with HTTP operations.

What HTTP request methods are commonly used?

GET, POST, PUT, PATCH, DELETE.

What distinguishes PUT from PATCH?

PUT is a full replacement of the resource, while PATCH is less than that.

What do 200, 201, 400, 401, 403,404 and 500 status codes mean?

Respectively: OK, Created, Bad Request, Unauthorized, Forbidden, Not Found, and Server Error.

What is CORs?

Cross-Origin Resource Sharing - Let's you control what websites get to use resources on your server.

What distinguishes authentication from authorization?

Authentication is used to confirm identity, and authorization determines the rights of access.

What is JWT (JSON Web Token)?

An authentication technique using tokens for secure validation of information between distinct entities.

How can you save passwords securely in a database?

Through the use of libraries (e.g,. bcrypt) to hash.

What is OAuth2?

Method for permission granting , allowing applications to access protected user information and log in securely.

What distinguishes sessions from JWT?

Sessions store the information on the server, and JWT is stateless and contains user data within the token.

What are Docker and Kubernetes?

“Docker and Kubernetes are two of the best-known containers.” Docker is a platform used by developers to build containerized applications. These containers are lightweight and portable, and they are fully self-contained with all that is needed to run the application: libraries, system tools, as well as the code.

Kubernetes, as opposed to Doist (as you said, it is not a task list), is a container orchestration tool that automates packing and unpacking of applications such as Docker containers across multiple servers. It automates the tasks of deployment, scaling , and distributing load.

What are the steps to start a Node? app on a live server?

These by managing our processes, for instance, with PM2, or deploying on platforms such as Heroku / AWS / Vercel.

What is version control?

Dealing with source code changes using tools like Git.

What are Git branches?

Independent branches of the native code base are to be developed on their own or bug fixed.

What is unit testing?

Unit testing is a process in software development, or application evaluation, whichever view you prefer, of checking each piece of an application one by one to make sure that they work the way they're supposed to. This methodology focuses on the development of small and manageable parts, making it easy for a developer to identify and solve issues in the early stage. This improved the quality and reliability of the code.

What is integration testing?

Check how the modules or services interact.

What is end-to-end (E2E) testing?

Simulates real\-world user scenarios to test the complete system.

What are some tools you can use to test React applications?

Jest, React Testing Library, and Cypress.

What is mocking in tests?

Replacing the true functions with representations to study their dynamics