Full Stack Developer Interview Questions:

1. **Who is a Full-Stack Developer?**
   - A person who can develop both client and server software, mastering HTML, CSS, JavaScript for the browser, a server-side language, and database management.

2. **To develop a project from scratch, what technologies and languages would you need or what skills a full stack developer should have?**
   - Mastery in multiple programming languages (Java, Python, PHP, Ruby, C++), front-end technologies (HTML5, CSS3, JavaScript, jQuery, Angular, ReactJS), frameworks (Spring, Django, Hibernate), DBMS technologies (MySQL, MongoDB), design ability, server management (Apache, NGINX, Linux).

3. **Which language is the most preferred by full-stack developers?**
   - Proficiency in several languages, especially for front-end and back-end development, including Java, Python, Ruby, PHP, C++.

4. **Explain Pair Programming.**
   - Two programmers work together on one machine; one codes (driver), the other reviews (observer). Benefits include error reduction, improved code quality, and enhanced learning and collaboration.

5. **What do you mean by CORS (Cross-Origin Resource Sharing)?**
   - Allows web pages to access resources from other domains, extending flexibility beyond the Same-Origin Policy.

6. **What is Callback Hell?**
   - A situation with multiple nested asynchronous functions, leading to code that is hard to read and maintain.

7. **Explain Long Polling.**
   - A technique where the server holds a client request open until new data is available, enhancing real-time data flow.

8. **Can you tell me what are the latest trends in Full Stack Development? Also, how do you keep yourself updated about the new trends in the industry?**
   - Emphasis on frameworks and libraries (ReactJs, VueJs), progressive and real-time web apps, mobile web development, and JavaScript enhancements.

9. **State difference between GraphQL and REST (Representational State Transfer).**
   - GraphQL offers declarative data fetching and precise data retrieval, whereas REST is an architectural style for APIs with less predictability in data retrieval.

10. **What is CI (Continuous Integration)?**
    - Automating the integration of code changes into a repository, facilitating rapid error detection and reducing Mean Time to Resolution (MTTR).

11. **Explain the meaning of multithreading.**
    - Running multiple threads simultaneously within a process, improving resource utilization and application responsiveness.

12. **Explain the benefits and drawbacks of using "use strict".**
    - Enforces stricter parsing and error handling in JavaScript, preventing common coding mistakes and unsafe actions.

13. **What are some of the uses of Docker?**
    - Isolates applications from their environment, simplifying configuration and consistency across different machines and platforms.

14. **Explain event loop in Node.js.**
    - Manages asynchronous operations, allowing non-blocking execution and handling of multiple operations concurrently.

15. **Is there a way to decrease the load time of a web application?**
    - Techniques include image optimization, external JavaScript and CSS files, reducing redirects, asynchronous file loading, and minifying HTML, CSS, and JavaScript.

16. **Explain dependency injection.**
    - A design pattern where a class receives its dependencies from external sources rather than creating them internally, enhancing modularity and testability.

17. **What do you mean by observer pattern?**
    - A design pattern where an object (subject) notifies a list of observers about changes, facilitating one-to-many dependency relationships.

18. **State difference between blue/green deployment and rolling deployment.**
    - Blue/Green involves switching between two environments, whereas Rolling Deployment gradually replaces old versions with new ones across all nodes.

19. **Explain inversion of control.**
    - A principle where custom-written portions of a program receive the flow of control from a generic framework, promoting loose coupling.

20. **What do you mean by referential transparency in functional programming?**
    - An expression is considered referentially transparent if it can be replaced with its computed value without changing the program’s behavior.

21. **State difference between normalization and denormalization.**
    - Normalization reduces redundancy and improves data integrity by organizing data into tables. Denormalization merges tables to speed up query performance but may introduce redundancy.

22. **In Java, what is a connection leak? How can you fix this?**
    - Occurs when a database connection is not properly closed, potentially leading to resource exhaustion. Prevented by ensuring connections are closed after use.

23. **What is Promise and explain its states?**
    - Represents the eventual completion (or failure) of an asynchronous operation and its resulting value. States are Pending, Fulfilled, and Rejected.

24. **State the difference between GET and POST.**
    - GET requests data from a resource, adding data to the URL, while POST sends data to be processed, with no data displayed in the URL.

25. **Explain the Restful API and write its usage.**
    - Utilizes HTTP requests to perform operations on data, adhering to REST principles for scalable and stateless communication.

26. **What do you mean by MEAN Stack?**
    - Stands for MongoDB, ExpressJS, AngularJS, and Node.js, a stack of JavaScript-based technologies for developing web applications.

27. **Do you know how to prevent a bot from scraping your publicly accessible API?**
    - Implementing throttling or rate limiting to minimize bot activity, though completely preventing scraping is challenging.

28. **What makes MVC (Model View Controller) different from MVP (Model View Presenter)?**
    - MVC divides an application into three interconnected parts, while MVP enhances testability and separation of concerns with a presenter handling the UI logic.

29. **What do you mean by Temporal Dead Zone in ES6?**
    - The period between entering the scope where a variable is declared and its actual declaration and initialization, where accessing variables prematurely throws an error.

30. **Why should arrow functions not be used in ES6?**
    - They lack bindings to 'this' or 'super', making them unsuitable for methods, constructors, or functions requiring dynamic context.