Top Full Stack Developer Interview Questions and Answers

Ready to get a job as a full-stack developer? Worried about your interview? It's natural to be nervous about interviews, especially for first timers. In current times, there is a huge demand for full-stack developers. It is one of the highest-paying jobs as of now

Full-stack developers are known to manage both front end and back end development. They have a wide range of skills and the necessary expertise to fully develop websites.

Since the average salary for a full-stack developer is quite high, organizations tend to follow a very stringent recruitment process while hiring a full-stack developer. When you are well-prepared and know your concepts well, you can crack the interview easily.

In this blog, we have discussed the top full-stack developer interview questions job applicants and candidates are asked during their interviews.

Top full-stack developer questions and answers

What is full-stack development?

Full-stack development is concerned with the all-around development of a website or web application. Both the front end and back end are developed simultaneously. The process has three parts:

The front end that handles user experience is developed using HTML and JavaScript.
The back end (server side of the website) is developed using languages such as Python and Java.
The database layer

What does a full-stack developer do?

Full-stack developers have the knowledge to develop an entire web application/website. They are skilled in both front-end and back-end technologies and can develop both server and client software. They are familiar with programming databases, browsers, and servers. They are experts in using CSS, HTML, Java and Python.

Which technologies and languages does a full-stack developer need to know to do a project from the beginning?

To develop a project from the beginning, a full-stack developer needs to have the knowledge of the following:

Front end technologies: CSS3, Angular, Ajax, HTML5 and jQuery are some of the front end technologies.
Programming languages: Python, Java, C++ and Ruby are some of the many programming languages on which code is written. Full-stack developers should know the way to design and maintain the project as per the language they code on.
Frameworks: Full-stack developers must be skilled in P HP , Spring Boot, Spring and Django, to name a few frameworks.
Databases: They should have knowledge of at least one database. Knowledge of multiple databases such as SQLite, MySQL and Oracle is beneficial.
Server: Full-stack developers must be familiar with Linux and Apache servers.
Design Ability: Knowledge of UI/UX and good design ability is also integral for full-stack developers.
Additional Skills: Knowledge of Git, Linux command, character encoding, and machine learning is also beneficial.

Importance of Full-Stack Developers

Full-stack developers are all-rounders. They have knowledge of all elements of software development and are skilled in multiple technologies. There are more chances for software development to function smoothly, efficiently, and quickly. Chances of miscommunication are fewer. Full-stack developers can easily communicate with project managers and IT departments.

What is Pair Programming? What Are Its Advantages?

As the name suggests, pair programming involves two programmers working at the same workstation. Both programmers have different duties. One works as a driver (writing the code) and the other works as a navigator/observer (views and checks every line of the code). The programmers typically switch their roles at any time. There are three possible pairings in this situation - newbie with newbie, expert with newbie, and expert with expert.

Pros of pair programming include the following:

Pair programming can yield significant results and leads to more productivity and learning.
There are fewer chances of errors in coding.
It develops communication and collaboration between team members.
It can also lead to breakthroughs since two people working at the same thing are better than one.

Must Read: How to Become a Full-Stack Developer: Step By Step Guide

What is IoC?

Inversion of Control, also called IoC, is a principle of software engineering used to make classes loosely coupled. Using IoC makes classes easy to maintain and test. It primarily means that the control and dependencies of the objects are transferred to a framework from the main program.

What is CORS?

Cross-Origin Resource Sharing, or CORS, enables a browser in a domain to make cross-domain requests. This means a domain can request resources from another domain but only restricted resources can be requested. CORS helps provide some flexibility to the same-origin policy.

What is Callback Hell?

Also called Pyramid of Doom, Callback Hell is a slang term used in asynchronous JavaScript. This typically happens because of the difficulty level of asynchronous JavaScript and poor coding practices. In essence, callback hell happens when there are many asynchronous functions and since they are interdependent, they can get messy.

What are MVC and MVP? What do they offer?

MVC and MVP are architectural patterns. They are used while designing a website. Model View Controller, or MVC, helps develop Java Enterprise Applications. It gets its name from the fact that it divides an application into three parts: model, view, and controller. All three parts have separate functions.

Model View Presenter, on the other hand, comes from MVC. In this pattern, view and controller are divided into view and presenter. The role that the controller performs in MVC is performed by the presenter in MVP.

Some of the differences between MVC and MVP are as follows.

Basis	MVC	MVP
Coupling	View and model are tightly coupled	View and model are loosely coupled
Communication	The view and controller layer are in the same fragment here.	An interface manages the communication between the view-presenter and presenter-model
User Input	Controller handles user inputs	View handles the user inputs
Relation Type	Many-to-one (between controller and view)	One-to-one (between presenter and view)
Primary Component	Controller	View
Unit Testing	Limited Support	Well-Supported

What is Dependency Injection?

Dependency injection is useful as it provides/injects objects with their dependencies. It is a design pattern that ensures that objects don't have to construct them. A dependency can be injected through a setter or constructor injection. It has the following types of classes:

Client class (dependent on service class)
Service class (useful to the client class)
Injector class (used to inject objects of service class into client class)

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How Can We Enhance A Website’s Scalability and Performance?

There are many ways to enhance a website’s efficiency and increase its scalability. Some of them include the following:

Avoid URL redirects and duplicate codes
Reduce DNS lookup
Avoid unnecessary images, CSS, and Inline JavaScripts
Use srcset for responsive images
Optimize caches
Browser caching
Optimize files
Compress images
Minimize HTTP requests

Explain the Differences Between Get and Post Requests

Get and Post have many significant differences. Let us discuss some of them.

Basis	Get	Post
Purpose	The purpose of a Get request is to get data from the server	Post request sends data to the server
Data Type	Text	Any type
Post Mechanism	URL	HTTP request body
Security	Get is safe as it is idempotent	Post is non-idempotent and thus unsafe
Efficiency Level	More efficient	Less efficient
Capacity	Only limited data can be sent	Large amount of data can be sent
Visibility Level	Visible to the user	Not visible
Stored	Get requests are stored in browser history	These requests are not stored
Bookmarking	Get request can be bookmarked in the browser	Post requests cannot be bookmarked

What are the differences between GraphQL and REST?

GraphQL and REST have many differences. Some of them include the following:

Basis	GraphQL	REST
Meaning	This is a query language for APIs that gives clients the ability to retrieve data from the API	This is an architectural style and is used to define constraints while creating web services
Architecture Type	Client-driven architecture	Server-driven architecture
Organized in	Terms of Schema	Terms of Endpoints
Development Speed	Fast	Slow
Resource Determination	Server determines the availability of resources	Server determines shape and size of resources
Consistency	High consistency in all platforms	Low consistency level
Supported Format	JSON	XML, HTML, JSON, and many others
Use Cases	Mobile applications and microservices	Simple and resource-driven applications
Message Format	String	Anything
Learning Curve	Difficult	Moderate

What is CI and what are its advantages?

Continuous integration, called CI, is a practice under which developers merge their code changes many times a day into a shared repository. This enables them to find problems and solve them early. Software development is a long and time-consuming task and CI helps make it faster and less risky.

Some of the advantages of CI are as follows:

Allows early feedback and better transparency
Problems can be identified early
Gives users a better experience
Costs are reduced due to automated testing
Reduces mean time to resolution (MTTR)

What is CD? How is it different from CI?

Continuous delivery, or CD, is a practice in which changes in the code are built, tested, and deployed to production automatically. This enables fast and easy release of the software.

The differences between CD and CI are as follows:

Basis	Continuous Integration	Continuous Delivery
Focus	Automation testing ensures software is bug-free	Releasing latest changes in the software
Performed	CI happens when developer checks-in	Changes in the code are continuously delivered
Aim	Detect and resolve issues earlier	Provide software updates quickly
Test Usage	Uses unit tests	Uses business logic tests

What is Multi-threading? What are its Advantages?

Multi-threading allows more than one user to simultaneously run the same program. It is the application/operating system’s way of multi-tasking. This ability also allows the program to handle multiple requests from one user at the same time.

Some of the benefits of multi-threading are as follows:

System resource usage is minimized
Server responsiveness is improved
Any issue in one thread does not affect the working of other threads
Processes share resources
Increases scalability
Enables better inter-process communication

What is the RESTful API?

RESTful (representational state transfer) API is an architectural style that allows developers to create HTTP requests and receive responses.

What are the differences between abstract and interface?

Some of the differences between abstract and interface are as follows.

Basis	Abstract	Interface
Methods	Abstract and non-abstract methods	Only abstract methods
Variables	Static, non-static, final, and non-final variables	Only static and final variables
Implementation	Can implement interface	Cannot implement abstract class
Extension	Can be extended by using ‘extends’	Can be implemented using ‘implements’
Multiple inheritance support	Doesn’t support multiple inheritances	Support multiple inheritances
Types of class members	Can have several class members, such as private and protected	Can only have public members

What Are the Different Types of Design Patterns?

There are primarily three types of design patterns. They are as follows:

Creational: These design patterns are about the creation of an object. They can be further divided into object-creational and class-creational patterns.
Structural: These involve arranging objects and classes for new and larger functionality.
Behavioral: These help in detecting common patterns used by objects to communicate.

How Can You Decrease An Application’s Load Time?

There are many ways to decrease the load time of an application. These include the following:

Optimise the images by shifting to a different file format
Place CSS and JavaScript in external files
Avoid redirects on the website
Ensure that your CSS and JavaScript files load asynchronously

What are the Common Architectural Designs Used for Designing Applications?

The following architectural designs are commonly used:

Model View Controller
Master-Slave
Event-Driven
Monolithic
Model View Presenter
Layered

What Are the States of Promise?

Just like Callbacks, states of promise handle asynchronous operations. However, promises are much better at handling errors and reading codes. There are three states of promise:

Pending: Initial state of promise
Fulfilled: Indicates a successful operation
Rejected: Indicates a failed operation

What is ACID?

ACID is an acronym for Atomicity, Consistency, Isolation, and Durability. It is used in database systems and is a set of properties that enable the reliable processing of transactions in the database.

What is Referential Transparency?

Referential transparency refers to replacing an expression while ensuring that the final result of the program remains unchanged. The key is that the program's behavior stays unchanged regardless of whether an actual value or reference value is used.

The ones discussed above are some of the top full-stack developer interview questions and answers asked from candidates striving for careers in full-stack development. These will help you prepare for your interview. An interview can be a tricky experience when you don’t have good communication skills to express your knowledge. So, focus on developing your interpersonal skills as well while preparing your technical knowledge.

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