Top 40+ Full-stack Developer Interview Questions & Answers [2024]

I have listed 40+ Full-stack developer interview questions & answers that will help you get ready for this highly competitive job role. These interview questions have been carefully selected depending on what you will likely be asked in the interview. 

Reading this article can enhance your opportunities to crack your upcoming interview. This blog post is clear, concise, updated & easy to understand.

Start now!

Q1. What are data attributes?

Data attributes refer to the unique attributes of HTML that enable you to gather additional data on an element without influencing the styling or layout of the website. Data attributes are prefixed with data & are easily accessible with JavaScript. 

This is available in table format & refers to special attributes for elements in a programming language. These can gather user IDs, which can be manipulated with the help of JavaScript. 

Q2. What programming languages are highly preferred by full-stack developers?

Full-stack developers are highly interested in programming languages that enable them to work on both the back-end & front-end web applications. The highly preferred programming languages are JavaScript, HTML, CSS, PHP, Python, Java & Ruby. 

Also, some major back-end programming languages are C#, C++, Node.Js & more!

Q3. Can you name some popular full-stack developer tools?

A range of popular tools are used in full-stack development & they include:

• Webpack
• Git
• Python
• Bootstrap
• AngularJS
• SQL
• MongoDB
• Visual Studio Code
• GitHub
• Ruby on Rails
• Laravel
• JavaScript
• Nodejs
• Slack
• jQuery
• Backbone.js

Q4. Can you highlight some of the latest trends in full-stack development?

As per the industry professionals, candidates who are highly interested in cracking the full-stack developer interview questions must be aware of these latest industry changes. These trends are as follows:

• There is a rise in AI or artificial intelligence-based web solutions to automate processes & systems for higher performance. 
• No-code or Low-code development.
• Progressive web applications.
• AR (Augmented Reality) & VR (Virtual Reality) incorporation.
• Machine learning.
• Blockchain technology.

Q5. What do you mean by an application server?

An application server refers to the machine or tool that is responsible for hosting software applications. This specific tool manages business logic to create robust content by using different databases as well as various resources. 

It also offers a runtime environment to run application codes. Application server supports different types of APIs & Protocols. It also manages the communication between application logic, user interface & data storage layers of a web application. 

Q6. Explain the concept of multithreading & state its advantages.

Multithreading refers to the specific practice of dividing a process into multiple threads so that each thread can run independently using the same resources of the system. 

Some key advantages of multithreading are:

• Increased response time of the application as no thread is blocking others’ requests.
• Multithreading helps to reduce computing resources & apply them more efficiently.
• It uses less resources to run various processes simultaneously.
• It also boosts the overall user experience by breaking down into multiple threads and effectively works to save overall time without impacting the main flow of the application.

Q7. What do you mean by pair programming?

Pair programming is the practice of two web developers working on the same code together. Here, one developer writes the codes known as the driver & the other one, known as the navigator, reviews them for the smooth functioning of the website. 

The different perks you can get from pair programming cover the sharing of ideas, concepts, and knowledge for generating higher-quality code & quick problem-solving.

Q8. What are the different types of design patterns?

Design patterns are known as those standardized solutions that are very popular in software design issues. They offer design templates that solve particular design issues in different ways. 

Some popular design pattern types are:

• Behavioral patterns: These types of design patterns are focused on the interaction between different objects, such as command, observer & strategy. 
• Creational patterns: These specific types of design patterns deal with the object development mechanism.
• Structural patterns: These types of design patterns rely heavily on object & class composition. 

Q9. Can you explain some ways to reduce the load time of a web application?

There are some major ways to reduce the total load time of a web application, and those are;

• Image compression.
• Using a content delivery network (CDN).
• Allowing browser caching.
• Lazy loading implementation for videos & images.
• Minifying the JavaScript & CSS.
• Reducing the time of server response.
• A preferable hosting solution selection for performance optimization.

Q10. What is long polling?

Long polling refers to the specific web application development practice applied to push data from servers to clients as soon as they make a request for any data. Long polling helps developers boost the amount of information that is pushed from the server to clients. 

Long polling helps to keep requests & wait for more vital data to become highly available. Apart from this, long polling also helps to decrease the usage of bandwidth & latency as compared to regular polling and offers a better responsive experience. 

Q11. Why is Python a popular language choice for full-stack web developers?

Python is a popular programming language that is used widely by full-stack web developers for its multipurpose frameworks, fast processing, testing & complete development process management. 

It has an extensive ecosystem of frameworks & libraries that helps to simplify tasks such as database management, routing & authentication. It also offers huge database connectivity so that you can easily connect with popular databases like MySQL, Oracle & PostgreSQL. 

The multitasking capability of Python helps to simplify the debugging, deployment & prototyping process. 

Q12. What is unit testing & and what are its advantages?

Unit testing refers to the web development procedure in which the very little testable section of an application, known as units, is separately evaluated for proper web operation.

The key advantages of unit testing are:

• It helps web developers to write well-structured code, increasing the code quality.
• It helps simplify the debugging process by offering examples of code behavior.
• Unit testing also helps in the early detection of bugs, finding out the issues in the previous stage & decreasing the overall fixing costs. 
• It also helps in regression testing.

Q13. What do you mean by Box Model in CSS? State some major elements of the CSS Box Model.

The CSS Box Model refers to the box that includes each & every HTML element. It is the space that is occupied by an HTML element covering four essential elements. 

The four major elements of the CSS Box Model are content, margin, padding & border. They help in defining the web page layout. 

The “Content” refers to the original content of the box, whereas the “Border” refers to the edge around the padding, and the “Margin” is the specific space outside the border that separates the box from the other elements of a web application. The “Padding” is the Specific space between the border & the original web content. 

Q14. How is Hashtable different from HashMap?

Hashtable is synchronized and thread-safe, whereas HashMap is not synchronized and thread-safe. Hashtable does not support null keys or values, whereas HashMap supports null values or null keys. 

HashMap is a part of the frameworks of Java collection, whereas Hashtable is a part of the early Java framework. Hashtable is slower than HashMap because of synchronization, while Hashmaps are faster in single-threaded web applications. 

Q15. Explain the concept of double brace initialization & its advantages.

Double brace initialization refers to the method or process in Java that initializes an anonymous inner class into it. The first brace develops an anonymous inner class, while the second brace performs as an instance initializer. 

Some key advantages of double brace initialization are; 

• Develops inline initialization to make codes highly readable.
• Offers the best possible way to add initialization blocks to set up the collection or object state.
• It also enables the easy & quick initialization of collection for making a concise syntax. 
• Develops an anonymous inner class, which is very vital for making examples of abstract interfaces or classes. 

Q16. What do you mean by jQuery and state its features?

jQuery refers to the fast & lightweight JavaScript library that allows a user to apply JavaScript easily to their website. jQuery was developed based on the philosophy of “Write less, do more.”

It enables a developer to reduce the process of coding and save a lot of time. 

The significant features of jQuery are:

• HTML event methods.
• HTML/DOM manipulation.
• CSS manipulation.
• Animations & effects.
• Extensive library of Plugins.
• Cross-browser compatibility helps work with various types of web browsers. 
• AJAX assistance.

Q17. State the difference between MVP (Model View Presenter) & MVC (Model View Controller).

MVP & MVC are two major Android architecture patterns of a web application.

MVP or Model View Presenter refers to the architectural patterns that help compensate for some MVC issues. MVP is comprised of three major elements, and those are Model, view & presenter. 

On the other hand, MVC or Model View Controller helps to break down the code into three elements. As early as the web developers create a class for a web application, they should categorize it into one of the major three layers, including controller, model & view. 

In MVP, the unit testing process is supported, while in MVC, the unit testing process is limited. The major difference is that the controller has less power over the viewer; hence, it is difficult to unite the presentation logic using MVC.

Q18. Explain the concept of MEAN stack.

MEAN stack is the best tech stack among others due to its extensive applications covering cloud application development. MEAN stack is comprised of MongoDB, Epress.js, AngularJS & Node.js, which help a developer build robust & responsive web applications.

This end-to-end JavaScript stack is highly used for cloud applications. 

Q19. Can you explain the ways to optimize SQL queries?

Optimization of SQL queries refers to the identification of the most vital techniques or practices to boost the overall SQL query performance.

Below, I have mentioned some effective ways for SQL query optimization;

• Using indexes: Indexing columns are often used in JOIN conditions, WHERE clauses or ORDER BY elements can boost the execution of queries. 
• Avoid “SELECT” & choose “SELECT QUERY” instead to avoid unnecessary columns & reduce the speed of data loading.
• Always use the most suitable “JOIN” types for your specific SQL queries for desired outcomes & reduce the unnecessary loading time.
• Appropriate usage of “FETCH” & “LIMIT” can decrease unnecessary retrieval of vital information.
• Try to use specific tools such as EXPLAIN to get an idea & query execution optimization. 

Q20. What do you mean by “Strict Mode”? 

“Strict Mode” refers to the function in JavaScrip that enables a developer to execute the programming code in a specific setting. It supports the code errors that are generally executed without any other errors. 

You can allow a strict mode by including the “use strict” feature in the needed function or at the top of the file. “Strict mode” helps a developer to write secure codes. This mode can reduce some silent code errors by modifying them to throw errors. You can also limit some syntax that will be defined by future versions of ECMAScript.

Q21. How do you differentiate process & thread?

Process refers to an independent program of execution, whereas a thread refers to a specific segment of a process. Threads are generally lighter & need less amount of time for switching context, whereas processes are heavier as compared to threads & demand huge time for switching context. 

Threads require fewer resources as compared to processes & consume less amount of time to stop. Threads have various code segments, data segments & files, while the process has its own independent data segments & codes.

Q22. Explain the concept of data structure & state the different types of data structure.

Data structure refers to the specific way of data organization & storage in a unique format to recover the data effectively & very quickly. There are two primary types of data structure, and they include:

• Linear data structure: Array, Stack, Linked List, & Queue are some major types of linear data structures.
• Non-linear data structure: Graphs & Trees come under the category of Non-linear data structures. 

Array refers to a set of elements identified by an index; Stacks refers to Last In, First Out structure; queues refers to First In, Last Out structure; graphs are collections of vertices linked by edges; and Linked lists are components that are connected using pointers. 

Q23. What is a semantic HTML tag & why do you use it?

Semantic HTML refers to the markup in the HTML that defines the main purpose of a webpage rather than just presenting. For instance, features like footer, main, header, article, nav, p time & more are applied to address the various contents & sections of the web page.

The key reasons to use semantic HTML tags are;

• Semantic HTML helps search engines to estimate the content & significance of web pages. 
• It also manages a website, as the different codes are very easy to understand.
• It is vital for SEO or search engine optimization.

Q24. How is a web server different from a web application?

Web Server refers to the software that manages HTTP requests and serves web pages to give a better user experience. The common examples of web servers are Nginx & Apache.

On the other hand, a web application refers to an application that is easily accessible through a web browser, generally hosted on a web server. It incorporates both the back end, which is server-side logic & front end, which is the UI of the web application.

Web applications offer a runtime environment for enterprise applications, whereas web servers offer a runtime environment for web applications & web servers. 

Q25. Can you explain some popular methods of session management servlet?

There are some key methods of session management servlet & they are;

Hidden Form Fields: The incorporation of hidden fields in the forms helps manage the session state. 

Cookies: Cookies are information that a servlet forwards to the client’s browser. Cookies are saved by the browser & are sent again to the server with a new request.

URL Rewriting: A new session ID has been added to each URL, which is an aspect of this session management practice. The session ID is sent to the server by the browser to request a new web page. It allows the request to be linked to a specific session via the server.

HttpSession: Session data is saved on the server side through a built-in Servlet interface.

Q26. What are Meta tags & state their usage?

Meta tags refer to the piece of short information or tags that define the metadata on the HTML document. These tags always go into the inside part of the <head> element & generally used to define page description, author of a document, character set, viewport settings & keywords. 

The Meta tags are widely used in;

• SEO offers vital metadata for search engines.
• Character set that specifies the the encoding of characters.
• Viewpoint settings that control different layouts on mobile browsers. 

Q27. Can you explain the difference between Div tag & Span tag in HTML?

In HTML, Span Tags are generally utilized for paragraphs & inline elements, whereas Div tags are used for block-level elements. Span tags showcase any particular word, whereas Div tags usually showcase a specific section on a web page. 

With a Span tag, a developer applies a specific color code to highlight the HTML content, whereas developers incorporate borders with different widths & heights with specific color pixels to represent the HTML content.

Q28. What are CSS selectors?

CSS selectors are those specific patterns that are used to pick elements you want to style or design. These target HTML features rely on their class,  types, attributes, IDs &more.

Various popular CSS selectors are:

• CSS Universal Selector
• CSS Group Selector
• CSS Element Selector
• CSS Attribute Selector
• CSS Element Selector
• CSS Child Selectors
• CSS Pseudo Selectors
• CSS ID Selector

Q29. What is Flexbox & and what are its features?

The Flexbox in CSS is commonly known as a flexible box in a layout module. This helps to make flexible & responsive design layouts easily without adding any positioning & float. This is a major tool for designing responsive & flexible web layouts. 

The major features of Flexbox are:

• Order
• Responsive Design
• Space Distribution
• Alignment

Q30. What do you mean by callback function in JavaScript?

The callback function in JavaScript refers to the specific type of function that acts as a passing argument to another function. Despite the sequence through which these functions have been highlighted, they perform depending on functional calls.

Once the previous function has been completed, the next execution takes place. A developer can use a callback asynchronously or synchronously in JavaScript. 

Q31. What is Polyfill?

Polyfill refers to the piece of code that makes advanced HTML, CSS, or JavaScript elements in previous browsers that lack support. It is an effective way to change, edit, or add new features or functions.

In the majority of the cases, polyfill is generally written in JavaScript. 

Polyfills enable web developers to integrate an API irrespective of whether or not it is browser-supported. It allows developers to developers to use modern elements or functions in older browsers.

Q32. What is Hoisting & state its features?

Hoisting refers to the default behavior of JavaScript, where it moves declarations of a variable, class, or function to the top of the latest scope before the execution of the code. It enables a developer to use the functions or variables before declaration.

Some common & most popular features of Hoisting are:

• Let & Const declarations are not initialized but hoisted.
• Functions & variable declarations are hoisted.
• Variables that are declared with “var” have been initialized with “undefined.”

Q33. What is Promise in JavaScript?

Promise in JavaScript refers to the representation of the eventual failure or completion of an asynchronous function & its end value. It also enables asynchronous operations chaining by applying ‘.catch()’ & ‘.then()’ processes, boosting the error management & readability of codes.

When a unit of code does multiple asynchronous operations, promises in JavaScript may be a simpler & efficient process for the user to figure out.

The promises in JavaScript come in three different states, and those are Fulfilled, Pending, & Rejected. 

Q34. How do you differentiate between Git & GitHub?

Git refers to the shared version control system for monitoring modifications in source code at the time of software development. GitHub refers to the web-based platform that uses Git’s version control system. It also offers hosting for collaboration tools & software development, project management & tracking of issues. 

GitHub is an online SaaS service, while Git is a single piece of software. The Desktop interface offered by Git is called Git Gui, while GitHub desktop is its desktop interface. 

Q35. What is MongoDB?

MongoDB refers to the non-rational database of web applications. It is the type of document database that collects JSON-like documents. The most flexible model of MongoDB saves data that are usually unstructured & offers full indexing capabilities. 

It supports great functionality for big data sets, horizontal scaling via sharding & data schema-less data models.

Q36. Explain the concept of Git Stash.

Git Stash refers to the Git Command that keeps track of your unintentional modifications, stores them for later usage & then forwards them from your working copies. 

In order to stop a developer from making quick modifications while working on other development projects, Git Stash “stashes”—temporarily—modifications into your working directory. Apply git stash & then reapply the stashed changes some point later.

Q37. What is Entity Bean?

Entity Bean refers to the specific type of Enterprise JavaBean that helps to represent the persistent piece of data managed in a database. It is a server-side Java EE component. 

Entity Base manages database interaction, transaction management & lifecycle management. 

Q38. State the key features of MongoDB.

Some major features of MongoDB are;

• MongoDB offers Ad-hoc queries for real-time analysis & web application optimization. This supports various types of queries like regular expression queries and field & range queries. 
• It also offers Indexing so that a web developer can incorporate secondary & primary signals to index the area of a document saved in a MongoDB database.
• MongoDB also offers Schema flexibility, which helps collect the documents to make the structures different from each other. 

Q39. How do you differentiate responsive designs from adaptive designs?

Responsive web design refers to the specific approach where a page rearranges automatically according to the mentioned screen size, whereas adaptive web design is the specific web design where browsers load a layout designed particularly for the preferred platform.

Responsive designs use media queries & fluid grids, whereas adaptive designs use predefined layouts. Adaptive designs provide customized experiences for particular devices or screen sizes, whereas responsive designs are more flexible as compared to adaptive designs.

Q40. What is the difference between “Normalizing” & “Resetting”?

Normalizing is a modular method, whereas Resetting is a non-modular process. “Normalizing” refers to the different types of HTML style elements over browsers, while “resetting” refers to the collection of styles that is incorporated into the default HTML style elements. 

“Normalizing” is incapable of removing all the defaults, whereas “Resetting” helps in removing all the default layouts & stylings that are generally applied by browsers to page elements. 

“Normalize” supports debugging, whereas debugging is not that easy through “resetting.” 

Q41. What do you mean by tags, attributes & elements in HTML?

The HTML tags refer to the markup code that represents the content & structure of a webpage. An example of a tag for the paragraph is <p>.

An attribute is the element of a webpage that offers vital as well as additional data about an element. For example, ‘class= “text-center”>’. 

An element refers to the complete collection of content & tags like <p> This is a paragraph. </p>.

In summary, HTML tags represent elements, attributes help in modifying them & elements help to combine both the attributes & tags with content. 

Q42. What are Directives in Angular JS? How many types of directives are there in angular Js?

Directives refer to the classes that include additional behavior to the elements of Angular web applications. With the help of directives, a developer can apply CSS styles, manipulate DOM, and manage user inputs.

The four key types of directives in Angular.js include attribute directives, custom directives, structural directives & component directives. 

Q43. What do you mean by NPM or Node Package Manager?

NPM or Node Package Manager refers to a specific package managing tool for JavaScript. NPM is specially crafted to include modules as they are so that we can identify them whenever we search for nodes. Developers can reuse & share codes via NPM. 

With this, a developer can install, update & handle project dependencies. All Node Package Manager are referred to as package.json files. 

Q44. Can you name different datatypes available in PostgreSQL?

Different kinds of datatypes in PostgreSQL are:

• Boolean
• Geometric primitives
• Character types
• UUID
• XML
• Numeric types
• Temporal types
• Arbitrary precision numeric
• Arrays