200+ Full Stack Software Developer Interview Questions and Answers

Questions asked in a Full Stack Software Developer interview

• Questions on OOPs concepts, design patterns, and MVC architecture

• Array and string manipulation in Java

• Understanding of JDK, JRE, and JVM

• Usage of 'this' and 'super' keywords

• Solving Java problems like palindrome, prime number, etc.

• Explanation of Java's platform independence

• SQL queries and commands

Process to find root cause of slow application for database, backend api and frontend side.

• Check server logs for errors and warnings

• Use profiling tools to identify bottlenecks

• Optimize database queries and indexes

• Minimize network requests and optimize API responses

• Reduce image and file sizes for faster loading

• Use caching to reduce server load

• Check for memory leaks and optimize memory usage

An array linked list can be executed using a loop to traverse through the array and access the linked nodes.

• Create an array to store the linked nodes

• Assign the first node to the first element of the array

• Use a loop to traverse through the array and access the linked nodes

• To access the next node, use the index of the current node as the index of the next node in the array

• Stop the loop when the last node is reached

Linking stylesheet with HTML is done using the link tag in the head section of HTML.

• Use the link tag with rel attribute set to stylesheet and href attribute set to the path of the stylesheet file.

• Place the link tag inside the head section of the HTML document.

• Example:

Streams in C++ are used for input and output operations. Predefined streams in C++ include cin, cout, cerr, and clog.

• Streams in C++ are objects that allow reading from or writing to external sources or destinations.

• cin is the standard input stream used for reading input from the user.

• cout is the standard output stream used for printing output to the console.

• cerr is the standard error stream used for printing error messages to the console.

• clog is an alternative to cerr for pri...read more

Reference variables in C++ are aliases for other variables, allowing direct access and manipulation of the original data.

• Reference variables are declared using an ampersand (&) symbol.

• They must be initialized when declared and cannot be reassigned to refer to a different variable.

• Changes made to a reference variable affect the original variable it refers to.

• They are commonly used to pass variables by reference to functions.

• Reference variables can be used to create multiple na...read more

Scope rules in C++ determine the visibility and accessibility of variables and functions within a program.

• Variables declared within a block have local scope and are only accessible within that block.

• Global variables have file scope and can be accessed from any function within the file.

• Function parameters have function scope and are only accessible within that function.

• Nested blocks can have their own scope, and variables declared within them are only accessible within that bl...read more

Semaphore and monitor are synchronization tools used in concurrent programming.

• Semaphore is a signaling mechanism that allows multiple threads to access a shared resource simultaneously.

• Monitor is a synchronization construct that allows threads to have both mutual exclusion and the ability to wait (block) for a certain condition to become true.

• Semaphore is a lower-level primitive, while monitor is a higher-level abstraction.

• Semaphore can be used to implement a monitor.

• Example...read more

Yes, a service file can have more than one instance by creating multiple instances of the service class.

• Multiple instances of a service class can be created by instantiating the class multiple times.

• Each instance will have its own state and can be used independently.

• This can be useful for scenarios where multiple instances of the same service are needed to handle different tasks.

BCNF is not necessarily better than 2NF & 3NF, it depends on the specific requirements of the database.

• BCNF is the highest normal form and ensures that there are no non-trivial functional dependencies between any subset of candidate keys.

• 2NF and 3NF are also important and should be used when appropriate.

• For example, if a database has a composite primary key and non-key attributes that depend on only one part of the key, 2NF should be used.

• If a database has transitive dependen...read more

JavaScript is a versatile programming language that can be used for both front-end and back-end development.

• JavaScript is primarily used for client-side scripting, allowing dynamic content and interactivity on websites.

• It can also be used for server-side development with frameworks like Node.js.

• JavaScript has a wide range of capabilities, including manipulating HTML and CSS, handling events, creating animations, and making HTTP requests.

• It supports object-oriented programming...read more

rand() generates a random number, srand() seeds the random number generator.

• rand() generates a pseudo-random number between 0 and RAND_MAX

• srand() sets the seed for the random number generator used by rand()

• srand() should be called before rand() to ensure different sequences of random numbers

• Example: srand(time(NULL)) sets the seed to the current time, ensuring a different sequence each time the program is run

Program to return list of .tst files in given directory and subdirectories

• Use recursion to traverse through all directories and subdirectories

• Check if each file has .tst extension and add to list if true

• Use built-in functions like os.listdir() and os.path.splitext() in Python

Class based vs function based React components with differences explained.

• Class based components are ES6 classes that extend React.Component and have lifecycle methods.

• Function based components are simple functions that return JSX.

• Class based components have state and lifecycle methods, while function based components use hooks for state and lifecycle management.

• Class based components have a render method, while function based components directly return JSX.

• Class based compon...read more

Top-n analysis is a technique used in DBMS to retrieve the top n records based on a specific criteria.

• Used to retrieve top n records

• Based on specific criteria

• Commonly used in data analysis and reporting

No, you will not see 2 objects in the set. To insert unique objects to a set, you can override the equals() and hashCode() methods in the object class.

• In a set, each element must be unique based on the equals() method. If you add 2 objects with the same attribute values, only one will be stored in the set.

• To ensure uniqueness, override the equals() and hashCode() methods in the object class. This will define how objects are compared and stored in the set.

• For example, if you h...read more

Character constants are fixed values represented by a single character in C++.

• They are enclosed in single quotes (' ')

• Examples include 'a', 'B', '5', '$'

• They are also known as character literals

Normalisation is the process of organizing data in a database to reduce redundancy and improve data integrity.

• It involves breaking down a table into smaller tables and defining relationships between them.

• Normalization helps to eliminate data inconsistencies and anomalies.

• There are different levels of normalization, with each level having specific rules to follow.

• Examples of normalization include converting repeating groups into separate tables and creating a junction table fo...read more

The new Angular feature that doesn't use @NgModule is called Ivy.

• Ivy is the new rendering engine in Angular that doesn't rely on @NgModule for compilation.

• It allows for faster compilation times and smaller bundle sizes.

• Ivy enables features like improved tree shaking and better debugging capabilities.

• Example: Angular 9 introduced Ivy as the default rendering engine.

In the DropBox assignment, we can enhance security by implementing two-factor authentication, role-based access control, and encryption.

• Implement two-factor authentication to add an extra layer of security

• Utilize role-based access control to restrict access based on user roles

• Implement encryption to protect data both in transit and at rest

INDEX is generally created on columns that are frequently used in WHERE, JOIN, and ORDER BY clauses.

• INDEX improves the performance of SELECT queries.

• INDEX should be created on columns with high selectivity.

• INDEX should not be created on columns with low selectivity.

• Examples of columns to create INDEX on are primary keys, foreign keys, and columns used in search queries.

The application would not work properly without @NgModule as it is required to bootstrap the application and configure dependencies.

• Without @NgModule, the application would not be able to bootstrap and start properly.

• NgModule is used to configure dependencies, such as components, directives, and services.

• NgModule also helps in organizing the application into modules for better maintainability and reusability.

The process to sign legal documents involves reviewing the document, signing in the presence of a witness if required, and storing the signed document securely.

• Review the legal document thoroughly to ensure understanding of its contents and implications

• Sign the document in the designated signature area using your legal name

• If required, have a witness present during the signing process

• Store the signed document in a secure location for future reference

JavaScript is a programming language used for web development, while Node.js is a runtime environment for executing JavaScript code outside of a web browser.

• JavaScript is primarily used for client-side scripting, while Node.js is used for server-side scripting.

• JavaScript is executed in a web browser, while Node.js is executed on a server.

• Node.js provides additional modules and libraries for server-side development, such as file system access and networking capabilities.

• JavaSc...read more

Questions on Java vs JavaScript, Linux commands, Jquery, and JS communication with serverside.

• Java is a statically typed language, while JavaScript is dynamically typed.

• Linux commands are used to interact with the operating system and perform tasks like file management and networking.

• Jquery is a JavaScript library used for DOM manipulation and event handling.

• JS communicates with serverside using AJAX, which stands for Asynchronous JavaScript and XML.

To determine if two line segments with coordinates a1,b1 & a2,b2 intersect, we need to check if the line segments intersect.

• Calculate the slopes of both line segments

• Check if the slopes are equal, if yes, check if the y-intercepts are equal

• If slopes are not equal, calculate the intersection point of the two lines

• Check if the intersection point lies on both line segments

I am excited about technologies that enable seamless integration and automation.

• APIs and microservices

• DevOps tools like Docker and Kubernetes

• Automation tools like Selenium and Jenkins

• Cloud computing platforms like AWS and Azure

• Machine learning and AI technologies

To make an application scalable, consider using cloud services, optimizing database queries, caching frequently accessed data, and using microservices architecture.

• Utilize cloud services like AWS or Azure for scalability on demand

• Optimize database queries to improve performance

• Implement caching mechanisms for frequently accessed data to reduce load on servers

• Use microservices architecture to break down the application into smaller, independent services that can be scaled indi...read more

I am a highly motivated and detail-oriented full stack developer with strong problem-solving skills.

• Pros: Strong problem-solving skills

• Detail-oriented

• Highly motivated

• Experience in full stack development

• Cons: Can be overly meticulous at times

• May need to work on delegating tasks more effectively

Singleton design pattern ensures a class has only one instance and provides a global point of access to it.

• Ensure a private static instance variable in the class.

• Provide a public static method to access the instance, creating it if necessary.

• Use synchronized keyword or double-checked locking to make it thread-safe.

Hooks in React are functions that allow you to use state and other React features in functional components.

• useState - allows functional components to have state

• useEffect - allows side effects in functional components

• useContext - allows functional components to access context

• useReducer - alternative to useState for more complex state logic

• useMemo - memoizes a value to prevent unnecessary re-renders

• useRef - allows functional components to access DOM elements or store mutable va...read more

Optimizing performance of a Nodejs app involves various techniques to improve speed and efficiency.

• Use asynchronous programming to handle multiple requests efficiently

• Implement caching to reduce redundant database queries

• Optimize code by removing unnecessary loops and function calls

• Use a load balancer to distribute traffic evenly across multiple servers

• Monitor and analyze performance using tools like New Relic or Datadog

Exclusive lock is used when a resource is being modified and prevents other processes from accessing it. Shared lock allows multiple processes to read a resource simultaneously.

• Exclusive lock is used for write operations, while shared lock is used for read operations.

• Exclusive lock blocks other processes from acquiring both exclusive and shared locks on the same resource.

• Shared lock allows multiple processes to acquire shared locks on the same resource simultaneously.

• Exclusiv...read more

Linked List is a linear data structure. Stack and Queue are abstract data types.

• Linked List: A collection of nodes where each node points to the next node.

• Stack: A data structure where elements are added and removed from the top only.

• Queue: A data structure where elements are added at the rear and removed from the front only.

• Example: Browser history can be implemented using a Linked List.

• Example: Undo/Redo functionality can be implemented using a Stack.

• Example: Print queue ca...read more

Object oriented model is a programming paradigm that uses objects to represent real-world entities.

• Objects have properties and methods that define their behavior

• Encapsulation, inheritance, and polymorphism are key concepts in OOP

• Examples of OOP languages include Java, C++, and Python

JavaScript has several data types including string, number, boolean, object, function, undefined, and null.

• String: 'hello', '123'

• Number: 123, 3.14

• Boolean: true, false

• Object: { key: 'value' }

• Function: function() { }

• Undefined: undefined

• Null: null

Types of directives in Angular include structural directives, attribute directives, and component directives.

• Structural directives are used to add or remove elements from the DOM based on conditions (e.g. *ngIf, *ngFor)

• Attribute directives are used to change the appearance or behavior of an element (e.g. ngStyle, ngClass)

• Component directives are custom directives that are components themselves (e.g. @Component)

Node.js is a runtime environment that allows JavaScript to be run on the server side.

• Node.js uses an event-driven, non-blocking I/O model which makes it lightweight and efficient.

• It is built on the V8 JavaScript engine from Google Chrome.

• Node.js is commonly used for building scalable network applications.

• It allows developers to use JavaScript for both client-side and server-side development.

• Node.js has a large ecosystem of open source libraries and frameworks available.

Restricting unauthorized access to endpoints can be achieved through authentication mechanisms like JWT, OAuth, API keys, and implementing Multi-Factor Authentication (MFA).

• Implementing JWT (JSON Web Tokens) for authentication and authorization

• Using OAuth for secure authorization between applications

• Utilizing API keys to control access to specific endpoints

• Implementing Multi-Factor Authentication (MFA) for an added layer of security

• Setting up role-based access control (RBAC) ...read more

Keys in React are important for efficient rendering and maintaining component state.

• Keys help React identify which items have changed, are added, or are removed in a list of components.

• Using keys correctly can improve performance by reducing unnecessary re-renders.

• Keys should be unique among siblings but can be reused across different lists.

• Example:

  {items.map(item =>
  • {item.name}
  )}

OSI, TCP & IP are networking protocols used for communication between devices on a network.

• OSI (Open Systems Interconnection) is a conceptual model that defines how data is transmitted over a network.

• TCP (Transmission Control Protocol) is a protocol that ensures reliable transmission of data between devices.

• IP (Internet Protocol) is a protocol that handles the addressing and routing of data packets between devices on a network.

• TCP/IP is a suite of protocols that are commonly ...read more

An operating system is a software that manages computer hardware and software resources.

• It acts as an interface between the user and the computer hardware.

• It provides services to applications and manages system resources.

• Examples include Windows, macOS, Linux, Android, and iOS.

Configure IPsec with NAT-T or use different subnets for the site-to-site connections.

• Use NAT-T (Network Address Translation Traversal) to allow both sites to communicate with the same network.

• Alternatively, use different subnets for the site-to-site connections to avoid conflicts.

• Ensure proper routing and firewall rules are in place to allow traffic between the sites.

• Consider using VPN concentrators or routers that support multiple VPN connections with the same subnet.

• Test th...read more

Python has four parameter passing mechanisms: positional, keyword, default, and variable-length.

• Positional parameters are passed by position.

• Keyword parameters are passed by name.

• Default parameters have a default value if not specified.

• Variable-length parameters can take a variable number of arguments.

Breaking down criteria into stories and assigning points

• Identify user stories based on criteria

• Estimate points for each story based on complexity

• Prioritize stories based on business value

• Create sprint backlog based on prioritized stories

A String is a sequence of characters. String Buffer and String Builder are mutable and faster alternatives to String.

• String is an immutable class in Java.

• String Buffer and String Builder are mutable classes.

• String Buffer is synchronized and thread-safe.

• String Builder is not synchronized and faster than String Buffer.

• Both String Buffer and String Builder have methods to append, insert, delete, and reverse strings.

div is a block-level element while span is an inline element in HTML.

• div is used to group block-level elements and create sections on a webpage.

• span is used to style inline elements or group inline elements together.

• div elements create a line break before and after the element, while span does not.