100+ Full Stack Developer Interview Questions and Answers for Freshers

Determine the minimum number of coins needed to make a given amount using specified denominations, or return -1 if impossible.

• Dynamic Programming Approach: Use an array to store the minimum coins needed for each amount up to the target.

• Initialization: Start with an array filled with a large number (e.g., amount + 1) and set the first element (0) to 0.

• Iterate Through Coins: For each coin, update the array for all amounts that can be formed using that coin.

• Example 1: For coins ...read more

Mutex and Semaphore are synchronization mechanisms used in operating systems to control access to shared resources.

• Mutex is used to provide mutual exclusion, allowing only one thread to access a resource at a time.

• Semaphore is used to control access to a resource by multiple threads, with a specified number of permits available.

• Mutex is binary in nature (locked or unlocked), while Semaphore can have a count greater than 1.

• Example: Mutex can be used to protect critical section...read more

Distributing candies to children based on their ratings while ensuring fairness and minimum total candies required.

• Minimum One Candy: Each child must receive at least one candy, regardless of their rating.

• Higher Rating, More Candies: Children with higher ratings than their neighbors must receive more candies than those neighbors.

• Two-Pass Approach: First, traverse from left to right to ensure the left neighbor condition, then from right to left for the right neighbor condition...read more

Find the minimum number of coins needed to make a given amount using dynamic programming.

• Use dynamic programming to build a solution iteratively.

• Create an array dp where dp[i] represents the fewest coins needed for amount i.

• Initialize dp[0] = 0 (0 coins needed for amount 0) and dp[i] = infinity for all other i.

• For each coin, update the dp array: dp[i] = min(dp[i], dp[i - coin] + 1) if i >= coin.

• Return dp[amount] if it's not infinity; otherwise, return -1.

• Example: coins = [1, ...read more

CPU scheduling is done using algorithms like FCFS, SJF, RR, etc. based on priority and burst time.

• Priorities are assigned to tasks based on their importance and urgency

• FCFS (First Come First Serve) algorithm schedules tasks in the order they arrive

• SJF (Shortest Job First) algorithm schedules tasks with the shortest burst time first

• RR (Round Robin) algorithm schedules tasks in a circular queue with a fixed time slice

• Priority scheduling algorithm schedules tasks based on their ...read more

CPU scheduling algorithms determine the order in which processes are executed by the CPU.

• First Come First Serve (FCFS) - Processes are executed in the order they arrive.

• Shortest Job Next (SJN) - Process with the shortest burst time is executed next.

• Round Robin (RR) - Each process is given a small unit of time to execute in a cyclic manner.

• Priority Scheduling - Processes are executed based on priority levels assigned to them.

• Multi-Level Queue Scheduling - Processes are divided...read more

Abstract class is a class that cannot be instantiated, while an interface is a blueprint of a class with only abstract methods.

• Abstract class cannot be instantiated, but can have both abstract and non-abstract methods.

• Interface can only have abstract methods and cannot have method implementations.

• Method overloading is having multiple methods in the same class with the same name but different parameters.

• Method overriding is implementing a method in a subclass that is already p...read more

Understanding the order of output in JavaScript with setTimeout and console.log is crucial for mastering asynchronous behavior.

• setTimeout is asynchronous and will execute after the specified delay, allowing other code to run first.

• console.log statements execute in the order they are called, regardless of setTimeout.

• Example: console.log('A'); setTimeout(() => console.log('B'), 0); console.log('C'); outputs 'A', 'C', 'B'.

• The event loop handles the execution of code, managing th...read more

Implementing effective strategies enhances customer satisfaction and resolves issues efficiently.

• Active Listening: Engage with customers to understand their concerns fully. For example, paraphrase their issues to confirm understanding.

• Timely Responses: Ensure quick replies to customer inquiries. For instance, aim to respond to emails within 24 hours.

• Personalization: Tailor solutions to individual customer needs. For example, use their name and reference past interactions.

• Foll...read more

Fetching data in a DBMS involves querying the database using structured languages like SQL to retrieve desired information.

• 1. Establish a connection to the database using a driver or library (e.g., JDBC for Java).

• 2. Write a query using SQL (e.g., SELECT * FROM users WHERE age > 30).

• 3. Execute the query through the database connection.

• 4. Retrieve the results, which may be in the form of rows and columns.

• 5. Process the results as needed (e.g., display on a web page or manipulat...read more

Understanding SQL queries is essential for retrieving specific data from tables effectively.

• Use SELECT statement to specify columns: e.g., SELECT name, age FROM users;

• Apply WHERE clause to filter results: e.g., SELECT * FROM orders WHERE status = 'shipped';

• Utilize JOINs to combine data from multiple tables: e.g., SELECT users.name, orders.amount FROM users JOIN orders ON users.id = orders.user_id;

• Aggregate functions like COUNT, SUM, AVG can summarize data: e.g., SELECT COUNT(...read more

Creating a counter app in React involves setting up state, event handlers, and rendering UI components.

• 1. Set up a new React project using Create React App: `npx create-react-app counter-app`.

• 2. Create a functional component, e.g., `Counter`, to manage the counter logic.

• 3. Use the `useState` hook to create a state variable for the counter: `const [count, setCount] = useState(0);`.

• 4. Implement event handlers for increment and decrement functions: `const increment = () => setCo...read more

useEffect manages side effects in components, while Redux centralizes state management across the application.

• useEffect is a React Hook for handling side effects like data fetching or subscriptions within a component.

• Redux is a state management library that provides a global store for managing application state across multiple components.

• useEffect runs after every render or based on dependency changes, while Redux state updates are triggered by dispatched actions.

• Example: use...read more

Generate prime numbers between 10-30 and store in an array

• Iterate through numbers 10 to 30

• Check if each number is prime

• Store prime numbers in an array

React is a JavaScript library for building user interfaces, commonly used for creating interactive web applications.

• React is a front-end library developed by Facebook.

• It allows developers to create reusable UI components.

• React uses a virtual DOM to improve performance by only updating the necessary parts of the actual DOM.

• React can be used with JavaScript to create dynamic and interactive web applications.

• React components are written in JSX, a syntax extension for JavaScript.

A simple React component to implement increment and decrement buttons for a counter.

• Use React's useState hook to manage the counter state.

• Create two buttons: one for incrementing and one for decrementing the counter.

• Handle button clicks with functions that update the state.

• Example: <button onClick={() => setCount(count + 1)}>Increment</button>

• Ensure the counter does not go below zero by adding a condition in the decrement function.

To declare an array in JavaScript, use square brackets and separate elements with commas.

• Declare an array of strings: let myArray = ['apple', 'banana', 'orange'];

• Access elements by index: myArray[0] will return 'apple'.

• Add elements to the array: myArray.push('grape');

• Get the length of the array: myArray.length will return 4.

I expect to grow my skills, contribute to impactful projects, and collaborate with a talented team in this Full Stack Developer role.

• I aim to enhance my technical skills by working on diverse technologies, such as React for front-end and Node.js for back-end development.

• I look forward to taking on leadership responsibilities, mentoring junior developers, and sharing knowledge within the team.

• I hope to contribute to innovative projects that solve real-world problems, like deve...read more

Write a O(N) function to return the second largest number in an array in JavaScript.

• Iterate through the array and keep track of the largest and second largest numbers.

• Handle edge cases like when the array has less than 2 elements.

• Return the second largest number found.

A Full Stack Developer should possess a combination of technical skills, problem-solving abilities, and strong communication skills.

• Proficiency in both front-end and back-end technologies

• Strong understanding of databases and server-side languages

• Ability to work independently and in a team

• Good problem-solving skills and attention to detail

• Effective communication and collaboration with other team members

• Continuous learning and staying updated with new technologies

Schema defines the structure of a database, Indexes improve query performance, Event Loop manages asynchronous operations.

• Schema is a blueprint of a database that defines tables, columns, relationships, etc.

• Indexes are data structures that improve query performance by allowing faster data retrieval.

• Event Loop is a mechanism that manages asynchronous operations in JavaScript.

• Other important concepts for Full Stack Developers include REST APIs, MVC architecture, and version con...read more

Yes, I enjoy working with data structures and algorithms.

• I find data structures and algorithms fascinating and enjoy solving problems using them.

• I have experience implementing various data structures like arrays, linked lists, stacks, queues, trees, and graphs.

• I am familiar with common algorithms such as sorting, searching, and graph traversal algorithms.

• I understand the importance of choosing the right data structure and algorithm for efficient and optimized solutions.

• I have...read more

A round is a circular object or a series of actions that lead back to the starting point.

• A round can refer to a circular object, such as a ball or a wheel.

• In music, a round is a song where different groups start singing the same melody at different times, creating a harmonious effect.

• In sports, a round can refer to a single game or match in a tournament.

• In conversation, a round can refer to each person taking a turn to speak or share their thoughts.

• In programming, rounding is...read more

Write a function to generate binary strings without consecutive 1's.

• Use dynamic programming to keep track of previous two states

• Start with base cases of 0 and 1

• For each new bit, check if adding it would create consecutive 1's

• If not, add it to the string and update the previous two states

• Repeat until desired length is reached

Stateful components store and manage state data, while stateless components do not store state data.

• Stateful components have internal state data that can change over time, while stateless components rely on props passed down from parent components.

• Stateful components are typically class components in React, while stateless components are functional components.

• Examples of stateful components include forms, modals, and sliders, while examples of stateless components include but...read more

Reactjs is preferred nowadays due to its component-based architecture, virtual DOM for efficient updates, and strong community support.

• Component-based architecture allows for reusability and easier maintenance of code.

• Virtual DOM enables efficient updates by only re-rendering components that have changed.

• Strong community support provides a wealth of resources, libraries, and tools for developers.

• React's declarative approach simplifies the process of building complex user inte...read more

Tags and attributes are essential components of HTML for structuring and styling web content.

• Tags are used to define different elements on a webpage, such as headings, paragraphs, images, etc.

• Attributes provide additional information about an element, like specifying its color, size, alignment, etc.

• Example: <h1> is a tag used for defining a top-level heading, and style='color: red;' is an attribute to change its color.