Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Theme : Mini Frontend Projects

Challenge :

Build a “Theme Switcher Dashboard” (Dark/Light Mode + Accent Color Picker)

Requirements :

• Include toggle buttons for Dark Mode and Light Mode.
• Add color swatches to change accent color (e.g., blue, green, purple).
• Use CSS variables for color themes.
• Implement logic in JavaScript, React, or Vue.js.

Bonus Challenges (optional) :

• Smooth transition animation when switching themes.
• Save theme preference using localStorage.

Hint : Use CSS :root with --variable for themes and toggle them dynamically using JS or component state.

Backend Challenge

Focus : Scala, R, Swift, TypeScript

Scala Challenge :

Create a REST API in Scala using Akka HTTP to fetch and filter employee data by department and salary range.

R Challenge :

Write an R script to import a large CSV of employee data, group by department, and calculate average salary — without loading entire dataset into memory.

Swift Challenge (Vapor) :

Build a simple endpoint /employees/:id that returns JSON data for a single employee.

TypeScript (Node.js) Challenge :

Using Express + TypeScript, create a middleware that logs every request’s method, URL, and timestamp.

Hint : Focus on type safety, async handling, and clean module organization.

Database Query Challenge

Problems on SQL - HR Database :

1. Write a SQL query to find employees who earn above the average salary of their department.
2. Write a SQL query to list departments where no employee has joined in the last 6 months.

Hint : Use AVG(), GROUP BY, and NOT EXISTS subqueries strategically.

Data Structures & Algorithms Challenge

• Easy:
• Problem : Implement a function to check whether a string is a palindrome using a stack.
• Hint :Use push() and pop() operations effectively.
• Medium:
• Problem : Given an array of integers, find the length of the longest consecutive sequence.
• Hint :Use a HashSet to store elements and track sequences efficiently.
• Hard:
• Problem : Implement an LRU (Least Recently Used) Cache using a Doubly Linked List + HashMap.
• Hint :Optimize for O(1) get() and put() operations

Bug of the Day

Focus : Scala, R, Swift, TypeScript

Buggy Code ( Scala ) :

val nums = List(1, 2, 3)
println(nums.map(x => x * x))
println(nums.reduce((a, b) => a + b))
println(nums.map(x => x + 1))

Find the logic bug - the output is not as expected after using map.

Buggy Code ( R ) :

df <- data.frame(a=c(1,2,3), b=c(4,5,6))
df$c = df$a + df$b
print(df["c"])

Why is column c showing NULL?

Buggy Code ( Swift ) :

var list = [1, 2, 3]
for i in list {
    list.append(i * 2)
}
print(list)

What goes wrong? Fix the logic.

Buggy Code ( TypeScript ) :

let user = { name: "Alex", age: 25 };
console.log(user?.address.city);

What’s the issue here? Fix it to safely access nested properties.

📋 Daily Micro-Project

Focus : Backend

Task :

Build a RESTful Book Inventory API (choose any weekend language).

Features :

• Add a new book (title, author, price).
• Update a book’s price.
• Retrieve all books.
• Delete a book by ID.

Bonus : Integrate with a local SQLite or MongoDB instance.

Trivia: 5 Fun Facts

1. The first computer bug was an actual moth trapped in a Harvard Mark II relay.
2. The word "Python" comes from Monty Python, not the snake.
3. CSS Grid was officially added to browsers only in 2017.
4. The original Java name was Oak, inspired by a tree outside James Gosling’s office.
5. GitHub’s mascot “Octocat” was drawn by an illustrator for fun, not for GitHub itself.

Tool & Resource of the Day

Tool : Postman

• Perfect for testing APIs quickly.
• Supports environment variables, test scripts, and CI integration.

Resource Roundup :

• Insomnia Docs
• MDN Web Docs
• Eloquent JavaScript (free eBook)
• Frontend Mentor
• JSONPlaceholder — mock API for testing

Interview Question of the Day

Daily Interview Questions

Frontend :
1. What is event bubbling and how can it be stopped?
2. Explain how React’s useEffect dependency array works.
3. How do Vue.js computed properties differ from methods?
4. What is the purpose of the key attribute in React lists?

Backend :
1. Explain the difference between blocking and non-blocking I/O.
2. What are closures in JavaScript, and how are they used in Node.js?
3. Describe how dependency injection works in backend frameworks.
4. How do you manage environment variables securely in a backend system?

Database :
1. What is a correlated subquery?
2. Explain the difference between DELETE, TRUNCATE, and DROP.
3. What is database normalization, and why is it important?

Others :
1. What is continuous integration (CI)?
2. Explain what a container image is and how it differs from a virtual machine.

Daily Quiz Challenge

Frontend :

1. What does position: sticky; do in CSS?
2. What will typeof null return in JavaScript?
3. In React, what happens if you call setState() inside render()?

Backend :

1. In Node.js, what is the purpose of the cluster module?
2. What’s the output of Python’s bool([])?
3. In Rust, what does the ? operator do?

Database :

1. What is the difference between HAVING and WHERE clauses?

Other :

2. Which Linux command is used to check running processes?

Mixed Quiz :

3. Combine React + SQL + Python: "If a REST API in Python fetches SQL data for a React frontend, what HTTP method should be used for data retrieval?"

Weekly Cross-Domain Activities ( October 11 to October 17, 2025 )

API of the Day:

Integrate the OpenWeatherMap API and build a small weather widget showing temperature, city, and weather icon.

Linux / DevOps Tip :

Use top, htop, and vmstat to monitor CPU, memory, and process usage live on Linux servers.

Real-World Project of the Week ( October 11 to October 17, 2025 )

Project of the Week:

Build a “Personal Finance Tracker” — Track expenses, visualize data with charts, and store in a backend DB.

Collaborative Project :

Contribute to an open-source Habit Tracker App on GitHub (Frontend: React, Backend: Node.js).

Case Study :

Study how Spotify’s recommendation system works — replicate a mini version using a dataset and cosine similarity.