Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Theme : Mini Frontend Projects

Mini Project :

Create a Fully Accessible Dark Mode Toggle + Save Preference in LocalStorage

Requirements :

• Toggle button switches between Light & Dark mode
• Use CSS variables (--bg, --text)
• Use JavaScript to save user preference
• Smooth transition (CSS transition)
• Works even after page refresh

Bonus :

Add a “System Theme” option using prefers-color-scheme.

Small Daily Frontend Challenge

Although weekend focuses on mini-projects, here are micro-challenges too:

Challenge 1 (JS) :

Challenge 2 (CSS Animation) :

Challenge 3 (React):

Challenge 4 (Vue):

Backend Challenge

Focus : Scala, R, Swift, TypeScript

Scala Challenge :

Build a function that computes the moving average of a list using tail recursion.

R Challenge :

Write an R script that:

Swift ( Server-side / Vapor ) :

Create a Vapor route:

GET /users/:id/orders

Returns all orders for a user.

(Design the model + sample JSON response.)

TypeScript ( Node.js + TS ) :

Create a typed Express middleware that validates request headers:

Database Query Challenge

Problems on SQL - HR Database :

1. Write a query to list employees whose salary is above the department average salary.
2. Write a query to find departments where no employees were hired in the last 12 months.

Data Structures & Algorithms Challenge

• Easy:
• Problem : Return the second smallest element in an unsorted array.
• Hint :You don’t need to sort the array. Use two tracking variables.
• Medium :
• Problem : Implement a function to rotate a linked list to the right by k positions.
• Hint :Think of temporarily making the list circular.
• Hard :
• Problem : Given an array, find the maximum sum increasing subsequence.
• Hint : Use DP → dp[i] = arr[i] + best increasing sum ending before i.

Bug of the Day

Focus : Scala, R, Swift, TypeScript

Buggy Code ( Scala ) :

val numbers = List(1, 2, 3)
println(numbers.map(x => x * 2).foreach(println))

Challenge : Find & fix the issue.

Buggy Code ( R ) :

df <- data.frame(a = c(1,2,3), b = c(4,5,6))
print(mean(df))

Challenge : Find & fix the issue.

Buggy Code ( Swift ) :

let name: String? = "John"
print(name.uppercased())

Challenge : Find & fix the issue.

Buggy Code ( TypeScript ) :

function add(a: number, b: number): number {
  return a + b || 0;
}

Challenge : Find & fix the issue.

📋 Daily Micro-Project

Focus : Backend

Task :

Build a Task Manager API with endpoints:

• POST /tasks (create)
• GET /tasks (list)
• PUT /tasks/:id (update)
• DELETE /tasks/:id (remove)

Use any weekend language: Scala, R (Plumber API), Swift (Vapor), TypeScript.

Trivia: 5 Fun Facts

1. The first computer “bug” was an actual moth stuck in a relay (1947).
2. Python was named after “Monty Python,” not the snake.
3. Java was almost named Oak.
4. Linux was originally called Freax by Linus Torvalds.
5. Git was created by Linus Torvalds in just 10 days.

Tool & Resource of the Day

Tool : Postman Mock Server

Great for frontend–backend integration without building actual APIs.

Resource Roundup ( API Testing Special ) :

• MDN Web Docs
• FreeCodeCamp Certifications
• TypeScript Handbook
• Scala Documentation
• Swift.org Tutorials

Interview Question of the Day

Daily Interview Questions

Frontend :
1. What are the pros/cons of using CSS variables?
2. What is the Shadow DOM and why is it useful?
3. How does Vue’s reactivity system track changes?
4. Explain how React batching works.

Backend :
1. Explain the event loop in Node.js.Explain the event loop in Node.js.
2. What is tail recursion in Scala?
3. How does Swift handle memory (ARC)?
4. What is immutability and why is it important?

Database :
1. What is a materialized view?
2. How does partitioning improve performance?
3. What are surrogate keys vs natural keys?

Others :
1. What is a load balancer and why is it used?
2. What is CI/CD?

Daily Quiz Challenge

Frontend CSS ) :

1. Which CSS property controls animation speed?
2. What does ref mean in Vue?
3. What is React’s useMemo used for?

Backend ( Java / Kotlin ) :

1. What is a sealed class in Scala?
2. What is TypeScript’s never type?
3. What is an actor in concurrent systems?

Database :

1. Which SQL clause removes duplicates?

Other :

1. What command lists running processes in Linux?

Mixed Quiz :

1. (Frontend) What does display: contents do?
2. (Backend) What is a deadlock?
3. (Database) What is ACID?

Weekly Cross-Domain Activities ( November 28 to December 04, 2025 )

API of the Day:

Use the Currency Exchange API to convert an amount between currencies.

Linux / DevOps Tip :

Run server health check :

top  
htop  
df -h  
du -sh *  
free -m  
uptime  
journalctl -xe  
systemctl status <service>

Real-World Project of the Week ( November 28 to December 04, 2025 )

Project of the Week:

Build a URL shortener app ( frontend + backend + database ).

Collaborative Project :

Join an open-source project:

“Awesome-DSA-Practice”

(Create algorithms + solutions in multiple languages.)

Case Study :

Analyze how Spotify recommendation engine works.

Users replicate the feature using:

• Cosine similarity
• TF-IDF
• Collaborative filtering