Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Theme : Mini Frontend Projects

Challenge :

Build a Weather Dashboard:

• Use JavaScript + CSS (or Vue/React).
• Fetch data from OpenWeatherMap API.
• Display current temperature, weather condition, and icon.
• Add a toggle for dark/light mode.

Backend Challenge

Focus : Scala, R, Swift, TypeScript

Scala Challenge :

Write a Scala program that:

• Reads a list of integers.
• Groups them into even and odd using partition.
• Prints results.

R Challenge :

Write an R script that:

• Reads a CSV file of employees.
• Calculates average salary by department using aggregate().

Swift Challenge (Vapor) :

Build a simple Vapor API that:

• GET /hello returns "Hello, Swift Backend!".
• POST /echo echoes back the JSON body.

TypeScript (Node.js) Challenge :

Create a TypeScript Express API:

• GET /square/:num returns the square of a number.
• Include request validation (ensure input is a number).

Database Query Challenge

Problems on SQL - HR Database :

1. Write a query to list employees who have never received a promotion.
2. Write a query to find departments where the total salary expense exceeds 1 million.

Data Structures & Algorithms Challenge

• Easy:
• Problem : Check if a string contains a permutation of another string.
• Hint :Sliding Window
• Medium:
• Problem : Find the k most frequent elements in an integer array.
• Hint :Heap / Priority Queue
• Hard:
• Problem : Given a 2D grid of 0 (land) and 1 (water), find the minimum number of days to disconnect the island (convert land to water so island splits).
• Hint :DP + Graphs

Bug of the Day

Focus : Scala, R, Swift, TypeScript

Buggy Code ( TypeScript ) :

function add(a: number, b: number): number {
  return a + b;
}
console.log(add("5", 10));

Challenge : Identify and fix the bug(s).

📋 Daily Micro-Project

Focus : Backend

Task :

Build a JWT-based authentication system (in Swift Vapor / Scala Play / Node.js with TypeScript).

• POST /login issues a JWT token.
• GET /profile requires JWT token to access.

Trivia: 5 Fun Facts

1. R was created in 1993 at the University of Auckland.
2. Scala combines object-oriented and functional programming.
3. Swift was introduced by Apple in 2014 as an alternative to Objective-C.
4. TypeScript was created at Microsoft by Anders Hejlsberg, who also designed C#.
5. PostgreSQL started in 1986 as "POSTGRES."

Tool & Resource of the Day

Tool : Insomnia (API client like Postman)

• Great for testing REST and GraphQL APIs.
• Simple and lightweight.

Resource Roundup :

• Insomnia Docs
• Free TypeScript course: TypeScript Handbook
• Swift Vapor guide: Vapor Docs

Interview Question of the Day

Daily Interview Questions

Frontend :
1. What is the difference between inline, inline-block, and block in CSS?
2. Explain the difference between controlled and uncontrolled inputs in React.
3. How does Vue.js handle two-way binding internally?
4. What are CSS variables, and why are they useful?

Backend :
1. Explain immutability in Scala and why it’s useful.
2. How does R handle vectorized operations?
3. Explain the difference between synchronous and asynchronous APIs in Swift Vapor.
4. What are the advantages of using TypeScript over JavaScript for backend development?

Database :
1. What is a materialized view in SQL?
2. Explain database sharding and when it’s useful.
3. What is the difference between OLAP and OLTP databases?

Others :
1. What are containers vs. virtual machines?
2. What is continuous monitoring in DevOps?

Daily Quiz Challenge

Frontend :

1. Which CSS property is used for custom properties (variables)?
• --var
• $var
• --custom
• var()
2. In React, which hook replaces lifecycle methods like componentDidMount?
• useReducer
• useEffect
• useMemo
• useCallback
3. In Vue.js, which directive repeats elements?
• v-show
• v-bind
• v-for
• v-model

Backend :

1. Which keyword in Scala is used to define an immutable value?
• let
• const
• val
• var
2. In R, which function reads a CSV file?
• read.csv()
• csv.read()
• import.csv()
• load.csv()
3. Which keyword is used to declare a constant in TypeScript?
• const
• let
• var
• final

Database :

1. Which SQL function returns the number of rows?
• SUM()
• COUNT()
• ROWS()
• TOTAL()

Other :

2. Who designed the TypeScript language?
• Brendan Eich
• Anders Hejlsberg
• James Gosling
• Guido van Rossum

Mixed Quiz :

3. Which of the following is true?
• Swift is not open-source.
• TypeScript is a superset of JavaScript.
• R cannot handle statistical operations.
• Scala doesn’t support functional programming.

Weekly Cross-Domain Activities ( September 19 to September 25, 2025 )

API of the Day:

Use the NewsAPI to build a “Top Headlines Dashboard” with filtering by country and category.

Linux / DevOps Tip :

Run htop in Linux to monitor CPU, memory, and processes in real time.

Real-World Project of the Week ( September 19 to September 25, 2025 )

Project of the Week:

Build a Task Manager Web App (Frontend: React/Vue, Backend: Node.js/Scala, Database: PostgreSQL).

Collaborative Project :

Contribute to freeCodeCamp’s Open Source Projects on GitHub.

Case Study :

Analyze Slack’s architecture – how it handles real-time messaging and scaling – and try to replicate a mini chat app.