Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Theme : React Hooks & State Management

Challenge :

Build a React Counter App with the following features:

• + and – buttons to increment/decrement the counter.
• A Reset button.
• Use useState hook.

Bonus : Persist count in localStorage using useEffect.

Backend Challenge

Focus : Node.js & Go

Node.js Challenge :

Create an Express.js API with two endpoints:

• GET /users → Returns a list of users from a mock JSON file.
• POST /users → Accepts a new user and adds it to the JSON file.

Go Challenge :

Write a Go program to implement a concurrent worker pool:

• Accepts a list of jobs.
• Uses goroutines to process them.
• Prints results as they complete.

Database Query Challenge

Problems on SQL - HR Database :

1. Write a query to find employees who joined in the last 6 months
2. Write a query to list employees earning the highest salary in each department.

Data Structures & Algorithms Challenge

• Easy:
• Problem : Check if two strings are anagrams of each other.
• Hint :Hashing
• Medium:
• Problem : Find the lowest common ancestor of two nodes in a BST.
• Hint :Binary Search Tree
• Hard:
• Problem : Given a grid with obstacles, find the shortest path from top-left to bottom-right using BFS.
• Hint :Graph + BFS/DFS

Bug of the Day

Focus : Node.js, Go

Buggy Code ( Node.js ) :

const fs = require('fs');
fs.readFile('data.json', (data, err) => {
  if(err) {
    console.log("Error:", err);
  }
  console.log("File Data:", data.toString());
});

Challenge: : Find and fix the bug(s).

📋 Daily Micro-Project

Focus : Frontend

Task :

Build a React search filter component:

• Input box filters a list of names in real time.
• Use useState and filter().

Trivia: 5 Fun Facts

1. React was developed by Facebook in 2013.
2. Node.js is built on Google’s V8 engine.
3. Go (Golang) was developed at Google in 2009.
4. SQL’s NULL is not equal to anything, not even itself.
5. The first Go mascot is the gopher, designed by Renee French.

Tool & Resource of the Day

Tool : VS Code Extensions

• ESLint (JavaScript/Node.js linting).
• Prettier (code formatting).
• Go Extension (Go development support).

Resource Roundup :

• React Docs
• Go by Example
• Node.js Docs

Interview Question of the Day

Daily Interview Questions

Frontend :
1. Explain the difference between useState and useReducer in React.
2. What is the purpose of useEffect?
3. What is the difference between controlled and uncontrolled components in React?
4. How does React’s reconciliation algorithm work?

Backend :
1. What is event-driven architecture in Node.js?
2. Explain concurrency in Go.
3. How does Go manage garbage collection?
4. What are middleware functions in Express.js?

Database :
1. What is a composite key in SQL?
2. Explain the difference between clustered and non-clustered indexes.
3. How do foreign key constraints maintain referential integrity?

Others :
1. What is the CAP theorem in distributed systems?
2. Explain the concept of API rate limiting.

Daily Quiz Challenge

Frontend :

1. In React, which hook is used to manage local state?
• useContext
• useState
• useReducer
• useRef
2. What is JSX in React?
• A templating engine
• A syntax extension for JavaScript
• A CSS preprocessor
• A database query language
3. Which attribute in React replaces class in JSX?
• css
• style
• className
• classList

Backend :

1. In Node.js, which module is used to create a web server?
• http
• fs
• net
• express
2. Which Go keyword is used to start a goroutine?
• thread
• routine
• go
• run
3. Which method in Express.js is used to define a middleware?
• app.route()
• app.middleware()
• app.use()
• app.set()

Database :

1. Which SQL clause is used to group rows that have the same values?
• GROUP BY
• HAVING
• ORDER BY
• DISTINCT

Other :

2. Who created the Go programming language?
• Guido van Rossum
• Robert Griesemer, Rob Pike, and Ken Thompson
• Brendan Eich
• James Gosling

Mixed Quiz :

3. Which of the following is true?
• React doesn’t support hooks.
• Node.js is single-threaded.
• Go doesn’t support concurrency.
• SQL always requires indexes.

Weekly Cross-Domain Activities ( September 12 to September 18, 2025 )

API of the Day:

Integrate the NASA Astronomy Picture of the Day API and display today’s image.

Linux / DevOps Tip : Use df -h to check disk usage and du -sh for folder sizes.

Real-World Project of the Week ( September 12 to September 18, 2025 )

Project of the Week:

Build a habit tracker app ( Frontend: React/Vue + Backend: Node.js/Scala + DB: PostgreSQL).

Collaborative Project :

Join the open-source project FreeCodeCamp

Case Study :

Study how Netflix handles recommendations using collaborative filtering.