DEV Community: Karthick (k)

JavaScript Callbacks

Karthick (k) — Wed, 02 Sep 2026 03:24:30 +0000

A callback function is a function that is passed as an argument to another function and executed later.

A function can accept another function as a parameter.
Callbacks allow one function to call another at a later time.
A callback function can execute after another function has finished.

function greet(name, callback) {
    console.log("Hello, " + name);
    callback();
}

function sayBye() {
    console.log("Goodbye!");
}

greet("Ajay", sayBye);

Working of Callbacks in JavaScript

JavaScript executes code line by line (synchronously), but sometimes we need to delay execution or wait for a task to complete before running the next function. Callbacks help achieve this by passing a function that is executed later.

Callbacks for Asynchronous Execution

console.log("Start");

setTimeout(function () {
    console.log("Inside setTimeout");
}, 2000);

console.log("End");

When to Use and Avoid Callbacks
Use callbacks when

Handling asynchronous tasks (API calls, file reading).
Implementing event-driven programming.
Creating higher-order functions.

Avoid callbacks when:

Code becomes nested and unreadable (use Promises or async/await).
You need error handling in asynchronous operations (Promises are better).

How Python Can Help You Develop a Healthier Mindset Through Mindful Programming

Karthick (k) — Tue, 01 Sep 2026 13:46:55 +0000

Title: Solving Common Python Problems: A Practical Approach

Summarise what you learned from solving each problem. This helps readers understand the importance of the problems and encourages them to explore similar challenges.

#1) Count of Digits

given_number=1234;
count=0

while given_number>0:
    digit=given_number%10;
    count+=1;

    given_number=given_number//10;

print(count)

#2) Sum of Digits

given_answe=274;
count=0;
sum=0;

while given_answe>0:
    digits=given_answe%10;
    count+=1
    sum=sum+digits;

    given_answe=given_answe//10;

print(count);
print(sum)

#3) Reverse the number


Given_number_ans=12345;

reversed_num=0;
while Given_number_ans>0:
    digits=Given_number_ans%10;

    reversed_num=(reversed_num*10)+digits


    Given_number_ans=Given_number_ans//10;

print(reversed_num)

#4) Factorial

#n!=n*(n-1)*(n-2)...


N=5;
i=1;
total=1;

while(i<=N):
    total=total*i;
    i+=1;

print(f'sum of Factorial is {N} is {total}')

#5) Greatest Common Divisor


Number1=36;
Number2=94;

Gcd=0;

smallest=min(Number1,Number2);

for i in range(1,smallest+1):
    if Number1%i==0 and Number2%i==0:
        Gcd=i;


print(f"The GCD of {Number1} and {Number2} is {Gcd}")

Practice Problems

Karthick (k) — Tue, 01 Sep 2026 13:25:52 +0000

In this blog, I have done basic conditional statement questions and answer I have practised some important Python number-based programs. These programs helped me understand while loops, functions, conditional statements, digit extraction, mathematical operations, and problem-solving logic.

#1) Palindrome

class Solution:
    def isPalindrome(self, n):
        if n < 0:
            return False

        original = n
        reverse = 0

        while n > 0:
            digit = n % 10
            reverse = (reverse * 10) + digit
            n //= 10

        return original == reverse


print(Solution().isPalindrome(121))
print(Solution().isPalindrome(-121))
print(Solution().isPalindrome(10))

#2) Armstrong Number
import math

Is_Armstong = 370
count = 0
sum = 0
orginal_number = Is_Armstong
temp = Is_Armstong

while temp > 0:
    count += 1
    # Bug 1 fixed: Use / inside math.floor, OR just use // 
    temp = mathfloor(temp / 10)  

while Is_Armstong > 0:
    the_digits = Is_Armstong % 10

    # Bug 2 fixed: Use math.pow() to calculate powers!
    # math.pow returns a decimal (like 27.0), so we wrap it in math. floor to make it a whole number
    . sum = sum + math. floor(math.pow(the_digits, count))  

    Is_Armstong = math.floor(Is_Armstong / 10)

if sum == orginal_number:
    print('It is Armstrong number')
else:
    print('It is not Armstrong number')

#3) Neon Number
import math

Neon_number=9;
sum=0;
temp=Neon_number*Neon_number;
print(temp);

orginal_number=Neon_number;


while temp>0:
    the_digits=temp%10;

    sum=sum+the_digits;

    temp=math.floor(temp//10);

if orginal_number==sum:
    print('It is Neon number');
else:
    print('It is not Neon Number')

#4) Strong Number
import math

Strong_number=145;
orginal_strong=Strong_number;

sum=0;

while Strong_number>0:

    the_digits=Strong_number%10;

    i=1;
    stong_values=1;

    while(i<=the_digits):
        stong_values=stong_values*i;
        i+=1

    sum=sum+stong_values;

    Strong_number=math.floor(Strong_number//10);


if sum==orginal_strong:
    print("It is Strong number");
else:
    print("It is not Strong number");

#5) Addition of first n numbers

numbers=15;
i=0;
fact=0;

while i<=numbers:
    fact=fact+i;
    i+=1;

print(f'sum of frist {numbers} is {fact}')

    #  n * (n + 1) / 2 --- important formula of the frist n sum of numbers.

The Journey of Creating a Custom Hook that Improves User Experience

Karthick (k) — Mon, 31 Aug 2026 07:04:07 +0000

Write a blog about creating a new project for a custom hook that improves user experience.

What you should learn from this project
This project teaches a very important React idea: how to copy text to the clipboard with one click.

1) Learn the main goal
The app is about improving user experience.

Instead of asking users to:

select text
press Ctrl + C
then paste it somewhere else
you give them a button that does it automatically.

import { useState } from 'react ';

export function useCopyToClipboard() {
  const [copiedText, setCopiedText] = useState('')

  const copyToClipboard = async (text) => {
    if (!text) {
      setCopiedText('')
      return false
    }

    try {
      if (navigator?.clipboard?.writeText) {
        await navigator.clipboard.writeText(text)
      } else {
        const textarea = document.createElement('textarea')
        textarea.value = text
        textarea.setAttribute('readonly', '')
        textarea. style.position = 'fixed'
        textarea. style.top = '-9999px'
        textarea. style.left = '-9999px'

        document.body.appendChild(textarea)
        textarea.select()
        document.execCommand('copy')
        document.body.removeChild(textarea)
      }

      setCopiedText(text)
      return true
    } catch (error) {
      console.error('Copy failed:', error)
      setCopiedText('')
      return false
    }
  }

  return [copiedText, copyToClipboard]
}

## Project idea

When users need to copy a value like an API key, token, link, or code, it is better to make the action easy with one click instead of forcing them to type Ctrl + C manually.

This app demonstrates that idea with a fake API key and a Copy button.

What Is the Zoom Developer Platform? A Guide for Builders

Karthick (k) — Sat, 29 Aug 2026 15:00:41 +0000

Introduction: The Hook:

Zoom is no longer just a meeting app; it is a full collaboration ecosystem. The Core Definition: Explain that the Zoom Developer Platform gives programmers access to the same video, audio, and AI infrastructure that powers Zoom.The Goal: Help developers turn standalone tools into connected, in-meeting experiences.

*Core Pillars of the Platform: *

REST APIs: Use endpoints to manage users, configure settings, pull meeting reports, and automate workflows.
Webhooks & Event Subscriptions: Listen for real-time triggers like meeting start/end, participant joins, or chat alerts.
Meeting & Video SDKs: Embed HD video/audio directly into your own web, mobile, or desktop apps with custom user interfaces.
Zoom Apps: Build web apps that run inside the active Zoom client toolbar for live collaboration.

AI & Advanced Tools: Leverage AI services and modern additions like Model Context Protocol (MCP) servers to extract transcripts and summaries.

Python Practice Problems

Karthick (k) — Fri, 28 Aug 2026 11:29:53 +0000

# 1. 1   1   1   1   1

for i in range(5):
    print(1);

# 1 2 3 4 5 


number=1;

while number<=5:
    print(number,end=" ")
    number+=1

#3) 1   3   5   7   9

Number=1

while Number<=9:
    print(Number,end=" ");
    Number+=2

#4) 3   6   9   12  15

Number=3

while Number<=15:
    print(Number,end=" ");
    Number+=3;

#5) Multiples of 3 and 5 


for number in range(1,101):
    if number%3==0 and number%5==0:
        print(number)

#6) Multiples of 3 or 5 

for i in range(1,20):
    if i%3==0 or i%5==0:
        print(i)

#7) Divisors of a given number


Given_values=12;

i=1;
while i<=Given_values:
    if Given_values%i==0:
        print(i);
    i+=1

#8) Count of Divisors of given number


Given_values=36;
count=0

i=1;
while i<=Given_values:
    if Given_values%i==0:
        print(i,end=" ");
        count+=1
    i+=1
print()
print(count)

#9) Prime Number

Given_prime_number=19;
i=2
is_prime=True;

while i<Given_prime_number:
    if Given_prime_number%i==0:
        is_prime=False
        break;
    i+=1;

if is_prime==True:
    print("It is a prime number");
else:
    print("Not a prime number")

#10) Reverse printing a number

Given_number=122;

while Given_number>0:
    digit=Given_number%10;

    Given_number=Given_number//10;

    print(digit,end='')

This is the collection of problems I have completed. I didn't share any outputs; instead, please try to determine the outputs yourself, and feel free to provide feedback in the comments.

Java Methods

Karthick (k) — Thu, 27 Aug 2026 07:13:46 +0000

Java Methods are blocks of code that perform a specific task. A method allows us to reuse code, improving both efficiency and organisation. All methods in Java must belong to a class. Methods are similar to functions and expose the behaviour of objects.

A method allows us to write a piece of logic once and reuse it wherever needed in the program.
This helps keep your code clean, organised, easier to understand and manage.

Passing Parameters:
Parameters are nothing but the variables that are passed inside the parentheses of a method. We can pass a single or more parameters of different data types inside our method.

Example 1: Passing a single parameter

public class MethodExample {

    static void Details(String name) {
        System.out.println("Welcome " + name);
    }

    public static void main(String[] args) {
        Details("Mitali");
    }
}

Output:

Welcome Mitali

Method Overloading

Method Overloading is when we create multiple methods with the same name but pass different types of parameters inside it. This allows us to overload the same method many times. We only need to pass a different type or a different number of parameters inside it.

Example:

public class MethodOverloadEx {
    static void Details(String name, int marks) {
        System. out.println("Welcome " + name);
        System. out.println("Your got "+ marks + " marks in exam.");
    }

    static void Details(String name, double marks) {
        System.out.println("Welcome " + name);
        System.out.println("Your got "+ marks + " marks in exam.");
    }

    public static void main(String[] args) {
        Details("Ridhi", 89);
        Details("Ritesh", 93.5);
    }
}

Output:

Welcome, Ridhi
You scored 89 marks in the exam.
Welcome, Ritesh
You scored 93.5 marks in the exam.

Classes and Objects in Java

Karthick (k) — Wed, 26 Aug 2026 06:26:16 +0000

In Java, classes and objects form the foundation of Object-Oriented Programming (OOP). They help model real-world entities and organise code in a structured way.

A class is a blueprint used to create objects that share common properties and behaviour.
An object is an instance of a class. It represents a specific entity created from the class template.

Classes

A class in Java defines a new data type that can include fields (variables) and methods to define the behaviour of the objects created from the class.

class ClassName {
    // Fields
    dataType fieldName;

    // Constructor
    ClassName(parameters) {
        //Initialise fields
    }

    // Methods
    returnType methodName(parameters) {
        // Method body
    }
}

ClassName: The name of the class.
fieldName: Variables that hold the state of the class.
Constructor: A special method used to initialise objects.
methodName: Functions defined within the class to perform actions.

Objects

An object is an instance of a class. It is created using the new keyword followed by the class constructor.

Syntax

ClassName objectName = new ClassName(arguments);

Difference between Local Variable and Global variables:

*Quick Comparison Table: What is static and non-static in Java *

Java Basics

Karthick (k) — Tue, 25 Aug 2026 06:01:29 +0000

Introduction to Programming Paradigms

1. Imperative Programming Paradigm

Imperative programming is one of the oldest programming paradigms and is closely related to machine architecture and Von Neumann architecture. It works by changing the program state through assignment statements and executes tasks step-by-step to achieve the desired result.

Examples of Imperative programming paradigms:

C: developed by Dennis Ritchie and Ken Thompson
Fortran: developed by John Backus for IBM
BASIC: developed by John G Kemeny and Thomas E Kurtz

2. Procedural programming paradigm:

This paradigm emphasizes on procedure in terms of under lying machine model. There is no difference in between procedural and imperative approach. It has the ability to reuse the code and it was a boon at that time when it was in use because of its reusability.

Examples of Procedural programming paradigm:

C: developed by Dennis Ritchie and Ken Thompson
C++: developed by Bjarne Stroustrup
Java: developed by James Gosling at Sun Microsystems
ColdFusion: developed by J J Allaire
Pascal: developed by Niklaus Wirth

2. Object-oriented programming: The program is written as a collection of classes and objects which are meant for communication. The smallest and basic entity is an object, and all kind of computation is performed on the objects only. More emphasis is on data rather than procedures. It can handle almost all kind of real-life problems which are today in scenario.

Examples of Object-Oriented programming paradigm:

Simula: first OOP language
Java: developed by James Gosling at Sun Microsystems
C++: developed by Bjarne Stroustrup
Objective-C: designed by Brad Cox
Visual Basic .NET: developed by Microsoft
Python: developed by Guido van Rossum
Ruby: developed by Yukihiro Matsumoto
Smalltalk: developed by Alan Kay, Dan Ingalls, and Adele Goldberg

2. Functional programming paradigms:

Functional programming is a paradigm based on mathematical functions where computation is performed through the execution of functions. It focuses on using functions for specific tasks while keeping data loosely coupled and minimising changes in program state. Some of the languages, like Perl and JavaScript, mostly use this paradigm.

Examples of Functional programming paradigm:

JavaScript: developed by Brendan Eich
Haskell: developed by Lennart Augustsson, Dave Barton
Scala: developed by Martin Odersky
Erlang: developed by Joe Armstrong, Robert Virding
Lisp: developed by John McCarthy
ML: developed by Robin Milner
Clojure: developed by Rich Hickey

Data Types

Java has 8 primitive data types to store different values.

byte: 1 byte, small integers (-128 to 127)
short: 2 bytes, integers
int: 4 bytes, integers (Most common)
long: 8 bytes, large integers
float: 4 bytes, decimals (needs 'f' suffix, e.g., 3.14f)
double: 8 bytes, decimals (Most common for fractions)
char: 2 bytes, single character (e.g., 'A')
boolean: 1 bit, true or false

Summary
We covered the fundamental building blocks of Java Data Types, Introduction to Programming Paradigms.

Java Tutorial

Karthick (k) — Mon, 24 Aug 2026 09:07:11 +0000

Java is a high-level, object-oriented programming language used to build web apps, mobile applications, and enterprise software systems.

Java is a platform-independent language, which means code written in Java can run on any device that supports the Java Virtual Machine (JVM).
Syntax and structure are similar to C-based languages like C++ and C#.

Hello World Program

The following is a simple program that displays the message “Hello, World!” on the screen.

public class Geeks{
    public static void main(String[] args) {
        System. out.println("Hello World!");
    }
}

Output

Hello World!

Basics

Understand core Java concepts such as syntax, variables, data types, loops, and decision-making to start your programming journey.

**JDK (Java Development Kit) **provides tools and libraries to develop Java applications, working with JRE and JVM.

JRE (Java Runtime Environment) offers the libraries and JVM needed to run Java programs.

JVM (Java Virtual Machine) executes the compiled Java bytecode on the system.

My useReducer Learning Journey: From 'What is this?' to Building Real Projects

Karthick (k) — Sun, 23 Aug 2026 06:45:09 +0000

My useReducer Learning Journey: From "What is this? ' to Building Real Projects.

A few days ago, I couldn't tell you what UseReducer was. Today I have built a TODO list and a Quiz app with it. I want to share exactly how that happened- confusion and all -- because I think a lot of beginners hit the same wall I did.

const [state, dispatch] = useReducer(reducerFunction, initialState);

Project 1: Quiz App

import { useReducer, useState } from 'react'
import reactLogo from './assets/react.svg'
import viteLogo from './assets/vite.svg'
import heroImg from './assets/hero.png'
import './App.css'


const Question = [
  {
    Question: "What is the capital of India?",
    Options: ["Mumbai", "Delhi", "Chennai", "Kolkata"],
    answer: "Delhi"
  },
  {
    Question: "Which hook is used for complex state?",
    Options: ["useState", "useReducer", "useEffect", "useRef"],
    answer: "useReducer"
  },
  {
    Question: "React is a",
    Options: ["Library", "Language", "Database", "Frameworks"],
    answer: "Library"
  },
  {
    Question: "What is the longest river in the world?",
    Options: ["Amazon River", "The Nile River", "The Yangtze River", "The Mississippi River"],
    answer: "The Nile River"
  },
    {
    Question: "Which country is home to the most natural lakes in the world?",
    Options: ["Canada", "United States", "Russia", "Australia"],
    answer: "Canada"
  },



];

const initialState = {
  currentQuestion: 0,
  score: 0,
  showResults: false
};



function QuizReducer(state, action) {
  switch (action.type) {
    case "Answer":
      const isCorrect = action.payload === Question[state.currentQuestion].answer;

      return {
        ...state,
        score: isCorrect ? state.score + 1 : state.score,
        currentQuestion: state.currentQuestion + 1

      }



    default:
      return state;

  };
}



function App() {
  const [state, dispatch] = useReducer(QuizReducer, initialState);

  if (state.currentQuestion >= Question.length) {
    return (
      <div>
        <h2>Quiz App</h2>
        <p> Your Score : {state.score} /{Question.length}</p>
      </div>
    );
  }
  const current = Question[state.currentQuestion];

  return (
    <div>
      <h2>Quiz App</h2>
      <h3>{current.Question}</h3>
      {current.Options.map((option) => (
        <button
          key={option}
          onClick={() => dispatch({ type: "Answer", payload: option })}
        >
          {option}
        </button>
      ))}
    </div>
  );

}

export default App

This is the expected output:

React Hooks Types: A Simple Guide For Better Components

Karthick (k) — Fri, 21 Aug 2026 09:15:23 +0000

What are React Hooks?

React Hooks allow developers to manage state and lifecycle methods within functional components. Before hooks, stateful logic was only possible using class components. Now, hooks make it easier to manage local state, fetch data, and encapsulate reusable logic in a structured manner.

Types of React Hooks in Functional Components

React Hooks can be divided into two categories: built-in hooks and custom hooks. Built-in hooks provide direct functionality, while custom hooks encapsulate reusable logic for better code modularity.

Built-in React Hooks Built-in hooks provide fundamental functionalities for managing state, side effects, and context.

*1 useState *– Managing Local State
Within functional components, the useState hook aids in local state management. The state variable and an update function are included in the array that is returned.

2 useEffect – Handling Side Effects
The useEffect hook is used for executing side effects, such as fetching data, subscriptions, and manually manipulating the DOM.

3 useContext – Managing Global State with React Context
The useContext hook simplifies global state management within a component tree.

4 useReducer – Managing Complex State Logic
When state logic becomes complex, useReducer is a better choice than useState. It uses a reducer function to determine state transitions.

2. Custom Hooks in React

Custom hooks help encapsulate reusable logic while keeping functional components clean.

Creating a Custom Hook for Data Fetching
A custom hook can be used to handle repetitive logic such as fetching data.
Using the useFetch Hook

3. Optimising Performance with React Hooks

React provides hooks like useCallback and useMemo to enhance performance by reducing re-render cycles.

1. useCallback – Preventing Unnecessary Function Re-Creation
A callback function inside a component is recreated on each render. useCallback ensures that the function reference remains the same unless dependencies change.

2 useMemo – Memoising Expensive Computations
useMemo optimises performance by caching computed values.

Managing Lifecycle with useEffect React Hooks replace traditional lifecycle methods such as componentDidMount. The useEffect hook runs logic when a component mounts.