Swap Case

Transform text by swapping the case of each character (uppercase becomes lowercase and vice versa).

🚀 Features

• Lightweight - Only ~200B minified + gzipped
• Type-safe - Full TypeScript support with comprehensive type definitions
• Zero dependencies - No external dependencies
• Tree-shakeable - ES modules support
• Universal - Works in browsers, Node.js, and serverless environments
• Well-tested - Comprehensive test suite with edge cases

📦 Installation

# npm
npm install text-swap-case

# yarn
yarn add text-swap-case

# pnpm
pnpm add text-swap-case

# bun
bun add text-swap-case

🎯 Quick Start

import { swapCase } from "text-swap-case";

console.log(swapCase("Hello World")); // "hELLO wORLD"
console.log(swapCase("JavaScript")); // "jAVAsCRIPT"
console.log(swapCase("CamelCase")); // "cAMELcASE"

📖 Usage

ES Modules (Recommended)

import { swapCase } from "text-swap-case";

console.log(swapCase("Hello")); // "hELLO"

CommonJS

const { swapCase } = require("text-swap-case");

console.log(swapCase("Hello")); // "hELLO"

TypeScript

import { swapCase } from "text-swap-case";

const result: string = swapCase("Hello World");
console.log(result); // "hELLO wORLD"

🔄 Transformation Examples

Basic Transformations

import { swapCase } from "text-swap-case";

// Simple cases
swapCase("Hello"); // "hELLO"
swapCase("HELLO"); // "hello"
swapCase("hello"); // "HELLO"

// Mixed cases
swapCase("Hello World"); // "hELLO wORLD"
swapCase("CamelCase"); // "cAMELcASE"
swapCase("PascalCase"); // "pASCALcASE"
swapCase("snake_case"); // "SNAKE_CASE"
swapCase("kebab-case"); // "KEBAB-CASE"

// Complex examples
swapCase("JavaScript"); // "jAVAsCRIPT"
swapCase("XMLHttpRequest"); // "xmlhTTPrEQUEST"
swapCase("iPhone"); // "IpHONE"
swapCase("macOS"); // "MACos"

Edge Cases

import { swapCase } from "text-swap-case";

// Numbers and symbols (unchanged)
swapCase("Hello123"); // "hELLO123"
swapCase("[email protected]"); // "[email protected]"
swapCase("User_123"); // "uSER_123"

// Empty and whitespace
swapCase(""); // ""
swapCase("   "); // "   "
swapCase("\n\t"); // "\n\t"

// Unicode characters
swapCase("Café"); // "cAFÉ"
swapCase("Naïve"); // "nAÏVE"
swapCase("Résumé"); // "rÉSUMÉ"

🌍 Real-World Examples

Text Obfuscation

import { swapCase } from "text-swap-case";

// Simple text obfuscation
function obfuscateText(text) {
  return swapCase(text);
}

console.log(obfuscateText("Secret Message")); // "sECRET mESSAGE"
console.log(obfuscateText("Password123")); // "pASSWORD123"

Alternating Case Effect

import { swapCase } from "text-swap-case";

// Create alternating case effect
function alternatingCase(text) {
  return text
    .split("")
    .map((char, index) =>
      index % 2 === 0 ? char.toLowerCase() : char.toUpperCase(),
    )
    .join("");
}

// Compare with swap case
const original = "Hello World";
console.log("Original:", original); // "Hello World"
console.log("Swap Case:", swapCase(original)); // "hELLO wORLD"
console.log("Alternating:", alternatingCase(original)); // "hElLo WoRlD"

Case Inversion for Testing

import { swapCase } from "text-swap-case";

// Test case sensitivity
function testCaseSensitivity(input) {
  const swapped = swapCase(input);
  return {
    original: input,
    swapped: swapped,
    areEqual: input === swapped,
    length: input.length,
  };
}

console.log(testCaseSensitivity("Hello"));
// {
//   original: "Hello",
//   swapped: "hELLO",
//   areEqual: false,
//   length: 5
// }

Creative Text Effects

import { swapCase } from "text-swap-case";

// Create stylized text
function stylizeText(text, style = "swap") {
  switch (style) {
    case "swap":
      return swapCase(text);
    case "upper":
      return text.toUpperCase();
    case "lower":
      return text.toLowerCase();
    case "title":
      return text.replace(
        /\w\S*/g,
        (txt) => txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase(),
      );
    default:
      return text;
  }
}

const text = "JavaScript Programming";
console.log("Swap:", stylizeText(text, "swap")); // "jAVAsCRIPT pROGRAMMING"
console.log("Upper:", stylizeText(text, "upper")); // "JAVASCRIPT PROGRAMMING"
console.log("Lower:", stylizeText(text, "lower")); // "javascript programming"
console.log("Title:", stylizeText(text, "title")); // "Javascript Programming"

Password Transformation

import { swapCase } from "text-swap-case";

// Transform passwords (for demonstration only)
function transformPassword(password) {
  // Note: This is for demonstration only, not for real security
  return swapCase(password);
}

console.log(transformPassword("MyPassword123")); // "mYpASSWORD123"

Text Processing Pipeline

import { swapCase } from "text-swap-case";

class TextProcessor {
  constructor() {
    this.processors = [];
  }

  addSwapCase() {
    this.processors.push(swapCase);
    return this;
  }

  addReverse() {
    this.processors.push((text) => text.split("").reverse().join(""));
    return this;
  }

  process(text) {
    return this.processors.reduce(
      (result, processor) => processor(result),
      text,
    );
  }
}

const processor = new TextProcessor().addSwapCase().addReverse();

console.log(processor.process("Hello World")); // "DLROw OLLEh"

📖 API Reference

swapCase(input)

Swaps the case of each character in a string.

Parameters

• input (string): The string to transform

Returns

• string: The string with swapped case

📊 Bundle Size

This package is optimized for minimal bundle size:

• Minified: ~200B
• Gzipped: ~150B
• Tree-shakeable: Yes
• Side effects: None

🌍 Browser Support

• Modern browsers: ES2015+ (Chrome 51+, Firefox 54+, Safari 10+)
• Node.js: 12+
• TypeScript: 4.0+
• Bundle formats: UMD, ESM, CommonJS

🧪 Testing

# Run tests
pnpm test

# Run tests in watch mode
pnpm test --watch

# Run tests with coverage
pnpm test --coverage

# Type checking
pnpm typecheck

# Linting
pnpm lint

🔗 Related Packages

• text-camel-case - Convert to camelCase
• text-capital-case - Convert to Capital Case
• text-constant-case - Convert to CONSTANT_CASE
• text-dot-case - Convert to dot.case
• text-header-case - Convert to Header-Case
• text-case - All case transformations in one package

📜 License

MIT © Dmitry Selikhov

🤝 Contributing

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

🆘 Support

• 📧 Email: [email protected]
• 🐛 Issues: GitHub Issues
• 💬 Discussions: GitHub Discussions
• 📖 Documentation: Full Documentation

Made with ❤️ by Dmitry Selikhov