Text Case

The ultimate text case transformation library for JavaScript and TypeScript. Convert text between camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE, Title Case, Sentence case, dot.case, path/case, Header-Case, and many more formats with comprehensive TypeScript support.

🚀 Features

• 21 case transformation functions covering all common text formatting needs
• Type-safe with comprehensive TypeScript definitions
• Zero dependencies - lightweight and fast
• Tree-shakeable - import only what you need
• Universal - works in browsers, Node.js, and serverless environments
• Comprehensive testing - 100% test coverage with extensive edge cases
• Professional documentation - detailed examples and API references
• Modern tooling - ES modules, CommonJS, and UMD support
• Monorepo architecture - individual packages for optimal bundle size

📦 Installation

All packages (recommended)

# npm
npm install text-case

# yarn
yarn add text-case

# pnpm
pnpm add text-case

# bun
bun add text-case

Individual packages

# Install only what you need
npm install text-camel-case text-kebab-case text-snake-case

🎯 Quick Start

import {
  camelCase, // userProfileData
  pascalCase, // UserProfileData
  kebabCase, // user-profile-data
  snakeCase, // user_profile_data
  titleCase, // User Profile Data
  sentenceCase, // User profile data
  constantCase, // USER_PROFILE_DATA
  dotCase, // user.profile.data
  pathCase, // user/profile/data
  headerCase, // User-Profile-Data
  capitalCase, // User Profile Data
  noCase, // user profile data
  upperCase, // USER PROFILE DATA
  lowerCase, // user profile data
  upperCaseFirst, // User profile data
  lowerCaseFirst, // user Profile Data
  swapCase, // uSER pROFILE dATA
  isUpperCase, // Boolean check
  isLowerCase, // Boolean check
} from "text-case";

// Transform any text format
const input = "user_profile_data";

console.log(camelCase(input)); // "userProfileData"
console.log(pascalCase(input)); // "UserProfileData"
console.log(kebabCase(input)); // "user-profile-data"
console.log(titleCase(input)); // "User Profile Data"

📚 Available Packages

Core Transformations

Package	Output Example	Use Cases	Size	NPM
text-camel-case	userProfileData	JavaScript variables, object properties	~450B
text-pascal-case	UserProfileData	Class names, components, types	~400B
text-snake-case	user_profile_data	Database columns, Python variables	~300B
text-kebab-case	user-profile-data	CSS classes, URLs, HTML attributes	~350B
text-title-case	User Profile Data	Headers, titles, proper nouns	~350B
text-sentence-case	User profile data	Sentences, descriptions	~320B

Specialized Formats

Package	Output Example	Use Cases	Size	NPM
text-constant-case	USER_PROFILE_DATA	Environment variables, constants	~380B
text-dot-case	user.profile.data	Object paths, file names	~280B
text-path-case	user/profile/data	File paths, URLs	~300B
text-header-case	User-Profile-Data	HTTP headers, train-case	~340B
text-capital-case	User Profile Data	Business titles, formal text	~330B
text-no-case	user profile data	Search queries, plain text	~280B
text-param-case	user-profile-data	URL parameters, kebab-case alias	~350B

Character Transformations

Package	Output Example	Use Cases	Size	NPM
text-upper-case	USER PROFILE DATA	Constants, emphasis	~120B
text-lower-case	user profile data	Normalization, search	~120B
text-upper-case-first	User profile data	Sentences, proper formatting	~130B
text-lower-case-first	user Profile Data	camelCase conversion	~130B
text-swap-case	uSER pROFILE dATA	Creative text, obfuscation	~140B

Validation Utilities

Package	Output Example	Use Cases	Size	NPM
text-is-upper-case	true/false	Input validation, conditionals	~100B
text-is-lower-case	true/false	Input validation, conditionals	~100B

🛠️ Advanced Usage

Custom Options

All transformation functions accept an optional second parameter for customization:

import { camelCase, snakeCase } from "text-case";

// Custom word splitting
camelCase("XMLHttpRequest", {
  splitRegexp: /([a-z])([A-Z])/g,
}); // "xmlHttpRequest"

// Custom character stripping
snakeCase("hello@world.com", {
  stripRegexp: /[@.]/g,
}); // "hello_world_com"

// Custom transformations
camelCase("api-v2-endpoint", {
  transform: (word, index) => {
    if (word === "api") return "API";
    if (word === "v2") return "V2";
    return word;
  },
}); // "APIV2Endpoint"

TypeScript Support

Full TypeScript support with comprehensive type definitions:

import { camelCase, PascalCase, Options } from "text-case";

// Type-safe options
const options: Options = {
  splitRegexp: /([a-z])([A-Z])/g,
  stripRegexp: /[^a-zA-Z0-9]/g,
  transform: (word: string, index: number, words: string[]) =>
    word.toLowerCase(),
};

// Type inference
const result: string = camelCase("hello-world", options);

// Generic type support for consistent transformations
function transformKeys<T extends Record<string, any>>(
  obj: T,
  transformer: (key: string) => string,
): Record<string, T[keyof T]> {
  return Object.fromEntries(
    Object.entries(obj).map(([key, value]) => [transformer(key), value]),
  );
}

const data = { user_name: "John", email_address: "john@example.com" };
const camelData = transformKeys(data, camelCase);
// { userName: "John", emailAddress: "john@example.com" }

Real-World Examples

API Development

import { camelCase, snakeCase, kebabCase } from "text-case";

// Convert database columns to JavaScript
const dbUser = {
  first_name: "John",
  last_name: "Doe",
  email_address: "john@example.com",
};
const jsUser = Object.fromEntries(
  Object.entries(dbUser).map(([key, value]) => [camelCase(key), value]),
);
// { firstName: "John", lastName: "Doe", emailAddress: "john@example.com" }

// Generate API endpoints
const createEndpoint = (resource, action) =>
  `/api/${kebabCase(resource)}/${kebabCase(action)}`;

createEndpoint("UserProfile", "GetById"); // "/api/user-profile/get-by-id"

React Development

import { pascalCase, camelCase } from "text-case";

// Component generation
const createComponent = (name) => `
  import React from 'react';

  interface ${pascalCase(name)}Props {
    ${camelCase(name)}Data?: any;
  }

  export const ${pascalCase(name)}: React.FC<${pascalCase(name)}Props> = ({ ${camelCase(name)}Data }) => {
    return <div>{/* ${pascalCase(name)} component */}</div>;
  };
`;

console.log(createComponent("user_profile_card"));

CSS-in-JS

import { camelCase } from "text-case";

// Convert CSS properties
const cssToJS = (cssText) => {
  return cssText.replace(
    /([a-z])-([a-z])/g,
    (match, p1, p2) => p1 + p2.toUpperCase(),
  );
};

const styles = {
  backgroundColor: "#fff", // from background-color
  fontSize: "16px", // from font-size
  marginTop: "10px", // from margin-top
};

Configuration Management

import { constantCase, camelCase } from "text-case";

// Environment variables to config object
const envToConfig = (envVars) => {
  return Object.fromEntries(
    Object.entries(envVars)
      .filter(([key]) => key.startsWith("APP_"))
      .map(([key, value]) => [camelCase(key.replace("APP_", "")), value]),
  );
};

const env = {
  APP_DATABASE_URL: "postgres://...",
  APP_API_SECRET_KEY: "secret123",
  APP_MAX_FILE_SIZE: "10MB",
};

const config = envToConfig(env);
// { databaseUrl: "postgres://...", apiSecretKey: "secret123", maxFileSize: "10MB" }

🏗️ Framework Integration

Express.js

import express from "express";
import { kebabCase } from "text-case";

const app = express();

// Auto-generate kebab-case routes
const createRoute = (name, handler) => {
  app.get(`/${kebabCase(name)}`, handler);
};

createRoute("getUserProfile", (req, res) => res.json({ profile: {} }));
// Creates route: GET /get-user-profile

Next.js

// pages/[...slug].js
import { pathCase } from "text-case";

export async function getStaticPaths() {
  const pages = ["About Us", "Contact Form", "Privacy Policy"];

  return {
    paths: pages.map((page) => ({
      params: { slug: pathCase(page).split("/") },
    })),
    fallback: false,
  };
}

Vue.js

import { pascalCase } from "text-case";

// Dynamic component registration
const components = ["UserCard", "ProductList", "CheckoutForm"];

components.forEach((name) => {
  app.component(pascalCase(name), () => import(`./components/${name}.vue`));
});

🧪 Testing

Each package includes comprehensive test suites with:

• Basic transformations - Standard use cases
• Edge cases - Empty strings, special characters, unicode
• Complex inputs - Mixed cases, numbers, symbols
• Performance tests - Large string handling
• Error handling - Null/undefined inputs
• Real-world scenarios - Practical examples

Running Tests

# Run all tests
pnpm test

# Run tests for specific package
pnpm --filter text-camel-case test

# Run tests with coverage
pnpm test --coverage

# Run tests in watch mode
pnpm test --watch

📊 Bundle Size Comparison

Package	Minified	Gzipped	Tree-shakeable
text-case (all)	~8KB	~3KB	✅
Individual packages	100B-450B	50B-250B	✅

Import only what you need for optimal bundle size:

// ❌ Imports entire library (~8KB)
import { camelCase } from "text-case";

// ✅ Imports only camelCase (~450B)
import { camelCase } from "text-camel-case";

🌍 Browser Support

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

📖 API Reference

Options Interface

interface Options {
  // RegExp to split input into words
  splitRegexp?: RegExp;

  // RegExp to strip unwanted characters
  stripRegexp?: RegExp;

  // Custom word transformation function
  transform?: (word: string, index: number, words: string[]) => string;

  // Custom split function (alternative to splitRegexp)
  split?: (value: string) => string[];

  // Delimiter between words (for spaced formats)
  delimiter?: string;
}

Common Patterns

// Split on camelCase and PascalCase boundaries
const camelSplit = { splitRegexp: /([a-z])([A-Z])/g };

// Preserve numbers as separate words
const numberSplit = { splitRegexp: /([a-zA-Z])(\d)/g };

// Strip special characters
const stripSpecial = { stripRegexp: /[^a-zA-Z0-9]/g };

// Custom acronym handling
const acronymTransform = {
  transform: (word) => {
    const acronyms = ["API", "URL", "HTTP", "JSON", "XML"];
    return acronyms.includes(word.toUpperCase()) ? word.toUpperCase() : word;
  },
};

🤝 Contributing

We welcome contributions! Please see our Contributing Guide for details.

Development Setup

# Clone the repository
git clone https://github.com/idimetrix/text-case.git
cd text-case

# Install dependencies
pnpm install

# Build all packages
pnpm build

# Run tests
pnpm test

# Type check
pnpm typecheck

# Lint code
pnpm lint

Deployment Steps

npx lerna version patch --yes --force-publish=*
npx lerna publish from-package --yes

Package Structure

packages/
├── camel-case/          # camelCase transformation
├── pascal-case/         # PascalCase transformation
├── snake-case/          # snake_case transformation
├── kebab-case/          # kebab-case transformation
├── title-case/          # Title Case transformation
├── sentence-case/       # Sentence case transformation
├── constant-case/       # CONSTANT_CASE transformation
├── dot-case/            # dot.case transformation
├── path-case/           # path/case transformation
├── header-case/         # Header-Case transformation
├── capital-case/        # Capital Case transformation
├── no-case/             # no case transformation
├── param-case/          # param-case transformation
├── upper-case/          # UPPER CASE transformation
├── lower-case/          # lower case transformation
├── upper-case-first/    # Upper case first transformation
├── lower-case-first/    # lower case first transformation
├── swap-case/           # sWaP cAsE transformation
├── is-upper-case/       # UPPER CASE validation
└── is-lower-case/       # lower case validation

📜 License

MIT © Dmitry Selikhov

🆘 Support

• 📧 Email: selikhov.dmitrey@gmail.com
• 🐛 Issues: GitHub Issues
• 💬 Discussions: GitHub Discussions
• 📖 Documentation: Individual package READMEs

🔗 Related Projects

• change-case - The original inspiration
• lodash - Utility library with some case functions
• just - Functional programming utilities

🏆 Why Choose Text Case?

• 🎯 Focused: Specialized in text case transformations
• 📦 Modular: Use only what you need
• 🔒 Reliable: Extensively tested and battle-tested
• ⚡ Fast: Optimized for performance
• 🛡️ Type-safe: Full TypeScript support
• 📚 Well-documented: Comprehensive guides and examples
• 🔄 Consistent: Uniform API across all packages
• 🌟 Modern: Built with modern JavaScript standards

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Made with ❤️ by Dmitry Selikhov