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

📦 Installation

# npm
npm install text-case

# yarn
yarn add text-case

# pnpm
pnpm add text-case

# bun
bun add text-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
  paramCase, // user-profile-data (alias for kebab-case)
  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 Functions

Core Transformations

| Function | Output Example | Description | | ---------------- | ------------------- | -------------------------------------------------- | | camelCase() | userProfileData | First word lowercase, subsequent words capitalized | | pascalCase() | UserProfileData | All words capitalized, no separators | | snakeCase() | user_profile_data | Lowercase words separated by underscores | | kebabCase() | user-profile-data | Lowercase words separated by hyphens | | titleCase() | User Profile Data | All words capitalized, separated by spaces | | sentenceCase() | User profile data | First word capitalized, rest lowercase |

Specialized Formats

| Function | Output Example | Description | | ---------------- | ------------------- | -------------------------------------------- | | constantCase() | USER_PROFILE_DATA | Uppercase words separated by underscores | | dotCase() | user.profile.data | Lowercase words separated by dots | | pathCase() | user/profile/data | Lowercase words separated by forward slashes | | headerCase() | User-Profile-Data | Capitalized words separated by hyphens | | capitalCase() | User Profile Data | All words capitalized, separated by spaces | | noCase() | user profile data | Lowercase words separated by spaces | | paramCase() | user-profile-data | Alias for kebab-case |

Character Transformations

| Function | Output Example | Description | | ------------------ | ------------------- | --------------------------- | | upperCase() | USER PROFILE DATA | All characters uppercase | | lowerCase() | user profile data | All characters lowercase | | upperCaseFirst() | User profile data | First character uppercase | | lowerCaseFirst() | user Profile Data | First character lowercase | | swapCase() | uSER pROFILE dATA | Swap case of all characters |

Validation Utilities

| Function | Output Example | Description | | --------------- | -------------- | ---------------------------- | | isUpperCase() | true/false | Check if string is uppercase | | isLowerCase() | true/false | Check if string is lowercase |

🛠️ 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("[email protected]", {
  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, 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);

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: "[email protected]",
};
const jsUser = Object.fromEntries(
  Object.entries(dbUser).map(([key, value]) => [camelCase(key), value]),
);
// { firstName: "John", lastName: "Doe", emailAddress: "[email protected]" }

// 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"));

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" }

📖 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;
  },
};

📊 Bundle Size

This package is optimized for minimal bundle size:

• Minified: ~8KB (all functions)
• Gzipped: ~3KB (all functions)
• Tree-shakeable: Yes
• Side effects: None

For even smaller bundles, consider using individual packages:

// ❌ 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

🧪 Testing

# Run tests
pnpm test

# Run tests in watch mode
pnpm test --watch

# Run tests with coverage
pnpm test --coverage

🔗 Individual Packages

For optimal bundle size, you can install individual packages:

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

📜 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

Made with ❤️ by Dmitry Selikhov