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)

1# npm
2npm install text-case
3
4# yarn
5yarn add text-case
6
7# pnpm
8pnpm add text-case
9
10# bun
11bun add text-case

Individual packages

1# Install only what you need
2npm install text-camel-case text-kebab-case text-snake-case

🎯 Quick Start

1import {
2  camelCase, // userProfileData
3  pascalCase, // UserProfileData
4  kebabCase, // user-profile-data
5  snakeCase, // user_profile_data
6  titleCase, // User Profile Data
7  sentenceCase, // User profile data
8  constantCase, // USER_PROFILE_DATA
9  dotCase, // user.profile.data
10  pathCase, // user/profile/data
11  headerCase, // User-Profile-Data
12  capitalCase, // User Profile Data
13  noCase, // user profile data
14  upperCase, // USER PROFILE DATA
15  lowerCase, // user profile data
16  upperCaseFirst, // User profile data
17  lowerCaseFirst, // user Profile Data
18  swapCase, // uSER pROFILE dATA
19  isUpperCase, // Boolean check
20  isLowerCase, // Boolean check
21} from "text-case";
22
23// Transform any text format
24const input = "user_profile_data";
25
26console.log(camelCase(input)); // "userProfileData"
27console.log(pascalCase(input)); // "UserProfileData"
28console.log(kebabCase(input)); // "user-profile-data"
29console.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:

1import { camelCase, snakeCase } from "text-case";
2
3// Custom word splitting
4camelCase("XMLHttpRequest", {
5  splitRegexp: /([a-z])([A-Z])/g,
6}); // "xmlHttpRequest"
7
8// Custom character stripping
9snakeCase("hello@world.com", {
10  stripRegexp: /[@.]/g,
11}); // "hello_world_com"
12
13// Custom transformations
14camelCase("api-v2-endpoint", {
15  transform: (word, index) => {
16    if (word === "api") return "API";
17    if (word === "v2") return "V2";
18    return word;
19  },
20}); // "APIV2Endpoint"

TypeScript Support

Full TypeScript support with comprehensive type definitions:

1import { camelCase, PascalCase, Options } from "text-case";
2
3// Type-safe options
4const options: Options = {
5  splitRegexp: /([a-z])([A-Z])/g,
6  stripRegexp: /[^a-zA-Z0-9]/g,
7  transform: (word: string, index: number, words: string[]) =>
8    word.toLowerCase(),
9};
10
11// Type inference
12const result: string = camelCase("hello-world", options);
13
14// Generic type support for consistent transformations
15function transformKeys<T extends Record<string, any>>(
16  obj: T,
17  transformer: (key: string) => string,
18): Record<string, T[keyof T]> {
19  return Object.fromEntries(
20    Object.entries(obj).map(([key, value]) => [transformer(key), value]),
21  );
22}
23
24const data = { user_name: "John", email_address: "john@example.com" };
25const camelData = transformKeys(data, camelCase);
26// { userName: "John", emailAddress: "john@example.com" }

Real-World Examples

API Development

1import { camelCase, snakeCase, kebabCase } from "text-case";
2
3// Convert database columns to JavaScript
4const dbUser = {
5  first_name: "John",
6  last_name: "Doe",
7  email_address: "john@example.com",
8};
9const jsUser = Object.fromEntries(
10  Object.entries(dbUser).map(([key, value]) => [camelCase(key), value]),
11);
12// { firstName: "John", lastName: "Doe", emailAddress: "john@example.com" }
13
14// Generate API endpoints
15const createEndpoint = (resource, action) =>
16  `/api/${kebabCase(resource)}/${kebabCase(action)}`;
17
18createEndpoint("UserProfile", "GetById"); // "/api/user-profile/get-by-id"

React Development

1import { pascalCase, camelCase } from "text-case";
2
3// Component generation
4const createComponent = (name) => `
5  import React from 'react';
6
7  interface ${pascalCase(name)}Props {
8    ${camelCase(name)}Data?: any;
9  }
10
11  export const ${pascalCase(name)}: React.FC<${pascalCase(name)}Props> = ({ ${camelCase(name)}Data }) => {
12    return <div>{/* ${pascalCase(name)} component */}</div>;
13  };
14`;
15
16console.log(createComponent("user_profile_card"));

CSS-in-JS

1import { camelCase } from "text-case";
2
3// Convert CSS properties
4const cssToJS = (cssText) => {
5  return cssText.replace(
6    /([a-z])-([a-z])/g,
7    (match, p1, p2) => p1 + p2.toUpperCase(),
8  );
9};
10
11const styles = {
12  backgroundColor: "#fff", // from background-color
13  fontSize: "16px", // from font-size
14  marginTop: "10px", // from margin-top
15};

Configuration Management

1import { constantCase, camelCase } from "text-case";
2
3// Environment variables to config object
4const envToConfig = (envVars) => {
5  return Object.fromEntries(
6    Object.entries(envVars)
7      .filter(([key]) => key.startsWith("APP_"))
8      .map(([key, value]) => [camelCase(key.replace("APP_", "")), value]),
9  );
10};
11
12const env = {
13  APP_DATABASE_URL: "postgres://...",
14  APP_API_SECRET_KEY: "secret123",
15  APP_MAX_FILE_SIZE: "10MB",
16};
17
18const config = envToConfig(env);
19// { databaseUrl: "postgres://...", apiSecretKey: "secret123", maxFileSize: "10MB" }

🏗️ Framework Integration

Express.js

1import express from "express";
2import { kebabCase } from "text-case";
3
4const app = express();
5
6// Auto-generate kebab-case routes
7const createRoute = (name, handler) => {
8  app.get(`/${kebabCase(name)}`, handler);
9};
10
11createRoute("getUserProfile", (req, res) => res.json({ profile: {} }));
12// Creates route: GET /get-user-profile

Next.js

1// pages/[...slug].js
2import { pathCase } from "text-case";
3
4export async function getStaticPaths() {
5  const pages = ["About Us", "Contact Form", "Privacy Policy"];
6
7  return {
8    paths: pages.map((page) => ({
9      params: { slug: pathCase(page).split("/") },
10    })),
11    fallback: false,
12  };
13}

Vue.js

1import { pascalCase } from "text-case";
2
3// Dynamic component registration
4const components = ["UserCard", "ProductList", "CheckoutForm"];
5
6components.forEach((name) => {
7  app.component(pascalCase(name), () => import(`./components/${name}.vue`));
8});

🧪 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

1# Run all tests
2pnpm test
3
4# Run tests for specific package
5pnpm --filter text-camel-case test
6
7# Run tests with coverage
8pnpm test --coverage
9
10# Run tests in watch mode
11pnpm 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:

1// ❌ Imports entire library (~8KB)
2import { camelCase } from "text-case";
3
4// ✅ Imports only camelCase (~450B)
5import { 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

1interface Options {
2  // RegExp to split input into words
3  splitRegexp?: RegExp;
4
5  // RegExp to strip unwanted characters
6  stripRegexp?: RegExp;
7
8  // Custom word transformation function
9  transform?: (word: string, index: number, words: string[]) => string;
10
11  // Custom split function (alternative to splitRegexp)
12  split?: (value: string) => string[];
13
14  // Delimiter between words (for spaced formats)
15  delimiter?: string;
16}

Common Patterns

1// Split on camelCase and PascalCase boundaries
2const camelSplit = { splitRegexp: /([a-z])([A-Z])/g };
3
4// Preserve numbers as separate words
5const numberSplit = { splitRegexp: /([a-zA-Z])(\d)/g };
6
7// Strip special characters
8const stripSpecial = { stripRegexp: /[^a-zA-Z0-9]/g };
9
10// Custom acronym handling
11const acronymTransform = {
12  transform: (word) => {
13    const acronyms = ["API", "URL", "HTTP", "JSON", "XML"];
14    return acronyms.includes(word.toUpperCase()) ? word.toUpperCase() : word;
15  },
16};

🤝 Contributing

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

Development Setup

1# Clone the repository
2git clone https://github.com/idimetrix/text-case.git
3cd text-case
4
5# Install dependencies
6pnpm install
7
8# Build all packages
9pnpm build
10
11# Run tests
12pnpm test
13
14# Type check
15pnpm typecheck
16
17# Lint code
18pnpm 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