Text Case

NPM version NPM downloads Bundle size License: MIT TypeScript

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

📦 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("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, 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: "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"));

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:

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

🧪 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:

📜 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

Made with ❤️ by Dmitry Selikhov