Snake Case

[![NPM version][npm-image]][npm-url]
[![NPM downloads][downloads-image]][downloads-url]
[![Bundle size][bundlephobia-image]][bundlephobia-url]

> Transform text into snake_case format where words are lowercase and separated by underscores.

🚀 Features

- Lightweight - Only ~450B 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
- Customizable - Flexible options for advanced use cases

📦 Installation

``bash


npm

npm install text-snake-case

yarn

yarn add text-snake-case

pnpm

pnpm add text-snake-case

bun

bun add text-snake-case
`

🎯 Quick Start

`javascript
import { snakeCase } from "text-snake-case";

console.log(snakeCase("hello world")); // "hello_world"
console.log(snakeCase("userProfileData")); // "user_profile_data"
console.log(snakeCase("backgroundColor")); // "background_color"
`

📖 Usage

$3

`javascript
import { snakeCase } from "text-snake-case";

console.log(snakeCase("hello world")); // "hello_world"
`

$3

`javascript
const { snakeCase } = require("text-snake-case");

console.log(snakeCase("hello world")); // "hello_world"
`

$3

`typescript
import { snakeCase, snakeCaseTransformMerge, Options } from "text-snake-case";

const result: string = snakeCase("hello world");
console.log(result); // "hello_world"
`

🔄 Transformation Examples

$3

`javascript
import { snakeCase } from "text-snake-case";

// From different cases
snakeCase("hello world"); // "hello_world"
snakeCase("Hello World"); // "hello_world"
snakeCase("HELLO WORLD"); // "hello_world"
snakeCase("camelCase"); // "camel_case"
snakeCase("PascalCase"); // "pascal_case"
snakeCase("kebab-case"); // "kebab_case"
snakeCase("dot.case"); // "dot_case"
snakeCase("CONSTANT_CASE"); // "constant_case"

// Complex examples
snakeCase("XMLHttpRequest"); // "xml_http_request"
snakeCase("iPhone"); // "i_phone"
snakeCase("version 1.2.3"); // "version_1_2_3"
snakeCase("userProfileData"); // "user_profile_data"
`

$3

`javascript
import { snakeCase, snakeCaseTransformMerge } from "text-snake-case";

// Custom transform to merge numbers without separator
snakeCase("version 1.2.3", {
transform: snakeCaseTransformMerge,
}); // "version_123"

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

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

// Custom transformation function
snakeCase("API-v2-endpoint", {
transform: (word, index) => {
if (word === "API") return "api";
if (word === "v2") return "v2";
return word.toLowerCase();
},
}); // "api_v2_endpoint"
`

🌍 Real-World Examples

$3

`javascript
import { snakeCase } from "text-snake-case";

// Table columns
snakeCase("firstName"); // "first_name"
snakeCase("emailAddress"); // "email_address"
snakeCase("createdAt"); // "created_at"
snakeCase("userId"); // "user_id"
snakeCase("accessToken"); // "access_token"
`

$3

`javascript
import { snakeCase } from "text-snake-case";

// REST API fields
snakeCase("userProfile"); // "user_profile"
snakeCase("lastLoginDate"); // "last_login_date"
snakeCase("isActive"); // "is_active"
snakeCase("paymentMethod"); // "payment_method"
snakeCase("shippingAddress"); // "shipping_address"
`

$3

`javascript
import { snakeCase } from "text-snake-case";

// Environment variable names
snakeCase("databaseUrl"); // "database_url"
snakeCase("apiKey"); // "api_key"
snakeCase("maxRetries"); // "max_retries"
snakeCase("timeoutMs"); // "timeout_ms"
snakeCase("debugMode"); // "debug_mode"
`

$3

`javascript
import { snakeCase } from "text-snake-case";

// Transform object keys from camelCase to snake_case
const jsUser = {
firstName: "John",
lastName: "Doe",
emailAddress: "john@example.com",
createdAt: "2023-01-01",
};

const dbUser = Object.fromEntries(
Object.entries(jsUser).map(([key, value]) => [snakeCase(key), value]),
);

console.log(dbUser);
// {
// first_name: "John",
// last_name: "Doe",
// email_address: "john@example.com",
// created_at: "2023-01-01"
// }
`

📖 API Reference

$3

Converts a string to snake_case.

#### Parameters

- input (string): The string to convert
- options (Options, optional): Configuration options

#### Returns

- string: The snake_case formatted string

#### Options

`typescript
interface Options {
// Custom transform function for word processing
transform?: (word: string, index: number, words: string[]) => string;

// Regex to strip characters before processing
stripRegexp?: RegExp;

// Custom split function
split?: (value: string) => string[];
}
`

$3

A transform function that merges numeric characters without separation.

`javascript
import { snakeCase, snakeCaseTransformMerge } from "text-snake-case";

snakeCase("version 1.2.3", { transform: snakeCaseTransformMerge }); // "version_123"
`

🔧 Advanced Configuration

$3

`javascript
import { snakeCase } from "text-snake-case";

// Split on specific patterns
snakeCase("XMLHttpRequest", {
splitRegexp: /([a-z])([A-Z])/g,
}); // "xml_http_request"

// Split on numbers
snakeCase("user123data", {
splitRegexp: /([a-zA-Z])(\d)/g,
}); // "user_123_data"
`

$3

`javascript
import { snakeCase } from "text-snake-case";

// Strip specific characters
snakeCase("hello@world.com", {
stripRegexp: /[@.]/g,
}); // "hello_world_com"

// Strip all non-alphanumeric
snakeCase("hello!@#world", {
stripRegexp: /[^a-zA-Z0-9]/g,
}); // "hello_world"
`

$3

`javascript
import { snakeCase } from "text-snake-case";

// Preserve specific formatting
snakeCase("XML-HTTP-Request", {
transform: (word, index) => {
const acronyms = ["xml", "http", "api", "url"];
if (acronyms.includes(word.toLowerCase())) {
return word.toLowerCase();
}
return word.toLowerCase();
},
}); // "xml_http_request"

// Custom business logic
snakeCase("UserV2API", {
transform: (word, index) => {
if (word === "V2") return "v2";
if (word === "API") return "api";
return word.toLowerCase();
},
}); // "user_v2_api"
`

📊 Bundle Size

This package is optimized for minimal bundle size:

- Minified: ~450B
- Gzipped: ~250B
- 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

`bash


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: selikhov.dmitrey@gmail.com
- 🐛 Issues: GitHub Issues
- 💬 Discussions: GitHub Discussions
- 📖 Documentation: Full Documentation

---

Made with ❤️ by Dmitry Selikhov

[npm-image]: https://img.shields.io/npm/v/text-snake-case.svg?style=flat
[npm-url]: https://npmjs.org/package/text-snake-case
[downloads-image]: https://img.shields.io/npm/dm/text-snake-case.svg?style=flat
[downloads-url]: https://npmjs.org/package/text-snake-case
[bundlephobia-image]: https://img.shields.io/bundlephobia/minzip/text-snake-case.svg
[bundlephobia-url]: https://bundlephobia.com/result?p=text-snake-case