Normalize Vietnamese

A TypeScript library for Vietnamese text processing including accent normalization, text masking, and string utilities.

Features

• ✅ Vietnamese Accent Normalization: Automatically correct Vietnamese accent placement according to grammar rules
• ✅ Text Masking: Mask sensitive information in strings
• ✅ Text Normalization: Convert text to lowercase, remove special characters
• ✅ TypeScript Support: Full TypeScript definitions included
• ✅ Zero Dependencies: Only requires slugify for text normalization

Installation

# use npm
npm install normalize-vietnamese
# use yarn
yarn add normalize-vietnamese

Usage

Import

import Str from "normalize-vietnamese";
// or
import { Str } from "normalize-vietnamese";

Vietnamese Accent Normalization

The normalizeVietnameseAccent method corrects Vietnamese accent placement according to Vietnamese grammar rules:

// Correct diphthongs (2 vowels) - accent on first vowel
Str.normalizeVietnameseAccent("toà"); // returns 'tòa'
Str.normalizeVietnameseAccent("thuỷ"); // returns 'thủy'

// Correct triphthongs (3 vowels) - accent on second vowel
Str.normalizeVietnameseAccent("tòan"); // returns 'toàn'
Str.normalizeVietnameseAccent("khủyu"); // returns 'khuỷu'

// Exception: ê and ơ have priority regardless of position
Str.normalizeVietnameseAccent("thủơ"); // returns 'thuở'
Str.normalizeVietnameseAccent("chuỵên"); // returns 'chuyện'

// Handle special consonant clusters (gi, qu)
Str.normalizeVietnameseAccent("gìa"); // returns 'già'
Str.normalizeVietnameseAccent("qủa"); // returns 'quả'

// Process multiple words
Str.normalizeVietnameseAccent("tòa nhà toàn"); // returns 'tòa nhà toàn'

Vietnamese Accent Rules

1. Single vowel: Accent stays on the vowel
2. Two vowels (diphthong): Accent on first vowel
3. Three vowels (triphthong): Accent on second vowel
4. Exception: ê and ơ have priority regardless of position
5. Special consonants: gi and qu are treated as single consonants

Text Masking

// Mask entire string
Str.mask("hello"); // returns '*****'

// Mask with start and end positions
Str.mask("hello", 1, 4); // returns 'h***o'

// Negative positions (from end)
Str.mask("hello", -2, 4); // returns 'hel*o'
Str.mask("hello", 1, -1); // returns 'h***o'

Text Normalization

// Convert to lowercase, remove special characters
Str.normalize("Hello World!"); // returns 'hello world'

// Handles Vietnamese characters
Str.normalize("Xin chào thế giới!"); // returns 'xin chao the gioi'

API Reference

Str.normalizeVietnameseAccent(text: string): string

Normalizes Vietnamese accent marks according to Vietnamese grammar rules.

• Parameters: text - The text to normalize
• Returns: The normalized text with proper accent placement
• Throws: Returns original input if not a string

Str.mask(text: string, start?: number, end?: number): string

Masks part of a string with asterisks.

• Parameters:
  • text - The text to mask
  • start - Start position (default: 0, supports negative values)
  • end - End position (default: 0, supports negative values)
• Returns: The masked string
• Throws: Returns original text for invalid parameters

Str.normalize(text: string): string

Normalizes text by converting to lowercase and removing special characters.

• Parameters: text - The text to normalize
• Returns: The normalized text
• Throws: Returns original input if not a string

Development

Setup

git clone https://github.com/nvminh461/normalize-vietnamese
cd normalize-vietnamese
npm install

Scripts

# Build the library
npm run build

# Run tests
npm test

# Run tests in watch mode
npm run test:watch

# Generate test coverage
npm run test:coverage

# Development mode (watch for changes)
npm run dev

Testing

The library includes comprehensive tests covering all functionality:

npm test

Requirements

• Node.js >= 14.0.0
• TypeScript >= 4.0.0 (for development)

License

MIT

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

Changelog

1.0.0

• Initial release
• Vietnamese accent normalization
• Text masking functionality
• Text normalization utilities
• Full TypeScript support