bahtread 🇹🇭

A highly robust, modern, and lightweight TypeScript library to convert numbers into Thai words and Thai Baht currency text format.

Features

• Thai Baht Currency Formatting: Converts numbers/strings (e.g. 852,500) to Thai Baht text ("แปดแสนห้าหมื่นสองพันห้าร้อยบาทถ้วน").
• Plain Thai Numbers Formatting: Converts numbers/strings (e.g. 123.45) to plain Thai text ("หนึ่งร้อยยี่สิบสามจุดสี่ห้า").
• Arbitrary Precision (BigInt support): Safe from floating-point overflow for extremely large values.
• Auto-rounding: Correctly rounds currency decimal values (Satang) to 2 decimal places.
• Negative Numbers: Supports negative values by prefixing with "ลบ".
• Zero-Dependency: Extremely lightweight.
• ESM & CJS Support: Built with dual package format exports and full type definitions.

Installation

npm install bahtread

Usage

1. Thai Baht Conversion (thaiBaht)

Converts a number or string containing numeric digits (commas are automatically cleaned) into formal Thai Baht currency text.

import { thaiBaht } from 'bahtread';

// Basic usage
console.log(thaiBaht(852500)); 
// Output: "แปดแสนห้าหมื่นสองพันห้าร้อยบาทถ้วน"

// With decimal / Satang
console.log(thaiBaht('1,234,567.89')); 
// Output: "หนึ่งล้านสองแสนสามหมื่นสี่พันห้าร้อยหกสิบเจ็ดบาทแปดสิบเก้าสตางค์"

// Negative values
console.log(thaiBaht(-10.50)); 
// Output: "ลบสิบบาทห้าสิบสตางค์"

// Decimals automatic rounding (to 2 decimal places)
console.log(thaiBaht(1.234)); // Output: "หนึ่งบาทยี่สิบสามสตางค์"
console.log(thaiBaht(1.235)); // Output: "หนึ่งบาทยี่สิบสี่สตางค์"

// String inputs support commas, plus sign, leading/trailing dots
console.log(thaiBaht('1,234,567.89')); // commas ignored
console.log(thaiBaht('+100.50'));      // leading plus ok
console.log(thaiBaht('.25'));          // → "ยี่สิบห้าสตางค์"
console.log(thaiBaht('100.'));         // → "หนึ่งร้อยบาทถ้วน"

2. Thai Plain Reading (thaiRead)

Converts a number or numeric string to plain Thai reading text, with decimals read digit-by-digit.

import { thaiRead } from 'bahtread';

console.log(thaiRead(123)); 
// Output: "หนึ่งร้อยยี่สิบสาม"

console.log(thaiRead(123.45)); 
// Output: "หนึ่งร้อยยี่สิบสามจุดสี่ห้า"

console.log(thaiRead(-1000001)); 
// Output: "ลบหนึ่งล้านเอ็ด"

Rounding Policy

thaiBaht rounds half-up at the 2nd decimal place (satang):

| Input | JS binary (IEEE 754) | Math.round(n × 100) | Output | |-------|---------------------|------------------------|--------| | 0.001 | → 0.001 | → 0 | ศูนย์บาทถ้วน | | 0.004 | → 0.004 | → 0 | ศูนย์บาทถ้วน | | 0.005 | → 0.005 | → 1 | หนึ่งสตางค์ | | 1.234 | → 1.234 | → 123 | ยี่สิบสามสตางค์ | | 1.235 | → 1.235 | → 124 | ยี่สิบสี่สตางค์ | | 1.999 | → 1.999 | → 200 | สองบาทถ้วน (integer carries) |

⚠️ Large numbers: For values above Number.MAX_SAFE_INTEGER (~9 quadrillion), use string input to avoid precision loss:

// ✅ correct — string preserves all digits
thaiBaht('9999999999999999.99')

// ❌ wrong — number loses precision
thaiBaht(9999999999999999.99)

This also applies to thaiRead for very long decimal values.

Supported Input Formats

parseInput accepts flexible numeric string representations:

| Format | Example | Behavior | |--------|---------|----------| | Plain number | '123' | standard | | Commas | '1,234,567.89' | commas stripped | | Whitespace | ' 100 ' | trimmed | | Leading + | '+100' | stripped | | Leading dot | '.5' | → '0.5' | | Trailing dot | '100.' | → '100' | | Negative dot | '-.5' | → '-0.5' | | Leading zeros | '000123' | stripped |