@pfarr.tools/romanize

Converts positive integers to Roman numeral strings.

Installation

npm install @pfarr.tools/romanize

Usage

ESM

import { romanize } from '@pfarr.tools/romanize';

romanize(1);    // 'I'
romanize(4);    // 'IV'
romanize(9);    // 'IX'
romanize(1994); // 'MCMXCIV'
romanize(2024); // 'MMXXIV'
romanize('X');  // NaN

CommonJS

const { romanize } = require('@pfarr.tools/romanize');

Default export

import romanize from '@pfarr.tools/romanize';

API

`romanize(num)`

Parameter	Type	Description
`num`	`number \| string`	A positive integer (or numeric string) to convert.

Returns string — the Roman numeral representation, or NaN if num is not a valid number.

Supported range

1 to 3 999 999 (outputs become increasingly unwieldy beyond 3 999 due to the unbounded M prefix, but the function never throws).

Subtractive notation

The standard subtractive pairs are used: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900).

Examples

romanize(42);   // 'XLII'
romanize(99);   // 'XCIX'
romanize(399);  // 'CCCXCIX'
romanize(1776); // 'MDCCLXXVI'
romanize(3999); // 'MMMCMXCIX'