@lacspace/money

Money without the floating-point bugs — integer cents, safe math, localized formatting.

0.1 + 0.2 !== 0.3 — so never store money as a float. @lacspace/money keeps amounts as integer minor units, refuses to add different currencies, splits a bill without losing a cent, and formats with Intl. Tiny, typed, isomorphic.

Install

npm i @lacspace/money

Use it

import { money, Money } from "@lacspace/money";

const price = money(19.99, "USD");   // 1999 minor units, exact
price.multiply(3).format();          // "$59.97"
price.add(money(5, "USD"));          // $24.99
money(9.99, "USD").add(money(1, "EUR")); // ❌ throws: currency mismatch

// Split a bill three ways — the cent doesn't vanish
money(10, "USD").allocate([1, 1, 1]).map((m) => m.format());
// ["$3.34", "$3.33", "$3.33"]   (sum is exactly $10.00)

// Zero-decimal & 3-decimal currencies handled automatically
money(1000, "JPY").format("ja-JP"); // "￥1,000"
money(1.5, "BHD").toMinor();        // 1500  (BHD has 3 decimals)

Note on Money.parse(): parsing is best-effort and locale-agnostic. It can misread strings where the thousands and decimal separators are ambiguous — e.g. "1,234" is read as 1.234 (a decimal), not 1234. For untrusted or locale-specific input, prefer constructing from an explicit numeric amount (Money.of / Money.fromMinor) rather than relying on parse().

Why minor units

Money.fromMinor(1999, "USD");   // exact, no rounding surprises
Money.of(19.99, "USD");         // convenience: rounds major → minor once
money(19.99, "USD").toMinor();  // 1999

API

| | | | --- | --- | | money(major, ccy) / Money.of / Money.fromMinor / Money.zero / Money.parse | construct | | .add · .subtract · .multiply · .divide · .negate · .abs | arithmetic (currency-checked) | | .allocate(ratios) · .split(n) | remainder-preserving distribution | | .equals · .greaterThan · .lessThan · .greaterThanOrEqual · .lessThanOrEqual | compare | | .isZero · .isPositive · .isNegative | predicates | | .format(locale?, opts?) · .toString · .toMajor · .toMinor · .toJSON | output | | sumMoney(list, ccy?) · decimalsFor(ccy) | helpers |

All operations return a new Money — instances are immutable.

Licensing

Free under the Lacspace Free Licence — MIT-equivalent freedoms. Use it in personal and commercial projects at no cost; just keep the notice. See the Lacspace Licence Centre.

Part of the Lacspace ecosystem — zero-dependency, isomorphic TypeScript packages.

All packages ↗ · npm org ↗ · Licence Centre ↗ · GitHub ↗