money-fns is a zero-dependency Money library built with BigInt and an FP-oriented design.

This package is side-effect free and is only 679 Bytes when gzipped and minified. Compare with other packages on Bundlephobia.

Installation

NPM:

npm i money-fns

Yarn:

yarn add money-fns

Usage

import {
  addAmounts,
  compareAmount,
  discountAmount,
  floatToAmount,
  formatAmount,
  isAmountNegative,
  isAmountPositive,
  isAmountZero,
  isValidAmount,
  multiplyAmount,
  scaleAmount,
  subtractAmount,
  sumAmounts,
} from "money-fns";

addAmounts("1.00", "2.00"); // '3.00'
subtractAmount("3.00", "2.00"); // '1.00'
multiplyAmount("5.00", "1.15"); // '5.75'
scaleAmount("5.00", 3n); // '15.00'

floatToAmount(4.507); // '4.51'

sumAmounts(["1.00", "2.00", "4.00"]); // '7.00'
discountAmount("100.00", 2.5); // '97.50'
discountAmount("200.00", 4.28); // '191.44'

isAmountPositive("12.00"); // true
isAmountNegative("-12.00"); // true
isAmountZero("0.00"); // true
compareAmount("1.00", "3.00"); // -1

isValidAmount("0"); // false
isValidAmount("0.00"); // true

formatAmount("1234.00", "USD"); // 1,234.00

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Amount type

Also exported is the Amount TypeScript type.

import { Amount } from "money-fns";

const price: Amount = "50.00";

It represents a valid money value to be used by these functions.

An Amount is defined as a number with exactly 2 subdecimal digits. E.g. 123.45 or 1.00

These values are passed around as strings but you can import the Amount type and use in your code for more specificity.

Acknowledgments

money-fns was heavily inspired by money-math. money-fns hopes to bring it's concepts and modernise them with BigInts and out-of-the-box Typescript support.