TS Money

TS Money is a Typescript port of the great js-money package, which is an implementation of Martin Fowlers Money pattern.

Install

$ npm install ts-money

Usage

First we need to import the library.

import { Money, Currencies } from 'ts-money'

or in javascript:

var TsMoney = require('ts-money')
var Money = TsMoney.Money
var Currencies = TsMoney.Currencies

Creating a new instance

There are multiple options of what to pass into the constructor to create a new Money instance:

• amount as number, currency as string
• amount as number, currency as object
• object with amount and currency fields (only with fromInteger and fromDecimal methods)

Amounts can be supplied either as integers or decimal numbers.

Instances of Money are immutable and each arithmetic operation will return a new instance of the object.

When using decimals the library will allow only decimals with the precision allowed by the currencies smallest unit.

var fiveEur = new Money(500, Currencies.EUR);
var tenDollars = Money.fromInteger({ amount: 1000, currency: Currencies.USD });
var someDollars = Money.fromDecimal(15.25, 'USD');

// the following will fail and throw an Error since USD allows for 2 decimals
var moreDollars = Money.fromDecimal(15.3456, Currencies.USD);
// but with rounder function provider the following will work
var someMoreDollars = Money.fromDecimal(15.12345, 'USD', Math.ceil);

The currency object hold the following properties

    {
        "symbol": "$",
        "name": "US Dollar",
        "symbol_native": "$",
        "decimal_digits": 2,
        "rounding": 0,
        "code": "USD",
        "name_plural": "US dollars"
    }

Basic arithmetics

Arithmetic operations involving multiple objects are only possible on instances with the same currency and will throw an Error otherwise.

var fiveEur = new Money(500, Currencies.EUR); // 5 EUR

// add
fiveEur.add(new Money(250, Currencies.EUR)); // 7.50 EUR

// subtract 
fiveEur.subtract(new Money(470, Currencies.EUR)); // 0.30 EUR

// multiply
fiveEur.multiply(1.2345); // 6.17 EUR
fiveEur.multiply(1.2345, Math.ceil); // 6.18 EUR

// divide 
fiveEur.divide(2.3456); // 2.13 EUR
fiveEur.divide(2.3456, Math.ceil); // 2.14 EUR

Allocating funds

Will divide the funds based on the ratio without loosing any pennies.

var tenEur = new Money(1000, Currencies.EUR);

// divide 10 EUR into 3 parts
var shares = tenEur.allocate([1,1,1]); 
// returns an array of Money instances worth [334,333,333]

// split 5 EUR 70/30
var fiveEur = new Money(500, Currencies.EUR);
var shares = fiveEur.allocate([70,30]);
// returns an array of money [350,150]

Comparison and equality

Two objects are equal when they are of the same amount and currency. Trying to compare 2 objects with different currencies will throw an Error.

var fiveEur = new Money(500, Currencies.EUR);
var anotherFiveEur = new Money(500, Currencies.EUR);
var sevenEur = new Money(700, Currencies.EUR);
var fiveDollars = new Money(500, Currencies.USD);

fiveEur.equals(fiveDollars); // return false
fiveEur.equals(anotherFiveEur); // return true

fiveEur.compare(sevenEur); // return -1
sevenEur.compare(fiveEur); // return 1
fiveEur.compare(anotherFiveEur); // return 0

fiveEur.compare(fileDollars); // throw Error

fiveEur.greaterThan(sevenEur); // return false
fiveEur.greaterThanOrEqual(sevenEur); // return false
fiveEur.lessThan(sevenEur); // return true
fiveEur.lessThanOrEqual(fiveEur); // return true

Modifications

Some changes have been made compared with the javascript version:

Currencies object

Currencies are now in a stand-alone object. This has many benefits, like preventing autocomplete "pollution" of the Money class and enabling easy extensibility:

import { Money, Currencies } from 'ts-money'

Currencies.LTC = {
    symbol: "Ł",
    name: "Litecoin",
    symbol_native: "Ł",
    decimal_digits: 8,
    rounding: 0,
    code: "LTC",
    name_plural: "Litecoins"    
}

let m1 = new Money(12, 'LTC')
let m2 = new Money(234, Currencies.USD)
let m3 = new Money(543, Currencies.LTC)

Case insensitive currencies

Money accepts currencies as case insensitive:

let m1 = new Money(1, 'usd')
let m2 = new Money(2, 'USD')
let m3 = new Money(3, 'Usd')

Tests

$ npm install
$ npm test

License

The MIT License