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    0.6.3 • Public • Published

    JS Money

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    JS Money is a JavaScript implementation of Martin Fowlers Money pattern.


    The package is available through npm and bower.

    $ npm install js-money
    $ bower install js-money


    First we need to import the library.

    var Money = require('js-money');

    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, Money.EUR);
    var tenDollars = Money.fromInteger({ amount: 1000, currency: Money.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, Money.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, Money.EUR); // 5 EUR
    // add
    fiveEur.add(new Money(250, Money.EUR)); // 7.50 EUR
    // subtract 
    fiveEur.subtract(new Money(470, Money.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, Money.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, Money.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, Money.EUR);
    var anotherFiveEur = new Money(500, Money.EUR);
    var sevenEur = new Money(700, Money.EUR);
    var fiveDollars = new Money(500, Money.USD);
    fiveEur.equals(fiveDollars); // return false
    fiveEur.equals(anotherFiveEur); // return true
; // return -1; // return 1; // return 0
; // throw Error
    fiveEur.greaterThan(sevenEur); // return false
    fiveEur.greaterThanOrEqual(sevenEur); // return false
    fiveEur.lessThan(sevenEur); // return true
    fiveEur.lessThanOrEqual(fiveEur); // return true


    $ npm install
    $ npm test


    The MIT License

    Copyright (c) 2014 David Kalosi


    npm i js-money

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