Simple Decimal Money

A module to handle currency amounts as decimals. It relies on the toFixed method and rounds the values using toFixed(rounding) after every math operation. Decimal objects are immutable.

Works only for amounts with cents and nothing more. See examples below:

Installation

npm install simple-decimal-money

API

Create an object:

    import Decimal from 'simple-decimal-money';
    var dc1 = new Decimal(10.334); // numeric value
    var dc2 = new Decimal("10.334"); // string value
    var dc3 = new Decimal(dc2) // or another Decimal

Operations

Add:

    dc1.add(dc2); // returns new Decimal
    dc1.add(10.10) // add numeric value, returns new Decimal

Subtract:

    dc1.subtract(dc2);

Multiply:

    dc1.multiply(dc2);

DivideBy:

    dc1.divideBy(dc2);

Getting a number from Decimal:

    dc1.toNumber()

Getting a string from Decimal:

    dc1.toString() // always result of toFixed(2)

Additionally it's possible to specify another rounding precision:

    var dc1 = new Decimal(10.334, 3); // numeric value

It's handy for the tax rates because they can have more than 2 decimals.

Example of price with VAT calculation:

priceVAT: function() {
  var rate = new Decimal(this.get('tax.data.rate'), 3);
  var price = new Decimal(this.get('price'), 3);
  return price.multiply(rate.add(1)).toString();
}

The result will be rounded according to the caller object rounding property:

rate.add(1); // => rounding=3;
price.multiply(rate.add(1)) // => rounding = 3