@zxteam/financial NPM

ZXTeam's Financial

Financial is a data type for storing decimal values and manipulate its via mathematical functions according infinite-precision arithmetic. It should be used when it is important to preserve exact precision, for example with monetary data.

Problems of JavaScript IEEE 754 floating point numbers.

Approximation

const totalMoney = 600.9;
const pricePerItem = 200.3;
const totalSpent = pricePerItem * 3;

console.log(totalMoney === totalSpent); // false (while expected true)
console.log(totalSpent); // 600.9000000000001

Digits limit

const left = parseInt("123456789012345678901234567890");
const right = parseInt("1");
const result = left + right;
console.log(result); // 1.2345678901234568e+29 (while expected 123456789012345678901234567891)

Examples

You can see a lot of examples in unit tests. Here we show some points only.

Avoid approximation

const { financial } = require("@zxteam/financial");

const totalMoney = financial.fromFloat(600.90, 2);
const pricePerItem = financial.fromFloat(200.30, 2);
const buyItems = financial.fromInt(3);
const totalSpent = financial.multiply(pricePerItem, buyItems);

console.log(financial.equalsTo(totalMoney, totalSpent)); // true
console.log(financial.toString(totalSpent));             // 600.9

Avoid digits limit

import { financial } from "@zxteam/financial";

const left = "123456789012345678901234567890";
const right = "1";
const result = financial.plus(left, right);
console.log(result); // 123456789012345678901234567891