DDecimal

Fixed-point decimal for TypeScript and Go. No floats, no surprises.

d("0.1").add(d("0.2")).toString(); // "0.30", not 0.30000000000000004

Numbers are stored as integers scaled by 100, two decimal places, deterministic rounding, works the same everywhere.

Install

npm install ddecimal

TypeScript

import { Decimal, d } from "ddecimal";

const a = d("19.99");
const b = d("5.50");
a.add(b).toString(); // "25.49"

const total = Decimal.sum(["19.99", "5.50", "129.00"].map(d));
total.mul(d("0.10")).toString(); // "15.45"

Node >= 18. Works with both import and require.

const { Decimal, d } = require("ddecimal");

API

| | | | ------------------------------------------- | --------------------- | | Decimal.zero() | 0.00 | | Decimal.fromInt(n) | 5n → "5.00" | | Decimal.fromNumber(n) | rounds to 2 decimals | | Decimal.fromRaw(n) | 199n → "1.99" | | Decimal.parse(s) | "1.5" → "1.50" | | d(s) | shorthand for parse | | .add() / .sub() | + / - | | .mul() / .div() | × / ÷ with rounding | | .neg() / .abs() | sign | | .eq() .gt() .gte() .lt() .lte() | comparisons | | .cmp() | -1 / 0 / 1 | | .isZero() .isPositive() .isNegative() | check sign | | .toString() | "12.34" | | .toNumber() | lossy | | .toBigInt() | truncates | | .toJSON() | "12.34" | | Decimal.sum(arr) | total | | .clamp(min, max) | clamp | | Decimal.max() Decimal.min() | min / max |

Go

import "github.com/tyowk/decimal/go"

a := decimal.MustParse("19.99")
b := decimal.MustParse("5.50")
total := a.Add(b)
fmt.Println(total) // "25.49"

Why not float?

Floating-point can't represent decimals like 0.1 exactly. For money, tax, or anywhere rounding matters, you need fixed-point. This library uses bigint (TS) / int64 (Go) under the hood. fast, predictable, no hidden error.

License

MIT