eslint-plugin-finlint

ESLint plugin for financial math accuracy — 13 rules that catch precision bugs in JavaScript and TypeScript.

Install

npm install eslint-plugin-finlint --save-dev

Usage (ESLint v9+ Flat Config)

// eslint.config.js
import finlint from 'eslint-plugin-finlint';

export default [finlint.configs.recommended];

Rules

| Rule | Default | Description | |------|---------|-------------| | finlint/no-float-money | warn | Financial variables should use Decimal, not number | | finlint/decimal-from-string | error | Decimal constructor should use string, not number literal | | finlint/money-parse | error | Don't use Number()/parseFloat() on money strings | | finlint/intl-number-format | warn | Use Intl.NumberFormat instead of toFixed() | | finlint/joint-ownership-sum-check | warn | Validate joint ownership percentages sum to 100% | | finlint/income-split-denominator-nonzero | error | Guard against zero income in split calculations | | finlint/income-basis-consistency | error | Don't mix gross/net income in splits | | finlint/aggregate-leaks-complement | error | Don't leak partner data via total - partner | | finlint/set-union-aggregation | error | Deduplicate shared accounts before aggregation | | finlint/no-math-round-money | warn | Don't use Math.round/floor/ceil on money | | finlint/intl-format-only | warn | Don't use string concat for money display | | finlint/negative-zero-check | warn | Use Object.is() to guard against -0 | | finlint/no-json-number-parse | error | Use a reviver with JSON.parse for financial data |

TypeScript

Works with @typescript-eslint/parser — FIN001 also detects number type annotations.

License

Apache-2.0 — github.com/kanso-finance/finlint