USA Bank Working Day

Toolkit for checking whether a given calendar date is a U.S. federal bank holiday (weekends included) and for computing related working-day helpers.

• Input date format: "yyyy-mm-dd" or "yyyy-m-d"
• Holiday source: https://www.federalreserve.gov/aboutthefed/k8.htm

Install

# Bun (preferred)
bun add usa-bank-working-day

# npm
npm i usa-bank-working-day

Usage

All APIs accept either a Date or a date string. When a method returns a date, it returns a Date object (constructed at local noon to avoid DST/midnight edge cases).

import toolkit, {
  UsaBankWorkingDayToolKit,
  createUsaBankWorkingDayToolKit,
} from "usa-bank-working-day";

const toYMD = (d: Date) => `${d.getFullYear()}-${d.getMonth() + 1}-${d.getDate()}`;

toolkit.isBankHoliday("2020-7-3"); // true

toYMD(toolkit.getLastWorkingDate("2018-1-2")); // "2017-12-29"

toYMD(toolkit.fixedDateHolidayAdjust("2020-7-4")); // "2020-7-3" (observed)

// Prefer a fresh instance if you want isolated configuration/cache:
const isolated = createUsaBankWorkingDayToolKit();
const alsoIsolated = new UsaBankWorkingDayToolKit();

CommonJS

const toolkit = require("usa-bank-working-day");

toolkit.isBankHoliday("2022-01-17");

// Named exports are attached onto the default export for CJS:
const { UsaBankWorkingDayToolKit, createUsaBankWorkingDayToolKit } = toolkit;

API Notes

• isBankHoliday(date) returns true for weekends (Sat/Sun) and observed federal holidays.
• fixedDateHolidayAdjust(date) applies observation rules: Sunday -> Monday, Saturday -> Friday.
• getDateOfOrdinalHoliday(date, holiday) / getDateOfFixedDateHoliday(date, holiday) use a "target year" from the first argument.
• Months are 0-indexed (0 = January, 11 = December).
• Historical applicability is modeled for holidays where it matters (e.g., Juneteenth is effective starting in 2021).
• Special case: Dec 31 on a Friday is treated as a bank holiday (New Year's observed).

Development

# Install deps
bun install

# Run all tests
bun test

# Coverage
bun test --coverage

# Run a single test by name
bun test -t "isBankHoliday"

# Run a single test file
bun test test/main.test.ts

# Build (tsup -> dist/cjs + dist/esm)
bun run build

# Package + compatibility gates (npm pack + publint + arethetypeswrong + runtime smokes)
bun run check:package

Package / Exports Behavior

This package publishes both ESM and CJS via exports:

• require("usa-bank-working-day") resolves to dist/cjs/index.cjs
• import ... from "usa-bank-working-day" resolves to dist/esm/index.mjs

dist/cjs/index.cjs and dist/esm/index.mjs are small wrappers that:

• preserve the historical default export shape (the default singleton toolkit instance)
• expose modern named exports (UsaBankWorkingDayToolKit, createUsaBankWorkingDayToolKit) in both module systems

In CJS, those named exports are attached as properties on the default export; in ESM they are real named exports.

Migration Notes (Jest/Rollup -> Bun/tsup)

• Tests: yarn test / npx jest ... -> bun test (and bun test -t "name")
• Build: yarn rollup -> bun run build (tsup)
• Packaging verification: use bun run check:package (runs npm pack, publint, and @arethetypeswrong/cli plus runtime smokes)

License

ISC