# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [Unreleased]

### Added

- Multi-key `groupBy` via string/accessor arrays (e.g. `['country', 'status']`)
- `.toArray()` to export groups as `[{ key, items, …aggregates }]`
- `.count(alias)` and single-pass `.aggregate(spec)`
- `.reduce(alias, reducer, initial?)` for custom per-group folds
- `.orderBy(field, direction?)` to sort groups by key, alias, or function
- `.omitItems()` to drop raw `items` after aggregation (call last)
- Column accessors: string field or `(item) => value` for nested/derived values
- TypeScript declarations (`index.d.ts` / `index.d.mts`)
- ESM entry (`index.mjs`) with dual `package.json` `"exports"` for `import` and `require`
- Informal `npm run bench` benchmark script
- GitHub Actions CI on pull requests (Node 18 / 20 / 22)
- `groupBy(data, key, { strict: true })` to restore missing-key throws
- `aggregate()` accepts a list of entries per op (e.g. two `sum`s in one scan)

### Fixed

- `keys`, `firstGroup`, and `lastGroup` are live (reflect `.where()`)
- Empty groups are removed after `.where()`; aggregates guard empty `items`
- Safe `hasOwnProperty` for `Object.create(null)` rows
- `min` / `max` no longer risk stack overflow on large groups
- `distinctCount` is O(n) via `Set`
- Empty arrays return an empty result instead of throwing
- Missing grouping keys group under `"undefined"` instead of throwing (use `{ strict: true }` for the old behavior)
- `sum` / `avg` / `min` / `max` skip `null`, `undefined`, `''`, and non-finite values instead of producing `NaN`

### Changed

- README rewritten with real-world recipes (sales, logs, inventory) and an `Object.groupBy` comparison
- Publish workflow uses npm Trusted Publishing (OIDC) on Node 24; no `NPM_TOKEN`
- Fixtures directory renamed from `fixures` to `fixtures`

## [2.0.1] - 2024

### Fixed

- README and packaging tweaks after 2.0.0

## [2.0.0] - 2024

### Changed

- Breaking API refinements (see release commit history)

## [1.2.3] - 2022

### Fixed

- Patch release via automated version bump

## [1.2.0] - 2022

### Added

- Initial published aggregation helpers (`sum`, `avg`, `min`, `max`, `distinctCount`, `where`)

[Unreleased]: https://github.com/juli04guilar/groupBy/compare/v2.0.1...HEAD
[2.0.1]: https://github.com/juli04guilar/groupBy/compare/v2.0.0...v2.0.1
[2.0.0]: https://github.com/juli04guilar/groupBy/compare/v1.2.3...v2.0.0
[1.2.3]: https://github.com/juli04guilar/groupBy/compare/v1.2.0...v1.2.3
[1.2.0]: https://github.com/juli04guilar/groupBy/releases/tag/v1.2.0