# @joookiwi/collection

> A Javascript implementation of a collection based on Array (from Javascript/Java/Kotlin/C#/PHP), Set (from Javascript/Java/Kotlin) and List (from Java/Kotlin/C#)

Latest version **2.0.1** (published 2026-08-13) · MIT license · 0 weekly downloads

## Install

```sh
npm install @joookiwi/collection
pnpm add @joookiwi/collection
yarn add @joookiwi/collection
bun add @joookiwi/collection
```

## Health

**Score 70/100 (B)** — status: active.

Positive: has types; esm support; no vulnerabilities; recently updated; high maintenance score; high quality score.

Warnings: low downloads; large bundle.

## Facts

| | |
|---|---|
| Version | 2.0.1 |
| Published | 2026-08-13 |
| First published | 2023-07-02 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | ESM + CommonJS |
| Dependencies | 2 |
| Unpacked size | 18.2 MB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 2 |
| Author | JóôòKiwi |
| Maintainers | joookiwi |
| Keywords | immutable, iterable, iterator, collection, list, array, set, indices |

## Links

- npm: https://www.npmjs.com/package/@joookiwi/collection
- Repository: https://github.com/joooKiwi/collection
- Homepage: https://github.com/joooKiwi/collection#readme
- Issues: https://github.com/joooKiwi/collection/issues
- Funding: https://github.com/sponsors/joooKiwi
- npm.io page: https://npm.io/package/@joookiwi/collection

## Dependencies (2)

- [@joookiwi/lazy](https://npm.io/package/@joookiwi/lazy.md) ^1.7.3
- [@joookiwi/type](https://npm.io/package/@joookiwi/type.md) ^1.2.2

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## Recent versions

- 2.0.1 (latest) — 2026-08-13
- 2.0.0 — 2026-08-12
- 1.14.0 — 2026-02-24
- 1.13.0 — 2025-08-12
- 1.12.0 — 2025-01-09
- 1.11.3 — 2024-12-12
- 1.11.2 — 2024-11-19
- 1.11.1 — 2024-11-08
- 1.10.0 — 2024-10-08
- 1.9.3 — 2024-08-16
- 1.9.2 — 2024-07-23
- 1.9.1 — 2024-07-22
- 1.9.0 — 2024-07-21
- 1.8.0 — 2024-04-01
- 1.7.1 — 2024-02-19
- … 14 more at https://npm.io/package/@joookiwi/collection/versions

## README

# Collection (javascript version)
[![version][npm-image-link]][npm-link]
[![downloads][npm-download-image-link]][npm-download-link]

[npm-image-link]:          https://img.shields.io/npm/v/@joookiwi/collection.svg?logo=npm&label=
[npm-link]:                https://npmjs.org/package/@joookiwi/collection
[npm-download-image-link]: https://img.shields.io/npm/dt/@joookiwi/collection.svg
[npm-download-link]:       https://npm-stat.com/charts.html?package=@joookiwi/collection

## Table of content
* [Installation](#installation)
* [Usage](#usage)
  * [The size methods](#the-size-methods)
  * [The research methods](#the-research-methods)
  * [The index methods](#the-index-methods)
  * [The validation methods](#the-validation-methods)
  * [The transformation methods](#the-transformation-methods)
  * [The loop methods](#the-loop-methods)
  * [The reordering methods](#the-reordering-methods)
  * [The conversion methods](#the-conversion-methods)
  * [The utility methods](#the-utility-methods)
  * [Non-present methods](#non-present-methods)
* [Contribution](#contribution)

The way to think about this is to have the functionalities of other languages
(like `Java`, `PHP`, `C#`, `Kotlin` and even `Javascript`)
all in one standalone structure.

But, with a possible functional approach using the collections.

The structure is and will be in continuous change
to implement almost everything that the other languages have (if it is possible).

## Installation
```
npm install @joookiwi/collection
npm i @joookiwi/collection

npm install --save @joookiwi/collection
npm i -S @joookiwi/collection

npm install --save-dev @joookiwi/collection
npm i -D @joookiwi/collection
```

## Usage

There are 3 different kinds of collections (_which are all non-mutable_).
- a minimalist (`GenericMinimalistCollectionHolder`),
- a lazy (`LazyGenericCollectionHolder`)
- and an eager (`GenericCollectionHolder`) one.

So, no computation can be done _"normally"_ in these instances.

But they can always be converted to
the `Array`, `Set`,
`WeakSet` (it the type is a `WeakKey`)
or even `Map` depending on the usage.

It can be separated in different categories.
1. The **size** methods
2. The **research** methods
3. The **index** methods
4. The **validation** methods
5. The **transformation** methods
6. The **loop** methods
7. The **reordering** methods
8. The **conversion** methods
9. Some **utility** methods _(not part of the `CollectionHolder`)_

---
### The size methods

Those methods are associated with a size or directly compared
 - `size`|`length`|`count`
 - `isEmpty`
 - `isNotEmpty`

### The research methods

Those methods are meant to find an element comparing it
or giving a value from the **collection**
 - get value
   - `get`|`at`|`elementAt`
   - `getFirst`|`first`|`firstIndexed`
   - `getLast`|`last`|`lastIndexed`
 - get value or else
   - `getOrElse`|`atOrElse`|`elementAtOrElse`
 - get value or null
   - `getOrNull`|`atOrNull`|`elementAtOrNull`
   - `getFirstOrNull`|`firstOrNull`|`firstIndexedOrNull`
   - `getLastOrNull`|`lastOrNull`|`lastIndexedOrNull`
 - find first value
   - `findFirst`|`find`|`first`
   - `findFirstOrNull`|`findOrNull`|`firstOrNull`
   - `findFirstIndexed`|`findIndexed`|`firstIndexed`
   - `findFirstIndexedOrNull`|`findIndexedOrNull`|`firstIndexedOrNull`
 - find last value
   - `findLast`|`last`
   - `findLastOrNull`|`lastOrNull`
   - `findLastIndexed`|`lastIndexed`
   - `findLastIndexedOrNull`|`lastIndexedOrNull`

### The index methods

Those methods are giving or finding index values in the **collection**
 - get index
   - `firstIndexOf`|`indexOf`
   - `firstIndexOfOrNull`|`indexOfOrNull`
   - `lastIndexOf`
   - `lastIndexOfOrNull`
 - find first index
   - `indexOfFirst`|`findFirstIndex`|`findIndex`
   - `indexOfFirstOrNull`|`findFirstIndexOrNull`|`findIndexOrNull`
   - `indexOfFirstIndexed`|`findFirstIndexIndexed`|`findIndexIndexed`
   - `indexOfFirstIndexedOrNull`|`findFirstIndexIndexedOrNull`|`findIndexIndexedOrNull`
 - find last index
   - `indexOfLast`|`findLastIndex`
   - `indexOfLastOrNull`|`findLastIndexOrNull`
   - `indexOfLastIndexed`|`findLastIndexIndexed`
   - `indexOfLastIndexedOrNull`|`findLastIndexIndexedOrNull`

### The validation methods

Those methods are to give a validation on some type, value
or comparison across the **collection**
 -
   - `all`|`every`
   - `any`|`some`
   - `none`
 - has …
   - `hasNull`|`includesNull`|`containsNull`
   - `hasDuplicate`|`includesDuplicate`|`containsDuplicate`
   - `has`|`includes`|`contains`
   - `hasOne`|`includesOne`|`containsOne`
   - `hasAll`|`includesAll`|`containsAll`
 - `requireNotNull`

### The transformation methods

Those methods have the purpose to give a new **collection** 
with a possibly different type from the original **collection**
 - filter …
   - `filter`
   - `filterIndexed`
   - `filterNot`
   - `filterIndexedNot`
   - `filterNotNull`
 - slice …
   - `slice`
 - take …
   - `take`|`limit`
   - `takeWhile`|`limitWhile`
   - `takeWhileIndexed`|`limitWhileIndexed`
   - `takeLast`|`limitLast`
   - `takeLastWhile`|`limitLastWhile`
   - `takeLastWhileIndexed`|`limitLastWhileIndexed`
 - drop …
   - `drop`|`skip`
   - `dropWhile`|`skipWhile`
   - `dropWhileIndexed`|`skipWhileIndexed`
   - `dropLast`|`skipLast`
   - `dropLastWhile`|`skipLastWhile`
   - `dropLastWhileIndexed`|`skipLastWhileIndexed`
 - map …
   - `map`
   - `mapIndexed`
   - `mapNotNull`
   - `mapNotNullIndexed`

### The loop methods

Those methods are just doing a basic loop on the **collection**
 - `forEach`
 - `forEachIndexed`
 - `onEach`
 - `onEachIndexed`

### The reordering methods

Those methods are just changing the order to the elements of the **collection**
 - `toReverse`|`toReversed`|`reversed`

### The conversion methods

Those methods have the sole purpose to convert the structure from a **collection**
to another structure.
It can also convert the value to a **string**.
 - `toIterator`
 - `toArray`
 - `toMutableArray`
 - `toSet`
 - `toMutableSet`
 - `toWeakSet` (_only if the it is an `object`|`symbol` or in `GenericObjectCollectionHolder`_)
 - `toMutableWeakSet` (_only if it is an `object`|`symbol` or in `GenericObjectCollectionHolder`_)
 - `toMap`
 - `toMutableMap`
 - `toString`
 - `toLocaleString`
 - `toLowerCaseString`
 - `toLocaleLowerCaseString`
 - `toUpperCaseString`
 - `toLocaleUpperCaseString`
 - `joinToString`|`join`

### The utility methods

Those methods are not part of the `CollectionHolder`,
but are a complement to the overall robustest of the **collection**
 - as … string
   - `asString` (_This will be eventually moved in another project_)
   - `asLocaleString` (_This will be eventually moved in another project_)
   - `asLowerCaseString` (_This will be eventually moved in another project_)
   - `asLocaleLowerCaseString` (_This will be eventually moved in another project_)
   - `asUpperCaseString` (_This will be eventually moved in another project_)
   - `asLocaleUpperCaseString` (_This will be eventually moved in another project_)
 - is framework collection
   - `isCollectionHolder`
   - `isCollectionHolderByStructure`
   - `isMinimalistCollectionHolder`
   - `isMinimalistCollectionHoldeByStructure`
   - `isCollectionIterator`
   - `isCollectionIteratorByStructure`
 - is JavaScript collection
   - `isArray`
   - `isArrayByStructure`
   - `isTypedArray`
   - `isTypedArrayByStructure`
   - `isInt8Array`
   - `isInt8ArrayByStructure`
   - `isUint8Array`
   - `isUint8ArrayByStructure`
   - `isUint8ClampedArray`
   - `isUint8ClampedArrayByStructure`
   - `isInt16Array`
   - `isInt16ArrayByStructure`
   - `isUint16Array`
   - `isUint16ArrayByStructure`
   - `isInt32Array`
   - `isInt32ArrayByStructure`
   - `isUint32Array`
   - `isUint32ArrayByStructure`
   - `isBigInt64Array`
   - `isBigInt64ArrayByStructure`
   - `isBigUint64Array`
   - `isBigUint64ArrayByStructure`
   - `isFloat32Array`
   - `isFloat32ArrayByStructure`
   - `isFloat64Array`
   - `isFloat64ArrayByStructure`
   - `isSet`
   - `isSetByStructure`
   - `isIterator`

---

### Non-present methods

Almost every method is present in the `src/method` at the exception to
`get(index)` and `get size()` that is handled differently based on the type of instance.

The alias methods are not part of the extension function.
are `get length()` and `get count()`.

Eventually, those methods should be present.

## Contribution
You can contribute to great simple packages.
All with similar behaviour across different languages (like Java, Kotlin, C# and PHP).
It can be done 2 different ways:
 - [GitHub sponsor](https://github.com/sponsors/joooKiwi) or
 - [!["Buy me a Coffee"](https://img.buymeacoffee.com/button-api/?&button_colour=40DCA5&font_colour=ffffff&font_family=Cookie&outline_colour=000000&coffee_colour=FFDD00)](https://www.buymeacoffee.com/joookiwi)

---
_Source: https://npm.io/package/@joookiwi/collection · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._