@thi.ng/sparse-set
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TypedArray-based sparse set implementations with extended ES Set API
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# 
[](https://www.npmjs.com/package/@thi.ng/sparse-set)
[](https://mastodon.thi.ng/@toxi)
> [!NOTE]
> This is one of 209 standalone projects, maintained as part
> of the [.ng/umbrella](https://github.com/thi-ng/umbrella/) monorepo
> and anti-framework.
>
> 🚀 Please help me to work full-time on these projects by [sponsoring me on
> GitHub](https://github.com/sponsors/postspectacular). Thank you! ❤️
- [About](#about)
- [SparseSet8/16/32](#sparseset81632)
- [Status](#status)
- [Related packages](#related-packages)
- [Installation](#installation)
- [Dependencies](#dependencies)
- [API](#api)
- [Authors](#authors)
- [License](#license)
## About
TypedArray-based sparse set implementations with extended ES Set API.
This package contains functionality which was previously part of and has been
extracted from the [.ng/associative](https://thi.ng/associative) package.
### SparseSet8/16/32
[Sparse sets](https://research.swtch.com/sparse) provide super fast
(approx. 4x faster than the native `Set` impl) insertion & lookups for
numeric values in the interval `[0..n)` . The implementation in this
package provides most of the ES6 Set API and internally relies on 2 uint
typed arrays, with the actual backing type dependent on `n`.
Furthermore, unless (or until) values are being removed from the set,
they retain their original insertion order. For some use cases (e.g.
deduplication of values), this property can be very useful.
```ts
import { defSparseSet } from "@thi.ng/sparse-set";
// create sparse set for value range 0 - 99 (uint8 backed)
const a = defSparseSet(100);
a.into([99, 42, 66, 23, 66, 42]);
// SparseSet8 { 99, 42, 66, 23 }
a.has(66)
// true
// sparse sets are iterable
[...a]
// [ 99, 42, 66, 23 ]
// attempting to add out-of-range values will fail
a.add(100)
// SparseSet8 { 99, 42, 66, 23 }
// create sparse set for 16 bit value range 0 - 0xffff (uint16 backed)
const b = defSparseSet(0x10000);
// SparseSet16 {}
```
## Status
**STABLE** - used in production
[Search or submit any issues for this package](https://github.com/thi-ng/umbrella/issues?q=%5Bsparse-set%5D+in%3Atitle)
## Related packages
- [.ng/associative](https://github.com/thi-ng/umbrella/tree/develop/packages/associative) - ES Map/Set-compatible implementations with customizable equality semantics & supporting operations
## Installation
```bash
yarn add .ng/sparse-set
```
ESM import:
```ts
import * as ss from "@thi.ng/sparse-set";
```
Browser ESM import:
```html
<script type="module" src="https://esm.run/@thi.ng/sparse-set"></script>
```
[JSDelivr documentation](https://www.jsdelivr.com/)
For Node.js REPL:
```js
const ss = await import("@thi.ng/sparse-set");
```
Package sizes (brotli'd, pre-treeshake): ESM: 1.12 KB
## Dependencies
- [.ng/api](https://github.com/thi-ng/umbrella/tree/develop/packages/api)
- [.ng/associative](https://github.com/thi-ng/umbrella/tree/develop/packages/associative)
- [.ng/checks](https://github.com/thi-ng/umbrella/tree/develop/packages/checks)
- [.ng/errors](https://github.com/thi-ng/umbrella/tree/develop/packages/errors)
Note: .ng/api is in _most_ cases a type-only import (not used at runtime)
## API
[Generated API docs](https://docs.thi.ng/umbrella/sparse-set/)
TODO
## Authors
- [Karsten Schmidt](https://thi.ng)
If this project contributes to an academic publication, please cite it as:
```bibtex
{thing-sparse-set,
title = "@thi.ng/sparse-set",
author = "Karsten Schmidt",
note = "https://thi.ng/sparse-set",
year = 2019
}
```
## License
© 2019 - 2025 Karsten Schmidt // Apache License 2.0