# which-boxed-primitive

> Which kind of boxed JS primitive is this?

Latest version **1.1.1** (published 2024-12-16) · MIT license · 0 weekly downloads

## Install

```sh
npm install which-boxed-primitive
pnpm add which-boxed-primitive
yarn add which-boxed-primitive
bun add which-boxed-primitive
```

## Health

**Score 45/100 (D)** — status: stable.

Positive: has types; no vulnerabilities; high quality score.

Warnings: low downloads; no esm support.

Negative: stale.

## Facts

| | |
|---|---|
| Version | 1.1.1 |
| Published | 2024-12-16 |
| First published | 2019-08-10 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | CommonJS |
| Node | >= 0.4 |
| Dependencies | 5 |
| Unpacked size | 18.8 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 7 |
| Author | Jordan Harband |
| Maintainers | ljharb |
| Keywords | boxed, primitive, object, ecmascript, javascript, which |

## Links

- npm: https://www.npmjs.com/package/which-boxed-primitive
- Repository: https://github.com/inspect-js/which-boxed-primitive
- Homepage: https://github.com/inspect-js/which-boxed-primitive#readme
- Issues: https://github.com/inspect-js/which-boxed-primitive/issues
- Funding: https://github.com/sponsors/ljharb
- npm.io page: https://npm.io/package/which-boxed-primitive

## Dependencies (5)

- [is-bigint](https://npm.io/package/is-bigint.md) ^1.1.0
- [is-string](https://npm.io/package/is-string.md) ^1.1.1
- [is-symbol](https://npm.io/package/is-symbol.md) ^1.1.1
- [is-number-object](https://npm.io/package/is-number-object.md) ^1.1.1
- [is-boolean-object](https://npm.io/package/is-boolean-object.md) ^1.2.1

## Recent versions

- 1.1.1 (latest) — 2024-12-16
- 1.1.0 — 2024-12-02
- 1.0.2 — 2020-12-14
- 1.0.1 — 2019-08-11
- 1.0.0 — 2019-08-10

## README

# which-boxed-primitive <sup>[![Version Badge][2]][1]</sup>

[![dependency status][5]][6]
[![dev dependency status][7]][8]
[![License][license-image]][license-url]
[![Downloads][downloads-image]][downloads-url]

[![npm badge][11]][1]

Which kind of boxed JS primitive is this? This module works cross-realm/iframe, does not depend on `instanceof` or mutable properties, and works despite ES6 Symbol.toStringTag.

## Example

```js
var whichBoxedPrimitive = require('which-boxed-primitive');
var assert = require('assert');

// unboxed primitives return `null`
// boxed primitives return the builtin constructor name

assert.equal(whichBoxedPrimitive(undefined), null);
assert.equal(whichBoxedPrimitive(null), null);

assert.equal(whichBoxedPrimitive(false), null);
assert.equal(whichBoxedPrimitive(true), null);
assert.equal(whichBoxedPrimitive(new Boolean(false)), 'Boolean');
assert.equal(whichBoxedPrimitive(new Boolean(true)), 'Boolean');

assert.equal(whichBoxedPrimitive(42), null);
assert.equal(whichBoxedPrimitive(NaN), null);
assert.equal(whichBoxedPrimitive(Infinity), null);
assert.equal(whichBoxedPrimitive(new Number(42)), 'Number');
assert.equal(whichBoxedPrimitive(new Number(NaN)), 'Number');
assert.equal(whichBoxedPrimitive(new Number(Infinity)), 'Number');

assert.equal(whichBoxedPrimitive(''), null);
assert.equal(whichBoxedPrimitive('foo'), null);
assert.equal(whichBoxedPrimitive(new String('')), 'String');
assert.equal(whichBoxedPrimitive(new String('foo')), 'String');

assert.equal(whichBoxedPrimitive(Symbol()), null);
assert.equal(whichBoxedPrimitive(Object(Symbol()), 'Symbol');

assert.equal(whichBoxedPrimitive(42n), null);
assert.equal(whichBoxedPrimitive(Object(42n), 'BigInt');

// non-boxed-primitive objects return `undefined`
assert.equal(whichBoxedPrimitive([]), undefined);
assert.equal(whichBoxedPrimitive({}), undefined);
assert.equal(whichBoxedPrimitive(/a/g), undefined);
assert.equal(whichBoxedPrimitive(new RegExp('a', 'g')), undefined);
assert.equal(whichBoxedPrimitive(new Date()), undefined);
assert.equal(whichBoxedPrimitive(function () {}), undefined);
assert.equal(whichBoxedPrimitive(function* () {}), undefined);
assert.equal(whichBoxedPrimitive(x => x * x), undefined);
assert.equal(whichBoxedPrimitive([]), undefined);

```

## Tests
Simply clone the repo, `npm install`, and run `npm test`

[1]: https://npmjs.org/package/which-boxed-primitive
[2]: https://versionbadg.es/inspect-js/which-boxed-primitive.svg
[5]: https://david-dm.org/inspect-js/which-boxed-primitive.svg
[6]: https://david-dm.org/inspect-js/which-boxed-primitive
[7]: https://david-dm.org/inspect-js/which-boxed-primitive/dev-status.svg
[8]: https://david-dm.org/inspect-js/which-boxed-primitive#info=devDependencies
[11]: https://nodei.co/npm/which-boxed-primitive.png?downloads=true&stars=true
[license-image]: https://img.shields.io/npm/l/which-boxed-primitive.svg
[license-url]: LICENSE
[downloads-image]: https://img.shields.io/npm/dm/which-boxed-primitive.svg
[downloads-url]: https://npm-stat.com/charts.html?package=which-boxed-primitive

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