# which-builtin-type > What is the type of this builtin JS value? Latest version **1.2.1** (published 2024-12-13) · MIT license · 0 weekly downloads ## Install ```sh npm install which-builtin-type pnpm add which-builtin-type yarn add which-builtin-type bun add which-builtin-type ``` ## Health **Score 50/100 (C)** — status: stable. Positive: has types; esm support; no vulnerabilities; high quality score. Warnings: low downloads. Negative: stale. ## Facts | | | |---|---| | Version | 1.2.1 | | Published | 2024-12-13 | | First published | 2020-01-25 | | Weekly downloads | 0 | | License | MIT | | TypeScript types | bundled | | Module format | ESM + CommonJS | | Node | >= 0.4 | | Dependencies | 13 | | Unpacked size | 29.3 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 3 | | Author | Jordan Harband | | Maintainers | ljharb | | Keywords | type, builtin, ecmascript | ## Links - npm: https://www.npmjs.com/package/which-builtin-type - Repository: https://github.com/inspect-js/which-builtin-type - Homepage: https://github.com/inspect-js/which-builtin-type#readme - Issues: https://github.com/inspect-js/which-builtin-type/issues - Funding: https://github.com/sponsors/ljharb - npm.io page: https://npm.io/package/which-builtin-type ## Dependencies (13) - [isarray](https://npm.io/package/isarray.md) ^2.0.5 - [is-regex](https://npm.io/package/is-regex.md) ^1.2.1 - [call-bound](https://npm.io/package/call-bound.md) ^1.0.2 - [is-weakref](https://npm.io/package/is-weakref.md) ^1.0.2 - [is-date-object](https://npm.io/package/is-date-object.md) ^1.1.0 - [has-tostringtag](https://npm.io/package/has-tostringtag.md) ^1.0.2 - [which-collection](https://npm.io/package/which-collection.md) ^1.0.2 - [is-async-function](https://npm.io/package/is-async-function.md) ^2.0.0 - [which-typed-array](https://npm.io/package/which-typed-array.md) ^1.1.16 - [is-generator-function](https://npm.io/package/is-generator-function.md) ^1.0.10 - [which-boxed-primitive](https://npm.io/package/which-boxed-primitive.md) ^1.1.0 - [function.prototype.name](https://npm.io/package/function.prototype.name.md) ^1.1.6 - [is-finalizationregistry](https://npm.io/package/is-finalizationregistry.md) ^1.1.0 ## Alternatives - [@openai/codex-sdk](https://npm.io/package/@openai/codex-sdk.md) — 731.4K weekly downloads - [babel-plugin-transform-react-jsx](https://npm.io/package/babel-plugin-transform-react-jsx.md) — 565.0K weekly downloads - [babel-helper-remove-or-void](https://npm.io/package/babel-helper-remove-or-void.md) — 508.5K weekly downloads - [@pnpm/store-controller-types](https://npm.io/package/@pnpm/store-controller-types.md) — 186.9K weekly downloads - [react-native-signature-canvas](https://npm.io/package/react-native-signature-canvas.md) — 155.6K weekly downloads ## Recent versions - 1.2.1 (latest) — 2024-12-13 - 1.2.0 — 2024-11-23 - 1.1.4 — 2024-07-29 - 1.1.3 — 2022-11-02 - 1.1.2 — 2022-04-12 - 1.1.1 — 2021-08-06 - 1.1.0 — 2021-04-18 - 1.0.1 — 2020-12-15 - 1.0.0 — 2020-01-25 ## README # which-builtin-type [![Version Badge][npm-version-svg]][package-url] [![github actions][actions-image]][actions-url] [![coverage][codecov-image]][codecov-url] [![License][license-image]][license-url] [![Downloads][downloads-image]][downloads-url] [![npm badge][npm-badge-png]][package-url] What is the type of this builtin JavaScript value? Works cross-realm, without `instanceof`, and can not be fooled by a `constructor` property. ## Example ```js var whichBuiltinType = require('which-builtin-type'); var assert = require('assert'); assert.equal(undefined, whichBuiltinType(undefined)); assert.equal(null, whichBuiltinType(null)); assert.equal('Boolean', whichBuiltinType(false)); assert.equal('Boolean', whichBuiltinType(true)); assert.equal('Array', whichBuiltinType([])); assert.equal('Object', whichBuiltinType({})); assert.equal('RegExp', whichBuiltinType(/a/g)); assert.equal('RegExp', whichBuiltinType(new RegExp('a', 'g'))); assert.equal('Date', whichBuiltinType(new Date())); assert.equal('Number', whichBuiltinType(42)); assert.equal('Number', whichBuiltinType(NaN)); assert.equal('Number', whichBuiltinType(Infinity)); assert.equal('Number', whichBuiltinType(new Number(42))); assert.equal('String', whichBuiltinType('foo')); assert.equal('String', whichBuiltinType(Object('foo'))); assert.equal('Function', whichBuiltinType(function () {})); assert.equal('GeneratorFunction', whichBuiltinType(function* () {})); assert.equal('Function', whichBuiltinType(x => x * x)); assert.equal('Array', whichBuiltinType([])); assert.equal('Int8Array', whichBuiltinType(new Int8Array())); assert.equal('Uint8Array', whichBuiltinType(new Uint8Array())); assert.equal('Uint8ClampedArray', whichBuiltinType(new Uint8ClampedArray())); assert.equal('Int16Array', whichBuiltinType(new Int16Array())); assert.equal('Uint16Array', whichBuiltinType(new Uint16Array())); assert.equal('Int32Array', whichBuiltinType(new Int32Array())); assert.equal('Uint32Array', whichBuiltinType(new Uint32Array())); assert.equal('Float32Array', whichBuiltinType(new Float32Array())); assert.equal('Float64Array', whichBuiltinType(new Float64Array())); assert.equal('BigInt64Array', whichBuiltinType(new BigInt64Array())); assert.equal('BigUint64Array', whichBuiltinType(new BigUint64Array())); ``` ## Tests Simply clone the repo, `npm install`, and run `npm test` [package-url]: https://npmjs.org/package/which-builtin-type [npm-version-svg]: https://versionbadg.es/inspect-js/which-builtin-type.svg [deps-svg]: https://david-dm.org/inspect-js/which-builtin-type.svg [deps-url]: https://david-dm.org/inspect-js/which-builtin-type [dev-deps-svg]: https://david-dm.org/inspect-js/which-builtin-type/dev-status.svg [dev-deps-url]: https://david-dm.org/inspect-js/which-builtin-type#info=devDependencies [npm-badge-png]: https://which-builtin-type/which-builtin-type.png?downloads=true&stars=true [license-image]: https://img.shields.io/npm/l/which-builtin-type.svg [license-url]: LICENSE [downloads-image]: https://img.shields.io/npm/dm/which-builtin-type.svg [downloads-url]: https://npm-stat.com/charts.html?package=which-builtin-type [codecov-image]: https://codecov.io/gh/inspect-js/which-builtin-type/branch/main/graphs/badge.svg [codecov-url]: https://app.codecov.io/gh/inspect-js/which-builtin-type/ [actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/inspect-js/which-builtin-type [actions-url]: https://github.com/inspect-js/which-builtin-type/actions --- _Source: https://npm.io/package/which-builtin-type · Machine-readable twin of the npm.io package page. 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