| 1 | # which-builtin-type <sup>[![Version Badge][npm-version-svg]][package-url]</sup>
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| 2 |
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| 3 | [![github actions][actions-image]][actions-url]
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| 4 | [![coverage][codecov-image]][codecov-url]
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| 5 | [![License][license-image]][license-url]
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| 6 | [![Downloads][downloads-image]][downloads-url]
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| 7 |
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| 8 | [![npm badge][npm-badge-png]][package-url]
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| 9 |
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| 10 | What is the type of this builtin JavaScript value? Works cross-realm, without `instanceof`, and can not be fooled by a `constructor` property.
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| 11 |
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| 12 | ## Example
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| 13 |
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| 14 | ```js
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| 15 | var whichBuiltinType = require('which-builtin-type');
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| 16 | var assert = require('assert');
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| 17 |
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| 18 | assert.equal(undefined, whichBuiltinType(undefined));
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| 19 | assert.equal(null, whichBuiltinType(null));
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| 20 | assert.equal('Boolean', whichBuiltinType(false));
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| 21 | assert.equal('Boolean', whichBuiltinType(true));
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| 22 | assert.equal('Array', whichBuiltinType([]));
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| 23 | assert.equal('Object', whichBuiltinType({}));
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| 24 | assert.equal('RegExp', whichBuiltinType(/a/g));
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| 25 | assert.equal('RegExp', whichBuiltinType(new RegExp('a', 'g')));
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| 26 | assert.equal('Date', whichBuiltinType(new Date()));
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| 27 | assert.equal('Number', whichBuiltinType(42));
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| 28 | assert.equal('Number', whichBuiltinType(NaN));
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| 29 | assert.equal('Number', whichBuiltinType(Infinity));
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| 30 | assert.equal('Number', whichBuiltinType(new Number(42)));
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| 31 | assert.equal('String', whichBuiltinType('foo'));
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| 32 | assert.equal('String', whichBuiltinType(Object('foo')));
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| 33 | assert.equal('Function', whichBuiltinType(function () {}));
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| 34 | assert.equal('GeneratorFunction', whichBuiltinType(function* () {}));
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| 35 | assert.equal('Function', whichBuiltinType(x => x * x));
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| 36 | assert.equal('Array', whichBuiltinType([]));
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| 37 | assert.equal('Int8Array', whichBuiltinType(new Int8Array()));
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| 38 | assert.equal('Uint8Array', whichBuiltinType(new Uint8Array()));
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| 39 | assert.equal('Uint8ClampedArray', whichBuiltinType(new Uint8ClampedArray()));
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| 40 | assert.equal('Int16Array', whichBuiltinType(new Int16Array()));
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| 41 | assert.equal('Uint16Array', whichBuiltinType(new Uint16Array()));
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| 42 | assert.equal('Int32Array', whichBuiltinType(new Int32Array()));
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| 43 | assert.equal('Uint32Array', whichBuiltinType(new Uint32Array()));
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| 44 | assert.equal('Float32Array', whichBuiltinType(new Float32Array()));
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| 45 | assert.equal('Float64Array', whichBuiltinType(new Float64Array()));
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| 46 | assert.equal('BigInt64Array', whichBuiltinType(new BigInt64Array()));
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| 47 | assert.equal('BigUint64Array', whichBuiltinType(new BigUint64Array()));
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| 48 | ```
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| 49 |
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| 50 | ## Tests
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| 51 | Simply clone the repo, `npm install`, and run `npm test`
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| 52 |
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| 53 | [package-url]: https://npmjs.org/package/which-builtin-type
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| 54 | [npm-version-svg]: https://versionbadg.es/inspect-js/which-builtin-type.svg
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| 55 | [deps-svg]: https://david-dm.org/inspect-js/which-builtin-type.svg
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| 56 | [deps-url]: https://david-dm.org/inspect-js/which-builtin-type
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| 57 | [dev-deps-svg]: https://david-dm.org/inspect-js/which-builtin-type/dev-status.svg
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| 58 | [dev-deps-url]: https://david-dm.org/inspect-js/which-builtin-type#info=devDependencies
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| 59 | [npm-badge-png]: https://which-builtin-type/which-builtin-type.png?downloads=true&stars=true
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| 60 | [license-image]: https://img.shields.io/npm/l/which-builtin-type.svg
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| 61 | [license-url]: LICENSE
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| 62 | [downloads-image]: https://img.shields.io/npm/dm/which-builtin-type.svg
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| 63 | [downloads-url]: https://npm-stat.com/charts.html?package=which-builtin-type
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| 64 | [codecov-image]: https://codecov.io/gh/inspect-js/which-builtin-type/branch/main/graphs/badge.svg
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| 65 | [codecov-url]: https://app.codecov.io/gh/inspect-js/which-builtin-type/
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| 66 | [actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/inspect-js/which-builtin-type
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| 67 | [actions-url]: https://github.com/inspect-js/which-builtin-type/actions
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