{"id":15003596,"url":"https://github.com/stdlib-js/utils-constructor-name","last_synced_at":"2025-10-30T11:30:32.082Z","repository":{"id":41358038,"uuid":"376623873","full_name":"stdlib-js/utils-constructor-name","owner":"stdlib-js","description":"Determine the name of a value's constructor.","archived":false,"fork":false,"pushed_at":"2025-01-20T02:12:05.000Z","size":593,"stargazers_count":2,"open_issues_count":0,"forks_count":0,"subscribers_count":3,"default_branch":"main","last_synced_at":"2025-02-02T08:02:53.505Z","etag":null,"topics":["check","class","constructor","ctor","instanceof","is","istype","javascript","name","node","node-js","nodejs","stdlib","type","typeof","util","utilities","utility","utils"],"latest_commit_sha":null,"homepage":"https://github.com/stdlib-js/stdlib","language":"JavaScript","has_issues":false,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"apache-2.0","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/stdlib-js.png","metadata":{"files":{"readme":"README.md","changelog":"CHANGELOG.md","contributing":"CONTRIBUTING.md","funding":null,"license":"LICENSE","code_of_conduct":"CODE_OF_CONDUCT.md","threat_model":null,"audit":null,"citation":"CITATION.cff","codeowners":null,"security":"SECURITY.md","support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null},"funding":{"github":["stdlib-js"],"open_collective":"stdlib","tidelift":"npm/@stdlib/stdlib"}},"created_at":"2021-06-13T19:24:17.000Z","updated_at":"2025-01-20T01:49:57.000Z","dependencies_parsed_at":"2023-10-05T08:12:19.118Z","dependency_job_id":"637d5e68-af49-4665-b9fe-4496b143af3b","html_url":"https://github.com/stdlib-js/utils-constructor-name","commit_stats":{"total_commits":53,"total_committers":2,"mean_commits":26.5,"dds":"0.018867924528301883","last_synced_commit":"cf554d42372b1e0fe3bf1a55b8a2622d53f7cb1d"},"previous_names":[],"tags_count":28,"template":false,"template_full_name":null,"repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/stdlib-js%2Futils-constructor-name","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/stdlib-js%2Futils-constructor-name/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/stdlib-js%2Futils-constructor-name/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/stdlib-js%2Futils-constructor-name/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/stdlib-js","download_url":"https://codeload.github.com/stdlib-js/utils-constructor-name/tar.gz/refs/heads/main","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":238955774,"owners_count":19558454,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["check","class","constructor","ctor","instanceof","is","istype","javascript","name","node","node-js","nodejs","stdlib","type","typeof","util","utilities","utility","utils"],"created_at":"2024-09-24T18:59:10.511Z","updated_at":"2025-10-30T11:30:32.075Z","avatar_url":"https://github.com/stdlib-js.png","language":"JavaScript","readme":"\u003c!--\n\n@license Apache-2.0\n\nCopyright (c) 2018 The Stdlib Authors.\n\nLicensed under the Apache License, Version 2.0 (the \"License\");\nyou may not use this file except in compliance with the License.\nYou may obtain a copy of the License at\n\n   http://www.apache.org/licenses/LICENSE-2.0\n\nUnless required by applicable law or agreed to in writing, software\ndistributed under the License is distributed on an \"AS IS\" BASIS,\nWITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\nSee the License for the specific language governing permissions and\nlimitations under the License.\n\n--\u003e\n\n\n\u003cdetails\u003e\n  \u003csummary\u003e\n    About stdlib...\n  \u003c/summary\u003e\n  \u003cp\u003eWe believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.\u003c/p\u003e\n  \u003cp\u003eThe library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.\u003c/p\u003e\n  \u003cp\u003eWhen you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.\u003c/p\u003e\n  \u003cp\u003eTo join us in bringing numerical computing to the web, get started by checking us out on \u003ca href=\"https://github.com/stdlib-js/stdlib\"\u003eGitHub\u003c/a\u003e, and please consider \u003ca href=\"https://opencollective.com/stdlib\"\u003efinancially supporting stdlib\u003c/a\u003e. We greatly appreciate your continued support!\u003c/p\u003e\n\u003c/details\u003e\n\n# Constructor Name\n\n[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] \u003c!-- [![dependencies][dependencies-image]][dependencies-url] --\u003e\n\n\u003e Determine the name of a value's constructor.\n\n\u003csection class=\"installation\"\u003e\n\n## Installation\n\n```bash\nnpm install @stdlib/utils-constructor-name\n```\n\nAlternatively,\n\n-   To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).\n-   If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).\n-   For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).\n\nThe [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.\n\nTo view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.\n\n\u003c/section\u003e\n\n\u003csection class=\"usage\"\u003e\n\n## Usage\n\n```javascript\nvar constructorName = require( '@stdlib/utils-constructor-name' );\n```\n\n#### constructorName( value )\n\nReturns the name of a value's constructor.\n\n```javascript\nvar v = constructorName( 'a' );\n// returns 'String'\n\nv = constructorName( 5 );\n// returns 'Number'\n\nfunction Beep() {\n    return this;\n}\nv = constructorName( new Beep() );\n// returns 'Beep'\n```\n\n| description           | value                               | constructor           | notes        |\n| --------------------- | ----------------------------------- | --------------------- | ------------ |\n| string                | `'beep'`                            | `'String'`            |              |\n| number                | `5`                                 | `'Number'`            |              |\n| NaN                   | `NaN`                               | `'Number'`            |              |\n| infinity              | `+infinity`/`-infinity`             | `'Number'`            |              |\n| boolean               | `true`/`false`                      | `'Boolean'`           |              |\n| null                  | `null`                              | `'Null'`              |              |\n| undefined             | `undefined`                         | `'Undefined'`         |              |\n| array                 | `['beep', 5]`                       | `'Array'`             |              |\n| object                | `{'foo': 'bar'}`                    | `'Object'`            |              |\n| function              | `function (){}`                     | `'Function'`          |              |\n| symbol                | `Symbol()`                          | `'Symbol'`            | ES2015       |\n| regexp                | `/./`                               | `'RegExp'`            | Android 4.1+ |\n| String                | `new String('beep')`                | `'String'`            |              |\n| Number                | `new Number(5)`                     | `'Number'`            |              |\n| Boolean               | `new Boolean(false)`                | `'Boolean'`           |              |\n| Object                | `new Object()`                      | `'Object'`            |              |\n| Array                 | `new Array()`                       | `'Array'`             |              |\n| Int8Array             | `new Int8Array()`                   | `'Int8Array'`         |              |\n| Uint8Array            | `new Uint8Array()`                  | `'Uint8Array'`        |              |\n| Uint8ClampedArray     | `new Uint8ClampedArray()`           | `'Uint8ClampedArray'` |              |\n| Int16Array            | `new Int16Array()`                  | `'Int16Array'`        |              |\n| Uint16Array           | `new Uint16Array()`                 | `'Uint16Array'`       |              |\n| Int32Array            | `new Int32Array()`                  | `'Int32Array'`        |              |\n| Uint32Array           | `new Uint32Array()`                 | `'Uint32Array'`       |              |\n| Float32Array          | `new Float32Array()`                | `'Float32Array'`      |              |\n| Float64Array          | `new Float64Array()`                | `'Float64Array'`      |              |\n| ArrayBuffer           | `new ArrayBuffer()`                 | `'ArrayBuffer'`       |              |\n| Buffer                | `new Buffer()`                      | `'Buffer'`            | Node.js      |\n| Date                  | `new Date()`                        | `'Date'`              |              |\n| RegExp                | `new RegExp('.')`                   | `'RegExp'`            | Android 4.1+ |\n| Function              | `new Function('x', 'return x')`     | `'Function'`          |              |\n| Map                   | `new Map()`                         | `'Map'`               | ES2015       |\n| WeakMap               | `new WeakMap()`                     | `'WeakMap'`           | ES2015       |\n| Set                   | `new Set()`                         | `'Set'`               | ES2015       |\n| WeakSet               | `new WeakSet()`                     | `'WeakSet'`           | ES2015       |\n| Error                 | `new Error()`                       | `'Error'`             |              |\n| TypeError             | `new TypeError()`                   | `'TypeError'`         |              |\n| SyntaxError           | `new SyntaxError()`                 | `'SyntaxError'`       |              |\n| ReferenceError        | `new ReferenceError()`              | `'ReferenceError'`    |              |\n| URIError              | `new URIError()`                    | `'URIError'`          |              |\n| RangeError            | `new RangeError()`                  | `'RangeError'`        |              |\n| EvalError             | `new EvalError()`                   | `'EvalError'`         |              |\n| Math                  | `Math`                              | `'Math'`              |              |\n| JSON                  | `JSON`                              | `'JSON'`              | IE8+         |\n| arguments             | `(function(){return arguments;})()` | `'Arguments'`         | IE9+         |\n| custom constructor    | `new Beep()`                        | `'Beep'`              |              |\n| anonymous constructor | `new (function(){})()`              | `''`                  |              |\n\n\u003c/section\u003e\n\n\u003c!-- /.usage --\u003e\n\n\u003csection class=\"notes\"\u003e\n\n## Notes\n\n-   If a value's constructor is an anonymous `function`, the implementation returns an empty `string`.\n\n    \u003c!-- eslint-disable no-restricted-syntax, func-style, func-names --\u003e\n\n    ```javascript\n    var Beep = function () {\n        return this;\n    };\n\n    var v = constructorName( new Beep() );\n    // returns ''\n    ```\n\n\u003c/section\u003e\n\n\u003c!-- /.notes --\u003e\n\n\u003csection class=\"examples\"\u003e\n\n## Examples\n\n\u003c!-- TODO: update once have Buffer wrapper --\u003e\n\n\u003c!-- eslint no-undef: \"error\" --\u003e\n\n\u003c!-- eslint-disable no-restricted-syntax, no-buffer-constructor, func-style, func-names --\u003e\n\n```javascript\nvar Float32Array = require( '@stdlib/array-float32' );\nvar Float64Array = require( '@stdlib/array-float64' );\nvar Int8Array = require( '@stdlib/array-int8' );\nvar Int16Array = require( '@stdlib/array-int16' );\nvar Int32Array = require( '@stdlib/array-int32' );\nvar Uint8Array = require( '@stdlib/array-uint8' );\nvar Uint8ClampedArray = require( '@stdlib/array-uint8c' );\nvar Uint16Array = require( '@stdlib/array-uint16' );\nvar Uint32Array = require( '@stdlib/array-uint32' );\nvar ArrayBuffer = require( '@stdlib/array-buffer' );\nvar Buffer = require( '@stdlib/buffer-ctor' );\nvar Symbol = require( '@stdlib/symbol-ctor' );\nvar constructorName = require( '@stdlib/utils-constructor-name' );\n\nfunction noop() {\n    // Do nothing...\n}\n\nvar v = constructorName( 'a' );\n// returns 'String'\n\nv = constructorName( 5 );\n// returns 'Number'\n\nv = constructorName( NaN );\n// returns 'Number'\n\nv = constructorName( null );\n// returns 'Null'\n\nv = constructorName( void 0 );\n// returns 'Undefined'\n\nv = constructorName( true );\n// returns 'Boolean'\n\nv = constructorName( false );\n// returns 'Boolean'\n\nv = constructorName( {} );\n// returns 'Object'\n\nv = constructorName( [] );\n// returns 'Array'\n\nv = constructorName( noop );\n// returns 'Function'\n\nv = constructorName( /./ );\n// returns 'RegExp'\n\nv = constructorName( new Date() );\n// returns 'Date'\n\nv = constructorName( new Map() );\n// returns 'Map'\n\nv = constructorName( new WeakMap() );\n// returns 'WeakMap'\n\nv = constructorName( new Set() );\n// returns 'Set'\n\nv = constructorName( new WeakSet() );\n// returns 'WeakSet'\n\nv = constructorName( Symbol( 'beep' ) );\n// returns 'Symbol'\n\nv = constructorName( new Error() );\n// returns 'Error'\n\nv = constructorName( new TypeError() );\n// returns 'TypeError'\n\nv = constructorName( new SyntaxError() );\n// returns 'SyntaxError'\n\nv = constructorName( new URIError() );\n// returns 'URIError'\n\nv = constructorName( new RangeError() );\n// returns 'RangeError'\n\nv = constructorName( new ReferenceError() );\n// returns 'ReferenceError'\n\nv = constructorName( new EvalError() );\n// returns 'EvalError'\n\nv = constructorName( new Int8Array() );\n// returns 'Int8Array'\n\nv = constructorName( new Uint8Array() );\n// returns 'Uint8Array'\n\nv = constructorName( new Uint8ClampedArray() );\n// returns 'Uint8ClampedArray'\n\nv = constructorName( new Int16Array() );\n// returns 'Int16Array'\n\nv = constructorName( new Uint16Array() );\n// returns 'Uint16Array'\n\nv = constructorName( new Int32Array() );\n// returns 'Int32Array'\n\nv = constructorName( new Uint32Array() );\n// returns 'Uint32Array'\n\nv = constructorName( new Float32Array() );\n// returns 'Float32Array'\n\nv = constructorName( new Float64Array() );\n// returns 'Float64Array'\n\nv = constructorName( new ArrayBuffer() );\n// returns 'ArrayBuffer'\n\nv = constructorName( new Buffer( 'beep' ) );\n// returns 'Buffer'\n\nv = constructorName( Math );\n// returns 'Math'\n\nv = constructorName( JSON );\n// returns 'JSON'\n\nfunction Person1() {\n    return this;\n}\nv = constructorName( new Person1() );\n// returns 'Person1'\n\nvar Person2 = function () {\n    return this;\n};\nv = constructorName( new Person2() );\n// returns ''\n```\n\n\u003c/section\u003e\n\n\u003c!-- /.examples --\u003e\n\n\u003c!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. --\u003e\n\n\u003csection class=\"related\"\u003e\n\n* * *\n\n## See Also\n\n-   \u003cspan class=\"package-name\"\u003e[`@stdlib/utils-function-name`][@stdlib/utils/function-name]\u003c/span\u003e\u003cspan class=\"delimiter\"\u003e: \u003c/span\u003e\u003cspan class=\"description\"\u003edetermine a function's name.\u003c/span\u003e\n\n\u003c/section\u003e\n\n\u003c!-- /.related --\u003e\n\n\u003c!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --\u003e\n\n\n\u003csection class=\"main-repo\" \u003e\n\n* * *\n\n## Notice\n\nThis package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.\n\nFor more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].\n\n#### Community\n\n[![Chat][chat-image]][chat-url]\n\n---\n\n## License\n\nSee [LICENSE][stdlib-license].\n\n\n## Copyright\n\nCopyright \u0026copy; 2016-2025. The Stdlib [Authors][stdlib-authors].\n\n\u003c/section\u003e\n\n\u003c!-- /.stdlib --\u003e\n\n\u003c!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --\u003e\n\n\u003csection class=\"links\"\u003e\n\n[npm-image]: http://img.shields.io/npm/v/@stdlib/utils-constructor-name.svg\n[npm-url]: https://npmjs.org/package/@stdlib/utils-constructor-name\n\n[test-image]: https://github.com/stdlib-js/utils-constructor-name/actions/workflows/test.yml/badge.svg?branch=main\n[test-url]: https://github.com/stdlib-js/utils-constructor-name/actions/workflows/test.yml?query=branch:main\n\n[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/utils-constructor-name/main.svg\n[coverage-url]: https://codecov.io/github/stdlib-js/utils-constructor-name?branch=main\n\n\u003c!--\n\n[dependencies-image]: https://img.shields.io/david/stdlib-js/utils-constructor-name.svg\n[dependencies-url]: https://david-dm.org/stdlib-js/utils-constructor-name/main\n\n--\u003e\n\n[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg\n[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im\n\n[stdlib]: https://github.com/stdlib-js/stdlib\n\n[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors\n\n[umd]: https://github.com/umdjs/umd\n[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules\n\n[deno-url]: https://github.com/stdlib-js/utils-constructor-name/tree/deno\n[deno-readme]: https://github.com/stdlib-js/utils-constructor-name/blob/deno/README.md\n[umd-url]: https://github.com/stdlib-js/utils-constructor-name/tree/umd\n[umd-readme]: https://github.com/stdlib-js/utils-constructor-name/blob/umd/README.md\n[esm-url]: https://github.com/stdlib-js/utils-constructor-name/tree/esm\n[esm-readme]: https://github.com/stdlib-js/utils-constructor-name/blob/esm/README.md\n[branches-url]: https://github.com/stdlib-js/utils-constructor-name/blob/main/branches.md\n\n[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/utils-constructor-name/main/LICENSE\n\n\u003c!-- \u003crelated-links\u003e --\u003e\n\n[@stdlib/utils/function-name]: https://github.com/stdlib-js/utils-function-name\n\n\u003c!-- \u003c/related-links\u003e --\u003e\n\n\u003c/section\u003e\n\n\u003c!-- /.links --\u003e\n","funding_links":["https://github.com/sponsors/stdlib-js","https://opencollective.com/stdlib","https://tidelift.com/funding/github/npm/@stdlib/stdlib"],"categories":[],"sub_categories":[],"project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fstdlib-js%2Futils-constructor-name","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fstdlib-js%2Futils-constructor-name","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fstdlib-js%2Futils-constructor-name/lists"}