Determine a function's name.
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> Determine a function's name.
``bash`
npm install @stdlib/utils-function-name
`javascript`
var functionName = require( '@stdlib/utils-function-name' );
#### functionName( fcn )
Returns the name of a function.
`javascript`
var v = functionName( Math.sqrt );
// returns 'sqrt'
If provided an anonymous function, the function returns an empty string or the string "anonymous".
`javascript`
var v = functionName( function () {} );
// returns '' || 'anonymous'
If provided a value which is not a function, the function throws a TypeError.
`javascript`
try {
functionName( 'beep' );
// throws error...
} catch ( err ) {
console.error( err );
}
- For more information regarding the naming of anonymous functions, see
- [Function Names in ES6][2ality-function-names]
- Webkit bug [7726][webkit-bug-7726]
- [MDN][mdn-function-name]
`javascript
var Float64Array = require( '@stdlib/array-float64' );
var Buffer = require( '@stdlib/buffer-ctor' );
var Number = require( '@stdlib/number-ctor' );
var Boolean = require( '@stdlib/boolean-ctor' );
var Function = require( '@stdlib/function-ctor' );
var functionName = require( '@stdlib/utils-function-name' );
var v = functionName( Math.sqrt );
// returns 'sqrt'
v = functionName( Float64Array );
// returns 'Float64Array'
v = functionName( Buffer );
// returns 'Buffer'
v = functionName( Date );
// returns 'Date'
v = functionName( String );
// returns 'String'
v = functionName( Boolean );
// returns 'Boolean'
v = functionName( Function );
// returns 'Function'
v = functionName( Number );
// returns 'Number'
v = functionName( function foo() {} );
// returns 'foo'
v = functionName( function () {} );
// returns '' || 'anonymous'
`
*
- [@stdlib/utils-constructor-name][@stdlib/utils/constructor-name]: determine the name of a value's constructor.
*
This 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.
For 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].
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---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/utils-function-name.svg
[npm-url]: https://npmjs.org/package/@stdlib/utils-function-name
[test-image]: https://github.com/stdlib-js/utils-function-name/actions/workflows/test.yml/badge.svg?branch=v0.2.3
[test-url]: https://github.com/stdlib-js/utils-function-name/actions/workflows/test.yml?query=branch:v0.2.3
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/utils-function-name/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/utils-function-name?branch=main
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[chat-url]: https://stdlib.zulipchat.com
[stdlib]: https://github.com/stdlib-js/stdlib
[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors
[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules
[deno-url]: https://github.com/stdlib-js/utils-function-name/tree/deno
[deno-readme]: https://github.com/stdlib-js/utils-function-name/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/utils-function-name/tree/umd
[umd-readme]: https://github.com/stdlib-js/utils-function-name/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/utils-function-name/tree/esm
[esm-readme]: https://github.com/stdlib-js/utils-function-name/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/utils-function-name/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/utils-function-name/main/LICENSE
[2ality-function-names]: http://www.2ality.com/2015/09/function-names-es6.html
[webkit-bug-7726]: https://bugs.webkit.org/show_bug.cgi?id=7726
[mdn-function-name]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/name
[@stdlib/utils/constructor-name]: https://www.npmjs.com/package/@stdlib/utils-constructor-name