README.md

About stdlib...

We 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.

The 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.

When 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.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

Constructor Name

Determine the name of a value's constructor.

Usage

import constructorName from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-constructor-name@deno/mod.js';

constructorName( value )

Returns the name of a value's constructor.

var v = constructorName( 'a' );
// returns 'String'

v = constructorName( 5 );
// returns 'Number'

function Beep() {
    return this;
}
v = constructorName( new Beep() );
// returns 'Beep'

description	value	constructor	notes
string	'beep'	'String'
number	5	'Number'
NaN	NaN	'Number'
infinity	+infinity/-infinity	'Number'
boolean	true/false	'Boolean'
null	null	'Null'
undefined	undefined	'Undefined'
array	['beep', 5]	'Array'
object	{'foo': 'bar'}	'Object'
function	function (){}	'Function'
symbol	Symbol()	'Symbol'	ES2015
regexp	/./	'RegExp'	Android 4.1+
String	new String('beep')	'String'
Number	new Number(5)	'Number'
Boolean	new Boolean(false)	'Boolean'
Object	new Object()	'Object'
Array	new Array()	'Array'
Int8Array	new Int8Array()	'Int8Array'
Uint8Array	new Uint8Array()	'Uint8Array'
Uint8ClampedArray	new Uint8ClampedArray()	'Uint8ClampedArray'
Int16Array	new Int16Array()	'Int16Array'
Uint16Array	new Uint16Array()	'Uint16Array'
Int32Array	new Int32Array()	'Int32Array'
Uint32Array	new Uint32Array()	'Uint32Array'
Float32Array	new Float32Array()	'Float32Array'
Float64Array	new Float64Array()	'Float64Array'
ArrayBuffer	new ArrayBuffer()	'ArrayBuffer'
Buffer	new Buffer()	'Buffer'	Node.js
Date	new Date()	'Date'
RegExp	new RegExp('.')	'RegExp'	Android 4.1+
Function	new Function('x', 'return x')	'Function'
Map	new Map()	'Map'	ES2015
WeakMap	new WeakMap()	'WeakMap'	ES2015
Set	new Set()	'Set'	ES2015
WeakSet	new WeakSet()	'WeakSet'	ES2015
Error	new Error()	'Error'
TypeError	new TypeError()	'TypeError'
SyntaxError	new SyntaxError()	'SyntaxError'
ReferenceError	new ReferenceError()	'ReferenceError'
URIError	new URIError()	'URIError'
RangeError	new RangeError()	'RangeError'
EvalError	new EvalError()	'EvalError'
Math	Math	'Math'
JSON	JSON	'JSON'	IE8+
arguments	(function(){return arguments;})()	'Arguments'	IE9+
custom constructor	new Beep()	'Beep'
anonymous constructor	new (function(){})()	''

Notes

• If a value's constructor is an anonymous function, the implementation returns an empty string.

  var Beep = function () {
      return this;
  };
  
  var v = constructorName( new Beep() );
  // returns ''

Examples

import Float32Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float32@deno/mod.js';
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@deno/mod.js';
import Int8Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-int8@deno/mod.js';
import Int16Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-int16@deno/mod.js';
import Int32Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-int32@deno/mod.js';
import Uint8Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-uint8@deno/mod.js';
import Uint8ClampedArray from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-uint8c@deno/mod.js';
import Uint16Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-uint16@deno/mod.js';
import Uint32Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-uint32@deno/mod.js';
import ArrayBuffer from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-buffer@deno/mod.js';
import Buffer from 'https://cdn.jsdelivr.net/gh/stdlib-js/buffer-ctor@deno/mod.js';
import Symbol from 'https://cdn.jsdelivr.net/gh/stdlib-js/symbol-ctor@deno/mod.js';
import constructorName from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-constructor-name@deno/mod.js';

function noop() {
    // Do nothing...
}

var v = constructorName( 'a' );
// returns 'String'

v = constructorName( 5 );
// returns 'Number'

v = constructorName( NaN );
// returns 'Number'

v = constructorName( null );
// returns 'Null'

v = constructorName( void 0 );
// returns 'Undefined'

v = constructorName( true );
// returns 'Boolean'

v = constructorName( false );
// returns 'Boolean'

v = constructorName( {} );
// returns 'Object'

v = constructorName( [] );
// returns 'Array'

v = constructorName( noop );
// returns 'Function'

v = constructorName( /./ );
// returns 'RegExp'

v = constructorName( new Date() );
// returns 'Date'

v = constructorName( new Map() );
// returns 'Map'

v = constructorName( new WeakMap() );
// returns 'WeakMap'

v = constructorName( new Set() );
// returns 'Set'

v = constructorName( new WeakSet() );
// returns 'WeakSet'

v = constructorName( Symbol( 'beep' ) );
// returns 'Symbol'

v = constructorName( new Error() );
// returns 'Error'

v = constructorName( new TypeError() );
// returns 'TypeError'

v = constructorName( new SyntaxError() );
// returns 'SyntaxError'

v = constructorName( new URIError() );
// returns 'URIError'

v = constructorName( new RangeError() );
// returns 'RangeError'

v = constructorName( new ReferenceError() );
// returns 'ReferenceError'

v = constructorName( new EvalError() );
// returns 'EvalError'

v = constructorName( new Int8Array() );
// returns 'Int8Array'

v = constructorName( new Uint8Array() );
// returns 'Uint8Array'

v = constructorName( new Uint8ClampedArray() );
// returns 'Uint8ClampedArray'

v = constructorName( new Int16Array() );
// returns 'Int16Array'

v = constructorName( new Uint16Array() );
// returns 'Uint16Array'

v = constructorName( new Int32Array() );
// returns 'Int32Array'

v = constructorName( new Uint32Array() );
// returns 'Uint32Array'

v = constructorName( new Float32Array() );
// returns 'Float32Array'

v = constructorName( new Float64Array() );
// returns 'Float64Array'

v = constructorName( new ArrayBuffer() );
// returns 'ArrayBuffer'

v = constructorName( new Buffer( 'beep' ) );
// returns 'Buffer'

v = constructorName( Math );
// returns 'Math'

v = constructorName( JSON );
// returns 'JSON'

function Person1() {
    return this;
}
v = constructorName( new Person1() );
// returns 'Person1'

var Person2 = function () {
    return this;
};
v = constructorName( new Person2() );
// returns ''

---

See Also

• @stdlib/utils-function-name: determine a function's name.

---

Notice

This package is part of stdlib, a standard library 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, see the main project repository.

Community

---

License

See LICENSE.

Copyright

Copyright © 2016-2025. The Stdlib Authors.