@stdlib/utils-constructor-name
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0.2.1 • Public • Published
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Constructor Name

NPM version Build Status Coverage Status

Determine the name of a value's constructor.

Installation

npm install @stdlib/utils-constructor-name

Usage

var constructorName = require( '@stdlib/utils-constructor-name' );

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

var Float32Array = require( '@stdlib/array-float32' );
var Float64Array = require( '@stdlib/array-float64' );
var Int8Array = require( '@stdlib/array-int8' );
var Int16Array = require( '@stdlib/array-int16' );
var Int32Array = require( '@stdlib/array-int32' );
var Uint8Array = require( '@stdlib/array-uint8' );
var Uint8ClampedArray = require( '@stdlib/array-uint8c' );
var Uint16Array = require( '@stdlib/array-uint16' );
var Uint32Array = require( '@stdlib/array-uint32' );
var ArrayBuffer = require( '@stdlib/array-buffer' );
var Buffer = require( '@stdlib/buffer-ctor' );
var Symbol = require( '@stdlib/symbol-ctor' );
var constructorName = require( '@stdlib/utils-constructor-name' );

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


Notice

This package is part of 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, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.

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npm i @stdlib/utils-constructor-name

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