stdlib-js/utils-native-class

Determine the specification defined classification of an object.

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!

Native Class

Determine the specification defined classification of an object.

Installation

npm install @stdlib/utils-native-class

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To 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.

Usage

var nativeClass = require( '@stdlib/utils-native-class' );

nativeClass( value )

Returns a string value indicating a specification defined classification of an object.

var str = nativeClass( 'a' );
// returns '[object String]'

str = nativeClass( 5 );
// returns '[object Number]'

function Beep() {
    return this;
}
str = nativeClass( new Beep() );
// returns '[object Object]'

Notes

• The function is not robust for ES2015+ environments. In ES2015+, Symbol.toStringTag allows overriding the default description of an object.

  var toStr = Object.prototype.toString;
  
  var str = toStr.call( false );
  // returns '[object Boolean]'
  
  var o = {};
  str = toStr.call( o );
  // returns '[object Object]'
  
  // Mask the default description:
  o[ Symbol.toStringTag ] = 'Boolean';
  
  str = toStr.call( o );
  // returns '[object Boolean]'

  While measures are taken to uncover the default description, such measures can be thwarted. While this function remains useful for type-checking, be aware that value impersonation is possible. Prefer functions tailored to checking for particular value types, as specialized functions are better equipped to address Symbol.toStringTag.

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 Symbol = require( '@stdlib/symbol-ctor' );
var nativeClass = require( '@stdlib/utils-native-class' );

var str = nativeClass( 'a' );
// returns '[object String]'

str = nativeClass( 5 );
// returns '[object Number]'

str = nativeClass( NaN );
// returns '[object Number]'

str = nativeClass( null );
// returns '[object Null]'

str = nativeClass( void 0 );
// returns '[object Undefined]'

str = nativeClass( true );
// returns '[object Boolean]'

str = nativeClass( false );
// returns '[object Boolean]'

str = nativeClass( {} );
// returns '[object Object]'

str = nativeClass( [] );
// returns '[object Array]'

str = nativeClass( function noop() {} );
// returns '[object Function]'

str = nativeClass( /./ );
// returns '[object RegExp]'

str = nativeClass( new Date() );
// returns '[object Date]'

str = nativeClass( new Map() );
// returns '[object Map]'

str = nativeClass( new WeakMap() );
// returns '[object WeakMap]'

str = nativeClass( new Set() );
// returns '[object Set]'

str = nativeClass( new WeakSet() );
// returns '[object WeakSet]'

str = nativeClass( Symbol( 'beep' ) );
// returns '[object Symbol]'

str = nativeClass( new Error() );
// returns '[object Error]'

str = nativeClass( new TypeError() );
// returns '[object Error]'

str = nativeClass( new SyntaxError() );
// returns '[object Error]'

str = nativeClass( new URIError() );
// returns '[object Error]'

str = nativeClass( new RangeError() );
// returns '[object Error]'

str = nativeClass( new ReferenceError() );
// returns '[object Error]'

str = nativeClass( new EvalError() );
// returns '[object Error]'

str = nativeClass( new Int8Array() );
// returns '[object Int8Array]'

str = nativeClass( new Uint8Array() );
// returns '[object Uint8Array]'

str = nativeClass( new Uint8ClampedArray() );
// returns '[object Uint8ClampedArray]'

str = nativeClass( new Int16Array() );
// returns '[object Int16Array]'

str = nativeClass( new Uint16Array() );
// returns '[object Uint16Array]'

str = nativeClass( new Int32Array() );
// returns '[object Int32Array]'

str = nativeClass( new Uint32Array() );
// returns '[object Uint32Array]'

str = nativeClass( new Float32Array() );
// returns '[object Float32Array]'

str = nativeClass( new Float64Array() );
// returns '[object Float64Array]'

str = nativeClass( new ArrayBuffer() );
// returns '[object ArrayBuffer]'

str = nativeClass( Math );
// returns '[object Math]'

str = nativeClass( JSON );
// returns '[object JSON]'

function Person() {
    return this;
}
str = nativeClass( new Person() );
// returns '[object Object]'

---

See Also

• @stdlib/utils-constructor-name: determine the name of a value's constructor.
• @stdlib/utils-type-of: determine a value's type.

---

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

---

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.