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stdlib/lib/node_modules/@stdlib/utils/native-class at develop · stdlib-js/stdlib

Determine the specification defined classification of an object.

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