Object

Installation

npm install @stdlib/object-ctor

Usage

var Object = require( '@stdlib/object-ctor' );

Object( value )

Returns a new object.

var o = new Object( null );
// returns {}

Properties

Object.prototype.constructor

Property whose value is a reference to the constructor function that created the instance object.

var o = new Object( null );
var ctr = o.constructor;
// returns Object

Methods

Object.assign( target, ...sources )

Assigns enumerable properties of one or more source objects to a target object.

var o = Object.assign( {}, { 'a': 1, 'b': 2 } );
// returns { 'a': 1, 'b': 2 }

Object.create( prototype, properties )

Returns a new object with the given prototype and properties.

var o = Object.create( null, {
    'a': {
        'value': 1
    },
    'b': {
        'value': 2
    }
});
// returns { 'a': 1, 'b': 2 }

function Person( first, last ) {
    this.first = first;
    this.last = last;
}

var p = Object.create( Person.prototype, {
    'first': {
        'value': 'Jane'
    },
    'last': {
        'value': 'Doe'
    }
});
// returns Person { 'first': 'Jane', 'last': 'Doe' }

Object.defineProperties( target, properties )

Defines new or modifies existing properties directly on an object, returning the object.

var o = Object.defineProperties( {}, {
    'a': {
        'value': 1
    },
    'b': {
        'value': 2
    }
});
// returns { 'a': 1, 'b': 2 }

Object.defineProperty( target, property, descriptor )

Defines a new property directly on an object, or modifies an existing property on an object, and returns the object.

var o = Object.defineProperty( {}, 'a', {
    'value': 1,
    'writable': true,
    'enumerable': true,
    'configurable': true
});
// returns { 'a': 1 }

Object.entries( obj )

Returns an array of a given object's own enumerable string-keyed property entries, i.e. [key, value] pairs.

var o = { 'a': 1, 'b': 2 };
var arr = Object.entries( o );
// e.g., returns [ [ 'a', 1 ], [ 'b', 2 ] ]

Object.freeze( o )

Freezes an object. A frozen object can no longer be changed; freezing an object prevents new properties from being added to it, existing properties from being removed, and existing properties from being changed.

var o = { 'a': 1 };
Object.freeze( o );
// returns { 'a': 1 }

o.b = 1;
var v = o.b;
// returns undefined

Object.getOwnPropertyDescriptor( o, p )

Returns an object that contains the properties of the given object.

var o = { 'a': 1 };
var d = Object.getOwnPropertyDescriptor( o, 'a' );
// returns { 'value': 1, 'writable': true, 'enumerable': true, 'configurable': true }

Object.getOwnPropertyDescriptors( o )

Returns an object whose properties are the result of calling Object.getOwnPropertyDescriptor() on every property of the given object.

var o = { 'a': 1, 'b': 2 };
var d = Object.getOwnPropertyDescriptors( o );
// returns { 'a': { 'value': 1, 'writable': true, 'enumerable': true, 'configurable': true }, 'b': { 'value': 2, 'writable': true, 'enumerable': true, 'configurable': true } }

Object.getOwnPropertyNames( o )

Returns an array of a given object's own property names.

var o = { 'a': 1, 'b': 2 };
var arr = Object.getOwnPropertyNames( o );
// e.g., returns [ 'a', 'b' ]

Object.getOwnPropertySymbols( o )

Returns an array of a given object's own property symbols.

var o = { 'a': 1 };
o[ Symbol( 'b' ) ] = 2;
var arr = Object.getOwnPropertySymbols( o );
// returns [ Symbol(b) ]

Object.getPrototypeOf( o )

Returns the prototype of an object.

var o = { 'a': 1 };
var p = Object.getPrototypeOf( o );
// returns {}

Object.hasOwn( o, p )

Returns a boolean indicating whether an object has a property with the specified name.

var o = { 'a': 1 };
var b = Object.hasOwn( o, 'b' );
// returns false

Object.prototype.hasOwnProperty( p )

Returns a boolean indicating whether an object has a property with the specified name.

var o = { 'a': 1 };
var b = o.hasOwnProperty( 'a' );
// returns true

Object.is( value1, value2 )

Returns a boolean indicating whether two values are the same value.

var b = Object.is( 1, 1 );
// returns true

b = Object.is( 1, '1' );
// returns false

Object.isExtensible( o )

Returns a boolean indicating whether an object is extensible (whether new properties can be added to it).

var o = { 'a': 1 };
var b = Object.isExtensible( o );
// returns true

Object.preventExtensions( o );
b = Object.isExtensible( o );
// returns false

Object.isFrozen( o )

Returns a boolean indicating whether an object is frozen. Frozen objects can no longer be changed; freezing an object prevents new properties from being added to it, existing properties from being removed, and existing properties from being changed.

var o = { 'a': 1 };
var b = Object.isFrozen( o );
// returns false

Object.freeze( o );
b = Object.isFrozen( o );
// returns true

Object.prototype.isPrototypeOf( o )

Returns a boolean indicating whether an object is in the prototype chain of another object.

var o = { 'a': 1 };
var p = { '__proto__': o };
var b = o.isPrototypeOf( p );
// returns true

Object.isSealed( o )

Returns a boolean indicating whether an object is sealed. An object is sealed if it is not extensible and all of its properties are non-configurable.

var o = { 'a': 1 };
var b = Object.isSealed( o );
// returns false

Object.seal( o );
b = Object.isSealed( o );
// returns true

Object.keys( o )

Returns an array of a given object's own enumerable property names.

var o = { 'a': 1, 'b': 2 };
var arr = Object.keys( o );
// e.g., returns [ 'a', 'b' ]

Object.preventExtensions( o )

Prevents new properties from being added to an object.

var o = { 'a': 1 };
Object.preventExtensions( o );
o.b = 2;
var b = ( o.b === void 0 );
// returns true

o.a = 3;
b = ( o.a === 3 );
// returns true

Object.prototype.propertyIsEnumerable( p )

Returns a boolean indicating whether a property is enumerable.

var o = { 'a': 1 };
var b = o.propertyIsEnumerable( 'a' );
// returns true

var arr = [ 1, 2, 3 ];
b = arr.propertyIsEnumerable( 'length' );
// returns false

Object.seal( o )

Seals an object, preventing new properties from being added to it (i.e., making it non extensible) and marking all existing properties as non-configurable.

var o = { 'a': 1 };
Object.seal( o );

o.b = 2;
var b = ( o.b === void 0 );
// returns true

Object.setPrototypeOf( o, proto )

Sets the prototype of an object.

var o = { 'a': 1 };
var p = { 'b': 2 };
Object.setPrototypeOf( o, p );

var b = ( o.b === 2 );
// returns true

Object.prototype.toLocaleString()

Returns a string representing the object.

var o = { 'a': 1 };
var str = o.toLocaleString();
// returns <string>

Object.prototype.toString()

Returns a string representing the object.

var o = { 'a': 1 };
var str = o.toString();
// returns <string>

Object.prototype.valueOf()

Returns the primitive value of the object.

var o = {};
var v = o.valueOf();
// returns {}

Object.values( o )

Returns an array of a given object's own enumerable property values.

var o = { 'a': 1, 'b': 2 };
var arr = Object.values( o );
// e.g., returns [ 1, 2 ]

Notes

• If provided null or undefined, the function returns an empty object.
• If provided an existing object, the function returns the input value unchanged.
• Otherwise, if provided any other value (e.g., a number, string, etc), the function will return an object of the corresponding type.

Examples

var Object = require( '@stdlib/object-ctor' );

var values = [
    '5',
    5,
    true,
    false,
    null,
    void 0,
    [],
    {}
];

var i;
for ( i = 0; i < values.length; i++ ) {
    console.log( new Object( values[ i ] ) );
}

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.