The Object
constructor creates an object wrapper.
Syntax
// Object initialiser or literal { [ nameValuePair1[, nameValuePair2[, ...nameValuePairN] ] ] } // Called as a constructor new Object([value])
Parameters
nameValuePair1, nameValuePair2, ... nameValuePairN
- Pairs of names (strings) and values (any value) where the name is separated from the value by a colon.
value
- Any value.
Description
The Object
constructor creates an object wrapper for the given value. If the value is {{jsxref("null")}} or {{jsxref("undefined")}}, it will create and return an empty object, otherwise, it will return an object of a Type that corresponds to the given value. If the value is an object already, it will return the value.
When called in a non-constructor context, Object
behaves identically to new Object()
.
See also the object initializer / literal syntax.
Properties of the Object
constructor
Object.length
- Has a value of 1.
- {{jsxref("Object.prototype")}}
- Allows the addition of properties to all objects of type Object.
Methods of the Object
constructor
- {{jsxref("Object.assign()")}}
- Creates a new object by copying the values of all enumerable own properties from one or more source objects to a target object.
- {{jsxref("Object.create()")}}
- Creates a new object with the specified prototype object and properties.
- {{jsxref("Object.defineProperty()")}}
- Adds the named property described by a given descriptor to an object.
- {{jsxref("Object.defineProperties()")}}
- Adds the named properties described by the given descriptors to an object.
- {{jsxref("Object.entries()")}} {{experimental_inline}}
- Returns an array of a given object's own enumerable property
[key, value]
pairs. - {{jsxref("Object.freeze()")}}
- Freezes an object: other code can't delete or change any properties.
- {{jsxref("Object.getOwnPropertyDescriptor()")}}
- Returns a property descriptor for a named property on an object.
- {{jsxref("Object.getOwnPropertyNames()")}}
- Returns an array containing the names of all of the given object's own enumerable and non-enumerable properties.
- {{jsxref("Object.getOwnPropertySymbols()")}}
- Returns an array of all symbol properties found directly upon a given object.
- {{jsxref("Object.getPrototypeOf()")}}
- Returns the prototype of the specified object.
- {{jsxref("Object.is()")}}
- Compares if two values are distinguishable (ie. the same)
- {{jsxref("Object.isExtensible()")}}
- Determines if extending of an object is allowed.
- {{jsxref("Object.isFrozen()")}}
- Determines if an object was frozen.
- {{jsxref("Object.isSealed()")}}
- Determines if an object is sealed.
- {{jsxref("Object.keys()")}}
- Returns an array containing the names of all of the given object's own enumerable properties.
- {{jsxref("Object.preventExtensions()")}}
- Prevents any extensions of an object.
- {{jsxref("Object.seal()")}}
- Prevents other code from deleting properties of an object.
- {{jsxref("Object.setPrototypeOf()")}}
- Sets the prototype (i.e., the internal
[[Prototype]]
property) - {{jsxref("Object.values()")}} {{experimental_inline}}
- Returns an array of a given object's own enumerable values.
Object
instances and Object
prototype object
All objects in JavaScript are descended from Object
; all objects inherit methods and properties from {{jsxref("Object.prototype")}}, although they may be overridden. For example, other constructors' prototypes override the constructor
property and provide their own toString()
methods. Changes to the Object
prototype object are propagated to all objects unless the properties and methods subject to those changes are overridden further along the prototype chain.
Properties
Methods
Examples
Using Object
given undefined
and null
types
The following examples store an empty Object
object in o
:
var o = new Object();
var o = new Object(undefined);
var o = new Object(null);
Using Object
to create Boolean
objects
The following examples store {{jsxref("Boolean")}} objects in o
:
// equivalent to o = new Boolean(true); var o = new Object(true);
// equivalent to o = new Boolean(false); var o = new Object(Boolean());
Specifications
Specification | Status | Comment |
---|---|---|
{{SpecName('ES1')}} | {{Spec2('ES1')}} | Initial definition. Implemented in JavaScript 1.0. |
{{SpecName('ES5.1', '#sec-15.2', 'Object')}} | {{Spec2('ES5.1')}} | |
{{SpecName('ES6', '#sec-object-objects', 'Object')}} | {{Spec2('ES6')}} | Added Object.assign, Object.getOwnPropertySymbols, Object.setPrototypeOf |
{{SpecName('ESDraft', '#sec-object-objects', 'Object')}} | {{Spec2('ESDraft')}} | Added Object.entries and Object.values. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} |