Object
Summary
Provides functionality common to all JavaScript objects.
Syntax
obj = new Object( [ value ] )
- obj
- Required. The variable name to which the Object object is assigned.
- value
- Optional. Any one of the JavaScript primitive data types (Number, Boolean, or String). If value is an object, the object is returned unmodified. If value is null , undefined , or not supplied, an object with no content is created.
Remarks
The Object object is contained in all other JavaScript objects; all of its methods and properties are available in all other objects. The methods can be redefined in user-defined objects, and are called by JavaScript at appropriate times. The toString method is an example of a frequently redefined Object method.
In this language reference, the description of each Object method includes both default and object-specific implementation information for the intrinsic JavaScript objects.
Properties
The following table lists properties of the Object Object.
| Property | Description |
|---|---|
| constructor Property | Specifies the function that creates an object. |
| prototype Property | Returns a reference to the prototype for a class of objects. |
Functions
The following table lists functions of the Object Object.
| Function | Description |
|---|---|
| Object.create Function | Creates an object that has a specified prototype, and that optionally contains specified properties. |
| Object.defineProperties Function | Adds one or more properties to an object, and/or modifies attributes of existing properties. |
| Object.defineProperty Function | Adds a property to an object, or modifies attributes of an existing property. |
| Object.freeze Function | Prevents the modification of existing property attributes and values, and prevents the addition of new properties. |
| Object.getOwnPropertyDescriptor Function | Returns the definition of a data property or an accessor property. |
| Object.getOwnPropertyNames Function | Returns the names of the properties and methods of an object. |
| Object.getPrototypeOf Function | Returns the prototype of an object. |
| Object.isExtensible Function | Returns a value that indicates whether new properties can be added to an object. |
| Object.isFrozen Function | Returns true if existing property attributes and values cannot be modified in an object and new properties cannot be added to the object. |
| Object.isSealed Function | Returns true if existing property attributes cannot be modified in an object and new properties cannot be added to the object. |
| Object.keys Function | Returns the names of the enumerable properties and methods of an object. |
| Object.preventExtensions Function | Prevents the addition of new properties to an object. |
| Object.seal Function | Prevents the modification of attributes of existing properties, and prevents the addition of new properties. |
Methods
The following table lists methods of the Object Object.
| Method | Description |
|---|---|
| hasOwnProperty method | Returns a Boolean value that indicates whether an object has a property with the specified name. |
| isPrototypeOf method | Returns a Boolean value that indicates whether an object exists in another object’s prototype hierarchy. |
| propertyIsEnumerable method | Returns a Boolean value that indicates whether a specified property is part of an object and whether it is enumerable. |
| toLocaleString method | Returns an object converted to a string based on the current locale. |
| toString method | Returns a string representation of an object. |
| valueOf method | Returns the primitive value of the specified object. |
See also
Other articles
Attributions
Microsoft Developer Network: Article