Section 24.140. Object: a superclass that contains features of all JavaScript objects

24.140. Object: a superclass that contains features of all JavaScript objects

ECMAScript v1

24.140.1. Constructor

 new Object( ) new Object(value) 

24.140.1.1. Arguments

value

This optional argument specifies a primitive JavaScript valuea number, boolean, or stringthat is to be converted to a Number, Boolean, or String object.

24.140.1.2. Returns

If no value argument is passed, this constructor returns a newly created Object instance. If a primitive value argument is specified, the constructor creates and returns a Number, Boolean, or String object wrapper for the primitive value. When the Object( ) constructor is called as a function, without the new operator, it behaves just as it does when used with the new operator.

24.140.2. Properties

constructor

A reference to the JavaScript function that was the constructor for the object.

24.140.3. Methods

hasOwnProperty( )

Checks whether an object has a locally defined (noninherited) property with a specified name.

isPrototypeOf( )

Checks whether this object is the prototype object of a specified object.

propertyIsEnumerable( )

Checks whether a named property exists and would be enumerated by a for/in loop.

toLocaleString( )

Returns a localized string representation of the object. The default implementation of this method simply calls toString( ), but subclasses may override it to provide localization.

toString( )

Returns a string representation of the object. The implementation of this method provided by the Object class is quite generic and does not provide much useful information. Subclasses of Object typically override this method by defining their own toString( ) method, which produces more useful output.

valueOf( )

Returns the primitive value of the object, if any. For objects of type Object, this method simply returns the object itself. Subclasses of Object, such as Number and Boolean, override this method to return the primitive value associated with the object.

24.140.4. Description

The Object class is a built-in datatype of the JavaScript language. It serves as the superclass for all other JavaScript objects; therefore, methods and behavior of the Object class are inherited by all other objects. The basic behavior of objects in JavaScript is explained in Chapter 7.

In addition to the Object( ) constructor shown above, objects can also be created and initialized using the Object literal syntax described in Chapter 7.

24.140.5. See Also

Array, Boolean, Function, Function.prototype, Number, String; Chapter 7