Name
Object.getOwnPropertyDescriptor() — query property attributes
Availability
ECMAScript 5
Synopsis
Object
.
getOwnPropertyDescriptor
(
o
,
name
)
Arguments
o
The object that is to have its property attributes queried.
name
The name of the property (or index of the array element) to query.
Returns
A property descriptor object for the specified property of
the specified object, or undefined
if no such property
exists.
Description
Object.getOwnPropertyDescriptor()
returns
a property descriptor for the specified property of the specified
object. A property descriptor is an object that describes the
attributes and value of a property. See the sub-section below for
complete details. Note that this is not a method to be invoked on an
object: it is a global function and you must pass an object to
it.
Property Descriptors
A property descriptor is an ordinary JavaScript object that describes the attributes (and sometimes the value) of a property. There are two kinds of JavaScript properties. A data property has a value and three attributes: enumerable, writable, and configurable. An accessor property has a getter and/or a setter method as well as enumerable and configurable attributes.
The descriptor for a data property looks like this:
{
value
:
/* any JavaScript value */
,
writable
:
/* true or false */
,
enumerable
:
/* true or false */
,
configurable
:
/* true or false */
}
The descriptor for an accessor property looks like this:
{
get
:
/* function or undefined: replaces the property value */
,
set
:
/* function or ...
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