Name
Object.hasOwnProperty( ) — check whether a property is inherited
Availability
JavaScript 1.5; JScript 5.5; ECMAScript v3
Synopsis
object
.hasOwnProperty(propname
)
Arguments
-
propname
A string that contains the name of a property of
object
.
Returns
true
if
object
has a noninherited property with
the name specified by propname
. Returns
false
if object
does
not have a property with the specified name or if it inherits that
property from its prototype object.
Description
As explained in Chapter 8, JavaScript objects may
have properties of their own, and they may also inherit properties
from their prototype object. The hasOwnProperty( )
method provides a way to distinguish between inherited properties and
noninherited local properties.
Example
var o = new Object( ); // Create an object o.x = 3.14; // Define a noninherited local property o.hasOwnProperty("x"); // Returns true: x is a local property of o o.hasOwnProperty("y"); // Returns false: o doesn't have a property y o.hasOwnProperty("toString"); // Returns false: toString property is inherited
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