August 2006
Intermediate to advanced
1018 pages
34h 13m
English
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Name
Object.hasOwnProperty( ): check whether a property is inherited — 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;
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 9, 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 inheritedSee Also
Function.prototype,
Object.propertyIsEnumerable( );
Chapter 9
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