Name
Object.hasOwnProperty() — check whether a property is inherited
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 inherited
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