Javascript [Electronic resources] : The Definitive Guide (4th Edition) نسخه متنی

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

See Also

Function.prototype, Object.propertyIsEnumerable( ); Chapter 8