|
February 24, 2001 Keeping the Prototyping Information Tips: February 2001
Yehuda Shiran, Ph.D.
|
|
JavaScript stores the prototyping relationship in an internal property of the object, __proto__ (two underscore characters at the front and two at the end.) Let's take an example:
The object
is executed. The value of __proto__ instructs JavaScript where to look for properties, when local definitions are not available. In the example above, the property borderWidth is not defined within the object Square. The browser looks for the value of __proto__, which is Shape, and then fetches the value of its borderWidth property. Being an internal property, most browsers will return undefined when asked to alert __proto__. Netscape 6, though, returns <object object>.
People who read this tip also read these tips: Look for similar tips by subject: |