Obsolete since JSAPI 16
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.
Internal use only. The type of JavaScript object properties, used by the JSObjectOps layer.
Syntax
struct JSProperty {
    jsid id;
};
Description
JSProperty is the abstract base class of all object properties. It is used internally in JSObjectOps.lookupProperty, getAttributes, setAttributes, and dropProperty.