The values of some properties can change. Properties can be fixed or dynamic . Fixed properties are declared as members of a class definition and are created at the time the object is constructed. Dynamic properties can be added to an object at any time after the object was created. All JavaScript 1.5 properties are dynamic.
Properties can have attributes .
Fixed properties inherit their attributes from the corresponding members. A property name identifies a property of an instance and consists of a namespace N , an identifier id , and a class C . If the property is fixed , then C is the class in which the corresponding member is defined. If the property is dynamic , then C is the instance's most derived class. If the member is defined in an interface, then C is a class that implements that interface.