generics

Hi people.
First of all,  excuse me my clumsy english.

Here is the question i will be really glad to get the answer for -
Array and String generics in firefox's implementation of javascript - i can't get it -
are they in fact just functions wrapped in namespaces?
Shall I get the same result if, for example, i use smth like:

NameSpace =
{
  forEach:function(){..}
}