Is there any method that is called or event that is dispatched right before an Element is cleaned up by the JavaScript garbage collector?

In Perl I would write:

package MyObj;

sub new {bless {}}

sub DESTROY {print "cleaning up @_\n"}

and then later:

{
    my $obj = MyObj->new;

    # do something with obj

}  # scope ends, and assuming there are no external references to $obj,
   #   the DESTROY method will be called before the object's memory is freed

My target platform is Firefox (and I have no need to support other browsers), so if there is only a Firefox specific way of doing this, that is fine.

And a little background: I am writing the Perl module XUL::Gui which serves as a bridge between Perl and Firefox, and I am currently working on plugging a few memory leaks related to DOM Elements sticking around forever, even after they are gone and no more references remain on the Perl side. So I am looking for ways to either figure out when JavaScript Elements will be destroyed, or a way to force JavaScript to cleanup an object.