I dive out the problem might be that firefox 7 does not support anonymous functions.

sub browser {
    my ($self,$repl) = @_;
    $repl ||= $self->repl;   
    print "repl: $repl\n";
    return $repl->declare(<<'JS')->();
    function () {      
        
        var wm = Components.classes["@mozilla.org/appshell/window-medi
+ator;1"]
                           .getService(Components.interfaces.nsIWindow
+Mediator);
        var win = wm.getMostRecentWindow('navigator:browser');
        if (! win) {
          // No browser windows are open, so open a new one.
          win = window.open('about:blank');
        };
        return win.gBrowser
        //return win.getBrowser()
}    

    
JS
};



sub declare {
    my ($self,$js,$context) = @_;
    print "1:$self; 2:$js;3:$context\n ";
  
    if (! $self->{functions}->{$js}) {
        $self->{functions}->{$js} = $self->expr($js);
        # Weaken the backlink of the function
        my $res = $self->{functions}->{$js};
        my $ref = ref $res;
        bless $res, "$ref\::HashAccess";
        weaken $res->{bridge};
        $res->{return_context} = $context;
        bless $res => $ref;
    };

    $self->{functions}->{$js}

};
[download]

If I manually change the function () to function abc(), then repl can not get any references:

Can't bless non-reference value at C:/Perl/site/lib/MozRepl/RemoteObject.pm

How to solve this issue?

Ouch! I'm sorry - I encountered the same issue and locally already fixed it without bumping the MozRepl::RemoteObject version and without releasing it to CPAN.

If you're in a bind, the current version from Github should make "everything just work again", even with Firefox 7.

The (ugly) change is that

eval "function() {}";
[download]

does not return an anonymous function in Javascript (on Firefox 7) anymore. The change is to use:

eval "expr_=function() {}; expr";
[download]

Update: Now released as v0.28 on CPAN.

The (ugly) change is that eval "function() {}"; does not return an anonymous function in Javascript (on Firefox 7) anymore

How odd. I remember that being a bug once in firefox2/3

What if you use return function(){};?

I dive out the problem might be that firefox 7 does not support anonymous functions.

No, firefox 7 supports and depends on anonymous functions

If I manually change the function () to function abc(), then repl can not get any references

:) yeah, don't do that

You're essentially changing return sub { print "call me" }; to sub named { print "call me" };

"sub {}" returns a function, but "sub name {}" returns nothing.

You're barking up the wrong tree :)