my %hash = (
  opt1 => [qw/these are the options of the dynamic select 
      box when opt1 in the first is selected/],
   #...
);
my $js = 'var items = new Array();'.
  map {
    "items['$_'] = new Array('".
      join("','",map quotemeta => @{$hash{$_}}).
     "');"
   } keys %hash;