use strict;
use warnings;
my %categories = ( A => [ 'B', 'Z' ], C => ['D', 'E'] );
my $category = param('category') || '';
my $subcategory = param('subcategory') || '';

use CGI qw/:standard/;;

# Generate javascript
print <<EOF;
<script language="javascript">
function catChange(newCat) {
    with(document.your_form.subcategory) {
        options.length=0;
        switch(newCat) {
EOF
foreach my $c (keys %categories) {
print <<EOF;
            case "$c":
EOF
    my $i = 0;
    foreach my $s (@{$categories{$c}}) {
        my $opts_params = ($s eq $subcategory && $c eq $category)
                ? ',true,true'
                : '';
        print <<EOF;
                options[$i]=new Option("$s" $opts_params );
EOF
        ++$i;
    }
    print <<EOF;
                break;
EOF
}
print <<EOF;
            case "Category":
                options[0]=new Option("Please choose a category");
                break;
        }
    }
}
</script>
EOF
# Well, now wasn't that fun?!

# Beginning of form
print start_form(-name=>'your_form');
print p(popup_menu(-name=>'category',
                   -values=>['Category',sort keys %categories],
                   -onChange=>
                       'catChange(this.options[this.selectedIndex].value);'),
        popup_menu(-name=>'subcategory',
                   -values=>['Please choose a category']));


##</code><code>##

  printf 'options[%d]=new Option("%s" %s );\n', $i, $s, $opts_params;