My first posted code snippet. Sorry if I leave anythign out, include anything extraneous, etc.

This snippet will generate the Javascript for 2 popup menus, the 2nd of which has varying options depending on the value of the first. The form in this example is named 'your_form', the first popup_menu is named 'category' and the second is named 'subcategory'. The %categories hash should have keys thats are the categories and values that are arrays of subcategories.

I tried to make it as neat as possible. It was formatted in an editor with an 80-character width.

UPDATE: Made some changes suggested by davidrw

# Sample categories hash, courtesy of davidrw
my %categories = ( A => [ 'B', 'Z' ], C => ['D', 'E'] );

my $category = param('category') || '';
my $subcategory = param('subcategory') || '';

# Generate javascript
print <<EOF;
<script language="javascript">
    function catChange(newCat) {
        with(document.your_form.subcategory) {
            options.length=0;
            switch(newCat) {
EOF
foreach $c (keys %categories) {
    print <<EOF;
            case "$c":
EOF
    my $i = 0;
    foreach my $s (@{$categories{$c}}) {
        # Keeps menu options when page reloads
        # Only matters when form target is the script itself
        my $opts_params = ($s eq $subcategory && $c eq $category)
                ? ',true,true'
                : '';
        print <<EOF;
                options[$i]=new Option("$s" $opts_params);
EOF
        ++$i;
    }
    print "break;\n";
}
    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].val
+ue);'),
        popup_menu(-name=>'subcategory',
                   -values=>['Please choose a category']));

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In reply to Double popup_menu by wink

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