#!/usr/bin/perl

use warnings;
use strict;
use HTML::TreeBuilder;

my $root = HTML::TreeBuilder->new_from_file(\*DATA);

my $footer = $root->look_down(
    _tag  => q{div},
    id    => q{footer},
    );

$footer->replace_with('<!-- foobar -->');

print $root->as_HTML(undef, "  ");

__DATA__
<div id="quiteok">ok</div>
<div id="footer">
 bad
 <div>
  stuff
  <div>
   and lots of it
  </div>
 </div>
</div>
<div>
 something good
</div>