use HTML::Parser;

    use Symbol;
    my $TXT = gensym;

    my $parser = HTML::Parser->new(api_version => 3,
        text_h => [ sub {
            print $TXT @_;
        }, "dtext" ]);

    for my $html (@ARGV) {
        (my $txt = $html) =~ s/\.html$/\.txt/;
        open $TXT, ">$txt" or die "Can't open $txt: $!";
        $parser->parse_file($html);
        close $TXT or die "Can't close $txt: $!";
    }

##</code><code>##

    % ./foo.pl file1.html file2.html ...