use HTML::TreeBuilder;

my $tree = HTML::TreeBuilder->new();
$tree->parse($html);
$tree->eof();

my %words = ();
foreach my $word ($tree->as_text() =~ m/(\b\w+\'?\w+)/g) {
        $words{$word} += 1;
}

my @word_pos;
my $key;

foreach $key (keys %words) {
        pos($html) = 0;
        while ($html =~ />[^<]*?(\b$key\b).*?[<\$]/gis) {
                push @word_pos, [$key, $-[1]];
        }
}