How can I remove an entire HTML tag (and its contents) by its class using a regex?

Question

I am not very good with Regex but I am learning.

I would like to remove some html tag by the class name. This is what I have so far :

<div class="footer".*?>(.*?)</div>

The first .*? is because it might contain other attribute and the second is it might contain other html stuff.

What am I doing wrong? I have try a lot of set without success.

Update

Inside the DIV it can contain multiple line and I am playing with Perl regex.

Answer 1

As other people said, HTML is notoriously tricky to deal with using regexes, and a DOM approach might be better. E.g.:

use HTML::TreeBuilder::XPath;

my $tree = HTML::TreeBuilder::XPath->new;
$tree->parse_file( 'yourdocument.html' );

for my $node ( $tree->findnodes( '//*[@class="footer"]' ) ) {
    $node->replace_with_content;   # delete element, but not the children
}

print $tree->as_HTML;

Answer 2

You will also want to allow for other things before class in the div tag

<div[^>]*class="footer"[^>]*>(.*?)</div>

Also, go case-insensitive. You may need to escape things like the quotes, or the slash in the closing tag. What context are you doing this in?

Also note that HTML parsing with regular expressions can be very nasty, depending on the input. A good point is brought up in an answer below - suppose you have a structure like:

<div>
    <div class="footer">
        <div>Hi!</div>
    </div>
</div>

Trying to build a regex for that is a recipe for disaster. Your best bet is to load the document into a DOM, and perform manipulations on that.

Pseudocode that should map closely to XML::DOM:

document = //load document
divs = document.getElementsByTagName("div");
for(div in divs) {
    if(div.getAttributes["class"] == "footer") {
        parent = div.getParent();
        for(child in div.getChildren()) {
            // filter attribute types?
            parent.insertBefore(div, child);
        }
        parent.removeChild(div);
    }
}

---

Here is a perl library, HTML::DOM, and another, XML::DOM
.NET has built-in libraries to handle dom parsing.