How to extract html comments and all html contained by node?

Question

I'm creating a little web app to help me manage and analyze the content of my websites, and cURL is my favorite new toy. I've figured out how to extract info about all sorts of elements, how to find all elements with a certain class, etc., but I am stuck on two problems (see below). I hope there is some nifty xpath answer, but if I have to resort to regular expressions I guess that's ok. Although I'm not so great with regex so if you think that's the way to go, I'd appreciate examples...

Pretty standard starting point:

$ch = curl_init();
 curl_setopt($ch, CURLOPT_USERAGENT, $userAgent);
 curl_setopt($ch, CURLOPT_URL,$target_url);
 curl_setopt($ch, CURLOPT_FAILONERROR, true);
 curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
 curl_setopt($ch, CURLOPT_AUTOREFERER, true);
 curl_setopt($ch, CURLOPT_RETURNTRANSFER,true);
 curl_setopt($ch, CURLOPT_TIMEOUT, 10);
 $html = curl_exec($ch);
 if (!$html) {
 $info .= "<br />cURL error number:" .curl_errno($ch);
 $info .= "<br />cURL error:" . curl_error($ch);
 return $info;
 }
 $dom = new DOMDocument();
 @$dom->loadHTML($html);
 $xpath = new DOMXPath($dom);

and extraction of info, for example:

// iframes
 $iframes = $xpath->evaluate("/html/body//iframe");
 $info .= '<h3>iframes ('.$iframes->length.'):</h3>';
 for ($i = 0; $i < $iframes->length; $i++) {
 // get iframe attributes
 $iframe = $iframes->item($i);
 $framesrc = $iframe->getAttribute("src");
 $framewidth = $iframe->getAttribute("width");
 $frameheight = $iframe->getAttribute("height");
 $framealt = $iframe->getAttribute("alt");
 $frameclass = $iframe->getAttribute("class");
 $info .= $framesrc.'&nbsp;('.$framewidth.'x'.$frameheight.'; class="'.$frameclass.'")'.'<br />';
 }

Questions/Problems:

1. How to extract HTML comments?

   I can't figure out how to identify the comments – are they considered nodes, or something else entirely?

2. How to get the entire content of a div, including child nodes? So if the div contains an image and a couple of hrefs, it would find those and hand it all back to me as a block of HTML.

• Marcel Korpel: Don't use RegEx for extracting pieces of HTML markup, see RegEx match open tags except XHTML self-contained tags

Answer 1

Comment nodes should be easy to find in XPath with the comment() test, analogous to the text() test:

$comments = $xpath->query('//comment()'); // or another path, as you prefer

They are standard nodes: here is the manual entry for the DOMComment class.

---

To your other question, it's a bit trickier. The simplest way is to use saveXML() with its optional $node argument:

$html = $dom->saveXML($el); // $el should be the element you want to get 
 // the HTML for

• codebird: Hooray! Thank you so much. Problems solved. By the way, if you don't mind, in this context what's the difference between $xpath->query an $xpath->evaluate?
• lonesomeday: @alison Glad to help. Here there is no difference.

Answer 2

For the HTML comments a fast method is:

 function getComments ($html) {
 $rcomments = array();
 $comments = array();
 if (preg_match_all('#<\!--(.*?)-->#is', $html, $rcomments)) {
 foreach ($rcomments as $c) {
 $comments[] = $c[1];
 }
 return $comments;
 } else {
 // No comments matchs
 return null;
 }
 }

Answer 3

That Regex \s*<!--[\s\S]+?-->
Helps to you.

In regex Test

Answer 4

for comments your looking for recursive regex. For instance, to get rid of html comments:

preg_replace('/<!--(?(?=<!--)(?R)|.)*?-->/s',$yourHTML);

to find them:

preg_match_all('/(<!--(?(?=<!--)(?R)|.)*?-->)/s',$yourHTML,$comments);

• Resheil Agarwal: This doesn't work. I tried it.