Dom Document - extract a document id & save - php

Question

I am trying to extract a specific clump of HTML using dom document.
My code is as follows:
$domd = new DOMDocument('1.0', 'utf-8');
$domd->loadHTML($string);
$this->hook = 'content';
if($this->hook !== '') {
$main = $domd->getElementById($this->hook);
$newstr = "";
foreach($main->childNodes as $node) {
$newstr .= $domd->saveXML($node, LIBXML_NOEMPTYTAG);
}
$domd->loadHTML($newstr);
}
//MORE PARSING USING THE DOMD OBJECT
It works great BUT the foreach is quite slow, and I was wondering if there's a more intelligent way of doing this. I am re-loading the HTML into the $domd so I can keep editing. In the back of my mind I feel I should be saving a fragment, not re-loading the saved $newstr into the object.
Can this be made more elegant or faster?
Thanks!

Answer 1

I'm assuming you want to mutate your existing $domd document, replacing it completely with those child nodes you're grabbing from that content node:
UPDATE: Just realized that since you were reloading using loadHTML, you probably wanted to preserve the html/body nodes that it creates. Code below has been adjusted to empty body and append the fragment there:
$domd = new DOMDocument('1.0', 'utf-8');
$domd->loadHTML($string);
$this->hook = 'content';
if($this->hook !== '') {
$main = $domd->getElementById($this->hook);
$fragment = $domd->createDocumentFragment();
while($main->hasChildNodes()) {
$fragment->appendChild($main->firstChild);
}
$body = $domd->getElementsByTagName("body")->item(0);
while($body->hasChildNodes()) {
$body->removeChild($body->firstChild);
}
$body->appendChild($fragment);
}
//MORE PARSING USING THE DOMD OBJECT