Simple DomDocument and GetElementsByTagName [duplicate] - php

Question

This question already has answers here:
How i can get td nodeValue with specific class?
(2 answers)
Closed 2 years ago.
I'm trying to parse a webpage for the ISBN number, the HTML looks like:
<tr>
<td>ISBN: </td>
<td itemprop="isbn">9781472223821</td>
</tr>
I currently have:
header('Content-Type:application/json');
$url = "URL Removed";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
$res = curl_exec($ch);
curl_close($ch);
$dom = new DomDocument();
#$dom->loadHTML($res);
$searchNodes = $dom->getElementsByTagName("//td[#itemprop='isbn']");
foreach ($searchNodes as $node) {
echo $node->nodeValue, PHP_EOL;
}
When i run this i get no output, i've double checked the xpath query in the chrome dev tools and that correctly selects the element i'm after. i believe its something to do with teh nodeValue option. I've tried a var_dump on the $searchNode variable and get
object(DOMNodeList)#2 (1) {
["length"]=>
int(0)
}
Is anyone able to highlight my next steps to investigate with this.

Answer 1

getElementsByTagName expects only a single tag name. Here is a working example using DOMXPath:
$res = '
<tr>
<td>ISBN: </td>
<td itemprop="isbn">9781472223821</td>
</tr>
';
$dom = new DomDocument();
$dom->loadHTML($res);
$xpath = new DOMXPath($dom);
$searchNodes = $xpath->query("//td[#itemprop='isbn']");
foreach ($searchNodes as $node) {
echo $node->nodeValue, PHP_EOL;
}