使用getAttribute（）时DOMDocument返回500

I have an html iframe code and I want to get the href value of the first a tag. I have this php code

<?php
$iframe_input=$_GET["code"];
$doc_url = new DOMDocument();
@$doc_url->loadHTML($iframe_input);

$iframe_links = $doc_url->getElementsByTagName('a');
$iframe_link = $iframe_links[0]->getAttribute('href');

echo $iframe_link;
?>

When I run it locally on xampp everything is ok. But when I run it on a nginx webserver (digitalocean), I get an HTTP 500.

PHP message: PHP Fatal error: Cannot use object of type DOMNodeList as array

FYI If I remove$iframe_link = $iframe_links[0]->getAttribute('href');, it doesn't return an error.

If you receive that error it's because on your server you have an older version of PHP.

You can use DOMNodeList as array only from version 5.6 . Check here

If you want to work on your server that have an older version you need to get the item from element 0 using the method item() like this:

$iframe_links->item(0)->getAttribute('href');