(PHP 8 >= 8.4.0)
DOMNode::compareDocumentPosition — 比較兩個節點的位置
`other`要比較位置的節點，相對於此節點。
**`DOMNode::DOCUMENT_POSITION_*`** 常數的位元遮罩 (bitmask)。
範例 #1 `DOMNode::compareDocumentPosition()` 範例
<?php
$xml = <<<XML
<root>
<child1/>
<child2/>
</root>
XML;
$dom = new DOMDocument();
$dom->loadXML($xml);
$root = $dom->documentElement;
$child1 = $root->firstElementChild;
$child2 = $child1->nextElementSibling;
var_dump($root->compareDocumentPosition($child1));
var_dump($child2->compareDocumentPosition($child1));
?>上述範例將輸出：
int(20) // This is DOMNode::DOCUMENT_POSITION_CONTAINED_BY | DOMNode::DOCUMENT_POSITION_FOLLOWING int(2) // This is DOMNode::DOCUMENT_POSITION_PRECEDING