(PHP 5)
DOMDocument::getElementById — Searches for an element with a certain id
This function is similar to DOMDocument::getElementsByTagName but searches for an element with a given id.
For this function to work, you will need either to set some ID attributes with DOMElement::setIdAttribute or a DTD which defines an attribute to be of type ID. In the later case, you will need to validate your document with DOMDocument::validate or DOMDocument->validateOnParse before using this function.
The unique id value for an element.
Returns the DOMElement or NULL if the element is not found.
Example #1 DOMDocument->getElementById() Example
<?php
$doc = new DomDocument;
// We need to validate our document before refering to the id
$doc->validateOnParse = true;
$doc->Load('book.xml');
echo "The element whose id is books is: " . $doc->getElementById('books')->tagName . "\n";
?>
上例将输出：
The element whose id is books is: chapter