PHP | DOMDocument getElementById() Function

<?php

// Create a new DOM Document
$dom = new DOMDocument('1.0', 'iso-8859-1');

// Enable validate on parse
$dom->validateOnParse = true;

// Create a div element
$element = $dom->appendChild(new DOMElement('div'));

// Create a id attribute to div
$attr = $element->setAttributeNode(
        new DOMAttr('id', 'my_id'));

// Set that attribute as id
$element->setIDAttribute('id', true);

// Get the tag name
$tagname = $dom->getElementById('my_id')->tagName;

echo $tagname;
?>

<?php

// Create a new DOM Document
$dom = new DOMDocument('1.0', 'iso-8859-1');

// Enable validate on parse
$dom->validateOnParse = true;

// Create a div element
$element = $dom->appendChild(new DOMElement('div',
   'Hey, this is the text content of the div element.'));

// Create a id attribute to div
$attr = $element->setAttributeNode(
          new DOMAttr('id', 'my_id'));

// Set that attribute as id
$element->setIDAttribute('id', true);

// Get the tag content
$tagcontent = $dom->getElementById('my_id')->textContent;

echo $tagcontent;
?>