DOMDocument replace occurrence of text in nodeValue with <a> link

function replace_text_with_anchor($domDocument, $searchFor, $replaceWith, $url) {
  $query = "//text()[contains(., '" . $searchFor . "')]";
  $xpath = new DOMXPath($domDocument);
  $textNodes = $xpath->query($query);
  foreach ($textNodes as $node) {
    $fragment = $domDocument->createDocumentFragment();
    $fragment->appendXML("<a href=\"" . $url . "\">" . $replaceWith . "</a>");
    $node->parentNode->replaceChild($fragment, $node);
  }
}