find if post name appears in any keyword from html string

<?php
  function has_post_name($post_name, $html_string) {
    $dom = new DOMDocument;
    $dom->loadHTML($html_string);
    $xpath = new DOMXpath($dom);
    $items = $xpath->query("//*[contains(@class,'widget')]//*[contains(@class,'keyword')]");
    foreach ($items as $n) {
      $text = trim($n->nodeValue);
      if (strcasecmp($text, $post_name) == 0) {
        return true;
      }
    }
    return false;
  }
?>