Online PHP editor | output for seaMg

<?php $html = <<<HTML <p>Some random text <iframe src="http://some-random-link.com" width="425" height="350" frameborder="0"></iframe> <iframe src="https://cant-touch-this.com" width="425" height="350" frameborder="0"></iframe> </p> HTML; $dom = new DOMDocument; $dom->loadHTML($html, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD); $xpath = new DOMXPath($dom); foreach ($xpath->query("//iframe[starts-with(@src, 'http') and not(starts-with(@src, 'https'))]/@src") as $src) { $src->nodeValue = substr_replace($src->nodeValue, 's', 4, 0); } echo $dom->saveHTML();