Online PHP editor | output for TTRmF

<?php $content = <<<DATA <body> <div class="entry-content"> <p><img src="https://picsum.photos/200/300" alt="" width="3264" height="2448" class="alignleft size-full wp-image-24" srcset="http://localhost/wp/wp-content/uploads/2018/08/image-1356510220.jpg 3264w, http://localhost/wp/wp-content/uploads/2018/08/image-1356510220-300x225.jpg 300w, http://localhost/wp/wp-content/uploads/2018/08/image-1356510220-768x576.jpg 768w, http://localhost/wp/wp-content/uploads/2018/08/image-1356510220-1024x768.jpg 1024w" sizes="(max-width: 767px) 89vw, (max-width: 1000px) 54vw, (max-width: 1071px) 543px, 580px" /></p> <p>Lorem ipsum dolor sit amet Lorem ipsum dolor sit amet Lorem ipsum dolor sit amet</p> <p><img src="https://picsum.photos/200/300" alt="" width="3264" height="2448" class="alignleft size-full wp-image-24" srcset="http://localhost/wp/wp-content/uploads/2018/08/image-1356510220.jpg 3264w, http://localhost/wp/wp-content/uploads/2018/08/image-1356510220-300x225.jpg 300w, http://localhost/wp/wp-content/uploads/2018/08/image-1356510220-768x576.jpg 768w, http://localhost/wp/wp-content/uploads/2018/08/image-1356510220-1024x768.jpg 1024w" sizes="(max-width: 767px) 89vw, (max-width: 1000px) 54vw, (max-width: 1071px) 543px, 580px" /></p> </div> </body> DATA; libxml_use_internal_errors(true); $dom = new DOMDocument('1.0', 'UTF-8'); $dom->loadHTML($content, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD); $keyword = "HELLO"; $images = $dom->getElementsByTagName('img'); foreach ( $images as $image) { if (empty($image->getAttribute("alt"))) { $image->setAttribute('alt', $keyword); } } $content = $dom->saveHTML(); echo $content;