lukecav/functions.php

## functions.php
// Lazyload Converter
function add_lazyload($content) {

    $content = mb_convert_encoding($content, 'HTML-ENTITIES', "UTF-8");
    $dom = new DOMDocument();
    @$dom->loadHTML($content);

    // Convert Images
    $images = [];

    foreach ($dom->getElementsByTagName('img') as $node) {
        $images[] = $node;
    }

    foreach ($images as $node) {
        $fallback = $node->cloneNode(true);

        $oldsrc = $node->getAttribute('src');
        $node->setAttribute('data-src', $oldsrc );
        $newsrc = get_template_directory_uri() . '/images/placeholder.gif';
        $node->setAttribute('src', $newsrc);

        $oldsrcset = $node->getAttribute('srcset');
        $node->setAttribute('data-srcset', $oldsrcset );
        $newsrcset = '';
        $node->setAttribute('srcset', $newsrcset);

        $classes = $node->getAttribute('class');
        $newclasses = $classes . ' lazy lazy-hidden';
        $node->setAttribute('class', $newclasses);

        $noscript = $dom->createElement('noscript', '');
        $node->parentNode->insertBefore($noscript, $node);
        $noscript->appendChild($fallback);
    }


    // Convert Videos
    $videos = [];

    foreach ($dom->getElementsByTagName('iframe') as $node) {
        $videos[] = $node;
    }

    foreach ($videos as $node) {
        $fallback = $node->cloneNode(true);

        $oldsrc = $node->getAttribute('src');
        $node->setAttribute('data-src', $oldsrc );
        $newsrc = '';
        $node->setAttribute('src', $newsrc);

        $classes = $node->getAttribute('class');
        $newclasses = $classes . ' lazy lazy-hidden';
        $node->setAttribute('class', $newclasses);

        $noscript = $dom->createElement('noscript', '');
        $node->parentNode->insertBefore($noscript, $node);
        $noscript->appendChild($fallback);
    }

    $newHtml = preg_replace('/^<!DOCTYPE.+?>/', '', str_replace( array('<html>', '</html>', '<body>', '</body>'), array('', '', '', ''), $dom->saveHTML()));
    return $newHtml;
}
add_filter('the_content', 'add_lazyload');
add_filter('post_thumbnail_html', 'add_lazyload');
	// Lazyload Converter
	function add_lazyload($content) {

	$content = mb_convert_encoding($content, 'HTML-ENTITIES', "UTF-8");
	$dom = new DOMDocument();
	@$dom->loadHTML($content);

	// Convert Images
	$images = [];

	foreach ($dom->getElementsByTagName('img') as $node) {
	$images[] = $node;
	}

	foreach ($images as $node) {
	$fallback = $node->cloneNode(true);

	$oldsrc = $node->getAttribute('src');
	$node->setAttribute('data-src', $oldsrc );
	$newsrc = get_template_directory_uri() . '/images/placeholder.gif';
	$node->setAttribute('src', $newsrc);

	$oldsrcset = $node->getAttribute('srcset');
	$node->setAttribute('data-srcset', $oldsrcset );
	$newsrcset = '';
	$node->setAttribute('srcset', $newsrcset);

	$classes = $node->getAttribute('class');
	$newclasses = $classes . ' lazy lazy-hidden';
	$node->setAttribute('class', $newclasses);

	$noscript = $dom->createElement('noscript', '');
	$node->parentNode->insertBefore($noscript, $node);
	$noscript->appendChild($fallback);
	}


	// Convert Videos
	$videos = [];

	foreach ($dom->getElementsByTagName('iframe') as $node) {
	$videos[] = $node;
	}

	foreach ($videos as $node) {
	$fallback = $node->cloneNode(true);

	$oldsrc = $node->getAttribute('src');
	$node->setAttribute('data-src', $oldsrc );
	$newsrc = '';
	$node->setAttribute('src', $newsrc);

	$classes = $node->getAttribute('class');
	$newclasses = $classes . ' lazy lazy-hidden';
	$node->setAttribute('class', $newclasses);

	$noscript = $dom->createElement('noscript', '');
	$node->parentNode->insertBefore($noscript, $node);
	$noscript->appendChild($fallback);
	}

	$newHtml = preg_replace('/^<!DOCTYPE.+?>/', '', str_replace( array('<html>', '</html>', '<body>', '</body>'), array('', '', '', ''), $dom->saveHTML()));
	return $newHtml;
	}
	add_filter('the_content', 'add_lazyload');
	add_filter('post_thumbnail_html', 'add_lazyload');