function breadcrumb_json() {
    $dom = new DOMDocument();
    $libxml_previous_state = libxml_use_internal_errors( true );

    // Populate $dom with $content, making sure to handle UTF-8.
    // Also, make sure that the doctype and HTML tags are not added to our
    // HTML fragment. http://stackoverflow.com/a/22490902/3059883
    $dom->loadHTML($html);
    // Create an instance of DOMXpath.
    $xpath = new DOMXpath( $dom );

    // Get images then loop through and add additional classes.
    $imgs = $xpath->query( "//img" );
    foreach ( $imgs as $img ) {
        $existing_class = $img->getAttribute( 'class' );
        echo $existing_class;
    }
}

add_action('wp_footer', 'breadcrumb_json');