add wp-rocket

wp-content/plugins/wp-rocket/inc/front/dns-prefetch.php

@@ -0,0 +1,35 @@
+<?php
+
+defined( 'ABSPATH' ) || exit;
+
+/**
+ * Adds domain names to the list of DNS Prefetch printed by wp_resource_hints
+ *
+ * @since 2.8.9
+ * @author Remy Perona
+ *
+ * @param Array  $hints URLs to print for resource hints.
+ * @param String $relation_type The relation type the URL are printed for.
+ * @return Array URLs to print
+ */
+function rocket_dns_prefetch( $hints, $relation_type ) {
+
+	// Don't add prefetch for uncached pages.
+	if ( defined( 'DONOTROCKETOPTIMIZE' ) && DONOTROCKETOPTIMIZE ) {
+		return $hints;
+	}
+
+	$domains = rocket_get_dns_prefetch_domains();
+
+	if ( (bool) $domains ) {
+		foreach ( $domains as $domain ) {
+			if ( 'dns-prefetch' === $relation_type ) {
+				$hints[] = $domain;
+			}
+		}
+	}
+
+	return $hints;
+}
+add_filter( 'wp_resource_hints', 'rocket_dns_prefetch', 10, 2 );
+