Index: src/wp-admin/includes/admin-filters.php =================================================================== --- src/wp-admin/includes/admin-filters.php (revision 37898) +++ src/wp-admin/includes/admin-filters.php (working copy) @@ -43,6 +43,9 @@ add_action( 'admin_head', 'wp_site_icon' ); add_action( 'admin_head', '_ipad_meta' ); +// Prerendering. +add_filter( 'admin_head', 'wp_resource_hints' ); + add_action( 'admin_print_scripts-post.php', 'wp_page_reload_on_back_button_js' ); add_action( 'admin_print_scripts-post-new.php', 'wp_page_reload_on_back_button_js' ); Index: src/wp-includes/default-filters.php =================================================================== --- src/wp-includes/default-filters.php (revision 37898) +++ src/wp-includes/default-filters.php (working copy) @@ -235,6 +235,7 @@ add_action( 'wp_head', 'wp_print_head_scripts', 9 ); add_action( 'wp_head', 'wp_generator' ); add_action( 'wp_head', 'rel_canonical' ); +add_action( 'wp_head', 'wp_resource_hints' ); add_action( 'wp_head', 'wp_shortlink_wp_head', 10, 0 ); add_action( 'wp_head', 'wp_site_icon', 99 ); add_action( 'wp_footer', 'wp_print_footer_scripts', 20 ); Index: src/wp-includes/general-template.php =================================================================== --- src/wp-includes/general-template.php (revision 37898) +++ src/wp-includes/general-template.php (working copy) @@ -2788,6 +2788,96 @@ } /** + * Prints resource hints to browsers for pre-fetching, pre-rendering and pre-connecting to web sites. + * + * Gives hints to browsers to prefetch specific pages or render them in the background, + * to perform DNS lookups or to begin the connection handshake (DNS, TCP, TLS) in the background. + * + * These performance improving indicators work by using ``. + * + * @since 4.6.0 + */ +function wp_resource_hints() { + $hints = array( + 'preconnect' => array( 's.w.org' ), + 'prerender' => array(), + 'prefetch' => array(), + 'dns-prefetch' => wp_resource_hints_scripts_styles(), + ); + + if ( is_admin() ) { + $screen = get_current_screen(); + + if ( 'edit-post' === $screen->id ) { + $hints['prefetch'][] = admin_url( 'css/edit.css' ); + $hints['prefetch'][] = includes_url( 'js/tinymce/tinymce.min.js' ); + } else if ( 'users' === $screen->id ) { + $hints['prefetch'][] = admin_url( 'js/user-profile.js' ); + } + } + + foreach ( $hints as $method => $urls ) { + /** + * Filters domains and URLs for resource hints. + * + * @since 4.6.0 + * + * @param array $urls URLs to print for resource hints. + * @param string $method The method the URLs are printed for, e.g. 'preconnect' or 'prerender'. + */ + $urls = array_unique( apply_filters( 'wp_resource_hints', $urls, $method ) ); + + foreach ( $urls as $url ) { + $url = esc_url( $url, array( 'http', 'https' ) ); + + + if ( in_array( $method, array( 'preconnect', 'dns-prefetch' ) ) ) { + $parsed = parse_url( $url ); + + if ( ! empty( $parsed['scheme'] ) ) { + $url = $parsed['scheme'] . '://' . $parsed['host']; + } else { + $url = $parsed['host']; + } + } + + printf( "\r\n", $method, $url ); + } + } +} + +/** + * Adds dns-prefetch for all scripts and styles enqueued from external hosts. + * + * @since 4.6.0 + */ +function wp_resource_hints_scripts_styles() { + global $wp_scripts, $wp_styles; + + $unique_hosts = array(); + + if ( is_object( $wp_scripts ) && ! empty( $wp_scripts->registered ) ) { + foreach ( $wp_scripts->registered as $registered_script ) { + $this_host = parse_url( $registered_script->src, PHP_URL_HOST ); + if ( ! in_array( $this_host, $unique_hosts ) && ! empty( $this_host ) && $this_host !== $_SERVER['SERVER_NAME'] ) { + $unique_hosts[] = $this_host; + } + } + } + + if ( is_object( $wp_styles ) && ! empty( $wp_styles->registered ) ) { + foreach ( $wp_styles->registered as $registered_style ) { + $this_host = parse_url( $registered_style->src, PHP_URL_HOST ); + if ( ! in_array( $this_host, $unique_hosts ) && ! empty( $this_host ) && $this_host !== $_SERVER['SERVER_NAME'] ) { + $unique_hosts[] = $this_host; + } + } + } + + return $unique_hosts; +} + +/** * Whether the user should have a WYSIWIG editor. * * Checks that the user requires a WYSIWIG editor and that the editor is Index: tests/phpunit/tests/general/resourceHints.php =================================================================== --- tests/phpunit/tests/general/resourceHints.php (revision 0) +++ tests/phpunit/tests/general/resourceHints.php (working copy) @@ -0,0 +1,163 @@ +old_wp_scripts = isset( $GLOBALS['wp_scripts'] ) ? $GLOBALS['wp_scripts'] : null; + remove_action( 'wp_default_scripts', 'wp_default_scripts' ); + $GLOBALS['wp_scripts'] = new WP_Scripts(); + $GLOBALS['wp_scripts']->default_version = get_bloginfo( 'version' ); + } + + function tearDown() { + $GLOBALS['wp_scripts'] = $this->old_wp_scripts; + add_action( 'wp_default_scripts', 'wp_default_scripts' ); + parent::tearDown(); + } + + function test_should_have_defaults_on_frontend() { + $expected = "\r\n"; + + $this->expectOutputString( $expected ); + + wp_resource_hints(); + } + + function test_edit_post_screen() { + $expected = "\r\n" . + "\r\n" . + "\r\n"; + + set_current_screen( 'edit.php' ); + + $actual = get_echo( 'wp_resource_hints' ); + + set_current_screen( 'front' ); + + $this->assertEquals( $expected, $actual ); + } + + function test_users_screen() { + $expected = "\r\n" . + "\r\n"; + + set_current_screen( 'users.php' ); + + $actual = get_echo( 'wp_resource_hints' ); + + set_current_screen( 'front' ); + + $this->assertEquals( $expected, $actual ); + } + + function test_dns_prefetching() { + $expected = "\r\n" . + "\r\n" . + "\r\n" . + "\r\n"; + + add_filter( 'wp_resource_hints', array( $this, '_add_dns_prefetch_domains' ), 10, 2 ); + + $actual = get_echo( 'wp_resource_hints' ); + + remove_filter( 'wp_resource_hints', array( $this, '_add_dns_prefetch_domains' ) ); + + $this->assertEquals( $expected, $actual ); + } + + function _add_dns_prefetch_domains( $hints, $method ) { + if ( 'dns-prefetch' === $method ) { + $hints[] = 'http://wordpress.org'; + $hints[] = 'https://google.com'; + $hints[] = '//make.wordpress.org'; + } + + return $hints; + } + + function test_prerender() { + $expected = "\r\n" . + "\r\n" . + "\r\n" . + "\r\n"; + + add_filter( 'wp_resource_hints', array( $this, '_add_prerender_urls' ), 10, 2 ); + + $actual = get_echo( 'wp_resource_hints' ); + + remove_filter( 'wp_resource_hints', array( $this, '_add_prerender_urls' ) ); + + $this->assertEquals( $expected, $actual ); + } + + function _add_prerender_urls( $hints, $method ) { + if ( 'prerender' === $method ) { + $hints[] = 'https://make.wordpress.org/great-again'; + $hints[] = 'http://jobs.wordpress.net'; + $hints[] = '//core.trac.wordpress.org'; + } + + return $hints; + } + + function test_parse_url_dns_prefetch() { + $expected = "\r\n" . + "\r\n"; + + add_filter( 'wp_resource_hints', array( $this, '_add_dns_prefetch_long_urls' ), 10, 2 ); + + $actual = get_echo( 'wp_resource_hints' ); + + remove_filter( 'wp_resource_hints', array( $this, '_add_dns_prefetch_long_urls' ) ); + + $this->assertEquals( $expected, $actual ); + } + + function _add_dns_prefetch_long_urls( $hints, $method ) { + if ( 'dns-prefetch' === $method ) { + $hints[] = 'http://make.wordpress.org/wp-includes/css/editor.css'; + } + + return $hints; + } + + function test_dns_prefetch_styles() { + $expected = "\r\n" . + "\r\n"; + + $args = array( + 'family' => 'Open+Sans:400', + 'subset' => 'latin', + ); + + wp_enqueue_style( 'googlefonts', add_query_arg( $args, "//fonts.googleapis.com/css" ) ); + + $actual = get_echo( 'wp_resource_hints' ); + + $this->assertEquals( $expected, $actual ); + + } + + function test_dns_prefetch_scripts() { + $expected = "\r\n" . + "\r\n"; + + $args = array( + 'family' => 'Open+Sans:400', + 'subset' => 'latin', + ); + + wp_enqueue_script( 'googlefonts', add_query_arg( $args, "//fonts.googleapis.com/css" ) ); + + $actual = get_echo( 'wp_resource_hints' ); + + $this->assertEquals( $expected, $actual ); + } + +}