Index: src/wp-admin/includes/admin-filters.php =================================================================== --- src/wp-admin/includes/admin-filters.php (revision 37473) +++ 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_browser_hints' ); + add_action( 'post_edit_form_tag', 'post_form_autocomplete_off' ); add_action( 'update_option_home', 'update_home_siteurl', 10, 2 ); Index: src/wp-includes/default-filters.php =================================================================== --- src/wp-includes/default-filters.php (revision 37473) +++ 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_browser_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 37473) +++ src/wp-includes/general-template.php (working copy) @@ -2755,6 +2755,172 @@ } /** + * Makes sure browser hint array has unique values. + * + * @since 4.6.0 + * + * @param array $urls Array of browser hints. + */ +function unique_browser_hints( $urls ) { + $seen = array(); + foreach( $urls as $url ) { + if ( ! in_array( $url, $seen ) ) { + array_push( $seen, $url ); + } + } + return $seen; +} + +/** + * Prints out brower hints for dns-prefetch, prerender, preconnect, etc. + * + * @since 4.6.0 + */ +function wp_browser_hints() { + + $default_urls = array( + array( 'preconnect', 's.w.org' ), + ); + + /** + * Filters domains and urls for browser hints. + * + * @since 4.6.0 + * + * @param array $urls URL's to print for browser hints. + */ + $urls = apply_filters( 'browser_hints', $default_urls ); + $prerender_urls = wp_prerender_posts(); + $enqueued_hosts = wp_hint_scripts_styles(); + $urls = array_merge( $urls, $prerender_urls, $enqueued_hosts ); + + if ( is_admin() ) { + $admin_urls = prerender_admin_urls(); + $urls = array_merge( $urls, $admin_urls ); + } + + $urls = unique_browser_hints( $urls ); + + foreach ( $urls as $url ) { + if ( $url[0] === 'prerender' ) { + $url[1] = esc_url( $url[1], array( 'http', 'https' ) ); + } elseif ( $url[0] === 'dns-prefetch' || $url[0] === 'preconnect' ) { + $url[1] = esc_url( untrailingslashit( $url[1] ), array( 'http', 'https' ) ); + } + printf( "\r\n", $url[0], $url[1] ); + } +} + +/** + * Adds posts to be prerendered. + * + * @since 4.6.0 + */ +function wp_prerender_posts() { + /** + * Filters the number of posts to prerender. + * + * @since 4.6.0 + * + * @param int $prerender_count Number of posts to prerender. + */ + $num_posts = apply_filters( 'prerender_count', 1 ); + + $posts_to_prerender = array(); + + if ( is_home() ) { + + $count = 1; + while( have_posts() && $count <= $num_posts ) { + the_post(); + array_push( $posts_to_prerender, array( 'prerender', get_the_permalink() ) ); + $count++; + } + + rewind_posts(); + + } elseif ( is_single() ) { + + $next_post = get_next_post(); + $previous_post = get_previous_post(); + + if ( ! empty( $next_post ) ) { + array_push( $posts_to_prerender, array( 'prerender', get_permalink( $next_post->ID ) ) ); + } + + if ( ! empty( $previous_post ) ) { + array_push( $posts_to_prerender, array( 'prerender', get_permalink( $previous_post->ID ) ) ); + } + + } + + return $posts_to_prerender; +} + +/** + * Prerender pages in the admin that users are most likely to visit. + * + * @since 4.6.0 + */ +function prerender_admin_urls() { + + $default_urls = array( + array( 'prerender', admin_url( 'post-new.php' ) ), + ); + + /** + * Filters which admin pages will be prerendered. + * + * @since 4.6.0 + * + * @param array $urls Admin URL's to prerender. + */ + $urls = apply_filters( 'prerender_admin_pages', $default_urls ); + + return $urls; +} + +/** + * Adds dns-prefetch for all scripts and styles enqueued from external hosts. + * + * @since 4.6.0 + */ +function wp_hint_scripts_styles() { + global $wp_scripts, $wp_styles; + + $unique_hosts = array(); + + 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; + } + } + + 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; + } + } + + $unique_hosts = array_map( 'add_prefetch_attr', $unique_hosts ); + return $unique_hosts; +} + +/** + * Adds dns-prefetch to hosts of scripts and styles. + * + * @since 4.6.0 + * + * @param array $hosts A hostname. + */ +function add_prefetch_attr( $host ) { + $host = array( 'dns-prefetch', $host ); + return $host; +} + +/** * 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/template.php =================================================================== --- tests/phpunit/tests/general/template.php (revision 37473) +++ tests/phpunit/tests/general/template.php (working copy) @@ -345,4 +345,50 @@ $this->custom_logo_id = $this->_make_attachment( $upload ); return $this->custom_logo_id; } + + /** + * @ticket 34292 + */ + function test_wp_dns_prefetch() { + $this->assertEmpty( get_echo( 'wp_dns_prefetch' ) ); + + add_filter( 'dns_prefetch_domains', array( $this, '_add_dns_prefetch_domains' ) ); + + $expected = "\r\n" . + "\r\n" . + "\r\n"; + + $this->assertEquals( $expected, get_echo( 'wp_dns_prefetch' ) ); + } + + function _add_dns_prefetch_domains( $domains ) { + $domains[] = 'http://wordpress.org'; + $domains[] = 'https://google.com'; + $domains[] = '//make.wordpress.org'; + + return $domains; + } + + /** + * @ticket 34292 + */ + function test_wp_prerender() { + $this->assertEmpty( get_echo( 'wp_prerender' ) ); + + add_filter( 'prerender_urls', array( $this, '_add_prerender_urls' ) ); + + $expected = "\r\n" . + "\r\n" . + "\r\n"; + + $this->assertEquals( $expected, get_echo( 'wp_prerender' ) ); + } + + function _add_prerender_urls( $urls ) { + $urls[] = 'https://make.wordpress.org/great-again'; + $urls[] = 'http://jobs.wordpress.net'; + $urls[] = '//core.trac.wordpress.org'; + + return $urls; + } }