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<?php |
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/** |
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* Metasync_JS_Minifier |
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* Conservative regex-based JS minification engine (no AST parsing). |
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* Hooks into script_loader_tag to rewrite enqueued scripts to cached minified versions. |
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* |
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* @package Search Atlas SEO |
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* @copyright Copyright (C) 2021-2025, Search Atlas Group - support@searchatlas.com |
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* @since 2.5.23 |
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*/ |
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|
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if (!defined('ABSPATH')) { |
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exit; |
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} |
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|
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class Metasync_JS_Minifier { |
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|
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/** @var array */ |
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private $settings; |
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|
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/** @var array Handles to exclude from minification. */ |
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private $excluded_handles = []; |
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|
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public function __construct(array $settings) { |
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$this->settings = $settings; |
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$this->excluded_handles = array_filter( |
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array_map('trim', explode(',', $settings['js_exclude_handles'] ?? '')) |
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); |
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|
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add_filter('script_loader_tag', [$this, 'maybe_minify_script'], 998, 3); |
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} |
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|
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/** |
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* Filter: attempt to minify the script and rewrite the tag to use the cached version. |
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* |
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* @param string $tag The full <script> tag HTML. |
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* @param string $handle The script's registered handle. |
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* @param string $src The script's source URL. |
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* @return string Modified or original tag. |
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*/ |
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public function maybe_minify_script(string $tag, string $handle, string $src): string { |
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// Skip admin, login, excluded handles, inline scripts |
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if (is_admin() || $this->is_excluded($handle) || $this->is_login_page() || empty($src)) { |
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return $tag; |
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} |
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|
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// Only process local files |
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$local_path = $this->url_to_local_path($src); |
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if (!$local_path || !file_exists($local_path)) { |
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return $tag; |
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} |
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|
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// Skip already-minified files |
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if (preg_match('/\.min\.js$/i', $local_path)) { |
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return $tag; |
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} |
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|
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// Skip ES module files — relocating them breaks relative import paths |
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if ($this->is_es_module($tag, $local_path)) { |
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return $tag; |
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} |
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|
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// Check cache |
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$cached = Metasync_Minification_Cache::get_cached_file($handle, 'js', $local_path); |
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if ($cached) { |
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return str_replace($src, $cached['url'], $tag); |
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} |
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|
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// Read and minify |
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// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents |
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$content = file_get_contents($local_path); |
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if ($content === false || strlen($content) === 0) { |
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return $tag; |
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} |
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|
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$minified = self::minify($content); |
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|
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// Store in cache |
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$cached = Metasync_Minification_Cache::store_cached_file($handle, 'js', $local_path, $minified); |
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if ($cached) { |
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return str_replace($src, $cached['url'], $tag); |
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} |
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|
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return $tag; |
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} |
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|
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/** |
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* Minify a JavaScript string using conservative regex-based transformations. |
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* |
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* @param string $js Raw JavaScript content. |
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* @return string Minified JavaScript. |
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*/ |
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public static function minify(string $js): string { |
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// 1. Remove multi-line comments (but preserve conditional compilation comments /*! ... */) |
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$js = preg_replace('/\/\*(?!![\s\S]*?\*\/)[\s\S]*?\*\//', '', $js); |
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|
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// 2. Remove single-line comments (careful with URLs and regex literals) |
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// Only remove // comments that are not inside strings or URLs |
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$js = preg_replace('/(?<![:\"\'\\\])\/\/[^\n]*/', '', $js); |
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|
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// 3. Remove trailing whitespace per line |
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$js = preg_replace('/[ \t]+$/m', '', $js); |
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|
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// 4. Collapse multiple blank lines into one |
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$js = preg_replace('/\n{3,}/', "\n\n", $js); |
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|
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// 5. Remove leading whitespace on lines (conservative: only spaces/tabs at start of line) |
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$js = preg_replace('/^\s+/m', '', $js); |
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|
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// 6. Collapse multiple spaces into one (within lines) |
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$js = preg_replace('/[ \t]+/', ' ', $js); |
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|
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// 7. Remove spaces around operators (conservative set only) |
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$js = preg_replace('/\s*([{};,])\s*/', '$1', $js); |
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|
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// 8. Remove empty lines |
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$js = preg_replace('/^\s*$/m', '', $js); |
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$js = preg_replace('/\n+/', "\n", $js); |
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|
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return trim($js); |
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} |
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|
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/** |
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* Check if a script is an ES module (uses import/export with relative paths). |
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* Relocating ES modules to the cache directory breaks their relative imports. |
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*/ |
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private function is_es_module(string $tag, string $local_path): bool { |
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// Check if the script tag has type="module" |
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if (preg_match('/type\s*=\s*["\']module["\']/', $tag)) { |
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return true; |
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} |
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|
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// Read beginning of file to check for ES module import/export syntax |
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// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents |
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$head = file_get_contents($local_path, false, null, 0, 2048); |
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if ($head === false) { |
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return false; |
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} |
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|
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// Detect relative import paths like: from"./js/..." or from'../something' |
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if (preg_match('/\bimport\b.+?\bfrom\s*["\']\.\.?\//', $head)) { |
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return true; |
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} |
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|
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return false; |
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} |
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|
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/** |
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* Check if a handle is excluded. |
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*/ |
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private function is_excluded(string $handle): bool { |
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return in_array($handle, $this->excluded_handles, true); |
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} |
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|
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/** |
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* Convert a URL to a local filesystem path. |
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* |
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* @param string $url The script URL. |
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* @return string|false Local path or false if not local. |
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*/ |
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private function url_to_local_path(string $url) { |
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$url = strtok($url, '?'); |
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|
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if (strpos($url, '//') === 0) { |
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$url = 'https:' . $url; |
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} |
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|
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$site_url = site_url(); |
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$content_url = content_url(); |
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$abspath = ABSPATH; |
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|
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if (strpos($url, $site_url) === 0) { |
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$relative = str_replace($site_url, '', $url); |
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return $abspath . ltrim($relative, '/'); |
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} |
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|
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if (strpos($url, $content_url) === 0) { |
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$relative = str_replace($content_url, '', $url); |
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return WP_CONTENT_DIR . '/' . ltrim($relative, '/'); |
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} |
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|
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if (strpos($url, '/wp-content/') === 0 || strpos($url, '/wp-includes/') === 0) { |
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return $abspath . ltrim($url, '/'); |
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} |
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|
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return false; |
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} |
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|
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/** |
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* Check if current request is the login page. |
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*/ |
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private function is_login_page(): bool { |
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return in_array($GLOBALS['pagenow'] ?? '', ['wp-login.php', 'wp-register.php'], true); |
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} |
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} |
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|
