combine_js2.php

<? 
define('FILE_TYPE', 'text/javascript');
define('CACHE_LENGTH', 31356000); // length of time to cache output file, default approx 1 year
define('CREATE_ARCHIVE', true); // set to false to suppress writing of code archive, files will be merged on each request
define('ARCHIVE_FOLDER', 'beta/js/archive'); // location to store archive, don't add starting or trailing slashes

$aFiles = array(
      'js/jquery/jquery-1.3.2.min.js',
      'js/jquery/jquery.autogrow.js',
      'js/jquery/thickbox/thickbox.js',
      'js/jquery/jquery.corner.js',
      'js/jquery/ac/jquery.autocomplete.js',
      'js/jquery/ac/jquery.bgiframe.min.js',
      'js/jquery/jquery.emptyonclick.js',      
      'js/jquery/alerts/jquery.alerts.js',
      'js/jquery/alerts/jquery.ui.draggable.js',
      'js/date.js',
      'pager/jquery.tablesorter.js',
      'pager/jquery.tablesorter.pager.js',
      'pager/docs.js',
      'pager/chili-1.8b.js',
   );

$sDocRoot = $_SERVER['DOCUMENT_ROOT'];
if (isset($_GET['version'])) {
      $iETag = (int)$_GET['version'];     
      $sLastModified = gmdate('D, d M Y H:i:s', $iETag).' GMT';
      
      // see if the user has an updated copy in browser cache
      if (
         (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && $_SERVER['HTTP_IF_MODIFIED_SINCE'] == $sLastModified) ||
         (isset($_SERVER['HTTP_IF_NONE_MATCH']) && $_SERVER['HTTP_IF_NONE_MATCH'] == $iETag)
      ) {
         header("{$_SERVER['SERVER_PROTOCOL']} 304 Not Modified");
         exit;
      }
      
      // create a directory for storing current and archive versions
      if (CREATE_ARCHIVE && !is_dir("$sDocRoot/".ARCHIVE_FOLDER)) {
         mkdir("$sDocRoot/".ARCHIVE_FOLDER);
      }
      
      // get code from archive folder if it exists, otherwise grab latest files, merge and save in archive folder
      if (CREATE_ARCHIVE && file_exists("$sDocRoot/".ARCHIVE_FOLDER."/$iETag.cache")) {
         $sCode = file_get_contents("$sDocRoot/".ARCHIVE_FOLDER."/$iETag.cache");
      } else {
         // get and merge code
         $sCode = '';
         $aLastModifieds = array();
         foreach ($aFiles as $sFile) {
            $aLastModifieds[] = filemtime("$sDocRoot/beta/$sFile");
            $sCode .= file_get_contents("$sDocRoot/beta/$sFile");
         }
         // sort dates, newest first
         rsort($aLastModifieds);
         
         if (CREATE_ARCHIVE) {
            if ($iETag == $aLastModifieds[0]) { // check for valid etag, we don't want invalid requests to fill up archive folder
               $oFile = fopen("$sDocRoot/".ARCHIVE_FOLDER."/$iETag.cache", 'w');
               if (flock($oFile, LOCK_EX)) {
                  fwrite($oFile, $sCode);
                  flock($oFile, LOCK_UN);
               }
               fclose($oFile);
            } else {
               // archive file no longer exists or invalid etag specified
               header("{$_SERVER['SERVER_PROTOCOL']} 404 Not Found");
               exit;
            }
         }
      }
   
      // send HTTP headers to ensure aggressive caching
      header('Expires: '.gmdate('D, d M Y H:i:s', time() + CACHE_LENGTH).' GMT'); // 1 year from now
      header('Content-Type: '.FILE_TYPE);
      header('Content-Length: '.strlen($sCode));
      header("Last-Modified: $sLastModified");
      header("ETag: $iETag");
      header('Cache-Control: max-age='.CACHE_LENGTH);
   
      // output merged code
      echo $sCode;
   } else {
      // get file last modified dates
      $aLastModifieds = array();
     
      foreach ($aFiles as $sFile) {
         $aLastModifieds[] = filemtime("$sDocRoot/beta/$sFile");
      }
      // sort dates, newest first
      rsort($aLastModifieds);
      
      // output latest timestamp
      echo $aLastModifieds[0];
   }
?>