function _drupal_flush_css_js

Helper function to change query-strings on css/js files.

Changes the character added to all css/js files as dummy query-string, so that all browsers are forced to reload fresh files. We keep 20 characters history (FIFO) to avoid repeats, but only the first (newest) character is actually used on URLs, to keep them short. This is also called from update.php.

File

includes/common.inc, line 3873

Common functions that many Drupal modules will need to reference.

Code

function _drupal_flush_css_js() {
  $string_history = variable_get('css_js_query_string', '00000000000000000000');
  $new_character = $string_history[0];

  // Not including 'q' to allow certain JavaScripts to re-use query string.
  $characters = 'abcdefghijklmnoprstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
  while (strpos($string_history, $new_character) !== FALSE) {
    $new_character = $characters[mt_rand(0, strlen($characters) - 1)];
  }
  variable_set('css_js_query_string', $new_character . substr($string_history, 0, 19));
}