Auto version js and css

.htaccess

<IfModule mod_rewrite.c>
	RewriteRule ^(.*)\.[\d]{10}\.(css|js)$ $1.$2 [L]
</IfModule>

autoversion.php

  /**
	 *  Given a file, i.e. /css/base.css, replaces it with a string containing the
	 *  file's mtime, i.e. /css/base.1221534296.css.
	 *
	 *  @param $file  The file to be loaded.  Must be an absolute path (i.e.
	 *                starting with slash).
	 */
	public static function auto_version($file)
	{
		$file = strpos($file, '/') === 0 ? $file : "/{$file}";
		if(!file_exists($_SERVER['DOCUMENT_ROOT'] . $file))
			return $file;

		$mtime = filemtime($_SERVER['DOCUMENT_ROOT'] . $file);

		return preg_replace('{\\.([^./]+)$}', ".$mtime.\$1", $file);
	}