noCache.php

<?php
$file = isset($file) ? $file : '';
$cacheable = isset($cacheable) ? intval($cacheable) : 0; // 1 or 0

if (empty($file)) {
	return;
}

$filePath = MODX_BASE_PATH . $file;

if (!file_exists($filePath) || !is_readable($filePath)) {
    return;
}

$md5File = '';
if ($cacheable === 0) {
	$md5File = '?nocache='.md5_file($filePath);
}

return $file.$md5File;