$design = erLhcoreClassDesign::getInstance();
$design->addJSFile('path/to/file.js');
$design->addCSSFile('path/to/file.css');
$design->setTemplate('path/to/template.tpl.php');The erLhcoreClassDesign class is a part of the Live Helper Chat package library, which is a collection of PHP classes and functions used for building chat applications. This package library also includes other classes such as erLhcoreClassChat, erLhcoreClassUser, erLhcoreClassFormValidator, and more.