This is a TYPO3 CMS extension to render native handlebars templates

Within the extension there are a few Handlebars helpers configured by default, such as content, block, json, lookup. On the top of that we can add new custom handlebars helper which can be declared in ext_localconf.php as follows

\Visol\Handlebars\HelperRegistry::getInstance()->register(
    'foo', 
    function ($labels, $key) {
        return $labels[$key];
    }
);