Hi,
In the product page, the function "hikashopToggleFields" is added by the call of the function jsToggle by the lines
$fieldsClass->jsToggle($itemFields,$element,0);
in the file "components/com_hikashop/views/product/view.html.php".
In the checkout page, the function "hikashopToggleFields" is added by the call of the function jsToggle by the lines
$fieldsClass->addJS($null,$null,$null);
$fieldsClass->jsToggle($this->extraFields['user'],$user,0);
$fieldsClass->jsToggle($this->extraFields['address'],$address,0);
in the file "components/com_hikashop/views/checkout/view.html.php".
The function "hikashopCheckMethods" is added directly by the view "components/com_hikashop/views/checkout/view.html.php", in the function "step".
So if the javascript is not present in the final page and the code is still present in your HikaShop code ; it means that you have some kind of system plugin (or maybe a feature of the template) which remove it.
Regards,