How to add a "Buy" button in Bitrix?

Question

1C-Bitrix

Can you tell me how to correctly display the "Buy" button on the product detail page?
I analyzed the standard template, but did not really understand how this function is implemented.
In older versions, as I understand it, ADD_URL and BUY_URL were used, but now they do not work.
And now everything is tied to this id:
id="<? echo $arItemIDs['ADD_BASKET_LINK']; ?>"

Answer 1

Well, there is a whole script.js file in which a huge undocumented baboon is written, which is responsible for this button.
https://dev.1c-bitrix.ru/api_help/catalog/basket.php
https://dev.1c-bitrix.ru/community/webdev/user/516...