There's a similar question here: https://experienceleaguecommunities.adobe.com/t5/adobe-target-questions/adobe-target-order-confirmat...
To answer your question, regardless of which tracking/collection method you're using (at.js vs. webSDK), Target needs the same 3 parameters in order to deliver any purchase related criterias in Recommendations - orderTotal, orderId, productPurchaseId.
Here's an example of how to send those 3 parameters as part of the XDM object: https://experienceleague.adobe.com/en/docs/platform-learn/migrate-target-to-websdk/send-parameters#p...