How can I implement line item property capture in Shopify 2.0?

[bguse]

I am looking for advice on how to implement line item property capture at the point of adding an item to the cart.

The most simple way to do this is to just insert custom liquid/html code in the product form for whichever product I want to do this on.

From my understanding of Shopify 2.0 and "built for Shopify," Shopify is trying to make adding and removing apps more straightforward for merchants to easily integrate the apps into their stores.

The other option that Shopify documentation gives is to use an AJAX API call to insert the line item properties. the only issue with this is I don't know a simple reliable way to trigger the Ajax API call after the item has been added to the cart.

If anyone has any guidance on any other options id greatly appreciate it. 

Thanks.