Where is the file processing add to cart OpenCart?

The problem is that when something is added to cart, it goes through a layout.
The treatment is Ajax + js, but can't figure out how to change it?
tell me where to look and what to look at?
July 12th 19 at 17:00
1 answer
July 12th 19 at 17:02
The link to the shop in the Studio to test the joint.

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