In Shopify I made a custom app in php. And now I need to make logic that will work on the checkout page.
In fact, I need to change the UPS delivery price conditionally, which means I need to catch or simulate the event of assigning the delivery price to the product price.
Can please tell me how I can execute my php code, written in index.php, on the checkout page? Or how and where can I link my php code to page checkout?
There is absolutely no information on this in the shopify documentation! In the Shopify Dev documentation, I’ve seen scripts for wasm - https://shopify.dev/apps/checkout/shipping-methods, but that’s not what I need.
I hope very much for your help! Thanks!