Currently the default behaviour is if i have item X in the cart with qty 5, if i put 8 in the qty box and add to cart the new qty is 13 - the expected behaviour we need to for the cart to change to 8 rather than add the 8.
As the category page is using a .js file rather than a phtml file to handle a lot of the customisation it is required somehow to either do this from an observer file seperate from the .js file or an ajax request to a controller in the .js file (this would be prefared).
i have attempted to do AJAX request with no luck, with the URL not being found no matter what i try (i asked the question about this here with no luck)
After failing with this i had the idea to use checkout_cart_product_add_before observer event, remove the item from the cart and re-add it with the new value but when i use
It is refreshing the whole page and losing the addition.
Does anyone have any ideas on how i can achieve this? i did manage it with a widget previously but now its been required to be a category page it's become a little more difficult.