Change quantity in the product sheet through JavaScript

[sergiorx8]

Good evening guys, I'm writing to see if you can help me with my PrestaShop 1.7. I need to update the product quantity within a product page using JS. It could be added easily in the beginning with a code like this: $ ("# quantity_wanted"). Val (4). The problem is that this alone is not valid since PrestaShop does not recognize this change in quantity since if I do this and click the add to cart button, it adds quantity 1 and another very important thing is that the total price does not change either. All this is done correctly if it is done manually by hitting the + and - button since it seems that it does a kind of ajax loading when pressing those buttons.

From what I have read (https://devdocs.prestashop.com/1.7/themes/reference/javascript-events/) I think it could be done through PrestaShop JavaScript events but no matter how much I try, I can't find the solution. So far what I have achieved is this but it does not work either since neither the total price changes nor PrestaShop recognizes that the amount has changed.

prestashop.emit('updateProduct', {
     eventType: 'updatedProductQuantity',
     event: $("#quantity_wanted").val(4)
 });

Any ideas?