Hi Mayon,
You can checkout the Velo API,
https://www.wix.com/velo/reference/wix-stores/getcurrentcart
This event is triggered when the cart page is loaded.
https://www.wix.com/velo/reference/wix-stores/oncartchanged
This event is triggered when the cart is updated.
So, if user apply a coupon on cart page, you can show the banner to make user excited ![]()