Shopping Cart Like Feature

Thanks to everyone in advance for any help you can give me. I have created a purchase request app with a list of items. I would like to have users search through a table of items using filters and search fields until they find the item they need. Once the find it, I would like to have a button that adds the selected item to a purchase request list, just like an e-commerce site adds an item to a shopping cart. Any clue how I should start this? HTML to add button then js to add a new record to an existing object with selected data.

I will need to learn this from the ground up, so any help would be greatly appreciated.