Hi Lightning Now! community, 

Very interested in migrating my company's instance over to this new experience. However, it will be awhile until we move over. 

I have a javascript button in Classic that uses prompt() to ask the user which product bundle they wish to select. Upon inputing the desired bundle (see image attached for example), the JS button uses an AJAX toolkit to query the correct PricebookEntries and insert it into the Opportunity. 

My question:

I understand AJAX and JS buttons are not supported in Lightning. How would I redesign this button to be Lightning ready, but still work in Classic for the time being ?