A way to pass autocomplete results to JavaScript

Issue Summary

I'm looking for a way to pass the ASIN from function asin_autocomplete_callback($string = '') to a JavaScript running on the same form.
Right now I have a JavaScript that run after someone types in the ASIN, then clicks a search button. The script pulls the data from Amazon, and fills in the rest of the form. What I'd like to try, is if someone doesn't know the ASIN, they can type the name, and then select from the autocomplete results. Then if they click the search button, the JavaScript gets the ASIN to search directly from the autocomplete results.