向此Combobox添加AJAX调用以读取JSON

I'm having problems adding a XHR request to query JSON to my script, I rarely work with either so it's giving me a lot of problems. I know that I will need to query a JS file, and that I will need to select from matches in an array, but I am completely stumped on how to do it. Something else I need to do is count matches each time I fire of a request.I'm having problems adding a XHR request to que