Caching Autocomplete Responses Using Lodash

I've taken a few approaches to caching responses in the jQuery UI autocomplete widget. A response, in autocomplete parlance, is the data that's displayed when the user is typing in the text input. Each keystroke is a request for data — the response is something the autocomplete must generate by filtering some data source. The filtering operations can be done locally, or remotely. Either way, we stand to benefit from caching these responses.