I’m using the jQuery UI autocomplete functionality and, while I’ve found a way to implement the autoFill function, I was looking for functionality like in the Google Chrome address bar. Where the best matching item is auto-filled, but it doesn’t interrupt your typing.

Any help is appreciated.
I suggest you look at the older jQuery autocomplete plugin, which offers this option built in. The syntax is similar, but instead of having the source as a option you instead initialized it as the first parameter, with this syntax:
The
datamust be either an array of results, or an url that points to a server-side script that generates it. For more info see its documentation: http://docs.jquery.com/Plugins/AutocompleteDo note however that the author of this plugin consider it obsolete, and the jQuery UI autocomplete to be its successor. In a ‘How to migrate’ post he points users now to, the rational jQuery UI not having the
autofilloption is explained: