Google Suggest

The new Google Suggest function provides auto-complete to your web search queries.

It’s actually quite straight-forward stuff. A condensed JavaScript disables the browser’s auto complete in the search field and defines a hidden div field. The div body is populated at each character while you type. It’s really too fast to be doing a full Google search and postback, so I guess they keep an in-memory list of the most popular searches while using XMLHttpRequest to run queries.

This will not be the last time we see this technique.

Update: The technique was named Ajax by Jesse James Garrett in February 2005.