AJAX - Powered AutoComplete (for Prototype.js)

The AutoComplete class adds a pulldown menu of suggested values to a text field. The user can either click directly on a suggestion to enter it into the field, or navigate the list using the up and down arrow keys, selecting a value using the enter key. The values for the suggestion list are to provided as XML, or as JSON (by a PHP, ASP, ASPX script, or similar). The results of the first request are cached on the client machine and are filtered as the user continues to type, to reduce the number of requests hitting the server.