This script is based on jQuery Autocomplete plugin made by PengoWorks.
It has many options and is quite easy to setup in your page.
You can pass advanced options as a JavaScript object, hashes etc.
It’s easily to edit the style of the dropdown result box, there are a couple of css classes.

- You can use local arrays of data (in javascript arrays), so you don’t have to use AJAX to query your server
- Limit you number of results dropdown to XX (good for limiting the results to users)
- Autofill pre-populates text box as you type
- New findValue() method can be used to programmatically determine if the value in the box is a valid option. (Useful for verifying the text entered is an existing value option.)
- Dropdown options now correctly re-position themselves on each display (which means they adjust for changing to the DOM)
- Dropdown box defaults to the width of the input field its attached to (you can manually specify a larger width as well)
- Better emulates Windows autocomplete boxes (for example: hitting delete and retyping the same box will now bring back the dropdown menu)

Download this script: jquery-autocomplete