Use AJAX to validate a field

[eluser]xcristi[/eluser]
Hello guys,

So, I know little about AJAX, but I need to implement such thing in a CI application. I just need from some directions, because I'm a little confuse here...

I have a form (view) with a input text field, let's say 'name' and a DB with a table that contains field 'names'. What I want to do is to verify the value entered for name in table and display a message 'No duplicate' or 'Duplicate name' (or something like that).

I load the library ajax but I haven't an idea what to put into view and what into controller. Maybe you could show me some direction to follow.

Thanks.