This is how you'd make an AJAX request to the current controller in Yii.
filter_info is the variable with the text you want to send to the controller.
EDIT:. Some time ago I noticed that empty urls(like what I've used here) may cause some trouble on IE browsers. I am not sure whether this is still the case but, just in case it still is, it might be better to use
location.href rather than
"" as the url here.