How to use event observer and raido buttons

Rails
1

Hi list,

I am new to rubyonrails any help is very appreciated.
In my view I have two radio buttons and based on their value I need to
invoke different part of the same view.
I wonder how can I check the if these raido buttons were selected.
I think I need to use “event observer” and “ajax” but I can not make it
works.
so far I have this:

and in public/javascripts/application.js

function chkShowItem($sChk){

if($sChk == true )
return 0;
else
return 1;

}

However I don’t know how to check the value that is returned by
chkShowItem or even if this is the correct approach.

Thanks