If your code whatever you have posted here is correct, following line will produce an error -
1. Extra white space -
var str = document.getElementById(' CountryAndCity ').value;
And, the reason is extra whitespaces in argument to the document.getElementById() [
http://jsfiddle.net/4Vsxy/[
^]]
And, one advice here. If you are using jQuery writing this expression makes it odd as you can very well use
var str = $('#CountryAndCity').val();
2. If you code works, and you are getting error in ajax call you need to look into the details of GET request using firebug, fiddler or any other tool. That would not be much difficult.
3. If everything works fine and you are getting error due to getting null value in the hidden field "
hidMyModelid_city" which you are using then this will work-
$('#hidMyModelid_city').val(result);
as, you haven't included # in the selector you are providing (I guess its an id for sure).
I hope this would work for you. :)
Thanks