gistfile1.js

$(function() {
 
    $('#countries').change(function() {
        var selectedValue = $(this).val();
 
        var targeturl = $(this).attr('rel') + '?id=' + selectedValue;
        $.ajax({
            type: 'get',
            url: targeturl,
            beforeSend: function(xhr) {
                xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
            },
            success: function(response) {
                if (response.content) {
                    $('#states').html(response.content);
                }
            },
            error: function(e) {
                alert("An error occurred: " + e.responseText.message);
            }
        });
    });
 
});