I have chain of drop down like Country / state and City. Is there is any way to wait until the drop down population then proceed further? like first load the country and then based on the select of an country then load the state and same as city....

function populateLists(listType) {

            // on success do this:<br>
            $.ajax({
            type:"POST",
            url:"Wizard_Using_PageMethod.aspx/GetCountry",
            data: "{}",
            contentType: "application/json; charset=utf-8",
            dataType:"json"
                } 

            });

[WebMethod]
public static CountryList GetCountry()
{
CountryList country = new CountryList();
///go to db and get the data
return country;

}