Cascaded dropdown using jQuery

$(document).ready(function() 
    { 
        var Result;
       var Error;
       //var Parameters="{'x':'dave','y':'himanshu'}"; //Hardcode Parameters
       var xx='Himanshu1';
       var yy='Himanshu2';
       var Parameters="{'x':'"+xx+"','y':'"+yy+"'}"; //Dynamic Parameters
 $('.AJAX').click(function(e)
        { 
            CallAJAX(this.ServerMethod,Parameters,this.SuccessMethod,this.ErrorMethod,'#'+this.TargetControl,this.Item,this.Description);
            return false;
        }
    ); 
    
     $('.FillDD').change(function(e)
        { 
            if (parseInt($('#'+this.id).val())>0)
             {    
              var Parameters="{'Param':'"+document.getElementById(this.id).value+"'}";
              CallAJAX(this.ServerMethod,Parameters,this.SuccessMethod,this.ErrorMethod,'#'+this.TargetControl,this.Item,this.Description);
             }
             //   return false;
        }
    );
 
     function CallAJAX(ServerMethod,Parameters,SuccessMethod,ErrorMethod,ControlID,Item,Description)
     {
       $.ajax({
              type: "POST",
              url: ServerMethod,
              data:Parameters,
              contentType: "application/json; charset=utf-8",
              dataType: "json",
              error: function(xhr, status, errorThrown)
              {
                   Error=xhr;
                   eval(ErrorMethod + "()");
              },
              success: function(msg) 
              {
                   Result =msg;
                   var rr=  SuccessMethod + "('" + ControlID + "','" + Item + "','" + Description + "');";
                   eval(rr);
                   //eval(SuccessMethod + "()");//without parameter
              }
           });
      }
 
     function outputDT(ControlID,Item,Description)
     {
      BindDropdown(ControlID,Item,Description);
     }
      
      function BindDropdown(ControlID,Item,Description)
      {
            var opt='';
           opt += '<option value=-1>'+"---Select---"+'</option>';
            if(Result.d.Table.length>0) 
            {       
                for (var row in Result.d.Table)
                {
                
                 opt += '<option value="' + eval('Result.d.Table[row].'+Item)+ '">' + eval('Result.d.Table[row].'+Description) + '</option>';
                } 
            }
            else 
            { 
             opt ='<option>Sorry,No Record Found</option>'; 
            }  
           $(ControlID).html(opt); 
         
      }
      
        function ShowError()
        {
        alert(Error.responseText);
        }
      
     });