How to Access and Formating Controls inside Datalist using javascript

function DeselectDataList(Prod_id,Qty,weightId,Gm_w)

    {

        var datalist = document.getElementById('<%=DlProducts.ClientID%>');

        var wt = datalist.getElementsByTagName("select");

        var sp = datalist.getElementsByTagName("input");

        var a = 1;

        var  j= 0;

        

         if(Qty != null) // Setting quantity for Pc and Pack case

            {

                       for (var k=0;k<wt.length;k++)

                        {

                         

                               if (wt[k].id==Qty)

                                {

                                        

                                  wt[k].selectedIndex=0;

                                  // This line is coloring Div inside Datalist

                                  wt[k].parentNode.parentNode.parentNode.parentNode.style.backgroundColor = "White";

                                  return;

                                }

                                 

                         }

           

             }

            

            

          for (var i=0;i<wt.length;i++)

          {

              if (wt[i].id==weightId)// for code behind

                  {

                    wt[i].selectedIndex=0;

                    wt[i].parentNode.parentNode.parentNode.parentNode.style.backgroundColor = "White";

                    break;

                  } 

                 

                  if (wt[i].id==weightId.id) // for javascript

                  {

                    wt[i].selectedIndex=0;

                    wt[i].parentNode.parentNode.parentNode.parentNode.style.backgroundColor = "White";

                    break;

                  }   

          }

         

          for (var i=0;i<wt.length;i++)

          {

              if (wt[i].id==Gm_w)// for code behind

                  {

                    wt[i].selectedIndex=0;

                    wt[i].parentNode.parentNode.parentNode.parentNode.style.backgroundColor = "White";

                    break;

                  }   

                 

                 if (wt[i].id==Gm_w.id) //for Code javascript

                  {

                    wt[i].selectedIndex=0;

                    wt[i].parentNode.parentNode.parentNode.parentNode.style.backgroundColor = "White";

                    break;

                  } 

          }

    }