Select/Unselect All inside griview with modal popup using javascript with Color selected rows

//Gridview

<asp:TemplateField >

 <ItemTemplate>

 <asp:CheckBox runat="server" ID="Chk_allCh" />

  </ItemTemplate>

 <HeaderTemplate>

 <asp:CheckBox runat="server" ID="Chk_all" onclick="checkAllRow(this);" />

</HeaderTemplate>

</asp:TemplateField>

//Script

function checkAllRow(objRef) {

       var GridView = objRef.parentNode.parentNode.parentNode.parentNode.parentNode;

       var inputList = GridView.getElementsByTagName("input");

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

           //Get the Cell To find out ColumnIndex

           var row = inputList[i].parentNode.parentNode;

           if (inputList[i].type == "checkbox" && objRef!= inputList[i]) {

              if (objRef.checked) {

       //If the header checkbox is checked//check all checkboxes//and highlight all rows

                 row.style.backgroundColor = "#5CADFF";

                 inputList[i].checked = true;

                }

           else {

       //If the header checkbox is checked//uncheck all checkboxes//and change rowcolor back to original

               if (row.rowIndex % 2 == 0) {

                //Alternating Row Color

                  row.style.backgroundColor = "#AED6FF";

                  }

                  else {

                   row.style.backgroundColor = "white";

                     }

                      inputList[i].checked = false;

                           }

                       }

                   }

               }