Question

What i am trying to do is get a user to change one drop down, which then calls an ajax function which posts to the code behind (vb.net file) then clears and populates another asp dropdown list with the data returned from the function..hope i made sense

<script>
  $(document).ready(function () {
        $('.manuf').change(function () {
             $.ajax({
                      type: "POST", 
                      url: "ajax.aspx/GetModel",
                      data: '{' +
                            'ManufID:"' + $('.manuf').val() + '"' +
                           '}',
                      contentType: "application/json; charset=utf-8",
                      dataType: "json",
                      success: function(msg) {
                         var data = json_parse(msg.d);
                         if (data.error) {
                              alert("Error!");
                              return;
                         }

                          alert(data.model);
                      },
                      error: function(msg) {
                          alert('Get Details Failure: ' + msg);
                      }
                  });
        });
    });

</script>  

Answer 1

My bad – you can write your ajax call like this –

$.ajax({ url :"/website/myurl", type:"POST", contentType:"application/json;", dataType:"json", data : "{ 'id' : '" + $("select[id*=selCurrentManuf]").val() + "' } ",
        success : function (return_data) {
             var data = $.parseJSON(return_data);
             // code to add the contents of data to other list
             $("select[id*=selCurrentModel]").empty().append($("<option>").attr("value","0").text("Choose..."));
             // for the dropdown list clear all options and add a 'choose...' as the first option

            $.each(data, function (i, d) { $("<option>").attr("value", d.k).text(d.v).appendTo($("select[id*=selCurrentModel]")); });

}, error:function () {
             // handle error
            }     
    });