I am using `Asp.Net/C#` , I need to fill a dropdownlist on change of another dropdownlist , I could have done it using `SelectedIndexChanged` event by setting `AutoPostBack` Property to `True` of the first dropdownlist , but I have a password textbox which gets cleared on postback , so that solution was not feasible.I decided to use `jquery ajax` to call my `code behind method` , but I am using this approach for the first time so I cant figure out how do I go about this.Here is what I have tried so far but it is not working for me.

```
$('#ddlDivisionName').change(function() {
        alert('j');
        $.ajax({
            type: "POST",
            url: "/CreateAccount/CreateAccount.aspx/BranchNameFill",
            data: "{'index':1}",
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            async: true,
            cache: false,
            success: function() {
                alert('ok');
            }
        })
        return false;
    });

[WebMethod]
        public static string BranchNameFill(int index)
        {

            ddlBranchName.Items.Clear();   
            IEnumerable<BRANCH> br;
            br = (from b in dt.BRANCHes
                  where b.DIVNO ==index
                  select b);
            for (int i = 0; i < br.Count(); i++)
            {
                ddlBranchName.Items.Add(br.ElementAt(i).NAME.Trim());
            }

        }

```