JS市无刷新联动,该如何处理

JS市无刷新联动
自己对JS不是蛮熟，然后现在要把市实现无刷新联动，我自己在cs文件里已经写出了刷新联动，然后要把市实现无刷新联动
这是CS里面的代码

这是显示默认的

C# code

if (!IsPostBack)            {                RegionalInformation ri = new RegionalInformation();                                string[][] allProvinces = ri.GetProvinces();                for (int i = 0; i < allProvinces.Length; i++)                {                    ListItem lip = new ListItem(allProvinces[i][1], allProvinces[i][0]);                    DDLProvince.Items.Add(lip);                                    }                string[][] citiesOfProvince = ri.GetCitiesOfProvince("1");                for (int j = 0; j < citiesOfProvince.Length; j++)                {                    ListItem li = new ListItem(citiesOfProvince[j][1], citiesOfProvince[j][0]);                    DDLCity.Items.Add(li);                }           }

C# code

protected void DDLProvince_SelectedIndexChanged(object sender, EventArgs e)        {            RegionalInformation ri = new RegionalInformation();            string a = Convert.ToString(DDLProvince.SelectedIndex + 1);            string[][] citiesOfProvince = ri.GetCitiesOfProvince(a);            DDLCity.Items.Clear();            for (int j = 0; j < citiesOfProvince.Length; j++)            {                ListItem li = new ListItem(citiesOfProvince[j][1], citiesOfProvince[j][0]);                DDLCity.Items.Add(li);            }        }

HTML code

 <asp:DropDownList ID="DDLProvince" runat="server" CssClass="select"                AutoPostBack="True" Height="22px"                onselectedindexchanged="DDLProvince_SelectedIndexChanged" Width="150px">           </asp:DropDownList>           <asp:DropDownList ID="DDLCity" runat="server" CssClass="select"                CausesValidation="True" Height="22px" Width="150px">           </asp:DropDownList>