ASPxCallback Example

 <dxcb:ASPxCallback ID="ASPxCallback1" runat="server" ClientInstanceName="Callback1" OnCallback="ASPxCallback1_Callback">
     <ClientSideEvents CallbackComplete="function(s, e) {
         var element = GetDetailsContainer(e.parameter);
         element.innerHTML = e.result;
     }" />
 </dxcb:ASPxCallback>
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  protected void ASPxCallback1_Callback(object source, CallbackEventArgs e) {       
         string xpath = string.Format("//items/item[@newsID='{0}']", e.Parameter);
         XmlNode node = XmlDataSource1.GetXmlDocument().SelectSingleNode(xpath);
         if (node != null)
             e.Result = node.Attributes["Description"].Value;
     }
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function GetDetailsContainer(id) {
    return document.getElementById("details" + id.toString());
}        
function ShowDetails(id) {
    GetDetailsContainer(id).style.paddingTop = "14px";
    GetDetailsContainer(id).style.paddingRight = "12px";
    GetDetailsContainer(id).innerHTML = "Loading…";
    Callback1.PerformCallback(id);
}