Question

What I was trying to do here is to call a function from client, which will call “RaiseCallbackEvent”, and I tried to stored the argument(from client) into viewstate. Yet, the viewState is never saved during the callback , why?

        public partial class _Default : System.Web.UI.Page, System.Web.UI.ICallbackEventHandler
        ....
        protected void Page_Load(object sender, EventArgs e)
        {

        ClientScriptManager cm = Page.ClientScript;
        String cbReference = cm.GetCallbackEventReference(this, "arg",
            "ReceiveServerData", "");
        String callbackScript = "function CallServer(arg, context) {" +
            cbReference + "; }";
        cm.RegisterClientScriptBlock(this.GetType(),
            "CallServer", callbackScript, true);
        }
       .....
       public void RaiseCallbackEvent(String eventArgument)
       {
           ViewState["attribute"] = eventArgument;
       }
       .....

Answer 1

The ViewState isn’t available to javascript; however, the Cache is.