I'm using VS2010,C# to develop my ASP.NET web app. I have some a combo box for selecting province and another combo box for selecting cities, when user selected a province, the city combo box should immediately display cities belonging to that province. I have inserted an AJAX script manager into my page, also an AJAX update panel (both from toolbox) in which I've inserted my combo boxes. Then I enabled province combo box autopostback property so that when user changes his selection, I can detect it and change contents of city combo box accordingly. It works fine, as I load province and city names from my database into a list at page startup (of course this load process is performed in a if(!IsPostback) statement so that data is loaded only once). I think the time needed to update city combo box is a bit more than what is required, as there is a postback when user changes province combo box selection, what is the best (and correct) way of performing this operation? is it ok? are there any better ways of doing it? how can I IMMEDIATELY update city combo box after province combo box selection is changed, as currently there is a short delay.
thanks