Just the idea: you can choose to remove auto postback and write explicit Ajax post in your handler of your
OnChange
event handler.
I would perfectly understand that you want both the postback and this event. Probably, you first do some local processing on the client side using this event and newly updated value of the text box (entered text) with JavaScript, and then you need to notify the server by sending the HTTP request. When HTTP server processes the request, new updated part of page is generated out of HTTP response and the cycles starts over.
If this is your scenario, it can be quite reasonable; this is what Ajax is actually used for. At the same time, I would advise you to review it, as the event
OnChange
can be too frequent. You need to consider performance cost of the exchange with the server on each event. Overuse of Ajax is actually a curse of many present-days site: developers make them actually working, but they don't care about how much it costs due to wildly redundant traffic use.
Nevertheless, if you still decide to keep to having both client-side event handling and postback on each event, you can remove auto postback and send Ajax HTTP request in the JavaScript code of you event handler. One of the possible ways to do it is using jQuery Ajax methods. Please see:
http://api.jquery.com/category/ajax/[
^].
Good luck,
—SA