You cannot call server-side code ‘directly’ from client-side code. That is because by design, the server side code executes at server side and client side code at the client. However there are some workarounds. To call serverside code from javascript, you will need to use AJAX, and the easiest way out, is to use the ASP.NET AJAX Extensions. In this article, we will be using PageMethods to call server-side functions using javascript.