Call JavaScript via ScriptManager in C#

Executing a block of JavaScript code from C# on the server side in ASP.NET AJAX is relatively easy to do, here in this post I will show how this can be done. The main object that you need to use is the ScriptManager via RegisterClientScriptBlock method; this method let you inject new JavaScript codes into the browser in run-time. That mean you client web browser can order to execute new task by the server ordering it, in this example I will use the DropDownList SelectedIndexChanged event to make event changes.