Some times we need to call server side function from Javascript function.For example,callig a PoupWindow(with value from code behind) on HyperLink click. 

This must be implemented by creating a additional request to the web server and that’s the only way to invoke methods on the server. Page methods are used for this.

What is PageMethod?

A PageMethod is a public static method that is exposed in the code-behind of a page and can be called from the client script. PageMethods are annotated with [System.Web.Services.WebMethod] attribute.

The code is simple..

Server side function

[code:c#]

[System.Web.Services.WebMethod] public static void Score(string ID, string name, string Role) {

         try {

                //Some data manipulations 

                  return finalScore ; 

              }

         catch (Exception ex) { 

               //Response.Write(ex.ToString());

                                  } 

            } 

[/code]

//Client Side function 

[code:c#]

function score()

              {               

                  PageMethods.Score(txtID.value,txtName.value,txtRole.value);            

               } 

[/code]

<asp:HyperLink ID="btn_Test" runat="server" Text="Calculate" OnClientClick="javascript:return score();"/>