How we will call c# function from java script function.

One way:

Add a hidden asp:Button to your aspx page (don't forget to add a click handler in your code behind), and from your javascript, just call the button's click method:

var button = document.getElementByID("buttonID");  
button.click(); 

Your click handler code can then call the desired c# method.

http://msdn.microsoft.com/en-us/library/aa720099(vs.71).aspx[^]

Code Project article[^]

http://www.devx.com/webdev/Article/28451/0/page/2[^]

1. Try setting

EnablePageMethods="true"

in the script manager tag

<asp:scriptmanager id="ScriptManager1" runat="server" enablepagemethods="true" xmlns:asp="#unknown" />

2. To enable the method as a PageMethod, add the attribute [WebMethod] on top of the method
3. Page methods needs to be static in code behind
4. Javascript Calling:

// Your Code Behind method
PageMethods.Method1(CallSuccess, CallFailed);

//Success Method
function CallSuccess(res, destCtrl)
 {     
    Alert(res);
 }
 
 // alert message on some failure
 function CallFailed(res, destCtrl)
 {
     alert(res.get_message());
 }