Question

Ok, so I have been spinning my wheels on this one for a long time now, and as usual, i am sure that this is a really simple fix, so here goes…

I need to set a javascript variable using a variable from my code-behind file. Normally, I do it as follows:

var Test = <%= TestVar%>

On a normal page load, this method (while probably not the best way to do it) works great for me. The problem that I am now having, is that I need to change the variable on a callback with a callback/update panel. What I have, is the variable is set in a javascript block in the page header, and I then call a function that utilizes the variable on the callback panel’s EndCallback event.

var Var1 = <%= Var1%>;
function endCallback()
{
    //some action with Var1;
}

Everything runs great, except that the server tag is not reloaded (because I am not doing a full page postback). Is there a better way to update a javascript variable on a partial postback?

Answer 1

If you want to change a server variable, you need an ajax call.
Using jquery or another method.
On server-side you need to create a method, maybe a web service. And then invoke it from the client-side sending the new value.

client side:

$.ajax({
   url: "(webservice url)",
   data:(parameters if needed),
   success:function(response){
        variable = response;
   }
});

server-side:

[WebMethod()]
public object GetValue(object param1){
   ...
   return new_value;
}