How to pass ASP.NET server side tags with JS parameters

Question

I have a loop in JS, and I want to pass each parameter in that loop to a function in ASP.NET in the codebehind.

something like that:

for (var i = 0; i < elements.length; i++)
    {                    

    }

And I want to pass a function in <%%> the elements[i].

How can I do that?

thanks!

Answer 1

It's not that easy, the only way is to make a post and send the variables.

What I normally do is to have a handler to do the job for me and using jQuery I get a nice pretty effect...

from your javascript code

var r = '';
for (var i = 0; i < elements.length; i++)
    r += elements[i] + ',';

// send this asynchronously to the handler
$.get("myHandler.asmx", { values: r }, function(data) {
  // it finished processing, let use the passed data
  alert(data);
});

in your handler

public void ProcessRequest(HttpContext context)
{
    string r = context.Request["values"];

    // process them

    context.Response.ContentType = "text/plain";
    context.Response.Write("OK");
}

that "OK" will be passed to the data variable, and you can interact your user with a much more rich environment.

Answer 2

If you mean you would like to call a server side method from the client then there is an easier way, using Page-based web services:

In your code behind add a method as follows:

[WebMethod]
public static void MyMethod (string s)
{
}

It is necessary to use EnablePageMethods=true in the page's script manager, ie

<asp:ScriptManager runat="server" ID="ScriptManager1" EnablePageMethods="true">

Then in your client code you can use:

PageMethods.MyMethod (s, MyMethodSuccess, MyMethodFail);

function MyMethodSuccess() { }

function MyMethodFail(error) {
    alert(error.get_message());
}