set session values using javascript

Refer:-session in javascript in asp.net[^]
Check Solution 2 and Solution 3.
This may help.

Hey

You can set Session variables using Javascript like this

<script type="text/javascript">
function SetUserName()
{
    var userName = "Shahid Bhat";
    '<%Session["UserName"] = "' + userName + '"; %>';
     alert('<%=Session["UserName"] %>');
}
</script>

And you can retrieve the values like this

<script type="text/javascript">
    function GetUserName()
    {

        var username = '<%= Session["UserName"] %>';
        alert(username );
    }
</script>

What exactly do you mean by passing label values. You can set the properties of label from the code behind simply like

lblUserName.Text="Shahid Bhat" // Where lblUserName is the ID of the label.

create a code behind method like below

[WebMethod]
   public static string SetSession(string sessionval)
   {
     Session["mysession"]=sessionval;
   }

call it using ajax

<script>
function  SetValue(myval)
{
   $.ajax({
   url:"YourPageName.aspx/SetSession",
  Type:'POST',
  data:{sessionval:myval},
  success:fucntion(response){}
});
}

<script></script></script>

Hope this helps!!!