Consider the ajax request :
var idNumber = $("#Field_1").val();
var servletUrl = "someURL"; // some url goes here
$.ajax({ 
    url: servletUrl,
    type: 'POST',
    cache: false, 
    data: { }, 
    success: function(data){
        alert(data);
        window.location = "./replyToYou.html";
    }
    , error: function(jqXHR, textStatus, err){
        alert('text status '+textStatus+', err '+err + " " + JSON.stringify(jqXHR));
    }
});
How can I pass , on success idNumber to replyToYou.html , and how can I grab it in replyToYou.html ? 
Much appreciated
 
     
     
    