How to give absolute url

How to give absolute url

Here jquery code below,
1) how can i give absolute url to call GetDate method of default.aspx page?


the problem  is that,  if my page is in a folder and  accessing the Default.aspx page method.then
it give error object not found, because my Default.aspx page is out side of the folder in which folder
page it accessing the Default page method.

2) Is it possible to call a method which is in a class(not a .aspx page) or in a master page of .NET
    (method declared as Web Method)?

 $.ajax({
                        type: "POST",
                        url: "Default.aspx/GetDate",
                        data: "{}",
                        contentType: "application/json; charset=utf-8",
                        dataType: "json",
                        success: function (msg) {
                        
                        }
                    });