ASP.NET Button click Event in javascript using JSON

Question

I have below code which is working fine. I have to run two different server side function (which can not be run on the same time i have differentiated).

1. Default.aspx/AddCart
2. btnUpdate Click Event

My Problem is alert box coming & loading div(#overlay) is hiding before btnUpdate Click Event completion. I dont want to come alert message box & want to show loading div until Click Event not completed.

$("#overlay").show();
$.ajax({
    type: "POST",
    url: "Default.aspx/AddCart",
    data: "{id: " + selectValue + ", qty:" + qq + "}",
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function (r) {
        document.getElementById("<%= btnUpdate.ClientID %>").click();
        alert("Added to Shopping Cart  !");
        $("#overlay").hide();
    },
    error: function (r) {
        alert(r.responseText);
        $("#overlay").hide();
    },
    failure: function (r) {
        alert(r.responseText);
        $("#overlay").hide();
    }
});

Answer 1

In you button click event, add these line at last.

string script = "alert('Added to Shopping Cart  !'); $('#overlay').hide();"
ScriptManager.RegisterStartupScript(Page, typeof(Page), "sc", script, true);

and remove them from jquery, after click is called.