1$.when(ajax1(), ajax2(), ajax3(), ajax4()).done(function(a1, a2, a3, a4){
2    // the code here will be executed when all four ajax requests resolve.
3    // a1, a2, a3 and a4 are lists of length 3 containing the response text,
4    // status, and jqXHR object for each of the four ajax calls respectively.
5});
6
7function ajax1() {
8    // NOTE:  This function must return the value 
9    //        from calling the $.ajax() method.
10    return $.ajax({
11        url: "someUrl",
12        dataType: "json",
13        data:  yourJsonData,            
14        ...
15    });
16}

1		$(document).ajaxStart(function () {
2            $('#ajax-loading-image').css("display", "block");
3        });
4        $(document).ajaxStop(function () {
5            $('#ajax-loading-image').css("display", "none");
6        });