$.ajax({
                     type    : "POST",
                     url     : "?",
                     dataType: "json",
                     data    : "username=" + encodeURIComponent($('input[name="username"]').val()) + "&password=" + encodeURIComponent($('input[name="password"]').val()) + "&antiForgeryToken=d98188e0f56bafa75180591e38d189ee",
                     success : function(json) {
                         if(json.status == 'success') {
                             window.parent.location.href = json.returnUrl;
                             window.parent.$.fancybox.close();
                         } else {
                             $('#slfErrorAlert').show();
                             $('.spispinner').hide();
                             $maindiv.removeAttr("disabled");
                             $maindiv.removeClass("instaclass31");
                         }
                     }
                 });
      });

$browser = new SimpleBrowser();
$str = '?username=aaa&password=bbb&antiForgeryToken=d98188e0f56bafa75180591e38d189ee';
$json = json_encode($str);
$browser->post($httpsPage, $json);