old_contents: $(document).ready(function () {
      $(document).ajaxStart(function () {
          //console.log("add");
          $(".ajax-loader").fadeIn("slow")
          $(".ajax-loader-background").fadeIn("fast")
          $(".ajax-loader-foreground").fadeIn("fast")
      });
      $(document).ajaxStop(function () {
          //console.log("remove");
          $(".ajax-loader").fadeOut("slow")
          $(".ajax-loader-background").fadeOut("100")
          $(".ajax-loader-foreground").fadeOut("100")
      });
  });
  
new_contents: $(document).ready(function () {
      $(document).ajaxStart(function () {
          //console.log("add");
          $(".ajax-loader").fadeIn("slow")
          $(".ajax-loader-background").fadeIn("0")
          $(".ajax-loader-foreground").fadeIn("0")
      });
      $(document).ajaxStop(function () {
          //console.log("remove");
          $(".ajax-loader").fadeOut("slow")
          $(".ajax-loader-background").fadeOut("50")
          $(".ajax-loader-foreground").fadeOut("50")
      });
  });
  
subject: adjust loader indicator fade in / out