for http://stackoverflow.com/q/23369252

gistfile1.js

var iframesLoaded = 0;

$("form").each(function() {

  var $form = $(this);
  var $iframe = $("<iframe name='temporary-iframe'></iframe>");

  var oldTarget = $form.prop("target");
  $form.prop("target", "temporary-iframe");

  $iframe.hide();
  $("body").append($iframe);
  $iframe.on("load", function() {
    iframesLoaded += 1;
    // update loading bar based on this?
    $iframe.remove();
  });

  $form.submit();
  $form.prop("target", oldTarget);

});