diff -r 07239de796bb -r e756a8c72c3d cms/drupal/misc/progress.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cms/drupal/misc/progress.js	Fri Sep 08 12:04:06 2017 +0200
@@ -0,0 +1,106 @@
+(function ($) {
+
+/**
+ * A progressbar object. Initialized with the given id. Must be inserted into
+ * the DOM afterwards through progressBar.element.
+ *
+ * method is the function which will perform the HTTP request to get the
+ * progress bar state. Either "GET" or "POST".
+ *
+ * e.g. pb = new progressBar('myProgressBar');
+ *      some_element.appendChild(pb.element);
+ */
+Drupal.progressBar = function (id, updateCallback, method, errorCallback) {
+  var pb = this;
+  this.id = id;
+  this.method = method || 'GET';
+  this.updateCallback = updateCallback;
+  this.errorCallback = errorCallback;
+
+  // The WAI-ARIA setting aria-live="polite" will announce changes after users
+  // have completed their current activity and not interrupt the screen reader.
+  this.element = $('<div class="progress" aria-live="polite"></div>').attr('id', id);
+  this.element.html('<div class="bar"><div class="filled"></div></div>' +
+                    '<div class="percentage"></div>' +
+                    '<div class="message">&nbsp;</div>');
+};
+
+/**
+ * Set the percentage and status message for the progressbar.
+ */
+Drupal.progressBar.prototype.setProgress = function (percentage, message) {
+  if (percentage >= 0 && percentage <= 100) {
+    $('div.filled', this.element).css('width', percentage + '%');
+    $('div.percentage', this.element).html(percentage + '%');
+  }
+  $('div.message', this.element).html(message);
+  if (this.updateCallback) {
+    this.updateCallback(percentage, message, this);
+  }
+};
+
+/**
+ * Start monitoring progress via Ajax.
+ */
+Drupal.progressBar.prototype.startMonitoring = function (uri, delay) {
+  this.delay = delay;
+  this.uri = uri;
+  this.sendPing();
+};
+
+/**
+ * Stop monitoring progress via Ajax.
+ */
+Drupal.progressBar.prototype.stopMonitoring = function () {
+  clearTimeout(this.timer);
+  // This allows monitoring to be stopped from within the callback.
+  this.uri = null;
+};
+
+/**
+ * Request progress data from server.
+ */
+Drupal.progressBar.prototype.sendPing = function () {
+  if (this.timer) {
+    clearTimeout(this.timer);
+  }
+  if (this.uri) {
+    var pb = this;
+    // When doing a post request, you need non-null data. Otherwise a
+    // HTTP 411 or HTTP 406 (with Apache mod_security) error may result.
+    $.ajax({
+      type: this.method,
+      url: this.uri,
+      data: '',
+      dataType: 'json',
+      success: function (progress) {
+        // Display errors.
+        if (progress.status == 0) {
+          pb.displayError(progress.data);
+          return;
+        }
+        // Update display.
+        pb.setProgress(progress.percentage, progress.message);
+        // Schedule next timer.
+        pb.timer = setTimeout(function () { pb.sendPing(); }, pb.delay);
+      },
+      error: function (xmlhttp) {
+        pb.displayError(Drupal.ajaxError(xmlhttp, pb.uri));
+      }
+    });
+  }
+};
+
+/**
+ * Display errors on the page.
+ */
+Drupal.progressBar.prototype.displayError = function (string) {
+  var error = $('<div class="messages error"></div>').html(string);
+  $(this.element).before(error).hide();
+
+  if (this.errorCallback) {
+    this.errorCallback(this);
+  }
+};
+
+})(jQuery);