--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cms/drupal/misc/timezone.js	Fri Sep 08 12:04:06 2017 +0200
@@ -0,0 +1,66 @@
+(function ($) {
+
+/**
+ * Set the client's system time zone as default values of form fields.
+ */
+Drupal.behaviors.setTimezone = {
+  attach: function (context, settings) {
+    $('select.timezone-detect', context).once('timezone', function () {
+      var dateString = Date();
+      // In some client environments, date strings include a time zone
+      // abbreviation, between 3 and 5 letters enclosed in parentheses,
+      // which can be interpreted by PHP.
+      var matches = dateString.match(/\(([A-Z]{3,5})\)/);
+      var abbreviation = matches ? matches[1] : 0;
+
+      // For all other client environments, the abbreviation is set to "0"
+      // and the current offset from UTC and daylight saving time status are
+      // used to guess the time zone.
+      var dateNow = new Date();
+      var offsetNow = dateNow.getTimezoneOffset() * -60;
+
+      // Use January 1 and July 1 as test dates for determining daylight
+      // saving time status by comparing their offsets.
+      var dateJan = new Date(dateNow.getFullYear(), 0, 1, 12, 0, 0, 0);
+      var dateJul = new Date(dateNow.getFullYear(), 6, 1, 12, 0, 0, 0);
+      var offsetJan = dateJan.getTimezoneOffset() * -60;
+      var offsetJul = dateJul.getTimezoneOffset() * -60;
+
+      var isDaylightSavingTime;
+      // If the offset from UTC is identical on January 1 and July 1,
+      // assume daylight saving time is not used in this time zone.
+      if (offsetJan == offsetJul) {
+        isDaylightSavingTime = '';
+      }
+      // If the maximum annual offset is equivalent to the current offset,
+      // assume daylight saving time is in effect.
+      else if (Math.max(offsetJan, offsetJul) == offsetNow) {
+        isDaylightSavingTime = 1;
+      }
+      // Otherwise, assume daylight saving time is not in effect.
+      else {
+        isDaylightSavingTime = 0;
+      }
+
+      // Submit request to the system/timezone callback and set the form field
+      // to the response time zone. The client date is passed to the callback
+      // for debugging purposes. Submit a synchronous request to avoid database
+      // errors associated with concurrent requests during install.
+      var path = 'system/timezone/' + abbreviation + '/' + offsetNow + '/' + isDaylightSavingTime;
+      var element = this;
+      $.ajax({
+        async: false,
+        url: settings.basePath,
+        data: { q: path, date: dateString },
+        dataType: 'json',
+        success: function (data) {
+          if (data) {
+            $(element).val(data);
+          }
+        }
+      });
+    });
+  }
+};
+
+})(jQuery);