Update to Drupal 8.0.0 beta 14. For more information, see https://drupal.org/node/2544542

core/misc/date.js

@@ -0,0 +1,56 @@
+/**
+ * @file
+ * Polyfill for HTML5 date input.
+ */
+
+(function ($, Modernizr, Drupal) {
+
+  "use strict";
+
+  /**
+   * Attach datepicker fallback on date elements.
+   *
+   * @type {Drupal~behavior}
+   *
+   * @prop {Drupal~behaviorAttach} attach
+   *   Attaches the behavior. Accepts in `settings.date` an object listing
+   *   elements to process, keyed by the HTML ID of the form element containing
+   *   the human-readable value. Each element is an datepicker settings object.
+   * @prop {Drupal~behaviorDetach} detach
+   *   Detach the behavior destroying datepickers on effected elements.
+   */
+  Drupal.behaviors.date = {
+    attach: function (context, settings) {
+      var $context = $(context);
+      // Skip if date are supported by the browser.
+      if (Modernizr.inputtypes.date === true) {
+        return;
+      }
+      $context.find('input[data-drupal-date-format]').once('datePicker').each(function () {
+        var $input = $(this);
+        var datepickerSettings = {};
+        var dateFormat = $input.data('drupalDateFormat');
+        // The date format is saved in PHP style, we need to convert to jQuery
+        // datepicker.
+        datepickerSettings.dateFormat = dateFormat
+          .replace('Y', 'yy')
+          .replace('m', 'mm')
+          .replace('d', 'dd');
+        // Add min and max date if set on the input.
+        if ($input.attr('min')) {
+          datepickerSettings.minDate = $input.attr('min');
+        }
+        if ($input.attr('max')) {
+          datepickerSettings.maxDate = $input.attr('max');
+        }
+        $input.datepicker(datepickerSettings);
+      });
+    },
+    detach: function (context, settings, trigger) {
+      if (trigger === 'unload') {
+        $(context).find('input[data-drupal-date-format]').findOnce('datePicker').datepicker('destroy');
+      }
+    }
+  };
+
+})(jQuery, Modernizr, Drupal);