Hide last updated data until date is populated.

Tools/GardeningServer/ui/ct-last-updated.html

 <!--
 Copyright 2014 The Chromium Authors. All rights reserved.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 
 <polymer-element name="ct-last-updated" attributes="date">
   <template>
-    Updated {{ date | _deltaMinutes }} min ago @ {{ date | _hours }}:{{ date | _minutes }}
+    <style>
+      .hidden {
+        opacity: 0;
+      }
+    </style>
+    <span class="{{ { hidden: !visible } | tokenList }}">Updated {{ date | _deltaMinutes }} min ago @ {{ date | _hours }}:{{ date | _minutes }}</span>

[ojan, 2014/08/12 17:39:05]

I think your <template if> problem is likely that you put the if on the outer
template. You can only put template directives on nested templates. I just poked
the polymer team to make this more clear in their documentation.

[teravest, 2014/08/12 19:31:41]

I've changed this to use an inner template tag as well.

   </template>
   <script>
   (function() {
     Polymer({
       date: new Date(0),
+      visible: false,
+
+      dateChanged: function() {
+        this.visible = true;
+      },
 
       _deltaMinutes: function(date) {
         return date.minutesAgo();
       },
       _hours: function(date) {
         return date.getHours();
       },
       _minutes: function(date) {
         return date.getMinutes();
       },
     });
   })();
 
   </script>
 </polymer-element>