title: How to trigger event after rendering Polymer element?
body: <p>I'm implementing a search list element, but I have trouble showing the current count of search result. It is always showing the result of my previous step. Is there way to get the value (or trigger the event) after the DOM finished rendering?</p>
  
  <p>Here is the code:</p>
  
  <pre><code>//main
  &lt;template&gt;
    &lt;items-list
      items="{{items}}"
      search="{{search}}"&gt;
    &lt;/items-list&gt;
    count: {{count}}
  &lt;/template&gt;
  &lt;script&gt;
    Polymer({
      searchChanged: function () {
        this.count = this.shadowRoot.querySelector('items-list').getCount();
      }
    });
  &lt;/script&gt;
  
  //item-list
  &lt;polymer-element name="items-list" attributes="search items"&gt;
    &lt;template&gt;
      &lt;template repeat="{{item in items}}"&gt;
        &lt;item
          hidden?="{{toHide(search, item.name)}}"
          item="{{item}}"&gt;
        &lt;/item&gt;
      &lt;/template&gt;
    &lt;/template&gt;
  
    &lt;script&gt;
      Polymer({
        toHide: function (search, breedName) {
          //...
        },
  
        getCount: function () {
          var items = this.shadowRoot.querySelectorAll('item:not([hidden])');
  
          return items.length;
        }
      });
    &lt;/script&gt;
  &lt;/polymer-element&gt;
  </code></pre>