gistfile1.html

<!-- Define element -->
<polymer-element name="my-counter" attributes="counter">
  <template>
    <style> /*...*/ </style>
    <div id="label"><content></content></div>
    Value: <span id="counterVal">{{counter}}</span><br>
    <button on-tap="{{increment}}">Increment</button>
  </template>
  <script>
    Polymer({
      counter: 0, // Default value
      counterChanged: function() {
        this.$.counterVal.classList.add('highlight');
      },
      increment: function() {
        this.counter++;
      }
    });
  </script>
</polymer-element>

<!-- Use element -->
<my-counter counter="10">Points</my-counter>