data-array-selector.html

<dom-module id="data-array-selector">
  <template>
    <style>:host { display: none; }</style>
  </template>
  <script>
  (function() {
    Polymer({
      is: 'data-array-selector',

      properties: {
        items: {
          type: Array
        },

        selectedIndex: {
          type: Number
        },

        _lastIndex: {
          type: Number
        },

        selected: {
          type: Object,
          notify: true
        }
      },

      observers: [
        '_computeSelectedItem(items, selectedIndex)'
      ],

      _computeSelectedItem: function(items, selectedIndex) {
        this.unlinkPaths('selected');
        this.selected = items[selectedIndex];
        this.linkPaths('selected', 'items.#' + selectedIndex);
      }
    });
  }());
  </script>
</dom-module>