behavior singleton model

exampleBehavior.html

<script>
  // Resolve / declare namespace
  window.MyCustomBehaviors = window.MyCustomBehaviors || {};

  // This is a globally shared connection.
  var singletonConnection = null;

  window.MyCustomBehaviors.SocketConnectionBehavior = {
    properties: {
      connection: {
        type: Object,
        value: function () {
          return getConnection();
        }
      }
    },
    // This function returns the global connection and creates an instance of it if necessary.
    getConnection: function () {
      if (singletonConnection === null) {
        // Shared instance is created and assigned here
        singletonConnection = new SocketConnection();
      }
      return singletonConnection;
    }
  };

  window.MyCustomBehaviors.MyCustomInheritedBehavior = [
    Polymer.NeonSharedElementAnimatableBehavior, // just an example
    window.MyCustomBehaviors.SocketConnectionBehavior
  ];
</script>