one-way data binding in Polymer

one-way-binding.html

<dom-module id="my-component">
  <template>
    <paper-toast text="[[greeting]]"></paper-toast>
  </template>

  <script>
    Polymer({
      is: 'my-component',

      properties: {
        greeting: {
          type: String,
          value: 'Hello'
        }
      }
    });
  </script>
</dom-module>