px-demo-behaviors.html

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<script>
var PxDemoBehaviors = PxDemoBehaviors || {};

/*
  Name:
  PxDemoBehaviors.manageProps

  Description:
  Common methods for dealing with props.

  @polymerBehavior PxDemoBehaviors.manageProps
*/
PxDemoBehaviors.manageProps = [{
  /**
   * On first run, copy each prop's `defaultValue` to its `value`. If you
   * need to add props dynamically, you can call this method manually on the
   * `px-demo-props` instance. Passing `overwriteValue` as `true` will reset
   * the props to their default value.
   *
   * @method applyPropDefaults
   * @param {Boolean} overwriteValue - If `true`, will write the default to value even if the value is already defined
   * @return null
   */
  applyPropDefaults: function(overwriteValue) {
    overwriteValue = overwriteValue || false;
    var props = this.props;
    var propKeys = Object.keys(this.props);

    for (var i = 0; i < propKeys.length; i++) {
      var prop = props[propKeys[i]];
      var pathTo = function(key) { return 'props.' + propKeys[i] + '.' + key; };
      var defaultValue = this.get(pathTo('defaultValue'));
      var value = this.get(pathTo('value'));

      if ((typeof defaultValue !== 'undefined') && ((typeof value === 'undefined') || overwriteValue)) {
        this.set(pathTo('value'), defaultValue);
      }
    }
  }
}];
</script>