code: function ForItemData(forElement, item, index) {
      this.parent = forElement.scope;
      this.raw = {};
      this.listeners = [];
  
      this.directive = forElement.aNode.directives['for']; // eslint-disable-line dot-notation
      this.indexName = this.directive.index || '$index';
  
      this.raw[this.directive.item] = item;
      this.raw[this.indexName] = index;
  }
docs: 循环项的数据容器类
  
  @inner
  @class
  @param {Object} forElement for元素对象
  @param {*} item 当前项的数据
  @param {number} index 当前项的索引