code: function() {
  
          if (!this.open) {
              return;
          }
  
          var anchor = this.anchor;
  
          if (typeof anchor === 'string') {
              anchor = this.anchor = document.querySelector(anchor);
          }
  
          this.node.style.position = this.options.fixed ? 'fixed' : 'absolute';
  
          if (anchor) {
              this.__anchor(anchor);
          } else {
              this.__center();
          }
  
          return this;
      }
docs: 重置位置