code: function(anchor) {
  
          if (this.destroyed) {
              return this;
          }
  
          var node = this.node;
  
          this.__activeElement = getActiveElement();
  
          this.open = true;
          this.anchor = anchor;
  
  
          addClass(node, this.options.className);
          addClass(node, this.__name('show'));
          node.setAttribute('role', this.modal ? 'alertdialog' : 'dialog');
  
  
          if (!this.__show) {
              this.focus = this.focus.bind(this);
              this.reset = this.reset.bind(this);
              this.__show = true;
          }
  
  
          // 模态浮层的遮罩
          if (this.modal) {
  
              addClass(node, this.__name('modal'));
  
              // 让焦点限制在浮层内
              addEvent(document, 'focusin', this.focus);
          }
  
  
          this.options.showElement(node);
  
  
          addEvent(window, 'resize', this.reset);
  
          this.reset().focus();
  
          return this;
      }
docs: 显示浮层
  @param   {HTMLElement, Event}  指定位置（可选）