code: function() {
  
          var node = this.node;
          var current = Popup.current;
          var index = this.zIndex = Popup.zIndex++;
  
          if (current && current !== this) {
              current.blur(false);
          }
  
          // 检查焦点是否在浮层里面
          if (!node.contains(getActiveElement())) {
              var autofocus = node.querySelector('[autofocus]');
  
              if (!this.__autofocus && autofocus) {
                  this.__autofocus = true;
              } else {
                  autofocus = node;
              }
  
              this.__focus(autofocus);
          }
  
          // 设置叠加高度
          node.style.zIndex = index;
  
  
          Popup.current = this;
          addClass(node, this.__name('focus'));
  
          return this;
      }
docs: 让浮层获取焦点