code: function(anchor) {
  
          if (this.destroyed) {
              return this;
          }
  
          var that = this;
          var popup = this.__popup;
          var backdrop = this.__backdrop;
  
          this.__activeElement = this.__getActive();
  
          this.open = true;
          this.follow = anchor || this.follow;
  
  
          // 初始化 show 方法
          if (!this.__ready) {
  
              popup
                  .addClass(this.className)
                  .attr('role', this.modal ? 'alertdialog' : 'dialog')
                  .css('position', this.fixed ? 'fixed' : 'absolute');
  
              if (!_isIE6) {
                  $(window).on('resize', $.proxy(this.reset, this));
              }
  
              // 模态浮层的遮罩
              if (this.modal) {
                  var backdropCss = {
                      position: 'fixed',
                      left: 0,
                      top: 0,
                      width: '100%',
                      height: '100%',
                      overflow: 'hidden',
                      userSelect: 'none',
                      zIndex: this.zIndex || Popup.zIndex
                  };
  
  
                  popup.addClass(this.className + '-modal');
  
  
                  if (!_isFixed) {
                      $.extend(backdropCss, {
                          position: 'absolute',
                          width: $(window).width() + 'px',
                          height: $(document).height() + 'px'
                      });
                  }
  
  
                  backdrop
                      .css(backdropCss)
                      .attr({ tabindex: '0' })
                      .on('focus', $.proxy(this.focus, this));
  
                  // 锁定 tab 的焦点操作
                  this.__mask = backdrop
                      .clone(true)
                      .attr('style', '')
                      .insertAfter(popup);
  
                  backdrop
                      .addClass(this.className + '-backdrop')
                      .insertBefore(popup);
  
                  this.__ready = true;
              }
  
  
              if (!popup.html()) {
                  popup.html(this.innerHTML);
              }
          }
  
  
          popup
              .addClass(this.className + '-show')
              .show();
  
          backdrop.show();
  
  
          this.reset().focus();
          this.__dispatchEvent('show');
  
          return this;
      }
docs: 显示浮层
  @param   {HTMLElement, Event}  指定位置（可选）