code: function(options) {
          // 在 body 下创建抽屉浮层和遮罩层
          this.$container = $('<div style="display:none;"></div>');
          this.$mask = $('<div class="biz-mask" style="display:none;"></div>');
          this.$container.appendTo('body').after(this.$mask);
  
          // 填充 $container
          var self = this;
          this.$container.addClass([defaultClass, options.customClass, prefix + options.theme].join(' '))
              .html([
                  '<div class="biz-panel-margin"></div>',
                  '<div class="biz-panel-body">',
                  '<div class="biz-panel-title">',
                  '<span class="biz-panel-title-text">', this.$main.attr('data-title') || options.title, '</span>',
                  '<i class="biz-panel-close biz-icon">&#xe5cd;</i></div>',
                  '<div class="biz-panel-content"></div>',
                  '<div class="biz-panel-bottom"></div></div>'
              ].join(''))
              .on('click.bizPanel', '.biz-panel-close', function() {
                  self.close();
              });
          this.$container.find('.biz-panel-content').append(this.$main.show()); // 把目标元素移至 $container 中
          this.updateButtons(options.buttons);
  
          this.$container.find('.biz-panel-margin').css({
              width: options.marginLeft
          });
      }
docs: 初始化
  @param {Object} options 参数
  @private