code: function(options) {
          if (typeof options.trigger === 'undefined') {
              return;
          }
  
          this.$container = $('<div style="display:none;"></div>');
          this.$container.addClass(defaultClass + ' ' + options.customClass)
              .appendTo('body')
              .append(this.$main.show());
  
          this.$trigger = $(options.trigger);
          var self = this;
          this.$trigger.on('click.bizDropDown', function() {
              self.toggle();
          });
      }
docs: 初始化
  @param {Object} options 参数
  @private