code: function() {
              var self = this;
              self.plus.addEventListener(tapEventName, function(event) {
                  var val = parseInt(self.input.value) + self.options.step;
                  self.input.value = val.toString();
                  $.trigger(self.input, changeEventName, null);
              });
              self.minus.addEventListener(tapEventName, function(event) {
                  var val = parseInt(self.input.value) - self.options.step;
                  self.input.value = val.toString();
                  $.trigger(self.input, changeEventName, null);
              });
              self.input.addEventListener(changeEventName, function(event) {
                  self.checkValue();
                  var val = parseInt(self.input.value);
                  //触发顶层容器
                  $.trigger(self.holder, changeEventName, {
                      value: val
                  });
              });
          }
docs: 初始化事件绑定