var params = res.data.data;
        var cityList = []
        //        城市列表
        // [{index:A,list:[{cityId:"",cityName:""},{cityId:"",cityName:""},{cityId:"",cityName:""}]}] []*/

        for (var i = 0; i < params.length; i++) {
          var letterFirst = params[i].pinyin.substr(0, 1).toUpperCase();
          if (isCityList(letterFirst)) {
            for (var k = 0; k < cityList.length; k++) {
              if (letterFirst == cityList[k].index) {
                cityList[k].list.push({
                  cityId: params[i].id,
                  cityName: params[i].name,
                  latitude: params[i].latitude,
                  longitude: params[i].longitude,
                });
                break;
              }
            }
          } else {
            cityList.push({
              index: letterFirst,
              list: [{
                cityId: params[i].id,
                cityName: params[i].name,
                latitude: params[i].latitude,
                longitude: params[i].longitude,
              }]
            })
          }
        }
 //判断当前标识是否在cityList当中
        function isCityList(letterFirst) {
          var bStop = false;
          for (var i = 0; i < cityList.length; i++) {
            if (cityList[i].index == letterFirst) {
              bStop = true;
              break;
            }
          }

          return bStop; //存在为true 不存在未false
        }
        //     //排序
        cityList.sort((item1, item2) => {
          if (item1.index > item2.index) {
            return 1;
          } else {
            return -1;
          }
        })

<scroll-view scroll-y="true" style="height:100%;" scroll-into-view="{{scrollTopId}}" scroll-with-animation="true" enable-back-to-top="true">
      ...
      <text >{{item.index}}</text>
      ...
</scroll-view>

  selectChooseHandler(e) {
    this.setData({
      scrollTopId: e.target.id,
    })
  },