<view class="right-nav">
 <view bindtap="getCurrentCode" class="{{chooseIndex == index " wx:for="{{cityList}}" style="height:{{codeHeight}}px" data-code="{{item.code}}">
 {{item.code}}
 </view>
</view>

<view class="city-layer {{isShowLayer ">
 {[code]}
</view>

<view class="current-choose-city">当前选择机场：{{chooseCity}}</view>
<scroll-view class="city-scroll" scroll-y="true" style="height:{{cityHeight}}px" bindscroll="scroll" scroll-top="{{scrollTop}}">
 <view class="city-box" wx:for="{{cityList}}" wx:key="{{item.code}}">
  <view class="city-code">{{item.code}}</view>
  <view class="city-list" wx:for="{{item.cityList}}" wx:for-item="city" bindtap="getChooseCity" data-city="{{city}}"> 
    {{city}} 
  </view> 
 </view>
</scroll-view>

.current-choose-city{
 position: fixed;
 width: 100%;
 height: 50px;
 line-height: 50px;
 padding: 0 10px;
 top: 0;
 left: 0;
 background-color: #fff;
 z-index: 10;
}
.right-nav{
 width: 30px;
 color: #888;
 text-align: center;
 position: fixed;
 bottom: 0;
 right: 0;
 background-color: rgb(200, 200, 200);
 z-index: 9;
}
.city-scroll{padding-top: 50px;}
.city-code{
 background-color: #f7f7f7;
}
.city-list,.city-code{
 height: 39px;
 line-height: 40px;
 padding: 0 30px 0 10px;
 overflow: hidden;
 border-bottom: 1px solid #c8c7cc;
}
.city-list-active{color:#007aff;}

/*提示点击的字母 */
.city-layer{
 width: 70px;
 height: 70px;
 line-height: 70px;
 text-align: center;
 border-radius: 50%;
 color: #fff;
 background-color: rgba(0, 0, 0, .7);
 position: fixed;
 top: calc(50% - 35px);
 left:calc(50% - 35px);
 z-index: 11;
}
.layer-hide{display: none;}

var city_list = require('./city.js');

Page({
 data: {
 cityList: city_list.city,
 chooseCity: '您还未选择机场！',
 isShowLayer: false,
 chooseIndex: 0,
 len: [],
 code: null,
 codeHeight: null,
 cityHeight:null,
 scrollTop: 0
 },
 onLoad (options) {
 var windowHeight = wx.getSystemInfoSync().windowHeight;
 var arr = [];

 this.data.cityList.forEach(current => arr.push(current.cityList.length + 1));
 this.setData({ 
  codeHeight: (windowHeight - 50) / this.data.cityList.length,
  cityHeight: windowHeight - 50,
  len: arr
 });
 },
 getCurrentCode(e){
 var index = 0, sum = 0,self = this;

 for (var i = 0; i < this.data.cityList.length;i++){
  if (this.data.cityList[i].code === e.target.dataset.code){
  index = i
  break;
  }
 }
 for (var j = 0; j < index; j++) {
  sum += this.data.len[j];
 }

 this.setData({ 
  code: e.target.dataset.code,
  scrollTop: sum * 40,
  chooseIndex: index,
  isShowLayer: true  
 });

 setTimeout(() => {
  self.setData({ isShowLayer: false })
 },500);
 },
 getChooseCity(e){
 this.setData({ chooseCity: e.target.dataset.city });
 }
})

var index = 0;
for (var i = 0; i < this.data.cityList.length;i++){
 if (this.data.cityList[i].code === e.target.dataset.code){
 index = i
 break;
 }
}