先上程式碼
.js

Page({
  /** 
   * 頁面的初始資料 
   */
  data: {
    isActive: null,
    listMain: [{
      id: "1", region: "A",
      items: [
        { id: "", name: "amour" },
        { id: "", name: "amour" },
        { id: "", name: "amour" },
        { id: "", name: "amour" }
      ]
    },
      {
        id: "2", region: "B",
        items: [
          { id: "", name: "bandon" },
          { id: "", name: "bandon" }
        ]
      },
      {
        id: "3", region: "C",
        items: [
          { id: "", name: "client" },
          { id: "", name: "client" },
          { id: "", name: "client" },
          { id: "", name: "client" }
        ]
      },
      {
        id: "4", region: "D",
        items: [
          { id: "", name: "digital" },
          { id: "", name: "digital" }
        ]
      },
      {
        id: "5", region: "E",
        items: [
          { id: "", name: "echo" },
          { id: "", name: "echo" },
          { id: "", name: "echo" },
          { id: "", name: "echo" }
        ]
      },
      {
        id: "6", region: "F",
        items: [
          { id: "", name: "funk" },
          { id: "", name: "funk" }
        ]
      },
      ],
    listTitles: [],
    fixedTitle: 'A',
    toView: 'inToView0',
    viewPosition: [],
    scroolHeight: 0
  },
    //頁面載入觸發， 獲取所定義view距離可滾動檢視區域頂部高度
  onLoad: function(options){
    var that = this ;
    var num = 0;
    for (let i = 0; i < that.data.listMain.length;i++){  
      wx.createSelectorQuery().select('#inToView' + that.data.listMain[i].id).boundingClientRect(function(rect){
        num = num + rect.height; //元素高度+該元素先前元素高度 ， 可理解為元素底部至可滾動檢視區域頂部高度
        console.log(num)
        var _array = [{ 'height': num, 'key': rect.dataset.id , 'name':that.data.listMain[i].region}];
        that.setData ({
          viewPosition: that.data.viewPosition.concat(_array) //合併陣列
        });  
      }).exec()
    };  
  }，
  // 可滾動檢視區域滑動函式觸發
  onPageScroll: function (e) {
    console.log(e)
    this.setData({
      scroolHeight: e.detail.scrollTop //獲取滾動條滾動位置
    });
    for (let i in this.data.viewPosition) {
      if (e.detail.scrollTop < this.data.viewPosition[i].height) { //判斷滾動條位置是否在元素內
        this.setData({
          isActive: this.data.viewPosition[i].key,
          fixedTitle: this.data.viewPosition[i].name
        });
        return false;
      }
    }
  },
    //點選右側字母導航定位觸發
  scrollToViewFn: function (e) {
    console.log(e)
    var that = this;
    var _id = e.target.dataset.id;
    for (var i = 0; i < that.data.listMain.length; ++i) {
      if (that.data.listMain[i].id === _id) {
        that.setData({
          isActive: _id,
          toView: 'inToView' + _id //滾動條to指定view
        })
        break
      }
    }
  },
}) 
 

知識點 ：
1、wx.createSelectorQuery() ：返回一個SelectorQuery物件例項。可以在這個例項上使用select等方法選擇節點，並使用boundingClientRect等方法選擇需要查詢的資訊。 利用boundingClientRect函式返回height屬性值
2. scrollTop 獲得可滾動檢視區域豎向滾動條位置
3. .wxml用scrool-view元件 ， scroll-with-animation=“true” 在設定滾動條位置時使用動畫過渡 ； scroll-y=“true"允許縱向滾動 ； scroll-into-view=”{{toView}}"值應為某子元素id（id不能以數字開頭），設定哪個方向可滾動，則在哪個方向滾動到該元素。
4. 沒了 ， 小程式來實現這種效果還是很方便的
.wxml

<view >
<!-- 左側列表內容部分 -->
  <scroll-view class="content" enable-back-to-top scroll-into-view="{{toView}}" scroll-y="true" scroll-with-animation="true" bindscroll="onPageScroll"> 
    <view wx:for="{{listMain}}" wx:for-item="group" wx:key="{{group.id}}"  id="{{ 'inToView'+group.id}}" data-id='{{group.id}}'> 
      <view class="address_top" >{{group.region}}</view> 
        <view wx:for="{{group.items}}" wx:for-item="item" wx:key="{{item.brandId}}"> 
          <view class="address_bottom" data-id='{{item.brandId}}'>{{item.name}}</view> 
        </view> 
    </view> 
  </scroll-view> 
  <!-- 頂部固定分類 -->
  <view class="list-fixed {{fixedTitle=='' ? 'hide':''}}" style="transform:translate3d(0,{{fixedTop}}px,0);">
    <view class="fixed-title">
    {{fixedTitle}}
    </view>
  </view>
  <!-- 右側字母導航 -->
  <view class="orientation_region"> 
    <view class="orientation">自動定位</view> 
      <block wx:for="{{listMain}}"  wx:key="{{item.id}}"> 
        <view class="orientation_city  {{isActive==item.id ? 'active':'' }}" bindtap="scrollToViewFn" data-id="{{item.id}}" >
        {{item.region}}
        </view> 
    </block> 
  </view>  
</view> 
 

.wxss

page{ height: 100%;} 
.content{padding-bottom: 20rpx; box-sizing: border-box; height: 100%;position: fixed} 
.location{width: 100%;} 
.location_top{height: 76rpx;line-height: 76rpx; background: #f4f4f4;color: #606660;font-size: 28rpx;padding: 0 20rpx;} 
.location_bottom{height: 140rpx;line-height: 140rpx;color: #d91f16;font-size: 28rpx;border-top: 2rpx #ebebeb solid; border-bottom: 2rpx #ebebeb solid;padding: 0 20rpx; align-items: center;display: -webkit-flex;} 
.address_top{height: 56rpx;line-height: 56rpx; background: #EBEBEB;color: #999999;font-size: 28rpx;padding: 0 20rpx;} 
.address_bottom{height: 88rpx;line-height: 88rpx; background: #fff;color: #000000;font-size: 32rpx;padding: 0 20rpx; border-bottom: 2rpx #ebebeb solid;margin-left: 20rpx;margin-right: 50rpx; } 
.location_img{width: 48rpx;height: 48rpx;position: absolute;right: 20rpx;top: 125rpx;} 
.add_city{width: 228rpx;height: 60rpx;line-height: 60rpx; text-align: center; border: 2rpx solid #ebebeb; color: #000000;margin-right: 20rpx; } 
.add_citying{width: 228rpx;height: 60rpx;line-height: 60rpx; text-align: center; border: 2rpx solid #09bb07; color: #09bb07;margin-right: 20rpx;} 
.orientation{white-space:normal;display: inline-block; width: 55rpx;height:58rpx; color: #999; text-align: center;} 
.orientation_region{ width: 55rpx;font-size: 20rpx;position: fixed;top: 100rpx; right: 0rpx;} 
.orientation_city{height: 40rpx; line-height: 40rpx;color: #000;text-align: center;} 
.active{color: #2cc1d1;}
.list-fixed{position: fixed;width: 100%;z-index: 999; height: 56rpx;line-height: 56rpx; background: #EBEBEB;color: #999999;font-size: 28rpx;padding: 0 20rpx;z-index: 9999;}