【微信小程式】手寫索引選擇器（城市列表，汽車品牌選擇列表）

摘要： 小程式索引選擇器，點擊跳轉相應條目，索引可滑動，滑動也可跳轉

場景：城市選擇列表， 汽車品牌選擇列表

所用組件： scroll-view（小程式原生） https://developers.weixin.qq.com/miniprogram/dev/component/scroll-view.html

  1 list: [
  2             {
  3               "letter": "A",
  4               "list": [{
  5                 "name": "奧迪1",
  6                 "id": 1
  7               },
  8               {
  9                 "name": "奧迪2",
 10                 "id": 2
 11               }]
 12             },
 13             {
 14               "letter": "B",
 15               "list": [{
 16                 "name": "寶馬1",
 17                 "id": 3
 18               },
 19               {
 20                 "name": "寶馬2",
 21                 "id": 4
 22               }]
 23             },
 24             {
 25               "letter": "C",
 26               "list": [{
 27                 "name": "麻喇沙底",
 28                 "id": 5
 29               },
 30               {
 31                 "name": "adidas",
 32                 "id": 6
 33               }]
 34             },
 35             {
 36               "letter": "D",
 37               "list": [{
 38                 "name": "煲事件",
 39                 "id": 7
 40               },
 41               {
 42                 "name": "保時捷",
 43                 "id": 8
 44               }]
 45             },
 46             {
 47               "letter": "E",
 48               "list": [{
 49                 "name": "寶馬1",
 50                 "id": 9
 51               },
 52               {
 53                 "name": "寶馬2",
 54                 "id": 10
 55               }]
 56             },
 57             {
 58               "letter": "F",
 59               "list": [{
 60                 "name": "寶馬1",
 61                 "id": 11
 62               },
 63               {
 64                 "name": "寶馬2",
 65                 "id": 12
 66               }]
 67             },
 68             {
 69               "letter": "G",
 70               "list": [{
 71                 "name": "寶馬1",
 72                 "id": 15
 73               },
 74               {
 75                 "name": "寶馬2",
 76                 "id": 16
 77               }]
 78             },
 79             {
 80               "letter": "H",
 81               "list": [{
 82                 "name": "寶馬1",
 83                 "id": 17
 84               },
 85               {
 86                 "name": "寶馬2",
 87                 "id": 18
 88               }]
 89             },
 90             {
 91               "letter": "I",
 92               "list": [{
 93                 "name": "寶馬1",
 94                 "id": 19
 95               },
 96               {
 97                 "name": "寶馬2",
 98                 "id": 20
 99               }]
100             },
101             {
102               "letter": "J",
103               "list": [{
104                 "name": "寶馬1",
105                 "id": 21
106               },
107               {
108                 "name": "寶馬2",
109                 "id": 22
110               }]
111             },
112             {
113               "letter": "K",
114               "list": [{
115                 "name": "寶馬1",
116                 "id": 23
117               },
118               {
119                 "name": "寶馬2",
120                 "id": 24
121               }]
122             },
123           ]

 html 結構：

主體部分

 1 <scroll-view class="content" scroll-y="true" :style="scrollHeight" :scroll-top="scrollData.scrollTop" :scroll-into-view="toView">
 2       <ul class="brandList">
 3         <li v-for="(item, index) in list" :key="index" :id="item.letter">
 4           <h2>{{item.letter}}</h2>
 5           <div v-for="(el, i) in item.list" :key="i" class="pro" @click="getToast(el.name)">
 6             <img src="/static/images/user.png" alt="" mode="aspectFit">
 7             <span>{{el.name}}</span>
 8           </div>
 9         </li>
10       </ul>
11     </scroll-view>

1 // 側邊導航欄
2 <div class="letterList" @touchstart="handlerTouchMove" 
3         @touchmove="handlerTouchMove" 
4         @touchend="handlerTouchEnd" :style="fixedTop">
5       <p v-for="(item, index) in list" :key="index" @click="getLetter(item.letter)">{{item.letter}}</p>
6     </div>

scrollData: {
        scrollTop: 0,
      },
      toView:'A',

step1： 

首先，側邊導航欄肯定是用fixed定位固定（一般在右側），其次在豎直方向居中，調用wx.getSystemInfo 

1 let fixedTop = 0;
2       let length = this.list.length // 取到list數組的length，因為list的length決定了側邊導航的高度
3       wx.getSystemInfo({
4         success(res) {
5           fixedTop = (res.windowHeight - (20 * length))/2  //20為側邊導航每個p的高度
6         }
7       })

step2

手指在側邊導航滑動時的js

 1 handlerTouchMove (e) {
 2       let touches = e.touches[0] || {}
 3       let pageY = touches.pageY
 4       let rest = pageY - this.fixedTop
 5       let index = Math.ceil(rest / 20)
 6       console.log(this.list.length, index, 206);
 7       console.log(index,195);
 8       if(index > this.list.length) {
 9         index = this.list.length - 1// 
10       }
11       if( 0 <index <= this.list.length) { // 1213  10  9
12         index = index - 1
13       }
14       if(index <= 0) {
15         index = 0
16       }
17       let letter = this.list[index].letter
18       wx.showToast({
19         title: letter,
20         icon: 'none',
21         duration: 2000
22       })
23       this.toView = letter
24     },
25     handlerTouchEnd () {
26       wx.hideLoading()
27     },

step3

點擊側邊索引時的js

1     getLetter (letter) {
2       this.toView = letter
3     },

結束惹，88， 下次見

是