vue中自定義IndexBar 索引欄

vant是一款基於vue的牛皮移動端組件庫，比如類似手機電話簿的字母索引蘭組件

https://youzan.github.io/vant/#/zh-CN/index-bar

今天看了朋友分享的一個自定義索引蘭組件代碼，是慕課網幾年前的某個vue教程，結合vant的indexBar源碼，值得一看學習學習

 

 

父組件

    <list-view @select="selectSinger" :data="singers" ref="list"></list-view>

子組件

<template>
  <!-- 右側字母樣式  索引欄 子組件 -->
  <scroll @scroll="scroll"
          :listen-scroll="listenScroll"
          :probe-type="probeType"
          :data="data"
          class="listview"
          ref="listview">
    <!-- 左側內容列表 -->
    <ul>
      <li v-for="group in data" :key="group" class="list-group" ref="listGroup">
        <!-- 子分類標題（‘熱’、字母） -->
        <h2 class="list-group-title">{{group.title}}</h2>
        <!-- 子分類列表 -->
        <uL>
          <li @click="selectItem(item)" v-for="item in group.items" 
           :key="item" class="list-group-item">
            <img class="avatar" v-lazy="item.avatar">
            <span class="name">{{item.name}}</span>
          </li>
        </uL>
      </li>
    </ul>

    <!-- 右側字母快速導航條 -->
    <div class="list-shortcut" @touchstart.stop.prevent="onShortcutTouchStart" @touchmove.stop.prevent="onShortcutTouchMove"
         @touchend.stop>
      <ul>
        <li v-for="(item, index) in shortcutList" :data-index="index" :key="index"
        class="item" :class="{'current':currentIndex===index}">{{item}}
        </li>
      </ul>
    </div>

    <!-- 頂部標題欄（顯示當前子分類所屬字母）  -->
    <div class="list-fixed" ref="fixed" v-show="fixedTitle">
      <div class="fixed-title">{{fixedTitle}} </div>
    </div>

    <!-- 封裝的加載狀態子組件 -->
    <div v-show="!data.length" class="loading-container">
      <loading></loading>
    </div>
  </scroll>
</template>

<script type="text/ecmascript-6">
  import Scroll from 'base/scroll/scroll'
  import Loading from 'base/loading/loading'
  import {getData} from 'common/js/dom'

  // 頂部標題欄高度
  const TITLE_HEIGHT = 30
  // 右側每個字母高度
  const ANCHOR_HEIGHT = 18

  export default {
    props: {
      data: {
        type: Array,
        default: []
      }
    },
    computed: {
      shortcutList() {
        return this.data.map((group) => {
          return group.title.substr(0, 1)
        })
      },

      //左側列表頁每個子列表滾動到頂部時，頂部標題欄顯示當前字母
      fixedTitle() {
        if (this.scrollY > 0) {
          return ''
        }
        return this.data[this.currentIndex] ? this.data[this.currentIndex].title : ''
      }
    },
    data() {
      return {
        scrollY: -1,
        currentIndex: 0,
        diff: -1
      }
    },
    created() {
      this.probeType = 3
      this.listenScroll = true
      this.touch = {}
      this.listHeight = []
    },
    methods: {
      selectItem(item) {
        this.$emit('select', item)
      },
            //右側快捷欄點擊事件
      onShortcutTouchStart(e) {
        let anchorIndex = getData(e.target, 'index')
        let firstTouch = e.touches[0]
        this.touch.y1 = firstTouch.pageY
        this.touch.anchorIndex = anchorIndex

        this._scrollTo(anchorIndex)
      },
            //右側快捷欄滑動事件
      onShortcutTouchMove(e) {
        let firstTouch = e.touches[0]
        this.touch.y2 = firstTouch.pageY
        let delta = (this.touch.y2 - this.touch.y1) / ANCHOR_HEIGHT | 0
        let anchorIndex = parseInt(this.touch.anchorIndex) + delta

        this._scrollTo(anchorIndex)
      },
      refresh() {
        this.$refs.listview.refresh()
      },
      scroll(pos) {
        this.scrollY = pos.y
      },
      _calculateHeight() {
        this.listHeight = []
        const list = this.$refs.listGroup
        let height = 0
        this.listHeight.push(height)
        for (let i = 0; i < list.length; i++) {
          let item = list[i]
          height += item.clientHeight
          this.listHeight.push(height)
        }
      },
      _scrollTo(index) {
        if (!index && index !== 0) {
          return
        }
        if (index < 0) {
          index = 0
        } else if (index > this.listHeight.length - 2) {
          index = this.listHeight.length - 2
        }
        this.scrollY = -this.listHeight[index]
        this.$refs.listview.scrollToElement(this.$refs.listGroup[index], 0)
      }
    },
    watch: {
      data() {
        setTimeout(() => {
          this._calculateHeight()
        }, 20)
      },

      //監聽Y軸方向滾動
      scrollY(newY) {
        const listHeight = this.listHeight
        // 當滾動到頂部，newY>0
        if (newY > 0) {
          this.currentIndex = 0
          return
        }
        // 在中間部分滾動
        for (let i = 0; i < listHeight.length - 1; i++) {
          let height1 = listHeight[i]
          let height2 = listHeight[i + 1]
          if (-newY >= height1 && -newY < height2) {
            this.currentIndex = i
            this.diff = height2 + newY
            return
          }
        }
        // 當滾動到底部，且-newY大於最后一個元素的上限
        this.currentIndex = listHeight.length - 2
      },
      
      //左側內容區，子分類的標題向上滾動到頂部標題欄位置時，取代原來的頂部標題欄內容
      // 為了提升用戶體驗，原來的頂部標題欄添加向上滑動的動畫效果
      // 此時需要判斷子分類的標題的scrollY值（即height2 + newY）是否小於頂部標題欄的高度TITLE_HEIGHT
      diff(newVal) {
        let fixedTop = (newVal > 0 && newVal < TITLE_HEIGHT) ? newVal - TITLE_HEIGHT : 0
        if (this.fixedTop === fixedTop) {
          return
        }
        this.fixedTop = fixedTop
        this.$refs.fixed.style.transform = `translate3d(0,${fixedTop}px,0)`
      }
    },
    components: {
      Scroll,
      Loading
    }
  }

</script>

<style scoped lang="stylus" rel="stylesheet/stylus">
  @import "~common/stylus/variable"

  .listview
    position: relative
    width: 100%
    height: 100%
    overflow: hidden
    background: $color-background
    .list-group
      padding-bottom: 30px
      .list-group-title
        height: 30px
        line-height: 30px
        padding-left: 20px
        font-size: $font-size-small
        color: $color-text-l
        background: $color-highlight-background
      .list-group-item
        display: flex
        align-items: center
        padding: 20px 0 0 30px
        .avatar
          width: 50px
          height: 50px
          border-radius: 50%
        .name
          margin-left: 20px
          color: $color-text-l
          font-size: $font-size-medium
    .list-shortcut
      position: absolute
      z-index: 30
      right: 0
      top: 50%
      transform: translateY(-50%)
      width: 20px
      padding: 20px 0
      border-radius: 10px
      text-align: center
      background: $color-background-d
      font-family: Helvetica
      .item
        padding: 3px
        line-height: 1
        color: $color-text-l
        font-size: $font-size-small
        &.current
          color: $color-theme
    .list-fixed
      position: absolute
      top: 0
      left: 0
      width: 100%
      .fixed-title
        height: 30px
        line-height: 30px
        padding-left: 20px
        font-size: $font-size-small
        color: $color-text-l
        background: $color-highlight-background
    .loading-container
      position: absolute
      width: 100%
      top: 50%
      transform: translateY(-50%)
</style>