在这里输入代码`<template>
  <div class="list">
    <div class="item" v-for="item of letters" :key="item"
      @touchstart='handleTouchStart'
      @touchmove='handleTouchMove'
      @touchend='handleTouchEnd'
      @click='handleLetterClick'
      :ref="item"
    >
      {{item}}
    </div>
  </div>
</template>

<script>
export default {
  name: 'CityAlphabet',
  props: {
    cities: Object
  },
  computed: {
    letters () {
      const letters = []
      for (let i in this.cities) {
        letters.push(i)
      }
      return letters
    }
  },
  data () {
    return {
      touchStatus: false
    }
  },
  methods: {
    handleLetterClick (e) {
      console.log(e.target.innerText)
      this.$emit('change', e.target.innerText)
    },
    handleTouchStart () {
      this.touchStatus = true
    },
    handleTouchMove (e) {
      if (this.touchStatus) {
        const startY = this.$refs['A'][0].offsetTop
        const touchY = e.touches[0].clientY - 79
        const index = Math.floor((touchY - startY) / 20)
        if (index >= 0 && index < this.letters.length) {
          this.$emit('change', this.letters[index])
        }
      }
    },
    handleTouchEnd () {
      this.touchStatus = false
    }
  }
}
</script>

<style lang="stylus" scoped>
@import '~styles/varibles.styl'
.list
    display: flex
    flex-direction: column
    justify-content: center
    position: absolute
    top: 1.58rem
    right: 0
    bottom: 0
    width: .4rem
    .item
        line-height: .4rem
        text-align: center
        color: $bgColor
</style>
`