vant的picker组件设置文字超长滚动方式

<template>
  <div id="app">
    <van-picker show-toolbar title="标题" :columns="columns" @change="checkScroll" />
  </div>
</template>
<script>
export default {
  name: 'App',
  data () {
    return {
      columns: [{
        text: '浙江',
        children: [{
          text: '温州温州温州温州温州温州温州-杭州',
          children: [{ text: '西湖区' }, { text: '余杭区' }],
        }, {
          text: '温州温州温州温州温州温州温州-温州',
          children: [{ text: '鹿城区' }, { text: '瓯海区' }],
        }]
      }]
    }
  },
  methods: {
    checkScroll () {
      this.$nextTick(() => {
        // 获取选中元素
        let selectedItems = [...document.querySelectorAll('.van-picker-column__item--selected')]
        selectedItems.forEach(item => {
          let child = item.querySelector('.van-ellipsis')
          if (child.offsetWidth > item.offsetWidth) { // 判断child文字宽度
            item.classList.add('scroll')
          } else {
            item.classList.remove('scroll')
          }
        })
      })
    }
  }
}
</script>

<style lang="less" scoped>
/deep/ .van-picker-column__item--selected {
  
  .van-ellipsis {
    text-overflow: unset;
    overflow: visible;
  }
  
  &.scroll > .van-ellipsis {
    animation: move 4s linear infinite;
  }
}
@keyframes move {
  0% { transfORM: translateX(100%); }
  100% { transform: translateX(-100%); }
}
</style>

<van-field
  readonly
  clickable
  label="城市"
  :value="value"
  placeholder="选择城市"
  @click="showPicker = true"
/>
<van-popup v-model="showPicker" round position="bottom">
  <van-picker
    show-toolbar
    :columns="columns"
    value-key="name" 
    @cancel="showPicker = false"
    @confirm="onConfirm"
  />
</van-popup>
<!--
重点：自定义value-key属性：默认值是text
value-key这个属性是自定义后台返回字段作为选择器显示的内容，这样后台返回的字段位未name时，也可以显示了。
否则默认的原始对象默认是[{text:'选项一',value:'1'},{text:'选项二',value:'2'}]
-->