方案一

使用components注册,这个跟Vue2是一样的

import {
  Field,
  CellGroup, Popup, Notify
} from 'vant';
 export default defineComponent({
     name: "NamePopup",
     components: {
         [Field.name]: Field,
         [CellGroup.name]: CellGroup,
         [Popup.name]: Popup,
     },
     setup(props, { emit }) {
     }
 });

<van-popup
      v-model:show="showPopup"
      position="bottom"
      :style="{ height: '100%' }"
      teleport="body"
    >
    <van-cell-group v-if="showPopup" inset>
      <van-field
        @input="updateInputVal"
        v-model="nameDec"
        rows="2"
        autosize
        type="textarea"
        maxlength="10"
      />
    </van-cell-group>
</van-popup>

方案二

怎么引入，怎么使用，下面这个方案更常用一些，现在常用script+setup的模式

<script setup>
import {
  Field,
  CellGroup, Popup, Notify
} from 'vant';
</script>

<template>
  <Popup v-model:show="showPopup" position="bottom" :style="{ height: '100%' }" teleport="body">
    <CellGroup inset>
      <Field @input="updateInputVal" v-model="nameDesc" rows="2" autosize type="textarea" maxlength="10"
        />
    </CellGroup>
  </Popup>
</template>