写一套完整的uniapp省市区三级联动并返回地区code，用js地区数据

好的，以下是一套完整的uniapp省市区三级联动并返回地区code的代码，使用了JS地区数据：

<template>
  <view class="container">
    <view class="select-container">
      <picker mode="selector" :range="{{provinceList}}" :value="provinceIndex" @change="onProvinceChange">
        <view class="select-item">
          {{provinceList[provinceIndex]}}
        </view>
      </picker>
      <picker mode="selector" :range="{{cityList}}" :value="cityIndex" @change="onCityChange">
        <view class="select-item">
          {{cityList[cityIndex]}}
        </view>
      </picker>
      <picker mode="selector" :range="{{countyList}}" :value="countyIndex" @change="onCountyChange">
        <view class="select-item">
          {{countyList[countyIndex]}}
        </view>
      </picker>
    </view>
    <view class="result-container">
      <text>当前选择的地区编码为：{{selectedCode}}</text>
    </view>
  </view>
</template>

<script>
  export default {
    data() {
      return {
        provinceList: [], // 省份列表
        cityList: [], // 城市列表
        countyList: [], // 区县列表
        provinceIndex: 0, // 当前选中的省份下标
        cityIndex: 0, // 当前选中的城市下标
        countyIndex: 0, // 当前选中的区县下标
        provinceCode: '', // 当前选中的省份编码
        cityCode: '', // 当前选中的城市编码
        countyCode: '', // 当前选中的区县编码
        selectedCode: '', // 最终选择的地区编码
        data: [] // 地区数据
      }
    },

    mounted() {
      // 获取地区数据
      this.data = require('./area.js').default
      // 初始化省份列表
      this.provinceList = this.data.map(item => item.name)
      // 初始化城市列表
      this.cityList = this.data[this.provinceIndex].city.map(item => item.name)
      // 初始化区县列表
      this.countyList = this.data[this.provinceIndex].city[this.cityIndex].area.map(item => item.name)
      // 初始化编码
      this.provinceCode = this.data[this.provinceIndex].code
      this.cityCode = this.data[this.provinceIndex].city[this.cityIndex].code
      this.countyCode = this.data[this.provinceIndex].city[this.cityIndex].area[this.countyIndex].code
      this.selectedCode = this.countyCode
    },

    methods: {
      // 省份改变时触发
      onProvinceChange(e) {
        this.provinceIndex = e.detail.value
        this.cityIndex = 0
        this.countyIndex = 0
        this.cityList = this.data[this.provinceIndex].city.map(item => item.name)
        this.countyList = this.data[this.provinceIndex].city[this.cityIndex].area.map(item => item.name)
        this.provinceCode = this.data[this.provinceIndex].code
        this.cityCode = this.data[this.provinceIndex].city[this.cityIndex].code
        this.countyCode = this.data[this.provinceIndex].city[this.cityIndex].area[this.countyIndex].code
        this.selectedCode = this.countyCode
      },

      // 城市改变时触发
      onCityChange(e) {
        this.cityIndex = e.detail.value
        this.countyIndex = 0
        this.countyList = this.data[this.provinceIndex].city[this.cityIndex].area.map(item => item.name)
        this.cityCode = this.data[this.provinceIndex].city[this.cityIndex].code
        this.countyCode = this.data[this.provinceIndex].city[this.cityIndex].area[this.countyIndex].code
        this.selectedCode = this.countyCode
      },

      // 区县改变时触发
      onCountyChange(e) {
        this.countyIndex = e.detail.value
        this.countyCode = this.data[this.provinceIndex].city[this.cityIndex].area[this.countyIndex].code
        this.selectedCode = this.countyCode
      }
    }
  }
</script>

<style>
  .container {
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
  }

  .select-container {
    display: flex;
    flex-direction: row;
    justify-content: center;
    align-items: center;
  }

  .select-item {
    width: 200rpx;
    height: 80rpx;
    line-height: 80rpx;
    text-align: center;
  }

  .result-container {
    margin-top: 20px;
    font-size: 28rpx;
  }
</style>

需要注意的是，这里的地区数据是一个JS文件，需要单独引入，可以按照以下格式编写：

export default [
  {
    "code": "110000",
    "name": "北京市",
    "city": [
      {
        "code": "110100",
        "name": "北京市",
        "area": [
          {
            "code": "110101",
            "name": "东城区"
          },
          {
            "code": "110102",
            "name": "西城区"
          },
          {
            "code": "110105",
            "name": "朝阳区"
          },
          ...
        ]
      }
    ]
  },
  {
    "code": "120000",
    "name": "天津市",
    "city": [
      {
        "code": "120100",
        "name": "天津市",
        "area": [
          {
            "code": "120101",
            "name": "和平区"
          },
          {
            "code": "120102",
            "name": "河东区"
          },
          {
            "code": "120103",
            "name": "河西区"
          },
          ...
        ]
      }
    ]
  },
  ...
]

其中，每个省份包含一个code和一个name属性，以及一个city数组，每个城市包含一个code和一个name属性，以及一个area数组，每个区县包含一个code和一个name属性。