vue + elementUI 省市县三级联动

1、首先需要准备省市县json文件，网上有很多可以下载。项目中使用的city.json数据是这样的格式：

[
  {
    "value": "110000",
    "label": "北京市",
    "children": [
      {
        "value": "110000",
        "label": "北京市",
        "children": [
          {
            "value": "110101",
            "label": "东城区"
          },
          {
            "value": "110102",
            "label": "西城区"
          },
          {
            "value": "110105",
            "label": "朝阳区"
          },
          {
            "value": "110106",
            "label": "丰台区"
          },
          {
            "value": "110107",
            "label": "石景山区"
          },
          {
            "value": "110108",
            "label": "海淀区"
          },
          {
            "value": "110109",
            "label": "门头沟区"
          },
          {
            "value": "110111",
            "label": "房山区"
          },
          {
            "value": "110112",
            "label": "通州区"
          },
          {
            "value": "110113",
            "label": "顺义区"
          },
          {
            "value": "110114",
            "label": "昌平区"
          },
          {
            "value": "110115",
            "label": "大兴区"
          },
          {
            "value": "110116",
            "label": "怀柔区"
          },
          {
            "value": "110117",
            "label": "平谷区"
          },
          {
            "value": "110118",
            "label": "密云区"
          },
          {
            "value": "110119",
            "label": "延庆区"
          }
        ]
      }
    ]
  },
  {
    "value": "120000",
    "label": "天津市",
    "children": [
      {
        "value": "120000",
        "label": "天津市",
        "children": [
          {
            "value": "120101",
            "label": "和平区"
          },
          ......

2、创建一个组件开始写代码

<template>
  <div class="linkage">
    <div>
      <el-select v-model="selectProvince" filterable size="small" @change="selectProvinceFun($event)" placeholder="请选择省份">
        <el-option value="" label="请选择省份"></el-option>
        <el-option :value="item" :label="item.label" v-for="(item, index) in city" :key="index"></el-option>
      </el-select>
    </div>
    <div>
      <el-select v-model="selectCity" filterable size="small" @change="selectCityFun($event)" placeholder="请选择城市">
        <el-option value="" label="请选择城市"></el-option>
        <el-option :value="item" :label="item.label" v-for="(item, index) in cityList" :key="index"></el-option>
      </el-select>
    </div>
    <div>
      <el-select v-model="selectArea" filterable size="small" @change="selectAreaFun($event)" placeholder="请选择区县">
        <el-option value="" label="请选择区县"></el-option>
        <el-option :value="item" :label="item.label" v-for="(item, index) in areaList" :key="index"></el-option>
      </el-select>
    </div>
  </div>
</template>
<script>
import city from '@/assets/json/city.json'
export default {
  name: 'linkage',
  data () {
    return {
      // 整个省市县数据
      city: city,
      // 被选中的市数据
      cityList: [],
      // 被选中的县数据
      areaList: [],
      selectProvince: {},
      selectCity: {},
      selectArea: {}
    }
  },
  mounted () {
  },
  methods: {
    // 省份 市 县联动
    selectProvinceFun (event) {
      console.log(event)
      if (event) {
        this.cityList = event.children
      } else {
        this.cityList = []
      }
      this.areaList = []
      this.$emit('getLawyerListInfo', [event.label, 'province'])
    },
    selectCityFun (event) {
      console.log(event)
      if (event) {
        this.areaList = event.children
      } else {
        this.areaList = []
      }
      this.$emit('getLawyerListInfo', [event.label, 'city'])
    },
    selectAreaFun (event) {
      console.log(event)
      this.$emit('getLawyerListInfo', [event.label, 'area'])
    }
  }
}
</script>
<style lang="scss" scoped>
  .linkage {
    display: flex;
    div {
      margin-right: 5px;
    }
  }
</style>

总结：整个过程很简单，就是在选中省的时候获取他的所有children节点数据（市）在选择市的时候获取她的所有children节点数据（区县）