export default {
 100000: {
 110000: '北京市',
 120000: '天津市',
 130000: '河北省',
 140000: '山西省',
 ...
 },
 130000: {
 130100: '石家莊市',
 130200: '唐山市',
 130300: '秦皇島市',
 130400: '邯鄲市',
 ...
 },
 130100: {
 130102: '長安區(qū)',
 130104: '橋西區(qū)',
 130105: '新華區(qū)',
 130107: '井陘礦區(qū)',
 ...
 },
 ...
}

<template>
 <div id="app" class="container">
 <div class="demo form-inline">
  <select name="province" class="form-control" v-model="province.code" @change="getCitys">
   <option value="">選擇省份</option>
   <option v-for="(item, index) in provinceList"
    :value="index"
    :key="index">
   {{ item }}
   </option>
  </select>
  <select name="city" class="form-control" v-show="showcitys" v-model="city.code" @change="getAreas">
   <option value="">選擇城市</option>
   <option v-for="(item, index) in cityList"
    :value="index"
    :key="index">
   {{ item }}
   </option>
  </select>
  <select name="area" class="form-control" v-show="showareas" v-model="area.code" @change="getDistValue">
   <option value="">選擇區(qū)縣</option>
   <option v-for="(item, index) in areaList"
    :value="index"
    :key="index">
   {{ item }}
   </option>
  </select>
  <button class="btn btn-info" @click="getSelectVal">獲取選中值</button>
  <div style="margin-top:20px;color:red">{{selected}}</div>
 </div>
 </div>
</template>

import DISTRICTS from './districts';
const DEFAULT_CODE = 100000;
export default {
 name: 'App',
 data() {
  return {
   showcitys: false,
   showareas: false,
   selected: '',
   defaultProvince: '湖南省',
   defaultCity: '長沙市',
   defaultArea: '岳麓區(qū)',
   province: {},
   city: {},
   area: {},
   provinceList: [],
   cityList: [],
   areaList: []
  }
 },
 created() {
  this.provinceList = this.getDistricts();
  this.getDefault();
 },
 
 methods: {
  getDefault() {
   if (this.defaultProvince !== '') {
    this.showcitys = true;
    let provinceCode = this.getAreaCode(this.defaultProvince);
    this.cityList = this.getDistricts(provinceCode);
    this.province = {
     code: provinceCode,
     value: this.defaultProvince
    }
   }
   
   if (this.defaultCity !== '') {
    this.showareas = true;
    let cityCode = this.getAreaCode(this.defaultCity);
    this.areaList = this.getDistricts(cityCode);
    this.city = {
     code: cityCode,
     value: this.defaultCity
    }
   }
 
   if (this.defaultArea !== '') {
    let areaCode = this.getAreaCode(this.defaultArea);
    this.area = {
     code: areaCode,
     value: this.defaultArea
    }
   }
  },
  getSelectVal() {
   this.selected = this.province.value + this.city.value + this.area.value;
   console.log(this.province.code + '-'+ this.city.code + '-' + this.area.code);
  },
  
  //名稱轉(zhuǎn)代碼
  nameToCode(name) {
   for(let x in DISTRICTS) {
   for(let y in DISTRICTS[x]) {
    if(name === DISTRICTS[x][y]) {
    return y
    }
   }
   }
  },
  //獲取區(qū)域代碼
  getAreaCode(value) {
   if(typeof value === 'string') {
   return this.nameToCode(value);
   }

   return value;
  },
  
  getCodeValue(code, level=1) {
   if (level == 1) { //省級
    return DISTRICTS[DEFAULT_CODE][code];
    
   } else if (level == 2) {
    let provinceCode = this.province.code;
    return DISTRICTS[provinceCode][code];
  
   } else { //
    let cityCode = this.city.code;
    return DISTRICTS[cityCode][code];
   }
  },
  getDistricts(code = DEFAULT_CODE) {
   return DISTRICTS[code] || []
  },
  
  cleanList(name) {
   this[name] = []
  },
  getCitys(e) {
   this.cityList = this.getDistricts(e.target.value);

   this.cleanList('areas')
   this.province = this.setData(e.target.value, 1);
   this.areaList = [];
   this.showareas = false;
   this.showcitys = true;
  },
  getAreas (e) {
   this.areaList = this.getDistricts(e.target.value);
   this.city = this.setData(e.target.value, 2);
   this.showareas = true;
  },
  getDistValue (e) {
   this.area = this.setData(e.target.value, 3);
  },
  setData(code, level = 1) {
   code = parseInt(code);
   return {
    code: code,
    value: this.getCodeValue(code, level),
   }
  },

 }
}