1、效果

省份没选之前，市与区禁选，同理市未选择，区也是禁用的重新选择省，市与区的也会清空，同理重新选择市，区也会重置，完整代码地址

 选择的时候就是下面这样的

2、主要逻辑代码

html相关代码

<template>

<div class="area-component">
  <!-- 省 -->
  <el-select
    placeholder="请选择省份"
    v-model="state.params.province"
    clearable
  >
    <el-option
      v-for="item in state.showData.province"
      :key="item.code"
      :label="item.name"
      :value="item.code"
    />
  </el-select>
  <!-- 市 -->
  <el-select
    placeholder="请选择城市"
    style="margin: 0 10px;"
    :disabled="!state.params.province"
    v-model="state.params.city"
    clearable
  >
    <el-option
      v-for="item in state.showData.cities"
      :key="item.code"
      :label="item.name"
      :value="item.code"
    />
  </el-select>
  <!-- 区 -->
  <el-select
    placeholder="请选择区"
    :disabled="!state.params.province || !state.params.city"
    v-model="state.params.area"
    clearable
  >
    <el-option
      v-for="item in state.showData.areas"
      :key="item.code"
      :label="item.name"
      :value="item.code"
    />
  </el-select>
</div>

</template>

 逻辑处理部分

import { reactive, onBeforeMount, computed, watch } from 'vue'
import areaData from '@/components/myArea/data/pca-code.json'

// 定义数据类型
export interface areaType {
  code: string
  name: string
  children?: areaType[]
}

// 父组件爱传过来的事件，用于接收省市区选择后的数据
const emits = defineEmits<{
  (e: 'areaChange', value: any):void
}>()

const state = reactive({
  // 用于展示的省市区数据
  showData:{
    province: [] as areaType[],
    cities: [] as areaType[],
    areas: [] as areaType[],
  },
  // 最终选择的省市区
  params:{
    province: undefined,
    city: undefined,
    area: undefined
  }
})
// 准备省市区展示数据
onBeforeMount(()=>{
  state.showData.province = areaData.map((item) => ({code: item.code, name:item.name}))
})
state.showData.cities = computed(()=>{
  return areaData.find((item)=>item.code === state.params.province)?.children
}) as any
state.showData.areas = computed(()=>{
  return state.showData.cities?.find((item)=>item.code === state.params.city)?.children
}) as any

// 监听省、市、地区的变化的变化
watch(()=>state.params.province, ()=>{
  state.params.city = undefined
  state.params.area = undefined
})
watch(()=>state.params.city, ()=>{
  state.params.area = undefined
})
watch(()=>state.params.area, (val)=>{
  // 区有值的时候，省市必定有值，此时就可以将数据返回给父组件
  if(val){
    // 组装数据
    const paramsData = {
      province: {} as areaType,
      city: {} as areaType,
      area: {} as areaType
    }
    let tmp = areaData.find((item) => item.code === state.params.province)
    paramsData.province.name = tmp?.name as string
    paramsData.province.code = tmp?.code as string
    tmp = tmp?.children.find((item) => item.code === state.params.city) as any
    paramsData.city.name = tmp?.name as string
    paramsData.city.code = tmp?.code as string
    tmp = tmp?.children.find((item) => item.code === state.params.area) as any
    paramsData.area.name = tmp?.name as string
    paramsData.area.code = tmp?.code as string

    // 出触发父组件事件，传数据过去
    emits('areaChange', paramsData)
  }
})

以上便是省市区组件代码，欢迎大佬们批评指正！！