IView中on-change属性如何使用

<Form-item label="所在地区" >
   <Row >
   <Col span="12">
   <select v-model="f.p" @change="selpro" placeholder="sheng">
    <option :value="i" v-for="(v,i) in pro">{{v.name}}</option>
   </select>
   </Col>
   <Col span="12">
   <select v-model="f.c" @change="selcity" placeholder="shi">
    <option :value="i" v-for="(v,i) in city">{{v.name}}</option>
   </select>
   </Col>
   <Col span="12">
   <select v-model="f.cc" v-show="county.length>0" @change="result" placeholder="xian"> 
    <option :value="i" v-for="(v,i) in county">{{v.name}}</option>
   </select>
   </Col>
   </Row>
  </Form-item>

<Form-item label="所在地区">
    <Row>
     <i-col span="12">
      <i-select v-model="f.p" @on-change="selpro" placeholder="sheng">
       <i-option :value="i" v-for="(v,i) in pro" :key="v.id">{{v.name}}</i-option>
      </i-select>
     </i-col>
     <i-col span="12">
      <i-select v-model="f.c" @on-change="selcity" placeholder="shi">
       <i-option :value="i" v-for="(v,i) in city" :key="v.id">{{v.name}}</i-option>
      </i-select>
     </i-col>
     <i-col span="12">
      <i-select v-model="f.cc" v-show="county.length>0" onchange="result" placeholder="xian">
       <i-option :value="i" v-for="(v,i) in county" :key="v.id">{{v.name}}</i-option>
      </i-select>
     </i-col>
    </Row>
   </Form-item>