Edit in JSFiddle

var Main = {
  data() {
    return {
      input: '',
      index: 2
    }
  },
  methods: {
  	handlerInput($event, index) {
   		// $event 相当于 v-model
      console.log($event)
      console.log(index)
    }
  }  
}
var Ctor = Vue.extend(Main)
new Ctor().$mount('#app')

<script src="//unpkg.com/vue/dist/vue.js"></script>
<script src="//unpkg.com/[email protected]/lib/index.js"></script>
<div id="app">
<el-input v-model="input" @input="handlerInput($event, index)" placeholder="请输入内容"></el-input>
</div>

@import url("//unpkg.com/[email protected]/lib/theme-default/index.css");