SOURCE

var Main = {
  data() {
    return {
      item: {name: 123}
    }
  },
  created() {
    setTimeout(() => {
      this.item = {name: 456}
    }, 1000)
  }
}
var Ctor = Vue.extend(Main)
new Ctor().$mount('#app')

<script src="https://cdn.bootcss.com/vue/2.5.17/vue.js"></script>
<script src="https://cdn.bootcss.com/element-ui/2.6.1/index.js"></script>
<div id="app">
<template>
<el-tabs type="border-card">
  <el-tab-pane>
    <span slot="label"><i class="el-icon-date"></i> {{item}}</span>
  </el-tab-pane>
</el-tabs>

</template>
</div>

@import url("https://cdn.bootcss.com/element-ui/2.6.1/theme-chalk/index.css");