axios.all()、axios.spread()两个辅助函数用于处理同时发送多个请求，可以实现在多个请求都完成后再执行一些逻辑。注意：该方法是axios的静态方法，不是axios实例的方法！

实例演示

<template>
  <div>
    <h1>Username: {{ userInfo.username }}</h1>
    <h1>Title: {{ memo.title }}</h1>
    <br>
    <br>
    <button @click="handleConcurrent">并发</button>
  </div>
</template>

<script>
import axios from 'axios'
export default {
  data () {
    return {
      userInfo: {
        username: 'lanyulei'
      },
      memo: {
        title: 'lanyulei-title'
      }
    }
  },
  mounted () {
    this.handleConcurrent()
  },
  methods: {
    handleConcurrent () {
      var _this = this
      axios.all([
        axios.get('/user.json'),
        axios.get('/memo.json')
      ]).then(axios.spread((userRes, memoRes) => {
        _this.userInfo = userRes.data
        _this.memo = memoRes.data
      })).catch(err => {
        console.log(err)
      })
    }
  }
}
</script>