<template>
   <div class="goodList" ref="goodList">
      <dl  class="foodList" v-for="(item, index) in goods" :key="index" ref="foodList">
        <dt class="name">{{item.name}}</dt>
        <dd class="food" v-for="(food, i) in item.foods" :key="i">
          <img :src="food.image" :alt="food.name" width="57" height="57">
        </dd>
      </dl>
    </div>
  </div>
</template>

<script>
import axios from 'axios'
export default {
  methods: {
    // 后台数据
    get_goods () {
      axios.get('/goods')
        .then(res => {
          let { status, data: { errno, data: data2 } } = res
          if (status === 200) {
            if (errno === 0) {
              this.goods = data2
              console.log(this.$refs.foodList)  ===>undefined
              console.log(this.$refs.goodList)  ===><div class="goodList">...</div>
    })
              this.$nextTick(() => {
                console.log(this.$refs.foodList) ===><div class="foodList">...</div>
    })
                console.log(this.$refs.goodList) ===><div class="goodList">...</div>
    })
              })
            }
          }
        })
        .catch(res => {
          console.log(res)
        })
    }
  },
  created () {
    this.get_goods()
    console.log(this.$refs.foodList)   ===>undefined
    console.log(this.$refs.goodList)   ===>undefined
    this.$nextTick(() => {
      console.log(this.$refs.foodList) ===>undefined
      console.log(this.$refs.goodList) ===><div class="goodList">...</div>
    })
  },
  mounted() {
    console.log(this.$refs.foodList)  ===>undefined
    console.log(this.$refs.goodList)  ===><div class="goodList">...</div>
    this.$nextTick(() => {
      console.log(this.$refs.foodList) ===>undefined
      console.log(this.$refs.goodList) ===><div class="goodList">...</div>
    })
  }
}

在网上看到： ref 最好在页面渲染（mounted）以后使用，在页面渲染前（mounted前）使用可以在this.$nextTick()函数中
有三个疑问：
1.在created生命周期函数中，this.$nextTick()为什么不能获取v-for的foodList？
2.在mounted生命周期函数中，页面渲染后，使用和未使用this.$nextTick()，有什么区别？ 及this.$nextTick()为什么不能获取v-for的foodList？
3.在created生命周期函数中，向后台获取数据，使用this.$nextTick()，为什么能获取v-for的foodList
请各路大神指点指点，非常感谢### 问题描述

问题出现的环境背景及自己尝试过哪些方法

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