javascript Vue - 使用 refs 来聚焦元素目标

Vue - using refs to focus an element target

提问by Arel Lin

When span class="before-click" is clicked,
I want it hidden, and input class="after-click" show up instead.
And the showed up input tag must be on focused!
The problem is when I try to use $refs.afterClick to access that DOM and give it .focus(), an unexpected error shows that .focus() is not a function.
How to solve this issue? Thanks.

当 span class="before-click" 被点击时，
我希望它隐藏，而 input class="after-click" 会显示出来。
并且出现的输入标签必须是重点！
问题是当我尝试使用 $refs.afterClick 访问该 DOM 并给它 .focus() 时，一个意外错误表明 .focus() 不是一个函数。
如何解决这个问题？谢谢。

var myApp = new Vue({
  el: '#app',
  data: {
    onEdit: false,
    msg: 'Something in here',
  },
  methods: {
    switchAndFocus() {
      if(!this.onEdit) {
       this.onEdit = true;
       this.$refs.afterClick.focus();
      }
    },
  },
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.3/vue.min.js"></script>
<div id="app">
  <span class="before-click" @click="switchAndFocus()" v-show="!onEdit">{{msg}}</span>
  <input type="text" class="after-click" ref="afterClick" :value="msg" v-show="onEdit">
</div>

回答by tom_h

Wrap the focus event in a nextTick - this will defer the focus event until the DOM has updated and displayed the input.

将焦点事件包装在 nextTick 中 - 这将推迟焦点事件，直到 DOM 更新并显示输入。

https://vuejs.org/v2/api/#Vue-nextTick

https://vuejs.org/v2/api/#Vue-nextTick

var myApp = new Vue({
  el: '#app',
  data: {
    onEdit: false,
    msg: 'Something in here',
  },
  methods: {
    switchAndFocus() {
      if(!this.onEdit) {
       this.onEdit = true;
       this.$nextTick(function(){
        this.$refs.afterClick.focus();
       });
      }
    },
  },
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.3/vue.min.js"></script>
<div id="app">
  <span class="before-click" @click="switchAndFocus()" v-show="!onEdit">{{msg}}</span>
  <input type="text" class="after-click" ref="afterClick" :value="msg" v-show="onEdit">
</div>