vuejs v-model, multiple checkbox and computed property

Question

I am trying to use multiple checkboxes in single file component. And I need to computed property, but I have boolean newVal instead of array in my setter. Here is my code:

Answer 1

Here it is the working version:

var demo = new Vue({
  el: '#demo',
  data: {
    checkedNames: []
  }
})

<script src="https://unpkg.com/vue@2.1.10/dist/vue.js"></script>
<div id="demo">
  <input type="checkbox" id="jack" value="Jack" v-model="checkedNames">
  <label for="jack">Jack</label>
  <input type="checkbox" id="john" value="John" v-model="checkedNames">
  <label for="john">John</label>
  <input type="checkbox" id="mike" value="Mike" v-model="checkedNames">
  <label for="mike">Mike</label>
  <br>
  <span>Checked names: {{ checkedNames }}</span>
</div>

if you want to use a computed property you can use it in this way:

var demo = new Vue({
  el: '#demo',
  data: {
    checkedNames: []
  },
  computed : {
    checkedComputed () {
      return this.checkedNames
    }
  }
})

<script src="https://unpkg.com/vue@2.1.10/dist/vue.js"></script>
<div id="demo">
  <input type="checkbox" id="jack" value="Jack" v-model="checkedNames">
  <label for="jack">Jack</label>
  <input type="checkbox" id="john" value="John" v-model="checkedNames">
  <label for="john">John</label>
  <input type="checkbox" id="mike" value="Mike" v-model="checkedNames">
  <label for="mike">Mike</label>
  <br>
  <span>Checked Names :</span>
  <span>{{ checkedComputed }}</span>
</div>

Answer 2

Properties that start with _ or $ will not be proxied on the Vue instance because they may conflict with Vue’s internal properties and API methods. You will have to access them as vm.$data._property.

From the official documentation.