title: Vue js spread syntax with Vuex
body: <p>When using <a href="https://vuex.vuejs.org/guide/state.html" rel="noreferrer">vuex mapState</a>, the documentation says you can use 
  spread syntax as below, which I have working as intended.</p>
  
  <p>I'm just curious as to what this is actually doing, so I have a better understanding of using spread syntax.</p>
  
  <p>Would this...</p>
  
  <pre><code>computed: {
    ...mapState([
      'message',
      'storeArray'
    ])
  }
  </code></pre>
  
  <p>Be effectively doing this... ?</p>
  
  <pre><code>computed: {
    message(){
      return this.$store.state.message
    }
    storeArray(){
      return this.$store.state.storeArray
    }
  }
  </code></pre>