title: How to evaluate Vue.js component props in the data property?
body: <p>I have 2 components: <code>Post</code> and <code>Comments</code>.</p>
  
  <p>Inside Post component, there is Comments component that has 3 props: <code>postId</code>, <code>numCom</code> (number of comments) and <code>comments</code> (array).</p>
  
  <p>I get comments and I pass the array with props, and now I want to retrieve the array in Comments component and add it to data so I can then add/remove comments etc.</p>
  
  <p>Here is my code in <code>Comments.vue</code>:</p>
  
  <pre><code>props: ['id', 'numCom', 'comments'],
  data: function() {
    return {
       newMessage: "",
       loading: false,
       allComments: this.comments,
       num: this.numCom,
     }
  },
  </code></pre>
  
  <p>But this doesn't works. In Vue developer tools I can see that <code>comments</code> prop is filled with comments, but <code>allComments</code> array is empty.</p>
  
  <p>What should I do?</p>