title: Set input value by VueJS and mixing the content of value
body: <p>I try this:</p>
  
  <pre><code>&lt;input type="text"
      name="username"
      v-model="user.name"
      :value="'The user name is: '+user.name"&gt;
  </code></pre>
  
  <p>Is possible somehow to show in the input filed is "The user name is: John Doe" ?</p>
  
  <p>Or I need definitely use a computed value in this case?</p>