title: Vuejs Hide a div when v-model is empty
body: <p>I have a select dropdown like this.</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;select v-model="selectedInjection"&gt;
      &lt;option v-for="(match,i) in haufigkeitMatches"
          :key="i"
          :value="match.value" &gt;{{ match.name }}
      &lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>I am rendering the value in this way </p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;td v-if="selectedInjection"&gt;{{Math.round(selectedInjection)}&lt;/td&gt;
  </code></pre>
  
  <p>The value of the <code>{{Math.round(selectedInjection)}</code> changes when the select value changes and it's working fine. But when I do not select any value, the <code>{{Math.round(selectedInjection)}</code> is showing the old selected value unless I select a new value. 
  How can I hid the <code>{{Math.round(selectedInjection)}</code> when the select value is empty?</p>
  
  <p>Here is the Jsfiddle <a href="https://jsfiddle.net/ey3scra0/" rel="nofollow noreferrer">https://jsfiddle.net/ey3scra0/</a></p>