title: Allow only numbers to be typed in a textbox
body: <p>How to allow only numbers to be written in this textbox ?</p>
  <pre><code>&lt;input type=&quot;text&quot; class=&quot;textfield&quot; value=&quot;&quot; id=&quot;extra7&quot; name=&quot;extra7&quot;&gt;
  </code></pre>