title: Set IFrame allowfullscreen with javascript
body: <p>I tried to set allowfullscreen attribute to the iframe, but it doesn't work:</p>
  
  <pre><code>iframe.allowFullScreen = true
  </code></pre>
  
  <p>I checked it with chrome -> inspect element, but the iframe has no allowfullscreen attribute, after this code.</p>
  
  <p>Thanks in advance,</p>