title: Is it possible to know which button the user click on when opening a dialog to launch external handler?
body: <p>I have HTML code below:</p>
  <pre><code>&lt;a href=&quot;app_protocol:test@gmail.com&quot;&gt;Open app&lt;/a&gt;
  </code></pre>
  <p>When users click on the anchor, the browser will show a dialog to ask them to open the desktop app (myapp) or not. How to know which button the user clicks on: Cancel or Open?
  Thanks!</p>
  <p><a href="https://i.stack.imgur.com/VMQJe.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VMQJe.jpg" alt="enter image description here" /></a></p>