title: JSSDK Unknown Host domain
body: <p>With the new <a href="https://developers.facebook.com/docs/facebook-login/changelog" rel="noreferrer">Facebook changes on August 1, 2021</a> (I think) the Developer Dashboard &gt; Facebook Login settings have been updated and now include a <strong>Allowed Domains for the JavaScript SDK</strong> section.</p>
  <h3>The Problem</h3>
  <p>I cannot add a <strong>port number</strong> to the domain like I can in the <em>Valid OAuth Redirect URIs</em> section. After clicking <strong>Save Changes</strong> the port numbers are removed from the entries. Our app is currently in development, and while serving the app from <code>https://www.example.localhost:4200</code> we are given the error while using the <a href="https://developers.facebook.com/docs/javascript" rel="noreferrer">Facebook JavaScript SDK</a>:</p>
  <blockquote>
  <p>JSSDK Unknown Host domain: The Domain you are hosting the Facebook Javascript SDK is not in your app's Javascript SDK host domain list. Please specify your host domain in App dashboard login settings.</p>
  </blockquote>
  <p><a href="https://i.stack.imgur.com/zAorq.png" rel="noreferrer"><img src="https://i.stack.imgur.com/zAorq.png" alt="Facebook Error Image" /></a></p>