title: Check in JavaScript if an SSL Certificate is valid
body: <p>Is there a way to check in JavaScript if given a host its SSL certificate is valid? (non blocking)</p>
  <p>In my case, I want to display: &quot;you can also use https://..&quot; if via JavaScript I can make a request to <code>https://my_url</code> without being asked to accept an untrusted certificate.</p>
  <p>Can this be done asynchronously?</p>