title: should navigator.sendBeacon be synchronous?
body: <p>I am using navigator.sendBeacon to send a small payload in the onclick event of an anchor</p>
  <pre><code>&lt;a href=&quot;https://someurl.com&quot; onclick=&quot;navigator.sendBeacon('https://internalurl.com/')&quot;&gt;Click Here&lt;/a&gt;
  </code></pre>
  <p>But it seems that the user does not navigate away until the server response is received from the sendBeacon call. i.e., if I put a breakpoint in my server-side endpoint, the browser does not navigate to 'https://someurl.com' until I hit continue on my server-side debugger. The docs (<a href="https://developer.mozilla.org/en-US/docs/Web/API/Navigator/sendBeacon" rel="nofollow noreferrer">https://developer.mozilla.org/en-US/docs/Web/API/Navigator/sendBeacon</a>) say the call should be async.</p>
  <p>Is this the expected behaviour or am I missing something?</p>