Check if your browser is compatible with some latest feature (async here).
Redirects to a basic HTML page that invites your viewer to download Firefox, Chromium or Google Chrome.
This project is espacially useful when your web-app depends on some recent feature like Lego and you can't or don't want to bother with retrocompatibility compilers and issues.
Just include the check.js script in priority of your head:
<meta…>
<title>…</title>
<script src=https://cdn.jsdelivr.net/gh/polight/browser-compatibility@master/check.js></script>
…