How To Beacon

Demo how to beacon data from browser to server reliably.

Read the post on https://dev.to/xgwang/you-may-not-know-beacon-9ba

TL;DR

Use navigator.sendBeacon on visibilitychange and beforeunload event. Once your lowest browser supports https://bugs.webkit.org/show_bug.cgi?id=151234 fires on visibilitychange only.

Read Details

• https://developers.google.com/web/updates/2018/07/page-lifecycle-api
• https://www.igvita.com/2015/11/20/dont-lose-user-and-app-state-use-page-visibility/
• https://developer.mozilla.org/en-US/docs/Web/API/Navigator/sendBeacon
• Fetch keepalive