jargon

Frontend & browser·The network from the browser

you sent the analytics event on page unload and it actually arrived, instead of being cancelled.

Beacon

Also calledsendBeacon, keepalive request

A small request the browser promises to deliver even after the page goes away, via `navigator.sendBeacon` or `fetch` with `keepalive`. It exists because unload handlers are the one place a normal request is routinely killed mid-flight. The payload limit is small, the method is POST, and you get no response back, so it is for telemetry and nothing else.

Commonly confused with