The navigator.sendBeacon() method can be used to asynchronously transfer small HTTP data from the User Agent to a web server.
The navigator.sendBeacon() method can be used to asynchronously transfer small HTTP data from the User Agent to a web server.
MDN
The url parameter indicates the resolved URL where the data is to be transmitted.
The data parameter is the ArrayBufferView, Blob, DOMString, or FormData data that is to be transmitted.