Testing navigator.sendBeacon() cross-origin. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS navigator.sendBeacon("http://localhost:8000/blink/sendbeacon/resources/save-beacon.php?name=cross-origin", "CrossOrigin"); is true PASS Beacon sent successfully PASS Content-Type: text/plain;charset=UTF-8 PASS Origin: http://127.0.0.1:8000 PASS Referer: http://127.0.0.1:8000/ PASS Request-Method: POST PASS Length: 11 PASS Body: CrossOrigin PASS PASS successfullyParsed is true TEST COMPLETE