Sending HTTP Requests Reliably When a Page Unloads
Navigator.sendBeacon() is designed to send data when a page is unloaded. It guarantees delivery even if the page is closed. Basic usage: navigator.sendBeacon('/log', JSON.stringify({ some: 'data' })); The API does not allow custom headers. To send JSON with the proper Content-Type, use a Blob. <a href="/some-other-page" id="link">Go to Page</a> <script> document.getElementById('link').addEventListener('click', (e) => { const blob = new Blob([JSON.stringify({ some: 'data' })], { type: 'application/json; charset=UTF-8' }); navigator.sendBeacon('/log', blob); }); </script> Compared to fetch with keepalive, sendBeacon uses low priority, so it does not interfere with critical page actions....