Widely available Supported across all major browsers. Safe to use in production.

Beacons

The navigator.sendBeacon() method asynchronously sends an HTTP POST request containing a small amount of data to a web server.

It's intended to be used for sending analytics data to a web server, and avoids some of the problems with legacy techniques for sending analytics, such as the use of XMLHttpRequest.

Networking

Browser support

Feature Desktop Mobile
Chrome
Edge
Firefox
Safari
Chrome Android
Safari iOS
sendBeacon
39
14
31
11.1
42
11.3
1+Supported (version) Not supported ※Has note Sub-feature descriptions sourced from MDN Web Docs (CC BY-SA 2.5)
Notes 1 item(s)
Implementation note
  • Starting in Chrome 59, this method cannot send a `Blob` whose type is not CORS safelisted. This is a temporary change until a mitigation can be found for the security issues that this creates. For more information, see bug 40087600.
Notes 1 item(s)
Implementation note
  • Starting in Chrome 59, this method cannot send a `Blob` whose type is not CORS safelisted. This is a temporary change until a mitigation can be found for the security issues that this creates. For more information, see bug 40087600.

Syntax

JAVASCRIPT 
document.addEventListener("visibilitychange", () => {
  if (document.visibilityState === "hidden") {
    navigator.sendBeacon("/log", analyticsData);
  }
});

Use cases

  • Using Beacons

    The navigator.

Cautions

  • May not be supported in older browsers.

Implementation notes

  • Some APIs require a secure context (HTTPS) or user activation. Check the requirements before use.

Related links