The onpeerlost event handler of the MozNFC interface handles the peerlost event, which is fired when the MozNFCPeer object received in MozNFC.onpeerready  is no longer available or not in proximinty (e.g. the peer device moves out of range.).

peerlost is only able to be fired for an app that has already previously received peerready. Image the following use case:

  1. In WebApp-Foo, a user bumps another device, and the Sharing UI pops up.
  2. The user shares the content, and the Sharing UI finishes.
  3. The user switches to another app, WebApp-Bar, which may have also registered peerlost
  4. The user now moves away from the other device. At this point Gecko will fire a peerlost event on the former foreground app, WebApp-Foo, because that's the app that received the peerready event.


attribute EventHandler onpeerlost;


var tnf     = 1;                                             // NFC Forum Well Known type
var type    = new Uint8Array(fromUTF8("U"));                 // URL type
var id      = new Uint8Array(fromUTF8(""));                  // id
var payload = new Uint8Array(fromUTF8("\")); // URL data, with a record prefix 0x3 replacing http://
var ndefRecords = [new MozNDEFRecord(tnf, type, id, payload)];
var nfcdom = window.navigator.mozNfc;

nfcdom.onpeerready = function(event) {
  var nfcPeer = nfcdom.getNFCPeer(event.detail);  // 'event.detail' has session id.
  var req = nfcpeer.sendNDEF(ndefRecords);        // push NDEF message to other NFC device.
  req.onsuccess = function(e) {
    console.log("Successfully pushed P2P message");
  req.onerror = function(e) {
    console.log("P2P push failed!");

nfcdom.onpeerlost() {
  console.log("Your peer has been lost.");




The NFC implementation in Gecko follows the NFC Forum specifications.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support

No support

No support No support No support No support
Feature Android Firefox Mobile (Gecko) Firefox OS (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support No support No support 2.0 moz [1] No support No support No support

[1] Available in privileged apps as of Firefox OS 2.2; certified-only before that.

See also


© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

API Firefox OS MozNFC NFC onpeerlost Property Reference