Does espruino support bonding with a pin?

Hmm, ok - looks like you are both trying to use the same device then!

So... I've just tried to add the security, but I have no way to actually test. You should be able to do:

NRF.setSecurity({keyboard:1});
// find device with NRF.requestDevice/etc
dev.on('passkeyRequest', function() {
  // then you need to call the following after you've had a chance to get it
  dev.sendPasskey("123456")
});

I have also added support for Indications (I hope!) - startNotifications will just use indicate if notify isn't there (as the Web Bluetooth spec seems to imply it should).

Builds are available at http://www.espruino.com/binaries/travis/master/

Please let me know how you get on!