gistfile1.js

if (navigator.mozSetMessageHandler) {
  function NFCActivityHandler(activity) {
    var text = activity.source.data.text;
    if (!text) {
      updateText('No text record')
    }   
    else if (text.indexOf('bcm:') === 0) {
      var email = text.substr(4)
      registerRider(email)
      updateText('Registered ' + email)
    }   
    else {
      updateText(text)
    }   
  }

  navigator.mozSetMessageHandler('activity', NFCActivityHandler);
}