app.js

var compatibleDevices = [
  {
    deviceName: 'ACR122U USB NFC Reader',
    productId: 0x2200,
    vendorId: 0x072f,
    thumbnailURL: chrome.runtime.getURL('images/acr122u.png')
  },
  {
    deviceName: 'SCL3711 Contactless USB Smart Card Reader',
    productId: 0x5591,
    vendorId: 0x04e6,
    thumbnailURL: chrome.runtime.getURL('images/scl3711.png')
  }
]

var device = null;

function log(message, object) {
  var logArea = document.querySelector('.logs');
  var pre = document.createElement('pre');
  pre.textContent = message;
  if (object)
    pre.textContent += ': ' + JSON.stringify(object, null, 2) + '\n';
  logArea.appendChild(pre);
  logArea.scrollTop = logArea.scrollHeight;
  document.querySelector('#logContainer').classList.remove('small');
}

function handleDeviceTimeout(func, args) {
  var timeoutInMs = 1000;
  var hasTags = false;
  setTimeout(function() {
    if (!hasTags) {
      log('Timeout! No tag detected');
    }
  }, timeoutInMs);
  var args = args || [];
  args = args.concat([function() { hasTags = true; }]);
  func.apply(this, args);
}

function onReadNdefTagButtonClicked() {
  handleDeviceTimeout(readNdefTag);
}

function readNdefTag(callback) {
  chrome.nfc.read(device, {}, function(type, ndef) {
    log('Found ' + ndef.ndef.length + ' NFC Tag(s)');
    for (var i = 0; i < ndef.ndef.length; i++)
      log('NFC Tag', ndef.ndef[i]);
    callback();
  });
}

function onReadMifareTagButtonClicked() {
  handleDeviceTimeout(readMifareTag);
}

function readMifareTag(callback) {
  var blockNumber = 0; // starting logic block number.
  var blocksCount = 2; // logic block counts.
  chrome.nfc.read_logic(device, blockNumber, blocksCount, function(rc, data) {
    log('Mifare Classic Tag', UTIL_BytesToHex(data));
    callback();
  });
}

function onWriteNdefTagButtonClicked() {
  var ndefType = document.querySelector('#write-ndef-type').value;
  var ndefValue = document.querySelector('#write-ndef-value').value;
  handleDeviceTimeout(writeNdefTag, [ndefType, ndefValue]);
}

function writeNdefTag(ndefType, ndefValue, callback) {
  var ndef = {};
  ndef[ndefType] = ndefValue;
  chrome.nfc.write(device, {"ndef": [ndef]}, function(rc) {
    if (!rc) {
      log('NFC Tag written!');
    } else {
      log('NFC Tag write operation failed', rc);
    }
    callback();
  });
}

function onWriteMifareTagButtonClicked() {
  try {
    var mifareData = JSON.parse(document.querySelector('#mifare-data').value);
    handleDeviceTimeout(writeMifareTag, [mifareData]);
  }
  catch(e) {
    log('Error', 'Mifare Data is not an Array.');
  }
}

function writeMifareTag(mifareData, callback) {
  var data = new Uint8Array(mifareData);
  var blockNumber = 0; // starting logic block number.
  chrome.nfc.write_logic(device, 0, data, function(rc) {
    if (!rc) {
      log('Mifare Tag written!');
    } else {
      log('Mifare Tag write operation failed', rc);
    }
    callback();
  });
}

function onEmulateTagButtonClicked() {
  var ndefType = document.querySelector('#emulate-ndef-type').value;
  var ndefValue = document.querySelector('#emulate-ndef-value').value;
  handleDeviceTimeout(emulateTag, [ndefType, ndefValue]);
}

function emulateTag(ndefType, ndefValue, callback) {
  var ndef = {};
  ndef[ndefType] = ndefValue;
  chrome.nfc.emulate_tag(device, {"ndef": [ndef]}, function(rc) {
    if (!rc) {
      log('NFC Tag emulated!');
    } else {
      log('NFC Tag emulate operation failed', rc);
    }
    callback();
  });
}

function showDeviceInfo() {
  var deviceInfo = null;
  for (var i = 0; i < compatibleDevices.length; i++)
    if (device.productId === compatibleDevices[i].productId && 
        device.vendorId === compatibleDevices[i].vendorId)
      deviceInfo = compatibleDevices[i];
    
  if (!deviceInfo)
    return;
  
  var thumbnail = document.querySelector('#device-thumbnail');
  thumbnail.src = deviceInfo.thumbnailURL;
  thumbnail.classList.remove('hidden');
  
  var deviceName = document.querySelector('#device-name');
  deviceName.textContent = deviceInfo.deviceName;
  
  var productId = document.querySelector('#device-product-id');
  productId.textContent = deviceInfo.productId;
  
  var vendorId = document.querySelector('#device-vendor-id');
  vendorId.textContent = deviceInfo.vendorId;
  
  $('a[href="#device-info"]').tab('show');
}

function enumerateDevices() {
  chrome.nfc.findDevices(function(devices) {
    device = devices[0];
    showDeviceInfo(); 
  });
}

enumerateDevices();

document.querySelector('#read-ndef pre').textContent = readNdefTag.toString();
document.querySelector('#read-ndef button').addEventListener('click', onReadNdefTagButtonClicked);

document.querySelector('#read-mifare pre').textContent = readMifareTag.toString();
document.querySelector('#read-mifare button').addEventListener('click', onReadMifareTagButtonClicked);

document.querySelector('#write-ndef pre').textContent = writeNdefTag.toString();
document.querySelector('#write-ndef button').addEventListener('click', onWriteNdefTagButtonClicked);

document.querySelector('#write-mifare pre').textContent = writeMifareTag.toString();
document.querySelector('#write-mifare button').addEventListener('click', onWriteMifareTagButtonClicked);

document.querySelector('#emulate pre').textContent = emulateTag.toString();
document.querySelector('#emulate button').addEventListener('click', onEmulateTagButtonClicked);

$('a[data-toggle="tab"]').on('shown.bs.tab', function (e) {
  document.querySelector('#logContainer').classList.add('small');
});

document.querySelector('.drawer').addEventListener('click', function(e) {
  document.querySelector('#logContainer').classList.toggle('small');
});