Example of robustly subscribing to BLE gatt characteristicvaluechanged

Hi!

I've had a look through the apps and examples, apologies if I missed it:

I'm seeking an example of robustly maintaining a connection to a BLE device so we can receive characteristicvaluechanged events.

I have this so far, but it lacks retrying everything, handling failures, and so on. I'm unfamiliar with JavaScript. If there's no off-the-shelf example of how to be robust, I'll give it a go and share back here...

NRF.requestDevice({ filters: [{ namePrefix: 'XXXX' }] }).then(function(device) {
  console.log("Found");
  return device.gatt.connect();
}).then(function(g) {
  console.log("Connected");
  gatt = g;
  return gatt.getPrimaryService(
    ".......");
}).then(function(service) {
  console.log("Got Service");
  return service.getCharacteristic(
    "......");
}).then(function (c) {
  console.log("Got Characteristic");
  characteristic = c;
  characteristic.on('characteristicvaluechanged', function(event) {
    console.log("Got event");
    console.log(event.target.value.buffer);
    parseMessage(event.target.value.buffer);
  });
  return characteristic.startNotifications();
});