ReadDeviceToCloud.js

// based on: https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-node-node-getstarted#receive-device-to-cloud-messages
const EventHubClient = require('azure-event-hubs').Client;

const connectionString = '{iothub connection string}';

const printError = (err) => {
  console.err(err.message);
}

const printMessage = (message) => {
  console.log('Message received: ');
  console.log(JSON.stringify(message.body));
  console.log('');
}

const client = EventHubClient.fromConnectionString(connectionString);
client.open()
.then(client.getPartitionIds.bind(client))
.then((partitionIds) => {
  return partitionIds.map((partitionId) => {
    return client.createReceiver('$Default', partitionId, {'startAfterTime': Date.now()})
    .then((receiver) => {
      console.log('Created partition receiver: ' + partitionId);
      receiver.on('errorReceived', printError);
      receiver.on('message', printMessage)
    })
  })
})
.catch(printError);