Edit in JSFiddle

const main = async () => {
  // Use code snippet from connecting to MQTT section
  const client = connect();
  
  const topic = 'OrgnisationID/Arrived/AssetID';
  
  client.subscribe(topic);
  
  client.on('message', (topic, message) => {
    // message is in Buffer format
    console.log(message.toString())
  
    // Run your bespoke logic here
  });
};

main();