mqtt.js

var mqtt    = require('mqtt');
// Connect to Broker
var client  = mqtt.connect('mqtt://test.mosquitto.org');
 
client.on('connect', function () {
  client.subscribe('chatroom'); // Subcribre to a `chatroom` topic
  client.publish('chatroom', 'Hello mqtt'); // Publish a message to `chatroom` topic
});
 
client.on('message', function (topic, message) {
  // message is Buffer => parse into String
  console.log(message.toString());
  client.end();
});