Connect with JavaScript
Below is an example using MQTT.js with the TOKEN authentication mode configured on a broker. The example assumes you have Node.js v16 or higher installed on your system.
Make sure to set the BROKER_URI
(e.g. mqtts://YOUR-BROKER.YOUR-NAMESPACE.cloudflarepubsub.com
), BROKER_TOKEN
(a valid auth token), and BROKER_TOPIC
environmental variables before running the example program.
# Pre-requisite: install MQTT.jsnpm install mqtt --save
Copy the following example as example.js
and run it with node example.js
.
const mqtt = require("mqtt");
// Specify MQTT broker URI: mqtts://<broker name>.<namespace>.cloudflarepubsub.com
const uri = check_env(process.env.BROKER_URI);
// Any username and your token from the /brokers/YOUR_BROKER/credentials endpoint
// The token should be the base64-encoded JWT issued by the Pub/Sub API
const username = "anything";
const password = check_env(process.env.BROKER_TOKEN);
// Specify a topic name to subscribe to and publish on
let topic = check_env(process.env.BROKER_TOPIC);
// Configure and create the MQTT client
const client = mqtt.connect(uri, { protocolVersion: 5, port: 8883, clean: true, connectTimeout: 2000, // 2 seconds clientId: "", username, password,
});
// Emit errors and exitclient.on("error", function (err) { console.log(`⚠️ error: ${err}`); client.end(); process.exit();
});
// Connect to your brokerclient.on("connect", function () { console.log(`🌎 connected to ${process.env.BROKER_URI}!`); // Subscribe to a topic client.subscribe(topic, function (err) { if (!err) { console.log(`✅ subscribed to ${topic}`); // Publish a message! client.publish(topic, "My first MQTT message"); } });
});
// Start waiting for messagesclient.on("message", async function (topic, message) { console.log(`received a message: ${message.toString()}`);
// Goodbye! client.end(); process.exit();
});
// Return variable or throw error
function check_env(env) { if (!env) { throw "BROKER_URI, BROKER_TOKEN and BROKER_TOPIC must be set."; }
return env;
}