npm i mqtt

<script src="https://unpkg.com/mqtt/dist/mqtt.min.js"></script>
<script>
    // Initialize a global mqtt variable.
    console.log(mqtt)
</script>

npm i mqtt -g

mqtt help

MQTT.js command line interface, available commands are:

  * publish     publish a message to the broker
  * subscribe   subscribe for updates from the broker
  * version     the current MQTT.js version
  * help        help about commands

Launch 'mqtt help [command]' to know more about the commands.

// const mqtt = require('mqtt')
import mqtt from 'mqtt'

// Connection options
const options = {
      clean: true, // true: Clear session, false: Retain session
      connectTimeout: 4000, // Timeout period
      // Certification information
      clientId: '<your-client-id>',
      username: '<your-username>',
      password: '<your-password>',
}

// Connection string, which specifies the connection method via the protocol
// ws unencrypted WebSocket connection
// wss encrypted WebSocket connection
// mqtt unencrypted TCP connection
// mqtts encrypted TCP connection
// wxs WeChat mini program connection
// alis Alipay mini program connection
const connectUrl = 'wss://mqtt-xxx.mqtt.tencenttdmq.com:8084/mqtt'
const client = mqtt.connect(connectUrl, options)

client.on('reconnect', (error) => {
    console.log('Reconnecting:', error)
})

client.on('error', (error) => {
    console.log('Connection failure:', error)
})

client.on('message', (topic, message) => {
  console.log('received message:', topic, message.toString())
})