espr_mqtt.js

console.log("init");

const WIFI_SSID = "...";
const WIFI_PASS = "...";

const MQTT_CLIENT_ID = "...";
const MQTT_HOST = "dev.rightech.io";

let mqtt;

function connectMqtt() {
  mqtt = require("MQTT").connect({
    client_id: MQTT_CLIENT_ID,
    host: MQTT_HOST,
  });

  mqtt.on("connected", () => {
    console.log("mqtt connected");

    mqtt.publish("hello", JSON.stringify({ n: Date.now(), r: Math.random() }));
  });

  mqtt.on("disconnected", () => {
    console.log("mqtt disconnected");
  });

  mqtt.on("publish", (pub) => {
    console.log(`publish received: ${pub.topic}: ${pub.message}`);
  });

  mqtt.on("error", (message) => {
    console.log(`mqtt error: ${message}`);
  });
}

require("Wifi").connect(WIFI_SSID, { password: WIFI_PASS }, (err) => {
  if (err) {
    console.log(`wifi error: ${err}`);
    return;
  }
  console.log("wifi connected");
  connectMqtt();
});

>
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|  __|___ ___ ___ _ _|_|___ ___
|  __|_ -| . |  _| | | |   | . |
|____|___|  _|_| |___|_|_|_|___|
         |_| espruino.com
 2v08 (c) 2019 G.Williams
Espruino is Open Source. Our work is supported
only by sales of official boards and donations:
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Flash map 4MB:512/512, manuf 0xe chip 0x4015

init
wifi connected
mqtt connected

>
publish received: base/relay/led1: 1
publish received: base/relay/led1: 0
publish received: base/relay/led1: 1

>mqtt.publish('hello', 'ric')
=undefined
>