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I'm attempting to get a working example of mqttjs in nodejs. I'm receiving this error while attempting to execute my main.js file using command node main.js in Windows 10 cmd prompt:

error:

C:\Users\Rich\Documents\Code\nodejs\onoff\node_modules\mqtt\lib\connect\index.js:64
      throw new Error('Missing protocol')
Error: Missing protocol
    at Object.connect (C:\Users\Rich\Documents\Code\nodejs\onoff\node_modules\mqtt\lib\connect\index.js:64:13)
    at Object.<anonymous> (C:\Users\Rich\Documents\Code\nodejs\onoff\main.js:2:20)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Function.Module.runMain (module.js:693:10)
    at startup (bootstrap_node.js:188:16)
    at bootstrap_node.js:609:3
code:
var mqtt = require('mqtt');
var client  = mqtt.connect('192.168.0.22');
client.on('connect', function () {
  client.subscribe('mydevice')
  client.publish('presence', 'Hello mqtt')
client.on('message', function (topic, message) {
  // message is Buffer
  console.log(message.toString())
  client.end()
It's because (as the error states) you've missed the protocol out of the URI that needs to be passed to the connect() method.
You have passed a raw IP address, but it needs to be a URI, including a protocol and a host.
var client  = mqtt.connect('mqtt://192.168.0.22')
This is shown in the examples in the README.md that is included with the package both on github and npm.
It is also described in the API docs:
  
mqtt.connect([url], options)
  
Connects to the broker specified by the given url and options and
  returns a Client.
  
The URL can be on the following protocols: 'mqtt', 'mqtts', 'tcp',
  'tls', 'ws', 'wss'. The URL can also be an object as returned by
  URL.parse(), in that case the two objects are merged, i.e. you can
  pass a single object with both the URL and the connect options
        
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