Browserified MQTT.js defaults to connecting to localhost instead of server URL

[dstolpmann]

I am using the MQTT.js version from https://unpkg.com in the browser and experience the following issue.

In old versions (<=4.1.0), MQTT.js used to connect to the host that served the website and also used the same port if connect() was called without an URL. I do not know if it also selected wss over ws if the page was served via HTTPS, as I never used TLS.

Starting with 4.2.1 (4.2.0 does not work in the browser) and also in the current 5.1.4 release, calling connect() without an URL always connects to ws://localhost/.

This change in behavior was probably introduced in #1108.

I worked around this issue by using the following command:

mqtt.connect((location.protocol == "https:" ? "wss" : "ws") + "://" + location.hostname + ":" + location.port)

[robertsLando]

@BrandonSmith would you like to submit a pr to fix this issue? you could use the is-browser const to detect the environment and based on that use localhost or the other default url

[haihuynhDF]

I also meet this issue when trying to connect MQTT from ReactJS

It connects to localhost instead of the host which I config in the option

But it works when I connect from NodeJS

This is my source code

const opt: mqtt.IClientOptions = {
  host,
  protocol: "mqtt",
  clientId,
  clean: true,
  key,
  cert,
  ca,
  reconnectPeriod: 0,
};

const client: MqttClient = mqtt.connect(opt);

client.on('connect', () => {
  console.log('client connected');
  client.publish(
    `topic`,
    "abc",
  );
})

[robertsLando]

You should not provide an host in options in order to have it connecting to document url

MQTT.js/src/lib/connect/ws.ts

Line 78 in 6591404

options.hostname = parsed.hostname