Paho MQTT Javascript subscription to multiple topics?

Question

How can I do subscription to multiple topics and log content on receive ?

function subscribe()
{
   var topic = "Device/MainTopic1/";
   var topic1 = "Device/MainTopic2/";
   var qos = "0";

   client.subscribe([(topic, {qos: Number(qos)}), (topic1, {qos: Number(qos)})]); // Not working
		
   client.subscribe(topic,{qos: Number(qos)}); // Single topic Working - Could only invoke once	
}

Currently based on my current research found this issue logged in git. Any pointers would help. https://github.com/eclipse/paho.mqtt.javascript/issues/16

Edit the question to include what code you already have and somebody will help you fix it. — hardillb

hardillb hardillb · Accepted Answer · 2016-11-17T10:23:04

As mentioned in the comment on that git issue you can just call subscribe multiple times with each topic you need. There is no single call to subscribe to multiple topics in the Javascript client at this time.

function subscribe()
{
    var topic = "Device/MainTopic1";
    var topic1 = "Device/MainTopic2";
    var qos = 0;

    client.subscribe(topic,{qos: qos});
    client.subscribe(topoic1,{qos:qos});
}

This should work just fine.

Also topics should not have trailing or leading '/' chars, they add null elements to the topic tree that make them harder wild card properly

Paho MQTT Javascript subscription to multiple topics?

1 Answers