How to extract values of multiple topics in onMessageArrived(message) function of Paho MQTT JavaScript API?

Question

I have created a Publisher Script using Paho MQTT JavaScript API which publishes values to two topics MyHome/Temp and MyHome/Hum. The script is running successfully and publishing data to CloudMQTT broker. In my Subscriber script I have subscribed to these two topics and printing them in Console as following:

function onConnect() {
  console.log("onConnect");
  client.subscribe("MyHome/Temp");
  client.subscribe("MyHome/Hum");
}

function onMessageArrived(message) { 
  console.log(message.destinationName +" : "+ message.payloadString);
}

It is printing both the topic names and corresponding values. Now I want to extract the values of both topics using message.payloadString and store in variable as following:

function onMessageArrived(message) { 
  var temp = message.payloadString;
  var hum = message.payloadString;
  ...
}

But I am getting only on value in both variable i.e. the value of last topic 'hum'. Can anyone please help me solving this.

Answer 1

onMessageArrived will be called separately for each message that arrives so if the payload only contains one value then you will only be able to get one value at a time.

You need to include a if statement in the onMessageArrived callback to determine which topic the message arrived on and then set the respective value.