MQTTClient.onMessage()

Overview

Used to set or replace the general message handler for an MQTTClient object.

Added in version 2.1.13

Format

var mqttClient = new MQTTClient(options);
//...
mqttClient.onMessage = messageHandler;

Value	Description	Type	Required	Notes
messageHandler	A callback function that is called when a message is received.	Function	Optional	When called, the first parameter is a Message object as described below.

Message object properties

Value	Description	Type	Notes
topic	The topic for the message.	String
payload	An ArrayBuffer containing the payload for the message.	ArrayBuffer
qos	The quality of service for the message.	Integer	Will use the lowest of either the subscription QoS level or the sent message QoS level. Possible values: 0 – at most once, where messages are delivered according to the best efforts of the operating environment. Message loss can occur. 1 – at least once, where messages are assured to arrive but duplicates can occur. 2 – exactly once, where messages are assured to arrive exactly once.
retain	A flag indicating if this message is a retained message	Boolean
payloadAsString	The payload bytes decoded as a UTF-8 string.	string

Example

Copy

/* Connect and subscribe to the "toast/for/all" topic, and show a toast for each message.
 */

mqttClient = new MQTTClient({
    broker: "mqtt://mymqtt.example.com",
    subscribeTo: [ "toast/for/all" ]
});

mqttClient.connect();

mqttClient.onMessage = function(message) {
    if(message.topic === "toast/for/all") {
        View.toast(message.payloadAsString, true);
    }
};