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);
}
};