Paho JavaScript Client 基于websocket实现 mqtt客户端

// Create a client instance
//注意不要在client前写var
client = new Paho.MQTT.Client(location.hostname, Number(location.port), "clientId");
// set callback handlers
client.onConnectionLost = onConnectionLost;
client.onMessageArrived = onMessageArrived;
// connect the client
client.connect({onSuccess:onConnect});
// called when the client connects
function onConnect() {
  // Once a connection has been made, make a subscription and send a message.
  console.log("onConnect");
  client.subscribe("World");
  message = new Paho.MQTT.Message("Hello");
  message.destinationName = "World";
  client.send(message);
}
// called when the client loses its connection
function onConnectionLost(responseObject) {
  if (responseObject.errorCode !== 0) {
    console.log("onConnectionLost:"+responseObject.errorMessage);
  }
}
// called when a message arrives
function onMessageArrived(message) {
  console.log("onMessageArrived:"+message.payloadString);
}